Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream-aquifer-land interactions (CP v1.0)

NASA Astrophysics Data System (ADS)

Bisht, Gautam; Huang, Maoyi; Zhou, Tian; Chen, Xingyuan; Dai, Heng; Hammond, Glenn E.; Riley, William J.; Downs, Janelle L.; Liu, Ying; Zachara, John M.

2017-12-01

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater-river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater-river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater-river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

DOE PAGES

Bisht, Gautam; Huang, Maoyi; Zhou, Tian; ...

2017-12-12

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year periodmore » to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisht, Gautam; Huang, Maoyi; Zhou, Tian

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate themore » impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

DOE PAGES

Bisht, Gautam; Huang, Maoyi; Zhou, Tian; ...

2017-01-01

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate themore » impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisht, Gautam; Huang, Maoyi; Zhou, Tian

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year periodmore » to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Demonstrating usefulness of real-time monitoring at streambank wells coupled with active streamgages - Pilot studies in Wyoming, Montana, and Mississippi

USGS Publications Warehouse

Eddy-Miller, Cheryl A.; Constantz, Jim; Wheeler, Jerrod D.; Caldwell, Rodney R.; Barlow, Jeannie R.B.

2012-01-01

Groundwater and surface water in many cases are considered separate resources, but there is growing recognition of a need to treat them as a single resource. For example, groundwater inflow during low streamflow is vitally important to the health of a stream for many reasons, including buffering temperature, providing good quality water to the stream, and maintaining flow for aquatic organisms. The U.S. Geological Survey (USGS) has measured stream stage and flow at thousands of locations since 1889 and has the ability to distribute the information to the public within hours of collection, but collecting shallow groundwater data at co-located measuring sites is a new concept. Recently developed techniques using heat as a tracer to quantify groundwater and surface-water exchanges have shown the value of coupling these resources to increase the understanding of the water resources of an area. In 2009, the USGS Office of Groundwater began a pilot study to examine the feasibility and utility of widespread use of real-time groundwater monitoring at streambank wells coupled with real-time surface-water monitoring at active streamgages to assist in understanding the exchange of groundwater and surface water in a cost effective manner.

Local feedback mechanisms of the shallow water region around the Maritime Continent

NASA Astrophysics Data System (ADS)

Xue, Pengfei; Eltahir, Elfatih A. B.; Malanotte-Rizzoli, Paola; Wei, Jun

2014-10-01

The focus of this study is the local-scale air-sea feedback mechanisms over the shallow shelf water region (water depth <200 m) of the Maritime Continent (MC). MC was selected as a pilot study site for its extensive shallow water coverage, geographic complexity, and importance in the global climate system. To identify the local-scale air-sea feedback processes, we ran numerical experiments with perturbed surface layer water temperature using a coupled ocean-atmosphere model and an uncoupled ocean model. By examining the responses of the coupled and uncoupled models to the water temperature perturbation, we identify that, at a local-scale, a negative feedback process through the coupled dynamics that tends to restore the SST from its perturbation could dominate the shallow water region of the MC at a short time scale of several days. The energy budget shows that 38% of initial perturbation-induced heat energy was adjusted through the air-sea feedback mechanisms within 2 weeks, of which 58% is directly transferred into the atmosphere by the adjustment of latent heat flux due to the evaporative cooling mechanism. The increased inputs of heat and moisture into the lower atmosphere then modifies its thermal structure and increases the formation of low-level clouds, which act as a shield preventing incoming solar radiation from reaching the sea surface, accounts for 38% of the total adjustment of surface heat fluxes, serving as the second mechanism for the negative feedback process. The adjustment of sensible heat flux and net longwave radiation play a secondary role. The response of the coupled system to the SST perturbation suggests a response time scale of the coupled feedback process of about 3-5 days. The two-way air-sea feedback tightly links the surface heat fluxes, clouds and SST, and can play an important role in regulating the short-term variability of the SST over the shallow shelf water regions.

Mathematical modelling of surface water-groundwater flow and salinity interactions in the coastal zone

NASA Astrophysics Data System (ADS)

Spanoudaki, Katerina; Kampanis, Nikolaos A.

2014-05-01

Coastal areas are the most densely-populated areas in the world. Consequently water demand is high, posing great pressure on fresh water resources. Climatic change and its direct impacts on meteorological variables (e.g. precipitation) and indirect impact on sea level rise, as well as anthropogenic pressures (e.g. groundwater abstraction), are strong drivers causing groundwater salinisation and subsequently affecting coastal wetlands salinity with adverse effects on the corresponding ecosystems. Coastal zones are a difficult hydrologic environment to represent with a mathematical model due to the large number of contributing hydrologic processes and variable-density flow conditions. Simulation of sea level rise and tidal effects on aquifer salinisation and accurate prediction of interactions between coastal waters, groundwater and neighbouring wetlands requires the use of integrated surface water-groundwater models. In the past few decades several computer codes have been developed to simulate coupled surface and groundwater flow. In these numerical models surface water flow is usually described by the 1-D Saint Venant equations (e.g. Swain and Wexler, 1996) or the 2D shallow water equations (e.g. Liang et al., 2007). Further simplified equations, such as the diffusion and kinematic wave approximations to the Saint Venant equations, are also employed for the description of 2D overland flow and 1D stream flow (e.g. Gunduz and Aral, 2005). However, for coastal bays, estuaries and wetlands it is often desirable to solve the 3D shallow water equations to simulate surface water flow. This is the case e.g. for wind-driven flows or density-stratified flows. Furthermore, most integrated models are based on the assumption of constant fluid density and therefore their applicability to coastal regions is questionable. Thus, most of the existing codes are not well-suited to represent surface water-groundwater interactions in coastal areas. To this end, the 3D integrated surface water-groundwater model IRENE (Spanoudaki et al., 2009; Spanoudaki, 2010) has been modified in order to simulate surface water-groundwater flow and salinity interactions in the coastal zone. IRENE, in its original form, couples the 3D, non-steady state Navier-Stokes equations, after Reynolds averaging and with the assumption of hydrostatic pressure distribution, to the equations describing 3D saturated groundwater flow of constant density. A semi-implicit finite difference scheme is used to solve the surface water flow equations, while a fully implicit finite difference scheme is used for the groundwater equations. Pollution interactions are simulated by coupling the advection-diffusion equation describing the fate and transport of contaminants introduced in a 3D turbulent flow field to the partial differential equation describing the fate and transport of contaminants in 3D transient groundwater flow systems. The model has been further developed to include the effects of density variations on surface water and groundwater flow, while the already built-in solute transport capabilities are used to simulate salinity interactions. Initial results show that IRENE can accurately predict surface water-groundwater flow and salinity interactions in coastal areas. Important research issues that can be investigated using IRENE include: (a) sea level rise and tidal effects on aquifer salinisation and the configuration of the saltwater wedge, (b) the effects of surface water-groundwater interaction on salinity increase of coastal wetlands and (c) the estimation of the location and magnitude of groundwater discharge to coasts. Acknowledgement The work presented in this paper has been funded by the Greek State Scholarships Foundation (IKY), Fellowships of Excellence for Postdoctoral Studies (Siemens Program), 'A simulation-optimization model for assessing the best practices for the protection of surface water and groundwater in the coastal zone', (2013 - 2015). References Gunduz, O. and Aral, M.M. (2005). River networks and groundwater flow: a simultaneous solution of a coupled system. Journal of Hydrology 301 (1-4), 216-234. Liang, D., Falconer, R.A. and Lin, B. (2007). Coupling surface and subsurface flows in a depth-averaged flood wave model. Journal of Hydrology 337, 147-158. Spanoudaki, K., Stamou, A.I. and Nanou-Giannarou, A. (2009). Development and verification of a 3-D integrated surface water-groundwater model. Journal of Hydrology, 375 (3-4), 410-427. Spanoudaki, K. (2010). Integrated numerical modelling of surface water groundwater systems (in Greek). Ph.D. Thesis, National Technical University of Athens, Greece. Swain, E.D. and Wexler, E.J. (1996). A coupled surface water and groundwater flow model (Modbranch) for simulation of stream-aquifer interaction. United States Geological Survey, Techniques of Water Resources Investigations (Book 6, Chapter A6).

GSFLOW - Coupled Ground-Water and Surface-Water Flow Model Based on the Integration of the Precipitation-Runoff Modeling System (PRMS) and the Modular Ground-Water Flow Model (MODFLOW-2005)

USGS Publications Warehouse

Markstrom, Steven L.; Niswonger, Richard G.; Regan, R. Steven; Prudic, David E.; Barlow, Paul M.

2008-01-01

The need to assess the effects of variability in climate, biota, geology, and human activities on water availability and flow requires the development of models that couple two or more components of the hydrologic cycle. An integrated hydrologic model called GSFLOW (Ground-water and Surface-water FLOW) was developed to simulate coupled ground-water and surface-water resources. The new model is based on the integration of the U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) and the U.S. Geological Survey Modular Ground-Water Flow Model (MODFLOW). Additional model components were developed, and existing components were modified, to facilitate integration of the models. Methods were developed to route flow among the PRMS Hydrologic Response Units (HRUs) and between the HRUs and the MODFLOW finite-difference cells. This report describes the organization, concepts, design, and mathematical formulation of all GSFLOW model components. An important aspect of the integrated model design is its ability to conserve water mass and to provide comprehensive water budgets for a location of interest. This report includes descriptions of how water budgets are calculated for the integrated model and for individual model components. GSFLOW provides a robust modeling system for simulating flow through the hydrologic cycle, while allowing for future enhancements to incorporate other simulation techniques.

Coupling a three-dimensional subsurface flow model with a land surface model to simulate stream-aquifer-land interactions

NASA Astrophysics Data System (ADS)

Huang, M.; Bisht, G.; Zhou, T.; Chen, X.; Dai, H.; Hammond, G. E.; Riley, W. J.; Downs, J.; Liu, Y.; Zachara, J. M.

2016-12-01

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively-parallel multi-physics reactive tranport model (PFLOTRAN). The coupled model (CLM-PFLOTRAN) is applied to a 400m×400m study domain instrumented with groundwater monitoring wells in the Hanford 300 Area along the Columbia River. CLM-PFLOTRAN simulations are performed at three different spatial resolutions over the period 2011-2015 to evaluate the impact of spatial resolution on simulated variables. To demonstrate the difference in model simulations with and without lateral subsurface flow, a vertical-only CLM-PFLOTRAN simulation is also conducted for comparison. Results show that the coupled model is skillful in simulating stream-aquifer interactions, and the land-surface energy partitioning can be strongly modulated by groundwater-river water interactions in high water years due to increased soil moisture availability caused by elevated groundwater table. In addition, spatial resolution does not seem to impact the land surface energy flux simulations, although it is a key factor for accurately estimating the mass exchange rates at the boundaries and associated biogeochemical reactions in the aquifer. The coupled model developed in this study establishes a solid foundation for understanding co-evolution of hydrology and biogeochemistry along the river corridors under historical and future hydro-climate changes.

The role of evapotranspiration fluxes in summertime precipitation in Central Europe: coupled groundwater-atmosphere simulations with the WRF-LEAFHYDRO system.

NASA Astrophysics Data System (ADS)

Regueiro Sanfiz, Sabela; Gómez, Breo; Miguez Macho, Gonzalo

2017-04-01

Because of its continental position, Central Europe summertime rainfall is largely dependent on local or regional dynamics, with precipitation water possibly also significantly dependent on local sources. We investigate here land-atmosphere feedbacks over inland Europe focusing in particular on evapotranspiration-soil moisture connections and precipitation recycling ratios. For this purpose, a set of simulations were performed with the Weather Research and Forecasting (WRF) model coupled to LEAFHYDRO soil-vegetation-hydrology model. The LEAFHYDRO Land Surface Model includes a groundwater parameterization with a dynamic water table fully coupling groundwater to the soil-vegetation and surface waters via two-way fluxes. A water tagging capability in the WRF model is used to quantify evapotranspiration contribution to precipitation over the region. Several years are considered, including summertime 2002, during which severe flooding occurred. Preliminary results from our simulations highlight the link of large areas with shallow water with high air moisture values through the summer season; and the importance of the contribution of evapotranspiration to summertime precipitation. Consequently, results show the advantages of using a fully coupled hydrology-atmospheric modeling system.

Contrasting Cloud Composition Between Coupled and Decoupled Marine Boundary Layer Clouds

NASA Astrophysics Data System (ADS)

WANG, Z.; Mora, M.; Dadashazar, H.; MacDonald, A.; Crosbie, E.; Bates, K. H.; Coggon, M. M.; Craven, J. S.; Xian, P.; Campbell, J. R.; AzadiAghdam, M.; Woods, R. K.; Jonsson, H.; Flagan, R. C.; Seinfeld, J.; Sorooshian, A.

2016-12-01

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (E-PEACE 2011, NiCE 2013, BOAS 2015). Decoupled clouds exhibited significantly lower overall mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and sub-cloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Non-refractory sub-micrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Total cloud water mass concentration in coupled clouds was dominated by sodium and chloride, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea salt constituents (e.g., Cl, Na, Mg, K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. These results suggest that an important variable is the extent to which clouds are coupled to the surface layer when interpreting microphysical data relevant to clouds and aerosol particles.

Modelling global nitrogen export to ground and surface water from natural ecosystems: impact of N deposition, climate, and CO2 concentration

NASA Astrophysics Data System (ADS)

Braakhekke, Maarten; Rebel, Karin; Dekker, Stefan; van Beek, Rens; Bierkens, Marc; Smith, Ben; Wassen, Martin

2015-04-01

For large regions in the world strong increases in atmospheric nitrogen (N) deposition are predicted as a result of emissions from fossil fuel combustion and food production. This will cause many previously N limited ecosystems to become N saturated, leading to increased export to ground and surface water and negative impacts on the environment and human health. However, precise N export fluxes are difficult to predict. Due to its strong link to carbon, N in vegetation and soil is also determined by productivity, as affected by rising atmospheric CO2 concentration and temperature, and denitrification. Furthermore, the N concentration of water delivered to streams depends strongly on local hydrological conditions. We aim to study how N delivery to ground and surface water is affected by changes in environmental factors. To this end we are developing a global dynamic modelling system that integrates representations of N cycling in vegetation and soil, and N delivery to ground and surface water. This will be achieved by coupling the dynamic global vegetation model LPJ-GUESS, which includes representations of N cycling, as well as croplands and pasture, to the global water balance model PCR-GLOBWB, which simulates surface runoff, interflow, groundwater recharge, and baseflow. This coupling will allow us to trace N across different systems and estimate the input of N into the riverine system which can be used as input for river biogeochemical models. We will present large scale estimates of N leaching and transport to ground and surface water for natural ecosystems in different biomes, based on a loose coupling of the two models. Furthermore, by means of a factorial model experiment we will explore how these fluxes are influenced by N deposition, temperature, and CO2 concentration.

Effect of inlet modelling on surface drainage in coupled urban flood simulation

NASA Astrophysics Data System (ADS)

Jang, Jiun-Huei; Chang, Tien-Hao; Chen, Wei-Bo

2018-07-01

For a highly developed urban area with complete drainage systems, flood simulation is necessary for describing the flow dynamics from rainfall, to surface runoff, and to sewer flow. In this study, a coupled flood model based on diffusion wave equations was proposed to simulate one-dimensional sewer flow and two-dimensional overland flow simultaneously. The overland flow model provides details on the rainfall-runoff process to estimate the excess runoff that enters the sewer system through street inlets for sewer flow routing. Three types of inlet modelling are considered in this study, including the manhole-based approach that ignores the street inlets by draining surface water directly into manholes, the inlet-manhole approach that drains surface water into manholes that are each connected to multiple inlets, and the inlet-node approach that drains surface water into sewer nodes that are connected to individual inlets. The simulation results were compared with a high-intensity rainstorm event that occurred in 2015 in Taipei City. In the verification of the maximum flood extent, the two approaches that considered street inlets performed considerably better than that without street inlets. When considering the aforementioned models in terms of temporal flood variation, using manholes as receivers leads to an overall inefficient draining of the surface water either by the manhole-based approach or by the inlet-manhole approach. Using the inlet-node approach is more reasonable than using the inlet-manhole approach because the inlet-node approach greatly reduces the fluctuation of the sewer water level. The inlet-node approach is more efficient in draining surface water by reducing flood volume by 13% compared with the inlet-manhole approach and by 41% compared with the manhole-based approach. The results show that inlet modeling has a strong influence on drainage efficiency in coupled flood simulation.

Simulations of ecosystem hydrological processes using a unified multi-scale model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiaofan; Liu, Chongxuan; Fang, Yilin

2015-01-01

This paper presents a unified multi-scale model (UMSM) that we developed to simulate hydrological processes in an ecosystem containing both surface water and groundwater. The UMSM approach modifies the Navier–Stokes equation by adding a Darcy force term to formulate a single set of equations to describe fluid momentum and uses a generalized equation to describe fluid mass balance. The advantage of the approach is that the single set of the equations can describe hydrological processes in both surface water and groundwater where different models are traditionally required to simulate fluid flow. This feature of the UMSM significantly facilitates modelling ofmore » hydrological processes in ecosystems, especially at locations where soil/sediment may be frequently inundated and drained in response to precipitation, regional hydrological and climate changes. In this paper, the UMSM was benchmarked using WASH123D, a model commonly used for simulating coupled surface water and groundwater flow. Disney Wilderness Preserve (DWP) site at the Kissimmee, Florida, where active field monitoring and measurements are ongoing to understand hydrological and biogeochemical processes, was then used as an example to illustrate the UMSM modelling approach. The simulations results demonstrated that the DWP site is subject to the frequent changes in soil saturation, the geometry and volume of surface water bodies, and groundwater and surface water exchange. All the hydrological phenomena in surface water and groundwater components including inundation and draining, river bank flow, groundwater table change, soil saturation, hydrological interactions between groundwater and surface water, and the migration of surface water and groundwater interfaces can be simultaneously simulated using the UMSM. Overall, the UMSM offers a cross-scale approach that is particularly suitable to simulate coupled surface and ground water flow in ecosystems with strong surface water and groundwater interactions.« less

Photo-induced water oxidation at the aqueous GaN (101¯0) interface: Deprotonation kinetics of the first proton-coupled electron-transfer step

DOE PAGES

Ertem, Mehmed Z.; Kharche, Neerav; Batista, Victor S.; ...

2015-03-12

Photoeclectrochemical water splitting plays a key role in a promising path to the carbon-neutral generation of solar fuels. Wurzite GaN and its alloys ( e.g., GaN/ZnO and InGaN) are demonstrated photocatalysts for water oxidation, and they can drive the overall water splitting reaction when coupled with co-catalysts for proton reduction. In the present work, we investigate the water oxidation mechanism on the prototypical GaN (101¯0) surface using a combined ab initio molecular dynamics and molecular cluster model approach taking into account the role of water dissociation and hydrogen bonding within the first solvation shell of the hydroxylated surface. The investigationmore » of free-energy changes for the four proton-coupled electron-transfer (PCET) steps of the water oxidation mechanism shows that the first PCET step for the conversion of –Ga-OH to –Ga-O˙⁻ requires the highest energy input. We further examine the sequential PCETs, with the proton transfer (PT) following the electron transfer (ET), and find that photo-generated holes localize on surface –NH sites is thermodynamically more favorable than –OH sites. However, proton transfer from –OH sites with subsequent localization of holes on oxygen atoms is kinetically favored owing to hydrogen bonding interactions at the GaN (101¯0)–water interface. We find that the deprotonation of surface –OH sites is the limiting factor for the generation of reactive oxyl radical ion intermediates and consequently for water oxidation.« less

A coupled surface-water and ground-water flow model (MODBRANCH) for simulation of stream-aquifer interaction

USGS Publications Warehouse

Swain, Eric D.; Wexler, Eliezer J.

1996-01-01

Ground-water and surface-water flow models traditionally have been developed separately, with interaction between subsurface flow and streamflow either not simulated at all or accounted for by simple formulations. In areas with dynamic and hydraulically well-connected ground-water and surface-water systems, stream-aquifer interaction should be simulated using deterministic responses of both systems coupled at the stream-aquifer interface. Accordingly, a new coupled ground-water and surface-water model was developed by combining the U.S. Geological Survey models MODFLOW and BRANCH; the interfacing code is referred to as MODBRANCH. MODFLOW is the widely used modular three-dimensional, finite-difference ground-water model, and BRANCH is a one-dimensional numerical model commonly used to simulate unsteady flow in open- channel networks. MODFLOW was originally written with the River package, which calculates leakage between the aquifer and stream, assuming that the stream's stage remains constant during one model stress period. A simple streamflow routing model has been added to MODFLOW, but is limited to steady flow in rectangular, prismatic channels. To overcome these limitations, the BRANCH model, which simulates unsteady, nonuniform flow by solving the St. Venant equations, was restructured and incorporated into MODFLOW. Terms that describe leakage between stream and aquifer as a function of streambed conductance and differences in aquifer and stream stage were added to the continuity equation in BRANCH. Thus, leakage between the aquifer and stream can be calculated separately in each model, or leakages calculated in BRANCH can be used in MODFLOW. Total mass in the coupled models is accounted for and conserved. The BRANCH model calculates new stream stages for each time interval in a transient simulation based on upstream boundary conditions, stream properties, and initial estimates of aquifer heads. Next, aquifer heads are calculated in MODFLOW based on stream stages calculated by BRANCH, aquifer properties, and stresses. This process is repeated until convergence criteria are met for head and stage. Because time steps used in ground-water modeling can be much longer than time intervals used in surface- water simulations, provision has been made for handling multiple BRANCH time intervals within one MODFLOW time step. An option was also added to BRANCH to allow the simulation of channel drying and rewetting. Testing of the coupled model was verified by using data from previous studies; by comparing results with output from a simpler, four-point implicit, open-channel flow model linked with MODFLOW; and by comparison to field studies of L-31N canal in southern Florida.

The Significant Surface-Water Connectivity of “Geographically Isolated Wetlands”

EPA Science Inventory

We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of g...

Numerical modeling of coupled water flow and heat transport in soil and snow

Treesearch

Thijs J. Kelleners; Jeremy Koonce; Rose Shillito; Jelle Dijkema; Markus Berli; Michael H. Young; John M. Frank; William Massman

2016-01-01

A one-dimensional vertical numerical model for coupled water flow and heat transport in soil and snow was modified to include all three phases of water: vapor, liquid, and ice. The top boundary condition in the model is driven by incoming precipitation and the surface energy balance. The model was applied to three different terrestrial systems: A warm desert bare...

WEB-DHM: A distributed biosphere hydrological model developed by coupling a simple biosphere scheme with a hillslope hydrological model

USDA-ARS?s Scientific Manuscript database

The coupling of land surface models and hydrological models potentially improves the land surface representation, benefiting both the streamflow prediction capabilities as well as providing improved estimates of water and energy fluxes into the atmosphere. In this study, the simple biosphere model 2...

The Significant Surface-Water Connectivity of “Geographically Isolated Wetlands”

EPA Science Inventory

We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands b...

Constraining Water Vapor Abundance on Mars using a Coupled Heat-Water Transport Model and Seasonal Frost Observations

NASA Astrophysics Data System (ADS)

Bapst, J.; Byrne, S.

2016-12-01

The stability of water ice on Mars' surface is determined by its temperature and the density of water vapor at the bottom of the atmosphere. Multiple orbiting instruments have been used to study column-integrated water abundance in the martian atmosphere, resolving the global annual water cycle. However, poor knowledge of the vertical distribution of water makes constraining its abundance near the surface difficult. One must assume a mixing regime to produce surface vapor density estimates. More indirectly, one can use the appearance and disappearance of seasonal water frost, along with ice stability models, to estimate this value. Here, we use derived temperature and surface reflectance data from MGS TES to constrain a 1-D thermal diffusion model, which is coupled to an atmospheric water transport model. TES temperatures are used to constrain thermal properties of our modeled subsurface, while changes in TES albedo can be used to determine the timing of water frost. We tune the density of water vapor in the atmospheric model to match the observed seasonal water frost timing in the northern hemisphere, poleward of 45°N. Thus, we produce a new estimate for the water abundance in the lower atmosphere of Mars and how it varies seasonally and geographically. The timing of water frost can be ambiguous in TES data, especially at lower latitudes where the albedo contrast between frosted and unfrosted surfaces is lower (presumably due to lesser areal coverage of water frost). The uncertainty in frost timing with our approach is <20° LS ( 40 sols), and will be used to define upper and lower bounds in our estimate of vapor density. The implications of our derived vapor densities on the stability of surface and subsurface water ice will be discussed.

Modelling surface runoff and water fluxes over contrasted soils in pastoral Sahel: evaluation of the ALMIP2 land surface models over the Gourma region in Mali

USDA-ARS?s Scientific Manuscript database

Land surface processes play an important role in West African monsoon variability and land –atmosphere coupling has been shown to be particularly important in the Sahel. In addition, the evolution of hydrological systems in this region, and particularly the increase of surface water and runoff coeff...

Dynamics of two-dimensional monolayer water confined in hydrophobic and charged environments.

PubMed

Kumar, Pradeep; Han, Sungho

2012-09-21

We perform molecular dynamics simulations to study the effect of charged surfaces on the intermediate and long time dynamics of water in nanoconfinements. Here, we use the transferable interaction potential with five points (TIP5P) model of a water molecule confined in both hydrophobic and charged surfaces. For a single molecular layer of water between the surfaces, we find that the temperature dependence of the lateral diffusion constant of water up to very high temperatures remains Arrhenius with a high activation energy. In case of charged surfaces, however, the dynamics of water in the intermediate time regime is drastically modified presumably due to the transient coupling of dipoles of water molecules with electric field fluctuations induced by charges on the confining surfaces. Specifically, the lateral mean square displacements display a distinct super-diffusive behavior at intermediate time scale, defined as the time scale between ballistic and diffusive regimes. This change in the intermediate time-scale dynamics in the charged confinement leads to the enhancement of long-time dynamics as reflected in increasing diffusion constant. We introduce a simple model for a possible explanation of the super-diffusive behavior and find it to be in good agreement with our simulation results. Furthermore, we find that confinement and the surface polarity enhance the low frequency vibration in confinement compared to bulk water. By introducing a new effective length scale of coupling between translational and orientational motions, we find that the length scale increases with the increasing strength of the surface polarity. Further, we calculate the correlation between the diffusion constant and the excess entropy and find a disordering effect of polar surfaces on the structure of water. Finally, we find that the empirical relation between the diffusion constant and the excess entropy holds for a monolayer of water in nanoconfinement.

A simulation-optimization model for effective water resources management in the coastal zone

NASA Astrophysics Data System (ADS)

Spanoudaki, Katerina; Kampanis, Nikolaos

2015-04-01

Coastal areas are the most densely-populated areas in the world. Consequently water demand is high, posing great pressure on fresh water resources. Climatic change and its direct impacts on meteorological variables (e.g. precipitation) and indirect impact on sea level rise, as well as anthropogenic pressures (e.g. groundwater abstraction), are strong drivers causing groundwater salinisation and subsequently affecting coastal wetlands salinity with adverse effects on the corresponding ecosystems. Coastal zones are a difficult hydrologic environment to represent with a mathematical model due to the large number of contributing hydrologic processes and variable-density flow conditions. Simulation of sea level rise and tidal effects on aquifer salinisation and accurate prediction of interactions between coastal waters, groundwater and neighbouring wetlands requires the use of integrated surface water-groundwater mathematical models. In the past few decades several computer codes have been developed to simulate coupled surface and groundwater flow. However, most integrated surface water-groundwater models are based on the assumption of constant fluid density and therefore their applicability to coastal regions is questionable. Thus, most of the existing codes are not well-suited to represent surface water-groundwater interactions in coastal areas. To this end, the 3D integrated surface water-groundwater model IRENE (Spanoudaki et al., 2009; Spanoudaki, 2010) has been modified in order to simulate surface water-groundwater flow and salinity interactions in the coastal zone. IRENE, in its original form, couples the 3D shallow water equations to the equations describing 3D saturated groundwater flow of constant density. A semi-implicit finite difference scheme is used to solve the surface water flow equations, while a fully implicit finite difference scheme is used for the groundwater equations. Pollution interactions are simulated by coupling the advection-diffusion equation describing the fate and transport of contaminants introduced in a 3D turbulent flow field to the partial differential equation describing the fate and transport of contaminants in 3D transient groundwater flow systems. The model has been further developed to include the effects of density variations on surface water and groundwater flow, while the already built-in solute transport capabilities are used to simulate salinity interactions. The refined model is based on the finite volume method using a cell-centred structured grid, providing thus flexibility and accuracy in simulating irregular boundary geometries. For addressing water resources management problems, simulation models are usually externally coupled with optimisation-based management models. However this usually requires a very large number of iterations between the optimisation and simulation models in order to obtain the optimal management solution. As an alternative approach, for improved computational efficiency, an Artificial Neural Network (ANN) is trained as an approximate simulator of IRENE. The trained ANN is then linked to a Genetic Algorithm (GA) based optimisation model for managing salinisation problems in the coastal zone. The linked simulation-optimisation model is applied to a hypothetical study area for performance evaluation. Acknowledgement The work presented in this paper has been funded by the Greek State Scholarships Foundation (IKY), Fellowships of Excellence for Postdoctoral Studies (Siemens Program), 'A simulation-optimization model for assessing the best practices for the protection of surface water and groundwater in the coastal zone', (2013 - 2015). References Spanoudaki, K., Stamou, A.I. and Nanou-Giannarou, A. (2009). Development and verification of a 3-D integrated surface water-groundwater model. Journal of Hydrology, 375 (3-4), 410-427. Spanoudaki, K. (2010). Integrated numerical modelling of surface water groundwater systems (in Greek). Ph.D. Thesis, National Technical University of Athens, Greece.

Mapping hydration dynamics and coupled water-protein fluctuations around a protein surface

NASA Astrophysics Data System (ADS)

Zhang, Luyuan; Wang, Lijuan; Kao, Ya-Ting; Qiu, Weihong; Yang, Yi; Okobiah, Oghaghare; Zhong, Dongping

2009-03-01

Elucidation of the molecular mechanism of water-protein interactions is critical to understanding many fundamental aspects of protein science, such as protein folding and misfolding and enzyme catalysis. We recently carried out a global mapping of protein-surface hydration dynamics around a globular α-helical protein apomyoglobin. The intrinsic optical probe tryptophan was employed to scan the protein surface one at a time by site-specific mutagenesis. With femtosecond resolution, we mapped out the dynamics of water-protein interactions with more than 20 mutants and for two states, native and molten globular. A robust bimodal distribution of time scales was observed, representing two types of water motions: local relaxation and protein-coupled fluctuations. The time scales show a strong correlation with the local protein structural rigidity and chemical identity. We also resolved two distinct contributions to the overall Stokes-shifts from the two time scales. These results are significant to understanding the role of hydration water on protein structural stability, dynamics and function.

A solid phase extraction-ion chromatography with conductivity detection procedure for determining cationic surfactants in surface water samples.

PubMed

Olkowska, Ewa; Polkowska, Żaneta; Namieśnik, Jacek

2013-11-15

A new analytical procedure for the simultaneous determination of individual cationic surfactants (alkyl benzyl dimethyl ammonium chlorides) in surface water samples has been developed. We describe this methodology for the first time: it involves the application of solid phase extraction (SPE-for sample preparation) coupled with ion chromatography-conductivity detection (IC-CD-for the final determination). Mean recoveries of analytes between 79% and 93%, and overall method quantification limits in the range from 0.0018 to 0.038 μg/mL for surface water and CRM samples were achieved. The methodology was applied to the determination of individual alkyl benzyl quaternary ammonium compounds in environmental samples (reservoir water) and enables their presence in such types of waters to be confirmed. In addition, it is a simpler, less time-consuming, labour-intensive, avoiding use of toxic chloroform and significantly less expensive methodology than previously described approaches (liquid-liquid extraction coupled with liquid chromatography-mass spectrometry). Copyright © 2013 Elsevier B.V. All rights reserved.

Surface models for coupled modelling of runoff and sewer flow in urban areas.

PubMed

Ettrich, N; Steiner, K; Thomas, M; Rothe, R

2005-01-01

Traditional methods fail for the purpose of simulating the complete flow process in urban areas as a consequence of heavy rainfall and as required by the European Standard EN-752 since the bi-directional coupling between sewer and surface is not properly handled. The new methodology, developed in the EUREKA-project RisUrSim, solves this problem by carrying out the runoff on the basis of shallow water equations solved on high-resolution surface grids. Exchange nodes between the sewer and the surface, like inlets and manholes, are located in the computational grid and water leaving the sewer in case of surcharge is further distributed on the surface. Dense topographical information is needed to build a model suitable for hydrodynamic runoff calculations; in urban areas, in addition, many line-shaped elements like houses, curbs, etc. guide the runoff of water and require polygonal input. Airborne data collection methods offer a great chance to economically gather densely sampled input data.

Assessing the performance of formulations for nonlinear feedback of surface gravity waves on ocean currents over coastal waters

NASA Astrophysics Data System (ADS)

Wang, Pengcheng; Sheng, Jinyu; Hannah, Charles

2017-08-01

This study presents applications of a two-way coupled wave-circulation modelling system over coastal waters, with a special emphasis of performance assessments of two different methods for nonlinear feedback of ocean surface gravity waves on three-dimensional (3D) ocean currents. These two methods are the vortex force (VF) formulation suggested by Bennis et al. (2011) and the latest version of radiation stress (RS) formulation suggested by Mellor (2015). The coupled modelling system is first applied to two idealized test cases of surf-zone scales to validate implementations of these two methods in the coupled wave-circulation system. Model results show that the latest version of RS has difficulties in producing the undertow over the surf zone. The coupled system is then applied to Lunenburg Bay (LB) of Nova Scotia during Hurricane Juan in 2003. The coupled system using both the VF and RS formulations generates much stronger and more realistic 3D circulation in the Bay during Hurricane Juan than the circulation-only model, demonstrating the importance of surface wave forces to the 3D ocean circulation over coastal waters. However, the RS formulation generates some weak unphysical currents outside the wave breaking zone due to a less reasonable representation for the vertical distribution of the RS gradients over a slopping bottom. These weak unphysical currents are significantly magnified in a two-way coupled system when interacting with large surface waves, degrading the model performance in simulating currents at one observation site. Our results demonstrate that the VF formulation with an appropriate parameterization of wave breaking effects is able to produce reasonable results for applications over coastal waters during extreme weather events. The RS formulation requires a complex wave theory rather than the linear wave theory for the approximation of a vertical RS term to improve its performance under both breaking and non-breaking wave conditions.

Robust Representation of Integrated Surface-subsurface Hydrology at Watershed Scales

NASA Astrophysics Data System (ADS)

Painter, S. L.; Tang, G.; Collier, N.; Jan, A.; Karra, S.

2015-12-01

A representation of integrated surface-subsurface hydrology is the central component to process-rich watershed models that are emerging as alternatives to traditional reduced complexity models. These physically based systems are important for assessing potential impacts of climate change and human activities on groundwater-dependent ecosystems and water supply and quality. Integrated surface-subsurface models typically couple three-dimensional solutions for variably saturated flow in the subsurface with the kinematic- or diffusion-wave equation for surface flows. The computational scheme for coupling the surface and subsurface systems is key to the robustness, computational performance, and ease-of-implementation of the integrated system. A new, robust approach for coupling the subsurface and surface systems is developed from the assumption that the vertical gradient in head is negligible at the surface. This tight-coupling assumption allows the surface flow system to be incorporated directly into the subsurface system; effects of surface flow and surface water accumulation are represented as modifications to the subsurface flow and accumulation terms but are not triggered until the subsurface pressure reaches a threshold value corresponding to the appearance of water on the surface. The new approach has been implemented in the highly parallel PFLOTRAN (www.pflotran.org) code. Several synthetic examples and three-dimensional examples from the Walker Branch Watershed in Oak Ridge TN demonstrate the utility and robustness of the new approach using unstructured computational meshes. Representation of solute transport in the new approach is also discussed. Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes.

Simulation of groundwater and surface-water resources of the Santa Rosa Plain watershed, Sonoma County, California

USGS Publications Warehouse

Woolfenden, Linda R.; Nishikawa, Tracy

2014-01-01

Water managers in the Santa Rosa Plain face the challenge of meeting increasing water demand with a combination of Russian River water, which has uncertainties in its future availability; local groundwater resources; and ongoing and expanding recycled water and water from other conservation programs. To address this challenge, the U.S. Geological Survey, in cooperation with the Sonoma County Water Agency, the cities of Cotati, Rohnert Park, Santa Rosa, and Sebastopol, the town of Windsor, the California American Water Company, and the County of Sonoma, undertook development of a fully coupled groundwater and surface-water model to better understand and to help manage the hydrologic resources in the Santa Rosa Plain watershed. The purpose of this report is to (1) describe the construction and calibration of the fully coupled groundwater and surface-water flow model for the Santa Rosa Plain watershed, referred to as the Santa Rosa Plain hydrologic model; (2) present results from simulation of the Santa Rosa Plain hydrologic model, including water budgets, recharge distributions, streamflow, and the effect of pumping on water-budget components; and (3) present the results from using the model to evaluate the potential hydrologic effects of climate change and variability without pumpage for water years 2011-99 and with projected pumpage for water years 2011-40.

Determination of glyphosate and AMPA in surface and waste water using high-performance ion chromatography coupled to inductively coupled plasma dynamic reaction cell mass spectrometry (HPIC-ICP-DRC-MS).

PubMed

Popp, Maximilian; Hann, Stephan; Mentler, Axel; Fuerhacker, Maria; Stingeder, Gerhard; Koellensperger, Gunda

2008-05-01

A novel method employing high-performance cation chromatography in combination with inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) for the simultaneous determination of the herbicide glyphosate (N-phosphonomethylglycine) and its main metabolite aminomethyl phosphonic acid (AMPA) is presented. P was measured as (31)P(16)O(+) using oxygen as reaction gas. For monitoring the stringent target value of 0.1 μg L(-1) for glyphosate, applicable for drinking and surface water within the EU, a two-step enrichment procedure employing Chelex 100 and AG1-X8 resins was applied prior to HPIC-ICP-MS analysis. The presented approach was validated for surface water, revealing concentrations of 0.67 μg L(-1) glyphosate and 2.8 μg L(-1) AMPA in selected Austrian river water samples. Moreover, investigations at three waste water-treatment plants showed that elimination of the compounds at the present concentration levels was not straightforward. On the contrary, all investigated plant effluents showed significant amounts of both compounds. Concentration levels ranged from 0.5-2 μg L(-1) and 4-14 μg L(-1) for glyphosate and AMPA, respectively.

First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach

USGS Publications Warehouse

Ebel, B.A.; Mirus, B.B.; Heppner, C.S.; VanderKwaak, J.E.; Loague, K.

2009-01-01

Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface-subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first-order exchange coefficients at a well-characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first-order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first-order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept-development simulations to examine real-world situations where the surface-subsurface exchange is impaired. While the parameters comprising the first-order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first-order exchange coefficient approach can be consistent with a physics-based framework. Copyright ?? 2009 John Wiley & Sons, Ltd.

Modeling large-scale human alteration of land surface hydrology and climate

NASA Astrophysics Data System (ADS)

Pokhrel, Yadu N.; Felfelani, Farshid; Shin, Sanghoon; Yamada, Tomohito J.; Satoh, Yusuke

2017-12-01

Rapidly expanding human activities have profoundly affected various biophysical and biogeochemical processes of the Earth system over a broad range of scales, and freshwater systems are now amongst the most extensively altered ecosystems. In this study, we examine the human-induced changes in land surface water and energy balances and the associated climate impacts using a coupled hydrological-climate model framework which also simulates the impacts of human activities on the water cycle. We present three sets of analyses using the results from two model versions—one with and the other without considering human activities; both versions are run in offline and coupled mode resulting in a series of four experiments in total. First, we examine climate and human-induced changes in regional water balance focusing on the widely debated issue of the desiccation of the Aral Sea in central Asia. Then, we discuss the changes in surface temperature as a result of changes in land surface energy balance due to irrigation over global and regional scales. Finally, we examine the global and regional climate impacts of increased atmospheric water vapor content due to irrigation. Results indicate that the direct anthropogenic alteration of river flow in the Aral Sea basin resulted in the loss of 510 km3 of water during the latter half of the twentieth century which explains about half of the total loss of water from the sea. Results of irrigation-induced changes in surface energy balance suggest a significant surface cooling of up to 3.3 K over 1° grids in highly irrigated areas but a negligible change in land surface temperature when averaged over sufficiently large global regions. Results from the coupled model indicate a substantial change in 2 m air temperature and outgoing longwave radiation due to irrigation, highlighting the non-local (regional and global) implications of irrigation. These results provide important insights on the direct human alteration of land surface water and energy balances, highlighting the need to incorporate human activities such as irrigation into the framework of global climate models and Earth system models for better prediction of future changes under increasing human influence and continuing global climate change.

A New Scheme for Considering Soil Water-Heat Transport Coupling Based on Community Land Model: Model Description and Preliminary Validation

NASA Astrophysics Data System (ADS)

Wang, Chenghai; Yang, Kai

2018-04-01

Land surface models (LSMs) have developed significantly over the past few decades, with the result that most LSMs can generally reproduce the characteristics of the land surface. However, LSMs fail to reproduce some details of soil water and heat transport during seasonal transition periods because they neglect the effects of interactions between water movement and heat transfer in the soil. Such effects are critical for a complete understanding of water-heat transport within a soil thermohydraulic regime. In this study, a fully coupled water-heat transport scheme (FCS) is incorporated into the Community Land Model (version 4.5) to replaces its original isothermal scheme, which is more complete in theory. Observational data from five sites are used to validate the performance of the FCS. The simulation results at both single-point and global scale show that the FCS improved the simulation of soil moisture and temperature. FCS better reproduced the characteristics of drier and colder surface layers in arid regions by considering the diffusion of soil water vapor, which is a nonnegligible process in soil, especially for soil surface layers, while its effects in cold regions are generally inverse. It also accounted for the sensible heat fluxes caused by liquid water flow, which can contribute to heat transfer in both surface and deep layers. The FCS affects the estimation of surface sensible heat (SH) and latent heat (LH) and provides the details of soil heat and water transportation, which benefits to understand the inner physical process of soil water-heat migration.

Chemical composition of natural waters of contaminated area: The case for the Imandra Lake catchment (the Kola Peninsula)

NASA Astrophysics Data System (ADS)

Evtyugina, Z. A.; Guseva, N. V.; Kopylova, J. G.; A, Vorobeva D.

2016-03-01

The study of the current chemical composition of natural waters in the eastern and western parts of the Imandra Lake catchment was performed using ion chromatography, potentiometry and inductively coupled plasma mass spectrometry. It was found that the content of trace elements in the surface water is considerably higher than that in the groundwater. The nickel and copper concentrations exceed the background levels over 19 and 2 times respectively in groundwater, and 175 and 61 times in the surface waters. These data show that the Severonikel influences negatively air and surface water.

Cross-compartment evaluation of a fully-coupled hydrometeorological modeling system using comprehensive observation data

NASA Astrophysics Data System (ADS)

Fersch, Benjamin; Senatore, Alfonso; Kunstmann, Harald

2017-04-01

Fully-coupled hydrometeorological modeling enables investigations about the complex and often non-linear exchange mechanisms among subsurface, land, and atmosphere with respect to water and energy fluxes. The consideration of lateral redistribution of surface and subsurface water in such modeling systems is a crucial enhancement, allowing for a better representation of surface spatial patterns and providing also channel discharge predictions. However, the evaluation of fully-coupled simulations is difficult since the amount of physical detail along with feedback mechanisms leads to high degrees of freedom. Therefore, comprehensive observation data is required to obtain meaningful model configurations. We present a case study for a medium-sized river catchment in southern Germany that includes the calibration of the stand-alone and the evaluation of the fully-coupled WRF-Hydro modeling system with a horizontal resolution of 1 x 1 km2, for the period June to August 2015. ECMWF ERA-Interim reanalysis is used for model driving. Land-surface processes are represented by the Noah-MP land surface model. Land-cover is described by the EU CORINE data set. Observations for model evaluation are obtained from the TERENO Pre-Alpine observatory (http://www.imk-ifu.kit.edu/tereno.php) and are complemented by further measurements from the ScaleX campaign (http://scalex.imk-ifu.kit.edu) such as atmospheric profiles obtained from radiometer sounding and airborne systems as well as soil moisture and -temperature networks. We show how well water budgets and heat-fluxes are being reproduced by the stand-alone WRF, the stand-alone WRF-Hydro and the fully-coupled WRF-Hydro model.

Application of gas-coupled laser acoustic detection to gelatins and underwater sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caron, James N.; Kunapareddy, Pratima

2014-02-18

Gas-coupled Laser Acoustic Detection (GCLAD) has been used as a method to sense ultrasound waves in materials without contact of the material surface. To sense the waveform, a laser beam is directed parallel to the material surface and displaced or deflected when the radiated waveform traverses the beam. We present recent tests that demonstrate the potential of using this technique for detecting ultrasound in gelatin phantoms and in water. As opposed to interferometric detection, GCLAD operates independently of the optical surface properties of the material. This allows the technique to be used in cases where the material is transparent ormore » semi-transparent. We present results on sensing ultrasound in gelatin phantoms that are used to mimic biological materials. As with air-coupled transducers, the frequency response of GCLAD at high frequencies is limited by the high attenuation of ultrasound in air. In contrast, water has a much lower attenuation. Here we demonstrate the use of a GCLAD-like system in water, measuring the directivity response at 1 MHz and sensing waveforms with higher frequency content.« less

Effects of the Extended Water Retention Curve on Coupled Heat and Water Transport in the Vadose Zone

NASA Astrophysics Data System (ADS)

Yang, Z.; Mohanty, B.

2017-12-01

Understanding and simulating coupled heat and water transfer appropriately in the shallow subsurface is of vital significance for accurate prediction of soil evaporation that would improve the coupling between land surface and atmosphere. The theory of Philip and de Vries (1957) and its extensions (de Vries, 1958; Milly, 1982), although physically incomplete, are still adopted successfully to describe the coupled heat and water movement in field soils. However, the adsorptive water retention, which was ignored in Philip and de Vries theory and its extensions for characterizing soil hydraulic parameters, was shown to be non-negligible for soil moisture and evaporation flux calculation in dry field soils based on a recent synthetic analysis (Mohanty and Yang, 2013). In this study, we attempt to comprehensively investigate the effects of full range water retention curve on coupled heat and water transport simulation with a focus on soil moisture content, temperature and soil evaporative flux, based on two synthetic (sand and loam) and two field sites (Riverside, California and Audubon, Arizona) analysis. The results of synthetic sand and loam numerical modeling showed that when neglecting the adsorptive water retention, the resulting simulated soil water content would be larger, and the evaporative flux would be lower, respectively, compared to that obtained by the full range water retention curve mode. The simulated temperature did not show significant difference with or without accounting for adsorptive water retention. The evaporation underestimation when neglecting the adsorptive water retention is mainly caused by isothermal hydraulic conductivity underprediction. These synthetic findings were further corroborated by the Audubon, Arizona field site experimental results. The results from Riverside, California field experimental site showed that the soil surface can reach very dry status, although the soil profile below the drying front is not dry, which also to some extent justifies the necessity of employing full range water retention function in such generally not quite dry scenarios.

Integrated Coupling of Surface and Subsurface Flow with HYDRUS-2D

NASA Astrophysics Data System (ADS)

Hartmann, Anne; Šimůnek, Jirka; Wöhling, Thomas; Schütze, Niels

2016-04-01

Describing interactions between surface and subsurface flow processes is important to adequately define water flow in natural systems. Since overland flow generation is highly influenced by rainfall and infiltration, both highly spatially heterogeneous processes, overland flow is unsteady and varies spatially. The prediction of overland flow needs to include an appropriate description of the interactions between the surface and subsurface flow. Coupling surface and subsurface water flow is a challenging task. Different approaches have been developed during the last few years, each having its own advantages and disadvantages. A new approach by Weill et al. (2009) to couple overland flow and subsurface flow based on a generalized Richards equation was implemented into the well-known subsurface flow model HYDRUS-2D (Šimůnek et al., 2011). This approach utilizes the one-dimensional diffusion wave equation to model overland flow. The diffusion wave model is integrated in HYDRUS-2D by replacing the terms of the Richards equation in a pre-defined runoff layer by terms defining the diffusion wave equation. Using this approach, pressure and flux continuity along the interface between both flow domains is provided. This direct coupling approach provides a strong coupling of both systems based on the definition of a single global system matrix to numerically solve the coupled flow problem. The advantage of the direct coupling approach, compared to the loosely coupled approach, is supposed to be a higher robustness, when many convergence problems can be avoided (Takizawa et al., 2014). The HYDRUS-2D implementation was verified using a) different test cases, including a direct comparison with the results of Weill et al. (2009), b) an analytical solution of the kinematic wave equation, and c) the results of a benchmark test of Maxwell et al. (2014), that included several known coupled surface subsurface flow models. Additionally, a sensitivity analysis evaluating the effects of various model parameters on simulated overland flow (while considering or neglecting the effects of subsurface flow) was carried out to verify the applicability of the model to different problems. The model produced reasonable results in describing the diffusion wave approximation and its interactions with subsurface flow processes. The model could handle coupled surface-subsurface processes for conditions involving runoff generated by infiltration excess, saturation excess, or run-on, as well as a combination of these runoff generating processes. Several standard features of the HYDRUS 2D model, such as root water uptake and evaporation from the soil surface, as well as evaporation from runoff layer, can still be considered by the new model. The code required relatively small time steps when overland flow was active, resulting in long simulation times, and sometimes produced poor mass balance. The model nevertheless showed potential to be a useful tool for addressing various issues related to irrigation research and to natural generation of overland flow at the hillslope scale. Maxwell, R., Putti, M., Meyerhoff, S., Delf, J., Ferguson, I., Ivanov, V., Kim, J., Kolditz, O., Kollet, S., Kumar, M., Lopez, S., Niu, J., Paniconi, C., Park, Y.-J., Phanikumar, M., Shen, C., Sudicky, E., and Sulis, M. (2014). Surface-subsurface model intercomparison: A first set of benchmark results to diagnose integrated hydrology and feedbacks. Water Resourc. Res., 50:1531-1549. Šimůnek, J., van Genuchten, M. T., and Šejna, M. (2011). The HYDRUS Software Package for Simulating Two- and Three-Dimensional Movement of Water, Heat, and Multiple Solutes in Variably-Saturated Media. Technical Manual, Version 2.0, PC Progress, Prague, Czech Republic. Takizawa, K., Bazilevs Y., Tezduyar, T. E., Long, C.C., Marsden, A. L. and Schjodt.K., Patient-Specific Cardiovascular Fluid Mechanics Analysis with the ST and ALE-VMS Method in Idelsohn, S. R. (2014). Numerical Simulations of Coupled Problems in Engineering. Springer. Weill, S., Mouche, E., and Patin, J. (2009). A generalized Richards equation for surface/subsurface flow modelling. Journal of Hydrology, 366:9-20.

Interlayer Water Regulates the Bio-nano Interface of a β-sheet Protein stacking on Graphene

PubMed Central

Lv, Wenping; Xu, Guiju; Zhang, Hongyan; Li, Xin; Liu, Shengju; Niu, Huan; Xu, Dongsheng; Wu, Ren'an

2015-01-01

Using molecular dynamics simulations, we investigated an integrated bio-nano interface consisting of a β-sheet protein stacked onto graphene. We found that the stacking assembly of the model protein on graphene could be controlled by water molecules. The interlayer water filled within interstices of the bio-nano interface could suppress the molecular vibration of surface groups on protein, and could impair the CH···π interaction driving the attraction of the protein and graphene. The intermolecular coupling of interlayer water would be relaxed by the relative motion of protein upon graphene due to the interaction between water and protein surface. This effect reduced the hindrance of the interlayer water against the assembly of protein on graphene, resulting an appropriate adsorption status of protein on graphene with a deep free energy trap. Thereby, the confinement and the relative sliding between protein and graphene, the coupling of protein and water, and the interaction between graphene and water all have involved in the modulation of behaviors of water molecules within the bio-nano interface, governing the hindrance of interlayer water against the protein assembly on hydrophobic graphene. These results provide a deep insight into the fundamental mechanism of protein adsorption onto graphene surface in water. PMID:25557857

Interlayer water regulates the bio-nano interface of a β-sheet protein stacking on graphene.

PubMed

Lv, Wenping; Xu, Guiju; Zhang, Hongyan; Li, Xin; Liu, Shengju; Niu, Huan; Xu, Dongsheng; Wu, Ren'an

2015-01-05

Using molecular dynamics simulations, we investigated an integrated bio-nano interface consisting of a β-sheet protein stacked onto graphene. We found that the stacking assembly of the model protein on graphene could be controlled by water molecules. The interlayer water filled within interstices of the bio-nano interface could suppress the molecular vibration of surface groups on protein, and could impair the CH···π interaction driving the attraction of the protein and graphene. The intermolecular coupling of interlayer water would be relaxed by the relative motion of protein upon graphene due to the interaction between water and protein surface. This effect reduced the hindrance of the interlayer water against the assembly of protein on graphene, resulting an appropriate adsorption status of protein on graphene with a deep free energy trap. Thereby, the confinement and the relative sliding between protein and graphene, the coupling of protein and water, and the interaction between graphene and water all have involved in the modulation of behaviors of water molecules within the bio-nano interface, governing the hindrance of interlayer water against the protein assembly on hydrophobic graphene. These results provide a deep insight into the fundamental mechanism of protein adsorption onto graphene surface in water.

Interlayer Water Regulates the Bio-nano Interface of a β-sheet Protein stacking on Graphene

NASA Astrophysics Data System (ADS)

Lv, Wenping; Xu, Guiju; Zhang, Hongyan; Li, Xin; Liu, Shengju; Niu, Huan; Xu, Dongsheng; Wu, Ren'an

2015-01-01

Using molecular dynamics simulations, we investigated an integrated bio-nano interface consisting of a β-sheet protein stacked onto graphene. We found that the stacking assembly of the model protein on graphene could be controlled by water molecules. The interlayer water filled within interstices of the bio-nano interface could suppress the molecular vibration of surface groups on protein, and could impair the CH...π interaction driving the attraction of the protein and graphene. The intermolecular coupling of interlayer water would be relaxed by the relative motion of protein upon graphene due to the interaction between water and protein surface. This effect reduced the hindrance of the interlayer water against the assembly of protein on graphene, resulting an appropriate adsorption status of protein on graphene with a deep free energy trap. Thereby, the confinement and the relative sliding between protein and graphene, the coupling of protein and water, and the interaction between graphene and water all have involved in the modulation of behaviors of water molecules within the bio-nano interface, governing the hindrance of interlayer water against the protein assembly on hydrophobic graphene. These results provide a deep insight into the fundamental mechanism of protein adsorption onto graphene surface in water.

Fully coupled six-dimensional calculations of the water dimer vibration-rotation-tunneling states with split Wigner pseudospectral approach. II. Improvements and tests of additional potentials

NASA Astrophysics Data System (ADS)

Fellers, R. S.; Braly, L. B.; Saykally, R. J.; Leforestier, C.

1999-04-01

The SWPS method is improved by the addition of H.E.G. contractions for generating a more compact basis. An error in the definition of the internal fragment axis system used in our previous calculation is described and corrected. Fully coupled 6D (rigid monomers) VRT states are computed for several new water dimer potential surfaces and compared with experiment and our earlier SWPS results. This work sets the stage for refinement of such potential surfaces via regression analysis of VRT spectroscopic data.

Development of a Coupled Hydrological/Sediment Yield Model for a Watershed at Regional Level

NASA Technical Reports Server (NTRS)

Rajbhandaril, Narayan; Crosson, William; Tsegaye, Teferi; Coleman, Tommy; Liu, Yaping; Soman, Vishwas

1998-01-01

Development of a hydrologic model for the study of environmental conservation requires a comprehensive understanding of individual-storm affecting hydrologic and sedimentologic processes. The hydrologic models that we are currently coupling are the Simulator for Hydrology and Energy Exchange at the Land Surface (SHEELS) and the Distributed Runoff Model (DRUM). SHEELS runs continuously to estimate surface energy fluxes and sub-surface soil water fluxes, while DRUM operates during and following precipitation events to predict surface runoff and peak flow through channel routing. The lateral re-distribution of surface water determined by DRUM is passed to SHEELS, which then adjusts soil water contents throughout the profile. The model SHEELS is well documented in Smith et al. (1993) and Laymen and Crosson (1995). The model DRUM is well documented in Vieux et al. (1990) and Vieux and Gauer (1994). The coupled hydrologic model, SHEELS/DRUM, does not simulate sedimentologic processes. The simulation of the sedimentologic process is important for environmental conservation planning and management. Therefore, we attempted to develop a conceptual frame work for coupling a sediment yield model with SHEELS/DRUM to estimate individual-storm sediment yield from a watershed at a regional level. The sediment yield model that will be used for this study is the Universal Soil Loss Equation (USLE) with some modifications to enable the model to predict individual-storm sediment yield. The predicted sediment yield does not include wind erosion and erosion caused by irrigation and snow melt. Units used for this study are those given by Foster et al. (1981) for SI units.

A Bayesian Framework for Coupled Estimation of Key Unknown Parameters of Land Water and Energy Balance Equations

NASA Astrophysics Data System (ADS)

Farhadi, L.; Abdolghafoorian, A.

2015-12-01

The land surface is a key component of climate system. It controls the partitioning of available energy at the surface between sensible and latent heat, and partitioning of available water between evaporation and runoff. Water and energy cycle are intrinsically coupled through evaporation, which represents a heat exchange as latent heat flux. Accurate estimation of fluxes of heat and moisture are of significant importance in many fields such as hydrology, climatology and meteorology. In this study we develop and apply a Bayesian framework for estimating the key unknown parameters of terrestrial water and energy balance equations (i.e. moisture and heat diffusion) and their uncertainty in land surface models. These equations are coupled through flux of evaporation. The estimation system is based on the adjoint method for solving a least-squares optimization problem. The cost function consists of aggregated errors on state (i.e. moisture and temperature) with respect to observation and parameters estimation with respect to prior values over the entire assimilation period. This cost function is minimized with respect to parameters to identify models of sensible heat, latent heat/evaporation and drainage and runoff. Inverse of Hessian of the cost function is an approximation of the posterior uncertainty of parameter estimates. Uncertainty of estimated fluxes is estimated by propagating the uncertainty for linear and nonlinear function of key parameters through the method of First Order Second Moment (FOSM). Uncertainty analysis is used in this method to guide the formulation of a well-posed estimation problem. Accuracy of the method is assessed at point scale using surface energy and water fluxes generated by the Simultaneous Heat and Water (SHAW) model at the selected AmeriFlux stations. This method can be applied to diverse climates and land surface conditions with different spatial scales, using remotely sensed measurements of surface moisture and temperature states

Documentation of a restart option for the U.S. Geological Survey coupled Groundwater and Surface-Water Flow (GSFLOW) model

USGS Publications Warehouse

Regan, R. Steve; Niswonger, Richard G.; Markstrom, Steven L.; Barlow, Paul M.

2015-10-02

The spin-up simulation should be run for a sufficient length of time necessary to establish antecedent conditions throughout a model domain. Each GSFLOW application can require different lengths of time to account for the hydrologic stresses to propagate through a coupled groundwater and surface-water system. Typically, groundwater hydrologic processes require many years to come into equilibrium with dynamic climate and other forcing (or stress) data, such as precipitation and well pumping, whereas runoff-dominated surface-water processes respond relatively quickly. Use of a spin-up simulation can substantially reduce execution-time requirements for applications where the time period of interest is small compared to the time for hydrologic memory; thus, use of the restart option can be an efficient strategy for forecast and calibration simulations that require multiple simulations starting from the same day.

Simulation of climate-change effects on streamflow, lake water budgets, and stream temperature using GSFLOW and SNTEMP, Trout Lake Watershed, Wisconsin

USGS Publications Warehouse

Hunt, Randall J.; Walker, John F.; Selbig, William R.; Westenbroek, Stephen M.; Regan, R. Steve

2013-01-01

Although groundwater and surface water are considered a single resource, historically hydrologic simulations have not accounted for feedback loops between the groundwater system and other hydrologic processes. These feedbacks include timing and rates of evapotranspiration, surface runoff, soil-zone flow, and interactions with the groundwater system. Simulations that iteratively couple the surface-water and groundwater systems, however, are characterized by long run times and calibration challenges. In this study, calibrated, uncoupled transient surface-water and steady-state groundwater models were used to construct one coupled transient groundwater/surface-water model for the Trout Lake Watershed in north-central Wisconsin, USA. The computer code GSFLOW (Ground-water/Surface-water FLOW) was used to simulate the coupled hydrologic system; a surface-water model represented hydrologic processes in the atmosphere, at land surface, and within the soil-zone, and a groundwater-flow model represented the unsaturated zone, saturated zone, stream, and lake budgets. The coupled GSFLOW model was calibrated by using heads, streamflows, lake levels, actual evapotranspiration rates, solar radiation, and snowpack measurements collected during water years 1998–2007; calibration was performed by using advanced features present in the PEST parameter estimation software suite. Simulated streamflows from the calibrated GSFLOW model and other basin characteristics were used as input to the one-dimensional SNTEMP (Stream-Network TEMPerature) model to simulate daily stream temperature in selected tributaries in the watershed. The temperature model was calibrated to high-resolution stream temperature time-series data measured in 2002. The calibrated GSFLOW and SNTEMP models were then used to simulate effects of potential climate change for the period extending to the year 2100. An ensemble of climate models and emission scenarios was evaluated. Downscaled climate drivers for the period 2010–2100 showed increases in maximum and minimum temperature over the scenario period. Scenarios of future precipitation did not show a monotonic trend like temperature. Uncertainty in the climate drivers increased over time for both temperature and precipitation. Separate calibration of the uncoupled groundwater and surface-water models did not provide a representative initial parameter set for coupled model calibration. A sequentially linked calibration, in which the uncoupled models were linked by means of utility software, provided a starting parameter set suitable for coupled model calibration. Even with sequentially linked calibration, however, transmissivity of the lower part of the aquifer required further adjustment during coupled model calibration to attain reasonable parameter values for evaporation rates off a small seepage lake (a lake with no appreciable surface-water outlets) with a long history of study. The resulting coupled model was well calibrated to most types of observed time-series data used for calibration. Daily stream temperatures measured during 2002 were successfully simulated with SNTEMP; the model fit was acceptable for a range of groundwater inflow rates into the streams. Forecasts of potential climate change scenarios showed growing season length increasing by weeks, and both potential and actual evapotranspiration rates increasing appreciably, in response to increasing air temperature. Simulated actual evapotranspiration rates increased less than simulated potential evapotranspiration rates as a result of water limitation in the root zone during the summer high-evapotranspiration period. The hydrologic-system response to climate change was characterized by a reduction in the importance of the snow-melt pulse and an increase in the importance of fall and winter groundwater recharge. The less dynamic hydrologic regime is likely to result in drier soil conditions in rainfed wetlands and uplands, in contrast to less drying in groundwater-fed systems. Seepage lakes showed larger forecast stage declines related to climate change than did drainage lakes (lakes with outlet streams). Seepage lakes higher in the watershed (nearer to groundwater divides) had less groundwater inflow and thus had larger forecast declines in lake stage; however, ground-water inflow to seepage lakes in general tended to increase as a fraction of the lake budgets with lake-stage decline because inward hydraulic gradients increased. Drainage lakes were characterized by less simulated stage decline as reductions in outlet streamflow of set losses to other water flows. Net groundwater inflow tended to decrease in drainage lakes over the scenario period. Simulated stream temperatures increased appreciably with climate change. The estimated increase in annual average temperature ranged from approximately 1 to 2 degrees Celsius by 2100 in the stream characterized by a high groundwater inflow rate and 2 to 3 degrees Celsius in the stream with a lower rate. The climate drivers used for the climate-change scenarios had appreciable variation between the General Circulation Model and emission scenario selected; this uncertainty was reflected in hydrologic flow and temperature model results. Thus, as with all forecasts of this type, the results are best considered to approximate potential outcomes of climate change.

Hydrogeochemical zonation in intertidal salt marsh sediments: evidence of positive plant-soil feedback?

NASA Astrophysics Data System (ADS)

Moffett, K. B.; Dittmar, J.; Seyfferth, A.; Fendorf, S.; Gorelick, S.

2012-12-01

Surface and subsurface environments are linked by the biogeochemical activity in near-surface sediment and by the hydrological fluxes that mobilize its reagents and products. A particularly dynamic and interesting setting to study near-surface hydrogeochemistry is the intertidal zone. Here, the very strong tidal hydraulic forcing is often thought to dominate water and solute transport. However, we demonstrated the importance of two additional subsurface drivers: groundwater flow and plant root water uptake. A high-resolution, coupled surface water-groundwater model of an intertidal salt marsh in San Francisco Bay, CA showed that these three drivers vary over different spatial scales: tidal flooding varies over 10's of meters; groundwater flow varies over meters, particularly within channel banks; and plant root water uptake varies in 3D at the sub-meter scale. Expanding on this third driver, we investigated whether the spatial variations in soil-water-plant hydraulic interactions that occur due to vegetation zonation also cause distinct geochemical zonation in salt marsh sediment pore waters. The existence of such geochemical zonation was verified and mapped by detailed field observations of the chemical composition of sediments, pore waters, surface waters, and vegetation. The field data and the coupled hydrologic model were then further analyzed to evaluate potential causal mechanisms for the geochemical zonation, including testing the hypothesis that the vegetation affects pore water geochemistry via a positive feedback beneficial to itself. If further supported by future studies, this geochemical feedback may complement known physical ecosystem engineering mechanisms to help stabilize and organize intertidal wetlands.

Drogue performance evaluation. Part 1: Data acquisition. [for accurate description of subsurface water circulation

NASA Technical Reports Server (NTRS)

Johnson, R. E.

1975-01-01

Surface buoy/subsurface drogue drag coupling was investigated. Data acquisition methods and techniques derived from several experimental cruises on the Chesapeake Bay are presented. Four buoys were utilized: three coupled to steel plates rigidly attached to each other at right angles and at various depths; and one spar type that did not require drag plates. Data from these surface floats and the drogue depth combinations were processed. Errors in tracking the surface buoys are discussed.

The SURFEXv7.2 land and ocean surface platform for coupled or offline simulation of earth surface variables and fluxes

NASA Astrophysics Data System (ADS)

Masson, V.; Le Moigne, P.; Martin, E.; Faroux, S.; Alias, A.; Alkama, R.; Belamari, S.; Barbu, A.; Boone, A.; Bouyssel, F.; Brousseau, P.; Brun, E.; Calvet, J.-C.; Carrer, D.; Decharme, B.; Delire, C.; Donier, S.; Essaouini, K.; Gibelin, A.-L.; Giordani, H.; Habets, F.; Jidane, M.; Kerdraon, G.; Kourzeneva, E.; Lafaysse, M.; Lafont, S.; Lebeaupin Brossier, C.; Lemonsu, A.; Mahfouf, J.-F.; Marguinaud, P.; Mokhtari, M.; Morin, S.; Pigeon, G.; Salgado, R.; Seity, Y.; Taillefer, F.; Tanguy, G.; Tulet, P.; Vincendon, B.; Vionnet, V.; Voldoire, A.

2013-07-01

SURFEX is a new externalized land and ocean surface platform that describes the surface fluxes and the evolution of four types of surfaces: nature, town, inland water and ocean. It is mostly based on pre-existing, well-validated scientific models that are continuously improved. The motivation for the building of SURFEX is to use strictly identical scientific models in a high range of applications in order to mutualise the research and development efforts. SURFEX can be run in offline mode (0-D or 2-D runs) or in coupled mode (from mesoscale models to numerical weather prediction and climate models). An assimilation mode is included for numerical weather prediction and monitoring. In addition to momentum, heat and water fluxes, SURFEX is able to simulate fluxes of carbon dioxide, chemical species, continental aerosols, sea salt and snow particles. The main principles of the organisation of the surface are described first. Then, a survey is made of the scientific module (including the coupling strategy). Finally, the main applications of the code are summarised. The validation work undertaken shows that replacing the pre-existing surface models by SURFEX in these applications is usually associated with improved skill, as the numerous scientific developments contained in this community code are used to good advantage.

Modeling Coupled Movement of Water, Vapor, and Energy in Soils and at the Soil-Atmosphere Interface Using HYDRUS

NASA Astrophysics Data System (ADS)

Simunek, Jiri; Brunetti, Giuseppe; Saito, Hirotaka; Bristow, Keith

2017-04-01

Mass and energy fluxes in the subsurface are closely coupled and cannot be evaluated without considering their mutual interactions. However, only a few numerical models consider coupled water, vapor and energy transport in both the subsurface and at the soil-atmosphere interface. While hydrological and thermal processes in the subsurface are commonly implemented in existing models, which often consider both isothermally and thermally induced water and vapor flow, the interactions at the soil-atmosphere interface are often simplified, and the effects of slope inclination, slope azimuth, variable surface albedo and plant shading on incoming radiation and spatially variable surface mass and energy balance, and consequently on soil moisture and temperature distributions, are rarely considered. In this presentation we discuss these missing elements and our attempts to implement them into the HYDRUS model. We demonstrate implications of some of these interactions and their impact on the spatial distributions of soil temperature and water content, and their effect on soil evaporation. Additionally, we will demonstrate the use of the HYDRUS model to simulate processes relevant to the ground source heat pump systems.

Applying the Coupled-Cluster Ansatz to Solids and Surfaces in the Thermodynamic Limit

NASA Astrophysics Data System (ADS)

Gruber, Thomas; Liao, Ke; Tsatsoulis, Theodoros; Hummel, Felix; Grüneis, Andreas

2018-04-01

Modern electronic structure theories can predict and simulate a wealth of phenomena in surface science and solid-state physics. In order to allow for a direct comparison with experiment, such ab initio predictions have to be made in the thermodynamic limit, substantially increasing the computational cost of many-electron wave-function theories. Here, we present a method that achieves thermodynamic limit results for solids and surfaces using the "gold standard" coupled cluster ansatz of quantum chemistry with unprecedented efficiency. We study the energy difference between carbon diamond and graphite crystals, adsorption energies of water on h -BN, as well as the cohesive energy of the Ne solid, demonstrating the increased efficiency and accuracy of coupled cluster theory for solids and surfaces.

A prototype data assimilation framework for generating spatiotemporally continuous SWOT data products

NASA Astrophysics Data System (ADS)

Andreadis, K.; Margulis, S. A.; Li, D.; Lettenmaier, D. P.

2017-12-01

The Surface Water and Ocean Topography (SWOT) satellite will provide critical surface water observations for the hydrologic community. However, production of key SWOT variables, such as river discharge and surface inundation, as well as lake, reservoir, and wetland storage change will be complicated by the discontinuity of the observations in space and time. A methodology that generates products with spatially and temporally continuous fields based on SWOT observables would be highly desirable. Data assimilation provides a mechanism for merging observations from SWOT with model predictions in order to produce estimates of quantities such as river discharge, storage change, and water heights for locations and times when there is no satellite overpass or other constraints (such as layover) render the measurement unusable. We describe here a prototype assimilation system with application to the Upper Mississippi basin, implemented using synthetic SWOT observations. We use a hydrologic model (VIC) coupled with a hydrodynamic model (LISFLOOD-FP) which generates "true" fields of surface water variables. The true fields are then used to generate synthetic SWOT observations using the SWOT Instrument Simulator. We also perform a "first-guess" (or open-loop) simulation with the coupled model using a configuration that contains errors representative of the imperfect knowledge of parameters and input data, including channel topography, bankfull widths and depths, and inflows, to create an ensemble of 20 model trajectories. Subsequently we assimilate the synthetic SWOT observations into the open-loop model results to estimate water surface elevation, discharge, and storage change. Our preliminary results using three data assimilation strategies show that all improve the water surface elevation estimate accuracy by 25% - 35% for a river reach of the upper Mississippi River. Ongoing work is examining whether the improved water surface elevation estimates propagate to improvements in river discharge.

Blueprint for a coupled model of sedimentology, hydrology, and hydrogeology in streambeds

NASA Astrophysics Data System (ADS)

Partington, Daniel; Therrien, Rene; Simmons, Craig T.; Brunner, Philip

2017-06-01

The streambed constitutes the physical interface between the surface and the subsurface of a stream. Across all spatial scales, the physical properties of the streambed control surface water-groundwater interactions. Continuous alteration of streambed properties such as topography or hydraulic conductivity occurs through erosion and sedimentation processes. Recent studies from the fields of ecology, hydrogeology, and sedimentology provide field evidence that sedimentological processes themselves can be heavily influenced by surface water-groundwater interactions, giving rise to complex feedback mechanisms between sedimentology, hydrology, and hydrogeology. More explicitly, surface water-groundwater exchanges play a significant role in the deposition of fine sediments, which in turn modify the hydraulic properties of the streambed. We explore these feedback mechanisms and critically review the extent of current interaction between the different disciplines. We identify opportunities to improve current modeling practices. For example, hydrogeological models treat the streambed as a static rather than a dynamic entity, while sedimentological models do not account for critical catchment processes such as surface water-groundwater exchange. We propose a blueprint for a new modeling framework that bridges the conceptual gaps between sedimentology, hydrogeology, and hydrology. Specifically, this blueprint (1) fully integrates surface-subsurface flows with erosion, transport, and deposition of sediments and (2) accounts for the dynamic changes in surface elevation and hydraulic conductivity of the streambed. Finally, we discuss the opportunities for new research within the coupled framework.

Simulation of Wave-Current Interaction Using a Three-Dimensional Hydrodynamic Model Coupled With a Phase Averaged Wave Model

NASA Astrophysics Data System (ADS)

Marsooli, R.; Orton, P. M.; Georgas, N.; Blumberg, A. F.

2016-02-01

The Stevens Institute of Technology Estuarine and Coastal Ocean Model (sECOM) has been coupled with a more advanced surface wave model to simulate wave‒current interaction, and results have been validated in estuarine and nearshore waters. sECOM is a three‒dimensional, hydrostatic, free surface, primitive equation model. It solves the Navier‒Stokes equations and the conservation equations for temperature and salinity using a finite‒difference method on an Arakawa C‒grid with a terrain‒following (sigma) vertical coordinate and orthogonal curvilinear horizontal coordinate system. The model is coupled with the surface wave model developed by Mellor et al. (2008), which solves the spectral equation and takes into account depth and current refraction, and deep and shallow water. The wave model parameterizes the energy distribution in frequency space and the wave‒wave interaction process by using a specified spectrum shape. The coupled wave‒hydrodynamic model considers the wave‒current interaction through wave‒induced bottom stress, depth‒dependent radiation stress, and wave effects on wind‒induced surface stress. The model is validated using the data collected at a natural sandy beach at Duck, North Carolina, during the DUCK94 experiment. This test case reveals the capability of the model to simulate the wave‒current interaction in nearshore coastal systems. The model is further validated using the data collected in Jamaica Bay, a semi‒enclosed body of water located in New York City region. This test reveals the applicability of the model to estuarine systems. These validations of the model and comparisons to its prior wave model, the Great Lakes Environmental Research Laboratory (GLERL) wave model (Donelan 1977), are presented and discussed. ReferencesG.L. Mellor, M.A. Donelan, and L‒Y. Oey, 2008, A Surface Wave Model for Coupling with Numerical Ocean Circulation Models. J. Atmos. Oceanic Technol., 25, 1785‒1807.Donelan, M. A 1977. A simple numerical model for wave and wind stress application. Report, National Water Research Institute, Burlington, Ontario, Canada, 28 pp.

Modeling interactions of agriculture and groundwater nitrate contaminants: application of The STICS-Eau-Dyssée coupled models over the Seine River Basin

NASA Astrophysics Data System (ADS)

Tavakoly, A. A.; Habets, F.; Saleh, F.; Yang, Z. L.

2017-12-01

Human activities such as the cultivation of N-fixing crops, burning of fossil fuels, discharging of industrial and domestic effluents, and extensive usage of fertilizers have recently accelerated the nitrogen loading to watersheds worldwide. Increasing nitrate concentration in surface water and groundwater is a major concern in watersheds with extensive agricultural activities. Nutrient enrichment is one of the major environmental problems in the French coastal zone. To understand and predict interactions between agriculture, surface water and groundwater nitrate contaminants, this study presents a modeling framework that couples the agronomic STICS model with Eau-Dyssée, a distributed hydrologic modeling system to simulate groundwater-surface water interaction. The coupled system is implemented on the Seine River Basin with an area of 88,000 km2 to compute daily nitrate contaminants. Representing a sophisticated hydrosystem with several aquifers and including the megalopolis of Paris, the Seine River Basin is well-known as one of the most productive agricultural areas in France. The STICS-EauDyssée framework is evaluated for a long-term simulation covering 39 years (1971-2010). Model results show that the simulated nitrate highly depends on the inflow produced by surface and subsurface waters. Daily simulation shows that the model captures the seasonal variation of observations and that the overall long-term simulation of nitrate contaminant is satisfactory at the regional scale.

Fully coupled six-dimensional calculations of the water dimer vibration-rotation-tunneling states with split Wigner pseudospectral approach. II. Improvements and tests of additional potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fellers, R.S.; Braly, L.B.; Saykally, R.J.

The SWPS method is improved by the addition of H.E.G. contractions for generating a more compact basis. An error in the definition of the internal fragment axis system used in our previous calculation is described and corrected. Fully coupled 6D (rigid monomers) VRT states are computed for several new water dimer potential surfaces and compared with experiment and our earlier SWPS results. This work sets the stage for refinement of such potential surfaces via regression analysis of VRT spectroscopic data. {copyright} {ital 1999 American Institute of Physics.}

Using a spatially-distributed hydrologic biogeochemistry model to study the spatial variation of carbon processes in a Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Shi, Y.; Eissenstat, D. M.; Davis, K. J.; He, Y.

2016-12-01

Forest carbon processes are affected by, among other factors, soil moisture, soil temperature, soil nutrients and solar radiation. Most of the current biogeochemical models are 1-D and represent one point in space. Therefore, they cannot resolve the topographically driven hill-slope land surface heterogeneity or the spatial pattern of nutrient availability. A spatially distributed forest ecosystem model, Flux-PIHM-BGC, has been developed by coupling a 1-D mechanistic biogeochemical model Biome-BGC (BBGC) with a spatially distributed land surface hydrologic model, Flux-PIHM. Flux-PIHM is a coupled physically based model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model. Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as the land surface heterogeneities caused by topography. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1-D BBGC model, while soil nitrogen is transported among model grids via subsurface water flow. In each grid, Flux-PIHM provides BBGC with soil moisture, soil temperature, and solar radiation information, while BBGC provides Flux-PIHM with leaf area index. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna/Shale Hills critical zone observatory (SSHCZO). Model results suggest that the vegetation and soil carbon distribution is primarily constrained by nitorgen availability (affected by nitorgen transport via topographically driven subsurface flow), and also constrained by solar radiation and root zone soil moisture. The predicted vegetation and soil carbon distribution generally agrees with the macro pattern observed within the watershed. The coupled ecosystem-hydrologic model provides an important tool to study the impact of topography on watershed carbon processes, as well as the impact of climate change on water resources.

Modification of land-atmosphere interactions by CO2 effects: Implications for summer dryness and heat wave amplitude

NASA Astrophysics Data System (ADS)

Lemordant, Léo.; Gentine, Pierre; Stéfanon, Marc; Drobinski, Philippe; Fatichi, Simone

2016-10-01

Plant stomata couple the energy, water, and carbon cycles. We use the framework of Regional Climate Modeling to simulate the 2003 European heat wave and assess how higher levels of surface CO2 may affect such an extreme event through land-atmosphere interactions. Increased CO2 modifies the seasonality of the water cycle through stomatal regulation and increased leaf area. As a result, the water saved during the growing season through higher water use efficiency mitigates summer dryness and the heat wave impact. Land-atmosphere interactions and CO2 fertilization together synergistically contribute to increased summer transpiration. This, in turn, alters the surface energy budget and decreases sensible heat flux, mitigating air temperature rise. Accurate representation of the response to higher CO2 levels and of the coupling between the carbon and water cycles is therefore critical to forecasting seasonal climate, water cycle dynamics, and to enhance the accuracy of extreme event prediction under future climate.

Description and field analysis of a coupled ground-water/surface-water flow model (MODFLOW/BRANCH) with modifications for structures and wetlands in southern Dade County, Florida

USGS Publications Warehouse

Swain, E.D.; Howie, Barbara; Dixon, Joann

1996-01-01

A coupled surface-water model (BRANCH) and ground-water model (MODFLOW) model were tested to simulate the interacting wetlands/surface-water/ ground-water system of southern Dade County. Several options created for the MODFLOW ground- ground-water model were used in representing this field situation. The primary option is the MODBRANCH interfacing software, which allows leakage to be accounted for between the MODFLOW ground-water model and the BRANCH dynamic model for simulation of flow in an interconnected network of open channels. A modification to an existing software routine, which is referred to as BCF2, allows cells in MODFLOW to rewet when dry--a requirement in representing the seasonal wetlands in Dade County. A companion to BCF2 is the modified evapotranspiration routine EVT2. The EVT2 routine changes the cells where evapotranspiration occurs, depending on which cells are wet. The Streamlink package represents direct connections between the canals and wetlands at locations where canals open directly into overland flow. Within the BRANCH model, the capability to represent the numerous hydraulic structures, gated spillways, gated culverts, and pumps was added. The application of these modifications to model surface-water/ground-water interactions in southern Dade County demonstrated the usefulness of the coupled MODFLOW/BRANCH model. Ground-water and surface-water flows are both simulated with dynamic models. Flow exchange between models, intermittent wetting and drying, evapotranspiration, and hydraulic structure operations are all represented appropriately. Comparison was made with a simulation using the RIV1 package instead of MODBRANCH to represent the canals. RIV1 represents the canals by user-defined stages, and computes leakage to the aquifer. Greater accuracy in reproducing measured ground- water heads was achieved with MODBRANCH, which also computes dynamic flow conditions in the canals, unlike RIV1. The surface-water integrated flow and transport two-dimensional model (SWIFT2D) was also applied to the southeastern coastal wetlands for comparison with the wetlands flow approximation made in MODFLOW. MODFLOW simulates the wetlands as a highly conductive upper layer of the aquifer, whereas SWIFT2D solves the hydrodynamic equations. Comparison in this limited test demonstrated no specific advantage for either method of representation. However, much additional testing on a wider variety of geometric and hydraulic situations, such as in areas with greater tidal or other dynamic forcing effects, is needed to make definite conclusions. A submodel of the existing southern Dade County model schematization was used to examine water-delivery alternatives proposed by the U.S. Army Corps of Engineers. For this application, the coupled MODFLOW/BRANCH model was used as a design tool. A new canal and several pumps to be tested to maintain lower water levels in a residential area (while water levels in the Everglades are raised) were added to the model schematization. The pumps were assumed to have infinite supply capacity in the model so that their maximum pumping rates during the simulation could be used to determine pump sizes.

Full Coupling Between the Atmosphere, Surface, and Subsurface for Integrated Hydrologic Simulation

NASA Astrophysics Data System (ADS)

Davison, Jason Hamilton; Hwang, Hyoun-Tae; Sudicky, Edward A.; Mallia, Derek V.; Lin, John C.

2018-01-01

An ever increasing community of earth system modelers is incorporating new physical processes into numerical models. This trend is facilitated by advancements in computational resources, improvements in simulation skill, and the desire to build numerical simulators that represent the water cycle with greater fidelity. In this quest to develop a state-of-the-art water cycle model, we coupled HydroGeoSphere (HGS), a 3-D control-volume finite element surface and variably saturated subsurface flow model that includes evapotranspiration processes, to the Weather Research and Forecasting (WRF) Model, a 3-D finite difference nonhydrostatic mesoscale atmospheric model. The two-way coupled model, referred to as HGS-WRF, exchanges the actual evapotranspiration fluxes and soil saturations calculated by HGS to WRF; conversely, the potential evapotranspiration and precipitation fluxes from WRF are passed to HGS. The flexible HGS-WRF coupling method allows for unique meshes used by each model, while maintaining mass and energy conservation between the domains. Furthermore, the HGS-WRF coupling implements a subtime stepping algorithm to minimize computational expense. As a demonstration of HGS-WRF's capabilities, we applied it to the California Basin and found a strong connection between the depth to the groundwater table and the latent heat fluxes across the land surface.

A hybrid finite-difference and analytic element groundwater model

USGS Publications Warehouse

Haitjema, Henk M.; Feinstein, Daniel T.; Hunt, Randall J.; Gusyev, Maksym

2010-01-01

Regional finite-difference models tend to have large cell sizes, often on the order of 1–2 km on a side. Although the regional flow patterns in deeper formations may be adequately represented by such a model, the intricate surface water and groundwater interactions in the shallower layers are not. Several stream reaches and nearby wells may occur in a single cell, precluding any meaningful modeling of the surface water and groundwater interactions between the individual features. We propose to replace the upper MODFLOW layer or layers, in which the surface water and groundwater interactions occur, by an analytic element model (GFLOW) that does not employ a model grid; instead, it represents wells and surface waters directly by the use of point-sinks and line-sinks. For many practical cases it suffices to provide GFLOW with the vertical leakage rates calculated in the original coarse MODFLOW model in order to obtain a good representation of surface water and groundwater interactions. However, when the combined transmissivities in the deeper (MODFLOW) layers dominate, the accuracy of the GFLOW solution diminishes. For those cases, an iterative coupling procedure, whereby the leakages between the GFLOW and MODFLOW model are updated, appreciably improves the overall solution, albeit at considerable computational cost. The coupled GFLOW–MODFLOW model is applicable to relatively large areas, in many cases to the entire model domain, thus forming an attractive alternative to local grid refinement or inset models.

Nitrification in the euphotic zone as evidenced by nitrate dual isotopic composition: Observations from Monterey Bay, California

USGS Publications Warehouse

Wankel, Scott D.; Kendall, C.; Pennington, J.T.; Chavez, F.P.; Paytan, A.

2007-01-01

Coupled measurements of nitrate (NO3-), nitrogen (N), and oxygen (O) isotopic composition (??15NNO3 and ??18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous and variable influence of both phytoplankton NO3- assimilation and nitrification within the euphotic zone. Specifically, increases ??18ONO3 were consistently greater than those in ??15NN03. A coupled isotope steady state box model was used to estimate the amount of NO3- supplied by nitrification in surface waters relative to that supplied from deeper water. The model highlights the importance of the branching reaction during ammonium (NH4+) consumption, in which NH4+ either serves as a substrate for regenerated production or for nitrification. Our observations indicate that a previously unrecognized proportion of nitrate-based productivity, on average 15 to 27%, is supported by nitrification in surface waters and should not be considered new production. This work also highlights the need for a better understanding of isotope effects of NH4+ oxidation, NH4+ assimilation, and NO4+ assimilation in marine environments.

The (impossible?) formation of acetaldehyde on the grain surfaces: insights from quantum chemical calculations

NASA Astrophysics Data System (ADS)

Enrique-Romero, J.; Rimola, A.; Ceccarelli, C.; Balucani, N.

2016-06-01

Complex Organic Molecules (COMs) have been detected in the interstellar medium (ISM). However, it is not clear whether their synthesis occurs on the icy surfaces of interstellar grains or via a series of gas-phase reactions. As a test case of the COMs synthesis in the ISM, we present new quantum chemical calculations on the formation of acetaldehyde (CH3CHO) from the coupling of the HCO and CH3 radicals, both in gas phase and on water ice surfaces. The binding energies of HCO and CH3 on the amorphous water ice were also computed (2333 and 734 K, respectively). Results indicate that, in gas phase, the products could be either CH3CHO, CH4 + CO, or CH3OCH, depending on the relative orientation of the two radicals. However, on the amorphous water ice, only the CH4 + CO product is possible due to the geometrical constraints imposed by the water ice surface. Therefore, acetaldehyde cannot be synthesized by the CH3 + HCO coupling on the icy grains. We discuss the implications of these results and other cases, such as ethylene glycol and dimethyl ether, in which similar situations can occur, suggesting that formation of these molecules on the grain surfaces might be unlikely.

Effects of Precipitation on Ocean Mixed-Layer Temperature and Salinity as Simulated in a 2-D Coupled Ocean-Cloud Resolving Atmosphere Model

NASA Technical Reports Server (NTRS)

Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.

1999-01-01

A two-dimensional coupled ocean-cloud resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets. The model couples a cloud resolving model with an embedded mixed layer-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-layer temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-layer temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-layer salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed layers and weak cooling rates so that the nocturnal mixed-layer temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed layers over convective areas while the nocturnal heat loss causes deep mixed layer over convection-free areas so that the mixed-layer temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures.

LIS-HYMAP coupled Hydrological Modeling in the Nile River Basin and the Greater Horn of Africa

NASA Astrophysics Data System (ADS)

Jung, H. C.; Getirana, A.; Policelli, F. S.

2015-12-01

Water scarcity and resources in Africa have been exacerbated by periodic droughts and floods. However, few studies show the quantitative analysis of water balance or basin-scale hydrological modeling in Northeast Africa. The NASA Land Information System (LIS) is implemented to simulate land surface processes in the Nile River Basin and the Greater Horn of Africa. In this context, the Noah land surface model (LSM) and the Hydrological Modeling and Analysis Platform (HYMAP) are used to reproduce the water budget and surface water (rivers and floodplains) dynamics in that region. The Global Data Assimilation System (GDAS) meteorological dataset is used to force the system . Due to the unavailability of recent ground-based observations, satellite data are considered to evaluate first model outputs. Water levels at 10 Envisat virtual stations and water discharges at a gauging station are used to provide model performance coefficients (e.g. Nash-Sutcliffe, delay index, relative error). We also compare the spatial and temporal variations of flooded areas from the model with the Global Inundation Extent from Multi-Satellites (GIEMS) and the Alaska Satellite Facility (ASF)'s MEaSUREs Wetland data. Finally, we estimate surface water storage variations using a hypsographic curve approach with Shuttle Radar Topography Mission (SRTM) topographic data and evaluate the model-derived water storage changes in both river and floodplain. This study demonstrates the feasibility of using LIS-HYMAP coupled modeling to support seasonal forecast methods for prediction of decision-relevant metrics of hydrologic extremes.

Oceanic response to tropical cyclone `Phailin' in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Pant, V.; Prakash, K. R.

2016-02-01

Vertical mixing largely explains surface cooling induced by Tropical Cyclones (TCs). However, TC-induced upwelling of deeper waters plays an important role as it partly balances the warming of subsurface waters induced by vertical mixing. Below 100 m, vertical advection results in cooling that persists for a few days after the storm. The present study investigates the integrated ocean response to tropical cyclone `Phaillin' (10-14 October 2013) in the Bay of Bengal (BoB) through both coupled and stand-alone ocean-atmosphere models. Two numerical experiments with different coupling configurations between Regional Ocean Modelling System (ROMS) and Weather Research and Forecasting (WRF) were performed to investigate the impact of Phailin cyclone on the surface and sub-surface oceanic parameters. In the first experiment, ocean circulation model ROMS observe surface wind forcing from a mesoscale atmospheric model (WRF with nested damin setup), while rest forcing parameters are supplied to ROMS from NCEP data. In the second experiment, all surface forcing data to ROMS directly comes from WRF. The modeling components and data fields exchanged between atmospheric and oceanic models are described. The coupled modeling system is used to identify model sensitivity by exchanging prognostic variable fields between the two model components during simulation of Phallin cyclone (10-14 October 2013) in the BoB.In general, the simulated Phailin cyclone track and intensities agree well with observations in WRF simulations. Further, the inter-comparison between stand-alone and coupled model simulations validated against observations highlights better performance of coupled modeling system in simulating the oceanic conditions during the Phailin cyclone event.

Variations in the amount of water ice on Ceres' surface suggest a seasonal water cycle.

PubMed

Raponi, Andrea; De Sanctis, Maria Cristina; Frigeri, Alessandro; Ammannito, Eleonora; Ciarniello, Mauro; Formisano, Michelangelo; Combe, Jean-Philippe; Magni, Gianfranco; Tosi, Federico; Carrozzo, Filippo Giacomo; Fonte, Sergio; Giardino, Marco; Joy, Steven P; Polanskey, Carol A; Rayman, Marc D; Capaccioni, Fabrizio; Capria, Maria Teresa; Longobardo, Andrea; Palomba, Ernesto; Zambon, Francesca; Raymond, Carol A; Russell, Christopher T

2018-03-01

The dwarf planet Ceres is known to host a considerable amount of water in its interior, and areas of water ice were detected by the Dawn spacecraft on its surface. Moreover, sporadic water and hydroxyl emissions have been observed from space telescopes. We report the detection of water ice in a mid-latitude crater and its unexpected variation with time. The Dawn spectrometer data show a change of water ice signatures over a period of 6 months, which is well modeled as ~2-km 2 increase of water ice. The observed increase, coupled with Ceres' orbital parameters, points to an ongoing process that seems correlated with solar flux. The reported variation on Ceres' surface indicates that this body is chemically and physically active at the present time.

Anticipated Improvements to Net Surface Freshwater Fluxes from GPM

NASA Technical Reports Server (NTRS)

Smith, Eric A.

2005-01-01

Evaporation and precipitation over the oceans play very important roles in the global water cycle, upper-ocean heat budget, ocean dynamics, and coupled ocean-atmosphere dynamics. In the conventional representation of the terrestrial water cycle, the assumed role of the oceans is to act as near-infinite reservoirs of water with the main drivers of the water cycle being land- atmosphere interactions in which excess precipitation (P) over evaporation (E) is returned to the oceans as surface runoff and baseflow. Whereas this perspective is valid for short space and time scales -- fundamental principles, available observed estimates, and results from models indicate that the oceans play a far more important role in the large-scale water cycle at seasonal and longer timescales. Approximately 70-80% of the total global evaporation and precipitation occurs over oceans. Moreover, latent heat release into the atmosphere over the oceans is the major heat source driving global atmospheric circulations, with the moisture transported by circulations from oceans to continents being the major source of water precipitating over land. Notably, the major impediment in understanding and modeling the oceans role in the global water cycle is the lack of reliable net surface freshwater flux estimates (E - P fluxes) at the salient spatial and temporal resolutions, i.e., consistent coupled weekly to monthly E - P gridded datasets.

Ground Source Heat Pumps vs. Conventional HVAC: A Comparison of Economic and Environmental Costs

DTIC Science & Technology

2009-03-26

of systems are surface water heat pumps (SWHPs), ground water heat pumps (GWHPs), and ground coupled heat pumps ( GCHPs ) (Kavanaugh & Rafferty, 1997...Kavanaugh & Rafferty, 1997). Ground Coupled Heat Pumps (Closed-Loop Ground Source Heat Pumps) GCHPs , otherwise known as closed-loop GSHPs, are the...Significant confusion has arisen through the use of GCHP and closed-loop GSHP terminology. Closed-loop GSHP is the preferred nomenclature for this

Coniferyl alcohol reactivity at the air/water interface.

PubMed

Cathala, Bernard; Aguié-Béghin, Véronique; Douillard, Roger

2004-01-01

In order to investigate the sensitivity of the lignin monomer coupling reactions to the environment physicochemical conditions, coniferyl alcohol (CA) was polymerised at the air/water interface. Characterisation of the interface during the reaction by surface pressure measurement and ellipsometry demonstrates that the reaction occurs near or at the interface. Coupling products were analysed by HPLC and compared to reaction products obtained in the case of polymerisation in solution. Relative proportions of beta-beta and beta-O-4 dehydrodimers were found to increase in air/water interface experiment.

Improved global simulation of groundwater-ecosystem interactions via tight coupling of a dynamic global ecosystem model and a global hydrological model

NASA Astrophysics Data System (ADS)

Braakhekke, Maarten; Rebel, Karin; Dekker, Stefan; Smith, Benjamin; Sutanudjaja, Edwin; van Beek, Rens; van Kampenhout, Leo; Wassen, Martin

2017-04-01

In up to 30% of the global land surface ecosystems are potentially influenced by the presence of a shallow groundwater table. In these regions upward water flux by capillary rise increases soil moisture availability in the root zone, which has a strong effect on evapotranspiration, vegetation dynamics, and fluxes of carbon and nitrogen. Most global hydrological models and several land surface models simulate groundwater table dynamics and their effects on land surface processes. However, these models typically have relatively simplistic representation of vegetation and do not consider changes in vegetation type and structure. Dynamic global vegetation models (DGVMs), describe land surface from an ecological perspective, combining detailed description of vegetation dynamics and structure, and biogeochemical processes and are thus more appropriate to simulate the ecological and biogeochemical effects of groundwater interactions. However, currently virtually all DGVMs ignore these effects, assuming that water tables are too deep to affect soil moisture in the root zone. We have implemented a tight coupling between the dynamic global ecosystem model LPJ-GUESS and the global hydrological model PCR-GLOBWB, which explicitly simulates groundwater dynamics. This coupled model allows us to explicitly account for groundwater effects on terrestrial ecosystem processes at global scale. Results of global simulations indicate that groundwater strongly influences fluxes of water, carbon and nitrogen, in many regions, adding up to a considerable effect at the global scale.

Non-isothermal processes during the drying of bare soil: Model Development and Validation

NASA Astrophysics Data System (ADS)

Sleep, B.; Talebi, A.; O'Carrol, D. M.

2017-12-01

Several coupled liquid water, water vapor, and heat transfer models have been developed either to study non-isothermal processes in the subsurface immediately below the ground surface, or to predict the evaporative flux from the ground surface. Equilibrium phase change between water and gas phases is typically assumed in these models. Recently, a few studies have questioned this assumption and proposed a coupled model considering kinetic phase change. However, none of these models were validated against real field data. In this study, a non-isothermal coupled model incorporating kinetic phase change was developed and examined against the measured data from a green roof test module. The model also incorporated a new surface boundary condition for water vapor transport at the ground surface. The measured field data included soil moisture content and temperature at different depths up to the depth of 15 cm below the ground surface. Lysimeter data were collected to determine the evaporation rates. Short and long wave radiation, wind velocity, air ambient temperature and relative humidity were measured and used as model input. Field data were collected for a period of three months during the warm seasons in south eastern Canada. The model was calibrated using one drying period and then several other drying periods were simulated. In general, the model underestimated the evaporation rates in the early stage of the drying period, however, the cumulative evaporation was in good agreement with the field data. The model predicted the trends in temperature and moisture content at the different depths in the green roof module. The simulated temperature was lower than the measured temperature for most of the simulation time with the maximum difference of 5 ° C. The simulated moisture content changes had the same temporal trend as the lysimeter data for the events simulated.

Surface-active ionic liquids for palladium-catalysed cross coupling in water: effect of ionic liquid concentration on the catalytically active species† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7ra07757b

PubMed Central

Taskin, Meltem; Cognigni, Alice; Zirbs, Ronald; Reimhult, Erik

2017-01-01

We report the design and synthesis of surface-active ionic liquids for application in palladium-catalyzed cross coupling reactions. A series of dodecylimidazolium-based ionic liquids were applied as additives in the Heck reaction of ethyl acrylate and iodobenzene, and high yields of >90% could be obtained in water without the addition of further ligands. Our results indicate that the ionic liquid concentration in water is the key factor affecting the formation of the catalytically active species and hence the yield. Moreover, imidazolium-based ionic liquids that are able to form a carbene species differ significantly from conventional cationic surfactants, as a concentration dependent formation of the N-heterocyclic carbene complex was observed. PMID:29308189

Numerical analysis of heat and mass transfer for water recovery in an evaporative cooling tower

NASA Astrophysics Data System (ADS)

Lee, Hyunsub; Son, Gihun

2017-11-01

Numerical analysis is performed for water recovery in an evaporative cooling tower using a condensing heat exchanger, which consists of a humid air channel and an ambient dry air channel. The humid air including water vapor produced in an evaporative cooling tower is cooled by the ambient dry air so that the water vapor is condensed and recovered to the liquid water. The conservation equations of mass, momentum, energy and vapor concentration in each fluid region and the energy equation in a solid region are simultaneously solved with the heat and mass transfer boundary conditions coupled to the effect of condensation on the channel surface of humid air. The present computation demonstrates the condensed water film distribution on the humid air channel, which is caused by the vapor mass transfer between the humid air and the colder water film surface, which is coupled to the indirect heat exchange with the ambient air. Computations are carried out to predict water recovery rate in parallel, counter and cross-flow type heat exchangers. The effects of air flow rate and channel interval on the water recovery rate are quantified.

Quantifying the Contribution of Regional Aquifers to Stream Flow in the Upper Colorado River Basin

NASA Astrophysics Data System (ADS)

Masbruch, M.; Dickinson, J.

2017-12-01

The growing population of the arid and semiarid southwestern U.S. relies on over-allocated surface water resources and poorly quantified groundwater resources. In the Upper Colorado River Basin, recent studies have found that about 50 percent of the surface water at U.S. Geological Survey (USGS) stream gages is derived from groundwater contributions as base flow. Prior USGS and other studies for the Colorado Plateau region have mainly examined groundwater and surface water as separate systems, and there has yet to be regional synthesis of groundwater availability in aquifers that contribute to surface water. A more physically based representation of groundwater flow could improve simulations of surface-water capture by groundwater pumping, and changes of groundwater discharge to surface water caused by possible shifts in the distribution, magnitude, and timing of recharge in the future. We seek to improve conceptual and numerical models of groundwater and surface-water interactions in the Colorado Plateau region as part of a USGS regional groundwater availability assessment. Numerical modeling is used to simulate and quantify the base flow from groundwater to the Colorado River and its major tributaries. Groundwater/surface-water interactions will be simulated using the USGS code GSFLOW, which couples the Precipitation Runoff Modeling System (PRMS) to the groundwater flow model MODFLOW. Initial results suggest that interactions between groundwater and surface water are important for projecting long-term changes in surface water budgets.

A numerical study of wave-current interaction through surface and bottom stresses: Coastal ocean response to Hurricane Fran of 1996

NASA Astrophysics Data System (ADS)

Xie, L.; Pietrafesa, L. J.; Wu, K.

2003-02-01

A three-dimensional wave-current coupled modeling system is used to examine the influence of waves on coastal currents and sea level. This coupled modeling system consists of the wave model-WAM (Cycle 4) and the Princeton Ocean Model (POM). The results from this study show that it is important to incorporate surface wave effects into coastal storm surge and circulation models. Specifically, we find that (1) storm surge models without coupled surface waves generally under estimate not only the peak surge but also the coastal water level drop which can also cause substantial impact on the coastal environment, (2) introducing wave-induced surface stress effect into storm surge models can significantly improve storm surge prediction, (3) incorporating wave-induced bottom stress into the coupled wave-current model further improves storm surge prediction, and (4) calibration of the wave module according to minimum error in significant wave height does not necessarily result in an optimum wave module in a wave-current coupled system for current and storm surge prediction.

Interannual variability (1979-2013) of the North-Western Mediterranean deep water mass formation: past observation reanalysis and coupled ocean-atmosphere high-resolution modelling

NASA Astrophysics Data System (ADS)

Somot, Samuel; Houpert, Loic; Sevault, Florence; Testor, Pierre; Bosse, Anthony; Durrieu de Madron, Xavier; Dubois, Clotilde; Herrmann, Marine; Waldman, Robin; Bouin, Marie-Noëlle; Cassou, Christophe

2015-04-01

The North-Western Mediterranean Sea is known as one of the only place in the world where open-sea deep convection occurs (often up to more than 2000m) with the formation of the Western Mediterranean Deep Water (WMDW). This phenomena is mostly driven by local preconditioning of the water column and strong buoyancy losses during Winter. At the event scale, the WMDW formation is characterized by different phases (preconditioning, strong mixing, restratification and spreading), intense air-sea interaction and strong meso-scale activity but, on a longer time scale, it also shows a large interannual variability and may be strongly affected by climate change with impact on the regional biogeochemistry. Therefore observing, simulating and understanding the long-term temporal variability of the North-Western Mediterranean deep water formation is still today a very challenging task. We try here to tackle those issues thanks to (1) a thorough reanalysis of past in-situ observations (CTD, Argo, surface and deep moorings, gliders) and (2) an ERA-Interim driven simulation using a recently-developed fully coupled Regional Climate System Model (CNRM-RCSM4, Sevault et al. 2014). The multi-decadal simulation (1979-2013) is designed to be temporally and spatially homogeneous with a realistic chronology, a high resolution representation of both the regional ocean and atmosphere, specific initial conditions, a long-term spin-up and a full ocean-atmosphere coupling without constraint at the air-sea interface. The observation reanalysis allows to reconstruct interannual time series of deep water formation indicators (ocean surface variables, mixed layer depth, surface of the convective area, dense water volumes and characteristics of the deep water). Using the observation-based indicators and the model outputs, the 34 Winters of the period 1979-2013 are analysed in terms of weather regimes, related Winter air-sea fluxes, ocean preconditioning, mixed layer depth, surface of the convective area, deep water formation rate and long-term evolution of the deep water hydrology.

Optimizing the well pumping rate and its distance from a stream

NASA Astrophysics Data System (ADS)

Abdel-Hafez, M. H.; Ogden, F. L.

2008-12-01

Both ground water and surface water are very important component of the water resources. Since they are coupled systems in riparian areas, management strategies that neglect interactions between them penalize senior surface water rights to the benefit of junior ground water rights holders in the prior appropriation rights system. Water rights managers face a problem in deciding which wells need to be shut down and when, in the case of depleted stream flow. A simulation model representing a combined hypothetical aquifer and stream has been developed using MODFLOW 2000 to capture parameter sensitivity, test management strategies and guide field data collection campaigns to support modeling. An optimization approach has been applied to optimize both the well distance from the stream and the maximum pumping rate that does not affect the stream discharge downstream the pumping wells. Conjunctive management can be modeled by coupling the numerical simulation model with the optimization techniques using the response matrix technique. The response matrix can be obtained by calculating the response coefficient for each well and stream. The main assumption of the response matrix technique is that the amount of water out of the stream to the aquifer is linearly proportional to the well pumping rate (Barlow et al. 2003). The results are presented in dimensionless form, which can be used by the water managers to solve conflicts between surface water and ground water holders by making the appropriate decision to choose which well need to be shut down first.

Contrasting cloud composition between coupled and decoupled marine boundary layer clouds

NASA Astrophysics Data System (ADS)

Wang, Zhen; Mora Ramirez, Marco; Dadashazar, Hossein; MacDonald, Alex B.; Crosbie, Ewan; Bates, Kelvin H.; Coggon, Matthew M.; Craven, Jill S.; Lynch, Peng; Campbell, James R.; Azadi Aghdam, Mojtaba; Woods, Roy K.; Jonsson, Haflidi; Flagan, Richard C.; Seinfeld, John H.; Sorooshian, Armin

2016-10-01

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds for dissolved nonwater substances. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (Eastern Pacific Emitted Aerosol Cloud Experiment 2011, Nucleation in California Experiment 2013, and Biological and Oceanic Atmospheric Study 2015). Decoupled clouds exhibited significantly lower air-equivalent mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and subcloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Nonrefractory submicrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Sodium and chloride dominated in terms of air-equivalent concentration in cloud water for coupled clouds, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea-salt constituents (e.g., Cl, Na, Mg, and K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. Satellite and Navy Aerosol Analysis and Prediction System-based reanalysis data are compared with each other, and the airborne data to conclude that limitations in resolving boundary layer processes in a global model prevent it from accurately quantifying observed differences between coupled and decoupled cloud composition.

Modification of land-atmosphere interactions by CO2 effects

NASA Astrophysics Data System (ADS)

Lemordant, Leo; Gentine, Pierre

2017-04-01

Plant stomata couple the energy, water and carbon cycles. Increased CO2 modifies the seasonality of the water cycle through stomatal regulation and increased leaf area. As a result, the water saved during the growing season through higher water use efficiency mitigates summer dryness and the impact of potential heat waves. Land-atmosphere interactions and CO2 fertilization together synergistically contribute to increased summer transpiration. This, in turn, alters the surface energy budget and decreases sensible heat flux, mitigating air temperature rise. Accurate representation of the response to higher CO2 levels, and of the coupling between the carbon and water cycles are therefore critical to forecasting seasonal climate, water cycle dynamics and to enhance the accuracy of extreme event prediction under future climate.

A numerical study on the effects of wave-current-surge interactions on the height and propagation of sea surface waves in Charleston Harbor during Hurricane Hugo 1989

NASA Astrophysics Data System (ADS)

Liu, Huiqing; Xie, Lian

2009-06-01

The effects of wave-current interactions on ocean surface waves induced by Hurricane Hugo in and around the Charleston Harbor and its adjacent coastal waters are examined by using a three-dimensional (3D) wave-current coupled modeling system. The 3D storm surge modeling component of the coupled system is based on the Princeton Ocean Model (POM), the wave modeling component is based on the third generation wave model, Simulating WAves Nearshore (SWAN), and the inundation model is adopted from [Xie, L., Pietrafesa, L. J., Peng, M., 2004. Incorporation of a mass-conserving inundation scheme into a three-dimensional storm surge model. J. Coastal Res., 20, 1209-1223]. The results indicate that the change of water level associated with the storm surge is the primary cause for wave height changes due to wave-surge interaction. Meanwhile, waves propagating on top of surge cause a feedback effect on the surge height by modulating the surface wind stress and bottom stress. This effect is significant in shallow coastal waters, but relatively small in offshore deep waters. The influence of wave-current interaction on wave propagation is relatively insignificant, since waves generally propagate in the direction of the surface currents driven by winds. Wave-current interactions also affect the surface waves as a result of inundation and drying induced by the storm. Waves break as waters retreat in regions of drying, whereas waves are generated in flooded regions where no waves would have occurred without the flood water.

Coupling online effects-based monitoring with physicochemical, optical, and spectroscopy methods to assess quality at a surface water intake

EPA Science Inventory

Effects-based monitoring of water quality is a proven approach to monitoring the status of a water source. Only biological material can integrate factors which dictate toxicity. Online Toxicity Monitors (OTMs) provide a means to digitize sentinel organism responses to dynamic wa...

Groundwater and surface water exchange and resulting Nitrate dynamics in the Bogue Phalia Basin in northwestern Mississippi

USGS Publications Warehouse

Barlow, Jeannie R.; Coupe, Richard H.

2012-01-01

During April 2007 through September 2008, the USGS collected hydrogeologic and water-quality data from a site on the Bogue Phalia to evaluate the role of groundwater and surface-water interaction on the transport of nitrate to the shallow sand and gravel aquifer underlying the Mississippi Alluvial Plain in northwestern Mississippi. A two-dimensional groundwater/surface-water exchange model was developed using temperature and head data and VS2DH, a variably saturated flow and energy transport model. Results from this model showed that groundwater/surface-water exchange at the site occurred regularly and recharge was laterally extensive into the alluvial aquifer. Nitrate was consistently reported in surface-water samples (n = 52, median concentration = 39.8 μmol/L) although never detected in samples collected from in-stream piezometers or shallow monitoring wells adjacent to the stream (n = 46). These two facts, consistent detections of nitrate in surface water and no detections of nitrate in groundwater, coupled with model results that indicate large amounts of surface water moving through an anoxic streambed, support the case for denitrification and nitrate loss through the streambed.

Reductive dechlorination of trichloroethylene by iron bimetallics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orth, R.G.; Dauda, T.; McKenzie, D.E.

1998-07-01

Reductive dechlorination using a zero valence metal such as iron has seen an increase in interest with the extension of iron dechlorination to in-situ treatment of ground water. Studies to increase the rate of dechlorination and the long term stability have lead many to examine the use of bimetallic iron systems. Results are shown for bimetallic iron systems of Cu, Sn, Ni, Ag, Au, and Pd. All of these bimetallic couples form a galvanic couple which increase corrosion rates and the production of hydrogen. Increased rates of reaction normalized to surface area were observed for all the couples. The reactionmore » rates were found to depended on surface area and surface coverage of the iron. The results of studies in deuterium oxide indicate that the pathways changed as the bimetallic is changed and that the pathway in all cases could be a combination of dehydrohalgenation and sequential dechlorination. Degradation of DNAPL TCE by iron was found to be zero order and the type of product observed was different from that observed for TCE dissolved in water.« less

Simultaneous measurement of displacement current and absorption spectra of Langmuir film

NASA Astrophysics Data System (ADS)

Xu, Xiaobin; Kubota, Tohru; Iwamoto, Mitsumasa

1995-07-01

A Maxwell-displacement-current measuring system coupled with the system used for the measurement of absorption spectra of monolayers on a water surface has been developed. Using this system, the displacement current and the absorbance across monolayers of squarylium dye at the air/water surface were detected. It was found that the change in J aggregate in the monolayers with monolayer compression was detectable using the system.

Hydrogen bonding at the water surface revealed by isotopic dilution spectroscopy.

PubMed

Stiopkin, Igor V; Weeraman, Champika; Pieniazek, Piotr A; Shalhout, Fadel Y; Skinner, James L; Benderskii, Alexander V

2011-06-08

The air-water interface is perhaps the most common liquid interface. It covers more than 70 per cent of the Earth's surface and strongly affects atmospheric, aerosol and environmental chemistry. The air-water interface has also attracted much interest as a model system that allows rigorous tests of theory, with one fundamental question being just how thin it is. Theoretical studies have suggested a surprisingly short 'healing length' of about 3 ångströms (1 Å = 0.1 nm), with the bulk-phase properties of water recovered within the top few monolayers. However, direct experimental evidence has been elusive owing to the difficulty of depth-profiling the liquid surface on the ångström scale. Most physical, chemical and biological properties of water, such as viscosity, solvation, wetting and the hydrophobic effect, are determined by its hydrogen-bond network. This can be probed by observing the lineshape of the OH-stretch mode, the frequency shift of which is related to the hydrogen-bond strength. Here we report a combined experimental and theoretical study of the air-water interface using surface-selective heterodyne-detected vibrational sum frequency spectroscopy to focus on the 'free OD' transition found only in the topmost water layer. By using deuterated water and isotopic dilution to reveal the vibrational coupling mechanism, we find that the free OD stretch is affected only by intramolecular coupling to the stretching of the other OD group on the same molecule. The other OD stretch frequency indicates the strength of one of the first hydrogen bonds encountered at the surface; this is the donor hydrogen bond of the water molecule straddling the interface, which we find to be only slightly weaker than bulk-phase water hydrogen bonds. We infer from this observation a remarkably fast onset of bulk-phase behaviour on crossing from the air into the water phase.

Water-walled microfluidics for high-optical finesse cavities

NASA Astrophysics Data System (ADS)

Maayani, Shai; Martin, Leopoldo L.; Carmon, Tal

2016-01-01

In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 re-circulations of light. The droplets survive for >16 h using a technique that is based on a nano-water bridge from the droplet to a distant reservoir to compensate for evaporation. More than enabling a nearly-perfect optical overlap with water, atomic-level surface smoothness that minimizes scattering loss, and ~99% coupling efficiency from a standard fibre. Surface tension in our droplet is 8,000 times stronger than gravity, suggesting a new class of devices with water-made walls, for new fields of study including opto-capillaries.

Regional Mapping of Coupled Fluxes of Carbon and Water Using Multi-Sensor Fusion Techniques

NASA Astrophysics Data System (ADS)

Schull, M. A.; Anderson, M. C.; Semmens, K. A.; Yang, Y.; Gao, F.; Hain, C.; Houborg, R.

2014-12-01

In an ever-changing climate there is an increasing need to measure the fluxes of water, energy and carbon for decision makers to implement policies that will help mitigate the effects of climate change. In an effort to improve drought monitoring, water resource management and agriculture assessment capabilities, a multi-scale and multi-sensor framework for routine mapping of land-surface fluxes of water and energy at field to regional scales has been established. The framework uses the ALEXI (Atmosphere Land Exchange Inverse)/DisALEXI (Disaggregated ALEXI) suite of land-surface models forced by remotely sensed data from Landsat, MODIS (MODerate resolution Imaging Spectroradiometer), and GOES (Geostationary Operational Environmental Satellite). Land-surface temperature (LST) can be an effective substitute for in-situ surface moisture observations and a valuable metric for constraining land-surface fluxes at sub-field scales. The adopted multi-scale thermal-based land surface modeling framework facilitates regional to local downscaling of water and energy fluxes by using a combination of shortwave reflective and thermal infrared (TIR) imagery from GOES (4-10 km; hourly), MODIS (1 km; daily), and Landsat (30-100 m; bi-weekly). In this research the ALEXI/DisALEXI modeling suite is modified to incorporate carbon fluxes using a stomatal resistance module, which replaces the Priestley-Taylor latent heat approximation. In the module, canopy level nominal light-use-efficiency (βn) is the parameter that modulates the flux of water and carbon in and out of the canopy. Leaf chlorophyll (Chl) is a key parameter for quantifying variability in photosynthetic efficiency to facilitate the spatial distribution of coupled carbon and water retrievals. Spatial distribution of Chl are retrieved from Landsat (30 m) using a surface reflectance dataset as input to the REGularized canopy reFLECtance (REGFLEC) tool. The modified ALEXI/DisALEXI suite is applied to regions of rain fed and irrigated soybean and maize agricultural landscapes within the continental U.S. and flux estimates are compared with flux tower observations.

Improving the Amazonian Hydrologic Cycle in a Coupled Land-Atmosphere, Single Column Model

NASA Astrophysics Data System (ADS)

Harper, A. B.; Denning, S.; Baker, I.; Prihodko, L.; Branson, M.

2006-12-01

We have coupled a land-surface model, the Simple Biosphere Model (SiB3), to a single column of the Colorado State University General Circulation Model (CSU-GCM) in the Amazon River Basin. This is a preliminary step in the broader goal of improved simulation of Basin-wide hydrology. A previous version of the coupled model (SiB2) showed drought and catastrophic dieback of the Amazon rain forest. SiB3 includes updated soil hydrology and root physiology. Our test area for the coupled single column model is near Santarem, Brazil, where measurements from the km 83 flux tower in the Tapajos National Forest can be used to evaluate model output. The model was run for 2001 using NCEP2 Reanalysis as driver data. Preliminary results show that the updated biosphere model coupled to the GCM produces improved simulations of the seasonal cycle of surface water balance and precipitation. Comparisons of the diurnal and seasonal cycles of surface fluxes are also being made.

Controlled Interphases in Glass Fiber and Particulate Reinforced Polymers: Structure of Silane Coupling Agents in Solutions and On Substrates

DTIC Science & Technology

1993-01-01

to dissolve into water. Table 3. Typical industrially used silane coupling agents Organofunctional Chemical Formula Group Cationic styryl CH2...can also react with the surface as some unreacted silanol groups remain in the oligomers. The notion of physisorbed and chemisorbed silanes is used ...silanes use many silanol groups for covalent bonding with the substrate surface whereas the loosely chemisorbed silanes use only a few silanols to bond to

Determination of total arsenic and arsenic species in drinking water, surface water, wastewater, and snow from Wielkopolska, Kujawy-Pomerania, and Lower Silesia provinces, Poland.

PubMed

Komorowicz, Izabela; Barałkiewicz, Danuta

2016-09-01

Arsenic is a ubiquitous element which may be found in surface water, groundwater, and drinking water. In higher concentrations, this element is considered genotoxic and carcinogenic; thus, its level must be strictly controlled. We investigated the concentration of total arsenic and arsenic species: As(III), As(V), MMA, DMA, and AsB in drinking water, surface water, wastewater, and snow collected from the provinces of Wielkopolska, Kujawy-Pomerania, and Lower Silesia (Poland). The total arsenic was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and arsenic species were analyzed with use of high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC/ICP-MS). Obtained results revealed that maximum total arsenic concentration determined in drinking water samples was equal to 1.01 μg L(-1). The highest concentration of total arsenic in surface water, equal to 3778 μg L(-1) was determined in Trująca Stream situated in the area affected by geogenic arsenic contamination. Total arsenic concentration in wastewater samples was comparable to those determined in drinking water samples. However, significantly higher arsenic concentration, equal to 83.1 ± 5.9 μg L(-1), was found in a snow sample collected in Legnica. As(V) was present in all of the investigated samples, and in most of them, it was the sole species observed. However, in snow sample collected in Legnica, more than 97 % of the determined concentration, amounting to 81 ± 11 μg L(-1), was in the form of As(III), the most toxic arsenic species.

In Vivo Determination of the Complex Elastic Moduli of Cetacean Head Tissue

DTIC Science & Technology

2009-03-01

digitization of the modulated carrier signaT. Pure-tone ultrasonic vibrometry has been implemented in both air - coupled and water- coupled systems for...and J. Sabatier, " Air - coupled ultrasonic sensing of grass-covered vibrating surfaces; qualitative comparisons with laser vibrometry ", J. Acoust. Soc...follow-on grant. 2.2 Range discrimination in continuous-wave ultrasonic vibrometry The following Is adapted from a manuscript in preparation for

Identifying the hotspots of non-renewable water use using HiGW-MAT: A new land surface model coupled with human interventions and ground water reservoir

NASA Astrophysics Data System (ADS)

Oki, T.; Pokhrel, Y. N.; Yeh, P. J.; Koirala, S.; Kanae, S.; Hanasaki, N.

2011-12-01

The real hydrological cycles on the Earth are not natural anymore. Global hydrological model simulations of the water cycle and available water resources should have an ability to consider the effects of human interventions on hydrological cycles. Anthropogenic activity modules (Hanasaki et al., 2008), such as reservoir operation, crop growth and water demand in crop lands, and environmental flows, were incorporated into a land surface model called MATSIRO (Takata et al., 2003), to form a new model, MAT-HI (Pokhrel et al., 2011). Total terrestrial water storages (TWS) in large river basins were estimated using the new model by off-line simulation, and compared with the TWS observed by GRACE for 2002-2007. The results showed MAT-HI has an advantage estimating TWS particularly in arid river basins compared with H08 (Hanasaki et al., 2008). MAT-HI was further coupled with a module representing the ground water level fluctuations (Yeh et al., 2005), and consists a new land surface scheme HiGW-MAT (Human Intervention and Ground Water coupled MATSIRO). HiGW-MAT is also associated with a scheme tracing the origin and flow path with the consideration on the sources of water withdrawal from stream flow, medium-size reservoirs and nonrenewable groundwater in addition to precipitation to croplands enabled the assessment of the origin of water producing major crops as Hanasaki et al. (2010). Areas highly dependent on nonrenewable groundwater are detected in the Pakistan, Bangladesh, western part of India, north and western parts of China, some regions in the Arabian Peninsula and the western part of the United States through Mexico. Cumulative nonrenewable groundwater withdrawals estimated by the model are corresponding fairly well with the country statistics of total groundwater withdrawals. Ground water table depletions in large aquifers in US estimated by HiGW-MAT were compared with in-situ observational data, and the correspondences are very good. Mean global exploitation of ground water for 2000 estimated by HiGW-MAT is 450 km3/y as an excess of ground water withdrawal over natural recharge into aquifer.

Response of water temperature to surface wave effects in the Baltic Sea: simulations with the coupled NEMO-WAM model

NASA Astrophysics Data System (ADS)

Alari, Victor; Staneva, Joanna; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian; Janssen, Peter

2016-04-01

The effects of wind waves on the Baltic Sea water temperature has been studied by coupling the hydrodynamical model NEMO with the wave model WAM. The wave forcing terms that have been taken into consideration are: Stokes-Coriolis force, seastate dependent energy flux and sea-state dependent momentum flux. The combined role of these processes as well as their individual contributions on simulated temperature is analysed. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwellinǵs. In northern parts of the Baltic Sea a warming of the surface layer occurs in the wave included simulations. This in turn reduces the cold bias between simulated and measured data. The warming is primarily caused by sea-state dependent energy flux. Wave induced cooling is mostly observed in near coastal areas and is mainly due to Stokes-Coriolis forcing. The latter triggers effect of intensifying upwellings near the coasts, depending on the direction of the wind. The effect of sea-state dependent momentum flux is predominantly to warm the surface layer. During the summer the wave induced water temperature changes were up to 1 °C.

Verification of land-atmosphere coupling in forecast models, reanalyses and land surface models using flux site observations.

PubMed

Dirmeyer, Paul A; Chen, Liang; Wu, Jiexia; Shin, Chul-Su; Huang, Bohua; Cash, Benjamin A; Bosilovich, Michael G; Mahanama, Sarith; Koster, Randal D; Santanello, Joseph A; Ek, Michael B; Balsamo, Gianpaolo; Dutra, Emanuel; Lawrence, D M

2018-02-01

We confront four model systems in three configurations (LSM, LSM+GCM, and reanalysis) with global flux tower observations to validate states, surface fluxes, and coupling indices between land and atmosphere. Models clearly under-represent the feedback of surface fluxes on boundary layer properties (the atmospheric leg of land-atmosphere coupling), and may over-represent the connection between soil moisture and surface fluxes (the terrestrial leg). Models generally under-represent spatial and temporal variability relative to observations, which is at least partially an artifact of the differences in spatial scale between model grid boxes and flux tower footprints. All models bias high in near-surface humidity and downward shortwave radiation, struggle to represent precipitation accurately, and show serious problems in reproducing surface albedos. These errors create challenges for models to partition surface energy properly and errors are traceable through the surface energy and water cycles. The spatial distribution of the amplitude and phase of annual cycles (first harmonic) are generally well reproduced, but the biases in means tend to reflect in these amplitudes. Interannual variability is also a challenge for models to reproduce. Our analysis illuminates targets for coupled land-atmosphere model development, as well as the value of long-term globally-distributed observational monitoring.

Variations of Connecticut River Water Pathways and Its Water Age: A Coupled Modeling Study

NASA Astrophysics Data System (ADS)

Jia, Y.; Whitney, M. M.

2016-02-01

As the largest freshwater source to the east-west oriented Long Island Sound (LIS), the Connecticut River (CR) delivers water on the north shore near the sound's mouth. The pathways the river water follows through LIS are impacted by river discharge, tides, winds, and complex topography. Using the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System, with passive dyes and age tracers, the main routes of CR water through the estuary and onto the shelf are determined with their corresponding time scales. During a high discharge period, the CR plume occupies the northern half of eastern LIS and extends farther west than during average discharge conditions. Most of the river water inside the central LIS is transported through this surface plume. After being mixed to deeper depths and farther offshore, the river water that is still within LIS is transported westward. During periods of low discharge, freshwater is initially more prevalent between the CR and the LIS mouth. Later, CR water mixed to depths still moves westward, reaching the estuary's head in approximately 3 weeks. Neap tide allows more CR water to quickly escape to the open shelf through Block Island Sound (BIS) while spring tide allows more CR water back into the central LIS at depth. BIS has a uniform water age ranging from 40 to 50 days throughout the water column. Lower discharge leads to older age in BIS. In western LIS, CR water age at depth increases from 50 to 75 days as discharge decreases and is several days younger than water closer to the surface. These results suggest a bottom-in/surface-out transport pattern exists for CR water in LIS for at least part of the year.

Analyzing energy-water exchange dynamics in the Thar desert

NASA Astrophysics Data System (ADS)

Raja, P.; Singh, Nilendu; Srinivas, C. V.; Singhal, Mohit; Chauhan, Pankaj; Singh, Maharaj; Sinha, N. K.

2017-07-01

Regions of strong land-atmosphere coupling will be more susceptible to the hydrological impacts in the intensifying hydrological cycle. In this study, micrometeorological experiments were performed to examine the land-atmosphere coupling strength over a heat low region (Thar desert, NW India), known to influence the Indian summer monsoon (ISM). Within the vortex of Thar desert heat low, energy-water exchange and coupling behavior were studied for 4 consecutive years (2011-2014) based on sub-hourly measurements of radiative-convective flux, state parameters and sub-surface thermal profiles using lead-lag analysis between various E-W balance components. Results indicated a strong (0.11-0.35) but variable monsoon season (July-September) land-atmosphere coupling events. Coupling strength declined with time, becomes negative beyond 10-day lag. Evapotranspiration (LE) influences rainfall at the monthly time-scale (20-40 days). Highly correlated monthly rainfall and LE anomalies (r = 0.55, P < 0.001) suggested a large precipitation memory linked to the local land surface state. Sensible heating (SH) during March and April are more strongly (r = 0.6-0.7) correlated to ISM rainfall than heating during May or June (r = 0.16-0.36). Analyses show strong and weak couplings among net radiation (Rn)-vapour pressure deficit (VPD), LE-VPD and Rn-LE switching between energy-limited to water-limited conditions. Consistently, +ve and -ve residual energy [(dE) = (Rn - G) - (SH + LE)] were associated with regional wet and dry spells respectively with a lead of 10-40 days. Dew deposition (18.8-37.9 mm) was found an important component in the annual surface water balance. Strong association of variation of LE and rainfall was found during monsoon at local-scale and with regional-scale LE (MERRA 2D) but with a lag which was more prominent at local-scale than at regional-scale. Higher pre-monsoon LE at local-scale as compared to low and monotonous variation in regional-scale LE led to hypothesize that excess energy and water vapour brought through advection caused by pre-monsoon rainfall might have been recycled through rainfall to compensate for early part of monsoon rainfall at local-scale. However, long-term measurements and isotope analysis would be able to strengthen this hypothesis. This study would fill the key gaps in the global flux studies and improve understanding on local E-W exchange pathways, responses and feedbacks.

Ocean surface waves in Hurricane Ike (2008) and Superstorm Sandy (2012): Coupled model predictions and observations

NASA Astrophysics Data System (ADS)

Chen, Shuyi S.; Curcic, Milan

2016-07-01

Forecasting hurricane impacts of extreme winds and flooding requires accurate prediction of hurricane structure and storm-induced ocean surface waves days in advance. The waves are complex, especially near landfall when the hurricane winds and water depth varies significantly and the surface waves refract, shoal and dissipate. In this study, we examine the spatial structure, magnitude, and directional spectrum of hurricane-induced ocean waves using a high resolution, fully coupled atmosphere-wave-ocean model and observations. The coupled model predictions of ocean surface waves in Hurricane Ike (2008) over the Gulf of Mexico and Superstorm Sandy (2012) in the northeastern Atlantic and coastal region are evaluated with the NDBC buoy and satellite altimeter observations. Although there are characteristics that are general to ocean waves in both hurricanes as documented in previous studies, wave fields in Ike and Sandy possess unique properties due mostly to the distinct wind fields and coastal bathymetry in the two storms. Several processes are found to significantly modulate hurricane surface waves near landfall. First, the phase speed and group velocities decrease as the waves become shorter and steeper in shallow water, effectively increasing surface roughness and wind stress. Second, the bottom-induced refraction acts to turn the waves toward the coast, increasing the misalignment between the wind and waves. Third, as the hurricane translates over land, the left side of the storm center is characterized by offshore winds over very short fetch, which opposes incoming swell. Landfalling hurricanes produce broader wave spectra overall than that of the open ocean. The front-left quadrant is most complex, where the combination of windsea, swell propagating against the wind, increasing wind-wave stress, and interaction with the coastal topography requires a fully coupled model to meet these challenges in hurricane wave and surge prediction.

Application of MODFLOW’s farm process to California’s Central Valley

USGS Publications Warehouse

Faunt, Claudia; Hanson, Randall T.; Schmid, Wolfgang; Belitz, Kenneth

2008-01-01

landscape processes. The FMP provides coupled simulation of the ground-water and surface-water components of the hydrologic cycle for irrigated and non-irrigated areas. A dynamic allocation of ground-water recharge and ground-water pumping is simulated on the basis of residual crop-water demand after surface-water deliveries and root uptake from shallow ground water. The FMP links with the Streamflow Routing Package SFR1) to facilitate the simulated conveyance of surface-water deliveries. Ground-water Pumpage through both single-aquifer and multi-node wells, irrigation return flow, and variable irrigation efficiencies also are simulated by the FMP. The simulated deliveries and ground-water pumpage in the updated model reflect climatic differences, differences among defined water-balance regions, and changes in the waterdelivery system, during the 1961–2003 simulation period. The model is designed to accept forecasts from Global Climate Models (GCMs) to simulate the potential effects on surface-water delivery, ground-water pumpage, and ground-water storage in response to climate change. The model provides a detailed transient analysis of changes in ground-water availability in relation to climatic variability, urbanization, and changes in irrigated agriculture.

Groundwater-Surface water interaction in agricultural watershed that encompasses dense network of High Capacity wells

NASA Astrophysics Data System (ADS)

Talib, A.; Desai, A. R.

2017-12-01

The Central Sands region of Wisconsin is characterized by productive trout streams, lakes, farmland and forest. However, stream channelization, past wetland drainage, and ground water withdrawals have disrupted the hydrology of this Central Sands region. Climatically driven conditions in last decade (2000-2008) alone are unable to account for the severely depressed water levels. Increased interception and evapotranspiration from afforested areas in central sand Wisconsin may also be culprit for reduced water recharge. Hence, there is need to study the cumulative effects of changing precipitation patterns, groundwater withdrawals, and forest evapotranspiration to improve projections of the future of lake levels and water availability in this region. Here, the SWAT-MODFLOW coupled model approach was applied at large spatio-temporal scale. The coupled model fully integrates a watershed model (SWAT) with a groundwater flow model (MODFLOW). Surface water and ground water flows were simulated integratively at daily time step to estimate the groundwater discharge to the stream network in Central Sands that encompasses high capacity wells. The model was calibrated (2010-2013) and validated (2014-2017) based on streamflow, groundwater extraction, and water table elevation. As the long-term trends in some of the primary drivers is presently ambiguous in Central Sands under future climate, as is the case for total precipitation or timing of precipitation, we relied on a sensitivity student to quantitatively access how primary and secondary drivers may influence future net groundwater recharge. We demonstrate how such an approach could then be coupled with decision-making models to evaluate the effectiveness of groundwater withdrawal policies under a changing climate.

First UAV Measurements of Entrainment Layer Fluxes with Coupled Cloud Property Measurements

NASA Astrophysics Data System (ADS)

Thomas, R. M.; Praveen, P. S.; Wilcox, E. M.; Pistone, K.; Bender, F.; Ramanathan, V.

2012-12-01

This study details entrainment flux measurements made from a lightweight unmanned aerial vehicle (UAV) containing turbulent water vapor flux instrumentation (Thomas et al., 2012). The system was flown for 26 flights during the Cloud, Aerosol, Radiative forcing, Dynamics EXperiment (CARDEX) in the Maldives in March 2012 to study interrelationships between entrainment, aerosols, water budget, cloud microphysics and radiative fluxes in a trade wind cumulus cloud regime. A major advantage of using this lightweight, precision autopiloted UAV system with scientific telemetry is the ability to target small-scale features in the boundary layer, such as an entrainment layer, with minimal aircraft induced disruption. Results are presented from two UAVs flown in stacked formation: one UAV situated in-cloud measuring cloud-droplet size distribution spectra and liquid water content, and another co-located 100m above measuring turbulent properties and entrainment latent heat flux (λEE). We also show latent heat flux and turbulence measurements routinely made at the entrainment layer base and altitudes from the surface up to 4kft. Ratios of λEE to corresponding surface tower values (λES) display a bimodal frequency distribution with ranges 0.22-0.53 and 0.79-1.5, with occasional events >7. Reasons for this distribution are discussed drawing upon boundary layer and free tropospheric dynamics and meteorology, turbulence length scales, surface conditions, and cloud interactions. Latent heat flux profiles are combined with in-cloud UAV Liquid Water Content (LWC) data and surface based Liquid Water Path (LWP) and Precipitable Water Vapor (PWV) measurements to produce observationally constrained vertical water budgets, providing insights into diurnal coupling of λEE and λES. Observed λEE, λES, water budgets, and cloud microphysical responses to entrainment are then contextualized with respect to measured aerosol loading profiles and airmass history.

Implementing Dynamic Root Optimization in Noah-MP for Simulating Phreatophytic Root Water Uptake

NASA Astrophysics Data System (ADS)

Wang, Ping; Niu, Guo-Yue; Fang, Yuan-Hao; Wu, Run-Jian; Yu, Jing-Jie; Yuan, Guo-Fu; Pozdniakov, Sergey P.; Scott, Russell L.

2018-03-01

Widely distributed in arid and semiarid regions, phreatophytic roots extend into the saturated zone and extract water directly from groundwater. In this paper, we implemented a vegetation optimality model of root dynamics (VOM-ROOT) in the Noah land surface model with multiparameterization options (Noah-MP LSM) to model the extraction of groundwater through phreatophytic roots at a riparian site with a hyperarid climate (with precipitation of 35 mm/yr) in northwestern China. VOM-ROOT numerically describes the natural optimization of the root profile in response to changes in subsurface water conditions. The coupled Noah-MP/VOM-ROOT model substantially improves the simulation of surface energy and water fluxes, particularly during the growing season, compared to the prescribed static root profile in the default Noah-MP. In the coupled model, more roots are required to grow into the saturated zone to meet transpiration demand when the groundwater level declines over the growing season. The modeling results indicate that at the study site, the modeled annual transpiration is 472 mm, accounting for 92.3% of the total evapotranspiration. Direct root water uptake from the capillary fringe and groundwater, which is supplied by lateral groundwater flow, accounts for approximately 84% of the total transpiration. This study demonstrates the importance of implementing a dynamic root scheme in a land surface model for adequately simulating phreatophytic root water uptake and the associated latent heat flux.

Direct measurements of wind-water momentum coupling in a marsh with emergent vegetation and implications for gas transfer estimates

NASA Astrophysics Data System (ADS)

Tse, I.; Poindexter, C.; Variano, E. A.

2013-12-01

Among the numerous ecological benefits of restoring wetlands is carbon sequestration. As emergent vegetation thrive, atmospheric CO2 is removed and converted into biomass that gradually become additional soil. Forecasts and management for these systems rely on accurate knowledge of gas exchange between the atmosphere and the wetland surface waters. Our previous work showed that the rate of gas transfer across the air-water interface is affected by the amount of water column mixing caused by winds penetrating through the plant canopy. Here, we present the first direct measurements of wind-water momentum coupling made within a tule marsh. This work in Twitchell Island in the California Delta shows how momentum is imparted into the water from wind stress and that this wind stress interacts with the surface waters in an interesting way. By correlating three-component velocity signals from a sonic anemometer placed within the plant canopy with data from a novel Volumetric Particle Imager (VoPI) placed in the water, we measure the flux of kinetic energy through the plant canopy and the time-scale of the response. We also use this unique dataset to estimate the air-water drag coefficient using an adjoint method.

Quantum calculations of the IR spectrum of liquid water using ab initio and model potential and dipole moment surfaces and comparison with experiment.

PubMed

Liu, Hanchao; Wang, Yimin; Bowman, Joel M

2015-05-21

The calculation and characterization of the IR spectrum of liquid water have remained a challenge for theory. In this paper, we address this challenge using a combination of ab initio approaches, namely, a quantum treatment of IR spectrum using the ab initio WHBB water potential energy surface and a refined ab initio dipole moment surface. The quantum treatment is based on the embedded local monomer method, in which the three intramolecular modes of each embedded H2O monomer are fully coupled and also coupled singly to each of six intermolecular modes. The new dipole moment surface consists of a previous spectroscopically accurate 1-body dipole moment surface and a newly fitted ab initio intrinsic 2-body dipole moment. A detailed analysis of the new dipole moment surface in terms of the coordinate dependence of the effective atomic charges is done along with tests of it for the water dimer and prism hexamer double-harmonic spectra against direct ab initio calculations. The liquid configurations are taken from previous molecular dynamics calculations of Skinner and co-workers, using the TIP4P plus E3B rigid monomer water potential. The IR spectrum of water at 300 K in the range of 0-4000 cm(-1) is calculated and compared with experiment, using the ab initio WHBB potential and new ab initio dipole moment, the q-TIP4P/F potential, which has a fixed-charged description of the dipole moment, and the TTM3-F potential and dipole moment surfaces. The newly calculated ab initio spectrum is in very good agreement with experiment throughout the above spectral range, both in band positions and intensities. This contrasts to results with the other potentials and dipole moments, especially the fixed-charge q-TIP4P/F model, which gives unrealistic intensities. The calculated ab initio spectrum is analyzed by examining the contribution of various transitions to each band.

Quantum calculations of the IR spectrum of liquid water using ab initio and model potential and dipole moment surfaces and comparison with experiment

NASA Astrophysics Data System (ADS)

Liu, Hanchao; Wang, Yimin; Bowman, Joel M.

2015-05-01

The calculation and characterization of the IR spectrum of liquid water have remained a challenge for theory. In this paper, we address this challenge using a combination of ab initio approaches, namely, a quantum treatment of IR spectrum using the ab initio WHBB water potential energy surface and a refined ab initio dipole moment surface. The quantum treatment is based on the embedded local monomer method, in which the three intramolecular modes of each embedded H2O monomer are fully coupled and also coupled singly to each of six intermolecular modes. The new dipole moment surface consists of a previous spectroscopically accurate 1-body dipole moment surface and a newly fitted ab initio intrinsic 2-body dipole moment. A detailed analysis of the new dipole moment surface in terms of the coordinate dependence of the effective atomic charges is done along with tests of it for the water dimer and prism hexamer double-harmonic spectra against direct ab initio calculations. The liquid configurations are taken from previous molecular dynamics calculations of Skinner and co-workers, using the TIP4P plus E3B rigid monomer water potential. The IR spectrum of water at 300 K in the range of 0-4000 cm-1 is calculated and compared with experiment, using the ab initio WHBB potential and new ab initio dipole moment, the q-TIP4P/F potential, which has a fixed-charged description of the dipole moment, and the TTM3-F potential and dipole moment surfaces. The newly calculated ab initio spectrum is in very good agreement with experiment throughout the above spectral range, both in band positions and intensities. This contrasts to results with the other potentials and dipole moments, especially the fixed-charge q-TIP4P/F model, which gives unrealistic intensities. The calculated ab initio spectrum is analyzed by examining the contribution of various transitions to each band.

A conceptual model for the analysis of multi-stressors in linked groundwater-surface water systems.

PubMed

Kaandorp, Vince P; Molina-Navarro, Eugenio; Andersen, Hans E; Bloomfield, John P; Kuijper, Martina J M; de Louw, Perry G B

2018-06-15

Groundwater and surface water are often closely coupled and are both under the influence of multiple stressors. Stressed groundwater systems may lead to a poor ecological status of surface waters but to date no conceptual framework to analyse linked multi-stressed groundwater - surface water systems has been developed. In this paper, a framework is proposed showing the effect of groundwater on surface waters in multiple stressed systems. This framework will be illustrated by applying it to four European catchments, the Odense, Denmark, the Regge and Dinkel, Netherlands, and the Thames, UK, and by assessing its utility in analysing the propagation or buffering of multi-stressors through groundwater to surface waters in these catchments. It is shown that groundwater affects surface water flow, nutrients and temperature, and can both propagate stressors towards surface waters and buffer the effect of stressors in space and time. The effect of groundwater on drivers and states depends on catchment characteristics, stressor combinations, scale and management practises. The proposed framework shows how groundwater in lowland catchments acts as a bridge between stressors and their effects within surface waters. It shows water managers how their management areas might be influenced by groundwater, and helps them to include this important, but often overlooked part of the water cycle in their basin management plans. The analysis of the study catchments also revealed a lack of data on the temperature of both groundwater and surface water, while it is an important parameter considering future climate warming. Copyright © 2018. Published by Elsevier B.V.

Using a spatially-distributed hydrologic biogeochemistry model with nitrogen transport to study the spatial variation of carbon stocks and fluxes in a Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Shi, Y.; Eissenstat, D. M.; He, Y.; Davis, K. J.

2017-12-01

Most current biogeochemical models are 1-D and represent one point in space. Therefore, they cannot resolve topographically driven land surface heterogeneity (e.g., lateral water flow, soil moisture, soil temperature, solar radiation) or the spatial pattern of nutrient availability. A spatially distributed forest biogeochemical model with nitrogen transport, Flux-PIHM-BGC, has been developed by coupling a 1-D mechanistic biogeochemical model Biome-BGC (BBGC) with a spatially distributed land surface hydrologic model, Flux-PIHM, and adding an advection dominated nitrogen transport module. Flux-PIHM is a coupled physically based model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model, and is augmented by adding a topographic solar radiation module. Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as land surface heterogeneities caused by topography. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1-D BBGC model, while nitrogen is transported among model grids via surface and subsurface water flow. In each grid, Flux-PIHM provides BBGC with soil moisture, soil temperature, and solar radiation, while BBGC provides Flux-PIHM with spatially-distributed leaf area index. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna/Shale Hills Critical Zone Observatory. The model-predicted aboveground vegetation carbon and soil carbon distributions generally agree with the macro patterns observed within the watershed. The importance of abiotic variables (including soil moisture, soil temperature, solar radiation, and soil mineral nitrogen) in predicting aboveground carbon distribution is calculated using a random forest. The result suggests that the spatial pattern of aboveground carbon is controlled by the distribution of soil mineral nitrogen. A Flux-PIHM-BGC simulation without the nitrogen transport module is also executed. The model without nitrogen transport fails in predicting the spatial patterns of vegetation carbon, which indicates the importance of having a nitrogen transport module in spatially distributed ecohydrologic modeling.

Coupled surface and subsurface flow modeling of natural hillslopes in the Aburrá Valley (Medellín, Colombia)

NASA Astrophysics Data System (ADS)

Blessent, Daniela; Barco, Janet; Temgoua, André Guy Tranquille; Echeverrri-Ramirez, Oscar

2017-03-01

Numerical results are presented of surface-subsurface water modeling of a natural hillslope located in the Aburrá Valley, in the city of Medellín (Antioquia, Colombia). The integrated finite-element hydrogeological simulator HydroGeoSphere is used to conduct transient variably saturated simulations. The objective is to analyze pore-water pressure and saturation variation at shallow depths, as well as volumes of water infiltrated in the porous medium. These aspects are important in the region of study, which is highly affected by soil movements, especially during the high-rain seasons that occur twice a year. The modeling exercise considers rainfall events that occurred between October and December 2014 and a hillslope that is currently monitored because of soil instability problems. Simulation results show that rainfall temporal variability, mesh resolution, coupling length, and the conceptual model chosen to represent the heterogeneous soil, have a noticeable influence on results, particularly for high rainfall intensities. Results also indicate that surface-subsurface coupled modeling is required to avoid unrealistic increase in hydraulic heads when high rainfall intensities cause top-down saturation of soil. This work is a first effort towards fostering hydrogeological modeling expertise that may support the development of monitoring systems and early landslide warning in a country where the rainy season is often the cause of hydrogeological tragedies associated with landslides, mud flow or debris flow.

Exploring the Influence of Topography on Belowground C Processes Using a Coupled Hydrologic-Biogeochemical Model

NASA Astrophysics Data System (ADS)

Shi, Y.; Davis, K. J.; Eissenstat, D. M.; Kaye, J. P.; Duffy, C.; Yu, X.; He, Y.

2014-12-01

Belowground carbon processes are affected by soil moisture and soil temperature, but current biogeochemical models are 1-D and cannot resolve topographically driven hill-slope soil moisture patterns, and cannot simulate the nonlinear effects of soil moisture on carbon processes. Coupling spatially-distributed physically-based hydrologic models with biogeochemical models may yield significant improvements in the representation of topographic influence on belowground C processes. We will couple the Flux-PIHM model to the Biome-BGC (BBGC) model. Flux-PIHM is a coupled physically-based land surface hydrologic model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model. Because PIHM is capable of simulating lateral water flow and deep groundwater, Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as the land surface heterogeneities caused by topography. The coupled Flux-PIHM-BBGC model will be tested at the Susquehanna/Shale Hills critical zone observatory (SSHCZO). The abundant observations, including eddy covariance fluxes, soil moisture, groundwater level, sap flux, stream discharge, litterfall, leaf area index, above ground carbon stock, and soil carbon efflux, make SSHCZO an ideal test bed for the coupled model. In the coupled model, each Flux-PIHM model grid will couple a BBGC cell. Flux-PIHM will provide BBGC with soil moisture and soil temperature information, while BBGC provides Flux-PIHM with leaf area index. Preliminary results show that when Biome- BGC is driven by PIHM simulated soil moisture pattern, the simulated soil carbon is clearly impacted by topography.

Hydromechanical coupling in fractured rock masses: mechanisms and processes of selected case studies

NASA Astrophysics Data System (ADS)

Zangerl, Christian

2015-04-01

Hydromechanical (HM) coupling in fractured rock play an important role when events including dam failures, landslides, surface subsidences due to water withdrawal or drainage, injection-induced earthquakes and others are analysed. Generally, hydromechanical coupling occurs when a rock mass contain interconnected pores and fractures which are filled with water and pore/fracture pressures evolves. In the on hand changes in the fluid pressure can lead to stress changes, deformations and failures of the rock mass. In the other hand rock mass stress changes and deformations can alter the hydraulic properties and fluid pressures of the rock mass. Herein well documented case studies focussing on surface subsidence due to water withdrawal, reversible deformations of large-scale valley flanks and failure as well as deformation processes of deep-seated rock slides in fractured rock masses are presented. Due to pore pressure variations HM coupling can lead to predominantly reversible rock mass deformations. Such processes can be considered by the theory of poroelasticity. Surface subsidence reaching magnitudes of few centimetres and are caused by water drainage into deep tunnels are phenomenas which can be assigned to processes of poroelasticity. Recently, particular focus was given on large tunnelling projects to monitor and predict surface subsidence in fractured rock mass in oder to avoid damage of surface structures such as dams of large reservoirs. It was found that surface subsidence due to tunnel drainage can adversely effect infrastructure when pore pressure drawdown is sufficiently large and spatially extended and differential displacements which can be amplified due to topographical effects e.g. valley closure are occurring. Reversible surface deformations were also ascertained on large mountain slopes and summits with the help of precise deformation measurements i.e. permanent GPS or episodic levelling/tacheometric methods. These reversible deformations are often in the range of millimetres to a very few centimetres and can be linked to annual groundwater fluctuations. Due to pore pressure variations HM coupling can influence seepage forces and effective stresses in the rock mass. Effective stress changes can adversely affect the stability and deformation behaviour of deep-seated rock slides by influencing the shear strength or the time dependent (viscous) material behaviour of the basal shear zone. The shear strength of active shear zones is often reasonably well described by Coulomb's law. In Coulomb's law the operative normal stresses to the shear surface/zone are effective stresses and hence pore pressures which should be taken into account reduces the shear strength. According to the time dependent material behaviour a few effective stress based viscous models exists which are able to consider pore pressures. For slowly moving rock slides HM coupling could be highly relevant when low-permeability clayey-silty shear zones (fault gouges) are existing. An important parameters therefore is the hydraulic diffusivity, which is controlled by the permeability and fluid-pore compressibility of the shear zone, and by fluid viscosity. Thus time dependent pore pressure diffusion in the shear zone can either control the stability condition or the viscous behaviour (creep) of the rock slide. Numerous cases studies show that HM coupling can effect deformability, shear strength and time dependent behaviour of fractured rock masses. A process-based consideration can be important to avoid unexpected impacts on infrastructures and to understand complex rock mass as well rock slide behaviour.

Global off-line evaluation of the ISBA-TRIP continental hydrological system used in the CNRM-CM6 climate model for the next CMIP6 exercise

NASA Astrophysics Data System (ADS)

Decharme, Bertrand; Vergnes, Jean-Pierre; Minvielle, Marie; Colin, Jeanne; Delire, Christine

2016-04-01

The land surface hydrology represents an active component of the climate system. It is likely to influence the water and energy exchanges at the land surface, the ocean salinity and temperature at the mouth of the largest rivers, and the climate at least at the regional scale. In climate models, the continental hydrology is simulated via Land Surface Models (LSM), which compute water and energy budgets at the surface, coupled to River Routing Model (RRM), which convert the runoff simulated by the LSMs into river discharge in order to transfer the continental fresh water into the oceans and then to close the global hydrological cycle. Validating these Continental Hydrological Systems (CHS) at the global scale is therefore a crucial task, which requires off-line simulations driven by realistic atmospheric fluxes to avoid the systematic biases commonly found in the atmospheric models. In the CNRM-CM6 climate model of Météo-France, that will be used for the next Coupled Climate Intercomparison Project phase 6 (CMIP6) exercise, the land surface hydrology is simulated using the ISBA-TRIP CHS coupled via the OASIS-MCT coupler. The ISBA LSM solves explicitly the one dimensional Fourier law for soil temperature and the mixed form of the Richards equation for soil moisture using a 14-layers discretization over 12m depths. For the snowpack, a discretization using 12 layers allows the explicit representation of some snow key processes as its viscosity, its compaction due to wind, its age and its albedo on the visible and near infrared spectra. The TRIP RRM uses a global river channel network at 0.5° resolution. It is based on a three prognostic equations for the surface stream water, the seasonal floodplains, and the groundwater. The streamflow velocity is computed using the Maning's formula. The floodplain reservoir fills when the river height exceeds the river bankfull height and vice-versa. The flood interacts with the ISBA soil hydrology through infiltration and with the overlying atmosphere through precipitation interception and free water surface evaporation. Finally, the groundwater scheme is based on the two-dimensional groundwater flow equation for the piezometric head. Its coupling with ISBA permits to account for the presence of a water table under the soil moisture column allowing upward capillarity fluxes into the soil. In this study, we will present the off-line evaluation at the global scale of the ISBA-TRIP CHS over a recent period (1979-2010). The system will be compared to observations such as GRACE (Gravity Recovery and Climate Experiment) terrestrial water storage data, snow and permafrost extents from NSIDC (National Snow and Ice Data Center), or in-situ river discharge measurements from several sources. In addition we will also explore the impacts on the simulated water budget to account for some processes such as upward capillarity fluxes from groundwaters or seasonal floodplains. At last, it is envisaged to discuss some results about land/atmosphere interactions induced by these processes in the CNRM-CM6 climate model.

Application of ICP-OES for Evaluating Energy Extraction and Production Wastewater Discharge Impacts on Surface Waters in Western Pennsylvania

EPA Science Inventory

Oil and gas extraction and coal-fired electrical power generating stations produce wastewaters that are treated and discharged to rivers in Western Pennsylvania with public drinking water system (PDWS) intakes. Inductively coupled plasma optical emission spectroscopy (ICP-OES) w...

Coupling diffusion and maximum entropy models to estimate thermal inertia

USDA-ARS?s Scientific Manuscript database

Thermal inertia is a physical property of soil at the land surface related to water content. We have developed a method for estimating soil thermal inertia using two daily measurements of surface temperature, to capture the diurnal range, and diurnal time series of net radiation and specific humidi...

Dynamic Kinetics of Nitrogen Cycle in Groundwater-Surface Water Interaction Zone at Hanford Site

NASA Astrophysics Data System (ADS)

Liu, Y.; Liu, C.; Liu, Y.; Xu, F.; Yan, A.; Shi, L.; Zachara, J. M.; Gao, Y.; Qian, W.; Nelson, W.; Fredrickson, J.; Zhong, L.; Thompson, C.

2015-12-01

Nitrogen cycle carried out by microbes is an important geobiological process that has global implications for carbon and nitrogen cycling and climate change. This presentation describes a study of nitrogen cycle in groundwater-surface water interaction zone (GSIZ) at the US Department of Energy's Hanford Site. Groundwater at Hanford sites has long been documented with nitrate contamination. Nearby Columbia River stage changes of up to 3 m every day because of daily discharge fluctuation from upstream Priest Rapids Dam; resulting an exchange of groundwater and surface water in a short time period. Yet, nitrogen cycle in the GSIZ at Hanford Site remains unclear. Column studies have been used to identify nitrogen metabolism pathways and investigate kinetics of nitrogen cycle in groundwater saturated zone, surface water saturated zone, and GSIZ. Functional gene and protein abundances were determined by qPCR and PRISM-SRM (high-pressure, high-resolution separations coupled with intelligent selection and multiplexing for sensitive selected reaction monitoring) to identify key enzymatic reactions and metabolic pathways of nitrogen cycle. The results showed that dissimilatory nitrate reduction to ammonium (DNRA) competed with denitrification under anaerobic conditions, reducing 30% of NO3- to NH4+, a cation strongly retained on the sediments. As dissolved oxygen intruded the anaerobic zone with river water, NH4+ was oxidized to NO3-, increasing the mobility of NO3-. Multiplicative Monod models were established to describe nitrogen cycle in columns fed with O2 depleted synthetic groundwater and O2 saturated synthetic river water, respectively. The two models were then coupled to predict the dynamic kinetics of nitrogen cycle in GSIZ.

Role of Subsurface Physics in the Assimilation of Surface Soil Moisture Observations

NASA Technical Reports Server (NTRS)

Reichle, R. H.

2010-01-01

Root zone soil moisture controls the land-atmosphere exchange of water and energy and exhibits memory that may be useful for climate prediction at monthly scales. Assimilation of satellite-based surface soil moisture observations into a land surface model is an effective way to estimate large-scale root zone soil moisture. The propagation of surface information into deeper soil layers depends on the model-specific representation of subsurface physics that is used in the assimilation system. In a suite of experiments we assimilate synthetic surface soil moisture observations into four different models (Catchment, Mosaic, Noah and CLM) using the Ensemble Kalman Filter. We demonstrate that identical twin experiments significantly overestimate the information that can be obtained from the assimilation of surface soil moisture observations. The second key result indicates that the potential of surface soil moisture assimilation to improve root zone information is higher when the surface to root zone coupling is stronger. Our experiments also suggest that (faced with unknown true subsurface physics) overestimating surface to root zone coupling in the assimilation system provides more robust skill improvements in the root zone compared with underestimating the coupling. When CLM is excluded from the analysis, the skill improvements from using models with different vertical coupling strengths are comparable for different subsurface truths. Finally, the skill improvements through assimilation were found to be sensitive to the regional climate and soil types.

Fast screening and quantitation of microcystins in microalgae dietary supplement products and water by liquid chromatography coupled to time of flight mass spectrometry.

PubMed

Ortelli, Didier; Edder, Patrick; Cognard, Emmanuelle; Jan, Philippe

2008-06-09

Cyanobacteria, commonly called "blue-green algae", may accumulate in surface water supplies as "blooms" and may concentrate on the surface as blue-green "scums". Some species of cyanobacteria produce toxins and are of relevance to water supplies and to microalgae dietary supplements. To ensure the safety of drinking water and blue-green algae products, analyses are the only way to determine the presence or absence of toxins. This paper shows the use of ultra performance liquid chromatography (UPLC) coupled to orthogonal acceleration time of flight (TOF) mass spectrometry for the detection and quantitation of microcystins. The method presented is very sensitive, simple, fast, robust and did not require fastidious clean-up step. Limits of detection of 0.1 microg L(-1) in water and 0.1-0.2 microg g(-1) in microalgae samples were achieved. Method performances were satisfactory and appropriate for monitoring of water and dietary supplements. The method was applied in routine to samples taken from Swiss market or buy on internet website. Among 19 samples, six showed the presence of microcystins LR and LA at harmful levels.

Thermal Characteristics of ThermoBrachytherapy Surface Applicators (TBSA) for Treating Chestwall Recurrence

PubMed Central

Arunachalam, K.; Maccarini, P. F.; Craciunescu, O. I.; Schlorff, J. L.; Stauffer, P. R.

2010-01-01

Purpose To study temperature and thermal dose distributions of ThermoBrachytherapy Surface Applicators (TBSA) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial disease. Methods A steady state thermodynamics model coupled with the fluid dynamics of water bolus and electromagnetic radiation of hyperthermia applicator is used to characterize the temperature distributions achievable with TBSA applicators in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm2) and L-shaped (875 cm2) TBSA. The SAR distribution in tissue and fluid flow distribution inside the Dual-Input Dual-Output (DIDO) water bolus are coupled to solve the steady state temperature and thermal dose distributions of rectangular TBSA (R-TBSA) for superficial tumor targets extending 10–15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (Tb=38–43°C), water flow rate (Qb=2–4 L/min) and tumor blood perfusion (ωb=2–5 kg/m3/s) to characterize their influence on thermal dosimetry. Results Steady state SAR patterns of R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at 2 L/min water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (Tb) to be the most influential factor on thermal dosimetry. A 42 °C water bolus was observed to be the optimal choice for superficial tumors extending 10–15 mm from the surface even under significant blood perfusion. Lower bolus temperature may be chosen to reduce thermal enhancement ratio (TER) in the most sensitive skin where maximum radiation dose is delivered and to extend thermal enhancement of radiation dose deeper. Conclusion This computational study indicates that well-localized elevation of tumor target temperature to 40–44 °C can be accomplished by large surface-conforming TBSA applicators using appropriate selection of coupling bolus temperature. PMID:20224154

Validation of newly designed regional earth system model (RegESM) for Mediterranean Basin

NASA Astrophysics Data System (ADS)

Turuncoglu, Ufuk Utku; Sannino, Gianmaria

2017-05-01

We present a validation analysis of a regional earth system model system (RegESM) for the Mediterranean Basin. The used configuration of the modeling system includes two active components: a regional climate model (RegCM4) and an ocean modeling system (ROMS). To assess the performance of the coupled modeling system in representing the climate of the basin, the results of the coupled simulation (C50E) are compared to the results obtained by a standalone atmospheric simulation (R50E) as well as several observation datasets. Although there is persistent cold bias in fall and winter, which is also seen in previous studies, the model reproduces the inter-annual variability and the seasonal cycles of sea surface temperature (SST) in a general good agreement with the available observations. The analysis of the near-surface wind distribution and the main circulation of the sea indicates that the coupled model can reproduce the main characteristics of the Mediterranean Sea surface and intermediate layer circulation as well as the seasonal variability of wind speed and direction when it is compared with the available observational datasets. The results also reveal that the simulated near-surface wind speed and direction have poor performance in the Gulf of Lion and surrounding regions that also affects the large positive SST bias in the region due to the insufficient horizontal resolution of the atmospheric component of the coupled modeling system. The simulated seasonal climatologies of the surface heat flux components are also consistent with the CORE.2 and NOCS datasets along with the overestimation in net long-wave radiation and latent heat flux (or evaporation, E), although a large observational uncertainty is found in these variables. Also, the coupled model tends to improve the latent heat flux by providing a better representation of the air-sea interaction as well as total heat flux budget over the sea. Both models are also able to reproduce the temporal evolution of the inter-annual anomaly of surface air temperature and precipitation (P) over defined sub-regions. The Mediterranean water budget (E, P and E-P) estimates also show that the coupled model has high skill in the representation of water budget of the Mediterranean Sea. To conclude, the coupled model reproduces climatological land surface fields and the sea surface variables in the range of observation uncertainty and allow studying air-sea interaction and main regional climate characteristics of the basin.

Bacterial community composition and structure in an Urban River impacted by different pollutant sources.

PubMed

Ibekwe, A Mark; Ma, Jincai; Murinda, Shelton E

2016-10-01

Microbial communities in terrestrial fresh water are diverse and dynamic in composition due to different environmental factors. The goal of this study was to undertake a comprehensive analysis of bacterial composition along different rivers and creeks and correlate these to land-use practices and pollutant sources. Here we used 454 pyrosequencing to determine the total bacterial community composition, and bacterial communities that are potentially of fecal origin, and of relevance to water quality assessment. The results were analyzed using UniFrac coupled with principal coordinate analysis (PCoA) to compare diversity, abundance, and community composition. Detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to correlate bacterial composition in streams and creeks to different environmental parameters impacting bacterial communities in the sediment and surface water within the watershed. Bacteria were dominated by the phyla Proteobacteria, Bacteroidetes, Acidobacteria, and Actinobacteria, with Bacteroidetes significantly (P<0.001) higher in all water samples than sediment, where as Acidobacteria and Actinobacteria where significantly higher (P<0.05) in all the sediment samples than surface water. Overall results, using the β diversity measures, coupled with PCoA and DCA showed that bacterial composition in sediment and surface water was significantly different (P<0.001). Also, there were differences in bacterial community composition between agricultural runoff and urban runoff based on parsimony tests using 454 pyrosequencing data. Fecal indicator bacteria in surface water along different creeks and channels were significantly correlated with pH (P<0.01), NO2 (P<0.03), and NH4N (P<0.005); and in the sediment with NO3 (P<0.015). Our results suggest that microbial community compositions were influenced by several environmental factors, and pH, NO2, and NH4 were the major environmental factors driving FIB in surface water based on CCA analysis, while NO3 was the only factor in sediment. Published by Elsevier B.V.

A convenient catalyst for aqueous and protein Suzuki-Miyaura cross-coupling.

PubMed

Chalker, Justin M; Wood, Charlotte S C; Davis, Benjamin G

2009-11-18

A phosphine-free palladium catalyst for aqueous Suzuki-Miyaura cross-coupling is presented. The catalyst is active enough to mediate hindered, ortho-substituted biaryl couplings but mild enough for use on peptides and proteins. The Suzuki-Miyaura couplings on protein substrates are the first to proceed in useful conversions. Notably, hydrophobic aryl and vinyl groups can be transferred to the protein surface without the aid of organic solvent since the aryl- and vinylboronic acids used in the coupling are water-soluble as borate salts. The convenience and activity of this catalyst prompts use in both general synthesis and bioconjugation.

Coupled land surface/hydrologic/atmospheric models

NASA Technical Reports Server (NTRS)

Pielke, Roger; Steyaert, Lou; Arritt, Ray; Lahtakia, Mercedes; Smith, Chris; Ziegler, Conrad; Soong, Su Tzai; Avissar, Roni; Wetzel, Peter; Sellers, Piers

1993-01-01

The topics covered include the following: prototype land cover characteristics data base for the conterminous United States; surface evapotranspiration effects on cumulus convection and implications for mesoscale models; the use of complex treatment of surface hydrology and thermodynamics within a mesoscale model and some related issues; initialization of soil-water content for regional-scale atmospheric prediction models; impact of surface properties on dryline and MCS evolution; a numerical simulation of heavy precipitation over the complex topography of California; representing mesoscale fluxes induced by landscape discontinuities in global climate models; emphasizing the role of subgrid-scale heterogeneity in surface-air interaction; and problems with modeling and measuring biosphere-atmosphere exchanges of energy, water, and carbon on large scales.

A process-level attribution of the annual cycle of surface temperature over the Maritime Continent

NASA Astrophysics Data System (ADS)

Li, Yana; Yang, Song; Deng, Yi; Hu, Xiaoming; Cai, Ming

2017-12-01

The annual cycle of the surface temperature over the Maritime Continent (MC) is characterized by two periods of rapid warming in March-April and September-October, respectively, and a period of rapid cooling in June-July. Based upon an analysis of energy balance within individual atmosphere-surface columns, the seasonal variations of surface temperature in the MC are partitioned into partial temperature changes associated with various radiative and non-radiative (dynamical) processes. The seasonal variations in direct solar forcing and surface latent heat flux show the largest positive contributions to the annual cycle of MC surface temperature while the changes in oceanic dynamics (including ocean heat content change) work against the temperature changes related to the annual cycle. The rapid warming in March-April is mainly a result of the changes in atmospheric quick processes and ocean-atmosphere coupling such as water vapor, surface latent heat flux, clouds, and atmospheric dynamics while the contributions from direct solar forcing and oceanic dynamics are negative. This feature is in contrast to that associated with the warming in September-October, which is driven mainly by the changes in solar forcing with a certain amount of contributions from water vapor and latent heat flux change. More contribution from atmospheric quick processes and ocean-atmosphere coupling in March-April coincides with the sudden northward movement of deep convection belt, while less contribution from these quick processes and coupling is accompanied with the convection belt slowly moving southward. The main contributors to the rapid cooling in June-July are the same as those to the rapid warming in March-April, and the cooling is also negatively contributed by direct solar forcing and oceanic dynamics. The changes in water vapor in all three periods contribute positively to the change in total temperature and they are associated with the change in the location of the center of large-scale moisture convergence during the onset and demise stages of the East Asian summer monsoon.

Coupled Surface and Groundwater Hydrological Modeling in a Changing Climate.

PubMed

Sridhar, Venkataramana; Billah, Mirza M; Hildreth, John W

2017-11-09

Many current watershed modeling efforts now incorporate surface water and groundwater for managing water resources since the exchanges between groundwater and surface water need a special focus considering the changing climate. The influence of groundwater dynamics on water and energy balance components is investigated in the Snake River Basin (SRB) by coupling the Variable Infiltration Capacity (VIC) and MODFLOW models (VIC-MF) for the period of 1986 through 2042. A 4.4% increase in base flows and a 10.3% decrease in peak flows are estimated by VIC-MF compared to the VIC model in SRB. The VIC-MF model shows significant improvement in the streamflow simulation (Nash-Sutcliffe efficiency [NSE] of 0.84) at King Hill, where the VIC model could not capture the effect of spring discharge in the streamflow simulation (NSE of -0.30); however, the streamflow estimates show an overall decreasing trend. Two climate scenarios representing median and high radiative-forcings such as representative concentration pathways 4.5 and 8.5 show an average increase in the water table elevations between 2.1 and 2.6 m (6.9 and 8.5 feet) through the year 2042. The spatial patterns of these exchanges show a higher groundwater elevation of 15 m (50 feet) in the downstream area and a lower elevation of up to 3 m (10 feet) in the upstream area. Broadly, this study supports results of previous work demonstrating that integrated assessment of groundwater-surface water enables stakeholders to balance pumping, recharge and base flow needs and to manage the watersheds that are subjected to human pressures more sustainably. © 2017, National Ground Water Association.

Field Investigation and Modeling Development for Hydrological and Carbon Cycles in Southwest Karst Region of China

NASA Astrophysics Data System (ADS)

Hu, X. B.

2017-12-01

It is required to understanding water cycle and carbon cycle processes for water resource management and pollution prevention and global warming influence in southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models. Our study focus on the karst springshed in Mao village, the mechanisms coupling carbon cycle and water cycle are explored. This study provides basic theory and simulation method for water resource management and groundwater pollution prevention in China karst region.

The Mars Dust Cycle: Investigating the Effects of Radiatively Active Water Ice Clouds on Surface Stresses and Dust Lifting Potential with the NASA Ames Mars General Circulation Model

NASA Technical Reports Server (NTRS)

Kahre, Melinda A.; Hollingsworth, Jeffery

2012-01-01

The dust cycle is a critically important component of Mars' current climate system. Dust is present in the atmosphere of Mars year-round but the dust loading varies with season in a generally repeatable manner. Dust has a significant influence on the thermal structure of the atmosphere and thus greatly affects atmospheric circulation. The dust cycle is the most difficult of the three climate cycles (CO2, water, and dust) to model realistically with general circulation models. Until recently, numerical modeling investigations of the dust cycle have typically not included the effects of couplings to the water cycle through cloud formation. In the Martian atmosphere, dust particles likely provide the seed nuclei for heterogeneous nucleation of water ice clouds. As ice coats atmospheric dust grains, the newly formed cloud particles exhibit different physical and radiative characteristics. Thus, the coupling between the dust and water cycles likely affects the distributions of dust, water vapor and water ice, and thus atmospheric heating and cooling and the resulting circulations. We use the NASA Ames Mars GCM to investigate the effects of radiatively active water ice clouds on surface stress and the potential for dust lifting. The model includes a state-of-the-art water ice cloud microphysics package and a radiative transfer scheme that accounts for the radiative effects of CO2 gas, dust, and water ice clouds. We focus on simulations that are radiatively forced by a prescribed dust map, and we compare simulations that do and do not include radiatively active clouds. Preliminary results suggest that the magnitude and spatial patterns of surface stress (and thus dust lifting potential) are substantial influenced by the radiative effects of water ice clouds.

Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover

PubMed Central

Stegen, James C.; Fredrickson, James K.; Wilkins, Michael J.; Konopka, Allan E.; Nelson, William C.; Arntzen, Evan V.; Chrisler, William B.; Chu, Rosalie K.; Danczak, Robert E.; Fansler, Sarah J.; Kennedy, David W.; Resch, Charles T.; Tfaily, Malak

2016-01-01

Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater–surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater–surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds. PMID:27052662

Groundwater-surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover.

PubMed

Stegen, James C; Fredrickson, James K; Wilkins, Michael J; Konopka, Allan E; Nelson, William C; Arntzen, Evan V; Chrisler, William B; Chu, Rosalie K; Danczak, Robert E; Fansler, Sarah J; Kennedy, David W; Resch, Charles T; Tfaily, Malak

2016-04-07

Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater-surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater-surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds.

Development of a 3D Soil-Plant-Atmosphere Continuum (SPAC) coupled to a Land Surface Model

NASA Astrophysics Data System (ADS)

Bisht, G.; Riley, W. J.; Lorenzetti, D.; Tang, J.

2015-12-01

Exchange of water between the atmosphere and biosphere via evapotranspiration (ET) influences global hydrological, energy, and biogeochemical cycles. Isotopic analysis has shown that evapotranspiration over the continents is largely dominated by transpiration. Water is taken up from soil by plant roots, transported through the plant's vascular system, and evaporated from the leaves. Yet current Land Surface Models (LSMs) integrated into Earth System Models (ESMs) treat plant roots as passive components. These models distribute the ET sink vertically over the soil column, neglect the vertical pressure distribution along the plant vascular system, and assume that leaves can directly access water from any soil layer within the root zone. Numerous studies have suggested that increased warming due to climate change will lead drought and heat-induced tree mortality. A more mechanistic treatment of water dynamics in the soil-plant-atmosphere continuum (SPAC) is essential for investigating the fate of ecosystems under a warmer climate. In this work, we describe a 3D SPAC model that can be coupled to a LSM. The SPAC model uses the variably saturated Richards equations to simulate water transport. The model uses individual governing equations and constitutive relationships for the various SPAC components (i.e., soil, root, and xylem). Finite volume spatial discretization and backward Euler temporal discretization is used to solve the SPAC model. The Portable, Extensible Toolkit for Scientific Computation (PETSc) is used to numerically integrate the discretized system of equations. Furthermore, PETSc's multi-physics coupling capability (DMComposite) is used to solve the tightly coupled system of equations of the SPAC model. Numerical results are presented for multiple test problems.

Evaluation of an Infiltration Model with Microchannels

NASA Astrophysics Data System (ADS)

Garcia-Serrana, M.; Gulliver, J. S.; Nieber, J. L.

2015-12-01

This research goal is to develop and demonstrate the means by which roadside drainage ditches and filter strips can be assigned the appropriate volume reduction credits by infiltration. These vegetated surfaces convey stormwater, infiltrate runoff, and filter and/or settle solids, and are often placed along roads and other impermeable surfaces. Infiltration rates are typically calculated by assuming that water flows as sheet flow over the slope. However, for most intensities water flow occurs in narrow and shallow micro-channels and concentrates in depressions. This channelization reduces the fraction of the soil surface covered with the water coming from the road. The non-uniform distribution of water along a hillslope directly affects infiltration. First, laboratory and field experiments have been conducted to characterize the spatial pattern of flow for stormwater runoff entering onto the surface of a sloped surface in a drainage ditch. In the laboratory experiments different micro-topographies were tested over bare sandy loam soil: a smooth surface, and three and five parallel rills. All the surfaces experienced erosion; the initially smooth surface developed a system of channels over time that increased runoff generation. On average, the initially smooth surfaces infiltrated 10% more volume than the initially rilled surfaces. The field experiments were performed in the side slope of established roadside drainage ditches. Three rates of runoff from a road surface into the swale slope were tested, representing runoff from 1, 2, and 10-year storm events. The average percentage of input runoff water infiltrated in the 32 experiments was 67%, with a 21% standard deviation. Multiple measurements of saturated hydraulic conductivity were conducted to account for its spatial variability. Second, a rate-based coupled infiltration and overland model has been designed that calculates stormwater infiltration efficiency of swales. The Green-Ampt-Mein-Larson assumptions were implemented to calculate infiltration along with a kinematic wave model for overland flow that accounts for short-circuiting of flow. Additionally, a sensitivity analysis on the parameters implemented in the model has been performed. Finally, the field experiments results have been used to quantify the validity of the coupled model.

Threshold and resilience management of coupled urbanization and water environmental system in the rapidly changing coastal region.

PubMed

Li, Yangfan; Li, Yi; Wu, Wei

2016-01-01

The concept of thresholds shows important implications for environmental and resource management. Here we derived potential landscape thresholds which indicated abrupt changes in water quality or the dividing points between exceeding and failing to meet national surface water quality standards for a rapidly urbanizing city on the Eastern Coast in China. The analysis of landscape thresholds was based on regression models linking each of the seven water quality variables to each of the six landscape metrics for this coupled land-water system. We found substantial and accelerating urban sprawl at the suburban areas between 2000 and 2008, and detected significant nonlinear relations between water quality and landscape pattern. This research demonstrated that a simple modeling technique could provide insights on environmental thresholds to support more-informed decision making in land use, water environmental and resilience management. Copyright © 2015 Elsevier Ltd. All rights reserved.

Understanding the biological underpinnings of ecohydrological processes

NASA Astrophysics Data System (ADS)

Huxman, T. E.; Scott, R. L.; Barron-Gafford, G. A.; Hamerlynck, E. P.; Jenerette, D.; Tissue, D. T.; Breshears, D. D.; Saleska, S. R.

2012-12-01

Climate change presents a challenge for predicting ecosystem response, as multiple factors drive both the physical and life processes happening on the land surface and their interactions result in a complex, evolving coupled system. For example, changes in surface temperature and precipitation influence near-surface hydrology through impacts on system energy balance, affecting a range of physical processes. These changes in the salient features of the environment affect biological processes and elicit responses along the hierarchy of life (biochemistry to community composition). Many of these structural or process changes can alter patterns of soil water-use and influence land surface characteristics that affect local climate. Of the many features that affect our ability to predict the future dynamics of ecosystems, it is this hierarchical response of life that creates substantial complexity. Advances in the ability to predict or understand aspects of demography help describe thresholds in coupled ecohydrological system. Disentangling the physical and biological features that underlie land surface dynamics following disturbance are allowing a better understanding of the partitioning of water in the time-course of recovery. Better predicting the timing of phenology and key seasonal events allow for a more accurate description of the full functional response of the land surface to climate. In addition, explicitly considering the hierarchical structural features of life are helping to describe complex time-dependent behavior in ecosystems. However, despite this progress, we have yet to build an ability to fully account for the generalization of the main features of living systems into models that can describe ecohydrological processes, especially acclimation, assembly and adaptation. This is unfortunate, given that many key ecosystem services are functions of these coupled co-evolutionary processes. To date, both the lack of controlled measurements and experimentation has precluded determination of sufficient theoretical development. Understanding the land-surface response and feedback to climate change requires a mechanistic understanding of the coupling of ecological and hydrological processes and an expansion of theory from the life sciences to appropriately contribute to the broader Earth system science goal.

An Open Source Framework for Coupled Hydro-Hydrogeo-Chemical Systems in Catchment Research

NASA Astrophysics Data System (ADS)

Delfs, J.; Sachse, A.; Gayler, S.; Grathwohl, P.; He, W.; Jang, E.; Kalbacher, T.; Klein, C.; Kolditz, O.; Maier, U.; Priesack, E.; Rink, K.; Selle, B.; Shao, H.; Singh, A. K.; Streck, T.; Sun, Y.; Wang, W.; Walther, M.

2013-12-01

This poster presents an open-source framework designed to assist water scientists in the study of catchment hydraulic functions with associated chemical processes, e.g. contaminant degradation, plant nutrient turnover. The model successfully calculates the feedbacks between surface water, subsurface water and air in standard benchmarks. In specific model applications to heterogeneous catchments, subsurface water is driven by density variations and runs through double porous media. Software codes of water science are tightly coupled by iteration, namely the Storm Water Management Model (SWMM) for urban runoff, Expert-N for simulating water fluxes and nutrient turnover in agricultural and forested soils, and OpenGeoSys (OGS) for groundwater. The coupled model calculates flow of hydrostatic shallow water over the land surface with finite volume and difference methods. The flow equations for water in the porous subsurface are discretized in space with finite elements. Chemical components are transferred through 1D, 2D or 3D watershed representations with advection-dispersion solvers or, as an alternative, random walk particle tracking. A transport solver can be in sequence with a chemical solver, e.g. PHREEQ-C, BRNS, additionally. Besides coupled partial differential equations, the concept of hydrological response units is employed in simulations at regional scale with scarce data availability. In this case, a conceptual hydrological model, specifically the Jena Adaptable Modeling System (JAMS), passes groundwater recharge through a software interface into OGS, which solves the partial differential equations of groundwater flow. Most components of the modeling framework are open source and can be modified for individual purposes. Applications range from temperate climate regions in Germany (Ammer catchment and Hessian Ried) to arid regions in the Middle East (Oman and Dead See). Some of the presented examples originate from intensively monitored research sites of the WESS research centre and the monitoring initiative TERENO. Other examples originate from the IWAS project on integrated water resources management. The model applications are primarily concerned with groundwater resources, which are endangered by overexploitation, intrusion of saltwater, and nitrate loads.

Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model

NASA Astrophysics Data System (ADS)

Alari, Victor; Staneva, Joanna; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian; Janssen, Peter

2016-08-01

Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on water temperature distribution and heat exchange at regional scale (the Baltic Sea). Four scenarios—including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination these forcings—were simulated to test the impact of different terms on simulated temperature distribution. The scenario simulations were compared to a control simulation, which included a constant wave-breaking coefficient, but otherwise was without any wave effects. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwelling's. Overall, when all three wave effects were accounted for, did the estimates of temperature improve compared to control simulation. During the summer, the wave-induced water temperature changes were up to 1 °C. In northern parts of the Baltic Sea, a warming of the surface layer occurs in the wave included simulations in summer months. This in turn reduces the cold bias between simulated and measured data, e.g. the control simulation was too cold compared to measurements. The warming is related to sea-state dependent energy flux. This implies that a spatio-temporally varying wave-breaking coefficient is necessary, because it depends on actual sea state. Wave-induced cooling is mostly observed in near-coastal areas and is the result of intensified upwelling in the scenario, when Stokes-Coriolis forcing is accounted for. Accounting for sea-state dependent momentum flux results in modified heat exchange at the water-air boundary which consequently leads to warming of surface water compared to control simulation.

Whole Planet Coupling from Climate to Core: Implications for the Evolution of Rocky Planets and their Prospects for Habitability

NASA Astrophysics Data System (ADS)

Foley, B. J.; Driscoll, P. E.

2015-12-01

Many factors have conspired to make Earth a home to complex life. Earth has abundant water due to a combination of factors, including orbital distance and the climate regulating feedbacks of the long-term carbon cycle. Earth has plate tectonics, which is crucial for maintaining long-term carbon cycling and may have been an important energy source for the origin of life in seafloor hydrothermal systems. Earth also has a strong magnetic field that shields the atmosphere from the solar wind and the surface from high-energy particles. Synthesizing recent work on these topics shows that water, a temperate climate, plate tectonics, and a strong magnetic field are linked together through a series of negative feedbacks that stabilize the system over geologic timescales. Although the physical mechanism behind plate tectonics on Earth is still poorly understood, climate is thought to be important. In particular, temperate surface temperatures are likely necessary for plate tectonics because they allow for liquid water that may be capable of significantly lowering lithospheric strength, increase convective stresses in the lithosphere, and enhance the effectiveness of "damage" processes such as grainsize reduction. Likewise, plate tectonics is probably crucial for maintaining a temperate climate on Earth through its role in facilitating the long-term carbon cycle, which regulates atmospheric CO2 levels. Therefore, the coupling between plate tectonics and climate is a feedback that is likely of first order importance for the evolution of rocky planets. Finally, plate tectonics is thought to be important for driving the geodynamo. Plate tectonics efficiently cools the mantle, leading to vigorous thermo-chemical convection in the outer core and dynamo action; without plate tectonics inefficient mantle cooling beneath a stagnant lid may prevent a long-lived magnetic field. As the magnetic field shields a planet's atmosphere from the solar wind, the magnetic field may be important for preserving hydrogen, and therefore water, on the surface. Thus whole planet coupling between the magnetic field, atmosphere, mantle, and core is possible. We lay out the basic physics governing whole planet coupling, and discuss the implications this coupling has for the evolution of rocky planets and their prospects for hosting life.

Sound radiation from a water-filled pipe, radiation into light fluid.

PubMed

Liu, Bilong; Pan, Jie; Li, Xiaodong; Tian, Jing

2002-12-01

This paper is concerned with the sound radiation from a water-filled exhaust pipe. The pipe opening and a plate attached to it form a vibrating surface for this radiation. Fluid-structural coupling between the pipe and enclosed fluid is included in the system modeling, but light fluid assumption is used for sound radiation into the space above the vibrating surface. In this paper, a numerical study on the n = 0 mode in the pipe shows that the wave types associated with this mode have different characteristics in two regions of the nondimensional frequency omega. In the first region of 0

Measurement and computation of hydrodynamic coupling at an air/water interface with an insoluble monolayer

NASA Astrophysics Data System (ADS)

Hirsa, Amir H.; Lopez, Juan M.; Miraghaie, Reza

2001-09-01

The coupling between a bulk vortical flow and a surfactant-influenced air/water interface has been examined in a canonical flow geometry through experiments and computations. The flow in an annular region bounded by stationary inner and outer cylinders is driven by the constant rotation of the floor and the free surface is initially covered by a uniformly distributed insoluble monolayer. When driven slowly, this geometry is referred to as the deep-channel surface viscometer and the flow is essentially azimuthal. The only interfacial property that affects the flow in this regime is the surface shear viscosity, [mu]s, which is uniform on the surface due to the vanishingly small concentration gradient. However, when operated at higher Reynolds number, secondary flow drives the surfactant film towards the inner cylinder until the Marangoni stress balances the shear stress on the bulk fluid. In general, the flow can be influenced by the surface tension, [sigma], and the surface dilatational viscosity, [kappa]s, as well as [mu]s. However, because of the small capillary number of the present flow, the effects of surface tension gradients dominate the surface viscosities in the radial stress balance, and the effect of [mu]s can only come through the azimuthal stress. Vitamin K1 was chosen for this study since it forms a well-behaved insoluble monolayer on water and [mu]s is essentially zero in the range of concentration on the surface, c, encountered. Thus the effect of Marangoni elasticity on the interfacial stress could be isolated. The flow near the interface was measured in an optical channel using digital particle image velocimetry. Steady axisymmetric flow was observed at the nominal Reynolds number of 8500. A numerical model has been developed using the axisymmetric Navier Stokes equations to examine the details of the coupling between the bulk and the interface. The nonlinear equation of state, [sigma](c), for the vitamin K1 monolayer was measured and utilized in the computations. Agreement was demonstrated between the measurements and computations, but the flow is critically dependent on the nonlinear equation of state.

Subsurface flow pathway dynamics in the active layer of coupled permafrost-hydrogeological systems under seasonal and annual temperature variability.

NASA Astrophysics Data System (ADS)

Frampton, Andrew

2017-04-01

There is a need for improved understanding of the mechanisms controlling subsurface solute transport in the active layer in order to better understand permafrost-hydrological-carbon feedbacks, in particular with regards to how dissolved carbon is transported in coupled surface and subsurface terrestrial arctic water systems under climate change. Studying solute transport in arctic systems is also relevant in the context of anthropogenic pollution which may increase due to increased activity in cold region environments. In this contribution subsurface solute transport subject to ground surface warming causing permafrost thaw and active layer change is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in subsurface water flows and solute transport travel times are analysed for different modelled geological configurations during a 100-year warming period. Results show that for all simulated cases, the minimum and mean travel times increase non-linearly with warming irrespective of geological configuration and heterogeneity structure. The timing of the start of increase in travel time depends on heterogeneity structure, combined with the rate of permafrost degradation that also depends on material thermal and hydrogeological properties. These travel time changes are shown to depend on combined warming effects of increase in pathway length due to deepening of the active layer, reduced transport velocities due to a shift from horizontal saturated groundwater flow near the surface to vertical water percolation deeper into the subsurface, and pathway length increase and temporary immobilization caused by cryosuction-induced seasonal freeze cycles. The impact these change mechanisms have on solute and dissolved substance transport is further analysed by integrating pathway analysis with a Lagrangian approach, incorporating considerations for both dissolved organic and inorganic carbon releases. Further model development challenges are also highlighted and discussed, including coupling between subsurface and surface runoff, soil deformations, as well as site applications and larger system scales.

A physical model of ice sheet response to changes in subglacial hydrology

NASA Astrophysics Data System (ADS)

Andrews, L. C.; Catania, G. A.; Buttles, J. L.; Andrews, A.; Markowski, M.

2010-12-01

Using a physical ice sheet model, we investigate the degree to which motion is controlled by local loss of basal traction versus longitudinal coupling during diurnal, seasonal, and event-type water pulses. Our model can be used to reproduce the spatial pattern and magnitude of ice surface displacements and can aid in the interpretation of ground-based GPS measurements, as it eliminates many of the complicating factors influencing surface velocity measurements. This model consists of a 3 x 1.5 meter plastic box with a grid of holes on the bed used to inject water directly between the interface of the box and a silicone polymer. Water flow is visualized using a colored dye. The polymer response to perturbations in water flow is measured by tracking surface markers through a series of overhead images. We report on a suite of experiments that explore the relationship between water discharge, basal traction, and surface displacements and compare our results to ground-based GPS measurements from a transect in western Greenland.

Status of surface-water modeling in the U.S. Geological Survey

USGS Publications Warehouse

Jennings, Marshall E.; Yotsukura, Nobuhiro

1979-01-01

The U.S. Geological Survey is active in the development and use of models for the analysis of various types of surface-water problems. Types of problems for which models have been, or are being developed, include categories such as the following: (1)specialized hydraulics, (2)flow routing in streams, estuaries, lakes, and reservoirs, (3) sedimentation, (4) transport of physical, chemical, and biological constituents, (5) surface exchange of heat and mass, (6) coupled stream-aquifer flow systems, (7) physical hydrology for rainfall-runoff relations, stream-system simulations, channel geometry, and water quality, (8) statistical hydrology for synthetic streamflows, floods, droughts, storage, and water quality, (9) management and operation problems, and (10) miscellaneous hydrologic problems. Following a brief review of activities prior to 1970, the current status of surface-water modeling is given as being in a developmental, verification, operational, or continued improvement phase. A list of recently published selected references, provides useful details on the characteristics of models.

Determination of Protein Surface Hydration by Systematic Charge Mutations

NASA Astrophysics Data System (ADS)

Yang, Jin; Jia, Menghui; Qin, Yangzhong; Wang, Dihao; Pan, Haifeng; Wang, Lijuan; Xu, Jianhua; Zhong, Dongping; Dongping Zhong Collaboration; Jianhua Xu Collaboration

Protein surface hydration is critical to its structural stability, flexibility, dynamics and function. Recent observations of surface solvation on picosecond time scales have evoked debate on the origin of such relatively slow motions, from hydration water or protein charged sidechains, especially with molecular dynamics simulations. Here, we used a unique nuclease with a single tryptophan as a local probe and systematically mutated neighboring three charged residues to differentiate the contributions from hydration water and charged sidechains. By mutations of alternative one and two and all three charged residues, we observed slight increases in the total tryptophan Stokes shifts with less neighboring charged residue(s) and found insensitivity of charged sidechains to the relaxation patterns. The dynamics is correlated with hydration water relaxation with the slowest time in a dense charged environment and the fastest time at a hydrophobic site. On such picosecond time scales, the protein surface motion is restricted. The total Stokes shifts are dominantly from hydration water relaxation and the slow dynamics is from water-driven relaxation, coupled with local protein fluctuations.

Semi-permeable surface analytical reversed-phase column for the improved trace analysis of acidic pesticides in water with coupled-column reversed-phase liquid chromatography with UV detection. Determination of bromoxynil and bentazone in surface water.

PubMed

Hogendoorn, E A; Westhuis, K; Dijkman, E; Heusinkveld, H A; den Boer, A C; Evers, E A; Baumann, R A

1999-10-08

The coupled-column (LC-LC) configuration consisting of a 3 microm C18 column (50 x 4.6 mm I.D.) as the first column and a 5 microm C18 semi-permeable-surface (SPS) column (150 x 4.6 mm I.D.) as the second column appeared to be successful for the screening of acidic pesticides in surface water samples. In comparison to LC-LC employing two C18 columns, the combination of C18/SPS-C18 significantly decreased the baseline deviation caused by the hump of the co-extracted humic substances when using UV detection (217 nm). The developed LC-LC procedure allowed the simultaneous determination of the target analytes bentazone and bromoxynil in uncleaned extracts of surface water samples to a level of 0.05 microg/l in less than 15 min. In combination with a simple solid-phase extraction step (200 ml of water on a 500 mg C18-bonded silica) the analytical procedure provides a high sample throughput. During a period of about five months more than 200 ditch-water samples originating from agricultural locations were analyzed with the developed procedure. Validation of the method was performed by randomly analyzing recoveries of water samples spiked at levels of 0.1 microg/l (n=10), 0.5 microg/l (n=7) and 2.5 microg/l (n=4). Weighted regression of the recovery data showed that the method provides overall recoveries of 95 and 100% for bentazone and bromoxynil, respectively, with corresponding intra-laboratory reproducibilities of 10 and 11%, respectively. Confirmation of the analytes in part of the samples extracts was carried out with GC-negative ion chemical ionization MS involving a derivatization step with bis(trifluoromethyl)benzyl bromide. No false negatives or positives were observed.

Effects of Surface Treatments on Mechanical Properties and Water Resistance of Kenaf Fiber-Reinforced Unsaturated Polyester Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiaofeng; Qui, Renhui; Fifield, Leonard S.

2012-05-17

Effects of surface treatments on the strength and water resistance of kenaf fiber-reinforced unsaturated polyester (UPE) composites were investigated. A new coupling agent that consists of 1,6-diisocyanato-hexane (DIH) and 2-hydroxylethyl acrylate (HEA) was investigated for surface treatments of kenaf fibers. The surface treatments were found to significantly enhance the tensile strength, modulus of rupture, modulus of elasticity, and water resistance of the resulting kenaf UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed that DIH-HEA was covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed that chemical treatment of kenaf fibers with a combination of DIHmore » and HEA improved the interfacial adhesion between kenaf fibers and UPE resin in the DIHHEA-treated kenafUPE composites. The mechanisms by which the chemical treatment of kenaf fiber surfaces improved strength and water resistance of the resulting kenaf UPE composites were discussed.« less

Nonlinear Acoustics at the Air-Water Free Surface

NASA Astrophysics Data System (ADS)

Pree, Seth; Naranjo, Brian; Putterman, Seth

2016-11-01

According to linear acoustics, airborne sound incident on a water surface transmits only a tenth of a percent of its energy. This difficulty of transmitting energy across the water surface limits the feasibility of standoff ultrasound imaging. We propose to overcome this long standing problem by developing new methods of coupling into the medium at standoff. In particular, we believe that the acoustic nonlinearity of both the air and the medium may yield a range of effects in the vicinity of the surface permitting an efficient transmission of ultrasound from the air into the medium. The recent commercial availability of parametric speakers that deliver modulated 100kHz ultrasound at 135dB to nonlinearly generate music at 95dB provides an interesting platform with which to revisit the transmission of sound across acoustic impedance mismatches. We show results of experimental studies of the behavior of the air-water free surface when subjected to large amplitude acoustic pressures from the air. This work was supported by the ARO STIR program.

On the use of the partitioning approach to derive Environmental Quality Standards (EQS) for persistent organic pollutants (POPs) in sediments: a review of existing data.

PubMed

Dueri, Sibylle; Castro-Jiménez, Javier; Comenges, José-Manuel Zaldívar

2008-09-15

A review of experimental data has been performed to study the relationships between the concentration in water, pore water and sediments for different families of organic contaminants. The objective was to determine whether it is possible to set EQS for sediments from EQS defined for surface waters in the Daughter Directive of the European Parliament (COM (2006) 397). The analysis of experimental data showed that even though in some specific cases there is a coupling between water column and sediments, this coupling is rather the exception. Therefore it is not recommendable to use water column data to assess the chemical quality status of sediments and it is necessary to measure in both media. At the moment EQS have been defined for the water column and will assess only the compliance with good chemical status of surface waters. Since the sediment toxicity depends on the dissolved pore water concentration, the EQS developed for water could be applied to pore water (interstitial water); hence, there would be no need of developing another set of EQS. The partitioning approach has been proposed as a solution to calculate sediment EQS from water EQS, but the partitioning coefficient strongly depends on sediment characteristics and its use introduces an important uncertainty in the definition of sediment EQS. Therefore, the direct measurement of pore water concentration is regarded as a better option.

Coupled SWAT-MODFLOW Model Development for Large Basins

NASA Astrophysics Data System (ADS)

Aliyari, F.; Bailey, R. T.; Tasdighi, A.

2017-12-01

Water management in semi-arid river basins requires allocating water resources between urban, industrial, energy, and agricultural sectors, with the latter competing for necessary irrigation water to sustain crop yield. Competition between these sectors will intensify due to changes in climate and population growth. In this study, the recently developed SWAT-MODFLOW coupled hydrologic model is modified for application in a large managed river basin that provides both surface water and groundwater resources for urban and agricultural areas. Specific modifications include the linkage of groundwater pumping and irrigation practices and code changes to allow for the large number of SWAT hydrologic response units (HRU) required for a large river basin. The model is applied to the South Platte River Basin (SPRB), a 56,980 km2 basin in northeastern Colorado dominated by large urban areas along the front range of the Rocky Mountains and agriculture regions to the east. Irregular seasonal and annual precipitation and 150 years of urban and agricultural water management history in the basin provide an ideal test case for the SWAT-MODFLOW model. SWAT handles land surface and soil zone processes whereas MODFLOW handles groundwater flow and all sources and sinks (pumping, injection, bedrock inflow, canal seepage, recharge areas, groundwater/surface water interaction), with recharge and stream stage provided by SWAT. The model is tested against groundwater levels, deep percolation estimates, and stream discharge. The model will be used to quantify spatial groundwater vulnerability in the basin under scenarios of climate change and population growth.

Evaluation of an operational water cycle prediction system for the Laurentian Great Lakes and St. Lawrence River

NASA Astrophysics Data System (ADS)

Fortin, Vincent; Durnford, Dorothy; Smith, Gregory; Dyck, Sarah; Martinez, Yosvany; Mackay, Murray; Winter, Barbara

2017-04-01

Environment and Climate Change Canada (ECCC) is implementing new numerical guidance products based on fully coupled numerical models to better inform the public as well as specialized users on the current and future state of various components of the water cycle, including stream flow and water levels. Outputs from this new system, named the Water Cycle Prediction System (WCPS), have been available for the Great Lakes and St. Lawrence River watershed since June 2016. WCPS links together ECCC's weather forecasting model, GEM, the 2-D ice model C-ICE, the 3-D lake and ocean model NEMO, and a 2-D hydrological model, WATROUTE. Information concerning the water cycle is passed between the models at intervals varying from a few minutes to one hour. It currently produces two forecasts per day for the next three days of the complete water cycle in the Great Lakes region, the largest freshwater lake system in the world. Products include spatially-varying precipitation, evaporation, river discharge, water level anomalies, surface water temperatures, ice coverage, and surface currents. These new products are of interest to water resources and management authority, flood forecasters, hydroelectricity producers, navigation, environmental disaster managers, search and rescue teams, agriculture, and the general public. This presentation focuses on the evaluation of various elements forecasted by the system, and weighs the advantages and disadvantages of running the system fully coupled.

Acidification at the Surface in the East Sea: A Coupled Climate-carbon Cycle Model Study

NASA Astrophysics Data System (ADS)

Park, Young-Gyu; Seol, Kyung-Hee; Boo, Kyung-On; Lee, Johan; Cho, Chunho; Byun, Young-Hwa; Seo, Seongbong

2018-05-01

This modeling study investigates the impacts of increasing atmospheric CO2 concentration on acidification in the East Sea. A historical simulation for the past three decades (1980 to 2010) was performed using the Hadley Centre Global Environmental Model (version 2), a coupled climate model with atmospheric, terrestrial and ocean cycles. As the atmospheric CO2 concentration increased, acidification progressed in the surface waters of the marginal sea. The acidification was similar in magnitude to observations and models of acidification in the global ocean. However, in the global ocean, the acidification appears to be due to increased in-situ oceanic CO2 uptake, whereas local processes had stronger effects in the East Sea. pH was lowered by surface warming and by the influx of water with higher dissolved inorganic carbon (DIC) from the northwestern Pacific. Due to the enhanced advection of DIC, the partial pressure of CO2 increased faster than in the overlying air; consequently, the in-situ oceanic uptake of CO2 decreased.

Open ocean pelago-benthic coupling: cyanobacteria as tracers of sedimenting salp faeces

NASA Astrophysics Data System (ADS)

Pfannkuche, Olaf; Lochte, Karin

1993-04-01

Coupling between surface water plankton and abyssal benthos was investigated during a mass development of salps ( Salpa fusiformis) in the Northeast Atlantic. Cyanobacteria numbers and composition of photosynthetic pigments were determined in faeces of captured salps from surface waters, sediment trap material, detritus from plankton hauls, surface sediments from 4500-4800 m depth and Holothurian gut contents. Cyanobacteria were found in all samples containing salp faeces and also in the guts of deep-sea Holothuria. The ratio between zeaxanthin (typical of cyanobacteria) and sum of chlorophyll a pigments was higher in samples from the deep sea when compared to fresh salp faeces, indicating that this carotenoid persisted longer in the sedimenting material than total chlorophyll a pigments. The microscopic and chemical observations allowed us to trace sedimenting salp faeces from the epipelagial to the abyssal benthos, and demonstrated their role as a fast and direct link between both systems. Cyanobacteria may provide a simple tracer for sedimenting phytodetritus.

An energy balance model exploration of the impacts of interactions between surface albedo, cloud cover and water vapor on polar amplification

NASA Astrophysics Data System (ADS)

Södergren, A. Helena; McDonald, Adrian J.; Bodeker, Gregory E.

2017-11-01

We examine the effects of non-linear interactions between surface albedo, water vapor and cloud cover (referred to as climate variables) on amplified warming of the polar regions, using a new energy balance model. Our simulations show that the sum of the contributions to surface temperature changes due to any variable considered in isolation is smaller than the temperature changes from coupled feedback simulations. This non-linearity is strongest when all three climate variables are allowed to interact. Surface albedo appears to be the strongest driver of this non-linear behavior, followed by water vapor and clouds. This is because increases in longwave radiation absorbed by the surface, related to increases in water vapor and clouds, and increases in surface absorbed shortwave radiation caused by a decrease in surface albedo, amplify each other. Furthermore, our results corroborate previous findings that while increases in cloud cover and water vapor, along with the greenhouse effect itself, warm the polar regions, water vapor also significantly warms equatorial regions, which reduces polar amplification. Changes in surface albedo drive large changes in absorption of incoming shortwave radiation, thereby enhancing surface warming. Unlike high latitudes, surface albedo change at low latitudes are more constrained. Interactions between surface albedo, water vapor and clouds drive larger increases in temperatures in the polar regions compared to low latitudes. This is in spite of the fact that, due to a forcing, cloud cover increases at high latitudes and decreases in low latitudes, and that water vapor significantly enhances warming at low latitudes.

The intraannual variability of land-atmosphere coupling over North America in the Canadian Regional Climate Model (CRCM5)

NASA Astrophysics Data System (ADS)

Yang Kam Wing, G.; Sushama, L.; Diro, G. T.

2016-12-01

This study investigates the intraannual variability of soil moisture-temperature coupling over North America. To this effect, coupled and uncoupled simulations are performed with the fifth-generation Canadian Regional Climate Model (CRCM5), driven by ERA-Interim. In coupled simulations, land and atmosphere interact freely; in uncoupled simulations, the interannual variability of soil moisture is suppressed by prescribing climatological values for soil liquid and frozen water contents. The study also explores projected changes to coupling by comparing coupled and uncoupled CRCM5 simulations for current (1981-2010) and future (2071-2100) periods, driven by the Canadian Earth System Model. Coupling differs for the northern and southern parts of North America. Over the southern half, it is persistent throughout the year while for the northern half, strongly coupled regions generally follow the freezing line during the cold months. Detailed analysis of the southern Canadian Prairies reveals seasonal differences in the underlying coupling mechanism. During spring and fall, as opposed to summer, the interactive soil moisture phase impacts the snow depth and surface albedo, which further impacts the surface energy budget and thus the surface air temperature; the air temperature then influences the snow depth in a feedback loop. Projected changes to coupling are also season specific: relatively drier soil conditions strengthen coupling during summer, while changes in soil moisture phase, snow depth, and cloud cover impact coupling during colder months. Furthermore, results demonstrate that soil moisture variability amplifies the frequency of temperature extremes over regions of strong coupling in current and future climates.

A multicomponent coupled model of glacier hydrology 1. Theory and synthetic examples

NASA Astrophysics Data System (ADS)

Flowers, Gwenn E.; Clarke, Garry K. C.

2002-11-01

Basal hydrology is acknowledged as a fundamental control on glacier dynamics, especially in cases where surface meltwater reaches the bed. For many glaciers at midlatitudes, basal drainage is influenced by subaerial, englacial, and subsurface water flow. One of the major shortcomings of existing basal hydrology models is the treatment of the glacier bed as an isolated system. We present theoretical and computational models that couple glacier surface runoff, englacial water storage and transport, subglacial drainage, and subsurface groundwater flow. Each of the four model components is represented as a two-dimensional, vertically integrated layer that communicates with its neighbors through water exchange. Governing equations are derived from the law of mass conservation and are expressed as a balance between the internal distribution of water and external sources. The numerical exposition of this theory is a time-dependent finite difference model that can be used to simulate glacier drainage. In this paper we outline the theory and conduct simple tests using an idealized glacier geometry. In the companion paper, the model is tailored to Trapridge Glacier, Yukon Territory, Canada, where results are compared with measurements of subglacial water pressure.

Using a hybrid model to predict solute transfer from initially saturated soil into surface runoff with controlled drainage water.

PubMed

Tong, Juxiu; Hu, Bill X; Yang, Jinzhong; Zhu, Yan

2016-06-01

The mixing layer theory is not suitable for predicting solute transfer from initially saturated soil to surface runoff water under controlled drainage conditions. By coupling the mixing layer theory model with the numerical model Hydrus-1D, a hybrid solute transfer model has been proposed to predict soil solute transfer from an initially saturated soil into surface water, under controlled drainage water conditions. The model can also consider the increasing ponding water conditions on soil surface before surface runoff. The data of solute concentration in surface runoff and drainage water from a sand experiment is used as the reference experiment. The parameters for the water flow and solute transfer model and mixing layer depth under controlled drainage water condition are identified. Based on these identified parameters, the model is applied to another initially saturated sand experiment with constant and time-increasing mixing layer depth after surface runoff, under the controlled drainage water condition with lower drainage height at the bottom. The simulation results agree well with the observed data. Study results suggest that the hybrid model can accurately simulate the solute transfer from initially saturated soil into surface runoff under controlled drainage water condition. And it has been found that the prediction with increasing mixing layer depth is better than that with the constant one in the experiment with lower drainage condition. Since lower drainage condition and deeper ponded water depth result in later runoff start time, more solute sources in the mixing layer are needed for the surface water, and larger change rate results in the increasing mixing layer depth.

Incorporation of ice sheet models into an Earth system model: Focus on methodology of coupling

NASA Astrophysics Data System (ADS)

Rybak, Oleg; Volodin, Evgeny; Morozova, Polina; Nevecherja, Artiom

2018-03-01

Elaboration of a modern Earth system model (ESM) requires incorporation of ice sheet dynamics. Coupling of an ice sheet model (ICM) to an AOGCM is complicated by essential differences in spatial and temporal scales of cryospheric, atmospheric and oceanic components. To overcome this difficulty, we apply two different approaches for the incorporation of ice sheets into an ESM. Coupling of the Antarctic ice sheet model (AISM) to the AOGCM is accomplished via using procedures of resampling, interpolation and assigning to the AISM grid points annually averaged meanings of air surface temperature and precipitation fields generated by the AOGCM. Surface melting, which takes place mainly on the margins of the Antarctic peninsula and on ice shelves fringing the continent, is currently ignored. AISM returns anomalies of surface topography back to the AOGCM. To couple the Greenland ice sheet model (GrISM) to the AOGCM, we use a simple buffer energy- and water-balance model (EWBM-G) to account for orographically-driven precipitation and other sub-grid AOGCM-generated quantities. The output of the EWBM-G consists of surface mass balance and air surface temperature to force the GrISM, and freshwater run-off to force thermohaline circulation in the oceanic block of the AOGCM. Because of a rather complex coupling procedure of GrIS compared to AIS, the paper mostly focuses on Greenland.

Coupling Meteorological, Land Surface and Water Temperature Models in the Mississippi River Basin

NASA Astrophysics Data System (ADS)

Tang, C.; Cooter, E. J.

2017-12-01

Water temperature is a significant factor influencing of the stream ecosystem and water management especially under climate change. In this study, we demonstrate a physically based semi-Lagrangian water temperature model (RBM) coupled with the Variable Infiltration Capacity (VIC) hydrology model and Weather Research & Forecasting Model (WRF) in the Mississippi River Basin (MRB). The results of this coupling compare favorably with observed water temperature data at river gages throughout the MRB. Further sensitivity analysis shows that mean water temperatures increase by 1.3°C, 1.5°C, and 1.8°C in northern, central and southern MRB zones, respectively, under a hypothetical uniform air temperature increase of 3°C. If air temperatures increase uniformly by 6°C in this scenario, then water temperatures are projected to increase by 3.3°C, 3.5°C and 4.0°C. Lastly, downscaled air temperatures from a global climate model are used to drive the coupled VIC and RBM model from 2020 to 2099. Average stream temperatures from 2020 to 2099 increase by 1°C to 8°C above 1950 to 2010 average water temperatures, with non-uniform increases along the river. In some portions of the MRB, stream temperatures could increase above survival thresholds for several native fish species, which are critical components of the stream ecosystem. The increased water temperature accelerates harmful algal blooming which results in a larger dead zone in the Gulf of Mexico.

Using an implicitly-coupled hydrologic and river-operations models to investigate the trade-offs of artificial recharge in agricultural areas

NASA Astrophysics Data System (ADS)

Morway, E. D.; Niswonger, R. G.; Triana, E.

2016-12-01

In irrigated agricultural regions supplied by both surface-water and groundwater, increased reliance on groundwater during sustained drought leads to long-term water table drawdown and subsequent surface-water losses. This, in turn, may threaten the sustainability of the irrigation project. To help offset groundwater resource losses and restore water supply reliability, an alternative management strategy commonly referred to as managed aquifer recharge (MAR) in agricultural regions helps mitigate long-term aquifer drawdown and provides additional water for subsequent withdraw. Sources of MAR in this investigation are limited to late winter runoff in years with above average precipitation (i.e., above average snowpack). However, where winter MAR results in an elevated water table, non-beneficial consumptive use may increase from evapotranspiration in adjacent and down-gradient fallow and naturally vegetated lands. To rigorously explore this trade-off, the recently published MODSIM-MODFLOW model was applied to quantify both the benefits and unintended consequences of MAR. MODSIM-MODFLOW is a generalized modeling tool capable of exploring the effects of altered river operations within an integrated groundwater and surface-water (GW-SW) model. Thus, the MODSIM-MODFLOW model provides a modeling platform capable of simulating MAR in amounts and duration consistent with other senior water rights in the river system (e.g., minimum in-stream flow requirements). Increases in non-beneficial consumptive use resulting from winter MAR are evaluated for a hypothetical model patterned after alluvial aquifers common in arid and semi-arid areas of the western United States. Study results highlight (1) the benefit of an implicitly-coupled river operations and hydrologic modeling tool, (2) the balance between winter MAR and the potential increase in non-beneficial consumptive use, and (3) conditions where MAR may or may not be an appropriate management option, such as the availability of surface-water storage.

Dynamical Coupling of Intrinsically Disordered Proteins and Their Hydration Water: Comparison with Folded Soluble and Membrane Proteins

PubMed Central

Gallat, F.-X.; Laganowsky, A.; Wood, K.; Gabel, F.; van Eijck, L.; Wuttke, J.; Moulin, M.; Härtlein, M.; Eisenberg, D.; Colletier, J.-P.; Zaccai, G.; Weik, M.

2012-01-01

Hydration water is vital for various macromolecular biological activities, such as specific ligand recognition, enzyme activity, response to receptor binding, and energy transduction. Without hydration water, proteins would not fold correctly and would lack the conformational flexibility that animates their three-dimensional structures. Motions in globular, soluble proteins are thought to be governed to a certain extent by hydration-water dynamics, yet it is not known whether this relationship holds true for other protein classes in general and whether, in turn, the structural nature of a protein also influences water motions. Here, we provide insight into the coupling between hydration-water dynamics and atomic motions in intrinsically disordered proteins (IDP), a largely unexplored class of proteins that, in contrast to folded proteins, lack a well-defined three-dimensional structure. We investigated the human IDP tau, which is involved in the pathogenic processes accompanying Alzheimer disease. Combining neutron scattering and protein perdeuteration, we found similar atomic mean-square displacements over a large temperature range for the tau protein and its hydration water, indicating intimate coupling between them. This is in contrast to the behavior of folded proteins of similar molecular weight, such as the globular, soluble maltose-binding protein and the membrane protein bacteriorhodopsin, which display moderate to weak coupling, respectively. The extracted mean square displacements also reveal a greater motional flexibility of IDP compared with globular, folded proteins and more restricted water motions on the IDP surface. The results provide evidence that protein and hydration-water motions mutually affect and shape each other, and that there is a gradient of coupling across different protein classes that may play a functional role in macromolecular activity in a cellular context. PMID:22828339

Assessing the Influence of Human Activities on Global Water Resources Using an Advanced Land Surface Model

NASA Astrophysics Data System (ADS)

Pokhrel, Y.; Hanasaki, N.; Koirala, S.; Kanae, S.; Oki, T.

2010-12-01

In order to examine the impact of human intervention on the global hydrological cycle, a Land Surface Model was enhanced with schemes to assess the anthropogenic disturbance on the natural water flow at the global scale. Four different schemes namely; reservoir operation, crop growth, environmental flow, and anthropogenic water withdrawal modules from a state-of-the-art global water resources assessment model called H08 were integrated into an offline version of LSM, Minimal Advance Treatment of Surface Interaction and Runoff (MATSIRO). MATSIRO represents majority of the hydrological processes of water and energy exchange between the land surface and the atmosphere on a physical basis and is designed to be coupled with GCM. The integrated model presented here thus has the capability to simulate both natural and anthropogenic flows of water globally at a spatial resolution of 1°x1°, considering dam operation, domestic, industrial and agricultural water withdrawals and environmental flow requirements. The model can also be coupled with climate models to assess the impact of human activities on the climate system. A simple groundwater scheme was also incorporated and the model can be used to assess the change in water table due to groundwater pumping for irrigation. The model was validated by comparing simulated soil moisture, river discharge and Terrestrial Water Storage Anomaly (TWSA) with observations. The model performs well in simulating TWSA as compared to GRACE observation in different river basins ranging from very wet to very dry. Soil moisture cannot be validated globally because of the lack of validation datasets. For Illinois region, where long term soil moisture observations are available, the model captures the seasonal variation quite well. The simulated global potential irrigation demand is about 1100km3/year, which is within the range of previously published estimates based on various water balance models and LSMs. The model has an advanced option to limit water withdrawal from river channels based on water availability and environmental flow requirements. Results showed that about three-fourth of the irrigation demand can be met from surface-water (rivers, small and medium-sized reservoirs). Therefore, one-fourth of the demand must have been supplied by groundwater. Further analysis of modeled groundwater pumping for irrigation is needed to examine the extent of groundwater withdrawal and its impact on water table fluctuations.

The Implement of a Multi-layer Frozen Soil Scheme into SSiB3 and its Evaluation over Cold Regions

NASA Astrophysics Data System (ADS)

Li, Q.

2016-12-01

The SSiB3 is a biophysics-based model of land-atmosphere interactions and is designed for global and regional studies. It has three soil layers, three snow layers, as well as one vegetation layer. Soil moisture of the three soil layers, interception water store for the canopy, subsurface soil temperature, ground temperature, canopy temperature and snow water equivalent are all predicted based on the water and energy balance at canopy, soil and snow. SSiB3 substantially enhances the model's capability for cold season studies and produces reasonable results compared with observations. However, frozen soil processes are ignored in the SSiB3 and may have effects on the interannual variability of soil temperature and deep soil memory. A multi-layer comprehensive frozen soil scheme (FSM), which is developed for climate study has been implemented into the SSiB3 to describe soil heat transfer and water flow affected by frozen processed in soil. In the coupled SSiB3-FSM, both liquid water and ice content have been taken into account in the frozen soil hydrologic and thermal property parameterization. The maximum soil layer depth could reach 10 meters thick depending on land conditions. To better evaluate the models' performance, the coupled offline SSiB3-FSM and SSiB3 have been driven from 1948 to 1958 by the Princeton global meteorological data set, respectively. For the 10yrs run, the coupled SSiB3-FSM almost captures the features over different regions, especially cold regions. In order to analysis and compare the differences of SSIB3-FSM and SSIB3 in detail, monthly mean surface temperature for different regions are compared with CAMS data. The statistical results of surface skin temperature show that high latitude regions, Africa, Eastern Australia, and North American monsoon regions have been greatly improved in SSIB3-FSM. For the global statistics, the RMSE of the surface temperature simulated by SSiB3-FSM can be improved about 0.6K compared to SSiB3. In this study, the improvements in the coupled SSiB3-FSM have also been analyzed.

Effective use of surface-water management to control saltwater intrusion

NASA Astrophysics Data System (ADS)

Hughes, J. D.; White, J.

2012-12-01

The Biscayne aquifer in southeast Florida is susceptible to saltwater intrusion and inundation from rising sea-level as a result of high groundwater withdrawal rates and low topographic relief. Groundwater levels in the Biscayne aquifer are managed by an extensive canal system that is designed to control flooding, supply recharge to municipal well fields, and control saltwater intrusion. We present results from an integrated surface-water/groundwater model of a portion of the Biscayne aquifer to evaluate the ability of the existing managed surface-water control network to control saltwater intrusion. Surface-water stage and flow are simulated using a hydrodynamic model that solves the diffusive-wave approximation of the depth-integrated shallow surface-water equations. Variable-density groundwater flow and fluid density are solved using the Oberbeck--Boussinesq approximation of the three-dimensional variable-density groundwater flow equation and a sharp interface approximation, respectively. The surface-water and variable-density groundwater domains are implicitly coupled during each Picard iteration. The Biscayne aquifer is discretized into a multi-layer model having a 500-m square horizontal grid spacing. All primary and secondary surface-water features in the active model domain are discretized into segments using the 500-m square horizontal grid. A 15-year period of time is simulated and the model includes 66 operable surface-water control structures, 127 municipal production wells, and spatially-distributed daily internal and external hydrologic stresses. Numerical results indicate that the existing surface-water system can be effectively used in many locations to control saltwater intrusion in the Biscayne aquifer resulting from increases in groundwater withdrawals or sea-level rise expected to occur over the next 25 years. In other locations, numerical results indicate surface-water control structures and/or operations may need to be modified to control saltwater intrusion.

Improvements in lake water budget computations using Landsat data

NASA Technical Reports Server (NTRS)

Gervin, J. C.; Shih, S. F.

1979-01-01

A supervised multispectral classification was performed on Landsat data for Lake Okeechobee's extensive littoral zone to provide two types of information. First, the acreage of a given plant species as measured by satellite was combined with a more accurate transpiration rate to give a better estimate of evapotranspiration from the littoral zone. Second, the surface area coupled by plant communities was used to develop a better estimate of the water surface as a function of lake stage. Based on this information, more detailed representations of evapotranspiration and total water surface (and hence total lake volume) were provided to the water balance budget model for lake volume predictions. The model results based on information derived from satellite demonstrated a 94 percent reduction in cumulative lake stage error and a 70 percent reduction in the maximum deviation of the lake stage.

Isomerization reaction dynamics and equilibrium at the liquid-vapor interface of water. A molecular-dynamics study

NASA Technical Reports Server (NTRS)

Benjamin, Ilan; Pohorille, Andrew

1993-01-01

The gauche-trans isomerization reaction of 1,2-dichloroethane at the liquid-vapor interface of water is studied using molecular-dynamics computer simulations. The solvent bulk and surface effects on the torsional potential of mean force and on barrier recrossing dynamics are computed. The isomerization reaction involves a large change in the electric dipole moment, and as a result the trans/gauche ratio is considerably affected by the transition from the bulk solvent to the surface. Reactive flux correlation function calculations of the reaction rate reveal that deviation from the transition-state theory due to barrier recrossing is greater at the surface than in the bulk water. This suggests that the system exhibits non-Rice-Ramsperger-Kassel-Marcus behavior due to the weak solvent-solute coupling at the water liquid-vapor interface.

Plant leaves as natural green scaffolds for palladium catalyzed Suzuki-Miyaura coupling reactions.

PubMed

Sharma, Vipul; Kumar, Suneel; Bahuguna, Ashish; Gambhir, Diksha; Sagara, Prateep Singh; Krishnan, Venkata

2016-12-21

This work presents a novel approach of using natural plant leaf surfaces having intricate hierarchical structures as scaffolds for Pd nanoparticles and demonstrated it as a Green dip catalyst for Suzuki-Miyaura coupling reactions in water. The influence of the topographical texture of the plant leaves on the deposition and catalytic properties of Pd nanoparticles are presented and discussed. The catalytic activity can be correlated to the surface texture of the leaves, wherein it has been found that the micro/nanostructures present on the surface strongly influence the assembly and entrapment of the nanoparticles, and thereby control aggregation and leaching of the catalysts. This approach can provide insights for the future design and fabrication of bioinspired supports for catalysis, based on replication of leaf surfaces.

The Bidirectional Reflectance Distribution Function (BRDF) of the Ocean: Effects of Wave Representation

NASA Astrophysics Data System (ADS)

Eide, H.; Stamnes, K.; Ottaviani, M.

2004-12-01

The specular reflection of the Sun off the ocean, or sun glint, is of major concern for ocean remote sensing. Typically, data from in and around the sunglint region are discarded because of the unknown contribution to the measured radiances or because of sensor saturation. On the other hand, accurate knowledge of the sunglint properties enables retrievals of atmospheric parameters. The challenge of the ocean retrieval problem is to get the ``water leaving radiance'', Lw, by subtracting the Rayleigh scattering, aerosol scattering, water vapor, ozone, and sun glint from the measured radiances at the top of the atmosphere (TOA). Thus, the task is to correct for both the atmospheric contribution and for surface effects. Two simplifying assumptions that are frequently employed in ocean remote sensing are that the ocean BRDF is isotropic and that one can de-couple the radiative properties of the atmosphere from those of the surface. Our previous studies have shown that neglecting the inherit coupling between the atmosphere and surface can lead to large errors in the retrievals. In order to do retrievals over bright, as well as darker surfaces, it is necessary to account for this coupling between the surface and the atmosphere. In the present study we use models for the reflection of light off the ocean surface to calculate the ocean BRDF. The differences between the various models are investigated as is the effect of using different types of wave statistics (e.g. Cox Munk). We present results from calculations where we vary the wind speed and direction as well as other parameters affecting the ocean surface. The error introduced in ocean retrievals by assuming an isotropic BRDF is assessed, and methods for improved treatment of sunglint are suggested.

Diagnosing the Nature of Land-Atmosphere Coupling During the 2006-7 Dry/Wet Extremes in the U.S. Southern Great Plains

NASA Technical Reports Server (NTRS)

Santanello, Joseph A., Jr.; Peters-Lidard, Christa D.; Kumar, Sujay V.; Dong, Xiquan; Kennedy, Aaron D.

2011-01-01

Land-atmosphere interactions play a critical role in determining the. diurnal evolution of both planetary boundary layer (PBL) and land surface temperature and moisture states. The degree of coupling between the land surface and PBL in numerical weather prediction and climate models remains largely unexplored and undiagnosed due to the complex interactions and feedbacks present across a range of scales. Further, uncoupled systems or experiments (e.g., the Project for Intercomparison of Land Parameterization Schemes, PILPS) may lead to inaccurate water and energy cycle process understanding by neglecting feedback processes such as PBL-top entrainment. In this study, a framework for diagnosing local land-atmosphere coupling (LoCo) is presented using a coupled mesoscale model with a suite of PBL and land surface model (LSM) options along with observations during the summers of 200617 in the U.S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to NASA's Land Information System (LIS), which provides a flexible and high-resolution representation and initialization of land surface physics and states. A range of diagnostics exploring the links and feedbacks between soil moisture and precipitation are examined for the dry/wet extremes of this region, along with the sensitivity of PBL-LSM coupling to perturbations in soil moisture. As such, this methodology provides a potential pathway to study factors controlling local land-atmosphere coupling (LoCo) using the LIS-WRF system, which is serving as a testbed for LoCo experiments to evaluate coupling diagnostics within the community.

Modelling Soil Heat and Water Flow as a Coupled Process in Land Surface Models

NASA Astrophysics Data System (ADS)

García González, Raquel; Verhoef, Anne; Vidale, Pier Luigi; Braud, Isabelle

2010-05-01

To improve model estimates of soil water and heat flow by land surface models (LSMs), in particular in the first few centimetres of the near-surface soil profile, we have to consider in detail all the relevant physical processes involved (see e.g. Milly, 1982). Often, thermal and iso-thermal vapour fluxes in LSMs are neglected and the simplified Richard's equation is used as a result. Vapour transfer may affect the water fluxes and heat transfer in LSMs used for hydrometeorological and climate simulations. Processes occurring in the top 50 cm soil may be relevant for water and heat flux dynamics in the deeper layers, as well as for estimates of evapotranspiration and heterotrophic respiration, or even for climate and weather predictions. Water vapour transfer, which was not incorporated in previous versions of the MOSES/JULES model (Joint UK Land Environment Simulator; Cox et al., 1999), has now been implemented. Furthermore, we also assessed the effect of the soil vertical resolution on the simulated soil moisture and temperature profiles and the effect of the processes occurring at the upper boundary, mainly in terms of infiltration rates and evapotranspiration. SiSPAT (Simple Soil Plant Atmosphere Transfer Model; Braud et al., 1995) was initially used to quantify the changes that we expect to find when we introduce vapour transfer in JULES, involving parameters such as thermal vapour conductivity and diffusivity. Also, this approach allows us to compare JULES to a more complete and complex numerical model. Water vapour flux varied with soil texture, depth and soil moisture content, but overall our results suggested that water vapour fluxes change temperature gradients in the entire soil profile and introduce an overall surface cooling effect. Increasing the resolution smoothed and reduced temperature differences between liquid (L) and liquid/vapour (LV) simulations at all depths, and introduced a temperature increase over the entire soil profile. Thermal gradients rather than soil water potential gradients seem to cause temporal and spatial (vertical) soil temperature variability. We conclude that a multi-soil layer configuration may improve soil water dynamics, heat transfer and coupling of these processes, as well as evapotranspiration estimates and land surface-atmosphere coupling. However, a compromise should be reached between numerical and process-simulation aspects. References: Braud I., A.C. Dantas-Antonino, M. Vauclin, J.L. Thony and P. Ruelle, 1995b: A Simple Soil Plant Atmo- sphere Transfer model (SiSPAT), Development and field verification, J. Hydrol, 166: 213-250 Cox, P.M., R.A. Betts, C.B. Bunton, R.L.H. Essery, P.R. Rowntree, and J. Smith (1999), The impact of new land surface physics on the GCM simulation of climate and climate sensitivity. Clim. Dyn., 15, 183-203. Milly, P.C.D., 1982. Moisture and heat transport in hysteric inhomogeneous porous media: a matric head- based formulation and a numerical model, Water Resour. Res., 18:489-498

Role of Stratospheric Water Vapor in Global Warming from GCM Simulations Constrained by MLS Observation

NASA Astrophysics Data System (ADS)

Wang, Y.; Stek, P. C.; Su, H.; Jiang, J. H.; Livesey, N. J.; Santee, M. L.

2014-12-01

Over the past century, global average surface temperature has warmed by about 0.16°C/decade, largely due to anthropogenic increases in well-mixed greenhouse gases. However, the trend in global surface temperatures has been nearly flat since 2000, raising a question regarding the exploration of the drivers of climate change. Water vapor is a strong greenhouse gas in the atmosphere. Previous studies suggested that the sudden decrease of stratospheric water vapor (SWV) around 2000 may have contributed to the stall of global warming. Since 2004, the SWV observed by Microwave Limb Sounder (MLS) on Aura satellite has shown a slow recovery. The role of recent SWV variations in global warming has not been quantified. We employ a coupled atmosphere-ocean climate model, the NCAR CESM, to address this issue. It is found that the CESM underestimates the stratospheric water vapor by about 1 ppmv due to limited representations of the stratospheric dynamic and chemical processes important for water vapor variabilities. By nudging the modeled SWV to the MLS observation, we find that increasing SWV by 1 ppmv produces a robust surface warming about 0.2°C in global-mean when the model reaches equilibrium. Conversely, the sudden drop of SWV from 2000 to 2004 would cause a surface cooling about -0.08°C in global-mean. On the other hand, imposing the observed linear trend of SWV based on the 10-year observation of MLS in the CESM yields a rather slow surface warming, about 0.04°C/decade. Our model experiments suggest that SWV contributes positively to the global surface temperature variation, although it may not be the dominant factor that drives the recent global warming hiatus. Additional sensitivity experiments show that the impact of SWV on surface climate is mostly governed by the SWV amount at 100 hPa in the tropics. Furthermore, the atmospheric model simulations driven by observed sea surface temperature (SST) show that the inter-annual variation of SWV follows that of SST, suggesting a close coupling between surface temperature and SWV.

Mathematical model reveals role of nucleotide signaling in airway surface liquid homeostasis and its dysregulation in cystic fibrosis

PubMed Central

Sandefur, Conner I.; Boucher, Richard C.; Elston, Timothy C.

2017-01-01

Mucociliary clearance is composed of three components (i.e., mucin secretion, airway surface hydration, and ciliary-activity) which function coordinately to clear inhaled microbes and other foreign particles from airway surfaces. Airway surface hydration is maintained by water fluxes driven predominantly by active chloride and sodium ion transport. The ion channels that mediate electrogenic ion transport are regulated by extracellular purinergic signals that signal through G protein-coupled receptors. These purinoreceptors and the signaling pathways they activate have been identified as possible therapeutic targets for treating lung disease. A systems-level description of airway surface liquid (ASL) homeostasis could accelerate development of such therapies. Accordingly, we developed a mathematical model to describe the dynamic coupling of ion and water transport to extracellular purinergic signaling. We trained our model from steady-state and time-dependent experimental measurements made using normal and cystic fibrosis (CF) cultured human airway epithelium. To reproduce CF conditions, reduced chloride secretion, increased potassium secretion, and increased sodium absorption were required. The model accurately predicted ASL height under basal normal and CF conditions and the collapse of surface hydration due to the accelerated nucleotide metabolism associated with CF exacerbations. Finally, the model predicted a therapeutic strategy to deliver nucleotide receptor agonists to effectively rehydrate the ASL of CF airways. PMID:28808008

Time and space analysis of turbulence of gravity surface waves

NASA Astrophysics Data System (ADS)

Mordant, Nicolas; Aubourg, Quentin; Viboud, Samuel; Sommeria, Joel

2016-11-01

Wave turbulence is a statistical state made of a very large number of nonlinearly interacting waves. The Weak Turbulence Theory was developed to describe such a situation in the weakly nonlinear regime. Although, oceanic data tend to be compatible with the theory, laboratory data fail to fulfill the theoretical predictions. A space-time resolved measurement of the waves have proven to be especially fruitful to identify the mechanism at play in turbulence of gravity-capillary waves. We developed an image processing algorithm to measure the motion of the surface of water with both space and time resolution. We first seed the surface with slightly buoyant polystyrene particles and use 3 cameras to reconstruct the surface. Our stereoscopic algorithm is coupled to PIV so that to obtain both the surface deformation and the velocity of the water surface. Such a coupling is shown to improve the sensitivity of the measurement by one order of magnitude. We use this technique to probe the existence of weakly nonlinear turbulence excited by two small wedge wavemakers in a 13-m diameter wave flume. We observe a truly weakly nonlinear regime of isotropic wave turbulence. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No 647018-WATU).

Microbiologically Influenced Corrosion

DTIC Science & Technology

2009-01-01

related directly to the biomineralized deposits on the surface. Ennoble- ment in marine waters has been attributed to depolarization of the oxygen... abiotic ally oxi- dized metal precipitates, and still others that derive energy by oxidizing metals. Manganese. Manganese oxidation is coupled to cell...circumstances, pitting involves the conventional features of differential aeration, a large cathode: anode surface area, and the development of

Quantum calculations of the IR spectrum of liquid water using ab initio and model potential and dipole moment surfaces and comparison with experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Hanchao; Wang, Yimin; Bowman, Joel M.

2015-05-21

The calculation and characterization of the IR spectrum of liquid water have remained a challenge for theory. In this paper, we address this challenge using a combination of ab initio approaches, namely, a quantum treatment of IR spectrum using the ab initio WHBB water potential energy surface and a refined ab initio dipole moment surface. The quantum treatment is based on the embedded local monomer method, in which the three intramolecular modes of each embedded H{sub 2}O monomer are fully coupled and also coupled singly to each of six intermolecular modes. The new dipole moment surface consists of a previousmore » spectroscopically accurate 1-body dipole moment surface and a newly fitted ab initio intrinsic 2-body dipole moment. A detailed analysis of the new dipole moment surface in terms of the coordinate dependence of the effective atomic charges is done along with tests of it for the water dimer and prism hexamer double-harmonic spectra against direct ab initio calculations. The liquid configurations are taken from previous molecular dynamics calculations of Skinner and co-workers, using the TIP4P plus E3B rigid monomer water potential. The IR spectrum of water at 300 K in the range of 0–4000 cm{sup −1} is calculated and compared with experiment, using the ab initio WHBB potential and new ab initio dipole moment, the q-TIP4P/F potential, which has a fixed-charged description of the dipole moment, and the TTM3-F potential and dipole moment surfaces. The newly calculated ab initio spectrum is in very good agreement with experiment throughout the above spectral range, both in band positions and intensities. This contrasts to results with the other potentials and dipole moments, especially the fixed-charge q-TIP4P/F model, which gives unrealistic intensities. The calculated ab initio spectrum is analyzed by examining the contribution of various transitions to each band.« less

Design and Impacts of Land-Biogenic-Atmosphere Coupling in the NASA-Unified WRF (NU-WRF) Modeling System

NASA Technical Reports Server (NTRS)

Tan, Qian; Santanello, Joseph A., Jr.; Zhou, Shujia; Tao, Zhining; Peters-Lidard, Christa d.; Chn, Mian

2011-01-01

Land-Atmosphere coupling is typically designed and implemented independently for physical (e.g. water and energy) and chemical (e.g. biogenic emissions and surface depositions)-based models and applications. Differences in scale, data requirements, and physics thus limit the ability of Earth System models to be fully coupled in a consistent manner. In order for the physical-chemical-biological coupling to be complete, treatment of the land in terms of surface classification, condition, fluxes, and emissions must be considered simultaneously and coherently across all components. In this study, we investigate a coupling strategy for the NASA-Unified Weather Research and Forecasting (NU-WRF) model that incorporates the traditionally disparate fluxes of water and energy through NASA's LIS (Land Information System) and biogenic emissions through BEIS (Biogenic Emissions Inventory System) and MEGAN (Model of Emissions of Gases and Aerosols from Nature) into the atmosphere. In doing so, inconsistencies across model inputs and parameter data are resolved such that the emissions from a particular plant species are consistent with the heat and moisture fluxes calculated for that land cover type. In turn, the response of the atmospheric turbulence and mixing in the planetary boundary layer (PBL) acts on the identical surface type, fluxes, and emissions for each. In addition, the coupling of dust emission within the NU-WRF system is performed in order to ensure consistency and to maximize the benefit of high-resolution land representation in LIS. The impacts of those self-consistent components on' the simulation of atmospheric aerosols are then evaluated through the WRF-Chem-GOCART (Goddard Chemistry Aerosol Radiation and Transport) model. Overall, this ambitious project highlights the current difficulties and future potential of fully coupled. components. in Earth System models, and underscores the importance of the iLEAPS community in supporting improved knowledge of processes and innovative approaches for models and observations.

Quantifying Subsurface Water and Heat Distribution and its Linkage with Landscape Properties in Terrestrial Environment using Hydro-Thermal-Geophysical Monitoring and Coupled Inverse Modeling

NASA Astrophysics Data System (ADS)

Dafflon, B.; Tran, A. P.; Wainwright, H. M.; Hubbard, S. S.; Peterson, J.; Ulrich, C.; Williams, K. H.

2015-12-01

Quantifying water and heat fluxes in the subsurface is crucial for managing water resources and for understanding the terrestrial ecosystem where hydrological properties drive a variety of biogeochemical processes across a large range of spatial and temporal scales. Here, we present the development of an advanced monitoring strategy where hydro-thermal-geophysical datasets are continuously acquired and further involved in a novel inverse modeling framework to estimate the hydraulic and thermal parameter that control heat and water dynamics in the subsurface and further influence surface processes such as evapotranspiration and vegetation growth. The measured and estimated soil properties are also used to investigate co-interaction between subsurface and surface dynamics by using above-ground aerial imaging. The value of this approach is demonstrated at two different sites, one in the polygonal shaped Arctic tundra where water and heat dynamics have a strong impact on freeze-thaw processes, vegetation and biogeochemical processes, and one in a floodplain along the Colorado River where hydrological fluxes between compartments of the system (surface, vadose zone and groundwater) drive biogeochemical transformations. Results show that the developed strategy using geophysical, point-scale and aerial measurements is successful to delineate the spatial distribution of hydrostratigraphic units having distinct physicochemical properties, to monitor and quantify in high resolution water and heat distribution and its linkage with vegetation, geomorphology and weather conditions, and to estimate hydraulic and thermal parameters for enhanced predictions of water and heat fluxes as well as evapotranspiration. Further, in the Colorado floodplain, results document the potential presence of only periodic infiltration pulses as a key hot moment controlling soil hydro and biogeochemical functioning. In the arctic, results show the strong linkage between soil water content, thermal parameters, thaw layer thickness and vegetation distribution. Overall, results of these efforts demonstrate the value of coupling various datasets at high spatial and temporal resolution to improve predictive understanding of subsurface and surface dynamics.

Performance of waste-paper/PETG wood–plastic composites

NASA Astrophysics Data System (ADS)

Huang, Lijie; An, Shuxiang; Li, Chunying; Huang, Chongxing; Wang, Shuangfei; Zhang, Xiaoxiao; Xu, Mingzi; Chen, Jie; Zhou, Lei

2018-05-01

Wood-plastic composites were prepared from polyethylene terephthalate- 1,4-cyclohexanedimethanol ester (PETG) and waste-paper fiber that was unmodified, modified with alkyl-ketene-dimer (AKD), and modified with a silane-coupling agent. The mechanical properties, water absorption properties, surface structure, and thermal properties of the three prepared materials were compared. The results showed that the optimum amount of waste-paper powder is 10 wt%, while that of the waste-paper particles is 60-80 mesh. The use of AKD and coupling agent KH550 can reduce the water absorption of the composite; however, the reductive effect of the coupling agent is better, in that it is reduced by 0.3%. Modification using a 1-wt% KH550 coupling agent can effectively increase the tensile strength of a composite from 31.36 to 41.67 MPa (increase of 32.8%), while the bending strength increased from 86.47 to 98.31 MPa (increase of 13.7%). This also enhances the thermal stability of the composites. With the addition of the coupling agent, the composite material maintains good mechanical properties even after being immersed in water; this can enable the safe use of these composite materials in outdoor environments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, Glenn Edward; Bao, J; Huang, M

Hyporheic exchange is a critical mechanism shaping hydrological and biogeochemical processes along a river corridor. Recent studies on quantifying the hyporheic exchange were mostly limited to local scales due to field inaccessibility, computational demand, and complexity of geomorphology and subsurface geology. Surface flow conditions and subsurface physical properties are well known factors on modulating the hyporheic exchange, but quantitative understanding of their impacts on the strength and direction of hyporheic exchanges at reach scales is absent. In this study, a high resolution computational fluid dynamics (CFD) model that couples surface and subsurface flow and transport is employed to simulate hyporheicmore » exchanges in a 7-km long reach along the main-stem of the Columbia River. Assuming that the hyporheic exchange does not affect surface water flow conditions due to its negligible magnitude compared to the volume and velocity of river water, we developed a one-way coupled surface and subsurface water flow model using the commercial CFD software STAR-CCM+. The model integrates the Reynolds-averaged Navier-Stokes (RANS) equation solver with a realizable κ-ε two-layer turbulence model, a two-layer all y + wall treatment, and the volume of fluid (VOF) method, and is used to simulate hyporheic exchanges by tracking the free water-air interface as well as flow in the river and the subsurface porous media. The model is validated against measurements from acoustic Doppler current profiler (ADCP) in the stream water and hyporheic fluxes derived from a set of temperature profilers installed across the riverbed. The validated model is then employed to systematically investigate how hyporheic exchanges are influenced by surface water fluid dynamics strongly regulated by upstream dam operations, as well as subsurface structures (e.g. thickness of riverbed and subsurface formation layers) and hydrogeological properties (e.g. permeability). The results suggest that the thickness of riverbed alluvium layer is the dominant factor for reach-scale hyporheic exchanges, followed by the alluvium permeability, the depth of the underlying impermeable layer, and the assumption of hydrostatic pressure.« less

Monitoring and Characterizing Seasonal Drought, Water Supply Pattern and Their Impact on Vegetation Growth Using Satellite Soil Moisture Data, GRACE Water Storage and In-situ Observations.

NASA Astrophysics Data System (ADS)

A, G.; Velicogna, I.; Kimball, J. S.; Kim, Y.; Colliander, A.; Njoku, E. G.

2015-12-01

We combine soil moisture (SM) data from AMSR-E, AMSR-2 and SMAP, terrestrial water storage (TWS) changes from GRACE, in-situ groundwater measurements and atmospheric moisture data to delineate and characterize the evolution of drought and its impact on vegetation growth. GRACE TWS provides spatially continuous observations of total terrestrial water storage changes and regional drought extent, persistence and severity, while satellite derived soil moisture estimates provide enhanced delineation of plant-available soil moisture. Together these data provide complementary metrics quantifying available plant water supply. We use these data to investigate the supply changes from water components at different depth in relation to satellite based vegetation metrics, including vegetation greenness (NDVI) measures from MODIS and related higher order productivity (GPP) before, during and following the major drought events observed in the continental US for the past 14 years. We observe consistent trends and significant correlations between monthly time series of TWS, SM, NDVI and GPP. We study how changes in atmosphere moisture stress and coupling of water storage components at different depth impact on the spatial and temporal correlation between TWS, SM and vegetation metrics. In Texas, we find that surface SM and GRACE TWS agree with each other in general, and both capture the underlying water supply constraints to vegetation growth. Triggered by a transit increase in precipitation following the 2011 hydrological drought, vegetation productivity in Texas shows more sensitivity to surface SM than TWS. In the Great Plains, the correspondence between TWS and vegetation productivity is modulated by temperature-induced atmosphere moisture stress and by the coupling between surface soil moisture and groundwater through irrigation.

Feedback of land subsidence on the movement and conjunctive use of water resources

USGS Publications Warehouse

Schmid, Wolfgang; Hanson, Randall T.; Leake, Stanley A.; Hughes, Joseph D.; Niswonger, Richard G.

2014-01-01

The dependency of surface- or groundwater flows and aquifer hydraulic properties on dewatering-induced layer deformation is not available in the USGS's groundwater model MODFLOW. A new integrated hydrologic model, MODFLOW-OWHM, formulates this dependency by coupling mesh deformation with aquifer transmissivity and storage and by linking land subsidence/uplift with deformation-dependent flows that also depend on aquifer head and other flow terms. In a test example, flows most affected were stream seepage and evapotranspiration from groundwater (ETgw). Deformation feedback also had an indirect effect on conjunctive surface- and groundwater use components: Changed stream seepage and streamflows influenced surface-water deliveries and returnflows. Changed ETgw affected irrigation demand, which jointly with altered surface-water supplies resulted in changed supplemental groundwater requirements and pumping and changed return runoff. This modeling feature will improve the impact assessment of dewatering-induced land subsidence/uplift (following irrigation pumping or coal-seam gas extraction) on surface receptors, inter-basin transfers, and surface-infrastructure integrity.

A 1D-2D coupled SPH-SWE model applied to open channel flow simulations in complicated geometries

NASA Astrophysics Data System (ADS)

Chang, Kao-Hua; Sheu, Tony Wen-Hann; Chang, Tsang-Jung

2018-05-01

In this study, a one- and two-dimensional (1D-2D) coupled model is developed to solve the shallow water equations (SWEs). The solutions are obtained using a Lagrangian meshless method called smoothed particle hydrodynamics (SPH) to simulate shallow water flows in converging, diverging and curved channels. A buffer zone is introduced to exchange information between the 1D and 2D SPH-SWE models. Interpolated water discharge values and water surface levels at the internal boundaries are prescribed as the inflow/outflow boundary conditions in the two SPH-SWE models. In addition, instead of using the SPH summation operator, we directly solve the continuity equation by introducing a diffusive term to suppress oscillations in the predicted water depth. The performance of the two approaches in calculating the water depth is comprehensively compared through a case study of a straight channel. Additionally, three benchmark cases involving converging, diverging and curved channels are adopted to demonstrate the ability of the proposed 1D and 2D coupled SPH-SWE model through comparisons with measured data and predicted mesh-based numerical results. The proposed model provides satisfactory accuracy and guaranteed convergence.

The significant surface-water connectivity of "geographically isolated wetlands"

USGS Publications Warehouse

Calhoun, Aram J.K.; Mushet, David M.; Alexander, Laurie C.; DeKeyser, Edward S.; Fowler, Laurie; Lane, Charles R.; Lang, Megan W.; Rains, Mark C.; Richter, Stephen; Walls, Susan

2017-01-01

We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands based on the singular condition of being surrounded by uplands. The most recent research on wetlands considered to be “geographically isolated” shows the difficulties in grouping an ecological resource that does not reliably indicate lack of surface water connectivity in order to meet legal, regulatory, or scientific needs. Additionally, the practice of identifying “geographically isolated wetlands” based on distance from a stream can result in gross overestimates of the number of wetlands lacking ecologically important surface-water connections. Our findings do not support use of the overly simplistic label of “geographically isolated wetlands”. Wetlands surrounded by uplands vary in function and surface-water connections based on wetland landscape setting, context, climate, and geographic region and should be evaluated as such. We found that the “geographically isolated” grouping does not reflect our understanding of the hydrologic variability of these wetlands and hence does not benefit conservation of the Nation’s diverse wetland resources. Therefore, we strongly discourage use of categorizations that provide overly simplistic views of surface-water connectivity of wetlands fully embedded in upland landscapes.

Applying downscaled global climate model data to a hydrodynamic surface-water and groundwater model

USGS Publications Warehouse

Swain, Eric; Stefanova, Lydia; Smith, Thomas

2014-01-01

Precipitation data from Global Climate Models have been downscaled to smaller regions. Adapting this downscaled precipitation data to a coupled hydrodynamic surface-water/groundwater model of southern Florida allows an examination of future conditions and their effect on groundwater levels, inundation patterns, surface-water stage and flows, and salinity. The downscaled rainfall data include the 1996-2001 time series from the European Center for Medium-Range Weather Forecasting ERA-40 simulation and both the 1996-1999 and 2038-2057 time series from two global climate models: the Community Climate System Model (CCSM) and the Geophysical Fluid Dynamic Laboratory (GFDL). Synthesized surface-water inflow datasets were developed for the 2038-2057 simulations. The resulting hydrologic simulations, with and without a 30-cm sea-level rise, were compared with each other and field data to analyze a range of projected conditions. Simulations predicted generally higher future stage and groundwater levels and surface-water flows, with sea-level rise inducing higher coastal salinities. A coincident rise in sea level, precipitation and surface-water flows resulted in a narrower inland saline/fresh transition zone. The inland areas were affected more by the rainfall difference than the sea-level rise, and the rainfall differences make little difference in coastal inundation, but a larger difference in coastal salinities.

Global modeling of withdrawal, allocation and consumptive use of surface water and groundwater resources

NASA Astrophysics Data System (ADS)

Wada, Y.; Wisser, D.; Bierkens, M. F. P.

2014-01-01

To sustain growing food demand and increasing standard of living, global water withdrawal and consumptive water use have been increasing rapidly. To analyze the human perturbation on water resources consistently over large scales, a number of macro-scale hydrological models (MHMs) have been developed in recent decades. However, few models consider the interaction between terrestrial water fluxes, and human activities and associated water use, and even fewer models distinguish water use from surface water and groundwater resources. Here, we couple a global water demand model with a global hydrological model and dynamically simulate daily water withdrawal and consumptive water use over the period 1979-2010, using two re-analysis products: ERA-Interim and MERRA. We explicitly take into account the mutual feedback between supply and demand, and implement a newly developed water allocation scheme to distinguish surface water and groundwater use. Moreover, we include a new irrigation scheme, which works dynamically with a daily surface and soil water balance, and incorporate the newly available extensive Global Reservoir and Dams data set (GRanD). Simulated surface water and groundwater withdrawals generally show good agreement with reported national and subnational statistics. The results show a consistent increase in both surface water and groundwater use worldwide, with a more rapid increase in groundwater use since the 1990s. Human impacts on terrestrial water storage (TWS) signals are evident, altering the seasonal and interannual variability. This alteration is particularly large over heavily regulated basins such as the Colorado and the Columbia, and over the major irrigated basins such as the Mississippi, the Indus, and the Ganges. Including human water use and associated reservoir operations generally improves the correlation of simulated TWS anomalies with those of the GRACE observations.

Global Modeling of Withdrawal, Allocation and Consumptive Use of Surface Water and Groundwater Resources

NASA Astrophysics Data System (ADS)

Wada, Y.; Wisser, D.; Bierkens, M. F.

2014-12-01

To sustain growing food demand and increasing standard of living, global water withdrawal and consumptive water use have been increasing rapidly. To analyze the human perturbation on water resources consistently over large scales, a number of macro-scale hydrological models (MHMs) have been developed in recent decades. However, few models consider the interaction between terrestrial water fluxes, and human activities and associated water use, and even fewer models distinguish water use from surface water and groundwater resources. Here, we couple a global water demand model with a global hydrological model and dynamically simulate daily water withdrawal and consumptive water use over the period 1979-2010, using two re-analysis products: ERA-Interim and MERRA. We explicitly take into account the mutual feedback between supply and demand, and implement a newly developed water allocation scheme to distinguish surface water and groundwater use. Moreover, we include a new irrigation scheme, which works dynamically with a daily surface and soil water balance, and incorporate the newly available extensive global reservoir data set (GRanD). Simulated surface water and groundwater withdrawals generally show good agreement with reported national and sub-national statistics. The results show a consistent increase in both surface water and groundwater use worldwide, with a more rapid increase in groundwater use since the 1990s. Human impacts on terrestrial water storage (TWS) signals are evident, altering the seasonal and inter-annual variability. This alteration is particularly large over heavily regulated basins such as the Colorado and the Columbia, and over the major irrigated basins such as the Mississippi, the Indus, and the Ganges. Including human water use and associated reservoir operations generally improves the correlation of simulated TWS anomalies with those of the GRACE observations.

Polymer subtrates for dry-coupled ultrasonic transducers

NASA Astrophysics Data System (ADS)

Komsky, Igor N.

2003-07-01

Dry-coupled inspection techniques are very important for applications on components with non-uniform surfaces and for inspections of advanced materials or coatings that are porous or otherwise sensitive to the application of water, gel, or some other ultrasonic couplants. To overcome the problems associated with the liquid coupling medium, a number of polymer films have been developed to transmit the ultrasound through a dry interface. These materials are very flexible so even low pressure loading is sufficient to adapt the films to the irregular inspection surfaces. Several polymer films have been evaluated to develop dry-coupled substrates for transducer modules. The modules will be utilized to detect and characterize fatigue cracks and corrosion spots in the aircraft structures. Ultrasonic properties of the polymer films were measured and compared with the properties of plastic or rubber-like materials commonly used for ultrasonic applications. Experiments have been carried out to analyze propagation of longitudinal and shear waves in the films. Two different types of the ultrasonic modules with the flexible polymer substrates are being developed. The influence of the surface condition on the module performance was evaluated for both types of the modules.

Coupling the NASA-CASA ecosystem model with a hydrologic routing algorithm for improved water management in Yosemite National Park

NASA Astrophysics Data System (ADS)

Teaby, A.; Johnson, E. R.; Griffin, M.; Carrillo, C.; Kannan, T.; Shupe, J. W.; Schmidt, C.

2013-12-01

Historic trends reveal extreme precipitation variability within the Yosemite National Park (YNP) geographic region. While California obtains greater than half of its annual water supply from the Sierra Nevada, snowpack, precipitation, and runoff can fluctuate between less than 50% and greater than 200% of climatological averages. Advances in hydrological modeling are crucial to improving water-use efficiency at the local, state, and national levels. The NASA Carnegie Ames Stanford Approach (CASA) is a global simulation model that combines multi-year satellite, climate, and other land surface databases to estimate biosphere-atmosphere exchange of energy, water, and trace gases from plants and soils. By coupling CASA with a Hydrological Routing Algorithm known as HYDRA, it is possible to calculate current water availability and observe hydrological trends within YNP. Satellite-derived inputs such as surface evapotranspiration, temperature, precipitation, land cover, and elevation were included to create a valuable decision support tool for YNP's water resource managers. These results will be of enhanced importance given current efforts to restore 81 miles of the Merced River within the park's boundary. Validations of model results were conducted using in situ stream gage measurements. The model accurately simulated observed streamflow values, achieving a relatively strong Nash-Sutcliffe model efficiency coefficient. This geospatial assessment provides a standardized method which may be repeated in both national and international water-stressed regions.

Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover

DOE PAGES

Stegen, James C.; Fredrickson, James K.; Wilkins, Michael J.; ...

2016-04-07

Environmental transition zones are associated with geochemical gradients that overcome energy limitations to microbial metabolism, resulting in biogeochemical hot spots and moments. Riverine systems where groundwater mixes with surface water (the hyporheic zone) are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. To investigate the coupling among groundwater-surface water mixing, microbial communities, and biogeochemistry we applied ecological theory, aqueous biogeochemistry, DNA sequencing, and ultra-high resolution organic carbon profiling to field samples collected across times and locations representing amore » broad range of mixing conditions. Mixing of groundwater and surface water resulted in a shift from transport-driven stochastic dynamics to a deterministic microbial structure associated with elevated biogeochemical rates. While the dynamics of the hyporheic make predictive modeling a challenge, we provide new knowledge that can improve the tractability of such models.« less

A coupled dynamic-thermodynamic model of an ice-ocean system in the marginal ice zone

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa

1987-01-01

Thermodynamics are incorporated into a coupled ice-ocean model in order to investigate wind-driven ice-ocean processes in the marginal zone. Upswelling at the ice edge which is generated by the difference in the ice-air and air-water surface stresses is found to give rise to a strong entrainment by drawing the pycnocline closer to the surface. Entrainment is shown to be negligible outside the areas affected by the ice edge upswelling. If cooling at the top is included in the model, the heat and salt exchanges are further enhanced in the upswelling areas. It is noted that new ice formation occurs in the region not affected by ice edge upswelling, and it is suggested that the high-salinity mixed layer regions (with a scale of a few Rossby radii of deformation) will overturn due to cooling, possibly contributing to the formation of deep water.

OSOAA: A Vector Radiative Transfer Model of Coupled Atmosphere-Ocean System for a Rough Sea Surface Application to the Estimates of the Directional Variations of the Water Leaving Reflectance to Better Process Multi-angular Satellite Sensors Data Over the Ocean

NASA Technical Reports Server (NTRS)

Chami, Malik; LaFrance, Bruno; Fougnie, Bertrand; Chowdhary, Jacek; Harmel, Tristan; Waquet, Fabien

2015-01-01

In this study, we present a radiative transfer model, so-called OSOAA, that is able to predict the radiance and degree of polarization within the coupled atmosphere-ocean system in the presence of a rough sea surface. The OSOAA model solves the radiative transfer equation using the successive orders of scattering method. Comparisons with another operational radiative transfer model showed a satisfactory agreement within 0.8%. The OSOAA model has been designed with a graphical user interface to make it user friendly for the community. The radiance and degree of polarization are provided at any level, from the top of atmosphere to the ocean bottom. An application of the OSOAA model is carried out to quantify the directional variations of the water leaving reflectance and degree of polarization for phytoplankton and mineral-like dominated waters. The difference between the water leaving reflectance at a given geometry and that obtained for the nadir direction could reach 40%, thus questioning the Lambertian assumption of the sea surface that is used by inverse satellite algorithms dedicated to multi-angular sensors. It is shown as well that the directional features of the water leaving reflectance are weakly dependent on wind speed. The quantification of the directional variations of the water leaving reflectance obtained in this study should help to correctly exploit the satellite data that will be acquired by the current or forthcoming multi-angular satellite sensors.

Hybrid Eulerian and Lagrangian Simulation of Steep and Breaking Waves and Surface Fluxes in High Winds

DTIC Science & Technology

2012-09-30

Lagrangian methods for free - surface turbulence and wave simulation . In the far field, coupled wind and wave simulations are used to obtain wind...to conserve the mass precisely. When the wave breaks, the flow at the free surface may become very violent, air and water may be highly mixed...fluids free - surface flows that can be used to study the fundamental physics of wave breaking. The research will improve the understanding of air-sea

An emerging reactor technology for chemical synthesis: surface acoustic wave-assisted closed-vessel Suzuki coupling reactions.

PubMed

Kulkarni, Ketav; Friend, James; Yeo, Leslie; Perlmutter, Patrick

2014-07-01

In this paper we demonstrate the use of an energy-efficient surface acoustic wave (SAW) device for driving closed-vessel SAW-assisted (CVSAW), ligand-free Suzuki couplings in aqueous media. The reactions were carried out on a mmolar scale with low to ultra-low catalyst loadings. The reactions were driven by heating resulting from the penetration of acoustic energy derived from RF Raleigh waves generated by a piezoelectric chip via a renewable fluid coupling layer. The yields were uniformly high and the reactions could be executed without added ligand and in water. In terms of energy density this new technology was determined to be roughly as efficient as microwaves and superior to ultrasound. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

The ecohydrology of water limited landscapes

NASA Astrophysics Data System (ADS)

Huxman, T. E.

2011-12-01

Developing a mechanistic understanding of the coupling of ecological and hydrological systems is crucial for understanding the land-surface response of large areas of the globe to changes in climate. The distribution of biodiversity, the quantity and quality of streamflow, the biogeochemistry that constrains vegetation cover and production, and the stability of soil systems in watersheds are all functions of water-life coupling. Many key ecosystem services are governed by the dynamics of near-surface hydrology and biological feedbacks on the landscape occur through plant influence over available soil moisture. Thus, ecohydrology has tremendous potential to contribute to a predictive framework for understanding earth system dynamics. Despite the importance of such couplings and water as a major limiting resource in ecosystems throughout the globe, ecology still struggles with a mechanistic understanding of how changes in rainfall affect the biology of plants and microbes, or how changes in plant communities affect hydrological dynamics in watersheds. Part of the problem comes from our lack of understanding of how plants effectively partition available water among individuals in communities and how that modifies the physical environment, affecting additional resource availability and the passage of water along other hydrological pathways. The partitioning of evapotranspiration between transpiration by plants and evaporation from the soil surface is key to interrelated ecological, hydrological, and atmospheric processes and likely varies with vegetation structure and atmospheric dynamics. In addition, the vertical stratification of autotrophic and heterotrophic components in the soil profile, and the speed at which each respond to increased water, exert strong control over the carbon cycle. The magnitude of biosphere-atmosphere carbon exchange depends on the time-depth-distribution of soil moisture, a fundamental consequence of local precipitation pulse characteristics, soil texture and plant functional type. The transport of metabolic products within plants and their differential activation result in non-intuitive patterns of exchange associated with the major drivers creating problems with the scaling of physiological processes of individual plants to ecosystems. Such dynamics, along with hysteretic behavior creates challenges for measurement, evaluation, modeling and predicting ecosystem behavior. New frameworks and conceptual approaches to modeling ecosystem metabolism and the role of water are helping to describe the consequences of precipitation variability and change.

Future change of water vaiables from HadGEM2-AO simulation

NASA Astrophysics Data System (ADS)

Kim, Moon-Hyun; Kang, Hyun-Suk; Lee, Johan; Baek, Hee-Jeong; Cho, Chunho

2013-04-01

Complex global models developed for climate prediction are now applied to the future climate projection in a number of global modeling centers around the world. In climate prediction aspects, an atmosphere-ocean coupled model (one-tier climate system) has been recognized to exhibit useful skill for a global or certain regions (Graham et al., 2005). Wang et al. (2005) demonstrates that an AGCM coupled with an ocean model, simulates realistic SST-rainfall relationships for the Asia during the summer period. Also the transition from two-tier to one-tier approach in climate prediction are mainly caused by recent progresses in development of coupled climate models and enlargement of understanding air-sea interactions obtained from international collaborative efforts such as TOGA (the Tropical Ocean-Global Atmosphere) program (Wang et al., 2009). Meanwhile, water resource including river outflow in association with surface and sub-surface water flow is an important part of the global hydrological cycle, and is affected by climate variability and change through recharge processes (Chen et al., 2002), as well as by human interventions in many locations (Petheram et al., 2001). Also, water is critical resource to the social, economic and environmental aspects, and advances of these core elements requires improved water resource management. Better management and use of water need to abundant real time hydro-meteorological (river and weather) information as well as accurate water resource forecasting (Barrett, 1990). For this reason, many studies have recently carrying out the water resource prediction and estimation using hydrology and climate model. For example, Shiklomanov et al. (2011) predicted that water resource in Russian territory increases about 8-10% during 2010-2020 using the unit hydrograph (UH) model based on hydrologic rainfall-runoff model. Anderson et al. (2000) explained the probabilistic seasonal prediction of drought with a simplified climate model coupled hydrology-atmosphere for water resource planning. Arora et al. (1999) and Oki and Sud (1998) developed a method for routing river flows through GCM grid cells. Accordingly, reliable forecasts are expected to help water managers and users with long lead time decisions, leading to greater water use efficiency and better risk management (Wang, 2012). SO, we analysed hydrological cycle and drought index from precipitation, evaporation, runoff, soil moisture, river outflow, and so on using atmosphere-ocean coupled model which called by HadGEM2-AO. Details and added information by this climate projection system about the future water cycle's change will be presented at the workshop. Acknowledgments: This research has been supported by project NIMR-2013-B-2 of the National Institute of Meteorological Research in Korea Meteorological Administration.

Large heat capacity change in a protein-monovalent cation interaction.

PubMed

Guinto, E R; Di Cera, E

1996-07-09

Current views about protein-ligand interactions state that electrostatic forces drive the binding of charged species and that burial of hydrophobic and polar surfaces controls the heat capacity change associated with the reaction. For the interaction of a protein with a monovalent cation the electrostatic components are expected to be significant due to the ionic nature of the ligand, whereas the heat capacity change is expected to be small due to the size of the surface area involved in the recognition event. The physiologically important interaction of Na+ with thrombin was studied over the temperature range from 5 to 45 degrees C and the ionic strength range from 50 to 800 mM. These measurements reveal an unanticipated result that bears quite generally on studies of molecular recognition and protein folding. Binding of Na+ to thrombin is characterized by a modest dependence on ionic strength but a large and negative heat capacity change of -1.1 +/- 0.1 kcal mol-1 K-1. The small electrostatic coupling can be explained in terms of a minimal perturbation of the ionic atmosphere of the protein upon Na+ binding. The large heat capacity change, however, is difficult to reconcile with current views on the origin of this effect from surface area changes or large folding transitions coupled to binding. It is proposed that this change is linked to burial of a large cluster of water molecules in the Na+ binding pocket upon Na+ binding. Due to their reduced mobility and highly ordered structure, water molecules sequestered in the interior of a protein must have a lower heat capacity compared to those on the surface of a protein or in the bulk solvent. Hence, a binding or folding event where water molecules are buried may result in significant heat capacity changes independent of changes in exposed hydrophobic surface or coupled conformational transitions.

The Central Valley Hydrologic Model

NASA Astrophysics Data System (ADS)

Faunt, C.; Belitz, K.; Hanson, R. T.

2009-12-01

Historically, California’s Central Valley has been one of the most productive agricultural regions in the world. The Central Valley also is rapidly becoming an important area for California’s expanding urban population. In response to this competition for water, a number of water-related issues have gained prominence: conjunctive use, artificial recharge, hydrologic implications of land-use change, subsidence, and effects of climate variability. To provide information to stakeholders addressing these issues, the USGS made a detailed assessment of the Central Valley aquifer system that includes the present status of water resources and how these resources have changed over time. The principal product of this assessment is a tool, referred to as the Central Valley Hydrologic Model (CVHM), that simulates surface-water flows, groundwater flows, and land subsidence in response to stresses from human uses and from climate variability throughout the entire Central Valley. The CVHM utilizes MODFLOW combined with a new tool called “Farm Process” to simulate groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis. This model was discretized horizontally into 20,000 1-mi2 cells and vertically into 10 layers ranging in thickness from 50 feet at the land surface to 750 feet at depth. A texture model constructed by using data from more than 8,500 drillers’ logs was used to estimate hydraulic properties. Unmetered pumpage and surface-water deliveries for 21 water-balance regions were simulated with the Farm Process. Model results indicate that human activities, predominately surface-water deliveries and groundwater pumping for irrigated agriculture, have dramatically influenced the hydrology of the Central Valley. These human activities have increased flow though the aquifer system by about a factor of six compared to pre-development conditions. The simulated hydrology reflects spatial and temporal variability in climate, land-use changes, and available surface-water deliveries. For example, the droughts of 1976-77 and 1987-92 led to reduced streamflow and surface-water deliveries and increased evapotranspiration and groundwater pumpage throughout most of the valley, resulting in a decrease in groundwater storage. Since the mid-1990s, annual surface-water deliveries generally have exceeded groundwater pumpage, resulting in an increase or no change in groundwater storage throughout most of the valley. However, groundwater is still being removed from storage during most years in the southern part of the Central Valley. The CVHM is designed to be coupled with Global Climate Models to forecast the potential supply of surface-water deliveries, demand for groundwater pumpage, potential subsidence, and changes in groundwater storage in response to different climate-change scenarios. The detailed database on texture properties coupled with CVHM's ability to simulate the combined effects of recharge and discharge make CVHM particularly useful for assessing water-management plans, such as conjunctive water use, conservation of agriculture land, and land-use change. In the future, the CVHM could be used in conjunction with optimization models to help evaluate water-management alternatives to effectively utilize the available water resources.

Simulation of groundwater and surface-water resources and evaluation of water-management alternatives for the Chamokane Creek basin, Stevens County, Washington

USGS Publications Warehouse

Ely, D. Matthew; Kahle, Sue C.

2012-01-01

A three-dimensional, transient numerical model of groundwater and surface-water flow was constructed for Chamokane Creek basin to better understand the groundwater-flow system and its relation to surface-water resources. The model described in this report can be used as a tool by water-management agencies and other stakeholders to quantitatively evaluate the effects of potential increases in groundwater pumping on groundwater and surface-water resources in the basin. The Chamokane Creek model was constructed using the U.S. Geological Survey (USGS) integrated model, GSFLOW. GSFLOW was developed to simulate coupled groundwater and surface-water resources. The model uses 1,000-foot grid cells that subdivide the model domain by 102 rows and 106 columns. Six hydrogeologic units in the model are represented using eight model layers. Daily precipitation and temperature were spatially distributed and subsequent groundwater recharge was computed within GSFLOW. Streamflows in Chamokane Creek and its major tributaries are simulated in the model by routing streamflow within a stream network that is coupled to the groundwater-flow system. Groundwater pumpage and surface-water diversions and returns specified in the model were derived from monthly and annual pumpage values previously estimated from another component of this study and new data reported by study partners. The model simulation period is water years 1980-2010 (October 1, 1979, to September 30, 2010), but the model was calibrated to the transient conditions for water years 1999-2010 (October 1, 1998, to September 30, 2010). Calibration was completed by using traditional trial-and-error methods and automated parameter-estimation techniques. The model adequately reproduces the measured time-series groundwater levels and daily streamflows. At well observation points, the mean difference between simulated and measured hydraulic heads is 7 feet with a root-mean-square error divided by the total difference in water levels of 4.7 percent. Simulated streamflow was compared to measured streamflow at the USGS streamflow-gaging station-Chamokane Creek below Falls, near Long Lake (12433200). Annual differences between measured and simulated streamflow for the site ranged from -63 to 22 percent. Calibrated model output includes a 31-year estimate of monthly water budget components for the hydrologic system. Five model applications (scenarios) were completed to obtain a better understanding of the relation between groundwater pumping and surface-water resources. The calibrated transient model was used to evaluate: (1) the connection between the upper- and middle-basin groundwater systems, (2) the effect of surface-water and groundwater uses in the middle basin, (3) the cumulative impacts of claims registry use and permit-exempt wells on Chamokane Creek streamflow, (4) the frequency of regulation due to impacted streamflow, and (5) the levels of domestic and stockwater use that can be regulated. The simulation results indicated that streamflow is affected by existing groundwater pumping in the upper and middle basins. Simulated water-management scenarios show streamflow increased relative to historical conditions as groundwater and surface-water withdrawals decreased.

Integration of nitrogen dynamics into the Noah-MP land surface model v1.1 for climate and environmental predictions

NASA Astrophysics Data System (ADS)

Cai, X.; Yang, Z.-L.; Fisher, J. B.; Zhang, X.; Barlage, M.; Chen, F.

2016-01-01

Climate and terrestrial biosphere models consider nitrogen an important factor in limiting plant carbon uptake, while operational environmental models view nitrogen as the leading pollutant causing eutrophication in water bodies. The community Noah land surface model with multi-parameterization options (Noah-MP) is unique in that it is the next-generation land surface model for the Weather Research and Forecasting meteorological model and for the operational weather/climate models in the National Centers for Environmental Prediction. In this study, we add a capability to Noah-MP to simulate nitrogen dynamics by coupling the Fixation and Uptake of Nitrogen (FUN) plant model and the Soil and Water Assessment Tool (SWAT) soil nitrogen dynamics. This model development incorporates FUN's state-of-the-art concept of carbon cost theory and SWAT's strength in representing the impacts of agricultural management on the nitrogen cycle. Parameterizations for direct root and mycorrhizal-associated nitrogen uptake, leaf retranslocation, and symbiotic biological nitrogen fixation are employed from FUN, while parameterizations for nitrogen mineralization, nitrification, immobilization, volatilization, atmospheric deposition, and leaching are based on SWAT. The coupled model is then evaluated at the Kellogg Biological Station - a Long Term Ecological Research site within the US Corn Belt. Results show that the model performs well in capturing the major nitrogen state/flux variables (e.g., soil nitrate and nitrate leaching). Furthermore, the addition of nitrogen dynamics improves the modeling of net primary productivity and evapotranspiration. The model improvement is expected to advance the capability of Noah-MP to simultaneously predict weather and water quality in fully coupled Earth system models.

Ab Initio Metadynamics Study of the VO2+/VO2+ Redox Reaction Mechanism at the Graphite Edge/Water Interface.

PubMed

Jiang, Zhen; Klyukin, Konstantin; Alexandrov, Vitaly

2018-06-20

Redox flow batteries (RFBs) are promising electrochemical energy storage systems, for which development is impeded by a poor understanding of redox reactions occurring at electrode/electrolyte interfaces. Even for the conventional all-vanadium RFB chemistry employing V 2+ /V 3+ and VO 2 + /VO 2+ couples, there is still no consensus about the reaction mechanism, electrode active sites, and rate-determining step. Herein, we perform Car-Parrinello molecular dynamics-based metadynamics simulations to unravel the mechanism of the VO 2 + /VO 2+ redox reaction in water at the oxygen-functionalized graphite (112̅0) edge surface serving as a representative carbon-based electrode. Our results suggest that during the battery discharge aqueous VO 2 + /VO 2+ species adsorb at the surface C-O groups as inner-sphere complexes, exhibiting faster adsorption/desorption kinetics than V 2+ /V 3+ , at least at low vanadium concentrations considered in our study. We find that this is because (i) VO 2 + /VO 2+ conversion does not involve the slow transfer of an oxygen atom, (ii) protonation of VO 2 + is spontaneous and coupled to interfacial electron transfer in acidic conditions to enable VO 2+ formation, and (iii) V 3+ found to be strongly bound to oxygen groups of the graphite surface features unfavorable desorption kinetics. In contrast, the reverse process taking place upon charging is expected to be more sluggish for the VO 2 + /VO 2+ redox couple because of both unfavorable deprotonation of the VO 2+ water ligands and adsorption/desorption kinetics.

Modeling thermal dynamics of active layer soils and near-surface permafrost using a fully coupled water and heat transport model

USGS Publications Warehouse

Jiang, Yueyang; Zhuang, Qianlai; O'Donnell, Jonathan A.

2012-01-01

Thawing and freezing processes are key components in permafrost dynamics, and these processes play an important role in regulating the hydrological and carbon cycles in the northern high latitudes. In the present study, we apply a well-developed soil thermal model that fully couples heat and water transport, to simulate the thawing and freezing processes at daily time steps across multiple sites that vary with vegetation cover, disturbance history, and climate. The model performance was evaluated by comparing modeled and measured soil temperatures at different depths. We use the model to explore the influence of climate, fire disturbance, and topography (north- and south-facing slopes) on soil thermal dynamics. Modeled soil temperatures agree well with measured values for both boreal forest and tundra ecosystems at the site level. Combustion of organic-soil horizons during wildfire alters the surface energy balance and increases the downward heat flux through the soil profile, resulting in the warming and thawing of near-surface permafrost. A projection of 21st century permafrost dynamics indicates that as the climate warms, active layer thickness will likely increase to more than 3 meters in the boreal forest site and deeper than one meter in the tundra site. Results from this coupled heat-water modeling approach represent faster thaw rates than previously simulated in other studies. We conclude that the discussed soil thermal model is able to well simulate the permafrost dynamics and could be used as a tool to analyze the influence of climate change and wildfire disturbance on permafrost thawing.

Observational Evidence for Desert Amplification Using Multiple Satellite Datasets.

PubMed

Wei, Nan; Zhou, Liming; Dai, Yongjiu; Xia, Geng; Hua, Wenjian

2017-05-17

Desert amplification identified in recent studies has large uncertainties due to data paucity over remote deserts. Here we present observational evidence using multiple satellite-derived datasets that desert amplification is a real large-scale pattern of warming mode in near surface and low-tropospheric temperatures. Trend analyses of three long-term temperature products consistently confirm that near-surface warming is generally strongest over the driest climate regions and this spatial pattern of warming maximizes near the surface, gradually decays with height, and disappears in the upper troposphere. Short-term anomaly analyses show a strong spatial and temporal coupling of changes in temperatures, water vapor and downward longwave radiation (DLR), indicating that the large increase in DLR drives primarily near surface warming and is tightly associated with increasing water vapor over deserts. Atmospheric soundings of temperature and water vapor anomalies support the results of the long-term temperature trend analysis and suggest that desert amplification is due to comparable warming and moistening effects of the troposphere. Likely, desert amplification results from the strongest water vapor feedbacks near the surface over the driest deserts, where the air is very sensitive to changes in water vapor and thus efficient in enhancing the longwave greenhouse effect in a warming climate.

Divergent surface and total soil moisture projections under global warming

USGS Publications Warehouse

Berg, Alexis; Sheffield, Justin; Milly, Paul C.D.

2017-01-01

Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, total, and layer-by-layer soil moisture. We identify a robust vertical gradient of projected mean soil moisture changes, with more negative changes near the surface. Some regions of the northern middle to high latitudes exhibit negative annual surface changes but positive total changes. We interpret this behavior in the context of seasonal changes in the surface water budget. This vertical pattern implies that the extensive drying predicted by off-line drought metrics, while consistent with the projected decline in surface soil moisture, will tend to overestimate (negatively) changes in total soil water availability.

Study of the Effect of Turbulence and Large Obstacles on the Evaporation from Bare Soil Surface through Coupled Free-flow and Porous-medium Flow Model

NASA Astrophysics Data System (ADS)

Gao, B.; Smits, K. M.

2017-12-01

Evaporation is a strongly coupled exchange process of mass, momentum and energy between the atmosphere and the soil. Several mechanisms influence evaporation, such as the atmospheric conditions, the structure of the soil surface, and the physical properties of the soil. Among the previous studies associated with evaporation modeling, most efforts use uncoupled models which simplify the influences of the atmosphere and soil through the use of resistance terms. Those that do consider the coupling between the free flow and porous media flow mainly consider flat terrain with grain-scale roughness. However, larger obstacles, which may form drags or ridges allowing normal convective air flow through the soil, are common in nature and may affect the evaporation significantly. Therefore, the goal of this work is to study the influence of large obstacles such as wavy surfaces on the flow behavior within the soil and exchange processes to the atmosphere under turbulent free-flow conditions. For simplicity, the soil surface with large obstacles are represented by a simple wavy surface. To do this, we modified a previously developed theory for two-phase two-component porous-medium flow, coupling it to single-phase two-component turbulent flow to simulate and analyze the evaporation from wavy soil surfaces. Detailed laboratory scale experiments using a wind tunnel interfaced with a porous media tank were carried out to test the modeling results. The characteristics of turbulent flow across a permeable wavy surface are discussed. Results demonstrate that there is an obvious recirculation zone formed at the surface, which is special because of the accumulation of water vapor and the thicker boundary layer in this area. In addition, the influences of both the free flow and porous medium on the evaporation are also analyzed. The porous medium affects the evaporation through the amount of water it can provide to the soil surface; while the atmosphere influences the evaporation through the gradients formed within the boundary layer. This study gives a primary cognition on the evaporation from bare soil surface with obstacles. Ongoing work will include a deep understanding of the mechanisms which may provide the basis for land-atmosphere study on field scale.

Groundwater-Surface Water Interaction: A Case Study of Embankment Dam Safety Assessment in Sweden.

NASA Astrophysics Data System (ADS)

Ferdos, F.; Dargahi, B.

2015-12-01

Seepage, when excessive and unimpeded, can cause embankment dam failure. Such failures are often initiated by internal erosion and piping. Modelling these phenomena in embankment dams, accounting for the groundwater-surface water interactions, is crucial when performing dam safety assessments. The aim of this study was to evaluate the applicability of modelling seepage flows in multi-region dams using a finite element based multi-physics model. The model was applied to the Trängslet dam, the largest dam in Sweden. The objectives were to analyze the characteristics of both the flow and the surface-ground water interactions occurring in the dam, including: i) the saturated and unsaturated laminar flow regimes within the dam body, ii) the non-linear through-flow in the dam shoulders' coarse material, iii) the influence of the surface waves in the reservoir on the seepage flow by coupling the physics to a hydrodynamic interface, and iv) the influence of a conceptual "erosion tunnel" on the seepage flow and its interaction with the surface water flow by coupling the physics to a CFD interface. The focus of the study was on the influence of the transient water head boundary condition, surface waves and the internal erosion tunnel on the location of the phreatic line and the seepage flow rate. The simulated seepage flow of the dam in its original condition tallied with the monitoring measurements (40-70 l/s). The main feature found was the relatively high position of the phreatic line, which could compromise the stability of the dam. The combination of the seepage model with the reservoir hydrodynamics indicated a negligible influence of the surface waves on seepage flow. Results from the combination of the seepage model with fluid dynamics indicated that a conceptual "erosion tunnel" placed within the dam, even as high as in the unsaturated zone, significantly affects the phreatic line's position. This also causes the seepage flow to increase by several orders of magnitude, resulting in non-linear turbulent flow regimes in the downstream shoulder of the dam and, ultimately, dam failure. While the modelling was limited by a lack of reliable geometrical and geotechnical data, the results of the study do highlight the importance of including groundwater-surface water interactions in dam safety assessments.

Water interaction with hydrophobic and hydrophilic soot particles.

PubMed

Popovicheva, Olga; Persiantseva, Natalia M; Shonija, Natalia K; DeMott, Paul; Koehler, Kirsten; Petters, Markus; Kreidenweis, Sonia; Tishkova, Victoria; Demirdjian, Benjamin; Suzanne, Jean

2008-05-07

The interaction of water with laboratory soots possessing a range of properties relevant for atmospheric studies is examined by two complementary methods: gravimetrical measurement of water uptake coupled with chemical composition and porosity analysis and HTDMA (humidified tandem differential mobility analyzer) inference of water uptake accompanied by separate TEM (transmission electron microscopy) analysis of single particles. The first method clarifies the mechanism of water uptake for bulk soot and allows the classification of soot with respect to its hygroscopicity. The second method highlights the dependence of the soot aerosol growth factor on relative humidity (RH) for quasi-monodisperse particles. Hydrophobic and hydrophilic soot are qualitatively defined by their water uptake and surface polarity: laboratory soot particles are thus classified from very hydrophobic to very hydrophilic. Thermal soot particles produced from natural gas combustion are classified as hydrophobic with a surface of low polarity since water is found to cover only half of the surface. Graphitized thermal soot particles are proposed for comparison as extremely hydrophobic and of very low surface polarity. Soot particles produced from laboratory flame of TC1 aviation kerosene are less hydrophobic, with their entire surface being available for statistical monolayer water coverage at RH approximately 10%. Porosity measurements suggest that, initially, much of this surface water resides within micropores. Consequently, the growth factor increase of these particles to 1.07 at RH > 80% is attributed to irreversible swelling that accompanies water uptake. Hysteresis of adsorption/desorption cycles strongly supports this conclusion. In contrast, aircraft engine soot, produced from burning TC1 kerosene in a gas turbine engine combustor, has an extremely hydrophilic surface of high polarity. Due to the presence of water soluble organic and inorganic material it can be covered by many water layers even below water saturation conditions. This soot demonstrates a gradual diameter growth factor (D(wet)/D(dry)) increase up to 1.22 at 93% relative humidity, most likely due to the presence of single particles with water soluble material heterogeneously distributed over their surface.

Effects of Dimethyl Sulfoxide on Surface Water near Phospholipid Bilayers.

PubMed

Lee, Yuno; Pincus, Philip A; Hyeon, Changbong

2016-12-06

Despite much effort to probe the properties of dimethyl sulfoxide (DMSO) solution, the effects of DMSO on water, especially near plasma membrane surfaces, still remain elusive. By performing molecular dynamics simulations at varying DMSO concentrations (X DMSO ), we study how DMSO affects structural and dynamical properties of water in the vicinity of phospholipid bilayers. As proposed by a number of experiments, our simulations confirm that DMSO induces dehydration from bilayer surfaces and disrupts the H-bond structure of water. However, DMSO-enhanced water diffusivity at solvent-bilayer interfaces, an intriguing discovery reported by a spin-label measurement, is not confirmed in our simulations. To resolve this discrepancy, we examine the location of the spin label (Tempo) relative to the solvent-bilayer interface. In accord with the evidence in the literature, our simulations, which explicitly model Tempo-phosphatidylcholine, find that the Tempo moiety is equilibrated at ∼8-10 Å below the bilayer surface. Furthermore, the DMSO-enhanced surface-water diffusion is confirmed only when water diffusion is analyzed around the Tempo moiety that is immersed below the bilayer surface, which implies that the experimentally detected signal of water using Tempo stems from the interior of bilayers, not from the interface. Our analysis finds that the increase of water diffusion below the bilayer surface is coupled to the increase of area per lipid with an increasing X DMSO (≲10mol%). Underscoring the hydrophobic nature of the Tempo moiety, our study calls for careful re-evaluation of the use of Tempo in measurements on lipid bilayer surfaces. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

A second-order Budkyo-type parameterization of landsurface hydrology

NASA Technical Reports Server (NTRS)

Andreou, S. A.; Eagleson, P. S.

1982-01-01

A simple, second order parameterization of the water fluxes at a land surface for use as the appropriate boundary condition in general circulation models of the global atmosphere was developed. The derived parameterization incorporates the high nonlinearities in the relationship between the near surface soil moisture and the evaporation, runoff and percolation fluxes. Based on the one dimensional statistical dynamic derivation of the annual water balance, it makes the transition to short term prediction of the moisture fluxes, through a Taylor expansion around the average annual soil moisture. A comparison of the suggested parameterization is made with other existing techniques and available measurements. A thermodynamic coupling is applied in order to obtain estimations of the surface ground temperature.

Evaluation of Modeling Schemes to Estimate Evapotranspiration and Root Zone Soil Water Content over Vineyard using a Scintillometer and Remotely Sensed Surface Energy Balance

NASA Astrophysics Data System (ADS)

Geli, H. M. E.; Gonzalez-Piqueras, J.; Isidro, C., Sr.

2016-12-01

Actual crop evapotranspiration (ETa) and root zone soil water content (SMC) are key operational variable to monitor water consumption and water stress condition for improve vineyard grapes productivity and quality. This analysis, evaluates the estimation of ETa and SMC based on two modeling approaches. The first approach is a hybrid model that couples a thermal-based two source energy balance (TSEB) model (Norman et al. 1995) and water balance model to estimate the two variable (Geli 2012). The second approach is based on Large Aperture Scintillometer (LAS)-based estimates of sensible heat flux. The LAS-based estimates of sensible heat fluxes were used to calculate latent heat flux as the residual of surface energy balance equation on hourly basis which was converted to daily ETa. The calculated ETa from the scintillometer was then couple with the water balance approach to provide updated ETa_LAS and SMC_LAS. Both estimates of ETa and SMC based on LAS (i.e. ETa_LAS and SMC_LAS) and TSEB (ETa_TSEB and SMC_TSEB) were compared with ground-based observation from eddy covariance and soil water content measurements at multiple depths. The study site is an irrigated vineyard located in Central Spain Primary with heterogeneous surface conditions in term of irrigation practices and the ground based observation over the vineyard were collected during the summer of 2007. Preliminary results of the inter-comparison of the two approaches suggests relatively good between both modeling approaches and ground-based observations with RMSE lower than 1.2 mm/day for ETa and lower than 20% for SMC. References Norman, J. M., Kustas, W. P., & Humes, K. S. (1995). A two-source approach for estimating soil and vegetation energy fluxes in observations of directional radiometric surface temperature. Agricultural and Forest Meteorology, 77, 263293. Geli, Hatim M. E. (2012). Modeling spatial surface energy fluxes of agricultural and riparian vegetation using remote sensing, Ph. D. dissertation, Department of Civil and Environmental Engineering, Utah State University.

Improving National Water Modeling: An Intercomparison of two High-Resolution, Continental Scale Models, CONUS-ParFlow and the National Water Model

NASA Astrophysics Data System (ADS)

Tijerina, D.; Gochis, D.; Condon, L. E.; Maxwell, R. M.

2017-12-01

Development of integrated hydrology modeling systems that couple atmospheric, land surface, and subsurface flow is growing trend in hydrologic modeling. Using an integrated modeling framework, subsurface hydrologic processes, such as lateral flow and soil moisture redistribution, are represented in a single cohesive framework with surface processes like overland flow and evapotranspiration. There is a need for these more intricate models in comprehensive hydrologic forecasting and water management over large spatial areas, specifically the Continental US (CONUS). Currently, two high-resolution, coupled hydrologic modeling applications have been developed for this domain: CONUS-ParFlow built using the integrated hydrologic model ParFlow and the National Water Model that uses the NCAR Weather Research and Forecasting hydrological extension package (WRF-Hydro). Both ParFlow and WRF-Hydro include land surface models, overland flow, and take advantage of parallelization and high-performance computing (HPC) capabilities; however, they have different approaches to overland subsurface flow and groundwater-surface water interactions. Accurately representing large domains remains a challenge considering the difficult task of representing complex hydrologic processes, computational expense, and extensive data needs; both models have accomplished this, but have differences in approach and continue to be difficult to validate. A further exploration of effective methodology to accurately represent large-scale hydrology with integrated models is needed to advance this growing field. Here we compare the outputs of CONUS-ParFlow and the National Water Model to each other and with observations to study the performance of hyper-resolution models over large domains. Models were compared over a range of scales for major watersheds within the CONUS with a specific focus on the Mississippi, Ohio, and Colorado River basins. We use a novel set of approaches and analysis for this comparison to better understand differences in process and bias. This intercomparison is a step toward better understanding how much water we have and interactions between surface and subsurface. Our goal is to advance our understanding and simulation of the hydrologic system and ultimately improve hydrologic forecasts.

Organic Matter Remineralization Predominates Phosphorus Cycling in the Mid-Bay Sediments in the Chesapeake Bay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sunendra, Joshi R.; Kukkadapu, Ravi K.; Burdige, David J.

2015-05-19

The Chesapeake Bay, the largest and most productive estuary in the US, suffers from varying degrees of water quality issues fueled by both point and non–point source nutrient sources. Restoration of the bay is complicated by the multitude of nutrient sources, their variable inputs and hydrological conditions, and complex interacting factors including climate forcing. These complexities not only restrict formulation of effective restoration plans but also open up debates on accountability issues with nutrient loading. A detailed understanding of sediment phosphorus (P) dynamics enables one to identify the exchange of dissolved constituents across the sediment- water interface and aid tomore » better constrain mechanisms and processes controlling the coupling between the sediments and the overlying waters. Here we used phosphate oxygen isotope ratios (δ18Op) in concert with sediment chemistry, XRD, and Mössbauer spectroscopy on the sediment retrieved from an organic rich, sulfidic site in the meso-haline portion of the mid-bay to identify sources and pathway of sedimentary P cycling and to infer potential feedback effect on bottom water hypoxia and surface water eutrophication. Isotope data indicate that the regeneration of inorganic P from organic matter degradation (remineralization) is the predominant, if not sole, pathway for authigenic P precipitation in the mid-bay sediments. We interpret that the excess inorganic P generated by remineralization should have overwhelmed any bottom-water and/or pore-water P derived from other sources or biogeochemical processes and exceeded saturation with respect to authigenic P precipitation. It is the first research that identifies the predominance of remineralization pathway against remobilization (coupled Fe-P cycling) pathway in the Chesapeake Bay. Therefore, these results are expected to have significant implications for the current understanding of P cycling and benthic-pelagic coupling in the bay, particularly on the source and pathway of P that sustains hypoxia and supports phytoplankton growth in the surface water.« less

Estimation of Land Surface Fluxes and Their Uncertainty via Variational Data Assimilation Approach

NASA Astrophysics Data System (ADS)

Abdolghafoorian, A.; Farhadi, L.

2016-12-01

Accurate estimation of land surface heat and moisture fluxes as well as root zone soil moisture is crucial in various hydrological, meteorological, and agricultural applications. "In situ" measurements of these fluxes are costly and cannot be readily scaled to large areas relevant to weather and climate studies. Therefore, there is a need for techniques to make quantitative estimates of heat and moisture fluxes using land surface state variables. In this work, we applied a novel approach based on the variational data assimilation (VDA) methodology to estimate land surface fluxes and soil moisture profile from the land surface states. This study accounts for the strong linkage between terrestrial water and energy cycles by coupling the dual source energy balance equation with the water balance equation through the mass flux of evapotranspiration (ET). Heat diffusion and moisture diffusion into the column of soil are adjoined to the cost function as constraints. This coupling results in more accurate prediction of land surface heat and moisture fluxes and consequently soil moisture at multiple depths with high temporal frequency as required in many hydrological, environmental and agricultural applications. One of the key limitations of VDA technique is its tendency to be ill-posed, meaning that a continuum of possibilities exists for different parameters that produce essentially identical measurement-model misfit errors. On the other hand, the value of heat and moisture flux estimation to decision-making processes is limited if reasonable estimates of the corresponding uncertainty are not provided. In order to address these issues, in this research uncertainty analysis will be performed to estimate the uncertainty of retrieved fluxes and root zone soil moisture. The assimilation algorithm is tested with a series of experiments using a synthetic data set generated by the simultaneous heat and water (SHAW) model. We demonstrate the VDA performance by comparing the (synthetic) true measurements (including profile of soil moisture and temperature, land surface water and heat fluxes, and root water uptake) with VDA estimates. In addition, the feasibility of extending the proposed approach to use remote sensing observations is tested by limiting the number of LST observations and soil moisture observations.

Modeling and Observational Framework for Diagnosing Local Land-Atmosphere Coupling on Diurnal Time Scales

NASA Technical Reports Server (NTRS)

Santanello, Joseph A., Jr.; Peters-Lidard, Christa D.; Kumar, Sujay V.; Alonge, Charles; Tao, Wei-Kuo

2009-01-01

Land-atmosphere interactions play a critical role in determining the diurnal evolution of both planetary boundary layer (PBL) and land surface temperature and moisture states. The degree of coupling between the land surface and PBL in numerical weather prediction and climate models remains largely unexplored and undiagnosed due to the complex interactions and feedbacks present across a range of scales. Further, uncoupled systems or experiments (e.g., the Project for Intercomparison of Land Parameterization Schemes, PILPS) may lead to inaccurate water and energy cycle process understanding by neglecting feedback processes such as PBL-top entrainment. In this study, a framework for diagnosing local land-atmosphere coupling is presented using a coupled mesoscale model with a suite of PBL and land surface model (LSM) options along with observations during field experiments in the U. S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to the Land Information System (LIS), which provides a flexible and high-resolution representation and initialization of land surface physics and states. Within this framework, the coupling established by each pairing of the available PBL schemes in WRF with the LSMs in LIS is evaluated in terms of the diurnal temperature and humidity evolution in the mixed layer. The co-evolution of these variables and the convective PBL is sensitive to and, in fact, integrative of the dominant processes that govern the PBL budget, which are synthesized through the use of mixing diagrams. Results show how the sensitivity of land-atmosphere interactions to the specific choice of PBL scheme and LSM varies across surface moisture regimes and can be quantified and evaluated against observations. As such, this methodology provides a potential pathway to study factors controlling local land-atmosphere coupling (LoCo) using the LIS-WRF system, which will serve as a testbed for future experiments to evaluate coupling diagnostics within the community.

Insights on the energy-water nexus through modeling of the integrated water cycle

NASA Astrophysics Data System (ADS)

Leung, L. R.; Li, H. Y.; Zhang, X.; Wan, W.; Voisin, N.; Leng, G.

2016-12-01

For sustainable energy planning, understanding the impacts of climate change, land use change, and water management is essential as they all exert notable controls on streamflow and stream temperature that influence energy production. An integrated water model representing river processes, irrigation water use and water management has been developed and coupled to a land surface model to investigate the energy-water nexus. Simulations driven by two climate change projections with the RCP 4.5 and RCP 8.5 emissions scenarios, with and without water management, are analyzed to evaluate the individual and combined effects of climate change and water management on streamflow and stream temperature. The simulations revealed important impacts of climate change and water management on both floods and droughts. The simulations also revealed the dynamics of competition between changes in water demand and water availability in the climate mitigation (RCP 4.5) and business as usual (RCP 8.5) scenarios that influence streamflow and stream temperature, with important consequences to energy production. The integrated water model is being implemented to the Accelerated Climate Modeling for Energy (ACME) to enable investigation of the energy-water nexus in the fully coupled Earth system.

Relationships between groundwater, surface water, and soil salinity in Polder 32, Southwest Bangladesh

NASA Astrophysics Data System (ADS)

Fry, D. C.; Ayers, J. C.

2014-12-01

In the coastal areas of Southwest Bangladesh polders are surrounded by tidal channels filled with brackish water. In the wet season, farmers create openings in the embankments to irrigate rice paddies. In the dry season, farmers do the same to create saline shrimp ponds. Residents on Polder 32, located within the Ganges-Brahmaputra-Meghna delta system, practice these seasonal farming techniques. Soils in the area are entisols, being sediment recently deposited, and contain mostly silt-sized particles. Brackish water in brine shrimp ponds may deposit salt in the soil, causing soil salinization. However, saline connate groundwater could also be contributing to soil salinization. Groundwater, surface water (fresh water pond, rice paddy and tidal channel water) and soil samples have been analyzed via inductively coupled plasma optical emission spectroscopy, inductively coupled plasma mass spectroscopy and ion chromatography in an attempt to correlate salinity measurements with each other in order to determine major sources of soil salinity. Multiple parameters, including distances of samples from tidal channels, inland streams, shrimp ponds and tube wells were measured to see if spatial correlations exist. Similarly, values from wet and dry seasons were compared to quantify temporal variations. Salt content in many soil samples were found to be high enough to significantly decrease rice yields. Continued soil salinization can decrease these yields even more, leading to farmers not producing enough food to sustain their families.

Atmospheric water budget over the South Asian summer monsoon region

NASA Astrophysics Data System (ADS)

Unnikrishnan, C. K.; Rajeevan, M.

2018-04-01

High resolution hybrid atmospheric water budget over the South Asian monsoon region is examined. The regional characteristics, variability, regional controlling factors and the interrelations of the atmospheric water budget components are investigated. The surface evapotranspiration was created using the High Resolution Land Data Assimilation System (HRLDAS) with the satellite-observed rainfall and vegetation fraction. HRLDAS evapotranspiration shows significant similarity with in situ observations and MODIS satellite-observed evapotranspiration. Result highlights the fundamental importance of evapotranspiration over northwest and southeast India on atmospheric water balance. The investigation shows that the surface net radiation controls the annual evapotranspiration over those regions, where the surface evapotranspiration is lower than 550 mm. The rainfall and evapotranspiration show a linear relation over the low-rainfall regions (<500 mm/year). Similar result is observed in in NASA GLDAS data (1980-2014). The atmospheric water budget shows annual, seasonal, and intra-seasonal variations. Evapotranspiration does not show a high intra-seasonal variability as compared to other water budget components. The coupling among the water budget anomalies is investigated. The results show that regional inter-annual evapotranspiration anomalies are not exactly in phase with rainfall anomalies; it is strongly influenced by the surface conditions and other atmospheric forcing (like surface net radiation). The lead and lag correlation of water budget components show that the water budget anomalies are interrelated in the monsoon season even up to 4 months lead. These results show the important regional interrelation of water budget anomalies on south Asian monsoon.

Novel insights into the mechanism of the ortho/para spin conversion of hydrogen pairs: implications for catalysis and interstellar water.

PubMed

Limbach, Hans-Heinrich; Buntkowsky, Gerd; Matthes, Jochen; Gründemann, Stefan; Pery, Tal; Walaszek, Bernadeta; Chaudret, Bruno

2006-03-13

The phenomenon of exchange coupling is taken into account in the description of the magnetic nuclear spin conversion between bound ortho- and para-dihydrogen. This conversion occurs without bond breaking, in contrast to the chemical spin conversion. It is shown that the exchange coupling needs to be reduced so that the corresponding exchange barrier can increase and the given magnetic interaction can effectively induce a spin conversion. The implications for related molecules such as water are discussed. For ice, a dipolar magnetic conversion and for liquid water a chemical conversion are predicted to occur within the millisecond timescale. It follows that a separation of water into its spin isomers, as proposed by Tikhonov and Volkov (Science 2002, 296, 2363), is not feasible. Nuclear spin temperatures of water vapor in comets, which are smaller than the gas-phase equilibrium temperatures, are proposed to be diagnostic for the temperature of the ice or the dust surface from which the water was released.

The Southern Ocean in the Coupled Model Intercomparison Project phase 5

PubMed Central

Meijers, A. J. S.

2014-01-01

The Southern Ocean is an important part of the global climate system, but its complex coupled nature makes both its present state and its response to projected future climate forcing difficult to model. Clear trends in wind, sea-ice extent and ocean properties emerged from multi-model intercomparison in the Coupled Model Intercomparison Project phase 3 (CMIP3). Here, we review recent analyses of the historical and projected wind, sea ice, circulation and bulk properties of the Southern Ocean in the updated Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble. Improvements to the models include higher resolutions, more complex and better-tuned parametrizations of ocean mixing, and improved biogeochemical cycles and atmospheric chemistry. CMIP5 largely reproduces the findings of CMIP3, but with smaller inter-model spreads and biases. By the end of the twenty-first century, mid-latitude wind stresses increase and shift polewards. All water masses warm, and intermediate waters freshen, while bottom waters increase in salinity. Surface mixed layers shallow, warm and freshen, whereas sea ice decreases. The upper overturning circulation intensifies, whereas bottom water formation is reduced. Significant disagreement exists between models for the response of the Antarctic Circumpolar Current strength, for reasons that are as yet unclear. PMID:24891395

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

PubMed Central

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

2013-01-01

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.

PubMed

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

2013-05-28

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

Coupled atmosphere-biophysics-hydrology models for environmental modeling

USGS Publications Warehouse

Walko, R.L.; Band, L.E.; Baron, Jill S.; Kittel, T.G.F.; Lammers, R.; Lee, T.J.; Ojima, D.; Pielke, R.A.; Taylor, C.; Tague, C.; Tremback, C.J.; Vidale, P.L.

2000-01-01

The formulation and implementation of LEAF-2, the Land Ecosystem–Atmosphere Feedback model, which comprises the representation of land–surface processes in the Regional Atmospheric Modeling System (RAMS), is described. LEAF-2 is a prognostic model for the temperature and water content of soil, snow cover, vegetation, and canopy air, and includes turbulent and radiative exchanges between these components and with the atmosphere. Subdivision of a RAMS surface grid cell into multiple areas of distinct land-use types is allowed, with each subgrid area, or patch, containing its own LEAF-2 model, and each patch interacts with the overlying atmospheric column with a weight proportional to its fractional area in the grid cell. A description is also given of TOPMODEL, a land hydrology model that represents surface and subsurface downslope lateral transport of groundwater. Details of the incorporation of a modified form of TOPMODEL into LEAF-2 are presented. Sensitivity tests of the coupled system are presented that demonstrate the potential importance of the patch representation and of lateral water transport in idealized model simulations. Independent studies that have applied LEAF-2 and verified its performance against observational data are cited. Linkage of RAMS and TOPMODEL through LEAF-2 creates a modeling system that can be used to explore the coupled atmosphere–biophysical–hydrologic response to altered climate forcing at local watershed and regional basin scales.

Land and atmosphere interactions using satellite remote sensing and a coupled mesoscale/land surface model

NASA Astrophysics Data System (ADS)

Hong, Seungbum

Land and atmosphere interactions have long been recognized for playing a key role in climate and weather modeling. However their quantification has been challenging due to the complex nature of the land surface amongst various other reasons. One of the difficult parts in the quantification is the effect of vegetation which are related to land surface processes such soil moisture variation and to atmospheric conditions such as radiation. This study addresses various relational investigations among vegetation properties such as Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), surface temperature (TSK), and vegetation water content (VegWC) derived from satellite sensors such as Moderate Resolution Imaging Spectroradiometer (MODIS) and EOS Advanced Microwave Scanning Radiometer (AMSR-E). The study provides general information about a physiological behavior of vegetation for various environmental conditions. Second, using a coupled mesoscale/land surface model, we examined the effects of vegetation and its relationship with soil moisture on the simulated land-atmospheric interactions through the model sensitivity tests. The Weather Research and Forecasting (WRF) model was selected for this study, and the Noah land surface model (Noah LSM) implemented in the WRF model was used for the model coupled system. This coupled model was tested through two parameterization methods for vegetation fraction using MODIS data and through model initialization of soil moisture from High Resolution Land Data Assimilation System (HRLDAS). Then, this study evaluates the model improvements for each simulation method.

An integrated crop and hydrologic modeling system to estimate hydrologic impacts of crop irrigation demands

Treesearch

R.T. McNider; C. Handyside; K. Doty; W.L. Ellenburg; J.F. Cruise; J.R. Christy; D. Moss; V. Sharda; G. Hoogenboom; Peter Caldwell

2015-01-01

The present paper discusses a coupled gridded crop modeling and hydrologic modeling system that can examine the benefits of irrigation and costs of irrigation and the coincident impact of the irrigation water withdrawals on surface water hydrology. The system is applied to the Southeastern U.S. The system tools to be discussed include a gridded version (GriDSSAT) of...

An ecological mechanism to create regular patterns of surface dissolution in a low-relief carbonate landscape

NASA Astrophysics Data System (ADS)

Cohen, M. J.; Martin, J. B.; Mclaughlin, D. L.; Osborne, T.; Murray, A.; Watts, A. C.; Watts, D.; Heffernan, J. B.

2012-12-01

Development of karst landscapes is controlled by focused delivery of water undersaturated with respect to the soluble rock minerals. As that water comes to equilibrium with the rock, secondary porosity is incrementally reinforced creating a positive feedback that acts to augment the drainage network and subsequent water delivery. In most self-organizing systems, spatial positive feedbacks create features (in landscapes: patches; in karst aquifers: conduits) whose size-frequency relationship follows a power function, indicating a higher probability of large features than would occur with a random or Gaussian genesis process. Power functions describe several aspects of secondary porosity in the Upper Floridan Aquifer in north Florida. In contrast, a different pattern arises in the karst landscape in southwest Florida (Big Cypress National Preserve; BICY), where low-relief and a shallow aquiclude govern regional hydrology. There, the landscape pattern is highly regular (Fig. 1), with circular cypress-dominated wetlands occupying depressions that are hydrologically isolated and distributed evenly in a matrix of pine uplands. Regular landscape patterning results from spatially coupled feedbacks, one positive operating locally that expands patches coupled to another negative that operates at distance, eventually inhibiting patch expansion. The positive feedback in BICY is thought to derive from the presence of surface depressions, which sustain prolonged inundation in this low-relief setting, and facilitate wetland development that greatly augments dissolution potential of infiltrating water in response to ecosystem metabolic processes. In short, wetlands "drill" into the carbonate leading to both vertical and lateral basin expansion. Wetland expansion occurs at the expense of surrounding upland area, which is the local catchment that subsidizes water availability. A distal inhibitory feedback on basin expansion thus occurs as the water necessary to sustain prolonged inundation becomes limiting. The implied strong reciprocal coupling between surface production of organic matter and patterns of induced subsurface carbonate dissolution are a novel example of co-evolving biogeomorphic processes in the earth system. Fig. 1 - Regular patterned landscape in Big Cypress National Preserve showing cypress dominated wetlands (round features) embedded in a mosaic of pine and grass uplands. Exposed carbonate rings are evident at the margins of many of the wetland basins.

The Arsenic crisis in Bangladesh (Invited)

NASA Astrophysics Data System (ADS)

Harvey, C.; Ashfaque, K.; Neumann, R. B.; Badruzzaman, B.; Ali, A.

2010-12-01

The Ganges Delta suffers from water-borne disease. Arsenic in the groundwater pumped from drinking water wells is causing severe and widespread disease, and these wells were installed, in part, to avoid pathogens in the surface water supply. I will discuss the hydrogeologic controls of arsenic concentrations in groundwater, specifically the role of enhanced groundwater circulation driven by irrigation pumping and the effects of the solute loads transported into aquifers with recharge through different surface features, such as rice fields, rivers, and ponds. I will contrast the approaches taken in Southeast Asia for studying groundwater contamination with methods used in the U.S. I will compare findings from several sites in the region and consider how improved models of the coupled hydrologic and biogeochemical system can be used to provide safer water.

Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans

DOE PAGES

Park, Dae Sung; Joseph, Kristeen E.; Koehle, Maura; ...

2016-10-19

One important advance in fluid surface control was the amphiphilic surfactant composed of coupled molecular structures (i.e., hydrophilic and hydrophobic) to reduce surface tension between two distinct fluid phases. However, implementation of simple surfactants has been hindered by the broad range of applications in water containing alkaline earth metals (i.e., hard water). This disrupts surfactant function and requires extensive use of undesirable and expensive chelating additives. We show that sugar-derived furans can be linked with triglyceride-derived fatty acid chains via Friedel–Crafts acylation within single layer (SPP) zeolite catalysts. Finally, these alkylfuran surfactants independently suppress the effects of hard water whilemore » simultaneously permitting broad tunability of size, structure, and function, which can be optimized for superior capability for forming micelles and solubilizing in water.« less

Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Dae Sung; Joseph, Kristeen E.; Koehle, Maura

2016-11-23

An important advance in fluid surface control was the amphiphilic surfactant comprised of coupled molecular structures (i.e. hydrophilic and hydrophobic) to reduce surface tension between two distinct fluid phases. However, implementation of simple surfactants has been hindered by the broad range of applications in water containing alkaline earth metals (i.e. hard water), which disrupt surfactant function and require extensive use of undesirable and expensive chelating additives. Here we show that sugar-derived furans can be linked with triglyceride-derived fatty acid chains via Friedel-Crafts acylation within single layer (SPP) zeolite catalysts. These alkylfuran surfactants independently suppress the effects of hard water whilemore » simultaneously permitting broad tunability of size, structure, and function, which can be optimized for superior capability for forming micelles and solubilizing in water.« less

Determination of the Presence of Three Antimicrobials in Surface Water Collected from Urban and Rural Areas

PubMed Central

Iglesias, Alejandra; Nebot, Carolina; Miranda, Jose M.; Vázquez, Beatriz I.; Abuín, Carlos M. Franco; Cepeda, Alberto

2013-01-01

Due to the continuous release of antimicrobials into the environment, the aim of this study was to compare the frequency of detection of sulfamethazine, sulfamethoxypyridazine and trimethoprim in surface water collected from urban and rural areas in Northwestern Spain. A monitoring study was conducted with 314 river water samples analyzed by high-performance liquid chromatography coupled to tandem mass spectrometry. The results indicated that 37% of the samples contained residues of at least one of the investigated antimicrobials, and every sampling site yielded positive samples. At sites located near the discharge points of wastewater treatment plants and near the collection point of a drinking-water treatment plant, more than 6% of the samples were positive for the presence of antimicrobial residues. PMID:27029291

A global, 30-m resolution land-surface water body dataset for 2000

NASA Astrophysics Data System (ADS)

Feng, M.; Sexton, J. O.; Huang, C.; Song, D. X.; Song, X. P.; Channan, S.; Townshend, J. R.

2014-12-01

Inland surface water is essential to terrestrial ecosystems and human civilization. The distribution of surface water in space and its change over time are related to many agricultural, environmental and ecological issues, and are important factors that must be considered in human socioeconomic development. Accurate mapping of surface water is essential for both scientific research and policy-driven applications. Satellite-based remote sensing provides snapshots of Earth's surface and can be used as the main input for water mapping, especially in large areas. Global water areas have been mapped with coarse resolution remotely sensed data (e.g., the Moderate Resolution Imaging Spectroradiometer (MODIS)). However, most inland rivers and water bodies, as well as their changes, are too small to map at such coarse resolutions. Landsat TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) imagery has a 30m spatial resolution and provides decades of records (~40 years). Since 2008, the opening of the Landsat archive, coupled with relatively lower costs associated with computing and data storage, has made comprehensive study of the dynamic changes of surface water over large even global areas more feasible. Although Landsat images have been used for regional and even global water mapping, the method can hardly be automated due to the difficulties on distinguishing inland surface water with variant degrees of impurities and mixing of soil background with only Landsat data. The spectral similarities to other land cover types, e.g., shadow and glacier remnants, also cause misidentification. We have developed a probabilistic based automatic approach for mapping inland surface water bodies. Landsat surface reflectance in multiple bands, derived water indices, and data from other sources are integrated to maximize the ability of identifying water without human interference. The approach has been implemented with open-source libraries to facilitate processing large amounts of Landsat images on high-performance computing machines. It has been applied to the ~9,000 Landsat scenes of the Global Land Survey (GLS) 2000 data collection to produce a global, 30m resolution inland surface water body data set, which will be made available on the Global Land Cover Facility (GLCF) website (http://www.landcover.org).

Global Precipitation Measurement (GPM) Ground Validation (GV) Science Implementation Plan

NASA Technical Reports Server (NTRS)

Petersen, Walter A.; Hou, Arthur Y.

2008-01-01

For pre-launch algorithm development and post-launch product evaluation Global Precipitation Measurement (GPM) Ground Validation (GV) goes beyond direct comparisons of surface rain rates between ground and satellite measurements to provide the means for improving retrieval algorithms and model applications.Three approaches to GPM GV include direct statistical validation (at the surface), precipitation physics validation (in a vertical columns), and integrated science validation (4-dimensional). These three approaches support five themes: core satellite error characterization; constellation satellites validation; development of physical models of snow, cloud water, and mixed phase; development of cloud-resolving model (CRM) and land-surface models to bridge observations and algorithms; and, development of coupled CRM-land surface modeling for basin-scale water budget studies and natural hazard prediction. This presentation describes the implementation of these approaches.

Near-surface turbulence as a missing link in modeling evapotranspiration-soil moisture relationships

NASA Astrophysics Data System (ADS)

Haghighi, Erfan; Kirchner, James W.

2017-07-01

Despite many efforts to develop evapotranspiration (ET) models with improved parametrizations of resistance terms for water vapor transfer into the atmosphere, estimates of ET and its partitioning remain prone to bias. Much of this bias could arise from inadequate representations of physical interactions near nonuniform surfaces from which localized heat and water vapor fluxes emanate. This study aims to provide a mechanistic bridge from land-surface characteristics to vertical transport predictions, and proposes a new physically based ET model that builds on a recently developed bluff-rough bare soil evaporation model incorporating coupled soil moisture-atmospheric controls. The newly developed ET model explicitly accounts for (1) near-surface turbulent interactions affecting soil drying and (2) soil-moisture-dependent stomatal responses to atmospheric evaporative demand that influence leaf (and canopy) transpiration. Model estimates of ET and its partitioning were in good agreement with available field-scale data, and highlight hidden processes not accounted for by commonly used ET schemes. One such process, nonlinear vegetation-induced turbulence (as a function of vegetation stature and cover fraction) significantly influences ET-soil moisture relationships. Our results are particularly important for water resources and land use planning of semiarid sparsely vegetated ecosystems where soil surface interactions are known to play a critical role in land-climate interactions. This study potentially facilitates a mathematically tractable description of the strength (i.e., the slope) of the ET-soil moisture relationship, which is a core component of models that seek to predict land-atmosphere coupling and its feedback to the climate system in a changing climate.

Exploiting Soil Moisture, Precipitation, and Streamflow Observations to Evaluate Soil Moisture/Runoff Coupling in Land Surface Models

NASA Astrophysics Data System (ADS)

Crow, W. T.; Chen, F.; Reichle, R. H.; Xia, Y.; Liu, Q.

2018-05-01

Accurate partitioning of precipitation into infiltration and runoff is a fundamental objective of land surface models tasked with characterizing the surface water and energy balance. Temporal variability in this partitioning is due, in part, to changes in prestorm soil moisture, which determine soil infiltration capacity and unsaturated storage. Utilizing the National Aeronautics and Space Administration Soil Moisture Active Passive Level-4 soil moisture product in combination with streamflow and precipitation observations, we demonstrate that land surface models (LSMs) generally underestimate the strength of the positive rank correlation between prestorm soil moisture and event runoff coefficients (i.e., the fraction of rainfall accumulation volume converted into stormflow runoff during a storm event). Underestimation is largest for LSMs employing an infiltration-excess approach for stormflow runoff generation. More accurate coupling strength is found in LSMs that explicitly represent subsurface stormflow or saturation-excess runoff generation processes.

Modeling CO2 degassing and pH in a stream-aquifer system

USGS Publications Warehouse

Choi, J.; Hulseapple, S.M.; Conklin, M.H.; Harvey, J.W.

1998-01-01

Pinal Creek, Arizona receives an inflow of ground water with high dissolved inorganic carbon (57-75 mg/l) and low pH (5.8-6.3). There is an observed increase of in-stream pH from approximately 6.0-7.8 over the 3 km downstream of the point of groundwater inflow. We hypothesized that CO2 gas-exchange was the most important factor causing the pH increase in this stream-aquifer system. An existing transport model, for coupled ground water-surface water systems (OTIS), was modified to include carbonate equilibria and CO2 degassing, used to simulate alkalinity, total dissolved inorganic carbon (C(T)), and pH in Pinal Creek. Because of the non-linear relation between pH and C(T), the modified transport model used the numerical iteration method to solve the non-linearity. The transport model parameters were determined by the injection of two tracers, bromide and propane. The resulting simulations of alkalinity, C(T) and pH reproduced, without fitting, the overall trends in downstream concentrations. A multi-parametric sensitivity analysis (MPSA) was used to identify the relative sensitivities of the predictions to six of the physical and chemical parameters used in the transport model. MPSA results implied that C(T) and pH in stream water were controlled by the mixing of ground water with stream water and CO2 degassing. The relative importance of these two processes varied spatially depending on the hydrologic conditions, such as stream flow velocity and whether a reach gained or lost stream water caused by the interaction with the ground water. The coupled transport model with CO2 degassing and generalized sensitivity analysis presented in this study can be applied to evaluate carbon transport and pH in other coupled stream-ground water systems.An existing transport model for coupled groundwater-surface water systems was modified to include carbonate equilibria and CO2 degassing. The modified model was used to simulate alkalinity, total dissolved inorganic carbon (CT) and pH in Pinal Creek. The model used the numerical iteration method to solve the nonlinear relation between pH and CT. A multi-parametric sensitivity analysis (MPSA) was used to identify the relative sensitivities of the predictions to six of the physical and chemical parameters used in the transport model. MPSA results implied that CT and pH in the stream water were controlled by the mixing of groundwater with stream water and CO2 degassing.

Surface and microstructure modifications of Ti-6Al-4V titanium alloy cutting by a water jet/high power laser converging coupling

NASA Astrophysics Data System (ADS)

Weiss, Laurent; Tazibt, Abdel; Aillerie, Michel; Tidu, Albert

2018-01-01

The metallurgical evolution of the Ti-6Al-4V samples is analyzed after an appropriate cutting using a converging water jet/high power laser system. New surface microstructures are obtained on the cutting edge as a result of thermo-mechanical effects of such hybrid fluid-jet-laser tool on the targeted material. The laser beam allows to melt and the water-jet to cool down and to evacuate the material upstream according to a controlled cutting process. The experimental results have shown that a rutile layer can be generated on the surface near the cutting zone. The recorded metallurgical effect is attributed to the chemical reaction between water molecules and titanium, where the laser thermal energy brought onto the surface plays the role of reaction activator. The width of the oxidized zone was found proportional to the cutting speed. During the reaction, hydrogen gas H2 is formed and is absorbed by the metal. The hydrogen atoms trapped into the alloy change the metastable phase formation developing pure β circular grains as a skin at the kerf surface. This result is original so it would lead to innovative converging laser water jet process that could be used to increase the material properties especially for surface treatment, a key value of surface engineering and manufacturing chains.

Coupled Spatiotemporal Dynamics of Microbial Community Ecology, Biogeochemistry, and Hydrologic Mixing

NASA Astrophysics Data System (ADS)

Stegen, J.; Johnson, T. C.; Fredrickson, J.; Wilkins, M.; Konopka, A.; Nelson, W.; Arntzen, E.; Chrisler, W.; Chu, R. K.; Fansler, S.; Kennedy, D.; Resch, T.; Tfaily, M. M.

2015-12-01

The hyporheic zone (HZ) is a critical ecosystem component that links terrestrial, surface water, and groundwater ecosystems. A dominant feature of the HZ is groundwater-surface water mixing and the input of terrestrially—as well as aquatically—derived organic carbon. In many systems the HZ has a relatively small spatial extent, but in larger riverine systems groundwater-surface water mixing can occur 100s of meters beyond the surface water shoreline; we consider these more distal locations to be within the 'subsurface interaction zone' (SIZ) as they are beyond the traditional HZ. Microbial communities in the HZ and SIZ drive biogeochemical processes in these system components, yet relatively little is known about the ecological processes that drive HZ and SIZ microbial communities. Here, we applied ecological theory, aqueous biogeochemistry, DNA sequencing, and ultra-high resolution organic carbon profiling to field samples collected through space (400m spatial extent) and time (7 month temporal extent) within the Hanford Site 300 Area. These data streams were integrated to evaluate how the influence of groundwater-surface water mixing on microbial communities changes when moving from the HZ to the broader SIZ. Our results indicate that groundwater-surface water mixing (i) consistently stimulated heterotrophic respiration, but only above a threshold of surface water intrusion, (ii) did not stimulate denitrification, (iii) caused deterministic shifts in HZ microbial communities due to changes in organic carbon composition, and (iv) did not cause shifts in SIZ microbial communities. These results suggest that microbial communities and the biogeochemical processes they drive are impacted by groundwater-surface water mixing primarily in the HZ and to a lesser extent in the SIZ.

An Eulerian two-phase flow model for sediment transport under realistic surface waves

NASA Astrophysics Data System (ADS)

Hsu, T. J.; Kim, Y.; Cheng, Z.; Chauchat, J.

2017-12-01

Wave-driven sediment transport is of major importance in driving beach morphology. However, the complex mechanisms associated with unsteadiness, free-surface effects, and wave-breaking turbulence have not been fully understood. Particularly, most existing models for sediment transport adopt bottom boundary layer approximation that mimics the flow condition in oscillating water tunnel (U-tube). However, it is well-known that there are key differences in sediment transport when comparing to large wave flume datasets, although the number of wave flume experiments are relatively limited regardless of its importance. Thus, a numerical model which can resolve the entire water column from the bottom boundary layer to the free surface can be a powerful tool. This study reports an on-going effort to better understand and quantify sediment transport under shoaling and breaking surface waves through the creation of open-source numerical models in the OpenFOAM framework. An Eulerian two-phase flow model, SedFoam (Cheng et al., 2017, Coastal Eng.) is fully coupled with a volume-of-fluid solver, interFoam/waves2Foam (Jacobsen et al., 2011, Int. J. Num. Fluid). The fully coupled model, named SedWaveFoam, regards the air and water phases as two immiscible fluids with the interfaces evolution resolved, and the sediment particles as dispersed phase. We carried out model-data comparisons with the large wave flume sheet flow data for nonbreaking waves reported by Dohmen-Janssen and Hanes (2002, J. Geophysical Res.) and good agreements were obtained for sediment concentration and net transport rate. By further simulating a case without free-surface (mimic U-tube condition), the effects of free-surface, most notably the boundary layer streaming effect on total transport, can be quantified.

Integrating peatlands into the coupled Canadian Land Surface Scheme (CLASS) v3.6 and the Canadian Terrestrial Ecosystem Model (CTEM) v2.0

NASA Astrophysics Data System (ADS)

Wu, Yuanqiao; Verseghy, Diana L.; Melton, Joe R.

2016-08-01

Peatlands, which contain large carbon stocks that must be accounted for in the global carbon budget, are poorly represented in many earth system models. We integrated peatlands into the coupled Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM), which together simulate the fluxes of water, energy, and CO2 at the land surface-atmosphere boundary in the family of Canadian Earth system models (CanESMs). New components and algorithms were added to represent the unique features of peatlands, such as their characteristic ground floor vegetation (mosses), the slow decomposition of carbon in the water-logged soils and the interaction between the water, energy, and carbon cycles. This paper presents the modifications introduced into the CLASS-CTEM modelling framework together with site-level evaluations of the model performance for simulated water, energy and carbon fluxes at eight different peatland sites. The simulated daily gross primary production (GPP) and ecosystem respiration are well correlated with observations, with values of the Pearson correlation coefficient higher than 0.8 and 0.75 respectively. The simulated mean annual net ecosystem production at the eight test sites is 87 g C m-2 yr-1, which is 22 g C m-2 yr-1 higher than the observed annual mean. The general peatland model compares well with other site-level and regional-level models for peatlands, and is able to represent bogs and fens under a range of climatic and geographical conditions.

Integrating peatlands into the coupled Canadian Land Surface Scheme (CLASS) v3.6 and the Canadian Terrestrial Ecosystem Model (CTEM) v2.0

NASA Astrophysics Data System (ADS)

Wu, Y.; Verseghy, D. L.; Melton, J. R.

2015-11-01

Peatlands, which contain large carbon stocks that must be accounted for in the global carbon budget, are poorly represented in many earth system models. We integrated peatlands into the coupled Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM), which together simulate the fluxes of water, energy and CO2 at the land surface-atmosphere boundary in the family of Canadian Earth System Models (CanESMs). New components and algorithms were added to represent the unique features of peatlands, such as their characteristic ground floor vegetation (mosses), the slow decomposition of carbon in the water-logged soils and the interaction between the water, energy and carbon cycles. This paper presents the modifications introduced into the CLASS-CTEM modelling framework together with site-level evaluations of the model performance for simulated water, energy and carbon fluxes at eight different peatland sites. The simulated daily gross primary production and ecosystem respiration are well correlated with observations, with values of the Pearson correlation coefficient higher than 0.8 and 0.75 respectively. The simulated mean annual net ecosystem production at the eight test sites is 87 g C m-2 yr-1, which is 22 g C m-2 yr-1 higher than the observed annual mean. The general peatland model compares well with other site-level and regional-level models for peatlands, and is able to represent bogs and fens under a range of climatic and geographical conditions.

Physically Accurate Soil Freeze-Thaw Processes in a Global Land Surface Scheme

NASA Astrophysics Data System (ADS)

Cuntz, Matthias; Haverd, Vanessa

2018-01-01

The model Soil-Litter-Iso (SLI) calculates coupled heat and water transport in soil. It was recently implemented into the Australian land surface model CABLE, which is the land component of the Australian Community Climate and Earth System Simulator (ACCESS). Here we extended SLI to include accurate freeze-thaw processes in the soil and snow. SLI provides thence an implicit solution of the energy and water balances of soil and snow as a standalone model and within CABLE. The enhanced SLI was tested extensively against theoretical formulations, laboratory experiments, field data, and satellite retrievals. The model performed well for all experiments at wide-ranging temporal and spatial scales. SLI melts snow faster at the end of the cold season compared to observations though because there is no subgrid variability within SLI given by the implicit, coupled solution of energy and water. Combined CABLE-SLI shows very realistic dynamics and extent of permafrost on the Northern hemisphere. It illustrated, however, also the limits of possible comparisons between large-scale land surface models and local permafrost observations. CABLE-SLI exhibits the same patterns of snow depth and snow water equivalent on the Northern hemisphere compared to satellite-derived observations but quantitative comparisons depend largely on the given meteorological input fields. Further extension of CABLE-SLI with depth-dependence of soil carbon will allow realistic projections of the development of permafrost and frozen carbon stocks in a changing climate.

Vibrational spectroscopic study of pH dependent solvation at a Ge(100)-water interface during an electrode potential triggered surface termination transition

NASA Astrophysics Data System (ADS)

Niu, Fang; Rabe, Martin; Nayak, Simantini; Erbe, Andreas

2018-06-01

The charge-dependent structure of interfacial water at the n-Ge(100)-aqueous perchlorate interface was studied by controlling the electrode potential. Specifically, a joint attenuated total reflection infrared spectroscopy and electrochemical experiment was used in 0.1M NaClO4 at pH ≈ 1-10. The germanium surface transformation to an H-terminated surface followed the thermodynamic Nernstian pH dependence and was observed throughout the entire pH range. A singular value decomposition-based spectra deconvolution technique coupled to a sigmoidal transition model for the potential dependence of the main components in the spectra shows the surface transformation to be a two-stage process. The first stage was observed together with the first appearance of Ge-H stretching modes in the spectra and is attributed to the formation of a mixed surface termination. This transition was reversible. The second stage occurs at potentials ≈0.1-0.3 V negative of the first one, shows a hysteresis in potential, and is attributed to the formation of a surface with maximum Ge-H coverage. During the surface transformation, the surface becomes hydrophobic, and an effective desolvation layer, a "hydrophobic gap," developed with a thickness ≈1-3 Å. The largest thickness was observed near neutral pH. Interfacial water IR spectra show a loss of strongly hydrogen-bound water molecules compared to bulk water after the surface transformation, and the appearance of "free," non-hydrogen bound OH groups, throughout the entire pH range. Near neutral pH at negative electrode potentials, large changes at wavenumbers below 1000 cm-1 were observed. Librational modes of water contribute to the observed changes, indicating large changes in the water structure.

Integrated water flow model and modflow-farm process: A comparison of theory, approaches, and features of two integrated hydrologic models

USGS Publications Warehouse

Dogrul, Emin C.; Schmid, Wolfgang; Hanson, Randall T.; Kadir, Tariq; Chung, Francis

2016-01-01

Effective modeling of conjunctive use of surface and subsurface water resources requires simulation of land use-based root zone and surface flow processes as well as groundwater flows, streamflows, and their interactions. Recently, two computer models developed for this purpose, the Integrated Water Flow Model (IWFM) from the California Department of Water Resources and the MODFLOW with Farm Process (MF-FMP) from the US Geological Survey, have been applied to complex basins such as the Central Valley of California. As both IWFM and MFFMP are publicly available for download and can be applied to other basins, there is a need to objectively compare the main approaches and features used in both models. This paper compares the concepts, as well as the method and simulation features of each hydrologic model pertaining to groundwater, surface water, and landscape processes. The comparison is focused on the integrated simulation of water demand and supply, water use, and the flow between coupled hydrologic processes. The differences in the capabilities and features of these two models could affect the outcome and types of water resource problems that can be simulated.

Towards A Synthesis Of Land Dynamics And Hydrological Processes Across Central Asia

NASA Astrophysics Data System (ADS)

Sokolik, I. N.; Tatarskii, V.; Shiklomanov, A. I.; Henebry, G. M.; de Beurs, K.; Laruelle, M.

2016-12-01

We present results from an ongoing project that aims to synthesize land dynamics, hydrological processes, and socio-economic changes across the five countries of Central Asia. We have developed a fully coupled model that takes into account the reconstructed land cover and land use dynamics to simulate dust emissions. A comparable model has been developed to model smoke emissions from wildfires. Both models incorporate land dynamics explicitly. We also present a characterization of land surface change based on a suite of MODIS products including vegetation indices, evapotranspiration, land surface temperature, and albedo. These results are connected with ongoing land privatization reforms that different across the region. We also present a regional analysis of water resources, including the significant impact of using surface water for irrigation in an arid landscape. We applied the University of New Hampshire hydrological model to understand the consequences of changes in climate, water, and land use on regional hydrological processes and water use. Water security and its dynamic have been estimated through an analysis of multiple indices and variables characterizing the water availability and water use. The economic consequences of the water privatization processes will be presented.

Model for dynamic self-assembled magnetic surface structures

NASA Astrophysics Data System (ADS)

Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.

2010-07-01

We propose a first-principles model for the dynamic self-assembly of magnetic structures at a water-air interface reported in earlier experiments. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended at a water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snakelike structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids.

Estimating the Mean Circulation and Water Exchange of the Gulf of Suez-Red Sea via a Validated One-Way Atmospheric-Hydrodynamic Coupled Model

NASA Astrophysics Data System (ADS)

Eladawy, Ahmed; Shaltout, Mohamed; Sousa, Magda Catarina; Dias, João Miguel; Nadaoka, Kazuo

2018-05-01

The Gulf of Suez, Northern Islands protected area, and Hurghada zone are experiencing mega developments in all sectors including tourism, industry, and logistics. The need for moderately accurate near-shore hydrodynamic models is increasing to support the sustainable development of this oceanic area. This can be accomplished by following a nesting approach including the downscaling of global atmospheric and oceanic models into local models using higher resolution datasets. This work aims to present the development of a one-way coupling between atmospheric and hydrodynamic models for the Gulf of Suez (GOS) to understand the local oceanic characteristics and processes. The Regional Climate Model system (RegCM4) is used to simulate moderate resolution atmospheric features and its results are used to force a local dedicated application of Delft3D model. The results indicate that the predicted water level, water temperature, and evaporation accurately follow in situ measurements, remotely sensed data, and re-analysis data. The results suggest that the annual sea surface temperature is averaged at 23 °C, while the annual average of evaporation rates equals 8.02 mm/day. The study suggests that the water level displays a marked seasonal and spatial variation. Moreover, the water balance in the Gulf of Suez was controlled by the difference between inflows and outflows through the Straits of Gubal and by the net precipitation. In addition, the water balance indicated a net loss of approximately 3.9 × 10-3 m of water during 2013. Moreover, the exchange through the Straits of Gubal showed a two-way exchange with a net inflow of 0.0007 Sv, where the outflow dominated in the surface layer along the western coast and the inflow dominated in the lower layers along the middle of the Straits. To conclude, the one-way coupling modeling technique proved to be a reliable tool for studying local features of the GOS region.

[The polarization characteristics distribution and correction method of the polarization coupling error in ocean remote sensing system].

PubMed

Gao, Jun; Wang, Shu-Peng; Gu, Xing-Fa; Yu, Tao; Fang, Li

2012-06-01

With the development of the quantitative researches using ocean color remote sensing data sets, study on reducing the uncertainty of the response of the ocean color remote sensors to the polarization characteristics of the target has been attracting more and more attention recently. Taking MODIS as an example, the polarization distribution in the whole field of view was analyzed. For the atmosphere path radiance and the apparent radiance considering the coupling between ocean surface and atmosphere, the polarization distribution has a strong relation with the imaging geometry. Compared to the contribution of the polarization from the rough sea surface, the contribution from the atmosphere is dominated. Based on the polarization characteristics in the field of view, the influence of the polarization coupling error on the quality of the satellite data was studied with the assumption of different polarization sensitivities. It was found that errors due to polarization sensitivity in the field of view are lower than water leaving radiance only when the polarization sensitivity is less than 2%. And in this case it can meet the need of the retrieval of water leaving radiative products. The method of the compensation for the polarization coupling error due to the atmosphere is proposed, which proved to be effective to improve the utilization of satellite data and the accuracy of measured radiance by remote sensor.

Free vibration analysis of elastic structures submerged in an infinite or semi-infinite fluid domain by means of a coupled FE-BE solver

NASA Astrophysics Data System (ADS)

Zheng, Chang-Jun; Bi, Chuan-Xing; Zhang, Chuanzeng; Gao, Hai-Feng; Chen, Hai-Bo

2018-04-01

The vibration behavior of thin elastic structures can be noticeably influenced by the surrounding water, which represents a kind of heavy fluid. Since the feedback of the acoustic pressure onto the structure cannot be neglected in this case, a strong coupled scheme between the structural and fluid domains is usually required. In this work, a coupled finite element and boundary element (FE-BE) solver is developed for the free vibration analysis of structures submerged in an infinite fluid domain or a semi-infinite fluid domain with a free water surface. The structure is modeled by the finite element method (FEM). The compressibility of the fluid is taken into account, and hence the Helmholtz equation serves as the governing equation of the fluid domain. The boundary element method (BEM) is employed to model the fluid domain, and a boundary integral formulation with a half-space fundamental solution is used to satisfy the Dirichlet boundary condition on the free water surface exactly. The resulting nonlinear eigenvalue problem (NEVP) is converted into a small linear one by using a contour integral method. Adequate modifications are suggested to improve the efficiency of the contour integral method and avoid missing the eigenfrequencies of interest. The Burton-Miller method is used to filter out the fictitious eigenfrequencies of the boundary integral formulations. Numerical examples are given to demonstrate the accuracy and applicability of the developed eigensolver, and also show that the fluid-loading effect strongly depends on both the water depth and the mode shapes.

Coupling physics and biogeochemistry thanks to high-resolution observations of the phytoplankton community structure in the northwestern Mediterranean Sea

NASA Astrophysics Data System (ADS)

Marrec, Pierre; Grégori, Gérald; Doglioli, Andrea M.; Dugenne, Mathilde; Della Penna, Alice; Bhairy, Nagib; Cariou, Thierry; Hélias Nunige, Sandra; Lahbib, Soumaya; Rougier, Gilles; Wagener, Thibaut; Thyssen, Melilotus

2018-03-01

Fine-scale physical structures and ocean dynamics strongly influence and regulate biogeochemical and ecological processes. These processes are particularly challenging to describe and understand because of their ephemeral nature. The OSCAHR (Observing Submesoscale Coupling At High Resolution) campaign was conducted in fall 2015 in which a fine-scale structure (1-10 km/1-10 days) in the northwestern Mediterranean Ligurian subbasin was pre-identified using both satellite and numerical modeling data. Along the ship track, various variables were measured at the surface (temperature, salinity, chlorophyll a and nutrient concentrations) with ADCP current velocity. We also deployed a new model of the CytoSense automated flow cytometer (AFCM) optimized for small and dim cells, for near real-time characterization of the surface phytoplankton community structure of surface waters with a spatial resolution of a few kilometers and an hourly temporal resolution. For the first time with this optimized version of the AFCM, we were able to fully resolve Prochlorococcus picocyanobacteria in addition to the easily distinguishable Synechococcus. The vertical physical dynamics and biogeochemical properties of the studied area were investigated by continuous high-resolution CTD profiles thanks to a moving vessel profiler (MVP) during the vessel underway associated with a high-resolution pumping system deployed during fixed stations allowing sampling of the water column at a fine resolution (below 1 m). The observed fine-scale feature presented a cyclonic structure with a relatively cold core surrounded by warmer waters. Surface waters were totally depleted in nitrate and phosphate. In addition to the doming of the isopycnals by the cyclonic circulation, an intense wind event induced Ekman pumping. The upwelled subsurface cold nutrient-rich water fertilized surface waters and was marked by an increase in Chl a concentration. Prochlorococcus and pico- and nano-eukaryotes were more abundant in cold core waters, while Synechococcus dominated in warm boundary waters. Nanoeukaryotes were the main contributors ( > 50 %) in terms of pigment content (red fluorescence) and biomass. Biological observations based on the mean cell's red fluorescence recorded by AFCM combined with physical properties of surface waters suggest a distinct origin for two warm boundary waters. Finally, the application of a matrix growth population model based on high-frequency AFCM measurements in warm boundary surface waters provides estimates of in situ growth rate and apparent net primary production for Prochlorococcus (μ = 0.21 d-1, NPP = 0.11 mg C m-3 d-1) and Synechococcus (μ = 0.72 d-1, NPP = 2.68 mg C m-3 d-1), which corroborate their opposite surface distribution pattern. The innovative adaptive strategy applied during OSCAHR with a combination of several multidisciplinary and complementary approaches involving high-resolution in situ observations and sampling, remote-sensing and model simulations provided a deeper understanding of the marine biogeochemical dynamics through the first trophic levels.

Influence of the surface permeability on the GRACE water mass variations. Case of the Lake Chad basin.

NASA Astrophysics Data System (ADS)

Lopez, T.; Ramillien, G.; Antoine, R.; Darrozes, J.; Rabinowicz, M.

2017-12-01

Since its launch in 2002, the Gravity Recovery And Climate Experiment (GRACE) has been measured the tiny variations of the gravity field due to redistributions of water mass in the surface envelops of Earth. At a spatial resolution of 400 km, these satellite data offer a unique perspective to understand the evolution of continental water storage at regional and global scales, and therefore they enable the monitoring of the hydrological systems such as river basins. It is well known that seasonal cycle, droughts, vegetation and human extractions are the main contributors of the hydrology signals sensed by GRACE. However, the coupling between land surface and the atmosphere is important in semi-arid and arid regions, in particular in West Africa [1]. We propose to quantify the surface water fluxes in the Lake Chad region by using the 10-day water mass solutions of the GRACE mission in the context of the regular West African monsoon. Alternation of the evaporation/condensation cycles during the recent period are interpreted in terms of surface vertical permeability changes that control the thermal evolution in this region [2]. GRACE solutions reveal an interannual increase of surface water mass at the beginning of the dry seasons, especially between 2005 and 2008. We propose that this gain of surface water mass is caused by a seasonal cycle of clay fracturing that controls the evaporation/condensation cycle. [1] Koster et al. (2004). Science, 305, 1138-1140. [2] Lopez et al. (2016). Surv. Geophys., 37 (2), 471-502.

Integration of nitrogen dynamics into the Noah-MP land surface model v1.1 for climate and environmental predictions

DOE PAGES

Cai, X.; Yang, Z. -L.; Fisher, J. B.; ...

2016-01-15

Climate and terrestrial biosphere models consider nitrogen an important factor in limiting plant carbon uptake, while operational environmental models view nitrogen as the leading pollutant causing eutrophication in water bodies. The community Noah land surface model with multi-parameterization options (Noah-MP) is unique in that it is the next-generation land surface model for the Weather Research and Forecasting meteorological model and for the operational weather/climate models in the National Centers for Environmental Prediction. Here in this study, we add a capability to Noah-MP to simulate nitrogen dynamics by coupling the Fixation and Uptake of Nitrogen (FUN) plant model and the Soilmore » and Water Assessment Tool (SWAT) soil nitrogen dynamics. This model development incorporates FUN's state-of-the-art concept of carbon cost theory and SWAT's strength in representing the impacts of agricultural management on the nitrogen cycle. Parameterizations for direct root and mycorrhizal-associated nitrogen uptake, leaf retranslocation, and symbiotic biological nitrogen fixation are employed from FUN, while parameterizations for nitrogen mineralization, nitrification, immobilization, volatilization, atmospheric deposition, and leaching are based on SWAT. The coupled model is then evaluated at the Kellogg Biological Station – a Long Term Ecological Research site within the US Corn Belt. Results show that the model performs well in capturing the major nitrogen state/flux variables (e.g., soil nitrate and nitrate leaching). Furthermore, the addition of nitrogen dynamics improves the modeling of net primary productivity and evapotranspiration. The model improvement is expected to advance the capability of Noah-MP to simultaneously predict weather and water quality in fully coupled Earth system models.« less

Integration of nitrogen dynamics into the Noah-MP land surface model v1.1 for climate and environmental predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, X.; Yang, Z. -L.; Fisher, J. B.

Climate and terrestrial biosphere models consider nitrogen an important factor in limiting plant carbon uptake, while operational environmental models view nitrogen as the leading pollutant causing eutrophication in water bodies. The community Noah land surface model with multi-parameterization options (Noah-MP) is unique in that it is the next-generation land surface model for the Weather Research and Forecasting meteorological model and for the operational weather/climate models in the National Centers for Environmental Prediction. Here in this study, we add a capability to Noah-MP to simulate nitrogen dynamics by coupling the Fixation and Uptake of Nitrogen (FUN) plant model and the Soilmore » and Water Assessment Tool (SWAT) soil nitrogen dynamics. This model development incorporates FUN's state-of-the-art concept of carbon cost theory and SWAT's strength in representing the impacts of agricultural management on the nitrogen cycle. Parameterizations for direct root and mycorrhizal-associated nitrogen uptake, leaf retranslocation, and symbiotic biological nitrogen fixation are employed from FUN, while parameterizations for nitrogen mineralization, nitrification, immobilization, volatilization, atmospheric deposition, and leaching are based on SWAT. The coupled model is then evaluated at the Kellogg Biological Station – a Long Term Ecological Research site within the US Corn Belt. Results show that the model performs well in capturing the major nitrogen state/flux variables (e.g., soil nitrate and nitrate leaching). Furthermore, the addition of nitrogen dynamics improves the modeling of net primary productivity and evapotranspiration. The model improvement is expected to advance the capability of Noah-MP to simultaneously predict weather and water quality in fully coupled Earth system models.« less

Impact of numerical choices on water conservation in the E3SM Atmosphere Model Version 1 (EAM V1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Kai; Rasch, Philip J.; Taylor, Mark A.

The conservation of total water is an important numerical feature for global Earth system models. Even small conservation problems in the water budget can lead to systematic errors in century-long simulations for sea level rise projection. This study quantifies and reduces various sources of water conservation error in the atmosphere component of the Energy Exascale Earth System Model. Several sources of water conservation error have been identified during the development of the version 1 (V1) model. The largest errors result from the numerical coupling between the resolved dynamics and the parameterized sub-grid physics. A hybrid coupling using different methods formore » fluid dynamics and tracer transport provides a reduction of water conservation error by a factor of 50 at 1° horizontal resolution as well as consistent improvements at other resolutions. The second largest error source is the use of an overly simplified relationship between the surface moisture flux and latent heat flux at the interface between the host model and the turbulence parameterization. This error can be prevented by applying the same (correct) relationship throughout the entire model. Two additional types of conservation error that result from correcting the surface moisture flux and clipping negative water concentrations can be avoided by using mass-conserving fixers. With all four error sources addressed, the water conservation error in the V1 model is negligible and insensitive to the horizontal resolution. The associated changes in the long-term statistics of the main atmospheric features are small. A sensitivity analysis is carried out to show that the magnitudes of the conservation errors decrease strongly with temporal resolution but increase with horizontal resolution. The increased vertical resolution in the new model results in a very thin model layer at the Earth’s surface, which amplifies the conservation error associated with the surface moisture flux correction. We note that for some of the identified error sources, the proposed fixers are remedies rather than solutions to the problems at their roots. Future improvements in time integration would be beneficial for this model.« less

Impact of numerical choices on water conservation in the E3SM Atmosphere Model version 1 (EAMv1)

NASA Astrophysics Data System (ADS)

Zhang, Kai; Rasch, Philip J.; Taylor, Mark A.; Wan, Hui; Leung, Ruby; Ma, Po-Lun; Golaz, Jean-Christophe; Wolfe, Jon; Lin, Wuyin; Singh, Balwinder; Burrows, Susannah; Yoon, Jin-Ho; Wang, Hailong; Qian, Yun; Tang, Qi; Caldwell, Peter; Xie, Shaocheng

2018-06-01

The conservation of total water is an important numerical feature for global Earth system models. Even small conservation problems in the water budget can lead to systematic errors in century-long simulations. This study quantifies and reduces various sources of water conservation error in the atmosphere component of the Energy Exascale Earth System Model. Several sources of water conservation error have been identified during the development of the version 1 (V1) model. The largest errors result from the numerical coupling between the resolved dynamics and the parameterized sub-grid physics. A hybrid coupling using different methods for fluid dynamics and tracer transport provides a reduction of water conservation error by a factor of 50 at 1° horizontal resolution as well as consistent improvements at other resolutions. The second largest error source is the use of an overly simplified relationship between the surface moisture flux and latent heat flux at the interface between the host model and the turbulence parameterization. This error can be prevented by applying the same (correct) relationship throughout the entire model. Two additional types of conservation error that result from correcting the surface moisture flux and clipping negative water concentrations can be avoided by using mass-conserving fixers. With all four error sources addressed, the water conservation error in the V1 model becomes negligible and insensitive to the horizontal resolution. The associated changes in the long-term statistics of the main atmospheric features are small. A sensitivity analysis is carried out to show that the magnitudes of the conservation errors in early V1 versions decrease strongly with temporal resolution but increase with horizontal resolution. The increased vertical resolution in V1 results in a very thin model layer at the Earth's surface, which amplifies the conservation error associated with the surface moisture flux correction. We note that for some of the identified error sources, the proposed fixers are remedies rather than solutions to the problems at their roots. Future improvements in time integration would be beneficial for V1.

Understanding surface-water availability in the Central Valley as a means to projecting future groundwater storage with climate variability

NASA Astrophysics Data System (ADS)

Goodrich, J. P.; Cayan, D. R.

2017-12-01

California's Central Valley (CV) relies heavily on diverted surface water and groundwater pumping to supply irrigated agriculture. However, understanding the spatiotemporal character of water availability in the CV is difficult because of the number of individual farms and local, state, and federal agencies involved in using and managing water. Here we use the Central Valley Hydrologic Model (CVHM), developed by the USGS, to understand the relationships between climatic variability, surface water inputs, and resulting groundwater use over the historical period 1970-2013. We analyzed monthly surface water diversion data from >500 CV locations. Principle components analyses were applied to drivers constructed from meteorological data, surface reservoir storage, ET, land use cover, and upstream inflows, to feed multiple regressions and identify factors most important in predicting surface water diversions. Two thirds of the diversion locations ( 80% of total diverted water) can be predicted to within 15%. Along with monthly inputs, representations of cumulative precipitation over the previous 3 to 36 months can explain an additional 10% of variance, depending on location, compared to results that excluded this information. Diversions in the southern CV are highly sensitive to inter-annual variability in precipitation (R2 = 0.8), whereby more surface water is used during wet years. Until recently, this was not the case in the northern and mid-CV, where diversions were relatively constant annually, suggesting relative insensitivity to drought. In contrast, this has important implications for drought response in southern regions (eg. Tulare Basin) where extended dry conditions can severely limit surface water supplies and lead to excess groundwater pumping, storage loss, and subsidence. In addition to fueling our understanding of spatiotemporal variability in diversions, our ability to predict these water balance components allows us to update CVHM predictions before surface water data are compiled. We can then develop groundwater pumping and storage predictions in real time, and make them available to water managers. In addition, we are working toward future projections by coupling the regional CVHM to downscaled GCM output to assess future scenarios of water availability in this critical region.

Impacts of Irrigation on Land-Atmosphere Coupling Strength Under Different Evapotranspiration Characteristics

NASA Astrophysics Data System (ADS)

Liao, C. Y.; Lo, M. H.

2017-12-01

The Budyko curve displays that the magnitude of evapotranspiration (ET) is limited mainly by the availabilities of energy and water, i.e., under wet conditions, ET is primarily controlled by the available energy, while under dry conditions, ET is primarily controlled by the available water. Land-atmosphere coupling (LAC) strength, which relates to the Budyko curve, is widely discussed because of its contribution towards the improvement in seasonal climate forecasts. For example, the "hot spots" of LAC, where the soil moisture anomalies strongly affect the local precipitation, are found in the transition zones between wet and dry climates. ET of these transition zones is limited by the available water, but at the same time, the surface latent heat flux is large enough to trigger moist convection. Recently, the impacts of irrigation have gained lots of attention, including the change in LAC. Badger and Dirmeyer (2015) analyzed the climate response of Amazon forest replacement by crop with consideration of irrigation in model simulations, discovering negative relationship between added irrigation water and coupling between the soil moisture and the latent heat flux. In addition, Lu et al. (2017) found remarkable decreases of LAC strength with the increase of irrigated cropland percentage in the Great Plains of America. The two studies show that irrigation is possible to affect land-atmosphere coupling strength. However, whether the irrigation process leads to the reduction of coupling strength in other regions of the world remains unclear. This study aims to compare the differences of irrigation impact on land-atmosphere coupling strength between five selected locations undergoing intense irrigation: India, North China Plain, Southwest Europe, Great Plains and Middle East. The spatial divergence of the factor that limits the ET (e.g., either by the available energy or water) will be the focus in this study. Both offline simulation (Community Land Model) and couple simulation (coupled with Community Atmosphere Model) are used to explore the direct change and the subsequent shifts in land-atmosphere interactions. Also, three LAC indices are adopted to quantify the coupling strength between land and atmosphere.

Impacts of the thawing-freezing process on runoff generation in the Sources Area of the Yellow River on the northeastern Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Wu, Xiaoling; Xiang, Xiaohua; Qiu, Chao; Li, Li

2018-06-01

In cold regions, precipitation, air temperature and snow cover significantly influence soil water, heat transfer, the freezing-thawing processes of the active soil layer, and runoff generation. Hydrological regimes of the world's major rivers in cold regions have changed remarkably since the 1960s, but the mechanisms underlying the changes have not yet been fully understood. Using the basic physical processes for water and heat balances and transfers in snow covered soil, a water-heat coupling model for snow cover and its underlying soil layers was established. We found that freezing-thawing processes can affect the thickness of the active layer, storage capacity for liquid water, and subsequent surface runoffs. Based on calculations of thawing-freezing processes, we investigated hydrological processes at Qumalai. The results show that the water-heat coupling model can be used in this region to provide an understanding of the local movement of hydrological regimes.

Arsenic speciation and transport associated with the release of spent geothermal fluids in Mutnovsky field (Kamchatka, Russia)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ilgen, Anastasia G.; Rychagov, Sergey N.; Trainor, Thomas P.

The use of geothermal fluids for the production of electricity poses a risk of contaminating surface waters when spent fluids are discharged into (near) surface environments. Arsenic (As) in particular is a common component in geothermal fluids and leads to a degradation of water quality when present in mobile and bioavailable forms. We have examined changes in arsenic speciation caused by quick transition from high temperature reducing conditions to surface conditions, retention mechanisms, and the extent of transport associated with the release of spent geothermal fluids at the Dachny geothermal fields (Mutnovsky geothermal region), Kamchatka, Russia -- a high temperaturemore » field used for electricity production. In the spent fluids, the arsenic concentration reaches 9 ppm, while in natural hot springs expressed in the vicinity of the field, the As concentration is typically below 10 ppb. The aqueous phase arsenic speciation was determined using Liquid Chromatography (LC) coupled to an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The arsenic speciation in the bottom sediments (< 65 {mu}m fraction) of the local surface waters was analyzed using X-ray Absorption Spectroscopy (XAS). Arsenic in the geothermal source fluids is predominantly found as As(III), while a mixture of As(III)/As(V) is found in the water and sediment of the Falshivaia River downstream from the power plant. The extent of elevated arsenic concentrations in water is limited by adsorption to the bottom sediment and dilution, as determined using Cl{sup -} from the deep well fluids as a tracer. Analysis of the Extended X-ray Absorption Fine Structure (EXAFS) spectra shows that sediment phase arsenic is associated with both Al- and Fe-rich phases with a bi-dentate corner sharing local geometry. The geothermal waste fluids released in the surface water create a localized area of arsenic contamination. The extent of transport of dissolved As is limited to {approx}7 km downstream from the source, while As associated with bottom sediment travels {approx}3 km farther.« less

Modeling Climate-Water Impacts on Electricity Sector Capacity Expansion: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, S. M.; Macknick, J.; Averyt, K.

2014-05-01

Climate change has the potential to exacerbate water availability concerns for thermal power plant cooling, which is responsible for 41% of U.S. water withdrawals. This analysis describes an initial link between climate, water, and electricity systems using the National Renewable Energy Laboratory (NREL) Regional Energy Deployment System (ReEDS) electricity system capacity expansion model. Average surface water projections from Coupled Model Intercomparison Project 3 (CMIP3) data are applied to surface water rights available to new generating capacity in ReEDS, and electric sector growth is compared with and without climate-influenced water rights. The mean climate projection has only a small impact onmore » national or regional capacity growth and water use because most regions have sufficient unappropriated or previously retired water rights to offset climate impacts. Climate impacts are notable in southwestern states that purchase fewer water rights and obtain a greater share from wastewater and other higher-cost water resources. The electric sector climate impacts demonstrated herein establish a methodology to be later exercised with more extreme climate scenarios and a more rigorous representation of legal and physical water availability.« less

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of whole-water recoverable arsenic, boron, and vanadium using inductively coupled plasma-mass spectrometry

USGS Publications Warehouse

Garbarino, John R.

2000-01-01

Analysis of in-bottle digestate by using the inductively coupled plasma?mass spectrometric (ICP?MS) method has been expanded to include arsenic, boron, and vanadium. Whole-water samples are digested by using either the hydrochloric acid in-bottle digestion procedure or the nitric acid in-bottle digestion procedure. When the hydrochloric acid in-bottle digestion procedure is used, chloride must be removed from the digestate by subboiling evaporation before arsenic and vanadium can be accurately determined. Method detection limits for these elements are now 10 to 100 times lower than U.S. Geological Survey (USGS) methods using hydride generation? atomic absorption spectrophotometry (HG? AAS) and inductively coupled plasma? atomic emission spectrometry (ICP?AES), thus providing lower variability at ambient concentrations. The bias and variability of the methods were determined by using results from spike recoveries, standard reference materials, and validation samples. Spike recoveries in reagent-water, surface-water, ground-water, and whole-water recoverable matrices averaged 90 percent for seven replicates; spike recoveries were biased from 25 to 35 percent low for the ground-water matrix because of the abnormally high iron concentration. Results for reference material were within one standard deviation of the most probable value. There was no significant difference between the results from ICP?MS and HG?AAS or ICP?AES methods for the natural whole-water samples that were analyzed.

Studying urban land-atmospheric interactions by coupling an urban canopy model with a single column atmospheric models

NASA Astrophysics Data System (ADS)

Song, J.; Wang, Z.

2013-12-01

Studying urban land-atmospheric interactions by coupling an urban canopy model with a single column atmospheric models Jiyun Song and Zhi-Hua Wang School of Sustainable Engineering and the Built Environment, Arizona State University, PO Box 875306, Tempe, AZ 85287-5306 Landuse landcover changes in urban area will modify surface energy budgets, turbulent fluxes as well as dynamic and thermodynamic structures of the overlying atmospheric boundary layer (ABL). In order to study urban land-atmospheric interactions, we coupled a single column atmospheric model (SCM) to a cutting-edge single layer urban canopy model (SLUCM). Modification of surface parameters such as the fraction of vegetation and engineered pavements, thermal properties of building and pavement materials, and geometrical features of street canyon, etc. in SLUCM dictates the evolution of surface balance of energy, water and momentum. The land surface states then provide lower boundary conditions to the overlying atmosphere, which in turn modulates the modification of ABL structure as well as vertical profiles of temperature, humidity, wind speed and tracer gases. The coupled SLUCM-SCM model is tested against field measurements of surface layer fluxes as well as profiles of temperature and humidity in the mixed layer under convective conditions. After model test, SLUCM-SCM is used to simulate the effect of changing urban land surface conditions on the evolution of ABL structure and dynamics. Simulation results show that despite the prescribed atmospheric forcing, land surface states impose significant impact on the physics of the overlying vertical atmospheric layer. Overall, this numerical framework provides a useful standalone modeling tool to assess the impacts of urban land surface conditions on the local hydrometeorology through land-atmospheric interactions. It also has potentially far-reaching implications to urban ecohydrological services for cities under future expansion and climate challenges.

Exchange of Groundwater and Surface-Water Mediated by Permafrost Response to Seasonal and Long Term Air Temperature Variation

USGS Publications Warehouse

Ge, Shemin; McKenzie, Jeffrey; Voss, Clifford; Wu, Qingbai

2011-01-01

Permafrost dynamics impact hydrologic cycle processes by promoting or impeding groundwater and surface water exchange. Under seasonal and decadal air temperature variations, permafrost temperature changes control the exchanges between groundwater and surface water. A coupled heat transport and groundwater flow model, SUTRA, was modified to simulate groundwater flow and heat transport in the subsurface containing permafrost. The northern central Tibet Plateau was used as an example of model application. Modeling results show that in a yearly cycle, groundwater flow occurs in the active layer from May to October. Maximum groundwater discharge to the surface lags the maximum subsurface temperature by two months. Under an increasing air temperature scenario of 3?C per 100 years, over the initial 40-year period, the active layer thickness can increase by three-fold. Annual groundwater discharge to the surface can experience a similar three-fold increase in the same period. An implication of these modeling results is that with increased warming there will be more groundwater flow in the active layer and therefore increased groundwater discharge to rivers. However, this finding only holds if sufficient upgradient water is available to replenish the increased discharge. Otherwise, there will be an overall lowering of the water table in the recharge portion of the catchment.

Fast trace determination of nine odorant and estrogenic chloro- and bromo-phenolic compounds in real water samples through automated solid-phase extraction coupled with liquid chromatography tandem mass spectrometry.

PubMed

Yuan, Su-Fen; Liu, Ze-Hua; Lian, Hai-Xian; Yang, Chuang-Tao; Lin, Qing; Yin, Hua; Lin, Zhang; Dang, Zhi

2018-02-01

A fast and reliable method was developed for simultaneous trace determination of nine odorous and estrogenic chloro- and bromo-phenolic compounds (CPs and BPs) in water samples using solid-phase extraction (SPE) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). For sample preparation, the extraction efficiencies of two widely applied cartridges Oasis HLB and Sep-Pak C18 were compared, and the Oasis HLB cartridge showed much better extraction performance; pH of water sample also plays important role on extraction, and pH = 2-3 was found to be most appropriate. For separation of the target compounds, small addition of ammonium hydroxide can obviously improve the detection sensitivity, and the optimized addition concentration was determined as 0.2%. The developed efficient method was validated and showed excellent linearity (R 2  > 0.995), low limit of detection (LOD, 1.9-6.2 ng/L), and good recovery efficiencies of 57-95% in surface and tap water with low relative standard deviation (RSD, 1.3-17.4%). The developed method was finally applied to one tap and one surface water samples and most of these nine targets were detected, but all of them were below their odor thresholds, and their estrogen equivalent (EEQ) were also very low.

Water flux through a semi-deciduous forest grove of the Orinoco savannas.

PubMed

San José, José J; Montes, Ruben A; Florentino, Adriana

1995-02-01

Water relations were analysed in a semi-deciduous forest grove occurring in the oxisols of the Orinoco savannas. This grove has a shallow unconsolidated ironstone cuirass, which is overlaid by a sandy loam layer (0.0-0.5 m) that contains more than 90% of the grove forest root phytomass. Evapotranspiration and through drainage were calculated by using data from the soil profile as related to physical characteristics of the site root zone, hydraulic conductivity, volumetric water content and potential hydraulic gradient. Mean annual evapotranspiration was 783 mm year -1 and annual through drainage below the root zone was 14% (162 mm year -1 ) of the gross rainfall. This drainage recharged the 42% of the annual saturation deficit of the water table. Similar mean annual evapotranspiration (770 mm year -1 ) was also calculated by using the water balance components. The mean daily coupling omega factor (Ω) between the grove canopy and the surrounding atmosphere indicated that a high degree of coupling (Ω=0.14±0.16) occurs in the grove and evapotranspiration was mainly controlled by surface conductance. As the dry season proceeded, the soil saturation deficit (δθ) increased rapidly resulting in a threshold surface conductance (0.030-0.005 m s -1 ) for δθ ranging from 0.05 to 0.10. Hypotheses to explain the omnipresence of perennial species in the wide range of physical conditions in neotropical savannas are discussed.

Coupling between the Dynamics of Water and Surfactants in Lyotropic Liquid Crystals.

PubMed

McDaniel, Jesse G; Yethiraj, Arun

2017-05-18

Bilayers composed of lipid or surfactant molecules are central to biological membranes and lamellar lyotropic liquid crystalline (LLC) phases. Common to these systems are phases that exhibit either ordered or disordered packing of the hydrophobic tails. In this work, we study the impact of surfactant ordering, i.e., disordered L α and ordered L β LLC phases, on the dynamics of water and sodium ions in the lamellar phases of dicarboxylate gemini surfactants. We study the different phases at identical hydration levels by changing the length of the hydrophobic tails; surfactants with shorter tails form L α phases and those with longer tails form L β phases. We find that the L α phases exhibit lower density and greater compressibility than the L β phases, with a hydration-dependent headgroup surface area. These structural differences significantly affect the relative dynamic properties of the phases, primarily the mobility of the surfactant molecules tangential to the bilayer surface, as well as the rates of water and ion diffusion. We find ∼20-50% faster water diffusion in the L α phases compared to the L β phases, with the differences most pronounced at low hydration. This coupling between water dynamics and surfactant mobility is verified using additional simulations in which the surfactant tails are frozen. Our study indicates that gemini surfactant LLCs provide an important prototypical system for characterizing properties shared with more complex biological lipid membranes.

Projections of Declining Surface-Water Availability for the Southwestern United States

NASA Technical Reports Server (NTRS)

Seager, Richard; Ting, Mingfang; Li, Cuihua; Naik, Naomi; Cook, Benjamin; Nakamura, Jennifer; Liu, Haibo

2012-01-01

Global warming driven by rising greenhouse-gas concentrations is expected to cause wet regions of the tropics and mid to high latitudes to get wetter and subtropical dry regions to get drier and expand polewards. Over southwest North America, models project a steady drop in precipitation minus evapotranspiration, P -- E, the net flux of water at the land surface, leading to, for example, a decline in Colorado River flow. This would cause widespread and important social and ecological consequences. Here, using new simulations from the Coupled Model Intercomparison Project Five, to be assessed in Intergovernmental Panel on Climate Change Assessment Report Five, we extend previous work by examining changes in P, E, runoff and soil moisture by season and for three different water resource regions. Focusing on the near future, 2021-2040, the new simulations project declines in surface-water availability across the southwest that translate into reduced soil moisture and runoff in California and Nevada, the Colorado River headwaters and Texas.

Electron affinity of liquid water

DOE PAGES

Gaiduk, Alex P.; Pham, Tuan Anh; Govoni, Marco; ...

2018-01-16

Understanding redox and photochemical reactions in aqueous environments requires a precise knowledge of the ionization potential and electron affinity of liquid water. The former has been measured, but not the latter. We predict the electron affinity of liquid water and of its surface from first principles, coupling path-integral molecular dynamics with ab initio potentials, and many-body perturbation theory. Our results for the surface (0.8 eV) agree well with recent pump-probe spectroscopy measurements on amorphous ice. Those for the bulk (0.1-0.3 eV) differ from several estimates adopted in the literature, which we critically revisit. We show that the ionization potential ofmore » the bulk and surface are almost identical; instead their electron affinities differ substantially, with the conduction band edge of the surface much deeper in energy than that of the bulk. We also discuss the significant impact of nuclear quantum effects on the fundamental gap and band edges of the liquid.« less

Electron affinity of liquid water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaiduk, Alex P.; Pham, Tuan Anh; Govoni, Marco

Understanding redox and photochemical reactions in aqueous environments requires a precise knowledge of the ionization potential and electron affinity of liquid water. The former has been measured, but not the latter. We predict the electron affinity of liquid water and of its surface from first principles, coupling path-integral molecular dynamics with ab initio potentials, and many-body perturbation theory. Our results for the surface (0.8 eV) agree well with recent pump-probe spectroscopy measurements on amorphous ice. Those for the bulk (0.1-0.3 eV) differ from several estimates adopted in the literature, which we critically revisit. We show that the ionization potential ofmore » the bulk and surface are almost identical; instead their electron affinities differ substantially, with the conduction band edge of the surface much deeper in energy than that of the bulk. We also discuss the significant impact of nuclear quantum effects on the fundamental gap and band edges of the liquid.« less

Relationship between changes in the upper and lower tropospheric water vapor: A revisit

NASA Astrophysics Data System (ADS)

Yang, M.; Sun, D. Z.; Zhang, G. J.

2017-12-01

Upper tropospheric water vapor response to enhanced greenhouse gas forcing is as important as the lower tropospheric water vapor response in determining climate sensitivity. Early studies using older versions of climate models have suggested that the upper- and lower-troposphere water vapor changes are more strongly coupled in the climate models than in the observations. Here we reexamine this issue using a state-of-the-art climate model—the NCAR community model CAM5. Specifically, we have calculated the correlations between interannual variations of specific humidity in all levels of the troposphere with that at the surface in CAM5 and in the observations (as represented by the updated ERA-Interim and NCEP reanalysis). It is found that the previously noted biases in how strongly upper tropospheric water vapor and lower troposphere water vapor are linked still exist in CAM5—the change in the tropical averaged upper tropospheric water vapor is more strongly correlated with the change in the surface. However, this bias disappears in the averaged correlation obtained by averaging the point-by-point correlations over the tropics. The spatial pattern of the point-by-point correlations reveals that the better agreement between the model and the observations is related to the opposite model biases in different regions: the correlation is weaker in the model in the western Pacific, but stronger in the central and eastern Pacific. Further analysis of precipitation fields suggests that the weaker (stronger) coupling between tropospheric water vapor and surface moisture over western (central-eastern) Pacific in model is related to weaker (stronger) simulated convective activities in these regions. More specifically, during El Nino, the model has excessive deep convection in the central Pacific, but too littler deep convection in western Pacific. Implications of the results are discussed in the context of climate change as well as in the context of how to improve the model in this regard.

Caught in the act: the first record of copulating fossil vertebrates.

PubMed

Joyce, Walter G; Micklich, Norbert; Schaal, Stephan F K; Scheyer, Torsten M

2012-10-23

The behaviour of fossil organisms can typically be inferred only indirectly, but rare fossil finds can provide surprising insights. Here, we report from the Eocene Messel Pit Fossil Site between Darmstadt and Frankfurt, Germany numerous pairs of the fossil carettochelyid turtle Allaeochelys crassesculpta that represent for the first time among fossil vertebrates couples that perished during copulation. Females of this taxon can be distinguished from males by their relatively shorter tails and development of plastral kinesis. The preservation of mating pairs has important taphonomic implications for the Messel Pit Fossil Site, as it is unlikely that the turtles would mate in poisonous surface waters. Instead, the turtles initiated copulation in habitable surface waters, but perished when their skin absorbed poisons while sinking into toxic layers. The mating pairs from Messel are therefore more consistent with a stratified, volcanic maar lake with inhabitable surface waters and a deadly abyss.

Quantifying Groundwater Fluctuations in the Southern High Plains with GIS and Geostatistics

NASA Astrophysics Data System (ADS)

Whitehead, B.

2008-12-01

Groundwater as a dwindling non-renewable natural resource has been an important research theme in agricultural studies coupled with human-environment interaction. This research incorporated contemporary Geographic Information System (GIS) methodologies and a universal kriging interpolator (geostatistics) to develop depth to groundwater surfaces for the southern portion of the High Plains, or Ogallala, aquifer. The variations in the interpolated surfaces were used to calculate the volume of water mined from the aquifer from 1980 to 2005. The findings suggest a nearly inverse relationship to the water withdrawal scenarios derived by the United States Geological Survey (USGS) during the Regional Aquifer System Analysis (RASA) performed in the early 1980's. These results advocate further research into regional climate change, groundwater-surface water interaction, and recharge mechanisms in the region, and provide a substantial contribution to the continuing and contentious issue concerning the environmental sustainability of the High Plains.

GEOCHEMISTRY OF SUBSURFACE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

EPA Science Inventory

Reactive barriers that couple subsurface fluid flow with a passive chemical treatment zone are emerging, cost effective approaches for in-situ remediation of contaminated groundwater. Factors such as the build-up of surface precipitates, bio-fouling, and changes in subsurface tr...

How coalescing droplets jump.

PubMed

Enright, Ryan; Miljkovic, Nenad; Sprittles, James; Nolan, Kevin; Mitchell, Robert; Wang, Evelyn N

2014-10-28

Surface engineering at the nanoscale is a rapidly developing field that promises to impact a range of applications including energy production, water desalination, self-cleaning and anti-icing surfaces, thermal management of electronics, microfluidic platforms, and environmental pollution control. As the area advances, more detailed insights of dynamic wetting interactions on these surfaces are needed. In particular, the coalescence of two or more droplets on ultra-low adhesion surfaces leads to droplet jumping. Here we show, through detailed measurements of jumping droplets during water condensation coupled with numerical simulations of binary droplet coalescence, that this process is fundamentally inefficient with only a small fraction of the available excess surface energy (≲ 6%) convertible into translational kinetic energy. These findings clarify the role of internal fluid dynamics during the jumping droplet coalescence process and underpin the development of systems that can harness jumping droplets for a wide range of applications.

Numerical analysis of the bucket surface roughness effects in Pelton turbine

NASA Astrophysics Data System (ADS)

Xiao, Y. X.; Zeng, C. J.; Zhang, J.; Yan, Z. G.; Wang, Z. W.

2013-12-01

The internal flow of a Pelton turbine is quite complex. It is difficult to analyse the unsteady free water sheet flow in the rotating bucket owing to the lack of a sound theory. Affected by manufacturing technique and silt abrasion during the operation, the bucket surface roughness of Pelton turbine may be too great, and thereby influence unit performance. To investigate the effect of bucket roughness on Pelton turbine performance, this paper presents the numerical simulation of the interaction between the jet and the bucket in a Pelton turbine. The unsteady three-dimensional numerical simulations were performed with CFX code by using the SST turbulence model coupling the two-phase flow volume of fluid method. Different magnitude orders of bucket surface roughness were analysed and compared. Unsteady numerical results of the free water sheet flow patterns on bucket surface, torque and unit performance for each bucket surface roughness were generated. The total pressure distribution on bucket surface is used to show the free water sheet flow pattern on bucket surface. By comparing the variation of water sheet flow patterns on bucket surface with different roughness, this paper qualitatively analyses how the bucket surface roughness magnitude influences the impeding effect on free water sheet flow. Comparison of the torque variation of different bucket surface roughness highlighted the effect of the bucket surface roughness on the Pelton turbine output capacity. To further investigate the effect of bucket surface roughness on Pelton turbine performance, the relation between the relative efficiency loss rate and bucket surface roughness magnitude is quantitatively analysed. The result can be used to predict and evaluate the Pelton turbine performance.

Reliable retrieval of atmospheric and aquatic parameters in coastal and inland environments from polar-orbiting and geostationary platforms: challenges and opportunities

NASA Astrophysics Data System (ADS)

Stamnes, Knut; Li, Wei; Lin, Zhenyi; Fan, Yongzhen; Chen, Nan; Gatebe, Charles; Ahn, Jae-Hyun; Kim, Wonkook; Stamnes, Jakob J.

2017-04-01

Simultaneous retrieval of aerosol and surface properties by means of inverse techniques based on a coupled atmosphere-surface radiative transfer model, neural networks, and optimal estimation can yield considerable improvements in retrieval accuracy in complex aquatic environments compared with traditional methods. Remote sensing of such environments represent specific challenges due (i) the complexity of the atmosphere and water inherent optical properties, (ii) unique bidirectional dependencies of the water-leaving radiance, and (iii) the desire to do retrievals for large solar zenith and viewing angles. We will discuss (a) how challenges related to atmospheric gaseous absorption, absorbing aerosols, and turbid waters can be addressed by using a coupled atmosphere-surface radiative transfer (forward) model in the retrieval process, (b) how the need to correct for bidirectional effects can be accommodated in a systematic and reliable manner, (c) how polarization information can be utilized, (d) how the curvature of the atmosphere can be taken into account, and (e) how neural networks and optimal estimation can be used to obtain fast yet accurate retrievals. Special emphasis will be placed on how information from existing and future sensors deployed on polar-orbiting and geostationary platforms can be obtained in a reliable and accurate manner. The need to provide uncertainty assessments and error budgets will also be discussed.

Development of a magnetic solid-phase extraction coupled with high-performance liquid chromatography method for the analysis of polyaromatic hydrocarbons.

PubMed

Ma, Yan; Xie, Jiawen; Jin, Jing; Wang, Wei; Yao, Zhijian; Zhou, Qing; Li, Aimin; Liang, Ying

2015-07-01

A novel magnetic solid phase extraction coupled with high-performance liquid chromatography method was established to analyze polyaromatic hydrocarbons in environmental water samples. The extraction conditions, including the amount of extraction agent, extraction time, pH and the surface structure of the magnetic extraction agent, were optimized. The results showed that the amount of extraction agent and extraction time significantly influenced the extraction performance. The increase in the specific surface area, the enlargement of pore size, and the reduction of particle size could enhance the extraction performance of the magnetic microsphere. The optimized magnetic extraction agent possessed a high surface area of 1311 m(2) /g, a large pore size of 6-9 nm, and a small particle size of 6-9 μm. The limit of detection for phenanthrene and benzo[g,h,i]perylene in the developed analysis method was 3.2 and 10.5 ng/L, respectively. When applied to river water samples, the spiked recovery of phenanthrene and benzo[g,h,i]perylene ranged from 89.5-98.6% and 82.9-89.1%, respectively. Phenanthrene was detected over a concentration range of 89-117 ng/L in three water samples withdrawn from the midstream of the Huai River, and benzo[g,h,i]perylene was below the detection limit. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Assess Climate Change's Impact on Coastal Rivers using a Coupled Climate-Hydrology Model

NASA Astrophysics Data System (ADS)

Xue, Z. G.; Gochis, D.; Yu, W.; Zang, Z.; Sampson, K. M.; Keim, B. D.

2016-12-01

In this study we present a coupled climate-hydrological model reproducing the water cycle of three coastal river basins along the northern Gulf of Mexico for the past three decades (1985-2014). Model simulated climate condition, surface physics, and streamflow were well validated against in situ data and satellite-derived products, giving us the confidence that the newly developed WRF-Hydro model can be a robust tool for evaluating climate change's impact on hydrological regime. Trend analysis of model simulated monthly and annual time series indicates that local climate is getting hotter and dryer, specifically during the growing season. Wavelet analysis reveals that local evapotranspiration is strongly correlated with temperature, while soil moisture, water surplus, and streamflow are coupled with precipitation. In addition, local climate is closely correlated with large-scale climate dynamics such as AMO and ENSO. A possible change-point is detected around year 2004, after which, the monthly precipitation decreased by 14.2%, evapotranspiration increased by 2.9%, and water surplus decreased by 36.5%. The implication of the difference between the water surplus (runoff) calculated using the classic Thornthwaite method and river discharge estimated using streamflow records to the coastal environment is also discussed.

Sulfur mass-independent fractionation in subsurface fracture waters indicates a long-standing sulfur cycle in Precambrian rocks.

PubMed

Li, L; Wing, B A; Bui, T H; McDermott, J M; Slater, G F; Wei, S; Lacrampe-Couloume, G; Lollar, B Sherwood

2016-10-27

The discovery of hydrogen-rich waters preserved below the Earth's surface in Precambrian rocks worldwide expands our understanding of the habitability of the terrestrial subsurface. Many deep microbial ecosystems in these waters survive by coupling hydrogen oxidation to sulfate reduction. Hydrogen originates from water-rock reactions including serpentinization and radiolytic decomposition of water induced by decay of radioactive elements in the host rocks. The origin of dissolved sulfate, however, remains unknown. Here we report, from anoxic saline fracture waters ∼2.4 km below surface in the Canadian Shield, a sulfur mass-independent fractionation signal in dissolved sulfate. We demonstrate that this sulfate most likely originates from oxidation of sulfide minerals in the Archaean host rocks through the action of dissolved oxidants (for example, HO · and H 2 O 2 ) themselves derived from radiolysis of water, thereby providing a coherent long-term mechanism capable of supplying both an essential electron donor (H 2 ) and a complementary acceptor (sulfate) for the deep biosphere.

Regional Responses to Black Carbon Aerosols: The Importance of Air-Sea Interaction

NASA Astrophysics Data System (ADS)

Gnanadesikan, A.; Scott, A. A.; Pradal, M.-A.; Seviour, W. J. M.; Waugh, D. W.

2017-12-01

The impact of modern black carbon aerosols on climate via their changes in radiative balance is studied using a coupled model where sea surface temperatures (SSTs) are allowed to vary and an atmosphere-only version of the same model where SSTs are held fixed. Allowing the ocean to respond is shown to have a profound impact on the pattern of temperature change. Particularly, large impacts are found in the North Pacific (which cools by up to 1 K in the coupled model) and in north central Asia (which warms in the coupled simulation and cools in the fixed SST simulation). Neither set of experiments shows large changes in surface temperatures in the Southeast Asian region where the atmospheric burden of black carbon is highest. These results are related to the stabilization of the atmosphere and changes in oceanic heat transport. Over the North Pacific, atmospheric stabilization results in an increase in stratiform clouds. The resulting shading reduces evaporation, freshening the surface layer of the ocean and reducing the inflow of warm subtropical waters. Over the land, a delicate balance between greater atmospheric absorption, shading of the surface and changes in latent cooling of the surface helps to determine whether warming or cooling is seen. Our results emphasize the importance of coupling in determining the response of the climate system to black carbon and suggest that black carbon may play an important role in modulating climate change over the North Pacific.

Groundwater impacts on surface water quality and nutrient loads in lowland polder catchments: monitoring the greater Amsterdam area

NASA Astrophysics Data System (ADS)

Yu, Liang; Rozemeijer, Joachim; van Breukelen, Boris M.; Ouboter, Maarten; van der Vlugt, Corné; Broers, Hans Peter

2018-01-01

The Amsterdam area, a highly manipulated delta area formed by polders and reclaimed lakes, struggles with high nutrient levels in its surface water system. The polders receive spatially and temporally variable amounts of water and nutrients via surface runoff, groundwater seepage, sewer leakage, and via water inlets from upstream polders. Diffuse anthropogenic sources, such as manure and fertiliser use and atmospheric deposition, add to the water quality problems in the polders. The major nutrient sources and pathways have not yet been clarified due to the complex hydrological system in lowland catchments with both urban and agricultural areas. In this study, the spatial variability of the groundwater seepage impact was identified by exploiting the dense groundwater and surface water monitoring networks in Amsterdam and its surrounding polders. A total of 25 variables (concentrations of total nitrogen (TN), total phosphorus (TP), NH4, NO3, HCO3, SO4, Ca, and Cl in surface water and groundwater, N and P agricultural inputs, seepage rate, elevation, land-use, and soil type) for 144 polders were analysed statistically and interpreted in relation to sources, transport mechanisms, and pathways. The results imply that groundwater is a large source of nutrients in the greater Amsterdam mixed urban-agricultural catchments. The groundwater nutrient concentrations exceeded the surface water environmental quality standards (EQSs) in 93 % of the polders for TP and in 91 % for TN. Groundwater outflow into the polders thus adds to nutrient levels in the surface water. High correlations (R2 up to 0.88) between solutes in groundwater and surface water, together with the close similarities in their spatial patterns, confirmed the large impact of groundwater on surface water chemistry, especially in the polders that have high seepage rates. Our analysis indicates that the elevated nutrient and bicarbonate concentrations in the groundwater seepage originate from the decomposition of organic matter in subsurface sediments coupled to sulfate reduction and possibly methanogenesis. The large loads of nutrient-rich groundwater seepage into the deepest polders indirectly affect surface water quality in the surrounding area, because excess water from the deep polders is pumped out and used to supply water to the surrounding infiltrating polders in dry periods. The study shows the importance of the connection between groundwater and surface water nutrient chemistry in the greater Amsterdam area. We expect that taking account of groundwater-surface water interaction is also important in other subsiding and urbanising deltas around the world, where water is managed intensively in order to enable agricultural productivity and achieve water-sustainable cities.

Interfacing a one-dimensional lake model with a single-column atmospheric model: 2. Thermal response of the deep Lake Geneva, Switzerland under a 2 × CO2 global climate change

NASA Astrophysics Data System (ADS)

Perroud, Marjorie; Goyette, StéPhane

2012-06-01

In the companion to the present paper, the one-dimensional k-ɛ lake model SIMSTRAT is coupled to a single-column atmospheric model, nicknamed FIZC, and an application of the coupled model to the deep Lake Geneva, Switzerland, is described. In this paper, the response of Lake Geneva to global warming caused by an increase in atmospheric carbon dioxide concentration (i.e., 2 × CO2) is investigated. Coupling the models allowed for feedbacks between the lake surface and the atmosphere and produced changes in atmospheric moisture and cloud cover that further modified the downward radiation fluxes. The time evolution of atmospheric variables as well as those of the lake's thermal profile could be reproduced realistically by devising a set of adjustable parameters. In a "control" 1 × CO2 climate experiment, the coupled FIZC-SIMSTRAT model demonstrated genuine skills in reproducing epilimnetic and hypolimnetic temperatures, with annual mean errors and standard deviations of 0.25°C ± 0.25°C and 0.3°C ± 0.15°C, respectively. Doubling the CO2 concentration induced an atmospheric warming that impacted the lake's thermal structure, increasing the stability of the water column and extending the stratified period by 3 weeks. Epilimnetic temperatures were seen to increase by 2.6°C to 4.2°C, while hypolimnion temperatures increased by 2.2°C. Climate change modified components of the surface energy budget through changes mainly in air temperature, moisture, and cloud cover. During summer, reduced cloud cover resulted in an increase in the annual net solar radiation budget. A larger water vapor deficit at the air-water interface induced a cooling effect in the lake.

Importance of Vertical Coupling in Agricultural Models on Assimilation of Satellite-derived Soil Moisture

NASA Astrophysics Data System (ADS)

Mladenova, I. E.; Crow, W. T.; Teng, W. L.; Doraiswamy, P.

2010-12-01

Crop yield in crop production models is simulated as a function of weather, ground conditions and management practices and it is driven by the amount of nutrients, heat and water availability in the root-zone. It has been demonstrated that assimilation of satellite-derived soil moisture data has the potential to improve the model root-zone soil water (RZSW) information. However, the satellite estimates represent the moisture conditions of the top 3 cm to 5 cm of the soil profile depending on system configuration and surface conditions (i.e. soil wetness, density of the canopy cover, etc). The propagation of this superficial information throughout the profile will depend on the model physics. In an Ensemble Kalman Filter (EnKF) data assimilation system, as the one examined here, the update of each soil layer is done through the Kalman Gain, K. K is a weighing factor that determines how much correction will be performed on the forecasts. Furthermore, K depends on the strength of the correlation between the surface and the root-zone soil moisture; the stronger this correlation is, the more observations will impact the analysis. This means that even if the satellite-derived product has higher sensitivity and accuracy as compared to the model estimates, the improvement of the RZSW will be negligible if the surface-root zone coupling is weak, where the later is determined by the model subsurface physics. This research examines: (1) the strength of the vertical coupling in the Environmental Policy Integrated Climate (EPIC) model over corn and soybeans covered fields in Iowa, US, (2) the potential to improve EPIC RZSW information through assimilation of satellite soil moisture data derived from the Advanced Microwave Scanning Radiometer (AMSR-E) and (3) the impact of the vertical coupling on the EnKF performance.

Coupled basin-scale water resource models for arid and semiarid regions

NASA Astrophysics Data System (ADS)

Winter, C.; Springer, E.; Costigan, K.; Fasel, P.; Mniewski, S.; Zyvoloski, G.

2003-04-01

Managers of semi-arid and arid water resources must allocate increasingly variable surface sources and limited groundwater resources to growing demands. This challenge is leading to a new generation of detailed computational models that link multiple interacting sources and demands. We will discuss a new computational model of arid region hydrology that we are parameterizing for the upper Rio Grande Basin of the United States. The model consists of linked components for the atmosphere (the Regional Atmospheric Modeling System, RAMS), surface hydrology (the Los Alamos Distributed Hydrologic System, LADHS), and groundwater (the Finite Element Heat and Mass code, FEHM), and the couplings between them. The model runs under the Parallel Application WorkSpace software developed at Los Alamos for applications running on large distributed memory computers. RAMS simulates regional meteorology coupled to global climate data on the one hand and land surface hydrology on the other. LADHS generates runoff by infiltration or saturation excess mechanisms, as well as interception, evapotranspiration, and snow accumulation and melt. FEHM simulates variably saturated flow and heat transport in three dimensions. A key issue is to increase the components’ spatial and temporal resolution to account for changes in topography and other rapidly changing variables that affect results such as soil moisture distribution or groundwater recharge. Thus, RAMS’ smallest grid is 5 km on a side, LADHS uses 100 m spacing, while FEHM concentrates processing on key volumes by means of an unstructured grid. Couplings within our model are based on new scaling methods that link groundwater-groundwater systems and streams to aquifers and we are developing evapotranspiration methods based on detailed calculations of latent heat and vegetative cover. Simulations of precipitation and soil moisture for the 1992-93 El Nino year will be used to demonstrate the approach and suggest further needs.

Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles. Part 1. Aggregation and dissolution.

PubMed

Unrine, Jason M; Colman, Benjamin P; Bone, Audrey J; Gondikas, Andreas P; Matson, Cole W

2012-07-03

To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet-visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22-28% of the particulate Ag was associated with thiols and 5-14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.

A new capture fraction method to map how pumpage affects surface water flow.

PubMed

Leake, Stanley A; Reeves, Howard W; Dickinson, Jesse E

2010-01-01

All groundwater pumped is balanced by removal of water somewhere, initially from storage in the aquifer and later from capture in the form of increase in recharge and decrease in discharge. Capture that results in a loss of water in streams, rivers, and wetlands now is a concern in many parts of the United States. Hydrologists commonly use analytical and numerical approaches to study temporal variations in sources of water to wells for select points of interest. Much can be learned about coupled surface/groundwater systems, however, by looking at the spatial distribution of theoretical capture for select times of interest. Development of maps of capture requires (1) a reasonably well-constructed transient or steady state model of an aquifer with head-dependent flow boundaries representing surface water features or evapotranspiration and (2) an automated procedure to run the model repeatedly and extract results, each time with a well in a different location. This paper presents new methods for simulating and mapping capture using three-dimensional groundwater flow models and presents examples from Arizona, Oregon, and Michigan.

Direct nutritional link between 600-m deep cold-water corals and surface productivity

NASA Astrophysics Data System (ADS)

Soetaert, Karline; Mohn, Christian; Rengstorff, Anna; Grehan, Anthony; van Oevelen, Dick

2016-04-01

Cold-water corals (CWC) form deep-sea reefs that are found in all of the world's oceans, with an areal extent at par with that of tropical coral reefs, and are recognised hotspots of biodiversity and metabolic activity. Yet, it remains largely enigmatic how these rich CWC reefs can thrive in a cold and dark environment that is considered to be strongly food-limited. Here, we use a novel benthic-pelagic modeling approach, which involves coupling models of hydrodynamics, biogeochemistry and habitat suitability, to unravel organic matter delivery to reef mounds at a water depth of 600 m that are capped with a thriving CWC reef community at Rockall Bank (NE Atlantic). Model simulations show that the interaction between 300-m high reef mounds and spring tidal currents induces episodic downwelling events that establish a vertical coupling between 600-m deep CWC with surface productivity. We therefore conclude that there is a positive feedback between CWC mound growth and organic matter supply. This episodic downwelling strongly enhances carbon sequestration to the deep ocean and the ubiquitous occurrence of topographic rises along the ocean margins suggests that a topographically-induced benthic-pelagic carbon pump could be of global importance.

Karst medium characterization and simulation of groundwater flow in Lijiang Riversed, China

NASA Astrophysics Data System (ADS)

Hu, B. X.

2015-12-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

Simulation of groundwater flow and evaluation of carbon sink in Lijiang Rivershed, China

NASA Astrophysics Data System (ADS)

Hu, Bill X.; Cao, Jianhua; Tong, Juxiu; Gao, Bing

2016-04-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

Implementation of Solute Transport in the Vadose Zone into the `HYDRUS Package for MODFLOW'

NASA Astrophysics Data System (ADS)

Simunek, J.; Beegum, S.; Szymkiewicz, A.; Sudheer, K. P.

2017-12-01

The 'HYDRUS package for MODFLOW' was developed by Seo et al. (2007) and Twarakavi et al. (2008) to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package, which is based on the HYDRUS-1D model (Šimůnek et al., 2016) simulating unsaturated water flow in the vadose zone, was incorporated into MODFLOW (Harbaugh et al., 2000) simulating saturated groundwater flow. The HYDRUS package in the coupled model can be used to represent the effects of various unsaturated zone processes, including infiltration, evaporation, root water uptake, capillary rise, and recharge in homogeneous or layered soil profiles. The coupled model is effective in addressing spatially-variable saturated-unsaturated hydrological processes at the regional scale, allowing for complex layering in the unsaturated zone, spatially and temporarily variable water fluxes at the soil surface and in the root zone, and with alternating recharge and discharge fluxes (Twarakavi et al., 2008). One of the major limitations of the coupled model was that it could not be used to simulate at the same time solute transport. However, solute transport is highly dependent on water table fluctuations due to temporal and spatial variations in groundwater recharge. This is an important concern when the coupled model is used for analyzing groundwater contamination due to transport through the unsaturated zone. The objective of this study is to integrate the solute transport model (the solute transport part of HYDRUS-1D for the unsaturated zone and MT3DMS (Zheng and Wang, 1999; Zheng, 2009) for the saturated zone) into an existing coupled water flow model. The unsaturated zone component of the coupled model can consider solute transport involving many biogeochemical processes and reactions, including first-order degradation, volatilization, linear or nonlinear sorption, one-site kinetic sorption, two-site sorption, and two-kinetic sites sorption (Šimůnek and van Genuchten, 2008). Due to complex interactions at the groundwater table, certain modifications of the pressure head (compared to the original coupling) and solute concentration profiles were incorporated into the HYDRUS package. The developed integrated model is verified using HYDRUS-2D and analyzed for its computational time requirements.

Theoretical studies on the coupling interactions in H2SO4···HOO˙···(H2O)n (n = 0-2) clusters: toward understanding the role of water molecules in the uptake of HOO˙ radical by sulfuric acid aerosols.

PubMed

Li, Ping; Ma, Zhiying; Wang, Weihua; Zhai, Yazhou; Sun, Haitao; Bi, Siwei; Bu, Yuxiang

2011-01-21

A detailed knowledge of coupling interactions among sulfuric acid (H(2)SO(4)), the hydroperoxyl radical (HOO˙), and water molecules (H(2)O) is crucial for the better understanding of the uptake of HOO˙ radicals by sulfuric acid aerosols at different atmospheric humidities. In the present study, the equilibrium structures, binding energies, equilibrium distributions, and the nature of the coupling interactions in H(2)SO(4)···HOO˙···(H(2)O)(n) (n = 0-2) clusters have been systematically investigated at the B3LYP/6-311++G(3df,3pd) level of theory in combination with the atoms in molecules (AIM) theory, natural bond orbital (NBO) method, energy decomposition analyses, and ab initio molecular dynamics. Two binary, five ternary, and twelve tetramer clusters possessing multiple intermolecular H-bonds have been located on their potential energy surfaces. Two different modes for water molecules have been observed to influence the coupling interactions between H(2)SO(4) and HOO˙ through the formations of intermolecular H-bonds with or without breaking the original intermolecular H-bonds in the binary H(2)SO(4)···HOO˙ cluster. It was found that the introduction of one or two water molecules can efficiently enhance the interactions between H(2)SO(4) and HOO˙, implying the positive role of water molecules in the uptake of the HOO˙ radical by sulfuric acid aerosols. Additionally, the coupling interaction modes of the most stable clusters under study have been verified by the ab initio molecular dynamics.

Assessment of impacts of climate change on surface water availability using coupled SWAT and WEAP models: case of upper Pangani River Basin, Tanzania

NASA Astrophysics Data System (ADS)

Kishiwa, Peter; Nobert, Joel; Kongo, Victor; Ndomba, Preksedis

2018-05-01

This study was designed to investigate the dynamics of current and future surface water availability for different water users in the upper Pangani River Basin under changing climate. A multi-tier modeling technique was used in the study, by coupling the Soil and Water Assessment Tool (SWAT) and Water Evaluation And Planning (WEAP) models, to simulate streamflows under climate change and assess scenarios of future water availability to different socio-economic activities by year 2060. Six common Global Circulation Models (GCMs) from WCRP-CMIP3 with emissions Scenario A2 were selected. These are HadCM3, HadGEM1, ECHAM5, MIROC3.2MED, GFDLCM2.1 and CSIROMK3. They were downscaled by using LARS-WG to station scale. The SWAT model was calibrated with observed data and utilized the LARS-WG outputs to generate future streamflows before being used as input to WEAP model to assess future water availability to different socio-economic activities. GCMs results show future rainfall increase in upper Pangani River Basin between 16-18 % in 2050s relative to 1980-1999 periods. Temperature is projected to increase by an average of 2 °C in 2050s, relative to baseline period. Long-term mean streamflows is expected to increase by approximately 10 %. However, future peak flows are estimated to be lower than the prevailing average peak flows. Nevertheless, the overall annual water demand in Pangani basin will increase from 1879.73 Mm3 at present (2011) to 3249.69 Mm3 in the future (2060s), resulting to unmet demand of 1673.8 Mm3 (51.5 %). The impact of future shortage will be more severe in irrigation where 71.12 % of its future demand will be unmet. Future water demands of Hydropower and Livestock will be unmet by 27.47 and 1.41 % respectively. However, future domestic water use will have no shortage. This calls for planning of current and future surface water use in the upper Pangani River Basin.

Onset and demise of Cretaceous oceanic anoxic events: The coupling of surface and bottom oceanic processes in two pelagic basins of the western Tethys

NASA Astrophysics Data System (ADS)

Gambacorta, G.; Bersezio, R.; Weissert, H.; Erba, E.

2016-06-01

The upper Albian-lower Turonian pelagic successions of the Tethys record processes acting during the onset, core, and recovery from perturbed conditions across oceanic anoxic event (OAE) 1d, OAE 2, and the mid-Cenomanian event I (MCE I) relative to intervening intervals. Five sections from Umbria-Marche and Belluno Basins (Italy) were analyzed at high resolution to assess processes in surface and deep waters. Recurrent facies stacking patterns (SP) and their associations record periods of bottom current activity coupled with surface changes in trophic level. Climate changes appear to have been influential on deep circulation dynamics. Under greenhouse conditions, vigorous bottom currents were arguably induced by warm and dense saline deep waters originated on tropical shelves in the Tethys and/or proto-Atlantic Ocean. Tractive facies postdating intermittent anoxia during OAE 1d and in the interval bracketed by MCE I and OAE 2 are indicative of feeble bottom currents, though capable of disrupting stratification and replenish deep water with oxygen. The major warming at the onset of OAE 2 might have enhanced the formation of warm salty waters, possibly producing local hiatuses at the base of the Bonarelli Level and winnowing at the seafloor. Hiatuses detected at the top of the Bonarelli Level possibly resulted from most effective bottom currents during the early Turonian thermal maximum. Times of minimal sediment displacement correlate with cooler climatic conditions and testify a different mechanism of deep water formation, as further suggested by a color change to reddish lithologies of the post-OAE 1d and post-OAE 2 intervals.

Ultrafast Hydration Dynamics and Coupled Water-Protein Fluctuations in Apomyoglobin

NASA Astrophysics Data System (ADS)

Yang, Yi; Zhang, Luyuan; Wang, Lijuan; Zhong, Dongping

2009-06-01

Protein hydration dynamics are of fundamental importance to its structure and function. Here, we characterize the global solvation dynamics and anisotropy dynamics around the apomyoglobin surface in different conformational states (native and molten globule) by measuring the Stokes shift and anisotropy decay of tryptophan with femtosecond-resolved fluorescence upconversion. With site-directed mutagenesis, we designed sixteen mutants with one tryptophan in each, and placed the probe at a desirable position ranging from buried in the protein core to fully solvent-exposed on the protein surface. In all protein sites studied, two distinct solvation relaxations (1-8 ps and 20-200 ps) were observed, reflecting the initial collective water relaxation and subsequent hydrogen-bond network restructuring, respectively, and both are strongly correlated with protein's local structures and chemical properties. The hydration dynamics of the mutants in molten globule state are faster than those observed in native state, indicating that the protein becomes more flexible and less structured when its conformation is converted from fully-folded native state to partially-folded molten globule state. Complementary, fluorescence anisotropy dynamics of all mutants in native state show an increasing trend of wobbling times (40-260 ps) when the location of the probe is changed from a loop, to a lateral helix, and then, to the compact protein core. Such an increase in wobbling times is related to the local protein structural rigidity, which relates the interaction of water with side chains. The ultrafast hydration dynamics and related side-chain motion around the protein surface unravel the coupled water-protein fluctuations on the picosecond time scales and indicate that the local protein motions are slaved by hydrating water fluctuations.

Aqueous aerosol SOA formation: impact on aerosol physical properties.

PubMed

Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

2013-01-01

Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions.

Influences of Coupled Hydrologic and Microbial Processes on River Corridor Biogeochemistry and Ecology

NASA Astrophysics Data System (ADS)

Scheibe, T. D.; Song, H. S.; Stegen, J.; Graham, E.; Bao, J.; Goldman, A.; Zhou, T.; Crump, A.; Hou, Z.; Hammond, G. E.; Chen, X.; Huang, M.; Zhang, X.; Nelson, W. C.; Garayburu-Caruso, V. A.

2017-12-01

The exchange of water between rivers and surrounding subsurface environments (hydrologic exchange flows or HEFs) is a vital aspect of river ecology and watershed function. HEFs play a key role in water quality, nutrient cycling, and ecosystem health, and they modulate water temperatures and enhance exchange of terrestrial and aquatic nutrients, which lead to elevated biogeochemical activity. However, these coupled hydrologic and microbiological processes are not well understood, particularly in the context of large managed river systems with highly variable discharge, and are poorly represented in system-scale quantitative models. Using the 75 km Hanford Reach of the Columbia River as the research domain, we apply high-resolution flow simulations supported by field observations to understand how variable river discharge interacts with hydromorphic and hydrogeologic structures to generate HEFs and distributions of subsurface residence times. We combine this understanding of hydrologic processes with microbiological activity measurements and reactive transport models to elucidate the holistic impacts of variable discharge on river corridor (surface and subsurface) ecosystems. In particular, our project seeks to develop and test new conceptual and numerical models that explicitly incorporate i) the character (chemical speciation and thermodynamics) of natural organic matter as it varies along flow paths and through mixing of groundwater and surface water, and ii) the history-dependent response of microbial communities to varying time scales of inundation associated with fluctuations in river discharge. The results of these high-resolution mechanistic models are guiding formulation and parameterization of reduced-order models applicable at reach to watershed scales. New understanding of coupled hydrology and microbiology in the river corridor will play a key role in reduction of uncertainties associated with major Earth system biogeochemical fluxes, improving predictions of environmental and human impacts on water quality and riverine ecosystems, and supporting environmentally responsible management of linked energy-water systems.

Project Work Plan: Sequestration of Strontium-90 Subsurface Contamination in the Hanford 100-N Area by Surface Infiltration of an Apatite Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szecsody, Jim E.

2006-04-30

We propose to develop an infiltration strategy that defines the precipitation rate of an apatite-forming solution and Sr-90 sequestration processes under variably saturated (low water content) conditions. We will develop this understanding through small-scale column studies, intermediate-scale two-dimensional (2-D) experiments, and numerical modeling to quantify individual and coupled processes associated with apatite formation and Sr-90 transport during and after infiltration of the Ca-citrate-PO4 solution. Development of capabilities to simulate these coupled biogeochemical processes during both injection and infiltration will be used to determine the most cost-effective means to emplace an in situ apatite barrier with a longevity of 300 yearsmore » to permanently sequester Sr-90 until it decays. Biogeochemical processes that will be investigated are citrate biodegradation and apatite precipitation rates at varying water contents as a function of water content. Coupled processes that will be investigated include the influence of apatite precipitation (which occupies pore space) on the hydraulic and transport properties of the porous media during infiltration.« less

Simulating land-atmosphere feedbacks and response to widespread forest disturbance: The role of lower boundary configuration and dynamic water table in meteorological modeling

NASA Astrophysics Data System (ADS)

Forrester, M.; Maxwell, R. M.; Bearup, L. A.; Gochis, D.

2017-12-01

Numerical meteorological models are frequently used to diagnose land-atmosphere interactions and predict large-scale response to extreme or hazardous events, including widespread land disturbance or perturbations to near-surface moisture. However, few atmospheric modeling platforms consider the impact that dynamic groundwater storage, specifically 3D subsurface flow, has on land-atmosphere interactions. In this study, we use the Weather Research and Forecasting (WRF) mesoscale meteorological model to identify ecohydrologic and land-atmosphere feedbacks to disturbance by the mountain pine beetle (MPB) over the Colorado Headwaters region. Disturbance simulations are applied to WRF with various lower boundary configurations: Including default Noah land surface model soil moisture representation; a version of WRF coupled to ParFlow (PF), an integrated groundwater-surface water model that resolves variably saturated flow in the subsurface; and WRF coupled to PF in a static water table version, simulating only vertical and no lateral subsurface flow. Our results agree with previous literature showing MPB-induced reductions in canopy transpiration in all lower boundary scenarios, as well as energy repartitioning, higher water tables, and higher planetary boundary layer over infested regions. Simulations show that expanding from local to watershed scale results in significant damping of MPB signal as unforested and unimpacted regions are added; and, while deforestation appears to have secondary feedbacks to planetary boundary layer and convection, these slight perturbations to cumulative summer precipitation are insignificant in the context of ensemble methodologies. Notably, the results suggest that groundwater representation in atmospheric modeling affects the response intensity of a land disturbance event. In the WRF-PF case, energy and atmospheric processes are more sensitive to disturbance in regions with higher water tables. Also, when dynamic subsurface hydrology is removed, WRF simulates a greater response to MPB at the land-atmosphere interface, including greater changes to daytime skin temperature, Bowen ratio and near-surface humidity. These findings highlight lower boundary representations in computational meteorology and numerical land-atmosphere modeling.

The influence of water table depth and the free atmospheric state on convective rainfall predisposition

DOE PAGES

Bonetti, Sara; Manoli, Gabriele; Domec, Jean-Christophe; ...

2015-03-16

Here, we report a mechanistic model for the soil-plant system is coupled to a conventional slab representation of the atmospheric boundary layer (ABL) to explore the role of groundwater table (WT) variations and free atmospheric (FA) states on convective rainfall predisposition (CRP) at a Loblolly pine plantation site situated in the lower coastal plain of North Carolina. Predisposition is quantified using the crossing between modeled lifting condensation level (LCL) and convectively grown ABL depth. The LCL-ABL depth crossing is necessary for air saturation but not sufficient for cloud formation and subsequent convective rainfall occurrence. However, such crossing forms the mainmore » template for which all subsequent dynamical processes regulating the formation (or suppression) of convective rainfall operate on. If the feedback between surface fluxes and FA conditions is neglected, a reduction in latent heat flux associated with reduced WT levels is shown to enhance the ABL-LCL crossing probability. When the soil-plant system is fully coupled with ABL dynamics thereby allowing feedback with ABL temperature and humidity, FA states remain the leading control on CRP. However, vegetation water stress plays a role in controlling ABL-LCL crossing when the humidity supply by the FA is within an intermediate range of values. When FA humidity supply is low, cloud formation is suppressed independent of surface latent heat flux. Similarly, when FA moisture supply is high, cloud formation can occur independent of surface latent heat flux. In an intermediate regime of FA moisture supply, the surface latent heat flux controlled by soil water availability can supplement (or suppress) the necessary water vapor leading to reduced LCL and subsequent ABL-LCL crossing. Lastly, it is shown that this intermediate state corresponds to FA values around the mode in observed humidity lapse rates γ w (between -2.5 × 10 -6 and -1.5 × 10 -6 kg kg -1m -1), suggesting that vegetation water uptake may be controlling CRP at the study site.« less

Response to Memorandum by Rowley and Dixon Regarding U.S. Geological Survey Report Titled Characterization of Surface-Water Resources in the Great Basin National Park Area and Their Susceptibility to Ground-Water Withdrawals in Adjacent Valleys, White Pine County, Nevada

DTIC Science & Technology

2006-01-01

several faults. Declines of more than 50 feet were observed at wells near Marigold mine and a couple of miles closer to Lone Tree mine. The observed...Ground-water declines at Marigold mine are of particular interest because seldom do hydrologists have streamflow and ground-water data in the...Land Management, 2003, Final supplemental environmental impact statement, Glamis Marigold Mining Company’s millennium expansion project: Bureau of Land

Nutrient and salt mass balance on the Lower Arkansas River and a contributing tributary in an irrigated agricultural setting

Treesearch

Alexander Hulzenga; Ryan T. Bailey; Timothy K. Gates

2016-01-01

The Lower Arkansas River Basin is an irrigated, agricultural valley suffering from high concentrations of nutrients and salts in the coupled groundwater-surface water system. The majority of water quality data collection and associated spatial analysis of concentrations and mass loadings from the aquifer to the stream network has been performed at the regional scale (...

How does rapidly changing discharge during storm events affect transient storage and channel water balance in a headwater mountain stream?

Treesearch

Adam S. Ward; Michael N. Gooseff; Thomas J. Voltz; Michael Fitzgerald; Kamini Singha; Jay P. Zarnetske

2013-01-01

Measurements of transient storage in coupled surface-water and groundwater systems are widely made during base flow periods and rarely made during storm flow periods. We completed 24 sets of slug injections in three contiguous study reaches during a 1.25 year return interval storm event (discharge ranging from 21.5 to 434 L s1 ) in a net gaining headwater stream within...

User guide for the farm process (FMP1) for the U.S. Geological Survey's modular three-dimensional finite-difference ground-water flow model, MODFLOW-2000

USGS Publications Warehouse

Schmid, Wolfgang; Hanson, R.T.; Maddock, Thomas; Leake, S.A.

2006-01-01

There is a need to estimate dynamically integrated supply-and-demand components of irrigated agriculture as part of the simulation of surface-water and ground-water flow. To meet this need, a computer program called the Farm Process (FMP1) was developed for the U.S. Geological Survey three-dimensional finite-difference modular ground-water flow model, MODFLOW- 2000 (MF2K). The FMP1 allows MF2K users to simulate conjunctive use of surface- and ground water for irrigated agriculture for historical and future simulations, water-rights issues and operational decisions, nondrought and drought scenarios. By dynamically integrating farm delivery requirement, surface- and ground-water delivery, as well as irrigation-return flow, the FMP1 allows for the estimation of supplemental well pumpage. While farm delivery requirement and irrigation return flow are simulated by the FMP1, the surface-water delivery to the farm can be simulated optionally by coupling the FMP1 with the Streamflow Routing Package (SFR1) and the farm well pumping can be simulated optionally by coupling the FMP1 to the Multi-Node Well (MNW) Package. In addition, semi-routed deliveries can be specified that are associated with points of diversion in the SFR1 stream network. Nonrouted surface-water deliveries can be specified independently of any stream network. The FMP1 maintains a dual mass balance of a farm budget and as part of the ground-water budget. Irrigation demand, supply, and return flow are in part subject to head-dependent sources and sinks such as evapotranspiration from ground water and leakage between the conveyance system and the aquifer. Farm well discharge and farm net recharge are source/sink terms in the FMP1, which depend on transpiration uptake from ground water and other head dependent consumptive use components. For heads rising above the bottom of the root zone, the actual transpiration is taken to vary proportionally with the depth of the active root zone, which can be restricted by anoxia or wilting. Depths corresponding to anoxia- or wilting-related pressure heads within the root zone are found using analytical solutions of a vertical pseudo steady-state pressure- head distribution over the depth of the total root zone (Consumptive Use Concept 1). Alternatively, a simpler, conceptual model is available, which defines how consumptive use (CU) components vary with changing head (CU Concept 2). Subtracting the ground water and precipitation transpiration components from the total transpiration yields a transpiratory irrigation requirement for each cell. The total farm delivery requirement (TFDR) then is determined as cumulative transpiratory and evaporative irrigation requirements of all farm cells and increased sufficiently to compensate for inefficient use from irrigation with respect to plant consumption. The TFDR subsequently is satisfied with surface- and ground-water delivery, respectively constrained by allotments, water rights, or maximum capacities. Five economic and noneconomic drought response policies can be applied optionally, if the potential supply of surface water and ground water is insufficient to meet the crop demand: acreage-optimization with or without a water conservation pool, deficit irrigation with or without water-stacking, and zero policy.

Surface hydration amplifies single-well protein atom diffusion propagating into the macromolecular core

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Liang; Cheng, Xiaolin; Glass, Dennis C.

2012-06-05

The effect of surface hydration water on internal protein motion is of fundamental interest in molecular biophysics. Here, by decomposing the picosecond to nanosecond atomic motion in molecular dynamics simulations of lysozyme at different hydration levels into three components localized single-well diffusion, methyl group rotation, and nonmethyl jumps we show that the effect of surface hydration is mainly to increase the volume of the localized single-well diffusion. As a result, these diffusive motions are coupled in such a way that the hydration effect propagates from the protein surface into the dry core.

Understanding Water-Energy-Ecology Nexus from an Integrated Earth-Human System Perspective

NASA Astrophysics Data System (ADS)

Li, H. Y.; Zhang, X.; Wan, W.; Zhuang, Y.; Hejazi, M. I.; Leung, L. R.

2017-12-01

Both Earth and human systems exert notable controls on streamflow and stream temperature that influence energy production and ecosystem health. An integrated water model representing river processes and reservoir regulations has been developed and coupled to a land surface model and an integrated assessment model of energy, land, water, and socioeconomics to investigate the energy-water-ecology nexus in the context of climate change and water management. Simulations driven by two climate change projections following the RCP 4.5 and RCP 8.5 radiative forcing scenarios, with and without water management, are analyzed to evaluate the individual and combined effects of climate change and water management on streamflow and stream temperature in the U.S. The simulations revealed important impacts of climate change and water management on hydrological droughts. The simulations also revealed the dynamics of competition between changes in water demand and water availability in the RCP 4.5 and RCP 8.5 scenarios that influence streamflow and stream temperature, with important consequences to thermoelectricity production and future survival of juvenile Salmon. The integrated water model is being implemented to the Accelerated Climate Modeling for Energy (ACME), a coupled Earth System Model, to enable future investigations of the energy-water-ecology nexus in the integrated Earth-Human system.

Using an Integrated Surface Water - Groundwater Flow Model for Evaluating the Hydrologic Impacts of Historic and Potential Future Dry Periods on Simulated Water Budgets in the Santa Rosa Plain Watershed, Northern California, USA

NASA Astrophysics Data System (ADS)

Hevesi, J. A.; Woolfenden, L. R.; Nishikawa, T.

2014-12-01

Communities in the Santa Rosa Plain watershed (SRPW), Sonoma County, CA, USA are experiencing increasing demand for limited water resources. Streamflow in the SRPW is runoff dominated; however, groundwater also is an important resource in the basin. The watershed has an area of 262 mi2 that includes natural, agricultural, and urban land uses. To evaluate the hydrologic system, an integrated hydrologic model was developed using the U.S. Geological Survey coupled groundwater and surface-water flow model, GSFLOW. The model uses a daily time step and a grid-based discretization of the SRPW consisting of 16,741 10-acre cells for 8 model layers to simulate all water budget components of the surface and subsurface hydrologic system. Simulation results indicate significant impacts on streamflow and recharge in response to the below average precipitation during the dry periods. The recharge and streamflow distributions simulated for historic dry periods were compared to future dry periods projected from 4 GCM realizations (two different GCMs and two different CO2 forcing scenarios) for the 21st century, with the dry periods defined as 3 consecutive years of below average precipitation. For many of the projected dry periods, the decreases in recharge and streamflow were greater than for the historic dry periods due to a combination of lower precipitation and increases in simulated evapotranspiration for the warmer 21st century projected by the GCM realizations. The greatest impact on streamflow for both historic and projected future dry periods is the diminished baseflow from late spring to early fall, with an increase in the percentage of intermittent and dry stream reaches. The results indicate that the coupled model is a useful tool for water managers to better understand the potential effects of future dry periods on spatially and temporally distributed streamflow and recharge, as well as other components of the water budget.

A regional coupled surface water/groundwater model of the Okavango Delta, Botswana

NASA Astrophysics Data System (ADS)

Bauer, Peter; Gumbricht, Thomas; Kinzelbach, Wolfgang

2006-04-01

In the endorheic Okavango River system in southern Africa a balance between human and environmental water demands has to be achieved. The runoff generated in the humid tropical highlands of Angola flows through arid Namibia and Botswana before forming a large inland delta and eventually being consumed by evapotranspiration. With an approximate size of about 30,000 km2, the Okavango Delta is the world's largest site protected under the convention on wetlands of international importance, signed in 1971 in Ramsar, Iran. The extended wetlands of the Okavango Delta, which sustain a rich ecology, spectacular wildlife, and a first-class tourism infrastructure, depend on the combined effect of the highly seasonal runoff in the Okavango River and variable local climate. The annual fluctuations in the inflow are transformed into vast areas of seasonally inundated floodplains. Water abstraction and reservoir building in the upstream countries are expected to reduce and/or redistribute the available flows for the Okavango Delta ecosystem. To study the impacts of upstream and local interventions, a large-scale (1 km2 grid), coupled surface water/groundwater model has been developed. It is composed of a surface water flow component based on the diffusive wave approximation of the Saint-Venant equations, a groundwater component, and a relatively simple vadose zone component for calculating the net water exchange between land and atmosphere. The numerical scheme is based on the groundwater simulation software MODFLOW-96. Since the primary model output is the spatiotemporal distribution of flooded areas and since hydrologic data on the large and inaccessible floodplains and tributaries are sparse and unreliable, the model was not calibrated with point hydrographs but with a time series of flooding patterns derived from satellite imagery (NOAA advanced very high resolution radiometer). Scenarios were designed to study major upstream and local interventions and their expected impacts in the Delta. The scenarios' results can help decision makers strike a balance between environmental and human water demands in the basin.

Simulating root-induced rhizosphere deformation and its effect on water flow

NASA Astrophysics Data System (ADS)

Aravena, J. E.; Ruiz, S.; Mandava, A.; Regentova, E. E.; Ghezzehei, T.; Berli, M.; Tyler, S. W.

2011-12-01

Soil structure in the rhizosphere is influenced by root activities, such as mucilage production, microbial activity and root growth. Root growth alters soil structure by moving and deforming soil aggregates, affecting water and nutrient flow from the bulk soil to the root surface. In this study, we utilized synchrotron X-ray micro-tomography (XMT) and finite element analysis to quantify the effect of root-induced compaction on water flow through the rhizosphere to the root surface. In a first step, finite element meshes of structured soil around the root were created by processing rhizosphere XMT images. Then, soil deformation by root expansion was simulated using COMSOL Multiphysics° (Version 4.2) considering the soil an elasto-plastic porous material. Finally, fluid flow simulations were carried out on the deformed mesh to quantify the effect of root-induced compaction on water flow to the root surface. We found a 31% increase in water flow from the bulk soil to the root due to a 56% increase in root diameter. Simulations also show that the increase of root-soil contact area was the dominating factor with respect to the calculated increase in water flow. Increase of inter-aggregate contacts in size and number were observed within a couple of root diameters away from the root surface. But their influence on water flow was, in this case, rather limited compared to the immediate soil-root contact.

A Digital Map From External Forcing to the Final Surface Warming Pattern and its Seasonal Cycle

NASA Astrophysics Data System (ADS)

Cai, M.

2015-12-01

Historically, only the thermodynamic processes (e.g., water vapor, cloud, surface albedo, and atmospheric lapse rate) that directly influence the top of the atmosphere (TOA) radiative energy flux balance are considered in climate feedback analysis. One of my recent research areas is to develop a new framework for climate feedback analysis that explicitly takes into consideration not only the thermodynamic processes that the directly influence the TOA radiative energy flux balance but also the local dynamical (e.g., evaporation, surface sensible heat flux, vertical convections etc) and non-local dynamical (large-scale horizontal energy transport) processes in aiming to explain the warming asymmetry between high and low latitudes, between ocean and land, and between the surface and atmosphere. In the last 5-6 years, we have developed a coupled atmosphere-surface climate feedback-response analysis method (CFRAM) as a new framework for estimating climate feedback and sensitivity in coupled general circulation models with a full physical parameterization package. In the CFRAM, the isolation of partial temperature changes due to an external forcing alone or an individual feedback is achieved by solving the linearized infrared radiation transfer model subject to individual energy flux perturbations (external or due to feedbacks). The partial temperature changes are addable and their sum is equal to the (total) temperature change (in the linear sense). The CFRAM is used to isolate the partial temperature changes due to the external forcing, due to water vapor feedback, clouds, surface albedo, local vertical convection, and non-local atmospheric dynamical feedbacks, as well as oceanic heat storage. It has been shown that seasonal variations in the cloud feedback, surface albedo feedback, and ocean heat storage/dynamics feedback, directly caused by the strong annual cycle of insolation, contribute primarily to the large seasonal variation of polar warming. Furthermore, the CO2 forcing, and water vapor and atmospheric dynamics feedbacks add to the maximum polar warming in fall/winter.

Adaptive resolution simulation of an atomistic protein in MARTINI water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zavadlav, Julija; Melo, Manuel Nuno; Marrink, Siewert J., E-mail: s.j.marrink@rug.nl

2014-02-07

We present an adaptive resolution simulation of protein G in multiscale water. We couple atomistic water around the protein with mesoscopic water, where four water molecules are represented with one coarse-grained bead, farther away. We circumvent the difficulties that arise from coupling to the coarse-grained model via a 4-to-1 molecule coarse-grain mapping by using bundled water models, i.e., we restrict the relative movement of water molecules that are mapped to the same coarse-grained bead employing harmonic springs. The water molecules change their resolution from four molecules to one coarse-grained particle and vice versa adaptively on-the-fly. Having performed 15 ns long molecularmore » dynamics simulations, we observe within our error bars no differences between structural (e.g., root-mean-squared deviation and fluctuations of backbone atoms, radius of gyration, the stability of native contacts and secondary structure, and the solvent accessible surface area) and dynamical properties of the protein in the adaptive resolution approach compared to the fully atomistically solvated model. Our multiscale model is compatible with the widely used MARTINI force field and will therefore significantly enhance the scope of biomolecular simulations.« less

Adaptive resolution simulation of an atomistic protein in MARTINI water.

PubMed

Zavadlav, Julija; Melo, Manuel Nuno; Marrink, Siewert J; Praprotnik, Matej

2014-02-07

We present an adaptive resolution simulation of protein G in multiscale water. We couple atomistic water around the protein with mesoscopic water, where four water molecules are represented with one coarse-grained bead, farther away. We circumvent the difficulties that arise from coupling to the coarse-grained model via a 4-to-1 molecule coarse-grain mapping by using bundled water models, i.e., we restrict the relative movement of water molecules that are mapped to the same coarse-grained bead employing harmonic springs. The water molecules change their resolution from four molecules to one coarse-grained particle and vice versa adaptively on-the-fly. Having performed 15 ns long molecular dynamics simulations, we observe within our error bars no differences between structural (e.g., root-mean-squared deviation and fluctuations of backbone atoms, radius of gyration, the stability of native contacts and secondary structure, and the solvent accessible surface area) and dynamical properties of the protein in the adaptive resolution approach compared to the fully atomistically solvated model. Our multiscale model is compatible with the widely used MARTINI force field and will therefore significantly enhance the scope of biomolecular simulations.

Water resources during drought conditions and postfire water quality in the upper Rio Hondo Basin, Lincoln County, New Mexico, 2010-13

USGS Publications Warehouse

Sherson, Lauren R.; Rice, Steven E.

2015-07-16

Changes in climate and increased groundwater and surface-water use are likely to affect the availability of water in the upper Rio Hondo Basin. Increased drought probably will increase the potential for wildfires, which can affect downstream water quality and increase flood potential. Climate-research predicted decreases in winter precipitation may have an adverse effect on the amount of groundwater recharge that occurs in the upper Rio Hondo Basin, given the predominance of winter precipitation recharge as indicated by the stable isotope results. Decreases in surface-water supplies because of persistent drought conditions and reductions in the quality of water because of the effects of wildfire may lead to a larger reliance on groundwater reserves in the upper Rio Hondo Basin. Decreasing water levels because of increasing groundwater withdrawal could reduce base flows in the Rio Bonito and Rio Ruidoso. Well organized and scientifically supported regional water-resources management will be necessary for dealing with the likely scenario of increases in demand coupled with decreases in supply in the upper Rio Hondo Basin.

Hindcast of water availability in regional aquifer systems using MODFLOW Farm Process

USGS Publications Warehouse

Schmid, Wolfgang; Hanson, Randall T.; Faunt, Claudia C.; Phillips, Steven P.

2015-01-01

Coupled groundwater and surface-water components of the hydrologic cycle can be simulated by the Farm Process for MODFLOW (MF-FMP) in both irrigated and non-irrigated areas and aquifer-storage and recovery systems. MF-FMP is being applied to three productive agricultural regions of different scale in the State of California, USA, to assess the availability of water and the impacts of alternative management decisions. Hindcast simulations are conducted for similar periods from the 1960s to near recent times. Historical groundwater pumpage is mostly unknown in one region (Central Valley) and is estimated by MF-FMP. In another region (Pajaro Valley), recorded pumpage is used to calibrate model-estimated pumpage. Multiple types of observations are used to estimate uncertain parameters, such as hydraulic, land-use, and farm properties. MF-FMP simulates how climate variability and water-import availability affect water demand and supply. MF-FMP can be used to predict water availability based on anticipated changes in anthropogenic or natural water demands. Keywords groundwater; surface-water; irrigation; water availability; response to climate variability/change

Comparing Noah-MP simulations of energy and water fluxes in the soil-vegetation-atmosphere continuum with plot scale measurements

NASA Astrophysics Data System (ADS)

Gayler, Sebastian; Wöhling, Thomas; Högy, Petra; Ingwersen, Joachim; Wizemann, Hans-Dieter; Wulfmeyer, Volker; Streck, Thilo

2013-04-01

During the last years, land-surface models have proven to perform well in several studies that compared simulated fluxes of water and energy from the land surface to the atmosphere against measured fluxes at the plot-scale. In contrast, considerable deficits of land-surface models have been identified to simulate soil water fluxes and vertical soil moisture distribution. For example, Gayler et al. (2013) showed that simplifications in the representation of root water uptake can result in insufficient simulations of the vertical distribution of soil moisture and its dynamics. However, in coupled simulations of the terrestrial water cycle, both sub-systems, the atmosphere and the subsurface hydrogeo-system, must fit together and models are needed, which are able to adequately simulate soil moisture, latent heat flux, and their interrelationship. Consequently, land-surface models must be further improved, e.g. by incorporation of advanced biogeophysics models. To improve the conceptual realism in biophysical and hydrological processes in the community land surface model Noah, this model was recently enhanced to Noah-MP by a multi-options framework to parameterize individual processes (Niu et al., 2011). Thus, in Noah-MP the user can choose from several alternative models for vegetation and hydrology processes that can be applied in different combinations. In this study, we evaluate the performance of different Noah-MP model settings to simulate water and energy fluxes across the land surface at two contrasting field sites in South-West Germany. The evaluation is done in 1D offline-mode, i.e. without coupling to an atmospheric model. The atmospheric forcing is provided by measured time series of the relevant variables. Simulation results are compared with eddy covariance measurements of turbulent fluxes and measured time series of soil moisture at different depths. The aims of the study are i) to carve out the most appropriate combination of process parameterizations in Noah-MP to simultaneously match the different components of the water and energy cycle at the field sites under consideration, and ii) to estimate the uncertainty in model structure. We further investigate the potential to improve simulation results by incorporating concepts of more advanced root water uptake models from agricultural field scale models into the land-surface-scheme. Gayler S, Ingwersen J, Priesack E, Wöhling T, Wulfmeyer V, Streck T (2013): Assessing the relevance of sub surface processes for the simulation of evapotranspiration and soil moisture dynamics with CLM3.5: Comparison with field data and crop model simulations. Environ. Earth Sci., 69(2), under revision. Niu G-Y, Yang Z-L, Mitchell KE, Chen F, Ek MB, Barlage M, Kumar A, Manning K, Niyogi D, Rosero E, Tewari M and Xia Y (2011): The community Noah land surface model with multiparameterization options (Noah-MP): 1. Model description and evaluation with local-scale measurements. Journal of Geophysical Research 116(D12109).

Experimental and numerical modelling of surface water-groundwater flow and pollution interactions under tidal forcing

NASA Astrophysics Data System (ADS)

Spanoudaki, Katerina; Bockelmann-Evans, Bettina; Schaefer, Florian; Kampanis, Nikolaos; Nanou-Giannarou, Aikaterini; Stamou, Anastasios; Falconer, Roger

2015-04-01

Surface water and groundwater are integral components of the hydrologic continuum and the interaction between them affects both their quantity and quality. However, surface water and groundwater are often considered as two separate systems and are analysed independently. This separation is partly due to the different time scales, which apply in surface water and groundwater flows and partly due to the difficulties in measuring and modelling their interactions (Winter et al., 1998). Coastal areas in particular are a difficult hydrologic environment to represent with a mathematical model due to the large number of contributing hydrologic processes. Accurate prediction of interactions between coastal waters, groundwater and neighbouring wetlands, for example, requires the use of integrated surface water-groundwater models. In the past few decades a large number of mathematical models and field methods have been developed in order to quantify the interaction between groundwater and hydraulically connected surface water bodies. Field studies may provide the best data (Hughes, 1995) but are usually expensive and involve too many parameters. In addition, the interpretation of field measurements and linking with modelling tools often proves to be difficult. In contrast, experimental studies are less expensive and provide controlled data. However, experimental studies of surface water-groundwater interaction are less frequently encountered in the literature than filed studies (e.g. Ebrahimi et al., 2007; Kuan et al., 2012; Sparks et al., 2013). To this end, an experimental model has been constructed at the Hyder Hydraulics Laboratory at Cardiff University to enable measurements to be made of groundwater transport through a sand embankment between a tidal water body such as an estuary and a non-tidal water body such as a wetland. The transport behaviour of a conservative tracer was studied for a constant water level on the wetland side of the embankment, while running a continuous tide on the coastal side. The integrated surface water-groundwater numerical model IRENE (Spanoudaki et al., 2009, Spanoudaki, 2010) was also used in the study, with the numerical model predictions being compared with experimental results, which provide a valuable database for model calibration and validation. IRENE couples the 3D, non-steady state Navier-Stokes equations, after Reynolds averaging and with the assumption of hydrostatic pressure distribution, to the equations describing 3D saturated groundwater flow of constant density. The model uses the finite volume method with a cell-centered structured grid providing thus flexibility and accuracy in simulating irregular boundary geometries. A semi-implicit finite difference scheme is used to solve the surface water flow equations, while a fully implicit finite difference scheme is used for the groundwater equations. Pollution interactions are simulated by coupling the advection-diffusion equation describing the fate and transport of contaminants introduced in a 3D turbulent flow field to the partial differential equation describing the fate and transport of contaminants in 3D transient groundwater flow systems. References Ebrahimi, K., Falconer, R.A. and Lin B. (2007). Flow and solute fluxes in integrated wetland and coastal systems. Environmental Modelling and Software, 22 (9), 1337-1348. Hughes, S.A. (1995). Physical Modelling and Laboratory Techniques in Coastal Engineering. World Scientific Publishing Co. Pte. Ltd., Singapore. Kuan, W.K., Jin, G., Xin, P., Robinson, C. Gibbes, B. and Li. L. (2012). Tidal influence on seawater intrusion in unconfined coastal aquifers. Water Resources Research, 48 (2), doi:10.1029/2011WR010678. Spanoudaki, K., Stamou, A.I. and Nanou-Giannarou, A. (2009). Development and verification of a 3-D integrated surface water-groundwater model. Journal of Hydrology, 375 (3-4), 410-427. Spanoudaki, K. (2010). Integrated numerical modelling of surface water groundwater systems (in Greek). Ph.D. Thesis, National Technical University of Athens, Greece. Sparks, T. D., Bockelmann-Evans, B. N. and Falconer, R. A. (2013). Laboratory Validation of an Integrated Surface Water- Groundwater Model. Journal of Water Resource and Protection, 5, 377-394. Winter, T.C., Harvey, J.W., Franke, O.L. and Alley, W.M., 1998. Groundwater and surface water - A single resource. USGS, Circular 1139.

Sulfur mass-independent fractionation in subsurface fracture waters indicates a long-standing sulfur cycle in Precambrian rocks

PubMed Central

Li, L.; Wing, B. A.; Bui, T. H.; McDermott, J. M.; Slater, G. F.; Wei, S.; Lacrampe-Couloume, G.; Lollar, B. Sherwood

2016-01-01

The discovery of hydrogen-rich waters preserved below the Earth's surface in Precambrian rocks worldwide expands our understanding of the habitability of the terrestrial subsurface. Many deep microbial ecosystems in these waters survive by coupling hydrogen oxidation to sulfate reduction. Hydrogen originates from water–rock reactions including serpentinization and radiolytic decomposition of water induced by decay of radioactive elements in the host rocks. The origin of dissolved sulfate, however, remains unknown. Here we report, from anoxic saline fracture waters ∼2.4 km below surface in the Canadian Shield, a sulfur mass-independent fractionation signal in dissolved sulfate. We demonstrate that this sulfate most likely originates from oxidation of sulfide minerals in the Archaean host rocks through the action of dissolved oxidants (for example, HO· and H2O2) themselves derived from radiolysis of water, thereby providing a coherent long-term mechanism capable of supplying both an essential electron donor (H2) and a complementary acceptor (sulfate) for the deep biosphere. PMID:27807346

A new capture fraction method to map how pumpage affects surface water flow

USGS Publications Warehouse

Leake, S.A.; Reeves, H.W.; Dickinson, J.E.

2010-01-01

All groundwater pumped is balanced by removal of water somewhere, initially from storage in the aquifer and later from capture in the form of increase in recharge and decrease in discharge. Capture that results in a loss of water in streams, rivers, and wetlands now is a concern in many parts of the United States. Hydrologists commonly use analytical and numerical approaches to study temporal variations in sources of water to wells for select points of interest. Much can be learned about coupled surface/groundwater systems, however, by looking at the spatial distribution of theoretical capture for select times of interest. Development of maps of capture requires (1) a reasonably well-constructed transient or steady state model of an aquifer with head-dependent flow boundaries representing surface water features or evapotranspiration and (2) an automated procedure to run the model repeatedly and extract results, each time with a well in a different location. This paper presents new methods for simulating and mapping capture using three-dimensional groundwater flow models and presents examples from Arizona, Oregon, and Michigan. Journal compilation ?? 2010 National Ground Water Association. No claim to original US government works.

Comparative study of particle structure evolution during water sorption: skim and whole milk powders.

PubMed

Murrieta-Pazos, I; Gaiani, C; Galet, L; Cuq, B; Desobry, S; Scher, J

2011-10-01

Surface composition of dairy powders influences significantly a quantity of functional properties such as rehydration, caking, agglomeration. Nevertheless, the kinetic of water uptake by the powders was never directly related to the structure and the composition of the surface. In this work, the effect of relative humidity on the structural reorganization of two types of dairy powder was studied. The water-powder interaction for industrial whole milk powder, and skim milk powder was studied using dynamic vapor sorption. The water sorption isotherms were fitted with a Brunner-Emmet-Teller model and each stage of the sorption curve was analyzed with a Fickian diffusion. The water content in the monolayer predicted for each powder and the moisture diffusivity calculated were discussed and compared. Concurrently, powders microstructure and powders surface under variable relative humidity were assessed by X-ray photoelectron spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray and atomic force microscopy. A correlation between the data obtained from the sorption isotherms and the modifications of structure allowed us to conclude that powder microstructure and chemical state of the components could play an important role in determining the water diffusivity. Copyright © 2011 Elsevier B.V. All rights reserved.

Influence of swimsuit design and fabric surface properties on the butterfly kinematics.

PubMed

Rogowski, Isabelle; Monteil, Karine; Legreneur, Pierre; Lanteri, Pierre

2006-02-01

This study investigated the influence of the covering swimsuit and the fabric surface properties on the butterfly stroke kinematics. Surface properties were evaluated by wetting measurements of two fabric samples: one for training suits and one for competition suits. The surface of the second one was coated by mechanochemical treatment in order to modify its surface properties. Nine national level swimmers performed a 50-m butterfly at submaximal velocity in three swimsuit conditions: conventional, long, and coated long swimsuits. From video recording, the hip was digitized at the entry and exit of the swimmer's hand in order to calculate the duration, hip displacement, and hip linear velocity during underwater and recovery phases and during stroke. The results for wetting show that competition fabric was more water-repellent than training fabric, but both were isotropic. Moreover, the mechanochemical treatment increased water repellency and anisotropy. The swimming results indicated that, when compared to a conventional swimsuit, wearing a coated long swimsuit increased hip linear velocity during stroke, and particularly during the recovery phase which had a shorter duration. These results suggest that the covering swimsuit should be coupled with the water repellent and anisotropic properties of the fabric surface in order to improve swimming performance.

Hydrodynamics of soap films probed by two-particle microrheology

NASA Astrophysics Data System (ADS)

Prasad, Vikram; Weeks, Eric R.

2007-11-01

A soap film consists of a thin water layer that is separated from two bulk air phases above and below it by surfactant monolayers. The flow fields in the soap film created in response to a perturbation depend on coupling between these different phases, the exact nature of which is unknown. In order to determine this coupling, we use polystyrene spheres as tracer particles and track their diffusive motions in the soap film. The correlated Brownian motion of pairs of particles (two-particle microrheology) maps out the flow field, and provides a measure of the surface viscosity of the soap film as well. This measured surface viscosity agrees well with the value obtained from self diffusion of single particles (one-particle microrheology) in the film.

Coupling of Noah-MP and the High Resolution CI-WATER ADHydro Hydrological Model

NASA Astrophysics Data System (ADS)

Moreno, H. A.; Goncalves Pureza, L.; Ogden, F. L.; Steinke, R. C.

2014-12-01

ADHydro is a physics-based, high-resolution, distributed hydrological model suitable for simulating large watersheds in a massively parallel computing environment. It simulates important processes such as: rainfall and infiltration, snowfall and snowmelt in complex terrain, vegetation and evapotranspiration, soil heat flux and freezing, overland flow, channel flow, groundwater flow and water management. For the vegetation and evapotranspiration processes, ADHydro uses the validated community land surface model (LSM) Noah-MP. Noah-MP uses multiple options for key land-surface hydrology and was developed to facilitate climate predictions with physically based ensembles. This presentation discusses the lessons learned in coupling Noah-MP to ADHydro. Noah-MP is delivered with a main driver program and not as a library with a clear interface to be called from other codes. This required some investigation to determine the correct functions to call and the appropriate parameter values. ADHydro runs Noah-MP as a point process on each mesh element and provides initialization and forcing data for each element. Modeling data are acquired from various sources including the Soil Survey Geographic Database (SSURGO), the Weather Research and Forecasting (WRF) model, and internal ADHydro simulation states. Despite these challenges in coupling Noah-MP to ADHydro, the use of Noah-MP provides the benefits of a supported community code.

Synergistic prevention of biofouling in seawater desalination by zwitterionic surfaces and low-level chlorination.

PubMed

Yang, Rong; Jang, Hongchul; Stocker, Roman; Gleason, Karen K

2014-03-19

Smooth, durable, ultrathin antifouling layers are deposited onto commercial reverse osmosis membranes without damaging them and they exhibit a fouling reduction. A new synergistic approach to antifouling, by coupling surface modification and drinking-water-level chlorination is enabled by the films' unique resistance against chlorine degradation. This approach substantially enhances longer-term fouling resistance compared with surface modification or chlorination alone, and can reduce freshwater production cost and its collateral toxicity to marine biota. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of a regional air-quality model with bidirectional NH3 exchange coupled to an agroecosystem modelecosystem model

EPA Science Inventory

Atmospheric ammonia (NH₃) is the primary atmospheric base and an important precursor for inorganic particulate matter and when deposited NH₃ contributes to surface water eutrophication, soil acidification and decline in species biodiversity. Flux measurement...

PHOSPHORUS SORPTION DYNAMICS IN SOILS AND COUPLING WITH SURFACE AND PORE WATER IN RIVERINE WETLANDS

EPA Science Inventory

Adsorption to soils is one of the dominant mechanisms of P storage in wetlands. We examined P sorption dynamics in soils collected at 12 sample points with diverse hydrology, geomorphic position, mineralogy, and plant communities in two riverine wetlands in northern Minnesota and...

Development of a human-specific B. thetaiotaomicron IMS/ATP assay for measuring viable human contamination in surface waters in Baja California, Mexico

EPA Science Inventory

Immunomagnetic separation/adenosine triphosphate (IMS/ATP) assays utilize paramagnetic beads and target-specific antibodies to isolate target organisms. Following isolation, adenosine tri-phosphate (ATP) is extracted from the target population and quantified. An inversely-couple...

Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

NASA Astrophysics Data System (ADS)

Tian, Y.; Wu, B.; Zheng, Y.

2013-12-01

In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

Simulated variability of the Atlantic meridional overturning circulation

NASA Astrophysics Data System (ADS)

Bentsen, M.; Drange, H.; Furevik, T.; Zhou, T.

To examine the multi-annual to decadal scale variability of the Atlantic Meridional Overturning Circulation (AMOC) we conducted a four-member ensemble with a daily reanalysis forced, medium-resolution global version of the isopycnic coordinate ocean model MICOM, and a 300-years integration with the fully coupled Bergen Climate Model (BCM). The simulations of the AMOC with both model systems yield a long-term mean value of 18 Sv and decadal variability with an amplitude of 1-3 Sv. The power spectrum of the inter-annual to decadal scale variability of the AMOC in BCM generally follows the theoretical red noise spectrum, with indications of increased power near the 20-years period. Comparison with observational proxy indices for the AMOC, e.g. the thickness of the Labrador Sea Water, the strength of the baroclinic gyre circulation in the North Atlantic Ocean, and the surface temperature anomalies along the mean path of the Gulf Stream, shows similar trends and phasing of the variability, indicating that the simulated AMOC variability is robust and real. Mixing indices have been constructed for the Labrador, the Irminger and the Greenland-Iceland-Norwegian (GIN) seas. While convective mixing in the Labrador and the GIN seas are in opposite phase, and linked to the NAO as observations suggest, the convective mixing in the Irminger Sea is in phase with or leads the Labrador Sea. Newly formed deep water is seen as a slow, anomalous cold and fresh, plume flowing southward along the western continental slope of the Atlantic Ocean, with a return flow of warm and saline water on the surface. In addition, fast-travelling topographically trapped waves propagate southward along the continental slope towards equator, where they go east and continue along the eastern rim of the Atlantic. For both types of experiments, the Northern Hemisphere sea level pressure and 2 m temperature anomaly patterns computed based on the difference between climate states with strong and weak AMOC yields a NAO-like pattern with intensified Icelandic low and Azores high, and a warming of 0.25-0.5 °C of the central North Atlantic sea-surface temperature (SST). The reanalysis forced simulations indicate a coupling between the Labrador Sea Water production rate and an equatorial Atlantic SST index in accordance with observations. This coupling is not identified in the coupled simulation.

Assessing the effects of the Great Eastern China urbanization on the East Asian summer monsoon by coupling an urban canopy model with a Regional Climate Model

NASA Astrophysics Data System (ADS)

Liu, Z.; Xue, Y.; Liu, S.; Oleson, K. W.

2012-12-01

The urbanization causes one of the most significant land cover changes. Especially over the eastern China from Beijing to Shanghai, the great urbanization occurs during the past half century.It modifies the physical characteristics of land surface, including land surface albedo, surface roughness length and aerodynamicresistanceand thermodynamic conduction over land. All of these play very important role in regional climate change. Afteremploying several WRF/Urban models to tests land use and land cover change(LUCC) caused by urbanization in East Asia, we decided to introducea urban canopy submodule,the Community Land surface Model urban scheme(CLMU)to the WRF and coupled with the WRF-SSiB3 regional climate model. The CLMU and SSIB share the similar principal to treat the surface energy and water balances and aerodynamic resistance between land and atmosphere. In the urban module, the energy balances on the five surface conditions are considered separately: building roof, sun side building wall, shade side building wall, pervious land surface and impervious road. The surface turbulence calculation is based on Monin-Obukhov similarity theory. We have made further improvements for the urban module. Over each surface condition, a method to calculate sky view factor (SVF) is developed based on the physically process while most urban models simply provide an empirical value for SVF. Our approach along with other improvement in short and long wave radiation transfer improves the accuracy of long-wave and shortwave radiation processing over urban surface. The force-restore approximation is employed to calculate the temperature of each outer surfaces of building. The inner side temperature is used as the restore term and was assigned as a tuning constant. Based on the nature of the force-restore method and our tests, we decide to employ the air mean temperature of last 72 hours as a restore term, which substantially improve the surface energy balance. We evaluate the ability of the newly coupled model by two runs: one without and one with the urban canopy module. The coupled model is integrated from March through September, covering a summer monsoon season. The preliminary results show more significant urban heat island (UHI) effect over urban areas with the urban canopy model. The existence of the UHIs enhances the convection in lower atmosphere, affects the water vapor transportation and precipitation of the surrounding area, consistent with the phenomena that occur in urban areas. We further test the effect of urbanization on the monsoon by introducing two maps, one with and one without urbanization and the effect of the urbanization on the monsoon evolution and low level circulation will be discussed in the presentation.

DIN retention-transport through four hydrologically connected zones in a headwater catchment of the Upper Mississippi River

USGS Publications Warehouse

Triska, F.J.; Duff, J.H.; Sheibley, R.W.; Jackman, A.P.; Avanzino, R.J.

2007-01-01

Dissolved inorganic nitrogen (DIN) retention-transport through a headwater catchment was synthesized from studies encompassing four distinct hydrologic zones of the Shingobee River Headwaters near the origin of the Mississippi River. The hydrologic zones included: (1) hillslope ground water (ridge to bankside riparian); (2) alluvial riparian ground water; (3) ground water discharged through subchannel sediments (hyporheic zone); and (4) channel surface water. During subsurface hillslope transport through Zone 1, DIN, primarily nitrate, decreased from ???3 mg-N/l to <0.1 mg-N/l. Ambient seasonal nitrate:chloride ratios in hillslope flow paths indicated both dilution and biotic processing caused nitrate loss. Biologically available organic carbon controlled biotic nitrate retention during hillslope transport. In the alluvial riparian zone (Zone 2) biologically available organic carbon controlled nitrate depletion although processing of both ambient and amended nitrate was faster during the summer than winter. In the hyporheic zone (Zone 3) and stream surface water (Zone 4) DIN retention was primarily controlled by temperature. Perfusion core studies using hyporheic sediment indicated sufficient organic carbon in bed sediments to retain ground water DIN via coupled nitrification-denitrification. Numerical simulations of seasonal hyporheic sediment nitrification-denitrification rates from perfusion cores adequately predicted surface water ammonium but not nitrate when compared to 5 years of monthly field data (1989-93). Mass balance studies in stream surface water indicated proportionally higher summer than winter N retention. Watershed DIN retention was effective during summer under the current land use of intermittently grazed pasture. However, more intensive land use such as row crop agriculture would decrease nitrate retention efficiency and increase loads to surface water. Understanding DIN retention capacity throughout the system, including special channel features such as sloughs, wetlands and floodplains that provide surface water-ground water connectivity, will be required to develop effective nitrate management strategies. ?? 2007 American Water Resources Association.

Study of the Effect of Wind Speed on Evaporation from Soil Through Integrated Modeling of Atmospheric Boundary Layer and Shallow Subsurface

NASA Astrophysics Data System (ADS)

Smits, K. M.; Davarzani, H.; Illangasekare, T. H.

2012-12-01

The study of the interaction between the land and atmosphere is paramount to our understanding of many emerging problems to include climate change and the movement of green house gases such as possible leaking of sequestered CO2. Soil moisture distribution in the shallow subsurface becomes a critical factor in these problems. The heat and mass flux in the form of soil evaporation across the land surface couples the atmospheric boundary layer to the shallow subsurface. The coupling between land and the atmosphere leads to highly dynamic interactions between the porous media properties, transport processes and boundary conditions, resulting in dynamic evaporative behavior. However, the coupling at the land-atmospheric interface is rarely considered in most current models and their validation for practical applications. This is due to the complexity of the problem in field scenarios and the scarcity of field or laboratory data capable of testing and refining coupled energy and mass transfer theories. In most efforts to compute evaporation from soil, only indirect coupling is provided to characterize the interaction between non-isothermal multiphase flows under realistic atmospheric conditions even though heat and mass flux are controlled by the coupled dynamics of the land and the atmospheric boundary layer. In earlier drying modeling concepts, imposing evaporation flux (kinetic of relative humidity) and temperature as surface boundary condition is often needed. With the goal of improving our understanding of the land/atmospheric coupling, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model consists of the coupled equations of mass conservation for the liquid phase (water) and gas phase (water vapor and air) in porous medium with gas phase (water vapor and air) in free flow domain under non-isothermal, non-equilibrium conditions. The boundary conditions at the porous medium-free flow medium interface include dynamical, thermal and solutal equilibriums, and using the Beavers-Joseph slip boundary condition. What is unique about this model is that the evaporation rate and soil surface temperature conditions come directly from the model output. In order to experimentally validate the numerical results, we developed and used a unique two dimensional wind tunnel placed above a soil tank equipped with a network of different sensors. A series of experiments under varying boundary conditions were performed. Precision data under well-controlled transient heat and wind boundary conditions was generated. Results from numerical simulations were compared with experimental data. Results demonstrate that the coupling concept can predict the different stages of the drying process in porous media with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time at low velocity values; then, at high values of wind speed the evaporation rate becomes less dependent of flow in free fluid. In the opposite, the impact of the wind speed on the second stage evaporation (diffusion dominant stage) is not significant. The proposed theoretical model can be used to predict the evaporation process where a porous medium flow is coupled to a free flow for different practical applications.

Evaluation of snowmelt simulation in the Weather Research and Forecasting model

NASA Astrophysics Data System (ADS)

Jin, Jiming; Wen, Lijuan

2012-05-01

The objective of this study is to better understand and improve snowmelt simulations in the advanced Weather Research and Forecasting (WRF) model by coupling it with the Community Land Model (CLM) Version 3.5. Both WRF and CLM are developed by the National Center for Atmospheric Research. The automated Snow Telemetry (SNOTEL) station data over the Columbia River Basin in the northwestern United States are used to evaluate snowmelt simulations generated with the coupled WRF-CLM model. These SNOTEL data include snow water equivalent (SWE), precipitation, and temperature. The simulations cover the period of March through June 2002 and focus mostly on the snowmelt season. Initial results show that when compared to observations, WRF-CLM significantly improves the simulations of SWE, which is underestimated when the release version of WRF is coupled with the Noah and Rapid Update Cycle (RUC) land surface schemes, in which snow physics is oversimplified. Further analysis shows that more realistic snow surface energy allocation in CLM is an important process that results in improved snowmelt simulations when compared to that in Noah and RUC. Additional simulations with WRF-CLM at different horizontal spatial resolutions indicate that accurate description of topography is also vital to SWE simulations. WRF-CLM at 10 km resolution produces the most realistic SWE simulations when compared to those produced with coarser spatial resolutions in which SWE is remarkably underestimated. The coupled WRF-CLM provides an important tool for research and forecasts in weather, climate, and water resources at regional scales.

Feasibility study of a swept frequency electromagnetic probe (SWEEP) using inductive coupling for the determination of subsurface conductivity of the earth and water prospecting in arid regions

NASA Technical Reports Server (NTRS)

Latorraca, G. A.; Bannister, L. H.

1974-01-01

Techniques developed for electromagnetic probing of the lunar interior, and techniques developed for the generation of high power audio frequencies were combined to make practical a magnetic inductive coupling system for the rapid measurement of ground conductivity profiles which are helpful when prospecting for the presence and quality of subsurface water. A system which involves the measurement of the direction, intensity, and time phase of the magnetic field observed near the surface of the earth at a distance from a horizontal coil energized so as to create a field that penetrates the earth was designed and studied to deduce the conductivity and stratification of the subsurface. Theoretical studies and a rudimentary experiment in an arid region showed that the approach is conceptually valid and that this geophysical prospecting technique can be developed for the economical exploration of subterranean water resources.

Urbanization accelerates long-term salinization and alkalinization of fresh water

NASA Astrophysics Data System (ADS)

Kaushal, S.; Duan, S.; Doody, T.; Haq, S.; Smith, R. M.; Newcomer Johnson, T. A.; Delaney Newcomb, K.; Gorman, J. K.; Bowman, N.; Mayer, P. M.; Wood, K. L.; Belt, K.; Stack, W.

2017-12-01

Human dominated land-use increases transport a major ions in streams due to anthropogenic salts and accelerated weathering. We show long-term trends in calcium, magnesium, sodium, alkalinity, and hardness over 50 years in the Baltimore metropolitan region and elsewhere. We also examine how major ion concentrations have increased significantly with impervious surface cover in watersheds across land use. Base cations show strong relationships with acid anions, which illustrates the coupling of major biogeochemical cycles in urban watersheds over time. Longitudinal patterns in major ions can also show increasing trends from headwaters to coastal waters, which suggests coupled biogeochemical cycles over space. We present new results from manipulative experiments and long-term monitoring across different urban regions regarding patterns and processes of salinization and alkalinization. Overall, our work demonstrates that urbanization dramatically increases major ions, ionic strength, and pH over decades from headwaters to coastal waters, which impacts the integrity of aquatic life, infrastructure, drinking water, and coastal ocean alkalinization.

Explicit modeling of groundwater-surface water interactions using a simple bucket-type model

NASA Astrophysics Data System (ADS)

Staudinger, Maria; Carlier, Claire; Brunner, Philip; Seibert, Jan

2017-04-01

Longer dry spells can become critical for water supply and groundwater dependent ecosystems. During these dry spells groundwater is often the most relevant source for streams. Hence, the hydrological behavior of a catchment is often dominated by groundwater surface water interactions, which can vary considerably in space and time. While classical hydrological approaches hardly consider this spatial dependence, quantitative, hydrogeological modeling approaches can couple surface runoff processes and groundwater processes. Hydrogeological modeling can help to gain an improved understanding of catchment processes during low flow. However, due to their complex parametrization and large computational requirements, such hydrogeological models are difficult to employ at catchment scale, particularly for a larger set of catchments. Then bucket-type hydrological models remain a practical alternative. In this study we combine the strengths of both the hydrogeological and bucket-type hydrological models to better understand low flow processes and ultimately to use this knowledge for low flow projections. Bucket-type hydrological models have traditionally not been developed with focus on the simulation of low flow. One consequence is that interactions between surface and groundwater are not explicitly considered. Water fluxes in bucket-type hydrological models are commonly simulated only in one direction, namely from the groundwater to the stream but not from the stream to the groundwater. This latter flux, however, can become more important during low flow situations. We therefore further developed the bucket-type hydrological model HBV to simulate low flow situations by allowing for exchange in both directions i.e. also from the stream to the groundwater. The additional HBV exchange box is developed by using a variety of synthetic hydrogeological models as training set that were generated using a fully coupled, physically based hydrogeological model. In this way processes that occur in different spatial settings within the catchment are translated to functional relationships and effective parameter values for the conceptual exchange box can be extracted. Here, we show the development and evaluation of the HBV exchange box. We further show a first application in real catchments and evaluate the model performance by comparing the simulations to benchmark models that do not consider groundwater surface water interaction.

Ecogeomorphology of semiarid rangelands: understanding and quantifying rates and feedbacks to prevent landscape degradation.

NASA Astrophysics Data System (ADS)

Saco, Patricia; Azadi, Samira; Moreno-de las Heras, Mariano; Keesstra, Saskia

2017-04-01

In semiarid systems, hydrologic, geomorphic and ecological processes are tightly coupled through strong feedback mechanisms occurring across fine to coarse scales. These feedbacks have implications for equilibrium and resilience of the landscape and are particularly relevant for understanding the potential degradation effects of climate and anthropogenic pressures. The vegetation of these regions is sparse and often associated to the development and maintenance of spatially variable infiltration rates, with lower infiltration in the bare areas. These variable infiltration rates have been observed in many field studies and are responsible for the emergence of a runoff-runon system, and for the associated redistribution of water and sediments. We will present a modelling framework developed to understand the role of surface water connectivity in degradation processes in semiarid landscapes with patchy vegetation. Surface water connectivity in these systems is highly dynamic and emerges from non-linear feedbacks between vegetation patterns and the coevolving landforms. The model captures these feedbacks through the coupled nature of the processes included in the landform-vegetation modules. As increased surface runoff connectivity has been linked to degradation, we focus on evolving hydrologic connectivity patterns resulting from feedback effects and co-evolving structures. First, we will discuss some general results on the coevolution of semiarid rangelands, and the effects of varying abiotic and biotic conditions. Next we will present results in which we investigate changes in functional hydrologic connectivity, and the existence of tipping points as observed in several sites in Australia. These results are based on data from our recent studies along a precipitation gradient in the Mulga bioregion of Australia. The analysis from satellite images reveals a major role of surface connectivity on the spatial organization of patchy vegetation, suggesting that transitions on the distribution of vegetation leading to degradation are related to sharp variations on the landscape surface connectivity. Finally we will discuss results analysing the potential effect of soils depths on the coevolution of system structures and connectivity. The relevance and implications of these results for the successful reclamation of water-limited environments in which vegetation stability largely depends on the redistribution of the scarce water resources will be discussed.

Assessing metaldehyde concentrations in surface water catchments and implications for drinking water abstraction

NASA Astrophysics Data System (ADS)

Asfaw, Alemayehu; Shucksmith, James; Smith, Andrea; Cherry, Katherine

2015-04-01

Metaldehyde is an active ingredient in agricultural pesticides such as slug pellets, which are heavily applied to UK farmland during the autumn application season. There is current concern that existing drinking water treatment processes may be inadequate in reducing potentially high levels of metaldehyde in surface waters to below the UK drinking water quality regulation limit of 0.1 µg/l. In addition, current water quality monitoring methods can miss short term fluctuations in metaldehyde concentration caused by rainfall driven runoff, hampering prediction of the potential risk of exposure. Datasets describing levels, fate and transport of metaldehyde in river catchments are currently very scarce. This work presents results from an ongoing study to quantify the presence of metaldehyde in surface waters within a UK catchment used for drinking water abstraction. High resolution water quality data from auto-samplers installed in rivers are coupled with radar rainfall, catchment characteristics and land use data to i) understand which hydro-meteorological characteristics of the catchment trigger the peak migration of metaldehyde to surface waters; ii) assess the relationship between measured metaldehyde levels and catchment characteristics such as land use, topographic index, proximity to water bodies and runoff generation area; iii) describe the current risks to drinking water supply and discuss mitigation options based on modelling and real-time control of water abstraction. Identifying the correlation between catchment attributes and metaldehyde generation will help in the development of effective catchment management strategies, which can help to significantly reduce the amount of metaldehyde finding its way into river water. Furthermore, the effectiveness of current water quality monitoring strategy in accurately quantifying the generation of metaldehyde from the catchment and its ability to benefit the development of effective catchment management practices has also been investigated.

Development, Testing, and Application of a Coupled Hydrodynamic Surface-Water/Groundwater Model (FTLOADDS) with Heat and Salinity Transport in the Ten Thousand Islands/Picayune Strand Restoration Project Area, Florida

USGS Publications Warehouse

Swain, Eric D.; Decker, Jeremy D.

2009-01-01

A numerical model application was developed for the coastal area inland of the Ten Thousand Islands (TTI) in southwestern Florida using the Flow and Transport in a Linked Overland/Aquifer Density-Dependent System (FTLOADDS) model. This model couples a two-dimensional dynamic surface-water model with a three-dimensional groundwater model, and has been applied to several locations in southern Florida. The model application solves equations for salt transport in groundwater and surface water, and also simulates surface-water temperature using a newly enhanced heat transport algorithm. One of the purposes of the TTI application is to simulate hydrologic factors that relate to habitat suitability for the West Indian Manatee. Both salinity and temperature have been shown to be important factors for manatee survival. The inland area of the TTI domain is the location of the Picayune Strand Restoration Project, which is designed to restore predevelopment hydrology through the filling and plugging of canals, construction of spreader channels, and the construction of levees and pump stations. The effects of these changes are simulated to determine their effects on manatee habitat. The TTI application utilizes a large amount of input data for both surface-water and groundwater flow simulations. These data include topography, frictional resistance, atmospheric data including rainfall and air temperature, aquifer properties, and boundary conditions for tidal levels, inflows, groundwater heads, and salinities. Calibration was achieved by adjusting the parameters having the largest uncertainty: surface-water inflows, the surface-water transport dispersion coefficient, and evapotranspiration. A sensitivity analysis did not indicate that further parameter changes would yield an overall improvement in simulation results. The agreement between field data from GPS-tracked manatees and TTI application results demonstrates that the model can predict the salinity and temperature fluctuations which affect manatee behavior. Comparison of the existing conditions simulation with the simulation incorporating restoration changes indicated that the restoration would increase the period of inundation for most of the coastal wetlands. Generally, surface-water salinity was lowered by restoration changes in most of the wetlands areas, especially during the early dry season. However, the opposite pattern was observed in the primary canal habitat for manatees, namely, the Port of the Islands. Salinities at this location tended to be moderately elevated during the dry season, and unchanged during the wet season. Water temperatures were in close agreement between the existing conditions and restoration simulations, although minimum temperatures at the Port of the Islands were slightly higher in the restoration simulation as a result of the additional surface-water ponding and warming that occurs in adjacent wetlands. The TTI application output was used to generate salinity and temperature time series for comparison to manatee field tracking data and an individually-based manatee-behavior model. Overlaying field data with salinity and temperature results from the TTI application reflects the effect of warm water availability and the periodic need for low-salinity drinking water on manatee movements. The manatee-behavior model uses the TTI application data at specific model nodes along the main manatee travel corridors to determine manatee migration patterns. The differences between the existing conditions and restoration scenarios can then be compared for manatee refugia. The TTI application can be used to test a variety of hydrologic conditions and their effect on important criteria.

International borders, ground water flow, and hydroschizophrenia.

PubMed

Jarvis, Todd; Giordano, Mark; Puri, Shammy; Matsumoto, Kyoko; Wolf, Aaron

2005-01-01

A substantial body of research has been conducted on transboundary water, transboundary water law, and the mitigation of transboundary water conflict. However, most of this work has focused primarily on surface water supplies. While it is well understood that aquifers cross international boundaries and that the base flow of international river systems is often derived in part from ground water, transboundary ground water and surface water systems are usually managed under different regimes, resulting in what has been described as "hydroschizophrenia." Adding to the problem, the hydrologic relationships between surface and ground water supplies are only known at a reconnaissance level in even the most studied international basins, and thus even basic questions regarding the territorial sovereignty of ground water resources often remain unaddressed or even unasked. Despite the tensions inherent in the international setting, riparian nations have shown tremendous creativity in approaching regional development, often through preventive diplomacy, and the creation of "baskets of benefits," which allow for positive-sum, integrative allocations of joint gains. In contrast to the notion of imminent water wars, the history of hydropolitical relations worldwide has been overwhelmingly cooperative. Limited ground water management in the international arena, coupled with the fact that few states or countries regulate the use of ground water, begs the question: will international borders serve as boundaries for increased "flows" of hydrologic information and communication to maintain strategic aquifers, or will increased competition for shared ground water resources lead to the potential loss of strategic aquifers and "no flows" for both ground water users?

Exchange of groundwater and surface-water mediated by permafrost response to seasonal and long term air temperature variation

USGS Publications Warehouse

Ge, S.; McKenzie, J.; Voss, C.; Wu, Q.

2011-01-01

Permafrost dynamics impact hydrologic cycle processes by promoting or impeding groundwater and surface water exchange. Under seasonal and decadal air temperature variations, permafrost temperature changes control the exchanges between groundwater and surface water. A coupled heat transport and groundwater flow model, SUTRA, was modified to simulate groundwater flow and heat transport in the subsurface containing permafrost. The northern central Tibet Plateau was used as an example of model application. Modeling results show that in a yearly cycle, groundwater flow occurs in the active layer from May to October. Maximum groundwater discharge to the surface lags the maximum subsurface temperature by two months. Under an increasing air temperature scenario of 3C per 100 years, over the initial 40-year period, the active layer thickness can increase by three-fold. Annual groundwater discharge to the surface can experience a similar three-fold increase in the same period. An implication of these modeling results is that with increased warming there will be more groundwater flow in the active layer and therefore increased groundwater discharge to rivers. However, this finding only holds if sufficient upgradient water is available to replenish the increased discharge. Otherwise, there will be an overall lowering of the water table in the recharge portion of the catchment. Copyright 2011 by the American Geophysical Union.

Detailed study of the water trimer potential energy surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, J.E.; Schaefer, H.F. III

The potential energy surface of the water trimer has been studied through the use of ab initio quantum mechanical methods. Five stationary points were located, including one minimum and two transition states. All geometries were optimized at levels up to the double-[Zeta] plus polarization plus diffuse (DZP + diff) single and double excitation coupled cluster (CCSD) level of theory. CCSD single energy points were obtained for the minimum, two transition states, and the water monomer using the triple-[Zeta] plus double polarization plus diffuse (TZ2P + diff) basis at the geometries predicted by the DZP + diff CCSD method. Reported aremore » the following: geometrical parameters, total and relative energies, harmonic vibrational frequencies and infrared intensities for the minimum, and zero point vibrational energies for the minimum, two transition states, and three separated water molecules. 27 refs., 5 figs., 10 tabs.« less

Water Dimers in the Atmosphere II: Results from the VRT(ASP-W)III Potential Surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldman, N; Saykally, R J; Leforestier, C

We report refined results for the equilibrium constant for water dimerization (K{sub P}), computed as a function of temperature via fully-coupled 6-D calculation of the canonical (H{sub 2}O){sub 2} partition function on VRT(ASP-W)III, the most accurate water dimer potential energy surface currently available. Partial pressure isotherms calculated for a range of temperatures and relative humidities indicate that water dimers can exist in sufficient concentrations (e.g., 10{sup 18}m{sup -3} at 30 C and 100% relative humidity) to affect physical and chemical processes in the atmosphere. The determinations of additional thermodynamic properties ({Delta}G, {Delta}H, {Delta}S, C{sub P}, C{sub V}) for (H{sub 2}O){submore » 2} are presented, and the role of quasi-bound states in the calculation of K{sub P} is discussed at length.« less

Measurement of the adsorption energy difference between ortho- and para-D2 on an amorphous ice surface.

PubMed

Amiaud, L; Momeni, A; Dulieu, F; Fillion, J H; Matar, E; Lemaire, J-L

2008-02-08

Molecular hydrogen interaction on water ice surfaces is a major process taking place in interstellar dense clouds. By coupling laser detection and classical thermal desorption spectroscopy, it is possible to study the effect of rotation of D(2) on adsorption on amorphous solid water ice surfaces. The desorption profiles of ortho- and para-D(2) are different. This difference is due to a shift in the adsorption energy distribution of the two lowest rotational states. Molecules in J''=1 rotational state are on average more strongly bound to the ice surface than those in J''=0 rotational state. This energy difference is estimated to be 1.4+/-0.3 meV. This value is in agreement with previous calculation and interpretation. The nonspherical wave function J'' =1 has an interaction with the asymmetric part of the adsorption potential and contributes positively in the binding energy.

Urban runoff (URO) process for MODFLOW 2005: simulation of sub-grid scale urban hydrologic processes in Broward County, FL

USGS Publications Warehouse

Decker, Jeremy D.; Hughes, J.D.

2013-01-01

Climate change and sea-level rise could cause substantial changes in urban runoff and flooding in low-lying coast landscapes. A major challenge for local government officials and decision makers is to translate the potential global effects of climate change into actionable and cost-effective adaptation and mitigation strategies at county and municipal scales. A MODFLOW process is used to represent sub-grid scale hydrology in urban settings to help address these issues. Coupled interception, surface water, depression, and unsaturated zone storage are represented. A two-dimensional diffusive wave approximation is used to represent overland flow. Three different options for representing infiltration and recharge are presented. Additional features include structure, barrier, and culvert flow between adjacent cells, specified stage boundaries, critical flow boundaries, source/sink surface-water terms, and the bi-directional runoff to MODFLOW Surface-Water Routing process. Some abilities of the Urban RunOff (URO) process are demonstrated with a synthetic problem using four land uses and varying cell coverages. Precipitation from a hypothetical storm was applied and cell by cell surface-water depth, groundwater level, infiltration rate, and groundwater recharge rate are shown. Results indicate the URO process has the ability to produce time-varying, water-content dependent infiltration and leakage, and successfully interacts with MODFLOW.

The Soil-Plant-Atmosphere System - Past and Present.

NASA Astrophysics Data System (ADS)

Berry, J. A.; Baker, I. T.; Randall, D. A.; Sellers, P. J.

2012-12-01

Plants with stomata, roots and a vascular system first appeared on earth about 415 million years ago. This evolutionary innovation helped to set in motion non-linear feedback mechanisms that led to an acceleration of the hydrologic cycle over the continents and an expansion of the climate zones favorable for plant (and animal) life. Skeletal soils that developed long before plants came onto the land would have held water and nutrients in their pore space, yet these resources would have been largely unavailable to primitive, surface-dwelling non-vascular plants due to physical limitations on water transport once the surface layer of soil dries. Plants with roots and a vascular system that could span this dry surface layer could gain increased and prolonged access to the water and nutrients stored in the soil for photosynthesis. Maintenance of the hydraulic connections permitting water to be drawn through the vascular system from deep in the soil to the sites of evaporation in the leaves required a cuticle and physiological regulation of stomata. These anatomical and physiological innovations changed properties of the terrestrial surface (albedo, roughness, a vascular system and control of surface conductance) and set in motion complex interactions of the soil - plant - atmosphere system. We will use coupled physiological and meteorological models to examine some of these interactions.

Fabrication of TiO2/EP super-hydrophobic thin film on filter paper surface.

PubMed

Gao, Zhengxin; Zhai, Xianglin; Liu, Feng; Zhang, Ming; Zang, Deli; Wang, Chengyu

2015-09-05

A composite filter paper with super-hydrophobicity was obtained by adhering micro/nano structure of amorphous titanium dioxide on the filter paper surface with modifying low surface energy material. By virtue of the coupling agent, which plays an important part in bonding amorphous titanium dioxide and epoxy resin, the structure of super-hydrophobic thin film on the filter paper surface is extremely stable. The microstructure of super-hydrophobic filter paper was characterized by scanning electron microscopy (SEM), the images showed that the as-prepared filter paper was covered with uniform amorphous titanium dioxide particles, generating a roughness structure on the filter paper surface. The super-hydrophobic performance of the filter paper was characterized by water contact angle measurements. The observations showed that the wettability of filter paper samples transformed from super-hydrophilicity to super-hydrophobicity with the water contact angle of 153 ± 1°. Some experiments were also designed to test the effect of water-oil separation and UV-resistant by the super-hydrophobic filter paper. The prepared super-hydrophobic filter paper worked efficiently and simply in water-oil separation as well as enduringly in anti-UV property after the experiments. This method offers an opportunity to the practical applications of the super-hydrophobic filter paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coupling between the Dynamics of Water and Surfactants in Lyotropic Liquid Crystals

DOE PAGES

McDaniel, Jesse G.; Yethiraj, Arun

2017-04-26

Bilayers composed of lipid or surfactant molecules are central to biological membranes and lamellar lyotropic liquid crystalline (LLC) phases. Common to these systems are phases that exhibit either ordered or disordered packing of the hydrophobic tails. In this work, we study the impact of surfactant ordering, i.e., disordered L α and ordered L β LLC phases, on the dynamics of water and sodium ions in the lamellar phases of dicarboxylate gemini surfactants. We study the different phases at identical hydration levels by changing the length of the hydrophobic tails; surfactants with shorter tails form L α phases and those withmore » longer tails form L β phases. We find that the L α phases exhibit lower density and greater compressibility than the L β phases, with a hydration-dependent headgroup surface area. These structural differences significantly affect the relative dynamic properties of the phases, primarily the mobility of the surfactant molecules tangential to the bilayer surface, as well as the rates of water and ion diffusion. We find ~20–50% faster water diffusion in the L α phases compared to the L β phases, with the differences most pronounced at low hydration. This coupling between water dynamics and surfactant mobility is verified using additional simulations in which the surfactant tails are frozen. Our study indicates that gemini surfactant LLCs provide an important prototypical system for characterizing properties shared with more complex biological lipid membranes.« less

An Analytic Approach to Modeling Land-Atmosphere Interaction: 1. Construct and Equilibrium Behavior

NASA Astrophysics Data System (ADS)

Brubaker, Kaye L.; Entekhabi, Dara

1995-03-01

A four-variable land-atmosphere model is developed to investigate the coupled exchanges of water and energy between the land surface and atmosphere and the role of these exchanges in the statistical behavior of continental climates. The land-atmosphere system is substantially simplified and formulated as a set of ordinary differential equations that, with the addition of random noise, are suitable for analysis in the form of the multivariate Îto equation. The model treats the soil layer and the near-surface atmosphere as reservoirs with storage capacities for heat and water. The transfers between these reservoirs are regulated by four states: soil saturation, soil temperature, air specific humidity, and air potential temperature. The atmospheric reservoir is treated as a turbulently mixed boundary layer of fixed depth. Heat and moisture advection, precipitation, and layer-top air entrainment are parameterized. The system is forced externally by solar radiation and the lateral advection of air and water mass. The remaining energy and water mass exchanges are expressed in terms of the state variables. The model development and equilibrium solutions are presented. Although comparisons between observed data and steady state model results re inexact, the model appears to do a reasonable job of partitioning net radiation into sensible and latent heat flux in appropriate proportions for bare-soil midlatitude summer conditions. Subsequent work will introduce randomness into the forcing terms to investigate the effect of water-energy coupling and land-atmosphere interaction on variability and persistence in the climatic system.

Groundwater modeling in integrated water resources management--visions for 2020.

PubMed

Refsgaard, Jens Christian; Højberg, Anker Lajer; Møller, Ingelise; Hansen, Martin; Søndergaard, Verner

2010-01-01

Groundwater modeling is undergoing a change from traditional stand-alone studies toward being an integrated part of holistic water resources management procedures. This is illustrated by the development in Denmark, where comprehensive national databases for geologic borehole data, groundwater-related geophysical data, geologic models, as well as a national groundwater-surface water model have been established and integrated to support water management. This has enhanced the benefits of using groundwater models. Based on insight gained from this Danish experience, a scientifically realistic scenario for the use of groundwater modeling in 2020 has been developed, in which groundwater models will be a part of sophisticated databases and modeling systems. The databases and numerical models will be seamlessly integrated, and the tasks of monitoring and modeling will be merged. Numerical models for atmospheric, surface water, and groundwater processes will be coupled in one integrated modeling system that can operate at a wide range of spatial scales. Furthermore, the management systems will be constructed with a focus on building credibility of model and data use among all stakeholders and on facilitating a learning process whereby data and models, as well as stakeholders' understanding of the system, are updated to currently available information. The key scientific challenges for achieving this are (1) developing new methodologies for integration of statistical and qualitative uncertainty; (2) mapping geological heterogeneity and developing scaling methodologies; (3) developing coupled model codes; and (4) developing integrated information systems, including quality assurance and uncertainty information that facilitate active stakeholder involvement and learning.

Pilot monitoring study of ibuprofen in surface waters of north of Portugal.

PubMed

Paíga, Paula; Santos, Lúcia H M L M; Amorim, Célia G; Araújo, Alberto N; Montenegro, M Conceição B S M; Pena, Angelina; Delerue-Matos, Cristina

2013-04-01

Ibuprofen is amongst the most worldwide consumed pharmaceuticals. The present work presents the first data in the occurrence of ibuprofen in Portuguese surface waters, focusing in the north area of the country, which is one of the most densely populated areas of Portugal. Analysis of ibuprofen is based on pre-concentration of the analyte with solid phase extraction and subsequent determination with liquid chromatography coupled to fluorescence detection. A total of 42 water samples, including surface waters, landfill leachates, Wastewater Treatment Plant (WWTP), and hospital effluents, were analyzed in order to evaluate the occurrence of ibuprofen in the north of Portugal. In general, the highest concentrations were found in the river mouths and in the estuarine zone. The maximum concentrations found were 48,720 ng L(-1) in the landfill leachate, 3,868 ng L(-1) in hospital effluent, 616 ng L(-1) in WWTP effluent, and 723 ng L(-1) in surface waters (Lima river). Environmental risk assessment was evaluated and at the measured concentrations only landfill leachates reveal potential ecotoxicological risk for aquatic organisms. Owing to a high consumption rate of ibuprofen among Portuguese population, as prescribed and non-prescribed medicine, the importance of hospitals, WWTPs, and landfills as sources of entrance of pharmaceuticals in the environment was pointed out. Landfill leachates showed the highest contribution for ibuprofen mass loading into surface waters. On the basis of our findings, more studies are needed as an attempt to assess more vulnerable areas.

Methylene migration and coupling on a non-reducible metal oxide: The reaction of dichloromethane on stoichiometric α-Cr 2O 3(0001)

DOE PAGES

Dong, Yujung; Brooks, John D.; Chen, Tsung-Liang; ...

2014-09-17

The reaction of CH 2Cl 2 over the nearly-stoichiometric α-Cr 2O 3(0001) surface produces gas phase ethylene, methane and surface chlorine adatoms. The reaction is initiated by the decomposition of CH 2Cl 2 into surface methylene and chlorine. Photoemission indicates that surface cations are the preferred binding sites for both methylene and chlorine adatoms. Two reaction channels are observed for methylene coupling to ethylene in temperature-programmed desorption (TPD). A desorption-limited, low-temperature route is attributed to two methylenes bound at a single site. The majority of ethylene is produced by a reaction-limited process involving surface migration (diffusion) of methylene as themore » rate-limiting step. DFT calculations indicate the surface diffusion mechanism is mediated by surface oxygen anions. The source of hydrogen for methane formation is adsorbed background water. Chlorine adatoms produced by the dissociation of CH 2Cl 2 deactivate the surface by simple site-blocking of surface Cr 3+ sites. Finally, a comparison of experiment and theory shows that DFT provides a better description of the surface chemistry of the carbene intermediate than DFT+U using reported parameters for a best representation of the bulk electronic properties of α-Cr 2O 3.« less

Enhanced nitrogen loss from rivers through coupled nitrification-denitrification caused by suspended sediment.

PubMed

Xia, Xinghui; Liu, Ting; Yang, Zhifeng; Michalski, Greg; Liu, Shaoda; Jia, Zhimei; Zhang, Sibo

2017-02-01

Present-day estimations of global nitrogen loss (N-loss) are underestimated. Commonly, N-loss from rivers is thought to be caused by denitrification only in bed-sediments. However, coupled nitrification-denitrification occurring in overlying water with suspended sediments (SPS) where oxic and anoxic/low oxygen zones may coexist is ignored for N-loss in rivers. Here the Yellow and Yangtze Rivers were taken as examples to investigate the effect of SPS, which exists in many rivers of the world, on N loss through coupled nitrification-denitrification with nitrogen stable ( 15 N) isotopic tracer simulation experiments and in-situ investigation. The results showed even when SPS was surrounded by oxic waters, there were redox conditions that transitioned from an oxic surface layer to anoxic layer near the particle center, enabling coupled nitrification-denitrification to occur around SPS. The production rate of 15 N 2 from 15 NH 4 + -N (R 15N2-production ) increased with increasing SPS concentration ([SPS]) as a power function (R 15N2-production =a·[SPS] b ) for both the SPS-water and bed sediment-SPS-water systems. The power-functional increase of nitrifying and denitrifying bacteria population with [SPS] accounted for the enhanced coupled nitrification-denitrification rate in overlying water. SPS also accelerated denitrification in bed-sediment due to increased NO 3 - concentration caused by SPS-mediated nitrification. For these two rivers, 1gL -1 SPS will lead to N-loss enhancement by approximately 25-120%, and the enhancement increased with organic carbon content of SPS. Thus, we conclude that SPS in overlying water is a hot spot for nitrogen loss in river systems and current estimates of in-stream N-loss are underestimated without consideration of SPS; this may partially compensate for the current imbalance of global nitrogen inputs and sinks. Copyright © 2016 Elsevier B.V. All rights reserved.

Effective use of integrated hydrological models in basin-scale water resources management: surrogate modeling approaches

NASA Astrophysics Data System (ADS)

Zheng, Y.; Wu, B.; Wu, X.

2015-12-01

Integrated hydrological models (IHMs) consider surface water and subsurface water as a unified system, and have been widely adopted in basin-scale water resources studies. However, due to IHMs' mathematical complexity and high computational cost, it is difficult to implement them in an iterative model evaluation process (e.g., Monte Carlo Simulation, simulation-optimization analysis, etc.), which diminishes their applicability for supporting decision-making in real-world situations. Our studies investigated how to effectively use complex IHMs to address real-world water issues via surrogate modeling. Three surrogate modeling approaches were considered, including 1) DYCORS (DYnamic COordinate search using Response Surface models), a well-established response surface-based optimization algorithm; 2) SOIM (Surrogate-based Optimization for Integrated surface water-groundwater Modeling), a response surface-based optimization algorithm that we developed specifically for IHMs; and 3) Probabilistic Collocation Method (PCM), a stochastic response surface approach. Our investigation was based on a modeling case study in the Heihe River Basin (HRB), China's second largest endorheic river basin. The GSFLOW (Coupled Ground-Water and Surface-Water Flow Model) model was employed. Two decision problems were discussed. One is to optimize, both in time and in space, the conjunctive use of surface water and groundwater for agricultural irrigation in the middle HRB region; and the other is to cost-effectively collect hydrological data based on a data-worth evaluation. Overall, our study results highlight the value of incorporating an IHM in making decisions of water resources management and hydrological data collection. An IHM like GSFLOW can provide great flexibility to formulating proper objective functions and constraints for various optimization problems. On the other hand, it has been demonstrated that surrogate modeling approaches can pave the path for such incorporation in real-world situations, since they can dramatically reduce the computational cost of using IHMs in an iterative model evaluation process. In addition, our studies generated insights into the human-nature water conflicts in the specific study area and suggested potential solutions to address them.

On the role of surface friction in tropical cyclone intensification

NASA Astrophysics Data System (ADS)

Wang, Yuqing

2017-04-01

Recent studies have debated on whether surface friction is positive or negative to tropical cyclone intensification in the view on angular momentum budget. That means whether the frictionally induced inward angular momentum transport can overcome the loss of angular momentum to the surface due to surface friction itself. Although this issue is still under debate, this study investigates another implicit dynamical effect, which modifies the radial location and strength of eyewall convection. We found that moderate surface friction is necessary for rapid intensity of tropical cyclones. This is demonstrated first by a simple coupled dynamical system that couples a multi-level boundary layer model and a shallow water equation model above with mass source parameterized by mass flux from the boundary layer model below, and then by a full physics model. The results show that surface friction leads to the inward penetration of inflow under the eyewall, shift the boundary layer mass convergence slightly inside the radius of maximum wind, and enhance the upward mass flux, and thus diabatic heating in the eyewall and intensification rate of a TC. This intensification process is different from the direct angular momentum budget previously used to explain the role of surface friction in tropical cyclone intensification.

Coupling biophysical processes and water rights to simulate spatially distributed water use in an intensively managed hydrologic system

NASA Astrophysics Data System (ADS)

Han, Bangshuai; Benner, Shawn G.; Bolte, John P.; Vache, Kellie B.; Flores, Alejandro N.

2017-07-01

Humans have significantly altered the redistribution of water in intensively managed hydrologic systems, shifting the spatiotemporal patterns of surface water. Evaluating water availability requires integration of hydrologic processes and associated human influences. In this study, we summarize the development and evaluation of an extensible hydrologic model that explicitly integrates water rights to spatially distribute irrigation waters in a semi-arid agricultural region in the western US, using the Envision integrated modeling platform. The model captures both human and biophysical systems, particularly the diversion of water from the Boise River, which is the main water source that supports irrigated agriculture in this region. In agricultural areas, water demand is estimated as a function of crop type and local environmental conditions. Surface water to meet crop demand is diverted from the stream reaches, constrained by the amount of water available in the stream, the water-rights-appropriated amount, and the priority dates associated with particular places of use. Results, measured by flow rates at gaged stream and canal locations within the study area, suggest that the impacts of irrigation activities on the magnitude and timing of flows through this intensively managed system are well captured. The multi-year averaged diverted water from the Boise River matches observations well, reflecting the appropriation of water according to the water rights database. Because of the spatially explicit implementation of surface water diversion, the model can help diagnose places and times where water resources are likely insufficient to meet agricultural water demands, and inform future water management decisions.

End Functionalized Nonionic Water-Dispersible Conjugated Polymers.

PubMed

Zhan, Ruoyu; Liu, Bin

2017-09-01

2,7-Dibromofluorene monomers carrying two or four oligo(ethylene glycol) (OEG) side chains are synthesized. Heck coupling between the monomers and 1,4-divinylbenzene followed by end capping with [4-(4-bromophenoxy)butyl]carbamic acid tert-butyl ester leads to two nonionic water-dispersible poly(fluorene-alt-1,4-divinylenephenylene)s end-functionalized with amine groups after hydrolysis. In water, the polymer with a lower OEG density (P1) has poor water dispersibility with a quantum yield of 0.24, while the polymer with a higher OEG density (P2) possesses excellent water-dispersibility with a high quantum yield of 0.45. Both polymers show fluorescence enhancement and blue-shifted absorption and emission maxima in the presence of surfactant sodium dodecyl sulfate and dodecyltrimethylammonium bromide. The polymers are also resistant to ionic strength with minimal nonspecific interactions to bovine serum albumin. When biotin is incorporated into the end of the polymer backbones through N-hydroxysuccinimide/amine coupling reaction, the biotinylated polymers interact specifically with streptavidin on solid surface. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radio Frequency Detection and Characterization of Water-Ethanol Solution through Spiral-Coupled Passive Micro-Resonator Sensor.

PubMed

Koirala, Gyan Raj; Dhakal, Rajendra; Kim, Eun-Seong; Yao, Zhao; Kim, Nam-Young

2018-04-03

We present a microfabricated spiral-coupled passive resonator sensor realized through integrated passive device (IPD) technology for the sensitive detection and characterization of water-ethanol solutions. In order to validate the performance of the proposed device, we explicitly measured and analyzed the radio frequency (RF) characteristics of various water-ethanol solution compositions. The measured results showed a drift in the resonance frequency from 1.16 GHz for deionized (DI) water to 1.68 GHz for the solution containing 50% ethanol, whereas the rejection level given by the reflection coefficient decreased from -29.74 dB to -14.81 dB. The obtained limit of detection was 3.82% volume composition of ethanol in solution. The derived loaded capacitance was 21.76 pF for DI water, which gradually decreased to 8.70 pF for the 50% ethanol solution, and the corresponding relative permittivity of the solution decreased from 80.14 to 47.79. The dissipation factor increased with the concentration of ethanol in the solution. We demonstrated the reproducibility of the proposed sensor through iterative measures of the samples and the study of surface morphology. Successive measurement of different samples had no overlapping and had very minimum bias between RF characteristics for each measured sample. The surface profile for bare sensors was retained after the sample test, resulting a root mean square (RMS) value of 11.416 nm as compared to 10.902 nm for the bare test. The proposed sensor was shown to be a viable alternative to existing sensors for highly sensitive water-ethanol concentration detection.

Imaging spectrometer measurement of water vapor in the 400 to 2500 nm spectral region

NASA Technical Reports Server (NTRS)

Green, Robert O.; Roberts, Dar A.; Conel, James E.; Dozier, Jeff

1995-01-01

The Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) measures the total upwelling spectral radiance from 400 to 2500 nm sampled at 10 nm intervals. The instrument acquires spectral data at an altitude of 20 km above sea level, as images of 11 by up to 100 km at 17x17 meter spatial sampling. We have developed a nonlinear spectral fitting algorithm coupled with a radiative transfer code to derive the total path water vapor from the spectrum, measured for each spatial element in an AVIRIS image. The algorithm compensates for variation in the surface spectral reflectance and atmospheric aerosols. It uses water vapor absorption bands centered at 940 nm, 1040 nm, and 1380 nm. We analyze data sets with water vapor abundances ranging from 1 to 40 perceptible millimeters. In one data set, the total path water vapor varies from 7 to 21 mm over a distance of less than 10 km. We have analyzed a time series of five images acquired at 12 minute intervals; these show spatially heterogeneous changes of advocated water vapor of 25 percent over 1 hour. The algorithm determines water vapor for images with a range of ground covers, including bare rock and soil, sparse to dense vegetation, snow and ice, open water, and clouds. The precision of the water vapor determination approaches one percent. However, the precision is sensitive to the absolute abundance and the absorption strength of the atmospheric water vapor band analyzed. We have evaluated the accuracy of the algorithm by comparing several surface-based determinations of water vapor at the time of the AVIRIS data acquisition. The agreement between the AVIRIS measured water vapor and the in situ surface radiometer and surface interferometer measured water vapor is 5 to 10 percent.

Coupled Effects of Natural and Anthropogenic Controls on Seasonal and Spatial Variations of River Water Quality during Baseflow in a Coastal Watershed of Southeast China

PubMed Central

Huang, Jinliang; Huang, Yaling; Zhang, Zhenyu

2014-01-01

Surface water samples of baseflow were collected from 20 headwater sub-watersheds which were classified into three types of watersheds (natural, urban and agricultural) in the flood, dry and transition seasons during three consecutive years (2010–2012) within a coastal watershed of Southeast China. Integrating spatial statistics with multivariate statistical techniques, river water quality variations and their interactions with natural and anthropogenic controls were examined to identify the causal factors and underlying mechanisms governing spatiotemporal patterns of water quality. Anthropogenic input related to industrial effluents and domestic wastewater, agricultural activities associated with the precipitation-induced surface runoff, and natural weathering process were identified as the potential important factors to drive the seasonal variations in stream water quality for the transition, flood and dry seasons, respectively. All water quality indicators except SRP had the highest mean concentrations in the dry and transition seasons. Anthropogenic activities and watershed characteristics led to the spatial variations in stream water quality in three types of watersheds. Concentrations of NH4 +-N, SRP, K+, CODMn, and Cl− were generally highest in urban watersheds. NO3 –N Concentration was generally highest in agricultural watersheds. Mg2+ concentration in natural watersheds was significantly higher than that in agricultural watersheds. Spatial autocorrelations analysis showed similar levels of water pollution between the neighboring sub-watersheds exhibited in the dry and transition seasons while non-point source pollution contributed to the significant variations in water quality between neighboring sub-watersheds. Spatial regression analysis showed anthropogenic controls played critical roles in variations of water quality in the JRW. Management implications were further discussed for water resource management. This research demonstrates that the coupled effects of natural and anthropogenic controls involved in watershed processes, contribute to the seasonal and spatial variation of headwater stream water quality in a coastal watershed with high spatial variability and intensive anthropogenic activities. PMID:24618771

Effects of explicit convection on global land-atmosphere coupling in the superparameterized CAM

DOE PAGES

Sun, Jian; Pritchard, Michael S.

2016-07-25

Here, conventional global climate models are prone to producing unrealistic land-atmosphere coupling signals. Cumulus and convection parameterizations are natural culprits but the effect of bypassing them with explicitly resolved convection on global land-atmosphere coupling dynamics has not been explored systematically. We apply a suite of modern land-atmosphere coupling diagnostics to isolate the effect of cloud Superparameterization in the Community Atmosphere Model (SPCAM) v3.5, focusing on both the terrestrial segment (i.e., soil moisture and surface turbulent fluxes interaction) and atmospheric segment (i.e., surface turbulent fluxes and precipitation interaction) in the water pathway of the landatmosphere feedback loop. At daily timescales, SPCAMmore » produces stronger uncoupled terrestrial signals (negative sign) over tropical rainforests in wet seasons, reduces the terrestrial coupling strength in the Central Great Plain in American, and reverses the coupling sign (from negative to positive) over India in the boreal summer season—all favorable improvements relative to reanalysis-forced land modeling. Analysis of the triggering feedback strength (TFS) and amplification feedback strength (AFS) shows that SPCAM favorably reproduces the observed geographic patterns of these indices over North America, with the probability of afternoon precipitation enhanced by high evaporative fraction along the eastern United States and Mexico, while conventional CAM does not capture this signal. We introduce a new diagnostic called the Planetary Boundary Layer (PBL) Feedback Strength (PFS), which reveals that SPCAM exhibits a tight connection between the responses of the lifting condensation level, the PBL height, and the rainfall triggering to surface turbulent fluxes; a triggering disconnect is found in CAM.« less

Effects of explicit convection on global land-atmosphere coupling in the superparameterized CAM

NASA Astrophysics Data System (ADS)

Sun, Jian; Pritchard, Michael S.

2016-09-01

Conventional global climate models are prone to producing unrealistic land-atmosphere coupling signals. Cumulus and convection parameterizations are natural culprits but the effect of bypassing them with explicitly resolved convection on global land-atmosphere coupling dynamics has not been explored systematically. We apply a suite of modern land-atmosphere coupling diagnostics to isolate the effect of cloud Superparameterization in the Community Atmosphere Model (SPCAM) v3.5, focusing on both the terrestrial segment (i.e., soil moisture and surface turbulent fluxes interaction) and atmospheric segment (i.e., surface turbulent fluxes and precipitation interaction) in the water pathway of the land-atmosphere feedback loop. At daily timescales, SPCAM produces stronger uncoupled terrestrial signals (negative sign) over tropical rainforests in wet seasons, reduces the terrestrial coupling strength in the Central Great Plain in American, and reverses the coupling sign (from negative to positive) over India in the boreal summer season—all favorable improvements relative to reanalysis-forced land modeling. Analysis of the triggering feedback strength (TFS) and amplification feedback strength (AFS) shows that SPCAM favorably reproduces the observed geographic patterns of these indices over North America, with the probability of afternoon precipitation enhanced by high evaporative fraction along the eastern United States and Mexico, while conventional CAM does not capture this signal. We introduce a new diagnostic called the Planetary Boundary Layer (PBL) Feedback Strength (PFS), which reveals that SPCAM exhibits a tight connection between the responses of the lifting condensation level, the PBL height, and the rainfall triggering to surface turbulent fluxes; a triggering disconnect is found in CAM.

Effects of explicit convection on global land-atmosphere coupling in the superparameterized CAM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Jian; Pritchard, Michael S.

Here, conventional global climate models are prone to producing unrealistic land-atmosphere coupling signals. Cumulus and convection parameterizations are natural culprits but the effect of bypassing them with explicitly resolved convection on global land-atmosphere coupling dynamics has not been explored systematically. We apply a suite of modern land-atmosphere coupling diagnostics to isolate the effect of cloud Superparameterization in the Community Atmosphere Model (SPCAM) v3.5, focusing on both the terrestrial segment (i.e., soil moisture and surface turbulent fluxes interaction) and atmospheric segment (i.e., surface turbulent fluxes and precipitation interaction) in the water pathway of the landatmosphere feedback loop. At daily timescales, SPCAMmore » produces stronger uncoupled terrestrial signals (negative sign) over tropical rainforests in wet seasons, reduces the terrestrial coupling strength in the Central Great Plain in American, and reverses the coupling sign (from negative to positive) over India in the boreal summer season—all favorable improvements relative to reanalysis-forced land modeling. Analysis of the triggering feedback strength (TFS) and amplification feedback strength (AFS) shows that SPCAM favorably reproduces the observed geographic patterns of these indices over North America, with the probability of afternoon precipitation enhanced by high evaporative fraction along the eastern United States and Mexico, while conventional CAM does not capture this signal. We introduce a new diagnostic called the Planetary Boundary Layer (PBL) Feedback Strength (PFS), which reveals that SPCAM exhibits a tight connection between the responses of the lifting condensation level, the PBL height, and the rainfall triggering to surface turbulent fluxes; a triggering disconnect is found in CAM.« less

Sensitivity of open-water ice growth and ice concentration evolution in a coupled atmosphere-ocean-sea ice model

NASA Astrophysics Data System (ADS)

Shi, Xiaoxu; Lohmann, Gerrit

2017-09-01

A coupled atmosphere-ocean-sea ice model is applied to investigate to what degree the area-thickness distribution of new ice formed in open water affects the ice and ocean properties. Two sensitivity experiments are performed which modify the horizontal-to-vertical aspect ratio of open-water ice growth. The resulting changes in the Arctic sea-ice concentration strongly affect the surface albedo, the ocean heat release to the atmosphere, and the sea-ice production. The changes are further amplified through a positive feedback mechanism among the Arctic sea ice, the Atlantic Meridional Overturning Circulation (AMOC), and the surface air temperature in the Arctic, as the Fram Strait sea ice import influences the freshwater budget in the North Atlantic Ocean. Anomalies in sea-ice transport lead to changes in sea surface properties of the North Atlantic and the strength of AMOC. For the Southern Ocean, the most pronounced change is a warming along the Antarctic Circumpolar Current (ACC), owing to the interhemispheric bipolar seasaw linked to AMOC weakening. Another insight of this study lies on the improvement of our climate model. The ocean component FESOM is a newly developed ocean-sea ice model with an unstructured mesh and multi-resolution. We find that the subpolar sea-ice boundary in the Northern Hemisphere can be improved by tuning the process of open-water ice growth, which strongly influences the sea ice concentration in the marginal ice zone, the North Atlantic circulation, salinity and Arctic sea ice volume. Since the distribution of new ice on open water relies on many uncertain parameters and the knowledge of the detailed processes is currently too crude, it is a challenge to implement the processes realistically into models. Based on our sensitivity experiments, we conclude a pronounced uncertainty related to open-water sea ice growth which could significantly affect the climate system sensitivity.

Evolution of Subaerial Coastal Fluvial Delta Island Topography into Multiple Stable States Under Influence of Vegetation and Stochastic Hydrology

NASA Astrophysics Data System (ADS)

Moffett, K. B.; Smith, B. C.; O'Connor, M.; Mohrig, D. C.

2014-12-01

Coastal fluvial delta morphodynamics are prominently controlled by external fluvial sediment and water supplies; however, internal sediment-water-vegetation feedbacks are now being proposed as potentially equally significant in organizing and maintaining the progradation and aggradation of such systems. The time scales of fluvial and climate influences on these feedbacks, and of their responses, are also open questions. Historical remote sensing study of the Wax Lake Delta model system (Louisiana, USA) revealed trends in the evolution of the subaerial island surfaces from a non-systematic arrangement of elevations to a discrete set of levees and intra-island platforms with distinct vegetation types, designated as high marsh, low marsh, and mudflat habitat. We propose that this elevation zonation is consistent with multiple stable state theory, e.g. as applied to tidal salt marsh systems but not previously to deltas. According to zonally-distributed sediment core analyses, differentiation of island elevations was not due to organic matter accumulation as in salt marshes, but rather by differential mineral sediment accumulation with some organic contributions. Mineral sediment accumulation rates suggested that elevation growth was accelerating or holding steady over time, at least to date in this young delta, in contrast to theory suggesting rates should slow as elevation increases above mean water level. Hydrological analysis of island flooding suggested a prominent role of stochastic local storm events in raising island water levels and supplying mineral sediment to the subaerial island surfaces at short time scales; over longer time scales, the relative influences of local storms and inland/regional floods on the coupled sediment-water-vegetation system of the subaerial delta island surfaces remain the subject of ongoing study. These results help provide an empirical foundation for the next generation of coupled sediment-water-vegetation modeling and theory.

On the theory relating changes in area-average and pan evaporation (Invited)

NASA Astrophysics Data System (ADS)

Shuttleworth, W.; Serrat-Capdevila, A.; Roderick, M. L.; Scott, R.

2009-12-01

Theory relating changes in area-average evaporation with changes in the evaporation from pans or open water is developed. Such changes can arise by Type (a) processes related to large-scale changes in atmospheric concentrations and circulation that modify surface evaporation rates in the same direction, and Type (b) processes related to coupling between the surface and atmospheric boundary layer (ABL) at the landscape scale that usually modify area-average evaporation and pan evaporation in different directions. The interrelationship between evaporation rates in response to Type (a) changes is derived. They have the same sign and broadly similar magnitude but the change in area-average evaporation is modified by surface resistance. As an alternative to assuming the complementary evaporation hypothesis, the results of previous modeling studies that investigated surface-atmosphere coupling are parameterized and used to develop a theoretical description of Type (b) coupling via vapor pressure deficit (VPD) in the ABL. The interrelationship between appropriately normalized pan and area-average evaporation rates is shown to vary with temperature and wind speed but, on average, the Type (b) changes are approximately equal and opposite. Long-term Australian pan evaporation data are analyzed to demonstrate the simultaneous presence of Type (a) and (b) processes, and observations from three field sites in southwestern USA show support for the theory describing Type (b) coupling via VPD. England's victory over Australia in 2009 Ashes cricket test match series will not be mentioned.

Global-scale water circulation in the Earth's mantle: Implications for the mantle water budget in the early Earth

NASA Astrophysics Data System (ADS)

Nakagawa, Takashi; Spiegelman, Marc W.

2017-04-01

We investigate the influence of the mantle water content in the early Earth on that in the present mantle using numerical convection simulations that include three processes for redistribution of water: dehydration, partitioning of water into partially molten mantle, and regassing assuming an infinite water reservoir at the surface. These models suggest that the water content of the present mantle is insensitive to that of the early Earth. The initial water stored during planetary formation is regulated up to 1.2 OMs (OM = Ocean Mass; 1.4 ×1021 kg), which is reasonable for early Earth. However, the mantle water content is sensitive to the rheological dependence on the water content and can range from 1.2 to 3 OMs at the present day. To explain the evolution of mantle water content, we computed water fluxes due to subducting plates (regassing), degassing and dehydration. For weakly water dependent viscosity, the net water flux is almost balanced with those three fluxes but, for strongly water dependent viscosity, the regassing dominates the water cycle system because the surface plate activity is more vigorous. The increased convection is due to enhanced lubrication of the plates caused by a weak hydrous crust for strongly water dependent viscosity. The degassing history is insensitive to the initial water content of the early Earth as well as rheological strength. The degassing flux from Earth's surface is calculated to be approximately O (1013) kg /yr, consistent with a coupled model of climate evolution and mantle thermal evolution.

Development of a land surface model with coupled snow and frozen soil physics

NASA Astrophysics Data System (ADS)

Wang, Lei; Zhou, Jing; Qi, Jia; Sun, Litao; Yang, Kun; Tian, Lide; Lin, Yanluan; Liu, Wenbin; Shrestha, Maheswor; Xue, Yongkang; Koike, Toshio; Ma, Yaoming; Li, Xiuping; Chen, Yingying; Chen, Deliang; Piao, Shilong; Lu, Hui

2017-06-01

Snow and frozen soil are important factors that influence terrestrial water and energy balances through snowpack accumulation and melt and soil freeze-thaw. In this study, a new land surface model (LSM) with coupled snow and frozen soil physics was developed based on a hydrologically improved LSM (HydroSiB2). First, an energy-balance-based three-layer snow model was incorporated into HydroSiB2 (hereafter HydroSiB2-S) to provide an improved description of the internal processes of the snow pack. Second, a universal and simplified soil model was coupled with HydroSiB2-S to depict soil water freezing and thawing (hereafter HydroSiB2-SF). In order to avoid the instability caused by the uncertainty in estimating water phase changes, enthalpy was adopted as a prognostic variable instead of snow/soil temperature in the energy balance equation of the snow/frozen soil module. The newly developed models were then carefully evaluated at two typical sites of the Tibetan Plateau (TP) (one snow covered and the other snow free, both with underlying frozen soil). At the snow-covered site in northeastern TP (DY), HydroSiB2-SF demonstrated significant improvements over HydroSiB2-F (same as HydroSiB2-SF but using the original single-layer snow module of HydroSiB2), showing the importance of snow internal processes in three-layer snow parameterization. At the snow-free site in southwestern TP (Ngari), HydroSiB2-SF reasonably simulated soil water phase changes while HydroSiB2-S did not, indicating the crucial role of frozen soil parameterization in depicting the soil thermal and water dynamics. Finally, HydroSiB2-SF proved to be capable of simulating upward moisture fluxes toward the freezing front from the underlying soil layers in winter.

Development and assessment of an efficient vadose zone module solving the 1D Richards' equation and including root extraction by plants

NASA Astrophysics Data System (ADS)

Varado, N.; Braud, I.; Ross, P. J.

2006-05-01

From the non iterative numerical method proposed by [Ross, P.J., 2003. Modeling soil water and solute transport—fast, simplified numerical solutions. Agronomy Journal 95, 1352-1361] for solving the 1D Richards' equation, an unsaturated zone module for large scale hydrological model is developed by the inclusion of a root extraction module and a formulation of interception. Two root water uptake modules, first proposed by [Lai, C.-T. and Katul, G., 2000. The dynamic role of rott-water uptake in coupling potential to actual transpiration. Adv. Water Res. 23: 427-439; Li, K.Y., De Jong, R. and Boisvert, J.B., 2001. An exponential root-water-uptake model with water stress compensation. J. Hydrol. 252: 189-204], were included as the sink term in the Richards' equation. They express root extraction as a linear function of potential transpiration and take into account water stress and compensation mechanism allowing water to be extracted in wetter layers. The vadose zone module is tested in a systematic way with synthetic data sets covering a wide range of soil characteristics, climate forcing, and vegetation cover. A detailed SVAT model providing an accurate solution of the coupled heat and water transfer in the soil and the surface energy balance is used as a reference. The accuracy of the numerical solution using only the SVAT soil module, and the loss of accuracy when using a potential evapotranspiration instead of solving the energy budget are both investigated. The vadose zone module is very accurate with errors of less than a few percent for cumulative transpiration. Soil evaporation is less accurately simulated as it leads to a systematic underestimation of soil evaporation amounts. The [Lai, C.-T. and Katul, G., 2000. The dynamic role of rott-water uptake in coupling potential to actual transpiration. Adv. Water Res. 23: 427-439] module is not adapted for sandy soils, due to a weakness in the compensation term formulation. When using a potential evapotranspiration instead of the surface energy balance, we evidenced a difference in partitioning the energy between the soil and the vegetation. A Beer-Lambert law is not able to take into account the complex interactions at the soil-vegetation-atmopshere interface. However, under field conditions, the accuracy of the vadose zone module is satisfactory provided that a correct crop coefficient could be defined. As a conclusion the numerical method proposed by [Ross, P.J., 2003. Modeling soil water and solute transport—fast, simplified numerical solutions. Agronomy Journal 95, 1352-1361] coupled with the [Li, K.Y., De Jong, R. and Boisvert, J.B., 2001. An exponential root-water-uptake model with water stress compensation. J. Hydrol. 252: 189-204] root extraction module provides an efficient and accurate solution for inclusion as a physically-based infiltration-evapotranspiration module into larger scale watershed models.

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

PubMed

Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

Communication: Is a coarse-grained model for water sufficient to compute Kapitza conductance on non-polar surfaces?

PubMed

Ardham, Vikram Reddy; Leroy, Frédéric

2017-10-21

Coarse-grained models have increasingly been used in large-scale particle-based simulations. However, due to their lack of degrees of freedom, it is a priori unlikely that they straightforwardly represent thermal properties with the same accuracy as their atomistic counterparts. We take a first step in addressing the impact of liquid coarse-graining on interfacial heat conduction by showing that an atomistic and a coarse-grained model of water may yield similar values of the Kapitza conductance on few-layer graphene with interactions ranging from hydrophobic to mildly hydrophilic. By design the water models employed yield similar liquid layer structures on the graphene surfaces. Moreover, they share common vibration properties close to the surfaces and thus couple with the vibrations of graphene in a similar way. These common properties explain why they yield similar Kapitza conductance values despite their bulk thermal conductivity differing by more than a factor of two.

Simulating crop phenology in the Community Land Model and its impact on energy and carbon fluxes

USDA-ARS?s Scientific Manuscript database

A reasonable representation of crop phenology and biophysical processes in land surface models is necessary to accurately simulate energy, water and carbon budgets at the field, regional, and global scales. However, the evaluation of crop models that can be coupled to earth system models is relative...

Non-linear macro evolution of a dc driven micro atmospheric glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn

2015-10-15

We studied the macro evolution of the micro atmospheric glow discharge generated between a micro argon jet into ambient air and static water. The micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors are found for the micro discharge when the water acts as a cathode, different from the discharge when water behaves as an anode. Groups of snapshots of the micro discharge formed at different discharge currents are captured by an intensified charge-coupled device with controlled exposure time, and each group consisted of 256 images taken in succession. Edge detection methods are used to identify the water surfacemore » and then the total brightness is defined by adding up the signal counts over the area of the micro discharge. Motions of the water surface at different discharge currents show that the water surface lowers increasingly rapidly when the water acts as a cathode. In contrast, the water surface lowers at a constant speed when the water behaves as an anode. The light curves are similar to logistic growth curves, suggesting that a self-inhibition process occurs in the micro discharge. Meanwhile, the total brightness increases linearly during the same time when the water acts as an anode. Discharge-water interactions cause the micro discharge to evolve. The charged particle bomb process is probably responsible for the different behaviors of the micro discharges when the water acts as cathode and anode.« less

Initial and long-term bond strengths of one-step self-etch adhesives with silane coupling agent to enamel-dentin-composite in combined situation.

PubMed

Mamanee, Teerapong; Takahashi, Masahiro; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

2015-01-01

This study evaluated the effect of adding silane coupling agent on initial and long-term bond strengths of one-step self-etch adhesives to enamel-dentin-composite in combined situation. Cervical cavities were prepared on extracted molars and filled with Clearfil AP-X. After water-storage for one-week, the filled teeth were sectioned in halves to expose enamel, dentin and composite surfaces and then enamel-dentin-composite surface was totally applied with one of adhesive treatments (Clearfil SE One, Clearfil SE One with Clearfil Porcelain Bond Activator, Beautibond Multi, Beautibond Multi with Beautibond Multi PR Plus and Scotchbond Universal). After designed period, micro-shear bond strengths (µSBSs) to each substrate were determined. For each period of water-storage, additive silane treatments significantly increased µSBS to composite (p<0.001). On the other hand, they significantly decreased µSBS to dentin (p<0.001), although did not have adverse effect on µSBS to enamel (p>0.05). Moreover, the stability of µSBS was depended on materials and substrates used.

Hydrogeologic setting and conceptual hydrologic model of the Spring Creek basin, Centre County, Pennsylvania

USGS Publications Warehouse

Fulton, John W.; Koerkle, Edward H.; McAuley, Steven D.; Hoffman, Scott A.; Zarr, Linda F.

2005-01-01

The Spring Creek Basin, Centre County, Pa., is experiencing some of the most rapid growth and development within the Commonwealth. This trend has resulted in land-use changes and increased water use, which will affect the quantity and quality of stormwater runoff, surface water, ground water, and aquatic resources within the basin. The U.S. Geological Survey (USGS), in cooperation with the ClearWater Conservancy (CWC), Spring Creek Watershed Community (SCWC), and Spring Creek Watershed Commission (SCWCm), has developed a Watershed Plan (Plan) to assist decision makers in water-resources planning. One element of the Plan is to provide a summary of the basin characteristics and a conceptual model that incorporates the hydrogeologic characteristics of the basin. The report presents hydrogeologic data for the basin and presents a conceptual model that can be used as the basis for simulating surface-water and ground-water flow within the basin. Basin characteristics; sources of data referenced in this text; physical characteristics such as climate, physiography, topography, and land use; hydrogeologic characteristics; and water-quality characteristics are discussed. A conceptual model is a simplified description of the physical components and interaction of the surface- and ground-water systems. The purpose for constructing a conceptual model is to simplify the problem and to organize the available data so that the system can be analyzed accurately. Simplification is necessary, because a complete accounting of a system, such as Spring Creek, is not possible. The data and the conceptual model could be used in development of a fully coupled numerical model that dynamically links surface water, ground water, and land-use changes. The model could be used by decision makers to manage water resources within the basin and as a prototype that is transferable to other watersheds.

Modeling and simulation of ocean wave propagation using lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Nuraiman, Dian

2017-10-01

In this paper, we present on modeling and simulation of ocean wave propagation from the deep sea to the shoreline. This requires high computational cost for simulation with large domain. We propose to couple a 1D shallow water equations (SWE) model with a 2D incompressible Navier-Stokes equations (NSE) model in order to reduce the computational cost. The coupled model is solved using the lattice Boltzmann method (LBM) with the lattice Bhatnagar-Gross-Krook (BGK) scheme. Additionally, a special method is implemented to treat the complex behavior of free surface close to the shoreline. The result shows the coupled model can reduce computational cost significantly compared to the full NSE model.

Hydrology and phosphorus transport simulation in a lowland polder by a coupled modeling system.

PubMed

Yan, Renhua; Huang, Jiacong; Li, Lingling; Gao, Junfeng

2017-08-01

Modeling the rain-runoff processes and phosphorus transport processes in lowland polders is critical in finding reasonable measures to alleviate the eutrophication problem of downstream rivers and lakes. This study develops a lowland Polder Hydrology and Phosphorus modeling System (PHPS) by coupling the WALRUS-paddy model and an improved phosphorus module of a Phosphorus Dynamic model for lowland Polder systems (PDP). It considers some important hydrological characteristics, such as groundwater-unsaturated zone coupling, groundwater-surface water feedback, human-controlled irrigation and discharge, and detailed physical and biochemical cycles of phosphorus in surface water. The application of the model in the Jianwei polder shows that the simulated phosphorus matches well with the measured values. The high precision of this model combined with its low input data requirement and efficient computation make it practical and easy to the water resources management of Chinese polders. Parameter sensitivity analysis demonstrates that K uptake , c Q2 , c W1 , and c Q1 exert a significant effect on the modeled results, whereas K resuspensionMax , K settling , and K mineralization have little effect on the modeled total phosphorus. Among the three types of uncertainties (i.e., parameter, initial condition, and forcing uncertainties), forcing uncertainty produces the strongest effect on the simulated phosphorus. Based on the analysis result of annual phosphorus balance when considering the high import from irrigation and fertilization, lowland polder is capable of retaining phosphorus and reducing phosphorus export to surrounding aquatic ecosystems because of their special hydrological regulation regime. Copyright © 2016 Elsevier Ltd. All rights reserved.

Burial of gas-phase HNO(3) by growing ice surfaces under tropospheric conditions.

PubMed

Ullerstam, Maria; Abbatt, Jonathan P D

2005-10-21

The uptake of gas-phase nitric acid by ice surfaces undergoing growth by vapor deposition has been performed for the first time under conditions of the free troposphere. The investigation was performed using a coated-wall flow tube coupled to a chemical ionization mass spectrometer, at nitric acid partial pressures between 10(-7) and 10(-6) hPa, at 214, 229 and 239 K. Ice surfaces were prepared as smooth ice films from ultra-pure water. During the experiments an excess flow of water vapor was added to the carrier gas flow and the existing ice surfaces grew by depositing water vapor. The average growth rates ranged from 0.7-5 microm min(-1), values similar to those which prevail in some portions of the atmosphere. With growing ice the long term uptake of nitric acid is significantly enhanced compared to an experiment performed at equilibrium, i.e. at 100% relative humidity (RH) with respect to ice. The fraction of HNO(3) that is deposited onto the growing ice surface is independent of the growth rate and may be driven by the solubility of the nitric acid in the growing ice film rather than by condensation kinetics alone.

Modeling decadal timescale interactions between surface water and ground water in the central Everglades, Florida, USA

USGS Publications Warehouse

Harvey, J.W.; Newlin, J.T.; Krupa, S.L.

2006-01-01

Surface-water and ground-water flow are coupled in the central Everglades, although the remoteness of this system has hindered many previous attempts to quantify interactions between surface water and ground water. We modeled flow through a 43,000 ha basin in the central Everglades called Water Conservation Area 2A. The purpose of the model was to quantify recharge and discharge in the basin's vast interior areas. The presence and distribution of tritium in ground water was the principal constraint on the modeling, based on measurements in 25 research wells ranging in depth from 2 to 37 m. In addition to average characteristics of surface-water flow, the model parameters included depth of the layer of 'interactive' ground water that is actively exchanged with surface water, average residence time of interactive ground water, and the associated recharge and discharge fluxes across the wetland ground surface. Results indicated that only a relatively thin (8 m) layer of the 60 m deep surfical aquifer actively exchanges surface water and ground water on a decadal timescale. The calculated storage depth of interactive ground water was 3.1 m after adjustment for the porosity of peat and sandy limestone. Modeling of the tritium data yielded an average residence time of 90 years in interactive ground water, with associated recharge and discharge fluxes equal to 0.01 cm d -1. 3H/3He isotopic ratio measurements (which correct for effects of vertical mixing in the aquifer with deeper, tritium-dead water) were available from several wells, and these indicated an average residence time of 25 years, suggesting that residence time was overestimated using tritium measurements alone. Indeed, both residence time and storage depth would be expected to be overestimated due to vertical mixing. The estimate of recharge and discharge (0.01 cm d-1) that resulted from tritium modeling therefore is still considered reliable, because the ratio of residence time and storage depth (used to calculated recharge and discharge) is much less sensitive to vertical mixing compared with residence time alone. We conclude that a small but potentially significant component of flow through the Everglades is recharged to the aquifer and stored there for years to decades before discharged back to surface water. Long-term storage of water and solutes in the ground-water system beneath the wetlands has implications for restoration of Everglades water quality.

Modeling decadal timescale interactions between surface water and ground water in the central Everglades, Florida, USA

NASA Astrophysics Data System (ADS)

Harvey, Judson W.; Newlin, Jessica T.; Krupa, Steven L.

2006-04-01

Surface-water and ground-water flow are coupled in the central Everglades, although the remoteness of this system has hindered many previous attempts to quantify interactions between surface water and ground water. We modeled flow through a 43,000 ha basin in the central Everglades called Water Conservation Area 2A. The purpose of the model was to quantify recharge and discharge in the basin's vast interior areas. The presence and distribution of tritium in ground water was the principal constraint on the modeling, based on measurements in 25 research wells ranging in depth from 2 to 37 m. In addition to average characteristics of surface-water flow, the model parameters included depth of the layer of 'interactive' ground water that is actively exchanged with surface water, average residence time of interactive ground water, and the associated recharge and discharge fluxes across the wetland ground surface. Results indicated that only a relatively thin (8 m) layer of the 60 m deep surfical aquifer actively exchanges surface water and ground water on a decadal timescale. The calculated storage depth of interactive ground water was 3.1 m after adjustment for the porosity of peat and sandy limestone. Modeling of the tritium data yielded an average residence time of 90 years in interactive ground water, with associated recharge and discharge fluxes equal to 0.01 cm d -1. 3H/ 3He isotopic ratio measurements (which correct for effects of vertical mixing in the aquifer with deeper, tritium-dead water) were available from several wells, and these indicated an average residence time of 25 years, suggesting that residence time was overestimated using tritium measurements alone. Indeed, both residence time and storage depth would be expected to be overestimated due to vertical mixing. The estimate of recharge and discharge (0.01 cm d -1) that resulted from tritium modeling therefore is still considered reliable, because the ratio of residence time and storage depth (used to calculated recharge and discharge) is much less sensitive to vertical mixing compared with residence time alone. We conclude that a small but potentially significant component of flow through the Everglades is recharged to the aquifer and stored there for years to decades before discharged back to surface water. Long-term storage of water and solutes in the ground-water system beneath the wetlands has implications for restoration of Everglades water quality.

Dynamic coupled metal transport-speciation model: application to assess a zinc-contaminated lake.

PubMed

Bhavsar, Satyendra P; Diamond, Miriam L; Gandhi, Nilima; Nilsen, Joel

2004-10-01

A coupled metal transport and speciation/complexation model (TRANSPEC) has been developed to estimate the speciation and fate of multiple interconverting species in surface aquatic systems. Dynamic-TRANSPEC loosely, sequentially couples the speciation/complexation and fate modules that, for the unsteady state formulation, run alternatively at every time step. The speciation module first estimates species abundance using, in this version, MINEQL+ considering time-dependent changes in water and pore-water chemistry. The fate module is based on the quantitative water air sediment interaction (QWASI) model and fugacity/aquivalence formulation, with the option of using a pseudo-steady state solution to account for past discharges. Similarly to the QWASI model for organic contaminants, TRANSPEC assumes the instantaneous equilibrium distribution of metal species among dissolved, colloidal, and particulate phases based on ambient chemistry parameters that can be collected through conventional field methods. The model is illustrated with its application to Ross Lake (Manitoba, Canada) that has elevated Zn concentrations due to discharges over 70 years from a mining operation. Using measurements from field studies, the model reproduces year-round variations in Zn water concentrations. A 10-year projection for current conditions suggests decreasing Zn remobilization and export from the lake. Decreasing Zn loadings increases sediment-to-water transport but decreases water concentrations, and vice versa. Species distribution is affected by pH such that a decrease in pH increases metal export from the lake and vice versa.

Spatially complex distribution of dissolved manganese in a fjord as revealed by high-resolution in situ sensing using the autonomous underwater vehicle Autosub.

PubMed

Statham, P J; Connelly, D P; German, C R; Brand, T; Overnell, J O; Bulukin, E; Millard, N; McPhail, S; Pebody, M; Perrett, J; Squire, M; Stevenson, P; Webb, A

2005-12-15

Loch Etive is a fjordic system on the west coast of Scotland. The deep waters of the upper basin are periodically isolated, and during these periods oxygen is lost through benthic respiration and concentrations of dissolved manganese increase. In April 2000 the autonomous underwater vehicle (AUV) Autosub was fitted with an in situ dissolved manganese analyzer and was used to study the spatial variability of this element together with oxygen, salinity, and temperature throughout the basin. Six along-loch transects were completed at either constant height above the seafloor or at constant depth below the surface. The ca. 4000 in situ 10-s-average dissolved Mn (Mnd) data points obtained provide a new quasi-synoptic and highly detailed view of the distribution of manganese in this fjordic environment not possible using conventional (water bottle) sampling. There is substantial variability in concentrations (<25 to >600 nM) and distributions of Mnd. Surface waters are characteristically low in Mnd reflecting mixing of riverine and marine end-member waters, both of which are low in Mnd. The deeper waters are enriched in Mnd, and as the water column always contains some oxygen, this must reflect primarily benthic inputs of reduced dissolved Mn. However, this enrichment of Mnd is spatially very variable, presumably as a result of variability in release of Mn coupled with mixing of water in the loch and removal processes. This work demonstrates how AUVs coupled with chemical sensors can reveal substantial small-scale variability of distributions of chemical species in coastal environments that would not be resolved by conventional sampling approaches. Such information is essential if we are to improve our understanding of the nature and significance of the underlying processes leading to this variability.

Estimating discharge and non-point source nitrate loading to streams from three end-member pathways using high-frequency water quality and streamflow data

NASA Astrophysics Data System (ADS)

Miller, M. P.; Tesoriero, A. J.; Hood, K.; Terziotti, S.; Wolock, D.

2017-12-01

The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high-frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the coupled groundwater-surface water system. A new approach for separating the streamflow hydrograph into three components was developed and coupled with high-frequency specific conductance and nitrate data to estimate time-variable watershed-scale nitrate loading from three end-member pathways - dilute quickflow, concentrated quickflow, and slowflow groundwater - to two streams in central Wisconsin. Time-variable nitrate loads from the three pathways were estimated for periods of up to two years in a groundwater-dominated and a quickflow-dominated stream, using only streamflow and in-stream water quality data. The dilute and concentrated quickflow end-members were distinguished using high-frequency specific conductance data. Results indicate that dilute quickflow contributed less than 5% of the nitrate load at both sites, whereas 89±5% of the nitrate load at the groundwater-dominated stream was from slowflow groundwater, and 84±13% of the nitrate load at the quickflow-dominated stream was from concentrated quickflow. Concentrated quickflow nitrate concentrations varied seasonally at both sites, with peak concentrations in the winter that were 2-3 times greater than minimum concentrations during the growing season. Application of this approach provides an opportunity to assess stream vulnerability to non-point source nitrate loading and expected stream responses to current or changing conditions and practices in watersheds.

Estimating Discharge and Nonpoint Source Nitrate Loading to Streams From Three End-Member Pathways Using High-Frequency Water Quality Data

NASA Astrophysics Data System (ADS)

Miller, Matthew P.; Tesoriero, Anthony J.; Hood, Krista; Terziotti, Silvia; Wolock, David M.

2017-12-01

The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high-frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the coupled groundwater-surface water system. A new approach for separating the streamflow hydrograph into three components was developed and coupled with high-frequency nitrate data to estimate time-variable nitrate loads from chemically dilute quick flow, chemically concentrated quick flow, and slowflow groundwater end-member pathways for periods of up to 2 years in a groundwater-dominated and a quick-flow-dominated stream in central Wisconsin, using only streamflow and in-stream water quality data. The dilute and concentrated quick flow end-members were distinguished using high-frequency specific conductance data. Results indicate that dilute quick flow contributed less than 5% of the nitrate load at both sites, whereas 89 ± 8% of the nitrate load at the groundwater-dominated stream was from slowflow groundwater, and 84 ± 25% of the nitrate load at the quick-flow-dominated stream was from concentrated quick flow. Concentrated quick flow nitrate concentrations varied seasonally at both sites, with peak concentrations in the winter that were 2-3 times greater than minimum concentrations during the growing season. Application of this approach provides an opportunity to assess stream vulnerability to nonpoint source nitrate loading and expected stream responses to current or changing conditions and practices in watersheds.

Hydrological Modelling of The Guadiana Basin

NASA Astrophysics Data System (ADS)

Conan, C.; Bouraoui, F.; de Marsily, G.; Bidoglio, G.

Increased anthropogenic activities such as agriculture, irrigation, industry, mining, ur- ban water supply and sewage treatment, have created significant environmental prob- lems. To ensure sustainable development of water resources, water managers need new strategies and suitable tools. In particular it is often compulsory that surface wa- ter and groundwater be managed simultaneously both in terms of quantity and quality at catchment scales. To this purpose, a model coupling SWAT (Soil and Water As- sessment Tool) and MODFLOW (Modular 3-D Flow model) was developed. SWAT is a quasi-distributed watershed model with a GIS interface that outlines the sub-basins and stream networks from a Digital Elevation Model (DEM) and calculates daily wa- ter balances from meteorological data, soil and land-use characteristics. The particular advantage of this model, compared to other fully distributed physically based mod- els, is that it requires a small amount of readily available input data. MODFLOW is a fully distributed model that calculates groundwater flow from aquifer characteris- tics. We have adapted this new coupled model SWAT-MODFLOW to a Mediterranean catchment, the Guadiana basin, and present the first results of this work. Only wa- ter quantity results are available at this stage. The validation consisted in comparing measured and predicted daily flow at the catchment and sub-catchment outlets for the period 1970-1995. The model accurately reproduced the decrease of the piezometric level, due to increased water abstraction, and the exchanges between surface water and ground-water. The sensitivity of the model to irrigation practices was evaluated. The usefulness of this model as a management tool has been illustrated through the analysis of alternative scenarios of agricultural practices and climate change.

Understanding Drought and Regional Conservation Efforts on Urban Ecohydrology in Southern California

NASA Astrophysics Data System (ADS)

Hogue, T. S.

2015-12-01

Cities in the western U.S. are under increasing pressure to reduce the demand of imported water through increasing conservation efforts, altering non-native landscapes, and enhancing local water supplies. The State of California adopted emergency regulations implementing a mandatory 25% statewide reduction in potable urban water use and agricultural restrictions have also been enacted. The complexities in urban water flows and lack of granular data make understanding the impact of conservation and demand change on regional ecohydrology difficult. This presentation highlights ongoing work to better understand the coupling between humans, water and ecosystems in semi-arid urban cities, using metropolitan southern California as a case study. We evaluate historical and contemporary ecohydrologic behavior and human impacts through intensive data collection, remote sensing and high resolution modeling. The change in outdoor irrigation rates due to recent conservation measures (2008-2010) has resulted in overall decreased greenness and reduced dry season streamflow; however significant variability in conservation response is observed. Groundwater recharge, artificially supported by landscape irrigation, is also being impacted. In general, anthropogenic water fluxes (irrigation, pipe leakage, spreading grounds) are not parameterized in hydrologic and land surface models applied over urban areas. Inclusion of landscape irrigation significantly improves neighborhood scale simulations of evaporative fluxes and land surface temperatures and results in shifts in the energy partitioning. The cooling effects of irrigation on daily air temperatures has the largest influence over low intensity residential areas, with an average 2°C decrease observed in coupled model simulations (WRF-Noah-UCM). Ultimately, we strive to improve predictions of human-water interactions in semi-arid cities to better understand the effectiveness and impacts of ongoing drought and conservation efforts and guide demand strategies under future climate variability.

Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores

DOE PAGES

Dong, Xiquan; Schwantes, Adam C.; Xi, Baike; ...

2015-06-10

Here, six coupled and decoupled marine boundary layer (MBL) clouds were chosen from the 19 month Atmospheric Radiation Measurement Mobile Facility data set over the Azores. Thresholds of liquid water potential temperature difference Δθ L < 0.5 K (>0.5 K) and total water mixing ratio difference Δq t < 0.5 g/kg (>0.5 g/kg) below the cloud base were used for selecting the coupled (decoupled) cases. A schematic diagram was given to demonstrate the coupled and decoupled MBL vertical structures and how they associate with nondrizzle, virga, and rain drizzle events. Out of a total of 2676 5 min samples, 34.5%more » were classified as coupled and 65.5% as decoupled, 36.2% as nondrizzle and 63.8% as drizzle (47.7% as virga and 16.1% as rain), and 33.4% as daytime and 66.6% as nighttime. The decoupled cloud layer is deeper (0.406 km) than coupled cloud layer (0.304 km), and its liquid water path and cloud droplet effective radius (r e) values (122.1 gm -2 and 13.0 µm) are higher than coupled ones (83.7 gm -2 and 10.4 µm). Conversely, decoupled stratocumuli have lower cloud droplet number concentration (N d) and surface cloud condensation nucleus (CCN) concentration (N CCN) (74.5 cm -3 and 150.9 cm -3) than coupled stratocumuli (111.7 cm -3 and 216.4 cm -3). The linear regressions between r e and N d with N CCN have demonstrated that coupled r e and N d strongly depend on N CCN and have higher correlations (-0.56 and 0.59) with N CCN than decoupled results (-0.14 and 0.25). The MBL cloud properties under nondrizzle and virga drizzle conditions are similar to each other but significantly different to those of rain drizzle.« less

Light-Guided Surface Engineering for Biomedical Applications

PubMed Central

Jayagopal, Ashwath; Stone, Gregory P.; Haselton, Frederick R.

2010-01-01

Free radical species generated through fluorescence photobleaching have been reported to effectively couple a water-soluble species to surfaces containing electron-rich sites (1). In this report, we expand upon this strategy to control the patterned attachment of antibodies and peptides to surfaces for biosensing and tissue engineering applications. In the first application, we compare hydrophobic attachment and photobleaching methods to immobilize FITC-labeled anti-M13K07 bacteriophage antibodies to the SiO2 layer of a differential capacitive biosensor and to the polyester filament of a feedback-controlled filament array. On both surfaces, antibody attachment and function were superior to the previously employed hydrophobic attachment. Furthermore, a laser scanning confocal microscope could be used for automated, software-guided photoattachment chemistry. In a second application, the cell-adhesion peptide RGDS was site-specifically photocoupled to glass coated with fluorescein-conjugated poly(ethylene glycol). RGDS attachment and bioactivity were characterized by a fibroblast adhesion assay. Cell adhesion was limited to sites of RGDS photocoupling. These examples illustrate that fluorophore-based photopatterning can be achieved by both solution-phase fluorophores or surface-adhered fluorophores. The coupling preserves the bioactivity of the patterned species, is amenable to a variety of surfaces, and is readily accessible to laboratories with fluorescence imaging equipment. The flexibility offered by visible light patterning will likely have many useful applications in bioscreening and tissue engineering where the controlled placement of biomolecules and cells is critical, and should be considered as an alternative to chemical coupling methods. PMID:18314938

Application of a coupled ecosystem-chemical equilibrium model, DayCent-Chem, to stream and soil chemistry in a Rocky Mountain watershed

USGS Publications Warehouse

Hartman, M.D.; Baron, Jill S.; Ojima, D.S.

2007-01-01

Atmospheric deposition of sulfur and nitrogen species have the potential to acidify terrestrial and aquatic ecosystems, but nitrate and ammonium are also critical nutrients for plant and microbial productivity. Both the ecological response and the hydrochemical response to atmospheric deposition are of interest to regulatory and land management agencies. We developed a non-spatial biogeochemical model to simulate soil and surface water chemistry by linking the daily version of the CENTURY ecosystem model (DayCent) with a low temperature aqueous geochemical model, PHREEQC. The coupled model, DayCent-Chem, simulates the daily dynamics of plant production, soil organic matter, cation exchange, mineral weathering, elution, stream discharge, and solute concentrations in soil water and stream flow. By aerially weighting the contributions of separate bedrock/talus and tundra simulations, the model was able to replicate the measured seasonal and annual stream chemistry for most solutes for Andrews Creek in Loch Vale watershed, Rocky Mountain National Park. Simulated soil chemistry, net primary production, live biomass, and soil organic matter for forest and tundra matched well with measurements. This model is appropriate for accurately describing ecosystem and surface water chemical response to atmospheric deposition and climate change. ?? 2006 Elsevier B.V. All rights reserved.

New insights into the adsorption of 3-(trimethoxysilyl)propylmethacrylate on hydroxylated ZnO nanopowders.

PubMed

Bressy, Christine; Ngo, Van Giang; Ziarelli, Fabio; Margaillan, André

2012-02-14

Functionalization of zinc oxide (ZnO) nano-objects by silane grafting is an attractive method to provide nanostructured materials with a variety of surface properties. Active hydroxyl groups on the oxide surface are one of the causes governing the interfacial bond strength in nanohybrid particles. Here, "as-prepared" and commercially available zinc oxide nanopowders with a wide range of surface hydroxyl density were functionalized by a well-known polymerizable silane coupling agent, i.e., 3-(trimethoxysilyl)propylmethacrylate (MPS). Fourier transform infrared (FTIR) and solid-state (13)C and (29)Si nuclear magnetic resonance (NMR) spectroscopic investigations demonstrated that the silane coupling agent was fully hydrolyzed and linked to the hydroxyl groups already present on the particle surface through covalent and hydrogen bonds. Due to a basic catalyzed condensation of MPS with water, a siloxane layer was shown to be anchored to the nanoparticles through mono- and tridentate structures. Quantitative investigations were performed by thermogravimetric (TGA) and elemental analyses. The amount of silane linked to ZnO particles was shown to be affected by the amount of isolated hydroxyl groups available to react on the particle surface. For as-prepared ZnO nanoparticles, the number of isolated and available hydroxyl groups per square nanometer was up to 3 times higher than the one found on commercially available ZnO nanoparticles, leading to higher amounts of polymerizable silane agent linked to the surface. The MPS molecules were shown to be mainly oriented perpendicular to the oxide surface for all the as-prepared ZnO nanoparticles, whereas a parallel orientation was found for the preheated commercially ZnO nanopowders. In addition, ZnO nanoparticles were shown to be hydrophobized by the MPS treatment with water contact angles higher than 60°.

Watershed Scale Analysis of Groundwater Surface Water Interactions and Its Application to Conjunctive Management under Climatic and Anthropogenic Stresses over the US Sunbelt

NASA Astrophysics Data System (ADS)

Seo, Seung Beom

Although water is one of the most essential natural resources, human activities have been exerting pressure on water resources. In order to reduce these stresses on water resources, two key issues threatening water resources sustainability - interaction between surface water and groundwater resources and groundwater withdrawal impacts of streamflow depletion - were investigated in this study. First, a systematic decomposition procedure was proposed for quantifying the errors arising from various sources in the model chain in projecting the changes in hydrologic attributes using near-term climate change projections. Apart from the unexplained changes by GCMs, the process of customizing GCM projections to watershed scale through a model chain - spatial downscaling, temporal disaggregation and hydrologic model - also introduces errors, thereby limiting the ability to explain the observed changes in hydrologic variability. Towards this, we first propose metrics for quantifying the errors arising from different steps in the model chain in explaining the observed changes in hydrologic variables (streamflow, groundwater). The proposed metrics are then evaluated using a detailed retrospective analyses in projecting the changes in streamflow and groundwater attributes in four target basins that span across a diverse hydroclimatic regimes over the US Sunbelt. Our analyses focused on quantifying the dominant sources of errors in projecting the changes in eight hydrologic variables - mean and variability of seasonal streamflow, mean and variability of 3-day peak seasonal streamflow, mean and variability of 7-day low seasonal streamflow and mean and standard deviation of groundwater depth - over four target basins using an Penn state Integrated Hydrologic Model (PIHM) between the period 1956-1980 and 1981-2005. Retrospective analyses show that small/humid (large/arid) basins show increased (reduced) uncertainty in projecting the changes in hydrologic attributes. Further, changes in error due to GCMs primarily account for the unexplained changes in mean and variability of seasonal streamflow. On the other hand, the changes in error due to temporal disaggregation and hydrologic model account for the inability to explain the observed changes in mean and variability of seasonal extremes. Thus, the proposed metrics provide insights on how the error in explaining the observed changes being propagated through the model under different hydroclimatic regimes. To understand interaction between surface water and groundwater resources, transient pumping impacts on streamflow and groundwater level were analyzed by imposing shortterm pumping scenarios under historic drought conditions. Since surface water and groundwater systems are fully coupled and integrated systems, increased groundwater withdrawal during drought may reduce baseflow into the stream and prolong both systems' recovery from drought. Towards this, we proposed an uncertainty framework to understand the resiliency of groundwater and surface water systems using a fully-coupled hydrologic model under transient pumping. Using this framework, we quantified the restoration time of surface water and groundwater systems and also estimated the changes in the state variables after pumping. Groundwater pumping impacts over the watershed were also analyzed under different pumping volumes and different potential climate scenarios. Our analyses show that groundwater restoration time is more sensitive to changes in pumping volumes as opposed to changes in climate. After the cessation of pumping, streamflow recovers quickly in comparison to groundwater. Pumping impacts on other state variables are also discussed. Given that surface water and groundwater are inter-connected, optimal management of the both resources should be considered to improve the watershed resiliency under drought. Subsequently, conjunctive use of surface water and groundwater has been considered as an effective approach to mitigate water shortage problems that are primarily caused by a drought. It is found that appropriate use of groundwater withdrawal was able to reduce water scarcity in surface water resources in drought condition. Besides, recovery time constraint was embedded in the management model so that trade-off between minimizing water scarcity and maximizing sustainability on groundwater was successfully addressed.

Coupling the snow thermodynamic model SNOWPACK with the microwave emission model of layered snowpacks for subarctic and arctic snow water equivalent retrievals

NASA Astrophysics Data System (ADS)

Langlois, A.; Royer, A.; Derksen, C.; Montpetit, B.; Dupont, F.; GoïTa, K.

2012-12-01

Satellite-passive microwave remote sensing has been extensively used to estimate snow water equivalent (SWE) in northern regions. Although passive microwave sensors operate independent of solar illumination and the lower frequencies are independent of atmospheric conditions, the coarse spatial resolution introduces uncertainties to SWE retrievals due to the surface heterogeneity within individual pixels. In this article, we investigate the coupling of a thermodynamic multilayered snow model with a passive microwave emission model. Results show that the snow model itself provides poor SWE simulations when compared to field measurements from two major field campaigns. Coupling the snow and microwave emission models with successive iterations to correct the influence of snow grain size and density significantly improves SWE simulations. This method was further validated using an additional independent data set, which also showed significant improvement using the two-step iteration method compared to standalone simulations with the snow model.

A Coupled THMC model of FEBEX mock-up test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Liange; Samper, Javier

2008-09-15

FEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project for the engineered barrier system (EBS) of a radioactive waste repository in granite. It includes two full-scale heating and hydration tests: the in situ test performed at Grimsel (Switzerland) and a mock-up test operating at CIEMAT facilities in Madrid (Spain). The mock-up test provides valuable insight on thermal, hydrodynamic, mechanical and chemical (THMC) behavior of EBS because its hydration is controlled better than that of in situ test in which the buffer is saturated with water from the surrounding granitic rock. Here we present a coupled THMC model ofmore » the mock-up test which accounts for thermal and chemical osmosis and bentonite swelling with a state-surface approach. The THMC model reproduces measured temperature and cumulative water inflow data. It fits also relative humidity data at the outer part of the buffer, but underestimates relative humidities near the heater. Dilution due to hydration and evaporation near the heater are the main processes controlling the concentration of conservative species while surface complexation, mineral dissolution/precipitation and cation exchanges affect significantly reactive species as well. Results of sensitivity analyses to chemical processes show that pH is mostly controlled by surface complexation while dissolved cations concentrations are controlled by cation exchange reactions.« less

Towards an improved and more flexible representation of water stress in coupled photosynthesis-stomatal conductance models; implications for simulated land surface fluxes and variables at various spatiotemporal scales

NASA Astrophysics Data System (ADS)

Egea, G.; Verhoef, A.; Vidale, P. L.; Black, E.; Van den Hoof, C.

2012-04-01

Coupled photosynthesis-stomatal conductance (A-gs) models are commonly used in ecosystem models to represent the exchange rate of CO2 and H2O between vegetation and the atmosphere. The ways these models account for water stress differ greatly among modelling schemes. This study provides insight into the impact of contrasting model configurations of water stress on the simulated leaf-level values of net photosynthesis (A), stomatal conductance (gs), the functional relationship among them and their ratio, the intrinsic water use efficiency (A/gs), as soil dries. A simple, yet versatile, normalized soil moisture dependent function was used to account for the effects of water stress on gs, on mesophyll conductance (gm ) and on the biochemical capacity (Egea et al., 2011). Model output was compared to leaf-level values obtained from the literature. The sensitivity analyses emphasized the necessity to combine both stomatal and non-stomatal limitations of A in coupled A-gs models to accurately capture the observed functional relationships A vs. gs and A/gs vs. gs in response to drought. Accounting for water stress in coupled A-gs models by imposing either stomatal or biochemical limitations of A, as commonly practiced in most ecosystem models, failed to reproduce the observed functional relationship between key leaf gas exchange attributes. A quantitative limitation analysis revealed that the general pattern of C3 photosynthetic response to water stress can be represented in coupled A-gs models by imposing the highest limitation strength to mesophyll conductance, then to stomatal conductance and finally to the biochemical capacity. This more realistic representation of soil water stress on the simulated leaf-level values of A and gs was embedded in the JULES (Joint UK Land Environment Simulator; Best et al., 2011), model and tested for a number of vegetation types, for which driving and flux verification data were available. These simulations provide an insight into the effect that the revised parameterization will have on GCM simulations of climate variability and change. Best, M. J. et al. (2011). The Joint UK Land Environment Simulator (JULES), model description - Part 1: Energy and water fluxes. Geosci. Model Dev., 4, 677-699. Egea, G., Verhoef, A., Vidale, P.L. (2011) Towards an improved and more flexible representation of water stress in coupled photosynthesis-stomatal conductance models. Agricultural and Forest Meteorology, 151 (10), 1370-1384.

Regional Climate Simulations of the Hydrological Cycle in the Iberian Peninsula with a Coupled WRF-HYDRO Model

NASA Astrophysics Data System (ADS)

Rios-Entenza, A.; Miguez-Macho, G.

2008-12-01

Land-atmosphere water exchanges and heat fluxes play an important role in climate and particularly in controlling precipitation in water-limited regions. One of such regions is the Iberian Peninsula, and in this study we examine the relevance of water recycling in convective precipitation regimes of the Fall and Spring there, when rainfall is critical for agriculture and many other human activities. We conducted simulations with WRF-ARW model at 5 km horizontal resolution, using a 1500 km x 1500 km nested grid that covers the Iberian Peninsula, with a parent domain that uses spectral nudging in order to avoid the distortion of the large-scale circulation caused by the interaction of the modeled flow with the lateral boundaries of the nested grid. For land-surface interactions we coupled WRF with the LEAF-HYDRO land surface model, which includes water table dynamics. We use therefore a tool that simulates the entire water cycle, including the water table, which has been reported to be critical for soil moisture dynamics in semi-arid regions like the Iberian Peninsula. For each one of the events that we selected, we performed two simulations: a control one, where all land-atmosphere feedbacks are taken into account, and the experiment, where infiltration of the precipitated water into the soil was suppressed. In this manner we explore the role of upward latent and sensible heat fluxes and evapotranspiration in precipitation dynamics. Preliminary results suggest that water recycling is a key factor in extending convective precipitation during several days, and that the total new water added in the area as a whole is only a fraction of the total measured rainfall. An estimation of this fraction is very important to better understanding the water budget and for hydrological planning in this water-stressed region.

Predicting aerodynamic characteristics of vortical flows on three-dimensional configurations using a surface-singularity panel method

NASA Technical Reports Server (NTRS)

Maskew, B.

1983-01-01

A general low-order surface-singularity panel method is used to predict the aerodynamic characteristics of a problem where a wing-tip vortex from one wing closely interacts with an aft mounted wing in a low Reynolds Number flow; i.e., 125,000. Nonlinear effects due to wake roll-up and the influence of the wings on the vortex path are included in the calculation by using a coupled iterative wake relaxation scheme. The interaction also affects the wing pressures and boundary layer characteristics: these effects are also considered using coupled integral boundary layer codes and preliminary calculations using free vortex sheet separation modelling are included. Calculated results are compared with water tunnel experimental data with generally remarkably good agreement.

Role of cavitation in high-speed droplet impact problems

NASA Astrophysics Data System (ADS)

Kondo, Tomoki; Ando, Keita

2014-11-01

High-speed droplet impact is found in physical cleaning using liquid jets, but its mechanisms for particle removal from target surfaces are yet unclear. In this study, we explore the possibility of having cavitation inside the droplet. The pressure evolution within a droplet colliding with a flat surface of deformable materials is determined by multicomponent Euler equations. Dynamics of cavitation bubbles heterogeneously nucleated from preexisting nuclei are determined from Rayleigh-Plesset calculations according to the pressure evolution within the droplet in one-way-coupling manner. The simulation shows that cavitation indeed occurs due to tension that arises from the water hammer shock reflection at the droplet interface. The role of cavitation including pressure emission from its collapse is to be discussed based on the one-way-coupling computations.

Hydroelectromechanical modelling of a piezoelectric wave energy converter

NASA Astrophysics Data System (ADS)

Renzi, E.

2016-11-01

We investigate the hydroelectromechanical-coupled dynamics of a piezoelectric wave energy converter. The converter is made of a flexible bimorph plate, clamped at its ends and forced to motion by incident ocean surface waves. The piezoceramic layers are connected in series and transform the elastic motion of the plate into useful electricity by means of the piezoelectric effect. By using a distributed-parameter analytical approach, we couple the linear piezoelectric constitutive equations for the plate with the potential-flow equations for the surface water waves. The resulting system of governing partial differential equations yields a new hydroelectromechanical dispersion relation, whose complex roots are determined with a numerical approach. The effect of the piezoelectric coupling in the hydroelastic domain generates a system of short- and long-crested weakly damped progressive waves travelling along the plate. We show that the short-crested flexural wave component gives a dominant contribution to the generated power. We determine the hydroelectromechanical resonant periods of the device, at which the power output is significant.

Seismic moulin tremor

NASA Astrophysics Data System (ADS)

Roeoesli, Claudia; Walter, Fabian; Ampuero, Jean-Paul; Kissling, Edi

2016-08-01

Through glacial moulins, meltwater is routed from the glacier surface to its base. Moulins are a main feature feeding subglacial drainage systems and thus influencing basal motion and ice dynamics, but their geometry remains poorly known. Here we show that analysis of the seismic wavefield generated by water falling into a moulin can help constrain its geometry. We present modeling results of hour-long seimic tremors emitted from a vertical moulin shaft, observed with a seismometer array installed at the surface of the Greenland Ice Sheet. The tremor was triggered when the moulin water level exceeded a certain height, which we associate with the threshold for the waterfall to hit directly the surface of the moulin water column. The amplitude of the tremor signal changed over each tremor episode, in close relation to the amount of inflowing water. The tremor spectrum features multiple prominent peaks, whose characteristic frequencies are distributed like the resonant modes of a semiopen organ pipe and were found to depend on the moulin water level, consistent with a source composed of resonant tube waves (water pressure waves coupled to elastic deformation of the moulin walls) along the water-filled moulin pipe. Analysis of surface particle motions lends further support to this interpretation. The seismic wavefield was modeled as a superposition of sustained wave radiation by pressure sources on the side walls and at the bottom of the moulin. The former was found to dominate the wave field at close distance and the latter at large distance to the moulin.

Some Properties of Composite Panels Made from Wood Flour and Recycled Polyethylene

PubMed Central

Ozdemir, Turgay; Mengeloglu, Fatih

2008-01-01

This study investigated the effect of board type (unmodified vs. MAPE modified) on the surface quality and thickness swelling-water absorption properties of recycled high density polyethylene (HDPE) based wood plastic composites. Additionally, two commercially available coatings (cellulosic coating and polyurethane lacquer coating) were also applied to composite surfaces and their adhesion strength, abrasion and scratch resistance, and gloss values were determined. This study showed that modification of the composites with MAPE coupling agent increased the surface smoothness and reduced the water absorption and thickness swelling of the panels. Abrasion resistance of the composites was also improved through MAPE modification. Regardless of board type, higher scratch resistance and gloss values were observed for polyurethane lacquer coated samples compared to those of cellulosic varnish coated ones. Improvement of adhesion strength was also seen on SEM micrographs. PMID:19330092

Microwave Extraction of Volatiles for Mars Science and ISRU

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaulker, William F.

2012-01-01

The greatest advantage of microwave heating for volatiles extraction is that excavation can be greatly reduced. Surface support operations would be simple consisting of rovers with drilling capability for insertion of microwaves down bore holes to heat at desired depths. The rovers would also provide support to scientific instruments for volatiles analysis and for volatiles collection and storage. The process has the potential for a much lower mass and a less complex system than other in-situ processes. Microwave energy penetrates the surface heating within with subsequent sublimation of water or decomposition of volatile containing minerals. On Mars the volatiles should migrate to the surface to be captured with a cold trap. The water extraction and transport process coupled with atmospheric CO2 collection could readily lead to a propellant production process, H2O + CO2 yields CH4 + O2.

Condensation on slippery asymmetric bumps

NASA Astrophysics Data System (ADS)

Park, Kyoo-Chul; Kim, Philseok; Grinthal, Alison; He, Neil; Fox, David; Weaver, James C.; Aizenberg, Joanna

2016-03-01

Controlling dropwise condensation is fundamental to water-harvesting systems, desalination, thermal power generation, air conditioning, distillation towers, and numerous other applications. For any of these, it is essential to design surfaces that enable droplets to grow rapidly and to be shed as quickly as possible. However, approaches based on microscale, nanoscale or molecular-scale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach—based on principles derived from Namib desert beetles, cacti, and pitcher plants—that synergistically combines these aspects of condensation and substantially outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle’s bumpy surface geometry in promoting condensation, and using theoretical modelling, we show how to maximize vapour diffusion fluxat the apex of convex millimetric bumps by optimizing the radius of curvature and cross-sectional shape. Integrating this apex geometry with a widening slope, analogous to cactus spines, directly couples facilitated droplet growth with fast directional transport, by creating a free-energy profile that drives the droplet down the slope before its growth rate can decrease. This coupling is further enhanced by a slippery, pitcher-plant-inspired nanocoating that facilitates feedback between coalescence-driven growth and capillary-driven motion on the way down. Bumps that are rationally designed to integrate these mechanisms are able to grow and transport large droplets even against gravity and overcome the effect of an unfavourable temperature gradient. We further observe an unprecedented sixfold-higher exponent of growth rate, faster onset, higher steady-state turnover rate, and a greater volume of water collected compared to other surfaces. We envision that this fundamental understanding and rational design strategy can be applied to a wide range of water-harvesting and phase-change heat-transfer applications.

Simulating adsorption of U(VI) under transient groundwater flow and hydrochemistry: Physical versus chemical nonequilibrium model

USGS Publications Warehouse

Greskowiak, J.; Hay, M.B.; Prommer, H.; Liu, C.; Post, V.E.A.; Ma, R.; Davis, J.A.; Zheng, C.; Zachara, J.M.

2011-01-01

Coupled intragrain diffusional mass transfer and nonlinear surface complexation processes play an important role in the transport behavior of U(VI) in contaminated aquifers. Two alternative model approaches for simulating these coupled processes were analyzed and compared: (1) the physical nonequilibrium approach that explicitly accounts for aqueous speciation and instantaneous surface complexation reactions in the intragrain regions and approximates the diffusive mass exchange between the immobile intragrain pore water and the advective pore water as multirate first-order mass transfer and (2) the chemical nonequilibrium approach that approximates the diffusion-limited intragrain surface complexation reactions by a set of multiple first-order surface complexation reaction kinetics, thereby eliminating the explicit treatment of aqueous speciation in the intragrain pore water. A model comparison has been carried out for column and field scale scenarios, representing the highly transient hydrological and geochemical conditions in the U(VI)-contaminated aquifer at the Hanford 300A site, Washington, USA. It was found that the response of U(VI) mass transfer behavior to hydrogeochemically induced changes in U(VI) adsorption strength was more pronounced in the physical than in the chemical nonequilibrium model. The magnitude of the differences in model behavior depended particularly on the degree of disequilibrium between the advective and immobile phase U(VI) concentrations. While a clear difference in U(VI) transport behavior between the two models was noticeable for the column-scale scenarios, only minor differences were found for the Hanford 300A field scale scenarios, where the model-generated disequilibrium conditions were less pronounced as a result of frequent groundwater flow reversals. Copyright 2011 by the American Geophysical Union.

Uncertainties in modelling the climate impact of irrigation

NASA Astrophysics Data System (ADS)

de Vrese, Philipp; Hagemann, Stefan

2017-11-01

Irrigation-based agriculture constitutes an essential factor for food security as well as fresh water resources and has a distinct impact on regional and global climate. Many issues related to irrigation's climate impact are addressed in studies that apply a wide range of models. These involve substantial uncertainties related to differences in the model's structure and its parametrizations on the one hand and the need for simplifying assumptions for the representation of irrigation on the other hand. To address these uncertainties, we used the Max Planck Institute for Meteorology's Earth System model into which a simple irrigation scheme was implemented. In order to estimate possible uncertainties with regard to the model's more general structure, we compared the climate impact of irrigation between three simulations that use different schemes for the land-surface-atmosphere coupling. Here, it can be shown that the choice of coupling scheme does not only affect the magnitude of possible impacts but even their direction. For example, when using a scheme that does not explicitly resolve spatial subgrid scale heterogeneity at the surface, irrigation reduces the atmospheric water content, even in heavily irrigated regions. Contrarily, in simulations that use a coupling scheme that resolves heterogeneity at the surface or even within the lowest layers of the atmosphere, irrigation increases the average atmospheric specific humidity. A second experiment targeted possible uncertainties related to the representation of irrigation characteristics. Here, in four simulations the irrigation effectiveness (controlled by the target soil moisture and the non-vegetated fraction of the grid box that receives irrigation) and the timing of delivery were varied. The second experiment shows that uncertainties related to the modelled irrigation characteristics, especially the irrigation effectiveness, are also substantial. In general the impact of irrigation on the state of the land surface is more than three times larger when assuming a low irrigation effectiveness than when a high effectiveness is assumed. For certain variables, such as the vertically integrated water vapour, the impact is almost an order of magnitude larger. The timing of irrigation also has non-negligible effects on the simulated climate impacts and it can strongly alter their seasonality.

The role of groundwater in hydrological processes and memory

NASA Astrophysics Data System (ADS)

Lo, Min-Hui

The interactions between soil moisture and groundwater play important roles in controlling Earth's climate, by changing the terrestrial water cycle. However, most contemporary land surface models (LSMs) used for climate modeling lack any representation of groundwater aquifers. In this dissertation, the effects of water table dynamics on the National Center for Atmospheric Research (NCAR) Community Land Model (CLM) and Community Atmosphere Model (CAM) hydrology and land-atmosphere simulations are investigated. First, a simple, lumped unconfined aquifer model is incorporated into the CLM, in which the water table is interactively coupled to the soil moisture through groundwater recharge fluxes. The recent availability of GRACE water storage data provides a unique opportunity to constrain LSMs simulations of terrestrial hydrology. A multi-objective calibration framework using GRACE and streamflow data is developed. This approach improves parameter estimation and reduces the uncertainty of water table simulations in the CLM. Next, experiments are conducted with the off-line CLM to explore the effects of groundwater on land surface memory. Results show that feedbacks of groundwater on land surface memory can be positive, negative, or neutral depending on water table dynamics. The CAM-CLM is further utilized to investigate the effects of water table dynamics on spatial-temporal variations of precipitation. Results indicate that groundwater can increase short-term (seasonal) and long-term (interannual) memory of precipitation for some regions with suitable groundwater table depth. Finally, lower tropospheric water vapor is increased due to the presence of groundwater in the model. However, the impact of groundwater on the spatial distribution of precipitation is not globally homogeneous. In the boreal summer, tropical land regions show a positive (negative) anomaly over the Northern (Southern) Hemisphere. The increased tropical precipitation follows the climatology of the convective zone rather than that of evapotranspiration. In contrast, evapotranspiration is the major contribution to the increased precipitation in the transition climatic zone (e.g., Central North America), where the land and atmosphere are strongly coupled. This dissertation reveals the highly nonlinear responses of precipitation and soil moisture to the groundwater representation in the model, and also underscores the importance of subsurface hydrological memory processes in the climate system.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of dissolved arsenic, boron, lithium, selenium, strontium, thallium, and vanadium using inductively coupled plasma-mass spectrometry

USGS Publications Warehouse

Garbarino, John R.

1999-01-01

The inductively coupled plasma?mass spectrometric (ICP?MS) methods have been expanded to include the determination of dissolved arsenic, boron, lithium, selenium, strontium, thallium, and vanadium in filtered, acidified natural water. Method detection limits for these elements are now 10 to 200 times lower than by former U.S. Geological Survey (USGS) methods, thus providing lower variability at ambient concentrations. The bias and variability of the method was determined by using results from spike recoveries, standard reference materials, and validation samples. Spike recoveries at 5 to 10 times the method detection limit and 75 micrograms per liter in reagent-water, surface-water, and groundwater matrices averaged 93 percent for seven replicates, although selected elemental recoveries in a ground-water matrix with an extremely high iron sulfate concentration were negatively biased by 30 percent. Results for standard reference materials were within 1 standard deviation of the most probable value. Statistical analysis of the results from about 60 filtered, acidified natural-water samples indicated that there was no significant difference between ICP?MS and former USGS official methods of analysis.

Global Ocean Forecast System 3.1 Validation Test

DTIC Science & Technology

2017-05-04

number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK...cycle with the Navy Coupled Ocean Data Assimilation. Additionally it uses Improved Synthetic Ocean Profiles to project surface information downward into...are retained, with the additional 9 layers all located near the surface such that at least the top 14 layers are always sigma -z levels so that water

Establishing and applying of a coupled individual based model of edible jellyfish(Rhopilema esculentum Kishinouye) releasing in the Liaodong Bay

NASA Astrophysics Data System (ADS)

Yin, Liping; Qiao, Fangli

2017-04-01

A three-dimensional circulation-surface wave coupled hydrodynamic model coupled with an individual-based jellyfish model was established to investigate the influence of physical process on edible jellyfish releasing stock enhancement in Liaodong Bay. Sensitivity experiments show that the wind intensity and direction have both direct and indirect impacts on the distribution of the jellyfish. When the wind is strong, the surface current in Liaodong Bay has the same direction of the wind. Under the co-effect of the ocean current transport and the surface wind transport, the jellyfish inhabits in the northeast of Liaodong bay, which is consistent with the observation. In the circumstance of weak wind, the circulation is clockwise and the jellyfish will spread around the 5m isobaths following the circulation. Research of the jellyfish distribution shows that the releasing jellyfish will stay in Liaodong bay in its whole life history, hence Liaodong Bay is a quite suitable area for enhancement releasing. The influence of the temperature on releasing region and date is also investigated. The threshold date during 2008 to 2016 is calculated, which is the date when the temperature of water within 10m isobaths in Liaodong Bay rises up to 15oC. In 2010, the threshold date came about one week later while the medusa releasing date remains the same in 2009. As a result, higher fatality rate of medusa caused by the cold water resulted in lower recapture rate in 2010. Therefore, the releasing date and location should be varied according to environmental conditions. The threshold date tends to appear earlier during 2008 to 2016, which suggests an earlier releasing date. In summer, due to the cold water mass intrusion from the south, the releasing date in the north area should be earlier than in the south.

Concentrations of asbestos fibers and metals in drinking water caused by natural crocidolite asbestos in the soil from a rural area.

PubMed

Wei, Binggan; Ye, Bingxiong; Yu, Jiangping; Jia, Xianjie; Zhang, Biao; Zhang, Xiuwu; Lu, Rongan; Dong, Tingrong; Yang, Linsheng

2013-04-01

Asbestos fibers and metals in drinking water are of significant importance to the field of asbestos toxicology. However, little is known about asbestos fibers and metals in drinking water caused by naturally occurring asbestos. Therefore, concentrations of asbestos fibers and metals in well and surface waters from asbestos and control areas were measured by scanning electron microscopy (SEM), inductively coupled plasma (ICP) optical emission spectrometer, and ICP-mass spectrometry in this study. The results indicated that the mean concentration of asbestos fibers was 42.34 millions of fibers per liter by SEM, which was much higher than the permission exposure level. The main compositions of both asbestos fibers in crocidolite mineral and in drinking water were Na, Mg, Fe, and Si based on energy dispersive X-ray analysis. This revealed that the drinking water has been contaminated by asbestos fibers from crocidolite mineral in soil and rock. Except for Cr, Pb, Zn, and Mn, the mean concentrations of Ni, Na, Mg, K, Fe, Ca, and SiO2 were much higher in both surface water and well waters from the asbestos area than in well water from the control area. The results of principal component and cluster analyses indicated that the metals in surface and well waters from the asbestos area were significantly influenced by crocidolite mineral in soil and rock. In the asbestos area, the mean concentrations of asbestos fibers and Ni, Na, Mg, K, Fe, Ca, and SiO2 were higher in surface and well waters, indicating that asbestos fibers and the metals were significantly influenced by crocidolite in soil and rock.

Applicability of Electrical and Electroanalytical Techniques to Detect Water and Characterize the Geochemistry of Undisturbed Planetary Soils

NASA Technical Reports Server (NTRS)

Seshadri, S.; Buehler, M. G.; Anderson, R. C.; Kuhlman, G. M.; Keymeulen, D.; Cheung, I. W.; Schaap, M. G.

2005-01-01

The search for life is a primary goal of NASA s planetary exploration program. The search is, of necessity, tiered in both the detection approach (looking for evidence of microbial fossils or the presence of water in the geological history of a planetary body and/or looking for evidence of water, energy sources, precursors to life, signatures of life and/or life itself in the present day planetary environment) and in the survey method (scale, range, specificity) employed. Terrestrial investigations suggests that life as we know it requires water. Thus, the search for extant microbial life and habitats requires identifying water-bearing soils. Determining Reduction-Oxidation (REDOX) couples present in water, once it is found, provides information on soil geochemistry and identifies potential chemical energy sources for life. Mars offers a near-term target for conducting this search. The identification of gully formation [1], layered deposits [2] and elemental ratios of bromine and chlorine [3] present indirect evidence that water was abundant locally in the Martian past. Additionally, Viking images of polar ice and frost formation on the surface of Mars demonstrate that water can exist in at least some near-surface regions of present-day Mars. Atmospheric pressure data further suggest that liquid water may be stable for short periods of time in the mid-latitudes of the Martian surface. [4] Measurements of the global distribution of hydrogen in the Martian regolith offer tantalizing indirect evidence that water may at least exist in near-surface soils. [5] Evidently, any water to be found is likely to exist as soil mixtures at levels ranging between approx.0.5% and approx.5 %.

Estimating the Mediterranean Sea Water Budget: impact of RCM design

NASA Astrophysics Data System (ADS)

Somot, S.; Elguindi, N.; Sanchez-Gomez, E.; Herrmann, M.; Déqué, M.

2009-09-01

The Mediterranean Sea can be considered as a thermodynamic machine that exchanges water and heat with the Atlantic Ocean through the Strait of Gibraltar and with the atmosphere through its surface. Considering the Mediterranean Sea Water Budget (MSWB) multi-year mean, the Mediterranean basin looses water at the surface due to an excess of evaporation over freshwater input (precipitation, river runoff, Black Sea input). Moreover the MSWB largely drives the Mediterranean Sea water mass formation and therefore a large part of its thermohaline circulation. This could even have an impact on the characteristics of the Atlantic thermohaline circulation through the Mediterranean Outflow Waters that flow into the Atlantic at a depth of about 1000 m. From a climate point of view, the MSWB acts as a water source for the Mediterranean countries and therefore plays an important role on the water resources of the region. The regional physical characteristics of the Mediterranean basin (complex orography, strong land-sea contrast, land-atmosphere coupling, air-sea coupling, river inflow, Gibraltar Strait constraint and complex ocean bathymetry) strongly influence the various components of the MSWB. Moreover extreme precipitation events over land and strong evaporation events over the sea due to local winds can play a non-negligible role on the mean MSWB despite their small spatial and temporal scales. Therefore, modelling the mean behaviour, the interannual variability and the trends of the MSWB is a challenging task of the Regional Climate Model community in the context of climate change. It is actually one of the highlighted issues of the HyMex project planned for the 2010-2020 period. We propose here to start investigating some key scientific issues of the regional modelling of the Mediterranean Sea Water Budget using a wide range of regional climate simulations performed at Météo-France or in the framework of FP6 European projects (ENSEMBLES, CIRCE). The addressed scientific questions deal with the RCM design for the following points: Q1. the horizontal resolution Q2. the physics of the RCM Q3. the regional modelling technique (stretched-grid model, limited area model, spectral nudging technique) Q4. the regional air-sea-river coupling Q5. the RCM internal variability Up-to-date observation estimates of the various terms of the MSWB are used to sort out between the different configurations of the RCMs.

ADHydro: A Large-scale High Resolution Multi-Physics Distributed Water Resources Model for Water Resource Simulations in a Parallel Computing Environment

NASA Astrophysics Data System (ADS)

lai, W.; Steinke, R. C.; Ogden, F. L.

2013-12-01

Physics-based watershed models are useful tools for hydrologic studies, water resources management and economic analyses in the contexts of climate, land-use, and water-use changes. This poster presents development of a physics-based, high-resolution, distributed water resources model suitable for simulating large watersheds in a massively parallel computing environment. Developing this model is one of the objectives of the NSF EPSCoR RII Track II CI-WATER project, which is joint between Wyoming and Utah. The model, which we call ADHydro, is aimed at simulating important processes in the Rocky Mountain west, includes: rainfall and infiltration, snowfall and snowmelt in complex terrain, vegetation and evapotranspiration, soil heat flux and freezing, overland flow, channel flow, groundwater flow and water management. The ADHydro model uses the explicit finite volume method to solve PDEs for 2D overland flow, 2D saturated groundwater flow coupled to 1D channel flow. The model has a quasi-3D formulation that couples 2D overland flow and 2D saturated groundwater flow using the 1D Talbot-Ogden finite water-content infiltration and redistribution model. This eliminates difficulties in solving the highly nonlinear 3D Richards equation, while the finite volume Talbot-Ogden infiltration solution is computationally efficient, guaranteed to conserve mass, and allows simulation of the effect of near-surface groundwater tables on runoff generation. The process-level components of the model are being individually tested and validated. The model as a whole will be tested on the Green River basin in Wyoming and ultimately applied to the entire Upper Colorado River basin. ADHydro development has necessitated development of tools for large-scale watershed modeling, including open-source workflow steps to extract hydromorphological information from GIS data, integrate hydrometeorological and water management forcing input, and post-processing and visualization of large output data sets. The ADHydro model will be coupled with relevant components of the NOAH-MP land surface scheme and the WRF mesoscale meteorological model. Model objectives include well documented Application Programming Interfaces (APIs) to facilitate modifications and additions by others. We will release the model as open-source in 2014 and begin establishing a users' community.

Particulate-free porous silicon networks for efficient capacitive deionization water desalination

PubMed Central

Metke, Thomas; Westover, Andrew S.; Carter, Rachel; Oakes, Landon; Douglas, Anna; Pint, Cary L.

2016-01-01

Energy efficient water desalination processes employing low-cost and earth-abundant materials is a critical step to sustainably manage future human needs for clean water resources. Here we demonstrate that porous silicon – a material harnessing earth abundance, cost, and environmental/biological compatibility is a candidate material for water desalination. With appropriate surface passivation of the porous silicon material to prevent surface corrosion in aqueous environments, we show that porous silicon templates can enable salt removal in capacitive deionization (CDI) ranging from 0.36% by mass at the onset from fresh to brackish water (10 mM, or 0.06% salinity) to 0.52% in ocean water salt concentrations (500 mM, or ~0.3% salinity). This is on par with reports of most carbon nanomaterial based CDI systems based on particulate electrodes and covers the full salinity range required of a CDI system with a total ocean-to-fresh water required energy input of ~1.45 Wh/L. The use of porous silicon for CDI enables new routes to directly couple water desalination technology with microfluidic systems and photovoltaics that natively use silicon materials, while mitigating adverse effects of water contamination occurring from nanoparticulate-based CDI electrodes. PMID:27101809

Particulate-free porous silicon networks for efficient capacitive deionization water desalination.

PubMed

Metke, Thomas; Westover, Andrew S; Carter, Rachel; Oakes, Landon; Douglas, Anna; Pint, Cary L

2016-04-22

Energy efficient water desalination processes employing low-cost and earth-abundant materials is a critical step to sustainably manage future human needs for clean water resources. Here we demonstrate that porous silicon - a material harnessing earth abundance, cost, and environmental/biological compatibility is a candidate material for water desalination. With appropriate surface passivation of the porous silicon material to prevent surface corrosion in aqueous environments, we show that porous silicon templates can enable salt removal in capacitive deionization (CDI) ranging from 0.36% by mass at the onset from fresh to brackish water (10 mM, or 0.06% salinity) to 0.52% in ocean water salt concentrations (500 mM, or ~0.3% salinity). This is on par with reports of most carbon nanomaterial based CDI systems based on particulate electrodes and covers the full salinity range required of a CDI system with a total ocean-to-fresh water required energy input of ~1.45 Wh/L. The use of porous silicon for CDI enables new routes to directly couple water desalination technology with microfluidic systems and photovoltaics that natively use silicon materials, while mitigating adverse effects of water contamination occurring from nanoparticulate-based CDI electrodes.

Sum-frequency generation analyses of the structure of water at amphoteric SAM-liquid water interfaces.

PubMed

Nomura, Kouji; Nakaji-Hirabayashi, Tadashi; Gemmei-Ide, Makoto; Kitano, Hiromi; Noguchi, Hidenori; Uosaki, Kohei

2014-09-01

Surfaces of both a cover glass and the flat plane of a semi-cylindrical quartz prism were modified with a mixture of positively and negatively charged silane coupling reagents (3-aminopropyltriethoxysilane (APTES) and 3-(trihydroxysilyl)propylmethylphosphonate (THPMP), respectively). The glass surface modified with a self-assembled monolayer (SAM) prepared at a mixing ratio of APTES:THPMP=4:6 was electrically almost neutral and was resistant to non-specific adsorption of proteins, whereas fibroblasts gradually adhered to an amphoteric (mixed) SAM surface probably due to its stiffness, though the number of adhered cells was relatively small. Sum frequency generation (SFG) spectra indicated that total intensity of the OH stretching region (3000-3600cm(-1)) for the amphoteric SAM-modified quartz immersed in liquid water was smaller than those for the positively and negatively charged SAM-modified quartz prisms and a bare quartz prism in contact with liquid water. These results suggested that water molecules at the interface of water and an amphoteric SAM-modified quartz prism are not strongly oriented in comparison with those at the interface of a lopsidedly charged SAM-modified quartz prism and bare quartz. The importance of charge neutralization for the anti-biofouling properties of solid materials was strongly suggested. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of a human-specific B. thetaiotaomicron IMS ...

EPA Pesticide Factsheets

Immunomagnetic separation/adenosine triphosphate (IMS/ATP) assays utilize paramagnetic beads and target-specific antibodies to isolate target organisms. Following isolation, adenosine tri-phosphate (ATP) is extracted from the target population and quantified. An inversely-coupled (Inv-IMS/ATP)assay for detection of Bacteroides thetaiotaomicron was developed and applied for rapid detection of human-associated fecal contamination in surface waters in Baja California. Specificity of the assay was tested against challenge solutions of varying concentrations of dog, gull, horse and chicken feces, and a field validation survey of coastal and WWTP effluent water quality in Rosarito and Enseneda, Baja California was conducted. Inv IMS/ATP measurements made shown to be specific and sensitive to human fecal contamination. At test concentrations of less than 1000 MPN ENT/100 mL, sensitivity and specificity of the assay both exceeded 80%. Moreover, the Inv-IMS/ATP assay yielded measurements of viable B. thetaiotaomicron that were comparable to the HF183 human marker in complex surface waters impacted with both wastewater and runoff, and the Inv-IMS/ATP assay was able to effectively differentiate between surface waters impacted with adequately and inadequately treated wastewater. The Inv-IMS/ATP assays shows promise for rapid evaluation of recreational water quality in areas where access to more expensive methods is limited and in areas where water quality in unpredicta

Modeling falling groundwater tables in major cities of the world

NASA Astrophysics Data System (ADS)

Sutanudjaja, E.; Erkens, G.

2015-12-01

Groundwater use and its over-consumption are one of the major drivers in the hydrology of many major cities in the world, particularly in delta regions. Yet, a global assessment to identify cities with declining groundwater table problems has not been done yet. In this study we used the global hydrological model PCR-GLOBWB (10 km resolution, for 1960-2010). Using this model, we globally calculated groundwater recharge and river discharge/surface water levels, as well as global water demand and abstraction from ground- and surface water resources. The output of PCR-GLOBWB model was then used to force a groundwater MODFLOW-based model simulating spatio-temporal groundwater head dynamics, including groundwater head declines in all major cities - mainly in delta regions - due to escalation in abstraction of groundwater to meet increasing water demand. Using these coupled models, we managed to identify a number of critical cities having groundwater table falling rates above 50 cm/year (average in 2000-2010), such as Barcelona, Houston, Los Angeles, Mexico City, New York, Rome and many large cities in China, Libya, India and Pakistan, as well as in Middle East and Central Asia regions. However, our simulation results overestimate the depletion rates in San Jose, Tokyo, Venice, and other cities where groundwater usages have been aggressively managed and replaced by importing surface water from other places. Moreover, our simulation might underestimate the declining groundwater head trends in some familiar cases, such as Bangkok (12 cm/year), Ho Chi Minh City (34 cm/year), and Jakarta (26 cm/year). The underestimation was due to an over-optimistic model assumption in allocating surface water for satisfying urban water needs. In reality, many big cities, although they are located in wet regions and have abundant surface water availability, still strongly rely on groundwater sources due to inadequate facilities to treat and distribute surface water resources.

Modeling falling groundwater tables in major cities of the world

NASA Astrophysics Data System (ADS)

Sutanudjaja, Edwin; Erkens, Gilles

2016-04-01

Groundwater use and its over-consumption are one of the major drivers in the hydrology of many major cities in the world, particularly in delta regions. Yet, a global assessment to identify cities with declining groundwater table problems has not been done yet. In this study we used the global hydrological model PCR-GLOBWB (10 km resolution, for 1960-2010). Using this model, we globally calculated groundwater recharge and river discharge/surface water levels, as well as global water demand and abstraction from ground- and surface water resources. The output of PCR-GLOBWB model was then used to force a groundwater MODFLOW-based model simulating spatio-temporal groundwater head dynamics, including groundwater head declines in all major cities - mainly in delta regions - due to escalation in abstraction of groundwater to meet increasing water demand. Using these coupled models, we managed to identify a number of critical cities having groundwater table falling rates above 50 cm/year (average in 2000-2010), such as Barcelona, Houston, Los Angeles, Mexico City, New York, Rome and many large cities in China, Libya, India and Pakistan, as well as in Middle East and Central Asia regions. However, our simulation results overestimate the depletion rates in San Jose, Tokyo, Venice, and other cities where groundwater usages have been aggressively managed and replaced by importing surface water from other places. Moreover, our simulation might underestimate the declining groundwater head trends in some familiar cases, such as Bangkok (12 cm/year), Ho Chi Minh City (34 cm/year), and Jakarta (26 cm/year). The underestimation was due to an over-optimistic model assumption in allocating surface water for satisfying urban water needs. In reality, many big cities, although they are located in wet regions and have abundant surface water availability, still strongly rely on groundwater sources due to inadequate facilities to treat and distribute surface water resources.

The covariability of North American land-atmosphere coupling strength and rainfall characteristics in reanalyses

NASA Astrophysics Data System (ADS)

Ferguson, C. R.; Roundy, J. K.; Kim, W.

2016-12-01

The GEWEX North American Regional Hydroclimate Project (RHP): Water for the Food Baskets of the World initiative is aimed at: improving understanding of key processes—both natural and anthropogenic—that determine water availability, improving understanding of the independent and collective sensitivity of these processes to local and global change, and the integration of knowledge gained into the next model development cycle for the benefit of improved water availability forecasts. Considering that the agricultural sector accounts for three quarters of water withdrawals and suffers the brunt of drought-related financial damages, a rational RHP focal point is subseasonal-to-seasonal forecast skill. Forecasts on this timescale over the Great Plains food basket have shown particular sensitivity to land initial conditions (i.e., soil moisture, snow cover, and vegetative stress) and the realism of modeled land-atmosphere (L-A) coupling. L-A coupling strength denotes the degree to which the model's land scheme (i.e., soil column memory and surface flux partitioning) affect the atmospheric forecast scheme's daytime evolution of the convective boundary layer, including cloud development and precipitation. Prior studies have connected L-A coupling strength to the phase and amplitude of the diurnal precipitation cycle, as well as the evolution of heatwaves and drought. In this study, we apply three metrics of L-A coupling strength: soil moisture memory, the two-legged coupling metric, and the convective triggering potential-humidity index, to the 161-year NOAA-Cooperative Institute for Research in Environmental Sciences Twentieth Century Reanalysis (20CRV2c). Over the full period, we also analyze warm-season rainfall characteristics and subsequently perform statistical trend and change point analyses on both sets of results. We test the stationarity of both coupling and rainfall characteristics as well as the hypothesis that any detected shifts in coupling strength and afternoon rainfall frequency will coincide. Although the source data has inherent limitations that will be quantified and discussed, the results will be the first of their kind over such a long period of record and will provide key insights for the North American RHP.

Salvinia-Effect-Inspired "Sticky" Superhydrophobic Surfaces by Meniscus-Confined Electrodeposition.

PubMed

Zheng, Deyin; Jiang, Youhua; Yu, Wentao; Jiang, Xiufen; Zhao, Xin; Choi, Chang-Hwan; Sun, Guangyi

2017-11-28

Inspired by the Salvinia effect, we report the fabrication and characterization of a novel "sticky" superhydrophobic surface sustaining a Cassie-Baxter wetting state for water droplets with high contact angles but strong solid-liquid retention. Unlike superhydrophobic surfaces mimicking the lotus or petal effect, whose hydrophobicity and droplet retention are typically regulated by hierarchical micro- and nanostructures made of a homogeneous material with the same surface energy, our superhydrophobic surface merely requires singular microstructures covered with a hydrophobic coating but creatively coupled with hydrophilic tips with different surface energy. Hydrophilic tips are selectively formed by meniscus-confined electrodeposition of a metal (e.g., nickel) layer on top of hydrophobic microstructures. During the electrodeposition process, the superhydrophobic surface retains its plastron so that the electrolyte cannot penetrate into the cavity of hydrophobic microstructures, consequently making the electrochemical reaction between solid and electrolyte occur only on the tip. In contrast to typical superhydrophobic surfaces where droplets are highly mobile, the "sticky" superhydrophobic surface allows a water droplet to have strong local pinning and solid-liquid retention on the hydrophilic tips, which is of great significance in many droplet behaviors such as evaporation.

MCX based solid phase extraction combined with liquid chromatography tandem mass spectrometry for the simultaneous determination of 31 endocrine-disrupting compounds in surface water of Shanghai.

PubMed

Zhang, Hong-Chang; Yu, Xue-jun; Yang, Wen-chao; Peng, Jin-feng; Xu, Ting; Yin, Da-Qiang; Hu, Xia-lin

2011-10-15

A novel analytical method employing MCX (mixed-mode cationic exchange) based solid phase extraction (SPE) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed to detect 31 endocrine-disrupting compounds (EDCs) in surface water samples simultaneously. The target EDCs belong to five classes, including seven estrogens, eight androgens, six progesterones, five adrenocortical hormones and five industrial compounds. In order to simultaneously concentrate the target EDCs and eliminate matrix interferences in the water samples, MCX SPE cartridges were employed for SPE, and then followed by a simple and highly efficient three-step sequential elution procedure. Two electrospray ionization (ESI) detection modes, positive (ESI+) and (ESI-), were optimized for HPLC-MS/MS analysis to obtain the highest sensitivity for all the EDCs. The limits of detection (LODs) were 0.02-1.9 ng L(-1), which are lower than or comparable to these reported in references. Wide linear ranges (LOD-100 ng L(-1) for ESI+ mode, and LOD-200 ng L(-1) for ESI- mode) were obtained with determination coefficients (R(2)) higher than 0.99 for all the compounds. With five internal standards, good recoveries (84.4-103.0%) of all the target compounds were obtained in selected surface water samples. The developed method was successfully applied to investigate the EDCs occurrence in the surface water of Shanghai by analyzing surface water samples from 11 sites. The results showed that nearly all the target compounds (30 in 31) were present in the surface water samples of Shanghai, of which three industrial compounds (4-t-OP, BPA, and BPF) showed the highest concentrations (median concentrations were 11.88-23.50 ng L(-1)), suggesting that industrial compounds were the dominating EDCs in the surface water of Shanghai, and much more attention should be paid on these compounds. Our present research demonstrated that SPE with MCX cartridges combined with HPLC-MS/MS was convenient, efficient and reliable for multiclass analysis of EDCs in surface water. Copyright © 2011 Elsevier B.V. All rights reserved.

Estimation of Leakage Potential of Selected Sites in Interstate and Tri-State Canals Using Geostatistical Analysis of Selected Capacitively Coupled Resistivity Profiles, Western Nebraska, 2004

USGS Publications Warehouse

Vrabel, Joseph; Teeple, Andrew; Kress, Wade H.

2009-01-01

With increasing demands for reliable water supplies and availability estimates, groundwater flow models often are developed to enhance understanding of surface-water and groundwater systems. Specific hydraulic variables must be known or calibrated for the groundwater-flow model to accurately simulate current or future conditions. Surface geophysical surveys, along with selected test-hole information, can provide an integrated framework for quantifying hydrogeologic conditions within a defined area. In 2004, the U.S. Geological Survey, in cooperation with the North Platte Natural Resources District, performed a surface geophysical survey using a capacitively coupled resistivity technique to map the lithology within the top 8 meters of the near-surface for 110 kilometers of the Interstate and Tri-State Canals in western Nebraska and eastern Wyoming. Assuming that leakage between the surface-water and groundwater systems is affected primarily by the sediment directly underlying the canal bed, leakage potential was estimated from the simple vertical mean of inverse-model resistivity values for depth levels with geometrically increasing layer thickness with depth which resulted in mean-resistivity values biased towards the surface. This method generally produced reliable results, but an improved analysis method was needed to account for situations where confining units, composed of less permeable material, underlie units with greater permeability. In this report, prepared by the U.S. Geological Survey in cooperation with the North Platte Natural Resources District, the authors use geostatistical analysis to develop the minimum-unadjusted method to compute a relative leakage potential based on the minimum resistivity value in a vertical column of the resistivity model. The minimum-unadjusted method considers the effects of homogeneous confining units. The minimum-adjusted method also is developed to incorporate the effect of local lithologic heterogeneity on water transmission. Seven sites with differing geologic contexts were selected following review of the capacitively coupled resistivity data collected in 2004. A reevaluation of these sites using the mean, minimum-unadjusted, and minimum-adjusted methods was performed to compare the different approaches for estimating leakage potential. Five of the seven sites contained underlying confining units, for which the minimum-unadjusted and minimum-adjusted methods accounted for the confining-unit effect. Estimates of overall leakage potential were lower for the minimum-unadjusted and minimum-adjusted methods than those estimated by the mean method. For most sites, the local heterogeneity adjustment procedure of the minimum-adjusted method resulted in slightly larger overall leakage-potential estimates. In contrast to the mean method, the two minimum-based methods allowed the least permeable areas to control the overall vertical permeability of the subsurface. The minimum-adjusted method refined leakage-potential estimation by additionally including local lithologic heterogeneity effects.

Study of the effect of wind speed on evaporation from soil through integrated modeling of atmospheric boundary layer and shallow subsurface

NASA Astrophysics Data System (ADS)

Davarzani, Hossein; Smits, Kathleen; Tolene, Ryan; Illangasekare, Tissa

2013-04-01

The study of the interaction between the land and atmosphere is paramount to our understanding of many emerging problems to include climate change, the movement of green house gases such as possible leaking of sequestered CO2 and the accurate detection of buried objects such as landmines. Soil moisture distribution in the shallow subsurface becomes a critical factor in all these problems. The heat and mass flux in the form of soil evaporation across the land surface couples the atmospheric boundary layer to the shallow subsurface. The coupling between land and the atmosphere leads to highly dynamic interactions between the porous media properties, transport processes and boundary conditions, resulting in dynamic evaporative behavior. However, the coupling at the land-atmospheric interface is rarely considered in most current models and their validation for practical applications. This is due to the complexity of the problem in field scenarios and the scarcity of field or laboratory data capable of testing and refining coupled energy and mass transfer theories. In most efforts to compute evaporation from soil, only indirect coupling is provided to characterize the interaction between non-isothermal multiphase flows under realistic atmospheric conditions even though heat and mass flux are controlled by the coupled dynamics of the land and the atmospheric boundary layer. In earlier drying modeling concepts, imposing evaporation flux (kinetic of relative humidity) and temperature as surface boundary condition is often needed. With the goal of improving our understanding of the land/atmospheric coupling, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model consists of the coupled equations of mass conservation for the liquid phase (water) and gas phase (water vapor and air) in porous medium with gas phase (water vapor and air) in free flow domain under non-isothermal, non-equilibrium conditions. The boundary conditions at the porous medium-free flow medium interface include dynamical, thermal and solutal equilibriums, and using the Beavers-Joseph slip boundary condition. What is unique about this model is that the evaporation rate and soil surface temperature conditions come directly from the model output. In order to experimentally validate the numerical results, we developed and used a unique two dimensional wind tunnel placed above a soil tank equipped with a network of different sensors. A series of experiments under varying boundary conditions, using a test sand for which the hydraulic and thermal properties were well characterized, were performed. Precision data for soil moisture, soil and air temperature and relative humidity, and also wind velocity under well-controlled transient heat and wind boundary conditions was generated. Results from numerical simulations were compared with experimental data. Results demonstrate that the coupling concept can predict the different stages of the drying process in porous media with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time at low velocity values; then, at high values of wind speed the evaporation rate becomes less dependent of flow in free fluid. In the opposite, the impact of the wind speed on the second stage evaporation (diffusion dominant stage) is not significant. The proposed theoretical model can be used to predict the evaporation process where a porous medium flow is coupled to a free flow for different practical applications.

An agricultural drought index to incorporate the irrigation process and reservoir operations: A case study in the Tarim River Basin

NASA Astrophysics Data System (ADS)

Li, Zehua; Hao, Zhenchun; Shi, Xiaogang; Déry, Stephen J.; Li, Jieyou; Chen, Sichun; Li, Yongkun

2016-08-01

To help the decision making process and reduce climate change impacts, hydrologically-based drought indices have been used to determine drought severity in the Tarim River Basin (TRB) over the past decades. As the major components of the surface water balance, however, the irrigation process and reservoir operations have not been incorporated into drought indices in previous studies. Therefore, efforts are needed to develop a new agricultural drought index, which is based on the Variable Infiltration Capacity (VIC) model coupled with an irrigation scheme and a reservoir module. The new drought index was derived from the simulated soil moisture data from a retrospective VIC simulation from 1961 to 2007 over the irrigated area in the TRB. The physical processes in the coupled VIC model allow the new agricultural drought index to take into account a wide range of hydrologic processes including the irrigation process and reservoir operations. Notably, the irrigation process was found to dominate the surface water balance and drought evolution in the TRB. Furthermore, the drought conditions identified by the new agricultural drought index presented a good agreement with the historical drought events that occurred in 1993-94, 2004, and 2006-07, respectively. Moreover, the spatial distribution of coupled VIC model outputs using the new drought index provided detailed information about where and to what extent droughts occurred.

Integrated Water Flow Model (IWFM), A Tool For Numerically Simulating Linked Groundwater, Surface Water And Land-Surface Hydrologic Processes

NASA Astrophysics Data System (ADS)

Dogrul, E. C.; Brush, C. F.; Kadir, T. N.

2006-12-01

The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D land surface, lake, stream flow and vertical unsaturated-zone flow processes which are solved simultaneously at each time step. The groundwater flow system is simulated as a multilayer aquifer system with a mixture of confined and unconfined aquifers separated by semiconfining layers. The groundwater flow process can simulate changing aquifer conditions (confined to unconfined and vice versa), subsidence, tile drains, injection wells and pumping wells. The land surface process calculates elemental water budgets for agricultural, urban, riparian and native vegetation classes. Crop water demands are dynamically calculated using distributed soil properties, land use and crop data, and precipitation and evapotranspiration rates. The crop mix can also be automatically modified as a function of pumping lift using logit functions. Surface water diversions and groundwater pumping can each be specified, or can be automatically adjusted at run time to balance water supply with water demand. The land-surface process also routes runoff to streams and deep percolation to the unsaturated zone. Surface water networks are specified as a series of stream nodes (coincident with groundwater nodes) with specified bed elevation, conductance and stage-flow relationships. Stream nodes are linked to form stream reaches. Stream inflows at the model boundary, surface water diversion locations, and one or more surface water deliveries per location are specified. IWFM routes stream flows through the network, calculating groundwater-surface water interactions, accumulating inflows from runoff, and allocating available stream flows to meet specified or calculated deliveries. IWFM utilizes a very straight-forward input file structure, allowing rapid development of complex simulations. A key feature of IWFM is a new algorithm for computation of groundwater flow across element faces. Enhancements to version 3.0 include automatic time-tracking of input and output data sets, linkage with the HEC-DSS database, and dynamic crop allocation using logit functions. Utilities linking IWFM to the PEST automated calibration suite are also available. All source code, executables and documentation are available for download from the DWR web site. IWFM is currently being used to develop hydrologic simulations of California's Central Valley (C2VSIM); the west side of California's San Joaquin Valley (WESTSIM); Butte County, CA; Solano County, CA; Merced County, CA; and the Oregon side of the Walla Walla River Basin.

Pharmaceutical Occurrence in Groundwater and Surface Waters in Forests Land-Applied with Municipal Wastewater

PubMed Central

McEachran, Andrew D.; Shea, Damian; Bodnar, Wanda; Nichols, Elizabeth Guthrie

2016-01-01

The occurrence and fate of pharmaceutical and personal care products in the environment are of increasing public importance because of their ubiquitous nature and documented effects on wildlife, ecosystems, and potentially humans. One potential, yet undefined, source of entry of pharmaceuticals into the environment is via the land application of municipal wastewater onto permitted lands. The objective of the present study is to determine the extent to which pharmaceuticals are mitigated by or exported from managed tree plantations irrigated with municipal wastewater. A specific focus of the present study is the presence of pharmaceutical compounds in groundwater and surface water discharge. The study site is a municipality that land-applies secondary treated wastewater onto 930 hectares of a 2000-hectare managed hardwood and pine plantation. A suite of 33 pharmaceuticals and steroid hormones was targeted in the analysis, which consisted of monthly grab sampling of groundwater, surface water, and wastewater, followed by concentration and cleanup via solid phase extraction and separation, detection, and quantification via liquid chromatography coupled with tandem mass spectrometry. More than one-half of all compounds detected in irrigated wastewater were not present in groundwater and subsequent surface water. However, antibiotics, nonsteroidal anti-inflammatory drugs, caffeine, and other prescription and over-the-counter drugs remained in groundwater and were transported into surface water at concentrations up to 10 ng/L. These results provide important documentation for pharmaceutical fate and transport in forest systems irrigated with municipal wastewater, a previously undocumented source of environmental entry. PMID:26297815

Using SWAT-MODFLOW to simulate groundwater flow and groundwater-surface water interactions in an intensively irrigated stream-aquifer system

NASA Astrophysics Data System (ADS)

Wei, X.; Bailey, R. T.

2017-12-01

Agricultural irrigated watersheds in semi-arid regions face challenges such as waterlogging, high soil salinity, reduced crop yield, and leaching of chemical species due to extreme shallow water tables resulting from long-term intensive irrigation. Hydrologic models can be used to evaluate the impact of land management practices on water yields and groundwater-surface water interactions in such regions. In this study, the newly developed SWAT-MODFLOW, a coupled surface/subsurface hydrologic model, is applied to a 950 km2 watershed in the Lower Arkansas River Valley (southeastern Colorado). The model accounts for the influence of canal diversions, irrigation applications, groundwater pumping, and earth canal seepage losses. The model provides a detailed description of surface and subsurface flow processes, thereby enabling detailed description of watershed processes such as runoff, infiltration, in-streamflow, three-dimensional groundwater flow in a heterogeneous aquifer system with sources and sinks (e.g. pumping, seepage to subsurface drains), and spatially-variable surface and groundwater exchange. The model was calibrated and tested against stream discharge from 5 stream gauges in the Arkansas River and its tributaries, groundwater levels from 70 observation wells, and evapotranspiration (ET) data estimated from satellite (ReSET) data during the 1999 to 2007 period. Since the water-use patterns within the study area are typical of many other irrigated river valleys in the United States and elsewhere, this modeling approach is transferable to other regions.

Analysis of Water Vapour Flux Between Alpine Wetlands Underlying the Surface and Atmosphere in the Source Region of the Yellow River

NASA Astrophysics Data System (ADS)

Xie, Y.; Wen, J.; Liu, R.; Wang, X.; JIA, D.

2017-12-01

Wetland underlying surface is sensitive to climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Previous studies, which focused on the forest, grassland and farmland ecosystems, lack research on the alpine wetlands. In addition, research on the environmental control mechanism of latent heat flux is still qualitative and lacks quantitative evaluations and calculations. Using data from the observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors (solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows: Due to the diurnal variations of solar radiation and wind speed, the diurnal variations of the Ω factor present a trend in which the Ω factor are small in the morning and large in the evening. Due to the vegetation growing cycle, the seasonal variations of the Ω factor present a reverse "U" trend . These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over the latent heat flux. This conforms to omega theory. The values for average absolute atmospheric factor (surface factor or total ) control exercised by solar radiation and water vapour pressure are 0.20 (0.02 or 0.22 ) and 0.005 (-0.07 or -0.06) W·m-2·Pa-1, respectively.. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on the latent heat flux. The average Ω factor is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between the alpine wetland surface and the atmosphere system is low. The actual measurements agree with omega theory. The latent heat flux is mainly influenced by solar radiation. From the above, our study has provided reference information for exploring the influences of environmental factors on the latent heat flux over the alpine wetlands of the Yellow River source region.

Using WEED to simulate the global wetland distribution in a ESM

NASA Astrophysics Data System (ADS)

Stacke, Tobias; Hagemann, Stefan

2016-04-01

Lakes and wetlands are an important land surface feature. In terms of hydrology, they regulate river discharge, mitigate flood events and constitute a significant surface water storage. Considering physical processes, they link the surface water and energy balances by altering the separation of incoming energy into sensible and latent heat fluxes. Finally, they impact biogeochemical processes and may act as carbon sinks or sources. Most global hydrology and climate models regard wetland extent and properties as constant in time. However, to study interactions between wetlands and different states of climate, it is necessary to implement surface water bodies (thereafter referred to as wetlands) with dynamical behavior into these models. Besides an improved representation of geophysical feedbacks between wetlands, land surface and atmosphere, a dynamical wetland scheme could also provide estimates of soil wetness as input for biogeochemical models, which are used to compute methane production in wetlands. Recently, a model for the representation of wetland extent dynamics (WEED) was developed as part of the hydrology model (MPI-HM) of the Max-Planck-Institute for Meteorology (MPI-M). The WEED scheme computes wetland extent in agreement with the range of observations for the high northern latitudes. It simulates a realistic seasonal cycle which shows sensitivity to northern snow-melt as well as rainy seasons in the tropics. Furthermore, flood peaks in river discharge are mitigated. However, the WEED scheme overestimates wetland extent in the Tropics which might be related to the MPI-HM's simplified potential evapotranspiration computation. In order to overcome this limitation, the WEED scheme is implemented into the MPI-M's land surface model JSBACH. Thus, not only its effect on water fluxes can be investigated but also its impact on the energy cycle, which is not included in the MPI-HM. Furthermore, it will be possible to analyze the physical effects of wetlands in a coupled land-atmosphere simulation. First simulations with JSBACH-WEED show results similar to the MPI-HM simulations. As the next step, the scheme is modified to account for energy cycle relevant issues such as the dynamical alteration of surface albedo as well as the allocation of appropriate thermal properties to the wetlands. In our presentation, we will give an overview on the functionality of the WEED scheme and the effect of wetlands in coupled land-atmosphere simulations.

Understanding groundwater, surface water, and hyporheic zone biogeochemical processes in a Chalk catchment using fluorescence properties of dissolved and colloidal organic matter

NASA Astrophysics Data System (ADS)

Lapworth, D. J.; Gooddy, D. C.; Allen, D.; Old, G. H.

2009-09-01

Understanding groundwater-surface water (GW-SW) interaction in Chalk catchments is complicated by the degree of geological heterogeneity. At this study site, in southern United Kingdom, alluvial deposits in the riparian zone can be considered as a patchwork of varying grades and types with an equally varied lateral connectivity. Some display good connection with the river system and others good connection with the groundwater system and, by definition, poorer connectivity with the surface water. By coupling tangential flow fractionation (TFF) with fluorescence analysis we were able to characterize the organic matter in the river and hyporheic zone. There is a significant proportion of particulate and colloidal fluorescent organic matter (FOM) within the river system and at depth within the gravels beneath the river channel. At depth in the hyporheic zone, the surface water inputs are dampened by mixing with deeper groundwater FOM. The shallow (0-0.5 m below river bed) hyporheic zone is highly dynamic as a result of changing surface water inputs from upstream processes. Labile C in the form of protein-like FOM appears to be attenuated preferentially compared to fulvic-like fluorescence in the hyporheic zone compared to the adjacent gravel and sand deposits. These preliminary findings have important implications for understanding nutrient and trace element mobility and attenuation within the groundwater, surface water, and hyporheic zone of permeable Chalk catchments. Fluorescence analysis of dissolved organic matter has been shown to be a useful environmental tracer that can be used in conjunction with other methods to understand GW-SW processes within a permeable Chalk catchment.

Towards an Improved Represenation of Reservoirs and Water Management in a Land Surface-Hydrology Model

NASA Astrophysics Data System (ADS)

Yassin, F.; Anis, M. R.; Razavi, S.; Wheater, H. S.

2017-12-01

Water management through reservoirs, diversions, and irrigation have significantly changed river flow regimes and basin-wide energy and water balance cycles. Failure to represent these effects limits the performance of land surface-hydrology models not only for streamflow prediction but also for the estimation of soil moisture, evapotranspiration, and feedbacks to the atmosphere. Despite recent research to improve the representation of water management in land surface models, there remains a need to develop improved modeling approaches that work in complex and highly regulated basins such as the 406,000 km2 Saskatchewan River Basin (SaskRB). A particular challenge for regional and global application is a lack of local information on reservoir operational management. To this end, we implemented a reservoir operation, water abstraction, and irrigation algorithm in the MESH land surface-hydrology model and tested it over the SaskRB. MESH is Environment Canada's Land Surface-hydrology modeling system that couples Canadian Land Surface Scheme (CLASS) with hydrological routing model. The implemented reservoir algorithm uses an inflow-outflow relationship that accounts for the physical characteristics of reservoirs (e.g., storage-area-elevation relationships) and includes simplified operational characteristics based on local information (e.g., monthly target volume and release under limited, normal, and flood storage zone). The irrigation algorithm uses the difference between actual and potential evapotranspiration to estimate irrigation water demand. This irrigation demand is supplied from the neighboring reservoirs/diversion in the river system. We calibrated the model enabled with the new reservoir and irrigation modules in a multi-objective optimization setting. Results showed that the reservoir and irrigation modules significantly improved the MESH model performance in generating streamflow and evapotranspiration across the SaskRB and that this our approach provides a basis for improved large scale hydrological modelling.

Interfacial Mechanisms of Water Vapor Sorption into Cellulose Nanofibril Films as Revealed by Quantitative Models.

PubMed

Hakalahti, Minna; Faustini, Marco; Boissière, Cédric; Kontturi, Eero; Tammelin, Tekla

2017-09-11

Humidity is an efficient instrument for facilitating changes in local architectures of two-dimensional surfaces assembled from nanoscaled biomaterials. Here, complementary surface-sensitive methods are used to collect explicit and precise experimental evidence on the water vapor sorption into (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidized cellulose nanofibril (CNF) thin film over the relative humidity (RH) range from 0 to 97%. Changes in thickness and mass of the film due to water vapor uptake are tracked using spectroscopic ellipsometry and quartz crystal microbalance with dissipation monitoring, respectively. Experimental data is evaluated by the quantitative Langmuir/Flory-Huggins/clustering model and the Brunauer-Emmett-Teller model. The isotherms coupled with the quantitative models unveil distinct regions of predominant sorption modes: specific sorption of water molecules below 10% RH, multilayer build-up between 10 to 75% RH, and clustering of water molecules above 75% RH. The study reveals the sorption mechanisms underlying the well-known water uptake behavior of TEMPO oxidized CNF directly at the gas-solid interface.

Sources, behaviors and degradation of dissolved organic matter in the East China Sea

NASA Astrophysics Data System (ADS)

Chen, Yan; Yang, Gui-Peng; Liu, Li; Zhang, Peng-Yan; Leng, Wei-Song

2016-03-01

Concentrations of dissolved organic carbon (DOC), dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and its major compound classes-total hydrolysable amino acids (THAA) were measured at 4 cross-shelf transects of the East China Sea in July 2011. Surface concentrations of DOC, DIN, DON and THAA at the nearshore stations were mostly in excess of those found at the offshore sites, indicating either substantial autochthonous production or allochthonous inputs from the Changjiang River. The vertical distributions of DOC, DON and THAA showed similar trends with higher values in the surface layer, whereas the elevated concentrations of DIN were observed in the bottom layer. Major constituents of THAA presented in the study area were glycine, serine, alanine, glutamic acid, aspartic acid and valine. The mole percentages of neutral amino acids increased from surface water to bottom water, whereas acidic and hydroxy amino acids decreased with the water depth. Concentrations of DOC and THAA were negatively correlated to the ΔDIN values (the difference between the real concentration and theoretical concentration), respectively, indicating the coupling relation between dissolved organic matter (DOM) remineralization and nutrient regeneration in the water column. The C/N ratios in the water column exhibited different characteristics with elevated values appearing in the surface and bottom layers. Box and whisker plots showed that both degradation index (DI) values and THAA yields displayed a decreasing trend from the surface layer to the bottom layer, implying increasing degradation with the water depth. Our data revealed that glycine and alanine increased in relative abundance with decreasing DI, while tyrosine, valine, phenylalanine and isoleucine increased with increasing DI.

Quantifying human impact on hydrological drought using an Earth System Model

NASA Astrophysics Data System (ADS)

van Huijgevoort, Marjolein; Chaney, Nathaniel; Malyshev, Sergey; Shevliakova, Elena; Milly, Chris

2017-04-01

Predicting the human impact on the present and future hydrological cycle remains a significant scientific challenge. Anthropogenic impact includes water management practices like diverting water for irrigation, abstraction of groundwater, and reservoirs. Hydrological extremes, in particular, are heavily affected by water management practices, due to the existing stress on the system during droughts and floods. Therefore, to prepare adaptation plans for hydrological extremes in the future, it is essential to account for water management and other human influences in Earth System Models. In this study we have implemented water management practices in the state-of-the-art GFDL land model, which includes terrestrial water, energy, and carbon balances. Both irrigation practices and reservoirs have been added in the land surface model component of the model. Irrigation amounts are determined from the soil water balance, the evaporative demand of the vegetation and fractional coverage of croplands. The resulting water demand is fulfilled by abstractions from surface water and groundwater. Reservoir outflow is dynamically coupled to the downstream water demand and available reservoir storage. Retrospective model simulations over the contiguous United States indicate a strong human influence on hydrological drought. A water management attribution analysis shows a significant impact on the water availability, mostly in the Midwest of the United States and California. Implementation of reservoirs alters the flow regime, thereby decreasing the short-term drought impact, however, in the case of multi-year drought, impacts are delayed due to the dependency on the reservoir outflow. Irrigation, on the other hand, decreases the water availability in rivers due to increased evapotranspiration leading to a higher drought impact. The average increase in evapotranspiration amounted up to 2 mm/day for cropland areas in California and Texas. Overall, the results show the importance of including water management in global scale models. This new modelling framework can be used to understand how humans will impact future water availability, water scarcity, and drought. Next steps will include coupled model simulations to investigate the human impact on feedbacks in land-atmosphere interactions.

Lesion dehydration rate changes with the surface layer thickness during enamel remineralization

NASA Astrophysics Data System (ADS)

Chang, Nai-Yuan N.; Jew, Jamison M.; Fried, Daniel

2018-02-01

A transparent highly mineralized outer surface zone is formed on caries lesions during remineralization that reduces the permeability to water and plaque generated acids. However, it has not been established how thick the surface zone should be to inhibit the penetration of these fluids. Near-IR (NIR) reflectance coupled with dehydration can be used to measure changes in the fluid permeability of lesions in enamel and dentin. Based on our previous studies, we postulate that there is a strong correlation between the surface layer thickness and the rate of dehydration. In this study, the rates of dehydration for simulated lesions in enamel with varying remineralization durations were measured. Reflectance imaging at NIR wavelengths from 1400-2300 nm, which coincides with higher water absorption and manifests the greatest sensitivity to contrast changes during dehydration measurements, was used to image simulated enamel lesions. The results suggest that the relationship between surface zone thickness and lesion permeability is highly non-linear, and that a small increase in the surface layer thickness may lead to a significant decrease in permeability.

Mapping Global Ocean Surface Albedo from Satellite Observations: Models, Algorithms, and Datasets

NASA Astrophysics Data System (ADS)

Li, X.; Fan, X.; Yan, H.; Li, A.; Wang, M.; Qu, Y.

2018-04-01

Ocean surface albedo (OSA) is one of the important parameters in surface radiation budget (SRB). It is usually considered as a controlling factor of the heat exchange among the atmosphere and ocean. The temporal and spatial dynamics of OSA determine the energy absorption of upper level ocean water, and have influences on the oceanic currents, atmospheric circulations, and transportation of material and energy of hydrosphere. Therefore, various parameterizations and models have been developed for describing the dynamics of OSA. However, it has been demonstrated that the currently available OSA datasets cannot full fill the requirement of global climate change studies. In this study, we present a literature review on mapping global OSA from satellite observations. The models (parameterizations, the coupled ocean-atmosphere radiative transfer (COART), and the three component ocean water albedo (TCOWA)), algorithms (the estimation method based on reanalysis data, and the direct-estimation algorithm), and datasets (the cloud, albedo and radiation (CLARA) surface albedo product, dataset derived by the TCOWA model, and the global land surface satellite (GLASS) phase-2 surface broadband albedo product) of OSA have been discussed, separately.

Effects of meteorological models on the solution of the surface energy balance and soil temperature variations in bare soils

NASA Astrophysics Data System (ADS)

Saito, Hirotaka; Šimůnek, Jiri

2009-07-01

SummaryA complete evaluation of the soil thermal regime can be obtained by evaluating the movement of liquid water, water vapor, and thermal energy in the subsurface. Such an evaluation requires the simultaneous solution of the system of equations for the surface water and energy balance, and subsurface heat transport and water flow. When only daily climatic data is available, one needs not only to estimate diurnal cycles of climatic data, but to calculate the continuous values of various components in the energy balance equation, using different parameterization methods. The objective of this study is to quantify the impact of the choice of different estimation and parameterization methods, referred together to as meteorological models in this paper, on soil temperature predictions in bare soils. A variety of widely accepted meteorological models were tested on the dataset collected at a proposed low-level radioactive-waste disposal site in the Chihuahua Desert in West Texas. As the soil surface was kept bare during the study, no vegetation effects were evaluated. A coupled liquid water, water vapor, and heat transport model, implemented in the HYDRUS-1D program, was used to simulate diurnal and seasonal soil temperature changes in the engineered cover installed at the site. The modified version of HYDRUS provides a flexible means for using various types of information and different models to evaluate surface mass and energy balance. Different meteorological models were compared in terms of their prediction errors for soil temperatures at seven observation depths. The results obtained indicate that although many available meteorological models can be used to solve the energy balance equation at the soil-atmosphere interface in coupled water, vapor, and heat transport models, their impact on overall simulation results varies. For example, using daily average climatic data led to greater prediction errors, while relatively simple meteorological models may significantly improve soil temperature predictions. On the other hand, while models for the albedo and soil emissivity had little impact on soil temperature predictions, the choice of the atmospheric emissivity models had a greater impact. A comparison of all the different models indicates that the error introduced at the soil atmosphere interface propagates to deeper layers. Therefore, attention needs to be paid not only to the precise determination of the soil hydraulic and thermal properties, but also to the selection of proper meteorological models for the components involved in the surface energy balance calculations.

Global land-atmosphere coupling associated with cold climate processes

NASA Astrophysics Data System (ADS)

Dutra, Emanuel

This dissertation constitutes an assessment of the role of cold processes, associated with snow cover, in controlling the land-atmosphere coupling. The work was based on model simulations, including offline simulations with the land surface model HTESSEL, and coupled atmosphere simulations with the EC-EARTH climate model. A revised snow scheme was developed and tested in HTESSEL and EC-EARTH. The snow scheme is currently operational at the European Centre for Medium-Range Weather Forecasts integrated forecast system, and in the default configuration of EC-EARTH. The improved representation of the snowpack dynamics in HTESSEL resulted in improvements in the near surface temperature simulations of EC-EARTH. The new snow scheme development was complemented with the option of multi-layer version that showed its potential in modeling thick snowpacks. A key process was the snow thermal insulation that led to significant improvements of the surface water and energy balance components. Similar findings were observed when coupling the snow scheme to lake ice, where lake ice duration was significantly improved. An assessment on the snow cover sensitivity to horizontal resolution, parameterizations and atmospheric forcing within HTESSEL highlighted the role of the atmospheric forcing accuracy and snowpack parameterizations in detriment of horizontal resolution over flat regions. A set of experiments with and without free snow evolution was carried out with EC-EARTH to assess the impact of the interannual variability of snow cover on near surface and soil temperatures. It was found that snow cover interannual variability explained up to 60% of the total interannual variability of near surface temperature over snow covered regions. Although these findings are model dependent, the results showed consistency with previously published work. Furthermore, the detailed validation of the snow dynamics simulations in HTESSEL and EC-EARTH guarantees consistency of the results.

Surface functionalization of Cu-Ni alloys via grafting of a bactericidal polymer for inhibiting biocorrosion by Desulfovibrio desulfuricans in anaerobic seawater.

PubMed

Yuan, S J; Liu, C K; Pehkonen, S O; Bai, R B; Neoh, K G; Ting, Y P; Kang, E T

2009-01-01

A novel surface modification technique was developed to provide a copper nickel alloy (M) surface with bactericidal and anticorrosion properties for inhibiting biocorrosion. 4-(chloromethyl)-phenyl tricholorosilane (CTS) was first coupled to the hydroxylated alloy surface to form a compact silane layer, as well as to confer the surface with chloromethyl functional groups. The latter allowed the coupling of 4-vinylpyridine (4VP) to generate the M-CTS-4VP surface with biocidal functionality. Subsequent surface graft polymerization of 4VP, in the presence of benzoyl peroxide (BPO) initiator, from the M-CTS-4VP surface produced the poly(4-vinylpyridine) (P(4VP)) grafted surface, or the M-CTS-P(4VP) surface. The pyridine nitrogen moieties on the M-CTS-P(4VP) surface were quaternized with hexylbromide to produce a high concentration of quaternary ammonium groups. Each surface functionalization step was ascertained by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements. The alloy with surface-quaternized pyridinium cation groups (N+) exhibited good bactericidal efficiency in a Desulfovibrio desulfuricans-inoculated seawater-based modified Barr's medium, as indicated by viable cell counts and fluorescence microscopy (FM) images of the surface. The anticorrosion capability of the organic layers was verified by the polarization curve and electrochemical impedance spectroscopy (EIS) measurements. In comparison, the pristine (surface hydroxylated) Cu-Ni alloy was found to be readily susceptible to biocorrosion under the same environment.

Maintenance of Coastal Surface Blooms by Surface Temperature Stratification and Wind Drift

PubMed Central

Ruiz-de la Torre, Mary Carmen; Maske, Helmut; Ochoa, José; Almeda-Jauregui, César O.

2013-01-01

Algae blooms are an increasingly recurrent phenomenon of potentially socio-economic impact in coastal waters globally and in the coastal upwelling region off northern Baja California, Mexico. In coastal upwelling areas the diurnal wind pattern is directed towards the coast during the day. We regularly found positive Near Surface Temperature Stratification (NSTS), the resulting density stratification is expected to reduce the frictional coupling of the surface layer from deeper waters and allow for its more efficient wind transport. We propose that the net transport of the top layer of approximately 2.7 kilometers per day towards the coast helps maintain surface blooms of slow growing dinoflagellate such as Lingulodinium polyedrum. We measured: near surface stratification with a free-rising CTD profiler, trajectories of drifter buoys with attached thermographs, wind speed and direction, velocity profiles via an Acoustic Doppler Current Profiler, Chlorophyll and cell concentration from water samples and vertical migration using sediment traps. The ADCP and drifter data agree and show noticeable current shear within the first meters of the surface where temperature stratification and high cell densities of L. polyedrum were found during the day. Drifters with 1m depth drogue moved towards the shore, whereas drifters at 3 and 5 m depth showed trajectories parallel or away from shore. A small part of the surface population migrated down to the sea floor during night thus reducing horizontal dispersion. The persistent transport of the surface bloom population towards shore should help maintain the bloom in favorable environmental conditions with high nutrients, but also increasing the potential socioeconomic impact of the blooms. The coast wise transport is not limited to blooms but includes all dissolved and particulate constituents in surface waters. PMID:23593127

Maintenance of coastal surface blooms by surface temperature stratification and wind drift.

PubMed

Ruiz-de la Torre, Mary Carmen; Maske, Helmut; Ochoa, José; Almeda-Jauregui, César O

2013-01-01

Algae blooms are an increasingly recurrent phenomenon of potentially socio-economic impact in coastal waters globally and in the coastal upwelling region off northern Baja California, Mexico. In coastal upwelling areas the diurnal wind pattern is directed towards the coast during the day. We regularly found positive Near Surface Temperature Stratification (NSTS), the resulting density stratification is expected to reduce the frictional coupling of the surface layer from deeper waters and allow for its more efficient wind transport. We propose that the net transport of the top layer of approximately 2.7 kilometers per day towards the coast helps maintain surface blooms of slow growing dinoflagellate such as Lingulodinium polyedrum. We measured: near surface stratification with a free-rising CTD profiler, trajectories of drifter buoys with attached thermographs, wind speed and direction, velocity profiles via an Acoustic Doppler Current Profiler, Chlorophyll and cell concentration from water samples and vertical migration using sediment traps. The ADCP and drifter data agree and show noticeable current shear within the first meters of the surface where temperature stratification and high cell densities of L. polyedrum were found during the day. Drifters with 1m depth drogue moved towards the shore, whereas drifters at 3 and 5 m depth showed trajectories parallel or away from shore. A small part of the surface population migrated down to the sea floor during night thus reducing horizontal dispersion. The persistent transport of the surface bloom population towards shore should help maintain the bloom in favorable environmental conditions with high nutrients, but also increasing the potential socioeconomic impact of the blooms. The coast wise transport is not limited to blooms but includes all dissolved and particulate constituents in surface waters.

Multi-objective analysis of the conjunctive use of surface water and groundwater in a multisource water supply system

NASA Astrophysics Data System (ADS)

Vieira, João; da Conceição Cunha, Maria

2017-04-01

A multi-objective decision model has been developed to identify the Pareto-optimal set of management alternatives for the conjunctive use of surface water and groundwater of a multisource urban water supply system. A multi-objective evolutionary algorithm, Borg MOEA, is used to solve the multi-objective decision model. The multiple solutions can be shown to stakeholders allowing them to choose their own solutions depending on their preferences. The multisource urban water supply system studied here is dependent on surface water and groundwater and located in the Algarve region, southernmost province of Portugal, with a typical warm Mediterranean climate. The rainfall is low, intermittent and concentrated in a short winter, followed by a long and dry period. A base population of 450 000 inhabitants and visits by more than 13 million tourists per year, mostly in summertime, turns water management critical and challenging. Previous studies on single objective optimization after aggregating multiple objectives together have already concluded that only an integrated and interannual water resources management perspective can be efficient for water resource allocation in this drought prone region. A simulation model of the multisource urban water supply system using mathematical functions to represent the water balance in the surface reservoirs, the groundwater flow in the aquifers, and the water transport in the distribution network with explicit representation of water quality is coupled with Borg MOEA. The multi-objective problem formulation includes five objectives. Two objective evaluate separately the water quantity and the water quality supplied for the urban use in a finite time horizon, one objective calculates the operating costs, and two objectives appraise the state of the two water sources - the storage in the surface reservoir and the piezometric levels in aquifer - at the end of the time horizon. The decision variables are the volume of withdrawals from each water source in each time step (i.e., reservoir diversion and groundwater pumping). The results provide valuable information for analysing the impacts of the conjunctive use of surface water and groundwater. For example, considering a drought scenario, the results show how the same level of total water supplied can be achieved by different management alternatives with different impact on the water quality, costs, and the state of the water sources at the end of the time horizon. The results allow also the clear understanding of the potential benefits from the conjunctive use of surface water and groundwater thorough the mitigation of the variation in the availability of surface water, improving the water quantity and/or water quality delivered to the users, or the better adaptation of such systems to a changing world.

Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water

NASA Astrophysics Data System (ADS)

van der Grift, B.; Rozemeijer, J. C.; Griffioen, J.; van der Velde, Y.

2014-11-01

The retention of phosphorus in surface waters through co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from groundwater into surface water in an agricultural experimental catchment of a small lowland river. We physically separated tube drain effluent from groundwater discharge before it entered a ditch in an agricultural field. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and surface water, we investigated Fe(II) oxidation kinetics and P immobilization processes. The oxidation rate inferred from our field measurements closely agreed with the general rate law for abiotic oxidation of Fe(II) by O2. Seasonal changes in climatic conditions affected the Fe(II) oxidation process. Lower pH and lower temperatures in winter (compared to summer) resulted in low Fe oxidation rates. After exfiltration to the surface water, it took a couple of days to more than a week before complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates were much higher. The Fe concentrations in the exfiltrated groundwater were low, indicating that dissolved Fe(II) is completely oxidized prior to inflow into a ditch. While the Fe oxidation rates reduce drastically from summer to winter, P concentrations remained high in the groundwater and an order of magnitude lower in the surface water throughout the year. This study shows very fast immobilization of dissolved P during the initial stage of the Fe(II) oxidation process which results in P-depleted water before Fe(II) is completely depleted. This cannot be explained by surface complexation of phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox gradients seems an important geochemical mechanism in the transformation of dissolved phosphate to structural phosphate and, therefore, a major control on the P retention in natural waters that drain anaerobic aquifers.

Using a spatially-distributed hydrologic biogeochemistry model with a nitrogen transport module to study the spatial variation of carbon processes in a Critical Zone Observatory

DOE PAGES

Shi, Yuning; Eissenstat, David M.; He, Yuting; ...

2018-05-12

Terrestrial carbon processes are affected by soil moisture, soil temperature, nitrogen availability and solar radiation, among other factors. Most of the current ecosystem biogeochemistry models represent one point in space, and have limited characterization of hydrologic processes. Therefore these models can neither resolve the topographically driven spatial variability of water, energy, and nutrient, nor their effects on carbon processes. A spatially-distributed land surface hydrologic biogeochemistry model, Flux-PIHM-BGC, is developed by coupling the Biome-BGC model with a physically-based land surface hydrologic model, Flux-PIHM. In the coupled system, each Flux-PIHM model grid couples a 1-D Biome-BGC model. In addition, a topographic solarmore » radiation module and an advection-driven nitrogen transport module are added to represent the impact of topography on nutrient transport and solar energy distribution. Because Flux-PIHM is able to simulate lateral groundwater flow and represent the land surface heterogeneities caused by topography, Flux-PIHM-BGC is capable of simulating the complex interaction among water, energy, nutrient, and carbon in time and space. The Flux-PIHM-BGC model is tested at the Susquehanna/Shale Hills Critical Zone Observatory. Model results show that distributions of carbon and nitrogen stocks and fluxes are strongly affected by topography and landscape position, and tree growth is nitrogen limited. The predicted aboveground and soil carbon distributions generally agree with the macro patterns observed. Although the model underestimates the spatial variation, the predicted watershed average values are close to the observations. Lastly, the coupled Flux-PIHM-BGC model provides an important tool to study spatial variations in terrestrial carbon and nitrogen processes and their interactions with environmental factors, and to predict the spatial structure of the responses of ecosystems to climate change.« less

Using a spatially-distributed hydrologic biogeochemistry model with a nitrogen transport module to study the spatial variation of carbon processes in a Critical Zone Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Yuning; Eissenstat, David M.; He, Yuting

Terrestrial carbon processes are affected by soil moisture, soil temperature, nitrogen availability and solar radiation, among other factors. Most of the current ecosystem biogeochemistry models represent one point in space, and have limited characterization of hydrologic processes. Therefore these models can neither resolve the topographically driven spatial variability of water, energy, and nutrient, nor their effects on carbon processes. A spatially-distributed land surface hydrologic biogeochemistry model, Flux-PIHM-BGC, is developed by coupling the Biome-BGC model with a physically-based land surface hydrologic model, Flux-PIHM. In the coupled system, each Flux-PIHM model grid couples a 1-D Biome-BGC model. In addition, a topographic solarmore » radiation module and an advection-driven nitrogen transport module are added to represent the impact of topography on nutrient transport and solar energy distribution. Because Flux-PIHM is able to simulate lateral groundwater flow and represent the land surface heterogeneities caused by topography, Flux-PIHM-BGC is capable of simulating the complex interaction among water, energy, nutrient, and carbon in time and space. The Flux-PIHM-BGC model is tested at the Susquehanna/Shale Hills Critical Zone Observatory. Model results show that distributions of carbon and nitrogen stocks and fluxes are strongly affected by topography and landscape position, and tree growth is nitrogen limited. The predicted aboveground and soil carbon distributions generally agree with the macro patterns observed. Although the model underestimates the spatial variation, the predicted watershed average values are close to the observations. Lastly, the coupled Flux-PIHM-BGC model provides an important tool to study spatial variations in terrestrial carbon and nitrogen processes and their interactions with environmental factors, and to predict the spatial structure of the responses of ecosystems to climate change.« less

Mining Environmental Data from a Coupled Modelling System to Examine the Impact of Agricultural Management Practices on Groundwater and Air Quality

NASA Astrophysics Data System (ADS)

Garcia, V.; Cooter, E. J.; Hayes, B.; Murphy, M. S.; Bash, J. O.

2014-12-01

Excess nitrogen (N) resulting from current agricultural management practices can leach into sources of drinking water as nitrate, increasing human health risks of 'blue baby syndrome', hypertension, and some cancers and birth defects. Nitrogen also enters the atmosphere from land surfaces forming air pollution increasing human health risks of pulmonary and cardio-vascular disease. Characterizing and attributing nitrogen from agricultural management practices is difficult due to the complex and inter-related chemical and biological reactions associated with the nitrogen cascade. Coupled physical process-based models, however, present new opportunities to investigate relationships among environmental variables on new scales; particularly because they link emission sources with meteorology and the pollutant concentration ultimately found in the environment. In this study, we applied a coupled meteorology (NOAA-WRF), agricultural (USDA-EPIC) and air quality modelling system (EPA-CMAQ) to examine the impact of nitrogen inputs from corn production on ecosystem and human health and wellbeing. The coupled system accounts for the nitrogen flux between the land surface and air, and the soil surface and groundwater, providing a unique opportunity to examine the effect of management practices such as type and timing of fertilization, tilling and irrigation on both groundwater and air quality across the conterminous US. In conducting the study, we first determined expected relationships based on literature searches and then identified model variables as direct or surrogate variables. We performed extensive and methodical multi-variate regression modelling and variable selection to examine associations between agricultural management practices and environmental condition. We then applied the regression model to predict and contrast pollution levels between two corn production scenarios (Figure 1). Finally, we applied published health functions (e.g., spina bifida and cardio-vascular mortality rates) and economic impact functions (e.g., loss of work/school days, decontamination of drinking water wells). The results of this analysis will be presented at the conference.

Ab initio simulations of water splitting on hematite

NASA Astrophysics Data System (ADS)

Seriani, Nicola

2017-11-01

In recent years, hematite has attracted great interest as a photocatalyst for water splitting, but many questions remain unanswered about the mechanisms and the main limiting factors. For this reason, density functional theory has been used to understand the optical, electronic and chemical properties of this material at an atomistic level. Bulk doping can be used to reduce the band gap, and to increase photoabsorption and charge mobility. Charge transport takes place through adiabatic polaron hopping. The stable (0 0 0 1) surface has a stoichiometric termination when exposed to oxygen, it becomes hydroxylated in water, and it has an oxygen-rich termination under illumination in a photoelectrochemical setup. On the oxygen-rich termination, surface states are present that might act as recombination centres for electrons and holes. On the contrary, on the hydroxylated termination surface states appear only on reaction intermediates. The intrinsic surface states disappear in the presence of an overlayer of gallium oxide. The reaction of water oxidation is assumed to proceed by four proton-coupled electron transfers and it is shown to involve a nucleophilic attack with the formation of an OOH group. Calculated overpotentials are in the range of 0.5-0.6 V. Open questions and future research directions are briefly discussed.

Ultra-trace levels analysis of microcystins and nodularin in surface water by on-line solid-phase extraction with high-performance liquid chromatography tandem mass spectrometry.

PubMed

Balest, Lydia; Murgolo, Sapia; Sciancalepore, Lucia; Montemurro, Patrizia; Abis, Pier Paolo; Pastore, Carlo; Mascolo, Giuseppe

2016-06-01

An on-line solid phase extraction coupled with high-performance liquid chromatography in tandem with mass spectrometry (on-line SPE/HPLC/MS-MS) method for the determination of five microcystins and nodularin in surface waters at submicrogram per liter concentrations has been optimized. Maximum recoveries were achieved by carefully optimizing the extraction sample volume, loading solvent, wash solvent, and pH of the sample. The developed method was also validated according to both UNI EN ISO IEC 17025 and UNICHIM guidelines. Specifically, ten analytical runs were performed at three different concentration levels using a reference mix solution containing the six analytes. The method was applied for monitoring the concentrations of microcystins and nodularin in real surface water during a sampling campaign of 9 months in which the ELISA method was used as standard official method. The results of the two methods were compared showing good agreement when the highest concentration values of MCs were found. Graphical abstract An on-line SPE/HPLC/MS-MS method for the determination of five microcystins and nodularin in surface waters at sub μg L(-1) was optimized and compared with ELISA assay method for real samples.

Polystyrene/wood composites and hydrophobic wood coatings from water-based hydrophilic-hydrophobic block copolymers

Treesearch

Marja-Leena Kosonen; Bo Wang; Gerard T. Caneba; Douglas J. Gardner; Tim G. Rials

2000-01-01

The combination of synthetic thermoplastic polymers and wood is normally problematic because wood surfaces are hydrophilic while typical thermoplastic polymers are hydrophobic. A possible solution is to use block copolymer coupling agents. In this work we show the use of a potentially useful synthetic method of producing hydrophilic-hydrophobic block copolymers as...

Submesoscale Flows and Mixing in the Ocean Surface Layer Using the Regional Oceanic Modeling System (ROMS)

DTIC Science & Technology

2013-09-30

chemical cycles, water quality, blooms , micro-nutrients, larval dispersal, biome transitions, and coupling to higher tropic levels. We collaborate with...Kurian, 2012: Heat balance and eddies in the Peru- Chile Current System. Climate Dynamics 39, 509-529, doi:10.1007/s00382-011-1170-6. Colas, F., X

76 FR 56607 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List 42 Great...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-13

... scientific or commercial information indicating that the petitioned action may be warranted. We are to base... asserts that springsnails are inherently vulnerable to extirpation due to their isolation and limited... surface waters by large expanses of dry land. This isolation and limited distribution, coupled with low...

Use of Linear Prediction Uncertainty Analysis to Guide Conditioning of Models Simulating Surface-Water/Groundwater Interactions

NASA Astrophysics Data System (ADS)

Hughes, J. D.; White, J.; Doherty, J.

2011-12-01

Linear prediction uncertainty analysis in a Bayesian framework was applied to guide the conditioning of an integrated surface water/groundwater model that will be used to predict the effects of groundwater withdrawals on surface-water and groundwater flows. Linear prediction uncertainty analysis is an effective approach for identifying (1) raw and processed data most effective for model conditioning prior to inversion, (2) specific observations and periods of time critically sensitive to specific predictions, and (3) additional observation data that would reduce model uncertainty relative to specific predictions. We present results for a two-dimensional groundwater model of a 2,186 km2 area of the Biscayne aquifer in south Florida implicitly coupled to a surface-water routing model of the actively managed canal system. The model domain includes 5 municipal well fields withdrawing more than 1 Mm3/day and 17 operable surface-water control structures that control freshwater releases from the Everglades and freshwater discharges to Biscayne Bay. More than 10 years of daily observation data from 35 groundwater wells and 24 surface water gages are available to condition model parameters. A dense parameterization was used to fully characterize the contribution of the inversion null space to predictive uncertainty and included bias-correction parameters. This approach allows better resolution of the boundary between the inversion null space and solution space. Bias-correction parameters (e.g., rainfall, potential evapotranspiration, and structure flow multipliers) absorb information that is present in structural noise that may otherwise contaminate the estimation of more physically-based model parameters. This allows greater precision in predictions that are entirely solution-space dependent, and reduces the propensity for bias in predictions that are not. Results show that application of this analysis is an effective means of identifying those surface-water and groundwater data, both raw and processed, that minimize predictive uncertainty, while simultaneously identifying the maximum solution-space dimensionality of the inverse problem supported by the data.

A new class of draw solutions for minimizing reverse salt flux to improve forward osmosis desalination.

PubMed

Nguyen, Hau Thi; Nguyen, Nguyen Cong; Chen, Shiao-Shing; Ngo, Huu Hao; Guo, Wenshan; Li, Chi-Wang

2015-12-15

The applications of forward osmosis (FO) have been hindered because of the lack of an optimal draw solution. The reverse salt flux from the draw solution not only reduces the water flux but also increases the cost of draw solute replenishment. Therefore, in this study, Tergitol NP7 and NP9 with a long straight carbon chain and low critical micelle concentration (CMC) were coupled with highly charged ethylenediaminetetraacetic acid (EDTA) as an innovative draw solution to minimize reverse salt diffusion in FO for the first time. The results showed that the lowest reverse salt flux of 0.067 GMH was observed when 0.1M EDTA-2Na coupled with 15mM NP7 was used as a draw solution and deionized water was used as a feed solution in FO mode (active layer facing with the feed solution). This is due to the hydrophobic interaction between the tails of NP7 and the FO membrane, thus creating layers on the membrane surface and constricting the FO membrane pores. Moreover, 1M EDTA-2Na coupled with 15mM NP7 is promising as an optimal draw solution for brackish water and sea water desalination. Average water fluxes of 7.68, 6.78, and 5.95 LMH were achieved when brackish water was used as a feed solution (5, 10, and 20g/L NaCl), and an average water flux of 3.81 LMH was achieved when sea water was used as a feed solution (35g/L NaCl). The diluted draw solution was recovered using a nanofiltration (NF-TS80) membrane with a high efficiency of 95% because of the high charge and large size of the draw solution. Copyright © 2015 Elsevier B.V. All rights reserved.

Progress in studies on hydrological impacts of degrading permafrost in the Source Area of Yellow River on NE Qinghai-Tibet Plateau, SW China

NASA Astrophysics Data System (ADS)

Jin, H.; Ma, Q.; Jin, X.

2017-12-01

Permafrost degradation substantially impacts hydrological processes in the Source Area of the Yellow River (SAYR). Deepening active layer has directly led to a reduction of surface runoffs, alters the generation and dynamics of slope runoffs and groundwater, leading to a deepening of groundwater flow paths. At present, however, there is only a limited understanding of the hydrological impact mechanisms of degrading permafrost. On the basis of analyzing and evaluating the current states, changing history and developing trends of climate, permafrost and hydrological processes, this program aims at further and better quantifying the nature of these mechanisms linking the degrading permafrost with changing hydrological processes. The key scientific themes for this research are the characterization of interactions between ground freezing-thawing and hydrogeology in the SAYR. For this study, a coupling is made between geothermal states and the occurrences of taliks in river systems, in order to understand how expanding taliks control groundwater and surface-water interactions and how these interactions might intensify or weaken when the climate warms and dries persistently. Numerical models include freeze-thaw dynamics coupled to groundwater and surface flow processes. For the proper parameterization of these models, field and laboratory studies are conducted with a focus on the SAYR. Geophysical investigations are employed for mapping permafrost distribution in relation to landscape elements. Boreholes and water wells and observation sites for the hydrothermal processes and water tables are used for establishing the current thermal state of frozen ground and talik and monitor their changes over time, and serve to ground-truth surface geophysical observations. Boreholes and wellbores, water wells and active layer sites have provided access to the permafrost and aquifer systems, allowing the dating of ground-water and -ice and soil strata for elucidating the regional hydrogeological system underlying the SAYR, and groundwater recharge mechanisms. The project plans to quantitatively study the impacting mechanisms of degrading frozen ground on changes in hydrological processes and systems in the SAYR.

Evaluation of on-line concentration coupled to liquid chromatography tandem mass spectrometry for the quantification of neonicotinoids and fipronil in surface water and tap water.

PubMed

Montiel-León, Juan Manuel; Duy, Sung Vo; Munoz, Gabriel; Amyot, Marc; Sauvé, Sébastien

2018-04-01

A study was initiated to investigate a fast and reliable method for the determination of selected systemic insecticides in water matrixes and to evaluate potential sources of bias in their analysis. Acetamiprid, clothianidin, desnitro-imidacloprid, dinotefuran, fipronil, imidacloprid, nitenpyram, thiacloprid, and thiamethoxam were amenable to analysis via on-line sample enrichment hyphenated to ultra-high-performance liquid chromatography tandem mass spectrometry. The selection of on-line solid-phase extraction parameters was dictated by a multicriterion desirability approach. A 2-mL on-line injection volume with a 1500 μL min -1 loading flow rate met the objectives sought in terms of chromatographic requirements, extraction efficiency, sensitivity, and precision. A total analysis time of 8 min per sample was obtained with method limits of detection in the range of 0.1-5 ng L -1 for the scope of targeted analytes. Automation at the sample concentration step yielded intraday and interday precisions in the range of 1-23 and 2-26%, respectively. Factors that could affect the whole method accuracy were further evaluated in matrix-specific experiments. The impact of the initial filtration step on analyte recovery was evaluated in ultra-pure water, tap water, and surface water. Out of the nine membranes tested, glass fiber filters and polyester filters appeared as the most appropriate materials. Sample storage stability was also investigated across the three matrix types; the targeted analytes displayed suitable stability during 28 days at either 4 °C or - 20 °C, with little deviations (± 10%) with respect to the initial T 0 concentration. Method applicability was demonstrated in a range of tap water and surface water samples from the province of Québec, Canada. Results from the present survey indicated a predominance of thiamethoxam (< 0.5-10 and 3-61 ng L -1 in tap water and river water, respectively), clothianidin (< 0.5-6 and 2-88 ng L -1 in tap water and river water, respectively), and imidacloprid (< 0.1-1 and 0.8-38 ng L -1 in tap water and river water, respectively) among the targeted analytes. Graphical abstract ᅟ Development of solid-phase extraction coupled on-line to UHPLC-MS/MS for the rapid screening of systemic insecticides in water.

Use of pressure manifestations following the water plasma expansion for phytomass disintegration.

PubMed

Maroušek, Josef; Kwan, Jason Tai Hong

2013-01-01

A prototype capable of generating underwater high-voltage discharges (3.5 kV) coupled with water plasma expansion was constructed. The level of phytomass disintegration caused by transmission of the pressure shockwaves (50-60 MPa) followed by this expansion was analyzed using gas adsorption techniques. The dynamics of the external surface area and the micropore volume on multiple pretreatment stages of maize silage and sunflower seeds was approximated with robust analytical techniques. The multiple increases on the reaction surface were manifest in up to a 15% increase in cumulative methane production, which was itself manifest in the overall acceleration of the anaerobic fermentation process. Disintegration of the sunflower seeds allowed up to 45% higher oil yields using the same operating pressure.

Non-renewable water use on the globe and its implication to sea level change

NASA Astrophysics Data System (ADS)

Oki, T.; Pokhrel, Y. N.; Hanasaki, N.; Koirala, S.; Kanae, S.

2012-12-01

The real hydrological cycles on the Earth are not natural anymore. Global hydrological model simulations of the water cycle and available water resources should have an ability to consider the effects of human interventions on hydrological cycles. Anthropogenic activity modules, such as reservoir operation, crop growth and water demand in croplands, and environmental flows, were incorporated into a land surface model to form a new model, MAT-HI. Total terrestrial water storages (TWS) in large river basins were estimated using the new model by off-line simulation, and compared with the TWS observed by GRACE for 2002-2007. MAT-HI was further coupled with a module representing the ground water level fluctuations, and consists a new land surface scheme HiGW-MAT (Human Intervention and Ground Water coupled MATSIRO). HiGW-MAT is also associated with a scheme tracing the origin and flow path with the consideration on the sources of water withdrawal from stream flow, medium-size reservoirs and nonrenewable groundwater in addition to precipitation to croplands which enabled the assessment of the origin of water producing major crops. Areas highly dependent on nonrenewable groundwater are detected in the Pakistan, Bangladesh, Western part of India, north and western parts of China, some regions in the Arabian Peninsula, and the western part of the United States through Mexico. Cumulative nonrenewable groundwater withdrawals estimated by the model are corresponding fairly well with the country statistics of total groundwater withdrawals. Ground water table depletions in large aquifers in US estimated by HiGW-MAT were compared with in-situ observational data, and the correspondences are very good. Mean global exploitation of ground water for 2000 estimated by HiGW-MAT is 360 km3/y as an excess of ground water withdrawal over natural recharge into aquifer. This unsustainable groundwater use, together with artificial reservoir water impoundment, climate-driven changes in terrestrial water storage and the loss of water from closed basins, could have contributed a sea-level rise of about 0.77mm/y between 1961 and 2003, about 42% of the observed sea-level rise.

An improved understanding of the natural resonances of moonpools contained within floating rigid-bodies: Theory and application to oscillating water column devices

DOE PAGES

Bull, Diana L.

2015-09-23

The fundamental interactions between waves, a floating rigid-body, and a moonpool that is selectively open to atmosphere or enclosed to purposefully induce pressure fluctuations are investigated. The moonpool hydrodynamic characteristics and the hydrodynamic coupling to the rigid-body are derived implicitly through reciprocity relations on an array of field points. By modeling the free surface of the moonpool in this manner, an explicit hydrodynamic coupling term is included in the equations of motion. This coupling results in the migration of the moonpool's natural resonance frequency from the piston frequency to a new frequency when enclosed in a floating rigid-body. Two geometriesmore » that highlight distinct aspects of marine vessels and oscillating water column (OWC) renewable energy devices are analyzed to reveal the coupled natural resonance migration. The power performance of these two OWCs in regular waves is also investigated. The air chamber is enclosed and a three-dimensional, linear, frequency domain performance model that links the rigid-body to the moonpool through a linear resistive control strategy is detailed. Furthermore, an analytic expression for the optimal linear resistive control values in regular waves is presented.« less

An improved understanding of the natural resonances of moonpools contained within floating rigid-bodies: Theory and application to oscillating water column devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bull, Diana L.

The fundamental interactions between waves, a floating rigid-body, and a moonpool that is selectively open to atmosphere or enclosed to purposefully induce pressure fluctuations are investigated. The moonpool hydrodynamic characteristics and the hydrodynamic coupling to the rigid-body are derived implicitly through reciprocity relations on an array of field points. By modeling the free surface of the moonpool in this manner, an explicit hydrodynamic coupling term is included in the equations of motion. This coupling results in the migration of the moonpool's natural resonance frequency from the piston frequency to a new frequency when enclosed in a floating rigid-body. Two geometriesmore » that highlight distinct aspects of marine vessels and oscillating water column (OWC) renewable energy devices are analyzed to reveal the coupled natural resonance migration. The power performance of these two OWCs in regular waves is also investigated. The air chamber is enclosed and a three-dimensional, linear, frequency domain performance model that links the rigid-body to the moonpool through a linear resistive control strategy is detailed. Furthermore, an analytic expression for the optimal linear resistive control values in regular waves is presented.« less

Impact of Soil Moisture Assimilation on Land Surface Model Spin-Up and Coupled LandAtmosphere Prediction

NASA Technical Reports Server (NTRS)

Santanello, Joseph A., Jr.; Kumar, Sujay V.; Peters-Lidard, Christa D.; Lawston, P.

2016-01-01

Advances in satellite monitoring of the terrestrial water cycle have led to a concerted effort to assimilate soil moisture observations from various platforms into offline land surface models (LSMs). One principal but still open question is that of the ability of land data assimilation (LDA) to improve LSM initial conditions for coupled short-term weather prediction. In this study, the impact of assimilating Advanced Microwave Scanning Radiometer for EOS (AMSR-E) soil moisture retrievals on coupled WRF Model forecasts is examined during the summers of dry (2006) and wet (2007) surface conditions in the southern Great Plains. LDA is carried out using NASAs Land Information System (LIS) and the Noah LSM through an ensemble Kalman filter (EnKF) approach. The impacts of LDA on the 1) soil moisture and soil temperature initial conditions for WRF, 2) land-atmosphere coupling characteristics, and 3) ambient weather of the coupled LIS-WRF simulations are then assessed. Results show that impacts of soil moisture LDA during the spin-up can significantly modify LSM states and fluxes, depending on regime and season. Results also indicate that the use of seasonal cumulative distribution functions (CDFs) is more advantageous compared to the traditional annual CDF bias correction strategies. LDA performs consistently regardless of atmospheric forcing applied, with greater improvements seen when using coarser, global forcing products. Downstream impacts on coupled simulations vary according to the strength of the LDA impact at the initialization, where significant modifications to the soil moisture flux- PBL-ambient weather process chain are observed. Overall, this study demonstrates potential for future, higher-resolution soil moisture assimilation applications in weather and climate research.

Climatic change impacts on water balance of the Upper Jordan River

NASA Astrophysics Data System (ADS)

Heckl, A.; Kunstmann, H.

2009-04-01

The Eastern Mediterranean and Near East (EM/NE) is an extremely water scarce environment. It is expected that problems will increase due to climate change and population growth. The impact of climate change on water availability in EM/NE and in particular the Jordan River catchment is investigated in this study. Focus is set on the Upper Jordan River catchment (UJC) as it provides 1/3rd of freshwater resources in Israel and Palestine. It is a hydro-geologically extremely complex region with karstic groundwater flow and an orography with steep gradients. The methods used are high resolution coupled regional climate - hydrology simulations. Two IPCC scenarios (A2 and B2) of the global climate model ECHAM4 have been dynamically downscaled using the non-hydrostatic meteorological model MM5 in two nesting steps with resolutions of 54x54 km2 and 18x18 km2 for the period 1961-2099, whereby the time slice 1961-1989 represents the current climate. The meteorological fields are used to drive the physically based hydrological model WaSiM applied to the UJC. The hydrological model computes in detail the surface and subsurface water flow and water balance in a horizontal resolution of 450 x 450 m2 and dynamically couples to a 2-dim numerical groundwater model. Parameters like surface runoff, groundwater recharge, soil moisture and evapotranspiration can be extracted. Results show in both scenarios increasing yearly mean temperatures up to 4-5 K until 2099 and decreasing yearly precipitation amounts up to 25% (scenario A2). The effect on the water balance of the UJC are reduced discharge and groundwater recharge, increased evaporation and reduction of snow cover in the mountains which usually serves as an important freshwater reservoir for the summer discharge.

Effect of medium on friction and wear properties of compacted graphite cast iron processed by biomimetic coupling laser remelting process

NASA Astrophysics Data System (ADS)

Guo, Qing-chun; Zhou, Hong; Wang, Cheng-tao; Zhang, Wei; Lin, Peng-yu; Sun, Na; Ren, Luquan

2009-04-01

Stimulated by the cuticles of soil animals, an attempt to improve the wear resistance of compact graphite cast iron (CGI) with biomimetic units on the surface was made by using a biomimetic coupled laser remelting process in air and various thicknesses water film, respectively. The microstructures of biomimetic units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases in the melted zone. Microhardness was measured and the wear behaviors of biomimetic specimens as functions of different mediums as well as various water film thicknesses were investigated under dry sliding condition, respectively. The results indicated that the microstructure zones in the biomimetic specimens processed with water film are refined compared with that processed in air and had better wear resistance increased by 60%, the microhardness of biomimetic units has been improved significantly. The application of water film provided finer microstructures and much more regular grain shape in biomimetic units, which played a key role in improving the friction properties and wear resistance of CGI.

Potential regulation on the climatic effect of Tibetan Plateau heating by tropical air-sea coupling in regional models

NASA Astrophysics Data System (ADS)

Wang, Ziqian; Duan, Anmin; Yang, Song

2018-05-01

Based on the conventional weather research and forecasting (WRF) model and the air-sea coupled mode WRF-OMLM, we investigate the potential regulation on the climatic effect of Tibetan Plateau (TP) heating by the air-sea coupling over the tropical Indian Ocean and western Pacific. Results indicate that the TP heating significantly enhances the southwesterly monsoon circulation over the northern Indian Ocean and the South Asia subcontinent. The intensified southwesterly wind cools the sea surface mainly through the wind-evaporation-SST (sea surface temperature) feedback. Cold SST anomaly then weakens monsoon convective activity, especially that over the Bay of Bengal, and less water vapor is thus transported into the TP along its southern slope from the tropical oceans. As a result, summer precipitation decreases over the TP, which further weakens the TP local heat source. Finally, the changed TP heating continues to influence the summer monsoon precipitation and atmospheric circulation. To a certain extent, the air-sea coupling over the adjacent oceans may weaken the effect of TP heating on the mean climate in summer. It is also implied that considerations of air-sea interaction are necessary in future simulation studies of the TP heating effect.

Validation of the Fully-Coupled Air-Sea-Wave COAMPS System

NASA Astrophysics Data System (ADS)

Smith, T.; Campbell, T. J.; Chen, S.; Gabersek, S.; Tsu, J.; Allard, R. A.

2017-12-01

A fully-coupled, air-sea-wave numerical model, COAMPS®, has been developed by the Naval Research Laboratory to further enhance understanding of oceanic, atmospheric, and wave interactions. The fully-coupled air-sea-wave system consists of an atmospheric component with full physics parameterizations, an ocean model, NCOM (Navy Coastal Ocean Model), and two wave components, SWAN (Simulating Waves Nearshore) and WaveWatch III. Air-sea interactions between the atmosphere and ocean components are accomplished through bulk flux formulations of wind stress and sensible and latent heat fluxes. Wave interactions with the ocean include the Stokes' drift, surface radiation stresses, and enhancement of the bottom drag coefficient in shallow water due to the wave orbital velocities at the bottom. In addition, NCOM surface currents are provided to SWAN and WaveWatch III to simulate wave-current interaction. The fully-coupled COAMPS system was executed for several regions at both regional and coastal scales for the entire year of 2015, including the U.S. East Coast, Western Pacific, and Hawaii. Validation of COAMPS® includes observational data comparisons and evaluating operational performance on the High Performance Computing (HPC) system for each of these regions.

Simultaneous determination of estrogenic odorant alkylphenols, chlorophenols, and their derivatives in water using online headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

PubMed

Yuan, Su-Fen; Liu, Ze-Hua; Lian, Hai-Xian; Yang, Chuangtao; Lin, Qing; Yin, Hua; Dang, Zhi

2016-10-01

A simple online headspace solid-phase microextraction (HS-SPME) coupled with the gas chromatography-mass spectrometry (GC-MS) method was developed for simultaneous determination of trace amounts of nine estrogenic odorant alkylphenols and chlorophenols and their derivatives in water samples. The extraction conditions of HS-SPME were optimized including fiber selection, extraction temperature, extraction time, and salt concentration. Results showed that divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was the most appropriate one among the three selected commercial fibers, and the optimal extraction temperature, time, and salt concentration were 70 °C, 30 min, and 0.25 g/mL, respectively. The developed method was validated and showed good linearity (R (2) > 0.989), low limit of detection (LOD, 0.002-0.5 μg/L), and excellent recoveries (76-126 %) with low relative standard deviation (RSD, 0.7-12.9 %). The developed method was finally applied to two surface water samples and some of these target compounds were detected. All these detected compounds were below their odor thresholds, except for 2,4,6-TCAS and 2,4,6-TBAS wherein their concentrations were near their odor thresholds. However, in the two surface water samples, these detected compounds contributed to a certain amount of estrogenicity, which seemed to suggest that more attention should be paid to the issue of estrogenicity rather than to the odor problem.

Influence of multi-industrial activities on trace metal contamination: an approach towards surface water body in the vicinity of Dhaka Export Processing Zone (DEPZ).

PubMed

Ahmed, Golam; Miah, M Arzu; Anawar, Hossain M; Chowdhury, Didarul A; Ahmad, Jasim U

2012-07-01

Industrial wastewater discharged into aquatic ecosystems either directly or because of inadequate treatment of process water can increase the concentrations of pollutants such as toxic metals and others, and subsequently deteriorate water quality, environmental ecology and human health in the Dhaka Export Processing Zone (DEPZ), the largest industrial belt of 6-EPZ in Bangladesh. Therefore, in order to monitor the contamination levels, this study collected water samples from composite effluent points inside DEPZ and the surrounding surface water body connected to effluent disposal sites and determined the environmental hazards by chemical analysis and statistical approach. The water samples were analysed by inductively coupled plasma mass spectrometry to determine 12 trace metals such as As, Ag, Cr, Co, Cu, Li, Ni, Pb, Se, Sr, V and Zn in order to assess the influence of multi-industrial activities on metal concentrations. The composite effluents and surface waters from lagoons were characterized by a strong colour and high concentrations of biochemical oxygen demand, chemical oxygen demand, electrical conductivity, pH, total alkalinity, total hardness, total organic carbon, Turb., Cl(-), total suspended solids and total dissolved solids, which were above the limit of Bangladesh industrial effluent standards, but dissolved oxygen concentration was lower than the standard value. The measurement of skewness and kurtosis values showed asymmetric and abnormal distribution of the elements in the respective phases. The mean trend of variation was found in a decreasing order: Zn > Cu > Sr > Pb > Ni > Cr > Li > Co > V > Se > As > Ag in composite industrial effluents and Zn > Cu > Sr > Pb > Ni > Cr > Li > V > As > Ag > Co > Se in surface waters near the DEPZ. The strong correlations between effluent and surface water metal contents indicate that industrial wastewaters discharged from DEPZ have a strong influence on the contamination of the surrounding water bodies by toxic metals. The average contamination factors were reported to be 0.70-96.57 and 2.85-1,462 for industrial effluents and surface waters, respectively. The results reveal that the surface water in the area is highly contaminated with very high concentrations of some heavy/toxic metals like Zn, Pb, Cu, Ni and Cr; their average contamination factors are 1,460, 860, 136, 74.71 and 4.9, respectively. The concentrations of the metals in effluent and surface water were much higher than the permissible limits for drinking water and the world average concentrations in surface water. Therefore, the discharged effluent and surface water may create health hazards especially for people working and living inside and in the surrounding area of DEPZ.

Incorporating agricultural management into an earth system model for the Pacific Northwest region: Interactions between climate, hydrology, agriculture, and economics

NASA Astrophysics Data System (ADS)

Chinnayakanahalli, K.; Adam, J. C.; Stockle, C.; Nelson, R.; Brady, M.; Rajagopalan, K.; Barber, M. E.; Dinesh, S.; Malek, K.; Yorgey, G.; Kruger, C.; Marsh, T.; Yoder, J.

2011-12-01

For better management and decision making in the face of climate change, earth system models must explicitly account for natural resource and agricultural management activities. Including crop system, water management, and economic models into an earth system modeling framework can help in answering questions related to the impacts of climate change on irrigation water and crop productivity, how agricultural producers can adapt to anticipated climate change, and how agricultural practices can mitigate climate change. Herein we describe the coupling of the Variability Infiltration Capacity (VIC) land surface model, which solves the water and energy balances of the hydrologic cycle at regional scales, with a crop-growth model, CropSyst. This new model, VIC-CropSyst, is the land surface model that will be used in a new regional-scale model development project focused on the Pacific Northwest, termed BioEarth. Here we describe the VIC-CropSyst coupling process and its application over the Columbia River basin (CRB) using agricultural-specific land cover information. The Washington State Department of Agriculture (WSDA) and U. S. Department of Agriculture (USDA) cropland data layers were used to identify agricultural land use patterns, in which both irrigated and dry land crops were simulated. The VIC-CropSyst model was applied over the CRB for the historical period of 1976 - 2006 to establish a baseline for surface water availability, irrigation demand, and crop production. The model was then applied under future (2030s) climate change scenarios derived from statistically-downscaled Global Circulation Models output under two emission scenarios (A1B and B1). Differences between simulated future and historical irrigation demand, irrigation water availability, and crop production were used in an economics model to identify the most economically-viable future cropping pattern. The economics model was run under varying scenarios of regional growth, trade, water pricing, and water capacity providing a spectrum of possible future cropping patterns. The resulting cropping patterns were then used in VIC-CropSyst to quantify the impacts of climate change, economic, and water management scenarios on crop production, and water resources availability. This modeling framework provides opportunities to study the interactions between human activities and complex natural processes and is a valuable tool for inclusion in an earth system model with the goal of informing land use and water management.

Ocean to land moisture transport is reflected in sea surface salinity

NASA Astrophysics Data System (ADS)

Schmitt, R. W.; Schanze, J. J.; Li, L.; Ummenhofer, C.

2016-02-01

The ocean has a much larger water cycle than the land, with global ocean evaporation of 13 Sverdrups being 10 times larger than the sum of all river flows. This disparity and the different dynamics of dry surfaces, have led to an unfortunate disconnect between terrestrial hydrologists and oceanographers. Here we show that there is in fact a close coupling between the water cycles of ocean and land. In both cases there is much local recycling of moisture, since it does not travel far in the atmosphere. We argue that the most important water cycle variable is the net export (or import) of water from (to) an area. Over the open ocean this is just evaporation minus precipitation (E-P). The "P vs E" plot is a valuable tool for identifying the source and sink regions of the water cycle. The subtropical high pressure systems are the source regions of the water cycle, with a global net export of 4.5 Sv. The three sinks are the ITCZ in the tropics, the high latitude subpolar lows, and the land, all at about 1.5 Sv, though the subpolar lows do receive more water than the tropics, where high rainfall is maintained by much local recycling. Of course, the signature of E-P in the open ocean is the sea surface salinity (SSS), as only net freshwater fluxes can create salinity variations. With the land receiving 1/3 of the oceanic export, we should expect close coupling between terrestrial rainfall and the salinity of nearby oceans, and SSS variations have indeed been found to be valuable for seasonal rainfall forecasts on land. The remarkable 3-6 month lead of winter-spring SSS over summer rainfall appears to be mediated by the recycling process on land through soil moisture. When soil moisture is high, terrestrial regions can become more oceanic-like, with solar heating energizing evaporation and leading to down-stream propagation of the moisture signal (the "brown ocean" effect). The correlation of high SSS with high rainfall promises to be a very valuable seasonal prediction tool for a variety of regions around the world.

Method of bonding functional surface materials to substrates and applications in microtechnology and anti-fouling

DOEpatents

Feng, Xiangdong; Liu, Jun; Liang, Liang

2001-01-01

A simple and effective method to bond a thin coating of poly(N-isopropylacylamide) (NIPAAm) on a glass surface by UV photopolymerization, and the use of such a coated surface in nano and micro technology applications. A silane coupling agent with a dithiocarbamate group is provided as a photosensitizer preferably, (N,N'-diethylamine) dithiocarbamoylpropyl-(trimethoxy) silane (DATMS). The thiocarbamate group of the sensitizer is then bonded to the glass surface by coupling the silane agent with the hydroxyl groups on the glass surface. The modified surface is then exposed to a solution of NIPAAm and a crosslinking agent which may be any organic molecule having an acrylamide group and at least two double bonds in its structure, such as N, N'-methylenebisacrylamide, and a polar solvent which may be any polar liquid which will dissolve the monomer and the crosslinking agent such as acetone, water, ethanol, or combinations thereof. By exposing the glass surface to a UV light, free radicals are generated in the thiocarbamate group which then bonds to the crosslinking agent and the NIPAAm. Upon bonding, the crosslinking agent and the NIPAAm polymerize to form a thin coating of PNIPAAm bonded to the glass. Depending upon the particular configuration of the glass, the properties of the PNIPAAm allow applications in micro and nano technology.

Method of bonding functional surface materials to substrates and applications in microtechnology and antifouling

DOEpatents

Feng, Xiangdong; Liu, Jun; Liang, Liang

1999-01-01

A simple and effective method to bond a thin coating of poly(N-isopropylacylamide) (NIPAAm) on a glass surface by UV photopolymerization, and the use of such a coated surface in nano and micro technology applications. A silane coupling agent with a dithiocarbamate group is provided as a photosensitizer, preferably, (N,N'-diethylamine)dithiocarbamoylpropyl-(trimethoxy)silane (DATMS). The thiocarbamate group of the sensitizer is then bonded to the glass surface by coupling the silane agent with the hydroxyl groups on the glass surface. The modified surface is then exposed to a solution of NIPAAm and a crosslinking agent which may be any organic molecule having an acrylamide group and at least two double bonds in its structure, such as N,N'-methylenebisacrylamide, and a polar solvent which may be any polar liquid which will dissolve the monomer and the crosslinking agent such as acetone, water, ethanol, or combinations thereof. By exposing the glass surface to a UV light, free radicals are generated in the thiocarbamate group which then bonds to the crosslinking agent and the NIPAAm. Upon bonding, the crosslinking agent and the NIPAAm polymerize to form a thin coating of PNIPAAm bonded to the glass. Depending upon the particular configuration of the glass, the properties of the PNIPAAm allow applications in micro and nano technology.

Systematic Mapping and Statistical Analyses of Valley Landform and Vegetation Asymmetries Across Hydroclimatic Gradients

NASA Astrophysics Data System (ADS)

Poulos, M. J.; Pierce, J. L.; McNamara, J. P.; Flores, A. N.; Benner, S. G.

2015-12-01

Terrain aspect alters the spatial distribution of insolation across topography, driving eco-pedo-hydro-geomorphic feedbacks that can alter landform evolution and result in valley asymmetries for a suite of land surface characteristics (e.g. slope length and steepness, vegetation, soil properties, and drainage development). Asymmetric valleys serve as natural laboratories for studying how landscapes respond to climate perturbation. In the semi-arid montane granodioritic terrain of the Idaho batholith, Northern Rocky Mountains, USA, prior works indicate that reduced insolation on northern (pole-facing) aspects prolongs snow pack persistence, and is associated with thicker, finer-grained soils, that retain more water, prolong the growing season, support coniferous forest rather than sagebrush steppe ecosystems, stabilize slopes at steeper angles, and produce sparser drainage networks. We hypothesize that the primary drivers of valley asymmetry development are changes in the pedon-scale water-balance that coalesce to alter catchment-scale runoff and drainage development, and ultimately cause the divide between north and south-facing land surfaces to migrate northward. We explore this conceptual framework by coupling land surface analyses with statistical modeling to assess relationships and the relative importance of land surface characteristics. Throughout the Idaho batholith, we systematically mapped and tabulated various statistical measures of landforms, land cover, and hydroclimate within discrete valley segments (n=~10,000). We developed a random forest based statistical model to predict valley slope asymmetry based upon numerous measures (n>300) of landscape asymmetries. Preliminary results suggest that drainages are tightly coupled with hillslopes throughout the region, with drainage-network slope being one of the strongest predictors of land-surface-averaged slope asymmetry. When slope-related statistics are excluded, due to possible autocorrelation, valley slope asymmetry is most strongly predicted by asymmetries of insolation and drainage density, which generally supports a water-balance based conceptual model of valley asymmetry development. Surprisingly, vegetation asymmetries had relatively low predictive importance.

A preliminary assessment of water partitioning and ecohydrological coupling in northern headwaters using stable isotopes and conceptual runoff models

PubMed Central

Buttle, James; Carey, Sean K.; van Huijgevoort, Marjolein H. J.; Laudon, Hjalmar; McNamara, James P.; Mitchell, Carl P. J.; Spence, Chris; Gabor, Rachel S.; Soulsby, Chris

2015-01-01

Abstract We combined a conceptual rainfall‐runoff model and input–output relationships of stable isotopes to understand ecohydrological influences on hydrological partitioning in snow‐influenced northern catchments. Six sites in Sweden (Krycklan), Canada (Wolf Creek; Baker Creek; Dorset), Scotland (Girnock) and the USA (Dry Creek) span moisture and energy gradients found at high latitudes. A meta‐analysis was carried out using the Hydrologiska Byråns Vattenbalansavdelning (HBV) model to estimate the main storage changes characterizing annual water balances. Annual snowpack storage importance was ranked as Wolf Creek > Krycklan > Dorset > Baker Creek > Dry Creek > Girnock. The subsequent rate and longevity of melt were reflected in calibrated parameters that determine partitioning of waters between more rapid and slower flowpaths and associated variations in soil and groundwater storage. Variability of stream water isotopic composition depends on the following: (i) rate and duration of spring snowmelt; (ii) significance of summer/autumn rainfall; and (iii) relative importance of near‐surface and deeper flowpaths in routing water to the stream. Flowpath partitioning also regulates influences of summer evaporation on drainage waters. Deviations of isotope data from the Global Meteoric Water Line showed subtle effects of internal catchment processes on isotopic fractionation most likely through evaporation. Such effects are highly variable among sites and with seasonal differences at some sites. After accounting for climate, evaporative fractionation is strongest at sites where lakes and near‐surface runoff processes in wet riparian soils can mobilize isotopically enriched water during summer and autumn. Given close soil–vegetation coupling, this may result in spatial variability in soil water isotope pools available for plant uptake. We argue that stable isotope studies are crucial in addressing the many open questions on hydrological functioning of northern environments. © 2015 The Authors. Hydrological Processes published by John Wiley & Sons Ltd. PMID:27656040

Controls on Variations of Surface Energy, Water, and Carbon Budgets within Large-Scale Amazon Basin

NASA Technical Reports Server (NTRS)

Smith, Eric A.; Cooper, Harry J.; Grose, Andrew; Gu, Jiu-Jing; Norman, John; daRocha, Humberto R.; Dias, Pedro Silva

2002-01-01

A key research focus of the LBA Research Program is understanding the space-time variations in interlinked surface energy, water, and carbon budgets, the controls on these variations, and the implications of these controls on the carbon sequestering capacity of the large scale forest-pasture system that dominates the Amaz6nia landscape. Quantification of these variations and controls are investigated by a combination of in situ measurements, remotely sensed measurements from space, and a realistically forced hydrometeorological model coupled to a carbon assimilation model, capable of simulating details within the surface energy and water budgets along with the principle processes of photosynthesis and respiration. Herein we describe the results of an investigation concerning the space-time controls of carbon sources and sinks distributed over the large scale Amazon basin. The results are derived from a carbon-water-energy budget retrieval system for the large scale Amazon basin, which uses a coupled carbon assimilation-hydrometeorological model as an integrating system, forced by both in situ meteorological measurements and remotely sensed radiation and precipitation fluxes obtained from a combination of GOES, SSM/I, TOMS, and TRh4M satellite measurements. Results include validation of (a) retrieved surface radiation and precipitation fluxes based on 30-min averaged surface measurements taken at Ji-Parani in Rondania and Manaus in Amazonas, and (b) modeled sensible, latent, and C02 fluxes based on tower measurements taken at Reserva Jaru, Manaus and Fazenda Nossa Senhora. The space-time controls on carbon sequestration are partitioned into sets of factors classified by: (1) above canopy meteorology, (2) incoming surface radiation, (3) precipitation interception, and (4) indigenous stomatal processes varied over the different land covers of pristine rainforest, partially, and fully logged rainforests, and pasture lands. These are the principle meteorological, thermodynamical, hydrological, and biophysical control paths which perturb net carbon fluxes and sequestration, produce time-space switching of carbon sources and sinks, undergo modulation through atmospheric boundary layer feedbacks, and respond to any discontinuous intervention on the landscape itself such as produced by human intervention in converting rainforest to pasture or conducting selective/clearcut logging operations. The results demonstrate how relative carbon sequestration capacity of the Amazonian ecosystem responds to these controls, and how interpretation of space-time heterogeneities in carbon sequestration depends on a fairly exact quantification of the interacting non-linear properties of photosynthesis in response to incoming solar flux, air-canopy temperatures, and leaf water interception -- and soil respiration in response to upper layer soil temperature and water content. The results also show how the interpretation of the control processes is highly sensitive to the scales at which the surface fluxes are analyzed.

Rock failure analysis by combined thermal weakening and water jet impact

NASA Technical Reports Server (NTRS)

Nayfeh, A. H.

1976-01-01

The influence of preheating on the initiation of fracture in rocks subjected to the impingement of a continuous water jet is studied. Preheating the rock is assumed to degrade its mechanical properties and strength in accordance with existing experimental data. The water jet is assumed to place a quasi-static loading on the surface of the rock. The loading is approximated by elementary functions which permit analytic computation of the induced stresses in a rock half-space. The resulting stresses are subsequently coupled with the Griffith criteria for tensile failure to estimate the change, due to heating, in the critical stagnation pressure and velocity of the water jet required to cause failure in the rock.

Tensile properties and water absorption assessment of linear low-Density Polyethylene/Poly (Vinyl Alcohol)/Kenaf composites: effect of eco-friendly coupling agent

NASA Astrophysics Data System (ADS)

Pang, A. L.; Ismail, H.; Abu Bakar, A.

2018-02-01

Linear low-density polyethylene (LLDPE)/poly (vinyl alcohol) (PVOH) filled with untreated kenaf (UT-KNF) and eco-friendly coupling agent (ECA)-treated kenaf (ECAT-KNF) were prepared using ThermoHaake internal mixer, respectively. Filler loadings of UT-KNF and ECAT-KNF used in this study are 10 and 40 parts per hundred parts of resin (phr). The effect of ECA on tensile properties and water absorption of LLDPE/PVOH/KNF composites were investigated. Field emission scanning electron microscopy (FESEM) analysis was applied to visualize filler-matrix adhesion. The results indicate LLDPE/PVOH/ECAT-KNF composites possess higher tensile strength and tensile modulus, but lower elongation at break compared to LLDPE/PVOH/UT-KNF composites. The morphological studies of tensile fractured surfaces using FESEM support the increment in tensile properties of LLDPE/PVOH/ECAT-KNF composites. Nevertheless, LLDPE/PVOH/UT-KNF composites reveal higher water absorption compared to LLDPE/PVOH/ECAT-KNF composites.

Photoelectrochemical Performance of the Ag(III)-Based Oxygen-Evolving Catalyst.

PubMed

Sordello, Fabrizio; Ghibaudo, Manuel; Minero, Claudio

2017-07-19

We report the electrosynthesis of a water oxidation catalyst based on Ag oxides (AgCat). The deposited AgCat is composed of mixed valence crystalline Ag oxides with the presence of particle aggregates whose size is ∼1 μm. This catalyst, coupled with TiO 2 and hematite, and under photoelectrochemical conditions, substantially increases photocurrents in a wide range of applied potentials compared with bare and Co-Pi-modified photocatalysts. AgCat can sustain current densities comparable with other water oxidation catalysts. Dark bulk electrolysis demonstrated that AgCat is stable and can sustain high turnover number in operative conditions. Oxygen evolution from water occurs in mild conditions: pH = 2-13, room temperature and pressure, and moderate overpotentials (600 mV) compatible with the coupling with semiconducting oxides as sensitizers. Using hematite in sustained electrolysis O 2 production is significant, both in the dark and under irradiation, after an initial slow induction time in which modification of surface species occurs.

Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy.

PubMed

Guo, Jing; You, Sifan; Wang, Zhichang; Peng, Jinbo; Ma, Runze; Jiang, Ying

2018-05-27

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal structure and probing the hydrogen-bond (H-bond) dynamics of the water molecules adsorbed on solid surfaces are fundamental issues of water science, which remains a great challenge owing to the light mass and small size of hydrogen. Scanning tunneling microscopy (STM) is a promising tool for attacking these problems, thanks to its capabilities of sub-Ångström spatial resolution, single-bond vibrational sensitivity, and atomic/molecular manipulation. The designed experimental system consists of a Cl-terminated tip and a sample fabricated by dosing water molecules in situ onto the Au(111)-supported NaCl(001) surfaces. The insulating NaCl films electronically decouple the water from the metal substrates, so the intrinsic frontier orbitals of water molecules are preserved. The Cl-tip facilitates the manipulation of the single water molecules, as well as gating the orbitals of water to the proximity of Fermi level (EF) via tip-water coupling. This paper outlines the detailed methods of submolecular resolution imaging, molecular/atomic manipulation, and single-bond vibrational spectroscopy of interfacial water. These studies open up a new route for investigating the H-bonded systems at the atomic scale.

Effects of warming on groundwater flow in mountainous snowmelt-dominated catchments

NASA Astrophysics Data System (ADS)

Evans, S. G.; Ge, S.; Molotch, N. P.

2015-12-01

In mountainous regions, warmer air temperatures have led to an earlier onset of spring snowmelt and lower snowmelt rates; i.e. because snowmelt has shifted earlier when energy availability is lower. These changes to snowmelt will likely affect the partitioning of snowmelt water between surface runoff and groundwater flow, and therefore, the lag time between snowmelt and streamflow. While the connection between snowmelt and surface runoff has been well-studied, the impact of snowmelt variability on groundwater flow processes has received limited attention, especially in mountainous catchments. We construct a two-dimensional, finite element, coupled flow and heat transport hydrogeologic model to evaluate how changes in snowmelt onset and rate may alter groundwater discharge to streams in mountainous catchments. The coupled hydrogeologic model simulates seasonally frozen ground by incorporating permeability variation as a function of temperature and allows for modeling of pore water freeze and thaw. We apply the model to the Green Lakes Valley (GLV) watershed in the Rocky Mountains of Colorado, a representative snowmelt-dominated catchment. Snowmelt for the GLV catchment is reconstructed from a 12 year (1996-2007) dataset of hydrometeorological records and satellite-derived snow covered area. Modeling results suggest that on a yearly cycle, groundwater infiltration and discharge is limited by the seasonally frozen subsurface. Under average conditions from 1996 to 2007, maximum groundwater discharge to the surface lags maximum snowmelt by approximately two months. Ongoing modeling is exploring how increasing air temperatures affect lag times between snowmelt and groundwater discharge to streams. This study has implications for water resource availability and its temporal variability in a warming global climate.

A new multi-proxy reconstruction of Atlantic deep ocean circulation during the warm mid-Pliocene

NASA Astrophysics Data System (ADS)

Riesselman, C. R.; Dowsett, H. J.; Scher, H. D.; Robinson, M. M.

2011-12-01

The mid-Pliocene (3.264 - 3.025 Ma) is the most recent interval in Earth's history with sustained global temperatures in the range of warming predicted for the 21st century, providing an appealing analog with which to examine the Earth system changes we might encounter in the coming century. Ongoing sea surface and deep ocean temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm anomaly coupled with increased evaporation in the mid-Pliocene, possibly driving enhanced meridional overturning circulation and North Atlantic Deep Water production. However deep ocean temperature is not a conclusive proxy for water mass, and most coupled model simulations predict transient decreases in North Atlantic Deep Water production in 21st century, presenting a contrasting picture of future warmer worlds. Here, we present early results from a new multi-proxy reconstruction of Atlantic deep ocean circulation during the warm mid-Pliocene, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic imprint on fossil fish teeth as a proxy for water mass source region along a three-site depth transect from the Walvis Ridge (subtropical South Atlantic). The deep ocean circulation reconstructions resulting from this project will add a new dimension to the PRISM effort and will be useful for both initialization and evaluation of future model simulations.

The Role of Different Plant Soil-Water Feedbacks in Models of Dryland Vegetation Patterns

NASA Astrophysics Data System (ADS)

Silber, M.; Bonetti, S.; Gandhi, P.; Gowda, K.; Iams, S.; Porporato, A. M.

2017-12-01

Understanding the processes underlying the formation of regular vegetation patterns in arid and semi-arid regions is important to assessing desertification risk under increasing anthropogenic pressure. Various modeling frameworks have been proposed, which are all capable of generating similar patterns through self-organizing mechanisms that stem from assumptions about plant feedbacks on surface/subsurface water transport. We critically discuss a hierarchy of hydrology-vegetation models for the coupled dynamics of surface water, soil moisture, and vegetation biomass on a hillslope. We identify distinguishing features and trends for the periodic traveling wave solutions when there is an imposed idealized topography and make some comparisons to satellite images of large-scale banded vegetation patterns in drylands of Africa, Australia and North America. This work highlights the potential for constraining models by considerations of where the patterns may lie on a landscape, such as whether on a ridge or in a valley.

Response comment: Carbon sequestration on Mars

USGS Publications Warehouse

Edwards, Christopher; Ehlmann, Bethany L.

2016-01-01

Martian atmospheric pressure has important implications for the past and present habitability of the planet, including the timing and causes of environmental change. The ancient Martian surface is strewn with evidence for early water bound in minerals (e.g., Ehlmann and Edwards, 2014) and recorded in surface features such as large catastrophically created outflow channels (e.g., Carr, 1979), valley networks (Hynek et al., 2010; Irwin et al., 2005), and crater lakes (e.g., Fassett and Head, 2008). Using orbital spectral data sets coupled with geologic maps and a set of numerical spectral analysis models, Edwards and Ehlmann (2015) constrained the amount of atmospheric sequestration in early Martian rocks and found that the majority of this sequestration occurred prior to the formation of the early Hesperian/late Noachian valley networks (Fassett and Head, 2011; Hynek et al., 2010), thus implying the atmosphere was already thin by the time these surface-water-related features were formed.

MEDUSA (Martian Environmental DUst Systematic Analyser) for the monitoring of the Martian atmospheric dust and water vapour

NASA Astrophysics Data System (ADS)

Colangeli, L.; Battaglia, R.; della Corte, V.; Esposito, F.; Ferrini, G.; Mazzotta Epifani, E.; Palomba, E.; Palumbo, P.; Panizza, A.; Rotundi, A.

2004-03-01

The knowledge of Martian airborne dust properties and about mechanisms of dust settling/raising to/from the surface are important to determine climate and surface evolution on Mars. Water is an important tracer of climatic changes on long time-scales and is strictly related to the presence of life forms. The study in situ of dust and water vapour properties and evolution in Martian atmosphere is useful to trace back the planet climate, also in function of life form development. This investigation is also appropriate in preparation to future manned exploration of the planet (in relation to hazardous conditions). In this work we discuss the concept of the MEDUSA (Martian Environmental Dust Analyser) experiment that is designed to provide data on grain size and mass distribution, number density, velocity and scattering properties and on water vapour concentration. The instrument is a multisensor system based on optical and impact detection of grains, coupled with cumulative deposition sensors.

[Multi-Scale Convergence of Cold-Land Process Representation in Land-Surface Models, Microwave Remote Sensing, and Field Observations

NASA Technical Reports Server (NTRS)

Shi, Jiancheng

2005-01-01

The cryosphere is a major component of the hydrosphere and interacts significantly with the global climate system, the geosphere, and the biosphere. Measurement of the amount of water stored in the snow pack and forecasting the rate of melt are thus essential for managing water supply and flood control systems. Snow hydrologists are confronted with the dual problems of estimating both the quantity of water held by seasonal snow packs and time of snow melt. Monitoring these snow parameters is essential for one of the objectives of the Earth Science Enterprise-understanding of the global hydrologic cycle. Measuring spatially distributed snow properties, such as snow water equivalence (SWE) and wetness, from space is a key component for improvement of our understanding of coupled atmosphere-surface processes. Through the GWEC project, we have significantly advanced our understandings and improved modeling capabilities of the microwave signatures in response to snow and underground properties.

Bathymetry of Lake Manatee, Manatee County, Florida, 2009

USGS Publications Warehouse

Bellino, Jason C.; Pfeiffer, William R.

2010-01-01

Lake Manatee, located in central Manatee County, Florida, is the principal drinking-water source for Manatee and Sarasota Counties. The drainage basin of Lake Manatee encompasses about 120 square miles, and the reservoir covers a surface area of about 1,450 acres at an elevation of 38.8 feet above NAVD 88 or 39.7 feet above NGVD 29. The full pool water-surface elevation is 39.1 feet above NAVD 88 (40.0 feet above NGVD 29), and the estimated minimum usable elevation is 25.1 feet above NAVD 88 (26.0 feet above NGVD 29). The minimum usable elevation is based on the elevation of water intake structures. Manatee County has used the stage/volume relation that was developed from the original survey in the 1960s to estimate the volume of water available for consumption. Concerns about potential changes in storage capacity of the Lake Manatee reservoir, coupled with a recent drought, led to this bathymetry mapping effort.

Landslide Hazard from Coupled Inherent and Dynamic Probabilities

NASA Astrophysics Data System (ADS)

Strauch, R. L.; Istanbulluoglu, E.; Nudurupati, S. S.

2015-12-01

Landslide hazard research has typically been conducted independently from hydroclimate research. We sought to unify these two lines of research to provide regional scale landslide hazard information for risk assessments and resource management decision-making. Our approach couples an empirical inherent landslide probability, based on a frequency ratio analysis, with a numerical dynamic probability, generated by combining subsurface water recharge and surface runoff from the Variable Infiltration Capacity (VIC) macro-scale land surface hydrologic model with a finer resolution probabilistic slope stability model. Landslide hazard mapping is advanced by combining static and dynamic models of stability into a probabilistic measure of geohazard prediction in both space and time. This work will aid resource management decision-making in current and future landscape and climatic conditions. The approach is applied as a case study in North Cascade National Park Complex in northern Washington State.

Computational Study of Interstellar Glycine Formation Occurring at Radical Surfaces of Water-ice Dust Particles

NASA Astrophysics Data System (ADS)

Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero

2012-07-01

Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH• radical and H3O+ surface defects. The coupling of incoming CO molecules with the surface OH• radicals on the ice clusters yields the formation of the COOH• radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol-1 and -22 kcal mol-1, respectively. The COOH• radicals couple with incoming NH=CH2 molecules (experimentally detected in the ISM) to form the NHCH2COOH• radical glycine through energy barriers of 12 kcal mol-1, exceedingly high at ISM cryogenic temperatures. Nonetheless, when H3O+ is present, one proton may be barrierless transferred to NH=CH2 to give NH2=CH2 +. This latter may react with the COOH• radical to give the NH2CH2COOH+• glycine radical cation which can then be transformed into the NH2CHC(OH)2 +• species (the most stable form of glycine in its radical cation state) or into the NH2CHCOOH• neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H3O+ ions to facilitate chemical processes by proton transfer (i.e., acting as acidic catalysts) is highlighted, and plausible ways of their formation at the water-ice surface in the ISM are also discussed.

CAUSES: Diagnosis of the Summertime Warm Bias in CMIP5 Climate Models at the ARM Southern Great Plains Site

NASA Astrophysics Data System (ADS)

Zhang, Chengzhu; Xie, Shaocheng; Klein, Stephen A.; Ma, Hsi-yen; Tang, Shuaiqi; Van Weverberg, Kwinten; Morcrette, Cyril J.; Petch, Jon

2018-03-01

All the weather and climate models participating in the Clouds Above the United States and Errors at the Surface project show a summertime surface air temperature (T2 m) warm bias in the region of the central United States. To understand the warm bias in long-term climate simulations, we assess the Atmospheric Model Intercomparison Project simulations from the Coupled Model Intercomparison Project Phase 5, with long-term observations mainly from the Atmospheric Radiation Measurement program Southern Great Plains site. Quantities related to the surface energy and water budget, and large-scale circulation are analyzed to identify possible factors and plausible links involved in the warm bias. The systematic warm season bias is characterized by an overestimation of T2 m and underestimation of surface humidity, precipitation, and precipitable water. Accompanying the warm bias is an overestimation of absorbed solar radiation at the surface, which is due to a combination of insufficient cloud reflection and clear-sky shortwave absorption by water vapor and an underestimation in surface albedo. The bias in cloud is shown to contribute most to the radiation bias. The surface layer soil moisture impacts T2 m through its control on evaporative fraction. The error in evaporative fraction is another important contributor to T2 m. Similar sources of error are found in hindcast from other Clouds Above the United States and Errors at the Surface studies. In Atmospheric Model Intercomparison Project simulations, biases in meridional wind velocity associated with the low-level jet and the 500 hPa vertical velocity may also relate to T2 m bias through their control on the surface energy and water budget.

Direct and sensitive determination of glyphosate and aminomethylphosphonic acid in environmental water samples by high performance liquid chromatography coupled to electrospray tandem mass spectrometry.

PubMed

Guo, Hongyue; Riter, Leah S; Wujcik, Chad E; Armstrong, Daniel W

2016-04-22

A novel method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed for the sensitive determination of glyphosate and its major degradation product, AMPA in environmental water samples. The method involves the use of MS compatible mobile phases (0.1% formic acid in water and acetonitrile) for HPLC and direct analysis of water samples without sample derivatization. The method has been validated in different types of water matrices (drinking, surface and groundwater) by accuracy and precision studies with samples spiked at 0.1, 7.5 and 90 ppb. All mean accuracy values ranged from 85% to 112% for glyphosate and AMPA using both primary and secondary quantitative ion transitions (RSD ≤ 10%). Moreover, both primary and secondary ion transitions for glyphosate and AMPA can achieve the quantitation limits at 0.1 ppb. The linear dynamic range of the calibration curves were from 0.1 to 100 ppb for each analyte at each ion transitions with correlation coefficient higher than 0.997. Copyright © 2016 Elsevier B.V. All rights reserved.