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1

Runoff simulation in the Ferghana Valley (Central Asia) using conceptual hydrological HBV-light model  

NASA Astrophysics Data System (ADS)

Glaciers and permafrost on the ranges of the Tien Shan mountain system are primary sources of water in the Ferghana Valley. The water artery of the valley is the Syr Darya River that is formed by confluence of the Naryn and Kara Darya rivers, which originate from the mountain glaciers of the Ak-Shyrak and the Ferghana ranges accordingly. The Ferghana Valley is densely populated and main activity of population is agriculture that heavily depends on irrigation especially in such arid region. The runoff reduction is projected in future due to global temperature rise and glacier shrinkage as a consequence. Therefore, it is essential to study climate change impact on water resources in the area both for ecological and economic aspects. The evaluation of comparative contribution of small upper catchments (n=24) with precipitation predominance in discharge and the large Naryn and Karadarya River basins, which are fed by glacial melt water, to the Fergana Valley water balance under current and future climatic conditions is general aim of the study. Appropriate understanding of the hydrological cycle under current climatic conditions is significant for prognosis of water resource availability in the future. Thus, conceptual hydrological HBV-light model was used for analysing of the water balance of the small upper catchments that surround the Ferghana Valley. Three trial catchments (the Kugart River basin, 1010 km²; the Kurshab River basin, 2010 km2; the Akbura River basin, 2260 km²) with relatively good temporal quality data were chosen to setup the model. Due to limitation of daily temperature data the MODAWEC weather generator, which converts monthly temperature data into daily based on correlation with rainfall, was tested and applied for the HBV-light model.

Radchenko, Iuliia; Breuer, Lutz; Forkutsa, Irina; Frede, Hans-Georg

2013-04-01

2

Testing of a coupled model of the HBV model and a glacier retreat model on a Himalayan basin  

NASA Astrophysics Data System (ADS)

The Himalayan glaciers are source of numerous large Asian river systems, including the Indus, Ganges, and Brahmaputra, which provide water for 1.5 billion people. This region is among areas that are the most sensitive to climate change. Shrinking of the glaciers is expected to significantly affect hydrologic responses of glaciated basins. Retreat of glaciers in these basins is predicted to cause severe water crisis in these basins. However, glacier behaviours are not well represented in most current hydrological models. The objective of the present study is to test performance of a coupled model consisting of a hydrological model and a glacier retreat model. The hydrological model is a distributed HBV model, simulating runoff response to water input into catchment. The glacier retreat model is a distributed glacier-specific model, ?h-parameterization describing ice redistribution caused by glacier movement. The Beas River basin in the Northern India is selected as focus area because of its high representativeness of the Himalayan basins and availability of data. This study will not only improve the HBV model for hydrological studies in glaciated catchments, but also contribute to improved understanding and modelling of glacier hydrology. The coupled model will be a useful tool for water resources projections and hydropower planning in a far future on highly glaciated basins.

LI, Hong; Xu, Chongyu; Beldring, Stein; Melvold, Kjetil; Jain, Sharad

2014-05-01

3

Solicited abstract: Global hydrological modeling and models  

NASA Astrophysics Data System (ADS)

The origins of rainfall-runoff modeling in the broad sense can be found in the middle of the 19th century arising in response to three types of engineering problems: (1) urban sewer design, (2) land reclamation drainage systems design, and (3) reservoir spillway design. Since then numerous empirical, conceptual and physically-based models are developed including event based models using unit hydrograph concept, Nash's linear reservoir models, HBV model, TOPMODEL, SHE model, etc. From the late 1980s, the evolution of global and continental-scale hydrology has placed new demands on hydrologic modellers. The macro-scale hydrological (global and regional scale) models were developed on the basis of the following motivations (Arenll, 1999). First, for a variety of operational and planning purposes, water resource managers responsible for large regions need to estimate the spatial variability of resources over large areas, at a spatial resolution finer than can be provided by observed data alone. Second, hydrologists and water managers are interested in the effects of land-use and climate variability and change over a large geographic domain. Third, there is an increasing need of using hydrologic models as a base to estimate point and non-point sources of pollution loading to streams. Fourth, hydrologists and atmospheric modellers have perceived weaknesses in the representation of hydrological processes in regional and global climate models, and developed global hydrological models to overcome the weaknesses of global climate models. Considerable progress in the development and application of global hydrological models has been achieved to date, however, large uncertainties still exist considering the model structure including large scale flow routing, parameterization, input data, etc. This presentation will focus on the global hydrological models, and the discussion includes (1) types of global hydrological models, (2) procedure of global hydrological model development, (3) state-of-the-art of existing global hydrological models, and (4) challenges. Acknowledgment: Thanks to Lebing Gong, Elin Widén-Nilsson, and Sven Halldin of Uppsala University for the team work in global hydrological models.

Xu, Chong-Yu

2010-05-01

4

Assimilating H-SAF and MODIS Snow Cover Data into the Conceptual Models HBV and SRM  

NASA Astrophysics Data System (ADS)

Conceptual hydrological models are widely used for operational and scientific water resources management applications in mountain catchments. However, current model-based forecasting approaches are jeopardized by input data and model uncertainties. Data assimilation provides a suitable tool to merge information from remotely sensed observations and hydrological model predictions for improving the lead time performance of streamflow forecasts in the context of operational hydrological forecasting systems. In this study, we present a novel variational approach based on Moving Horizon Estimation (MHE). It includes a highly flexible formulation of distance metrics for penalizing the introduction of noise into the model and enforcing the agreement between simulated and observed variables. Furthermore, the MHE setup shows a high robustness regarding non-equidistant, noisy and sometimes missing data and enables the modification of model input as well as state variables. In situ snowpack measurements are sparsely distributed in mountainous regions. Therefore the data limitations in combination with snowpack heterogeneity prevent a detailed understanding of the variability of snow cover and melt. Remotely sensed images offer an opportunity to supplement ground measurements for performing runoff predictions during the snowmelt season. In this context, EUMETSAT initiated the H-SAF (Satellite Application Facility on Support to Operational Hydrology and Water Management) project for deriving novel products from satellite data and applying it to operational hydrology. This research contributes to the H-SAF product validation by applying a generic data assimilation test bed for H-SAF snow products in comparison to snow cover data of MODIS. A preliminary performance assessment of the data assimilation framework using the conceptual models HBV and SRM with satellite derived snow data is evaluated for a snow dominated test site of 10250 km2 at the headwaters of Euphrates River in Turkey.

Sensoy, Aynur; Schwanenberg, Dirk; Sorman, Arda; Akkol, Bulut; Alvarado Montero, Rodolfo; Uysal, Gokcen

2014-05-01

5

A comparison of SRM and HBV models for real time runoff forecasting in the Upper Euphrates Basin, Turkey  

NASA Astrophysics Data System (ADS)

Predicting snowmelt runoff in the mountainous eastern part of Turkey at a daily time step is important in water resource management as it constitutes nearly 2/3 in volume of the total yearly runoff during spring and early summer months. Keeping track of snow dynamics as well as forecasting the amount and timing of snowmelt runoff in the headwaters of the trans-boundary Euphrates River, where large dams are located, is a crucial and challenging task concerning the practical importance and great demand for real time forecasting of melt water. In mountainous regions, data limitations prevent detailed understanding of the variability of snow cover and melt. In situ snowpack measurements are sparsely distributed relative to snowpack heterogeneity therefore, to supplement ground measurement networks, remotely sensed images of snow covered area (SCA) provide useful information for runoff prediction during the snowmelt season. SCA has been used as a direct input to hydrological models such as Snowmelt Runoff Model (SRM) or as a means of assimilating hydrologic model snowpack and checking the internal validity as in the case of HBV model. Alternative ways of handling melt water modeling using satellite derived SCA is discussed, with emphasis on the contrasting treatments in two widely used hydrologic models, SRM and HBV. The greatest similarity between the two models is that each uses a temperature index method to predict melt rate whereas the greatest difference lies in the way snow cover is handled. Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow cover products with 500 m spatial resolution are used to derive SCA data in this study. Since the cloud obscuring problem degrades the use of satellites with optical sensors, a special combination and filtering methodology is utilized to reduce cloud coverage of the product. Both models are used to simulate runoff for the years 2001-2010 with model efficiency above 0.86 and volume difference less than 2.5%. Finally, operational snowmelt runoff forecasting is carried out for 2011 ablation season using numerical weather prediction (Mesoscale Model 5) data as forcing input variables. Discussion of results are supervised to reflect the general debates in hydrologic modeling in terms of parameters and calibration, internal validation, the value and limitations of using satellite derived and numerical weather prediction data. Key words: snow, SRM, HBV, forecasting, Upper Euphrates Basin

Sorman, A. A.; Sensoy, A.; Yamankurt, E.; Gozel, E.

2012-04-01

6

Hydrological models are mediating models  

NASA Astrophysics Data System (ADS)

Despite the increasing role of models in hydrological research and decision-making processes, only few accounts of the nature and function of models exist in hydrology. Earlier considerations have traditionally been conducted while making a clear distinction between physically-based and conceptual models. A new philosophical account, primarily based on the fields of physics and economics, transcends classes of models and scientific disciplines by considering models as "mediators" between theory and observations. The core of this approach lies in identifying models as (1) being only partially dependent on theory and observations, (2) integrating non-deductive elements in their construction, and (3) carrying the role of instruments of scientific enquiry about both theory and the world. The applicability of this approach to hydrology is evaluated in the present article. Three widely used hydrological models, each showing a different degree of apparent physicality, are confronted to the main characteristics of the "mediating models" concept. We argue that irrespective of their kind, hydrological models depend on both theory and observations, rather than merely on one of these two domains. Their construction is additionally involving a large number of miscellaneous, external ingredients, such as past experiences, model objectives, knowledge and preferences of the modeller, as well as hardware and software resources. We show that hydrological models convey the role of instruments in scientific practice by mediating between theory and the world. It results from these considerations that the traditional distinction between physically-based and conceptual models is necessarily too simplistic and refers at best to the stage at which theory and observations are steering model construction. The large variety of ingredients involved in model construction would deserve closer attention, for being rarely explicitly presented in peer-reviewed literature. We believe that devoting more importance to identifying and communicating on the many factors involved in model development might increase transparency of model building.

Babel, L. V.; Karssenberg, D.

2013-08-01

7

Thermal-hydrological models  

SciTech Connect

This chapter describes the physical processes and natural and engineered system conditions that affect thermal-hydrological (T-H) behavior in the unsaturated zone (UZ) at Yucca Mountain and how these effects are represented in mathematical and numerical models that are used to predict T-H conditions in the near field, altered zone, and engineered barrier system (EBS), and on waste package (WP) surfaces.

Buscheck, T., LLNL

1998-04-29

8

Play with hydrologic models in R  

NASA Astrophysics Data System (ADS)

The aim of this poster is to show the advantages of building hydrologic models using the R environment for educational purposes. As an example we consider a conceptual rainfall-runoff model (HBV type) that was originally written in the fortran language and is used in many scientific studies and practical engineering applications in Austria. A simplified version of the model was built into a R package and compiled for different platforms and operating systems. The model runs on a daily time step and consists of a snow routine, a soil moisture routine and a flow routing routine. In this poster we present a set of examples that have been used in a graduate level course on engineering hydrology at the Vienna University of Technology. These include: - Multi-objective calibration of the model; - Manual vs. automatic calibration; - Visualisation of model outputs and efficiency; - Model application in ungauged catchments; - Operational forecast. The flexibility of R is ideal for education, since students can easily play with the extensive list of existing functionalities and define new functions and extensions.

Viglione, A.; Parajka, J.; Nester, T.; Blöschl, G.

2012-04-01

9

PATHS groundwater hydrologic model  

SciTech Connect

A preliminary evaluation capability for two-dimensional groundwater pollution problems was developed as part of the Transport Modeling Task for the Waste Isolation Safety Assessment Program (WISAP). Our approach was to use the data limitations as a guide in setting the level of modeling detail. PATHS Groundwater Hydrologic Model is the first level (simplest) idealized hybrid analytical/numerical model for two-dimensional, saturated groundwater flow and single component transport; homogeneous geology. This document consists of the description of the PATHS groundwater hydrologic model. The preliminary evaluation capability prepared for WISAP, including the enhancements that were made because of the authors' experience using the earlier capability is described. Appendixes A through D supplement the report as follows: complete derivations of the background equations are provided in Appendix A. Appendix B is a comprehensive set of instructions for users of PATHS. It is written for users who have little or no experience with computers. Appendix C is for the programmer. It contains information on how input parameters are passed between programs in the system. It also contains program listings and test case listing. Appendix D is a definition of terms.

Nelson, R.W.; Schur, J.A.

1980-04-01

10

Mathematical Modeling of Watershed Hydrology  

Microsoft Academic Search

Mathematical modeling of watershed hydrology is employed to address a wide spectrum of environmental and water re- sources problems. A historical perspective of hydrologic modeling is provided, and new developments and challenges in watershed models are discussed. These include data acquisition by remote sensing and space technology, digital terrain and elevation models, chemical tracers, geographic information and data management systems,

Vijay P. Singh

2002-01-01

11

Teaching hydrological modeling with a user-friendly catchment-runoff-model software package  

NASA Astrophysics Data System (ADS)

Computer models, and especially conceptual models, are frequently used for catchment hydrology studies. Teaching hydrological modeling, however, is challenging as students, when learning to apply computer models, have both to understand general model concepts and to be able to use particular computer programs. Here we present a new version of the HBV model. This software provides a user-friendly version which is especially useful for education. Different functionalities like an automatic calibration using a genetic algorithm or a Monte Carlo approach as well as the possibility to perform batch runs with predefined model parameters make the software also interesting for teaching in more advanced classes and research projects. Different teaching goals related to hydrological modeling are discussed and a series of exercises is suggested to reach these goals.

Seibert, J.; Vis, M. J. P.

2012-05-01

12

Teaching hydrological modeling with a user-friendly catchment-runoff-model software package  

NASA Astrophysics Data System (ADS)

Computer models, especially conceptual models, are frequently used for catchment hydrology studies. Teaching hydrological modeling, however, is challenging, since students have to both understand general model concepts and be able to use particular computer programs when learning to apply computer models. Here we present a new version of the HBV (Hydrologiska Byråns Vattenavdelning) model. This software provides a user-friendly version that is especially useful for education. Different functionalities, such as an automatic calibration using a genetic algorithm or a Monte Carlo approach, as well as the possibility to perform batch runs with predefined model parameters make the software interesting especially for teaching in more advanced classes and research projects. Different teaching goals related to hydrological modeling are discussed and a series of exercises is suggested to reach these goals.

Seibert, J.; Vis, M. J. P.

2012-09-01

13

Teaching hydrological modelling as a subsidiary subject  

Microsoft Academic Search

The department of hydrology and water resources management is part of the Ecology Center of Kiel University, an interdisciplinary research organization. We teach hydrology for geographers, biologists, agricultural engineers and ecologists. Hydrological modeling is part of the curriculum since 1988. It has moved from the subject for specialists to a basic component of all hydrological courses. During the first year,

G. Hörmann; B. Schmalz; N. Fohrer

2009-01-01

14

Weather Radar and Hydrology 1 Influence of rainfall spatial variability on hydrological modelling: a  

E-print Network

Weather Radar and Hydrology 1 Influence of rainfall spatial variability on hydrological modelling variability as well as characteristics and hydrological behavior of catchments, we have proceeded simulator and a distributed hydrological model (with four production functions and a distributed transfer

Paris-Sud XI, Université de

15

Exploring the effect of spatial disaggregation of conceptual hydrologic models for improved flow forecasting  

NASA Astrophysics Data System (ADS)

The availability of gridded climatic data, high resolution Digital Elevation Maps (DEM), soil, land-use and land-cover data has motivated researchers to exploit these data for more accurate distributed hydrologic modeling. However, with increased disaggregation there is the introduction of numerous parameters and conceptualized processes that are unobservable. In this study we explore the advantage of employing spatially distributed climatic and geographic information in the context of a disaggregated conceptual hydrologic modeling framework by developing distributed model versions for three hydrologic models: HYMOD (Hydrologic Model), HBV (Hydrologiska Byrans Vattenbalansavdelning), and SAC-SMA (Sacramento Soil Moisture Accounting). This study proposes a general framework for building a distributed conceptual hydrological model by coupling a rainfall-runoff model to a routing model which is based on the formularized sub-basin unit hydrograph and the linearized Saint-Venant equation. To deal with a very large number of model parameters resulting from the distributed system modeling approach, hydrological similarity and landscape classification derived from the geospatial database is used to reduce the complexity in the process of model parameter estimation. Tests for the Iowa River basin show that three distributed models outperform lumped model versions in terms of reproducing observed streamflow for both calibration and validation periods. Model calibration strategies informed by geospatial information yield flow predictions comparable to the fully distributed model simulations. Results from this study are encouraging and indicate that the proposed framework holds promise for making improved predictions of hydrologic system response.

Wi, S.; Brown, C. M.

2013-12-01

16

Evaluation of Optimization Methods for Hydrologic Model Calibration in Ontario Basins  

NASA Astrophysics Data System (ADS)

Particle Swarm Optimization algorithm (PSO), Shuffled Complex Evolution algorithm (SCE), Non-Dominated Sorted Genetic algorithm II (NSGA II) and a Monte Carlo procedure are applied to optimize the calibration of two conceptual hydrologic models namely the Sacramento Soil Moisture Accounting (SAC-SMA) and McMaster University-Hydrologiska Byråns Vattenbalansavdelning (MAC-HBV). PSO, SCE, and NSGA II are inherently evolutionary computational methods with a potential of reaching the global optimum in contrast to stochastic search algorithms such as Monte Carlo method. The spatial analysis maps of Nash Sutcliffe Efficiency (NSE) for daily streamflow and Volume Error (VE) for peak and low flows demonstrate that for both MAC-HBV and SAC-SMA, PSO and SCE are equally superior to NSGAII and Monte Carlo for all the selected 90 basins across Ontario (Canada) using 20 years (1976-1994) of hydrologic records. For peakflows, MAC-HBV with PSO has generally better performance compared to SCE, whereas SAC-SMA with SCE and PSO indicate similar performance. For low flows, MAC-HBV with PSO has a better performance for most of the northern large watersheds while SCE has a better performance for southern small watersheds. Temporal variability of NSE values for daily streamflow show that all the optimization methods perform better for the winter season compared to the summer.

Razavi, T.; Coulibaly, P. D.

2013-12-01

17

Model Discrepancy in the Saturated Path Hydrology Model: Initial Analysis  

E-print Network

Model Discrepancy in the Saturated Path Hydrology Model: Initial Analysis Tom Fricker University discrepancy in the Saturated Path Hydrology Model (logSPM, Kuczera et al., 2006). The purpose). 1 #12;3 The Saturated Path Hydrology Model We consider the Saturated Path Hydrology Model (log

Oakley, Jeremy

18

Committee of machine learning predictors of hydrological models uncertainty  

NASA Astrophysics Data System (ADS)

In prediction of uncertainty based on machine learning methods, the results of various sampling schemes namely, Monte Carlo sampling (MCS), generalized likelihood uncertainty estimation (GLUE), Markov chain Monte Carlo (MCMC), shuffled complex evolution metropolis algorithm (SCEMUA), differential evolution adaptive metropolis (DREAM), particle swarm optimization (PSO) and adaptive cluster covering (ACCO)[1] used to build a predictive models. These models predict the uncertainty (quantiles of pdf) of a deterministic output from hydrological model [2]. Inputs to these models are the specially identified representative variables (past events precipitation and flows). The trained machine learning models are then employed to predict the model output uncertainty which is specific for the new input data. For each sampling scheme three machine learning methods namely, artificial neural networks, model tree, locally weighted regression are applied to predict output uncertainties. The problem here is that different sampling algorithms result in different data sets used to train different machine learning models which leads to several models (21 predictive uncertainty models). There is no clear evidence which model is the best since there is no basis for comparison. A solution could be to form a committee of all models and to sue a dynamic averaging scheme to generate the final output [3]. This approach is applied to estimate uncertainty of streamflows simulation from a conceptual hydrological model HBV in the Nzoia catchment in Kenya. [1] N. Kayastha, D. L. Shrestha and D. P. Solomatine. Experiments with several methods of parameter uncertainty estimation in hydrological modeling. Proc. 9th Intern. Conf. on Hydroinformatics, Tianjin, China, September 2010. [2] D. L. Shrestha, N. Kayastha, and D. P. Solomatine, and R. Price. Encapsulation of parameteric uncertainty statistics by various predictive machine learning models: MLUE method, Journal of Hydroinformatic, in press, 2013. [3] N., Kayastha, J. Ye, F. Fenicia, V. Kuzmin, and D. P. Solomatine. Fuzzy committees of specialized rainfall-runoff models: further enhancements and tests. Hydrol. Earth Syst. Sci., 17, 4441-4451, 2013

Kayastha, Nagendra; Solomatine, Dimitri

2014-05-01

19

Remote sensing applications to hydrologic modeling  

NASA Technical Reports Server (NTRS)

An energy balance snowmelt model for rugged terrain was devised and coupled to a flow model. A literature review of remote sensing applications to hydrologic modeling was included along with a software development outline.

Dozier, J.; Estes, J. E.; Simonett, D. S.; Davis, R.; Frew, J.; Marks, D.; Schiffman, K.; Souza, M.; Witebsky, E.

1977-01-01

20

Hydrologic Modeling of Boreal Forest Ecosystems  

NASA Technical Reports Server (NTRS)

This study focused on the hydrologic response, including vegetation water use, of two test regions within the Boreal-Ecosystem-Atmosphere Study (BOREAS) region in the Canadian boreal forest, one north of Prince Albert, Saskatchewan, and the other near Thompson, Manitoba. Fluxes of moisture and heat were studied using a spatially distributed hydrology soil-vegetation-model (DHSVM).

Haddeland, I.; Lettenmaier, D. P.

1995-01-01

21

Snow hydrology in a general circulation model  

SciTech Connect

A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included. A 3-year GCM simulation with this more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow, hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere. 52 refs., 13 figs., 5 tabs.

Marshall, S. (Colorado State Univ., Fort Collins, CO (United States)); Roads, J.O. (Univ. of California, San Diego, CA (United States)); Glatzmaier, G. (Los Alamos National Lab., NM (United States))

1994-08-01

22

Snow hydrology in a general circulation model  

NASA Technical Reports Server (NTRS)

A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included by a specified snow line. A 3-year GCM simulation with this now more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere.

Marshall, Susan; Roads, John O.; Glatzmaier, Gary

1994-01-01

23

Hydrological model selection: A Bayesian alternative  

NASA Astrophysics Data System (ADS)

The evaluation and comparison of hydrological models has long been a challenge to the practicing hydrological community. No single model can be identified as ideal over the range of possible hydrological situations. With the variety of models available, hydrologic modelers are faced with the problem of determining which model is best applied to a catchment for a particular modeling exercise. The model selection problem is well documented in hydrologic studies, but a broadly applicable as well as theoretically and practically sound method for comparing model performance does not exist in the literature. Bayesian statistical inference, with computations carried out via Markov chain Monte Carlo (MCMC) methods, offers an attractive alternative to conventional model selection methods allowing for the combination of any preexisting knowledge about individual models and their respective parameters with the available catchment data to assess both parameter and model uncertainty. The aim of this study is to present a method by which hydrological models may be compared in a Bayesian framework. The study builds on previous work (Marshall et al., 2004) in which a Bayesian approach implemented using MCMC algorithms was presented as a simple and efficient basis for assessing parameter uncertainty in hydrological models. In this study, a model selection framework is developed in which an adaptive Metropolis algorithm is used to calculate the model's posterior odds. The model used to illustrate our approach is a version of the Australian Water Balance Model (Boughton, 1993) reformulated such that it can have a flexible number of soil moisture storages. To assess the model selection method in a controlled setting, artificial runoff data were created corresponding to a known model configuration. These data were used to evaluate the accuracy of the model selection method and its sensitivity to the size of the sample being used. An application of the Bayesian model identification methodology to 11 years of daily streamflow data from the Murrumbidgee River at Mittagang Crossing in southeastern Australia concludes our study.

Marshall, Lucy; Nott, David; Sharma, Ashish

2005-10-01

24

Covariance Models for Hydrological Applications  

NASA Astrophysics Data System (ADS)

This methodological contribution aims to present some new covariance models with applications in the stochastic analysis of hydrological processes. More specifically, we present explicit expressions for radially symmetric, non-differentiable, Spartan covariance functions in one, two, and three dimensions. The Spartan covariance parameters include a characteristic length, an amplitude coefficient, and a rigidity coefficient which determines the shape of the covariance function. Different expressions are obtained depending on the value of the rigidity coefficient and the dimensionality. If the value of the rigidity coefficient is much larger than one, the Spartan covariance function exhibits multiscaling. Spartan covariance models are more flexible than the classical geostatatistical models (e.g., spherical, exponential). Their non-differentiability makes them suitable for modelling the properties of geological media. We also present a family of radially symmetric, infinitely differentiable Bessel-Lommel covariance functions which are valid in any dimension. These models involve combinations of Bessel and Lommel functions. They provide a generalization of the J-Bessel covariance function, and they can be used to model smooth processes with an oscillatory decay of correlations. We discuss the dependence of the integral range of the Spartan and Bessel-Lommel covariance functions on the parameters. We point out that the dependence is not uniquely specified by the characteristic length, unlike the classical geostatistical models. Finally, we define and discuss the use of the generalized spectrum for characterizing different correlation length scales; the spectrum is defined in terms of an exponent ?. We show that the spectrum values obtained for exponent values less than one can be used to discriminate between mean-square continuous but non-differentiable random fields. References [1] D. T. Hristopulos and S. Elogne, 2007. Analytic properties and covariance functions of a new class of generalized Gibbs random fields, IEEE Transactions on Information Theory, 53(12), 4667 - 4679. [2] D. T. Hristopulos and M. Zukovic, 2011. Relationships between correlation lengths and integral scales for covariance models with more than two parameters, Stochastic Environmental Research and Risk Assessment, 25(1), 11-19. [3] D. T. Hristopulos, 2014. Radial Covariance Functions Motivated by Spatial Random Field Models with Local Interactions, arXiv:1401.2823 [math.ST] .

Hristopulos, Dionissios

2014-05-01

25

ARMA Model identification of hydrologic time series  

Microsoft Academic Search

In recent years, ARMA models have become popular for modeling geophysical time series in general and hydrologic time series in particular. The identification of the appropriate order of the model is an important stage in ARMA modeling. Such model identification is generally based on the autocorrelation and partial autocorrelation functions, although recently improvements have been obtained using the inverse autocorrelation

J. D. Salas; J. T. B. Obeysekera

1982-01-01

26

High-resolution, multi-scale modeling of watershed hydrology  

E-print Network

High-resolution, multi-scale modeling of watershed hydrology CUAHSI Cyber Seminar October 3, 2003 and Distributed Modeling in a Hydrologic Observatory Assistant Professor of Hydrology Department of Earth and Environmental Science New Mexico Institute of Mining and Technology #12;2 Real and Virtual Hydrologic

Vivoni, Enrique R.

27

On the Use of Models in Hydrology.  

ERIC Educational Resources Information Center

This discussion article addresses the nature of models used in hydrology. It proposes a minimalist classification of models into two categories: models built on data from observations of the processes involved, and those for which there are no observation data on any of these processes, at the scale of interest. (LZ)

de Marsily, G.

1994-01-01

28

Balancing model complexity and measurements in hydrology  

NASA Astrophysics Data System (ADS)

The Data Processing Inequality implies that hydrological modeling can only reduce, and never increase, the amount of information available in the original data used to formulate and calibrate hydrological models: I(X;Z(Y)) ? I(X;Y). Still, hydrologists around the world seem quite content building models for "their" watersheds to move our discipline forward. Hydrological models tend to have a hybrid character with respect to underlying physics. Most models make use of some well established physical principles, such as mass and energy balances. One could argue that such principles are based on many observations, and therefore add data. These physical principles, however, are applied to hydrological models that often contain concepts that have no direct counterpart in the observable physical universe, such as "buckets" or "reservoirs" that fill up and empty out over time. These not-so-physical concepts are more like the Artificial Neural Networks and Support Vector Machines of the Artificial Intelligence (AI) community. Within AI, one quickly came to the realization that by increasing model complexity, one could basically fit any dataset but that complexity should be controlled in order to be able to predict unseen events. The more data are available to train or calibrate the model, the more complex it can be. Many complexity control approaches exist in AI, with Solomonoff inductive inference being one of the first formal approaches, the Akaike Information Criterion the most popular, and Statistical Learning Theory arguably being the most comprehensive practical approach. In hydrology, complexity control has hardly been used so far. There are a number of reasons for that lack of interest, the more valid ones of which will be presented during the presentation. For starters, there are no readily available complexity measures for our models. Second, some unrealistic simplifications of the underlying complex physics tend to have a smoothing effect on possible model outcomes, thereby preventing the most obvious results of over-fitting. Thirdly, dependence within and between time series poses an additional analytical problem. Finally, there are arguments to be made that the often discussed "equifinality" in hydrological models is simply a different manifestation of the lack of complexity control. In turn, this points toward a general idea, which is actually quite popular in sciences other than hydrology, that additional data gathering is a good way to increase the information content of our descriptions of hydrological reality.

Van De Giesen, N.; Schoups, G.; Weijs, S. V.

2012-12-01

29

Treatments of Precipitation Inputs to Hydrologic Models  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydrological models are used to assess many water resources problems from agricultural use and water quality to engineering issues. The success of these models are dependent on correct parameterization; the most sensitive being the rainfall input time series. These records can come from land-based ...

30

Improving hydrology models for a changing climate  

NASA Astrophysics Data System (ADS)

Changes over time in the relationship between rainfall and catchment runoff pose a significant challenge for hydrological models, which are often calibrated under the assumption that the future relationship will be consistent with that of the past. In a recent paper, Westra et al. outlined a method for diagnosing, interpreting, and improving the capacity of models to develop predictions under such conditions.

Palus, Shannon

2014-12-01

31

Approaches to modelling hydrology and ecosystem interactions  

NASA Astrophysics Data System (ADS)

As the pressures of industry, agriculture and mining on groundwater resources increase there is a burgeoning un-met need to be able to capture these multiple, direct and indirect stresses in a formal framework that will enable better assessment of impact scenarios. While there are many catchment hydrological models and there are some models that represent ecological states and change (e.g. FLAMES, Liedloff and Cook, 2007), these have not been linked in any deterministic or substantive way. Without such coupled eco-hydrological models quantitative assessments of impacts from water use intensification on water dependent ecosystems under changing climate are difficult, if not impossible. The concept would include facility for direct and indirect water related stresses that may develop around mining and well operations, climate stresses, such as rainfall and temperature, biological stresses, such as diseases and invasive species, and competition such as encroachment from other competing land uses. Indirect water impacts could be, for example, a change in groundwater conditions has an impact on stream flow regime, and hence aquatic ecosystems. This paper reviews previous work examining models combining ecology and hydrology with a view to developing a conceptual framework linking a biophysically defensable model that combines ecosystem function with hydrology. The objective is to develop a model capable of representing the cumulative impact of multiple stresses on water resources and associated ecosystem function.

Silberstein, Richard P.

2014-05-01

32

ARMA Model Identification of Hydrologic Time Series  

NASA Astrophysics Data System (ADS)

In recent years, ARMA models have become popular for modeling geophysical time series in general and hydrologic time series in particular. The identification of the appropriate order of the model is an important stage in ARMA modeling. Such model identification is generally based on the autocorrelation and partial autocorrelation functions, although recently improvements have been obtained using the inverse autocorrelation and the inverse partial autocorrelation functions. This paper demonstrates the use of the generalized partial autocorrelation function (GPAF) and the R and S functions of Gray et al. (1978) for ARMA model identification of hydrologic time series. These functions are defined, and some recursive relations are given for ease of computation. All three functions, when presented in tabular form, have certain characteristic patterns that are useful in ARMA model identification. Several examples are included to demonstrate the usefulness of the proposed identification technique. Actual applications are made using the Saint Lawrence River and Nile River annual streamflow series.

Salas, J. D.; Obeysekera, J. T. B.

1982-08-01

33

Modeling the hydrological cycle on Mars  

NASA Astrophysics Data System (ADS)

The study provides a detailed analysis of the hydrological cycle on Mars simulated with a newly developed microphysical model, incorporated in a spectral Mars General Circulation Model. The modeled hydrological cycle is compared well with simulations of other global climate models. The simulated seasonal migration of water vapor, circulation instability, and the high degree of temporal variability of localized water vapor outbursts are shown closely consistent with recent observations. The microphysical parameterization provides a significant improvement in the modeling of ice clouds evolved over the tropics and major ancient volcanoes on Mars. The most significant difference between the simulations presented here and other GCM results is the level at which the water ice clouds are found. The model findings also support interpretation of observed thermal anomalies in the Martian tropics during northern spring and summer seasons.

Machtoub, G.

2012-03-01

34

Modeling the hydrological cycle on Mars  

NASA Astrophysics Data System (ADS)

The study provides a detailed analysis of the hydrological cycle on Mars simulated with a newly developed microphysical model, incorporated in a spectral Mars General Circulation Model. The modeled hydrological cycle is compared well with simulations of other global climate models. The simulated seasonal migration of water vapor, circulation instability, and the high degree of temporal variability of localized water vapor outbursts are shown closely consistent with recent observations. The microphysical parameterization provides a significant improvement in the modeling of ice clouds evolved over the tropics and major ancient volcanoes on Mars. The most significant difference between the simulations presented here and other GCM results is the level at which the water ice clouds are found. The model findings also support interpretation of observed thermal anomalies in the Martian tropics during northern spring and summer seasons.

Machtoub, G.

2012-01-01

35

Netherlands Hydrological Modeling Instrument - Unifying Dutch hydrological modeling expertise for national policy analysis  

Microsoft Academic Search

Dutch hydrological institutes Alterra, Deltares, Netherlands Environmental Assessment Agency and RWS Waterdienst have cooperated to build a new national hydrological model. The instrument will be used by all three ministries involved in national water policy matters, for instance drought management, manure policy and climate change issues. The basis of the modeling instrument is a state-of-the-art on-line coupling of the groundwater

J. Delsman; N. Kukuric; A. Veldhuizen; A. Tiktak; T. Kroon

2009-01-01

36

Use of KNN technique to improve the efficiency of SCE-UA optimisation method applied to the calibration of HBV Rainfall-Runoff model  

NASA Astrophysics Data System (ADS)

The Calibration of Rainfall-Runoff models can be viewed as an optimisation problem involving an objective function that measures the model performance expressed as a distance between observed and calculated discharges. Effectiveness (ability to find the optimum) and efficiency (cost expressed in number of objective function evaluations to reach the optimum) are the main criteria of choose of the optimisation method. SCE-UA is known as one of the most effective and efficient optimisation method. In this work we tried to improve the SCE-UA efficiency, in the case of the calibration of HBV model by using KNN technique to estimate the objective function. In fact after a number of iterations by SCE-UA, when objective function is evaluated by model simulation, a data base of parameter explored and respective objective function values is constituted. Within this data base it is proposed to estimate the objective function in further iterations, by an interpolation using nearest neighbours in a normalised parameter space with weighted Euclidean distance. Weights are chosen proportional to the sensitivity of parameter to objective function that gives more importance to sensitive parameter. Evaluation of model output is done through the objective function RV=R2- w |RD| where R2 is Nash Sutcliffe coefficient related to discharges, w : a weight and RD the relative bias. Applied to theoretical and practical cases in several catchments under different climatic conditions : Rottweil (Germany) and Tessa, Barbra, and Sejnane (Tunisia), the hybrid SCE-UA presents efficiency better then that of initial SCE-UA by about 20 to 30 %. By using other techniques as parameter space transformation and SCE-UA modification (2), we may obtain an algorithm two to three times faster. (1) Avi Ostfeld, Shani Salomons, "A hybrid genetic-instance learning algorithm for CE*QAL-W2 calibration", Journal of Hydrology 310 (2005) 122-125 (2) Nitin Mutil and Shie-Yui Liong, "Improved robustness and Efficiency of the SCE-UA model calibrating algorithm"

Dakhlaoui, H.; Bargaoui, Z.

2007-12-01

37

TUWmodel: an educational hydrologic model in R  

NASA Astrophysics Data System (ADS)

In order to show the advantages of using hydrologic models in R environment, particularly for educational purposes, we have implemented a conceptual rainfall-runoff model, originally written in Fortran language into R. This hydrologic model is used in many scientific studies and operational engineering applications in Austria. The model consisting of a snow, a soil moisture and a flow routing routine and run on a daily time step in a lumped or a semi-lumped way. The R environment allows to compile and use this model on different platforms and operating system, taking advantage of many additional routines already available in R (i.e. visualisation or optimisation tools). In this poster we present a set of examples that are used in a graduate level course on engineering hydrology at the Vienna University of Technology, which include: - Multi-objective calibration of the model; - Manual vs. automatic calibration; - Visualisation of model outputs and efficiencies; - Model application in ungauged catchments; - Operational runoff forecast. The flexibility of R is ideal for education, since students can easily play with the extensive list of existing functionalities and define new functions and extensions.

Parajka, J.; Rogger, M.; Kobler, U.; Salinas, J.; Nester, T.; Bloeschl, G.

2013-12-01

38

Enhancements for Hydrological Modeling in ESMF  

NASA Astrophysics Data System (ADS)

Hydrological systems connect Earth's global physical phenomena with the local environmental impacts that affect our food, health, finances, and homes. The scales and processes that hydrological modelers must span are reflected in the challenges of developing infrastructure for this community. The basic requirements - the need to assemble and couple model components, the need for efficient I/O, the need for integrated visualization, analysis, and data services - are shared with other domains, such as climate and space weather. Where hydrology goes beyond other domains is in its terrific heterogeneity. The diversity of models, data structures, grids, computing platforms, computing languages, and specialized sub-domains involved is daunting. It's not surprising that the hydrological community has spawned a variety of different integrative efforts and frameworks, with distinctly different approaches. This talk will outline how the Earth System Modeling Framework (ESMF), which began in realm of high performance computing for the climate and weather domain, has begun to address the needs of hydrological modelers. We will describe ESMF's new mesh and observational data stream data structures, which join its structured grids and lower-level, index-space constructs as options for data representation, and the flexible, parallel regridding services that can interpolate data between them. The ESMF team is exploring a service oriented architecture approach to computing language and platform diversity, and to interfacing with other standard frameworks. We have also implemented C interfaces for optimized coupling between C and Fortran codes on traditional high performance computing platforms. To address the variety of components available, distributed communities, and integration with data and other services, ESMF has been exhancing its ability to store and write standard component and field metadata, and to link that metadata with full-service science portals. This enables components to be browsed and linked to the data they ingest and produce. The hope is that these enhancements will facilitate integration with other efforts in the hydrology community, and coupling interfaces to the domains such as weather prediction where ESMF is becoming part of the standard infrastructure.

Deluca, C.; Oehmke, R.; Neckels, D.; Theurich, G.; O'Kuinghttons, R.; de Fainchtein, R.; Murphy, S.; Dunlap, R.

2008-12-01

39

Hydrology  

ERIC Educational Resources Information Center

The past year saw a re-emphasis on the practical aspects of hydrology due to regional drought patterns, urban flooding, and agricultural and energy demands on water resources. Highlights of hydrologic symposia, publications, and events are included. (MA)

Sharp, John M., Jr.

1978-01-01

40

Basic Hydrology in Earth System Models  

NASA Astrophysics Data System (ADS)

As Earth System Models continue to advance and include complex biogeochemical and human interactions, some of the basic hydrologic principles are still inadequately represented. Examples are two-way groundwater-surface water exchange (with rivers, floodplains, wetlands, and root-zone soil) and lateral groundwater convergence (from hillslope to continent scales). We discuss how incorporating these processes fundamentally changes the simulated seasonal dynamics of river flow, flooding, wetlands, soil moisture, and ET, and how the resulting hydrologic gradients shape vegetation and carbon cycling, based on observational synthesis and model simulations. We also briefly highlight the key challenges ahead including the need to establish a global dataset of Earth's crustal properties for simulating fluid flow below the land surface.

Fan, Y.; Miguez-Macho, G.; Li, H.; Schaller, M. F.; Weaver, C. P.

2012-12-01

41

Spatial resolution considerations for urban hydrological modelling  

NASA Astrophysics Data System (ADS)

Hydrological model simulations can be applied to evaluate the performance of low impact development (LID) tools in urban areas. However, the assessment for large-scale urban areas remains a challenge due to the required high spatial resolution and limited availability of field measurements for model calibration. This study proposes a methodology to parameterize a hydrological model (SWMM) with sufficiently high spatial resolution and direct accessibility of model parameters for LID performance simulation applicable to a large-scale ungauged urban area. Based on calibrated high-resolution models for three small-scale study catchments (6-12 ha), we evaluated how constraints implied by large-scale urban modelling, such as data limitations, affect the model results. The high-resolution surface representation, resulting in subcatchments of uniform surface types, reduced the number of calibration parameters. Calibration conducted independently for all catchments yielded similar parameter values for same surface types in each study catchment. These results suggest the applicability of the parameter values calibrated for high resolution models to be regionalized to larger, ungauged urban areas. The accessibility of surface specific model parameters for LID simulation is then also retained. Conducted perturbations in spatial resolution through sewer network truncation showed that while the runoff volume was mostly unaffected by resolution perturbations, lower resolutions resulted in over-simulation of peak flows due to excessively rapid catchment response to storm events. Our results suggest that a hydrological model where parameter values are adopted from high-resolution models and that is developed based on a minimum conduit diameter of 300 mm provides good simulation performance and is applicable to large-scale urban areas with reasonable effort.

Krebs, G.; Kokkonen, T.; Valtanen, M.; Setälä, H.; Koivusalo, H.

2014-05-01

42

Evaluation of statistical models for forecast errors from the HBV model  

NASA Astrophysics Data System (ADS)

SummaryThree statistical models for the forecast errors for inflow into the Langvatn reservoir in Northern Norway have been constructed and tested according to the agreement between (i) the forecast distribution and the observations and (ii) median values of the forecast distribution and the observations. For the first model observed and forecasted inflows were transformed by the Box-Cox transformation before a first order auto-regressive model was constructed for the forecast errors. The parameters were conditioned on weather classes. In the second model the Normal Quantile Transformation (NQT) was applied on observed and forecasted inflows before a similar first order auto-regressive model was constructed for the forecast errors. For the third model positive and negative errors were modeled separately. The errors were first NQT-transformed before conditioning the mean error values on climate, forecasted inflow and yesterday's error. To test the three models we applied three criterions: we wanted (a) the forecast distribution to be reliable; (b) the forecast intervals to be narrow; (c) the median values of the forecast distribution to be close to the observed values. Models 1 and 2 gave almost identical results. The median values improved the forecast with Nash-Sutcliffe R eff increasing from 0.77 for the original forecast to 0.87 for the corrected forecasts. Models 1 and 2 over-estimated the forecast intervals but gave the narrowest intervals. Their main drawback was that the distributions are less reliable than Model 3. For Model 3 the median values did not fit well since the auto-correlation was not accounted for. Since Model 3 did not benefit from the potential variance reduction that lies in bias estimation and removal it gave on average wider forecasts intervals than the two other models. At the same time Model 3 on average slightly under-estimated the forecast intervals, probably explained by the use of average measures to evaluate the fit.

Engeland, Kolbjørn; Renard, Benjamin; Steinsland, Ingelin; Kolberg, Sjur

2010-04-01

43

Evaluation Of Statistical Models For Forecast Errors From The HBV-Model  

NASA Astrophysics Data System (ADS)

Three statistical models for the forecast errors for inflow to the Langvatn reservoir in Northern Norway have been constructed and tested according to how well the distribution and median values of the forecasts errors fit to the observations. For the first model observed and forecasted inflows were transformed by the Box-Cox transformation before a first order autoregressive model was constructed for the forecast errors. The parameters were conditioned on climatic conditions. In the second model the Normal Quantile Transformation (NQT) was applied on observed and forecasted inflows before a similar first order autoregressive model was constructed for the forecast errors. For the last model positive and negative errors were modeled separately. The errors were first NQT-transformed before a model where the mean values were conditioned on climate, forecasted inflow and yesterday's error. To test the three models we applied three criterions: We wanted a) the median values to be close to the observed values; b) the forecast intervals to be narrow; c) the distribution to be correct. The results showed that it is difficult to obtain a correct model for the forecast errors, and that the main challenge is to account for the auto-correlation in the errors. Model 1 and 2 gave similar results, and the main drawback is that the distributions are not correct. The 95% forecast intervals were well identified, but smaller forecast intervals were over-estimated, and larger intervals were under-estimated. Model 3 gave a distribution that fits better, but the median values do not fit well since the auto-correlation is not properly accounted for. If the 95% forecast interval is of interest, Model 2 is recommended. If the whole distribution is of interest, Model 3 is recommended.

Engeland, K.; Kolberg, S.; Renard, B.; Stensland, I.

2009-04-01

44

Use of different sampling schemes in machine learning-based prediction of hydrological models' uncertainty  

NASA Astrophysics Data System (ADS)

In recent years, a lot of attention in the hydrologic literature is given to model parameter uncertainty analysis. The robustness estimation of uncertainty depends on the efficiency of sampling method used to generate the best fit responses (outputs) and on ease of use. This paper aims to investigate: (1) how sampling strategies effect the uncertainty estimations of hydrological models, (2) how to use this information in machine learning predictors of models uncertainty. Sampling of parameters may employ various algorithms. We compared seven different algorithms namely, Monte Carlo (MC) simulation, generalized likelihood uncertainty estimation (GLUE), Markov chain Monte Carlo (MCMC), shuffled complex evolution metropolis algorithm (SCEMUA), differential evolution adaptive metropolis (DREAM), partical swarm optimization (PSO) and adaptive cluster covering (ACCO) [1]. These methods were applied to estimate uncertainty of streamflow simulation using conceptual model HBV and Semi-distributed hydrological model SWAT. Nzoia catchment in West Kenya is considered as the case study. The results are compared and analysed based on the shape of the posterior distribution of parameters, uncertainty results on model outputs. The MLUE method [2] uses results of Monte Carlo sampling (or any other sampling shceme) to build a machine learning (regression) model U able to predict uncertainty (quantiles of pdf) of a hydrological model H outputs. Inputs to these models are specially identified representative variables (past events precipitation and flows). The trained machine learning models are then employed to predict the model output uncertainty which is specific for the new input data. The problem here is that different sampling algorithms result in different data sets used to train such a model U, which leads to several models (and there is no clear evidence which model is the best since there is no basis for comparison). A solution could be to form a committee of all models U and to sue a dynamic averaging scheme to generate the final output. [1] N. Kayastha, D. L. Shrestha and D. P. Solomatine. Experiments with several methods of parameter uncertainty estimation in hydrological modeling. Proc. 9th Intern. Conf. on Hydroinformatics, Tianjin, China, September 2010. [2] D. L. Shrestha, N. Kayastha, and D. P. Solomatine. A novel approach to parameter uncertainty analysis of hydrological models using neural networks. Hydrol. Earth Syst. Sci., 13, 1235-1248, 2009.

Kayastha, Nagendra; Solomatine, Dimitri; Lal Shrestha, Durga; van Griensven, Ann

2013-04-01

45

Distributed Hydrologic Models for Flow Forecasts - Part 1  

NSDL National Science Digital Library

Distributed Hydrologic Models for Flow Forecasts – Part 1 provides a basic description of distributed hydrologic models and how they work. This module is the first in a two-part series focused on the science of distributed models and their applicability in different situations. Presented by Dr. Dennis Johnson, the module begins with a review of hydrologic models, and then examines the differences between lumped and distributed models. It explains how lumped models may be distributed by subdividing the basin and suggests when distributed hydrologic models are most appropriate. Other topics covered include the advantages of physically-based versus conceptual approaches and some strengths and challenges associated with distributed modeling.

2014-09-14

46

Multivariate Probabilistic Analysis of an Hydrological Model  

NASA Astrophysics Data System (ADS)

Model predictions derived based on rainfall measurements and hydrological model results are often limited by the systematic error of measuring instruments, by the intrinsic variability of the natural processes and by the uncertainty of the mathematical representation. We propose a means to identify such sources of uncertainty and to quantify their effects based on point-estimate approaches, as a valid alternative to cumbersome Montecarlo methods. We present uncertainty analyses on the hydrologic response to selected meteorological events, in the mountain streamflow-generating portion of the Brenta basin at Bassano del Grappa, Italy. The Brenta river catchment has a relatively uniform morphology and quite a heterogeneous rainfall-pattern. In the present work, we evaluate two sources of uncertainty: data uncertainty (the uncertainty due to data handling and analysis) and model uncertainty (the uncertainty related to the formulation of the model). We thus evaluate the effects of the measurement error of tipping-bucket rain gauges, the uncertainty in estimating spatially-distributed rainfall through block kriging, and the uncertainty associated with estimated model parameters. To this end, we coupled a deterministic model based on the geomorphological theory of the hydrologic response to probabilistic methods. In particular we compare the results of Monte Carlo Simulations (MCS) to the results obtained, in the same conditions, using Li's Point Estimate Method (LiM). The LiM is a probabilistic technique that approximates the continuous probability distribution function of the considered stochastic variables by means of discrete points and associated weights. This allows to satisfactorily reproduce results with only few evaluations of the model function. The comparison between the LiM and MCS results highlights the pros and cons of using an approximating method. LiM is less computationally demanding than MCS, but has limited applicability especially when the model response is highly nonlinear. Higher-order approximations can provide more accurate estimations, but reduce the numerical advantage of the LiM. The results of the uncertainty analysis identify the main sources of uncertainty in the computation of river discharge. In this particular case the spatial variability of rainfall and the model parameters uncertainty are shown to have the greatest impact on discharge evaluation. This, in turn, highlights the need to support any estimated hydrological response with probability information and risk analysis results in order to provide a robust, systematic framework for decision making.

Franceschini, Samuela; Marani, Marco

2010-05-01

47

Modeling hydrologic and ecologic responses using a new eco-hydrological model for identification of droughts  

NASA Astrophysics Data System (ADS)

severely damages water and agricultural resources, and both hydrological and ecological responses are important for its understanding. First, precipitation deficit induces soil moisture deficiency and high plant water stress causing agricultural droughts. Second, hydrological drought characterized by deficit of river discharge and groundwater follows agricultural drought. However, contributions of vegetation dynamics to these processes at basin scale have not been quantified. To address this issue, we develop an eco-hydrological model that can calculate river discharge, groundwater, energy flux, and vegetation dynamics as diagnostic variables at basin scale within a distributed hydrological modeling framework. The model is applied to drought analysis in the Medjerda River basin. From model inputs and outputs, we calculate drought indices for different drought types. The model shows reliable accuracy in reproducing observed river discharge in long-term (19 year) simulation. Moreover, the drought index calculated from the model-estimated annual peak of leaf area index correlates well (correlation coefficient r = 0.89) with the drought index from nationwide annual crop production, which demonstrates that the modeled leaf area index is capable of representing agricultural droughts related to historical food shortages. We show that vegetation dynamics have a more rapid response to meteorological droughts than river discharge and groundwater dynamics in the Medjerda basin because vegetation dynamics are sensitive to soil moisture in surface layers, whereas soil moisture in deeper layers strongly contributes to streamflow and groundwater level. Our modeling framework can contribute to analyze drought progress, although analyses for other climate conditions are needed.

Sawada, Yohei; Koike, Toshio; Jaranilla-Sanchez, Patricia Ann

2014-07-01

48

An operational GLS model for hydrologic regression  

USGS Publications Warehouse

Recent Monte Carlo studies have documented the value of generalized least squares (GLS) procedures to estimate empirical relationships between streamflow statistics and physiographic basin characteristics. This paper presents a number of extensions of the GLS method that deal with realities and complexities of regional hydrologic data sets that were not addressed in the simulation studies. These extensions include: (1) a more realistic model of the underlying model errors; (2) smoothed estimates of cross correlation of flows; (3) procedures for including historical flow data; (4) diagnostic statistics describing leverage and influence for GLS regression; and (5) the formulation of a mathematical program for evaluating future gaging activities. ?? 1989.

Tasker, Gary D.; Stedinger, J.R.

1989-01-01

49

Modeling of aggregated hydrologic time series  

NASA Astrophysics Data System (ADS)

The concept of aggregation of the most commonly used models of seasonal hydrologic time series is the main subject discussed herein. The PAR(1) and PARMA(1, 1) models are assumed for representing the seasonal series and their equivalent stationarity and invertibility conditions are given. Likewise explicit expressions are given for determining the periodic covariance structure of such models and the concept of aggregation is illustrated by deriving the model of the corresponding annual series. Since the models of the seasonal series dictate the type of model of the annual series, then a unique structural linkage in the usual linear disaggregation model may be obtained in closed form. Seasonal and annual flows of the Niger River are used to illustrate some of the estimation procedures based on the foregoing aggregation approach.

Obeysekera, J. T. B.; Salas, J. D.

1986-10-01

50

Evaluating spatial patterns in hydrological modeling  

NASA Astrophysics Data System (ADS)

Recent advances in hydrological modeling towards fully distributed grid based model codes, increased availability of spatially distributed data (remote sensing and intensive field studies) and more computational power allow a shift towards a spatial model evaluation away from the traditional aggregated evaluation. The consideration of spatially aggregated observations, in form of river discharge, in the evaluation process does not ensure a correct simulation of catchment-inherent distributed variables. The integration of spatial data and hydrological models is limited due to a lack of suitable metrics to evaluate similarity of spatial patterns. This study is engaged with the development of a novel set of performance metrics that capture spatial patterns and go beyond global statistics. The metrics are required to be easy, flexible and especially targeted to compare observed and simulated spatial patterns of hydrological variables. Four quantitative methodologies for comparing spatial patterns are brought forward: (1) A fuzzy set approach that incorporates both fuzziness of location and fuzziness of category. (2) Kappa statistic that expresses the similarity between two maps based on a contingency table (error matrix). (3) An extended version of (2) by considering both fuzziness in location and fuzziness in category. (4) Increasing the information content of a single cell by aggregating neighborhood cells at different window sizes; then computing mean and standard deviation. The identified metrics are tested on observed and simulated land surface temperature maps in a groundwater dominated catchment in western Denmark. The observed data originates from the MODIS satellite and MIKE SHE, a coupled and fully distributed hydrological model, serves as the modelling tool. Synthetic land surface temperature maps are generated to further address strengths and weaknesses of the metrics. The metrics are tested in different parameter optimizing frameworks, where they are defined as objective functions individually and collectively. Additionally discharge data, representing a different observational dataset, is included in the optimization process which enables a multi constrained evaluation of the model. This allows testing different optimization frameworks under consideration of observable spatial patterns and discharge data which represents a spatially aggregated catchment observation.

Koch, Julian; Stisen, Simon; Høgh Jensen, Karsten

2014-05-01

51

Attributing spatial patterns of hydrological model performance  

NASA Astrophysics Data System (ADS)

Global hydrological models and land surface models are used to understand and simulate the global terrestrial water cycle. They are, in particular, applied to assess the current state of global water resources, to identify anthropogenic pressures on the global water system, and to assess impacts of global and climate change on water resources. Especially in data-scarce regions, the growing availability of remote sensing products, e.g. GRACE estimates of changes in terrestrial water storage, evaporation or soil moisture estimates, has added valuable information to force and constrain these models as they facilitate the calibration and validation of simulated states and fluxes other than stream flow at large spatial scales. Nevertheless, observed discharge records provide important evidence to evaluate the quality of water availability estimates and to quantify the uncertainty associated with these estimates. Most large scale modelling approaches are constrained by simplified physical process representations and they implicitly rely on the assumption that the same model structure is valid and can be applied globally. It is therefore important to understand why large scale hydrological models perform good or poor in reproducing observed runoff and discharge fields in certain regions, and to explore and explain spatial patterns of model performance. We present an extensive evaluation of the global water model WaterGAP (Water - Global Assessment and Prognosis) to simulate 20th century discharges. The WaterGAP modeling framework comprises a hydrology model and several water use models and operates in its current version, WaterGAP3, on a 5 arc minute global grid and . Runoff generated on the individual grid cells is routed along a global drainage direction map taking into account retention in natural surface water bodies, i.e. lakes and wetlands, as well as anthropogenic impacts, i.e. flow regulation and water abstraction for agriculture, industry and domestic purposes as calculated by the water use models. Simulated discharges for the period 1958-2001 are evaluated against more than 1500 observed discharge records provided by the Global Runoff Data Centre (GRDC). Globally, the selected gauging stations differ substantially in terms of upstream area (3000 -- 3.6 mill sqkm) and their available time series (between 5 and > 100 yrs). We assess the model performance by applying complementary metrics such as Nash-Sutcliffe-Efficiency or water balance related coefficients. Moreover, based on these metrics, we investigate if and how physiographic catchment characteristics and climate conditions impact model efficiency and identify possible underlying determinants of spatial patterns of model performance.

Eisner, S.; Malsy, M.; Flörke, M.

2013-12-01

52

Improving Hydrology in Land Ice Models  

NASA Astrophysics Data System (ADS)

Community Earth System Model Land Ice Working Group Meeting; Boulder, Colorado, 13 January 2011 ; Recent observations indicate that mass loss from glaciers and ice sheets (“land ice”) is increasing. The drivers of these changes are not well understood, and modeling the land ice response to them remains challenging. As a result, the Intergovernmental Panel on Climate Change explicitly avoided speculating on 21st-century sea level rise from ice dynamical processes in its fourth assessment report. The mismatch between observations of land ice change and model skill at mimicking those changes is behind recent efforts to develop next-generation land ice models. Necessary improvements to existing models include improved dynamics, coupling to climate models, and better representations of important boundary conditions and physical processes. Basal sliding, the primary control on the rate of land ice delivery to the oceans, is one such boundary condition that is largely controlled by land ice hydrology.

Price, Stephen; Flowers, Gwenn; Schoof, Christian

2011-05-01

53

Calibration of hydrological models in glacierized catchments  

NASA Astrophysics Data System (ADS)

Glacierized catchments are important source regions for water, and detailed knowledge of water availability is a prerequisite for good resource management strategies. Reliable and physically consistent runoff simulations become even more important if climate change impacts on alpine water resources are to be assessed. However, hydrological modeling of glacierized catchments is challenging ice melt which represents an additional source of water. Thus, adequate calibration strategies are needed especially in data scarce regions. An important question is how powerful a limited amount of data might be for model calibration. Accordingly, we analyzed the calibration power of limited discharge measurements, mass balance observations and the combination of by means of both Monte Carlo analyzes and multi-criteria model performance evaluation. Ensembles of 100 parameter sets were selected by evaluating the simulations based on a limited and discrete number of discharge measurements, glacier mass balance, and the combination of discharge and mass balance observations. Using these ensembles then the runoff was simulated and evaluated for the entire runoff series. The results for the Vernagtferner catchment and the Venter Ache catchment in Austria indicated that a single annual glacier mass balance observation contained useful information to constrain hydrological models. Combining mass balance observations with a few discharge data improved the internal consistency and significantly reduced the uncertainties compared to parameter set selections based on discharge measurements alone. Information on discharge was required for at least 3 days during the melting season to obtain good ensemble predictions.

Konz, Markus; Seibert, Jan; Braun, Ludwig; Burlando, Paolo

2010-05-01

54

Coupled land surface/hydrologic/atmospheric models  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

55

Hydrologic Process Modules of the Regional Simulation Model: An Overview  

Microsoft Academic Search

The Regional Simulation Model is a regional finite-volume, aquifer-stream-surface hydrology model under development by the South Florida Water Management District. The Hydrologic Process Modules (HPM) are designed to solve the local surface water hydrology for RSM, where an HPM is assigned to each cell in the irregular mesh. The HPMs are solved explicitly at the beginning of each model time

Eric Flaig; Randy VanZee; Wasantha Lal

56

Dalton Lecture: How far can we go in distributed hydrological modelling?Hydrology and Earth System Sciences, 5(1), 1-12 (2001) EGS How far can we go in distributed hydrological modelling?  

E-print Network

1 Dalton Lecture: How far can we go in distributed hydrological modelling?Hydrology and Earth System Sciences, 5(1), 1-12 (2001) © EGS How far can we go in distributed hydrological modelling? Keith hydrological models in hydrology as an expression of a pragmatic realism. Some of the problems of distributed

Paris-Sud XI, Université de

57

The skill of seasonal ensemble low-flow forecasts in the Moselle River for three different hydrological models  

NASA Astrophysics Data System (ADS)

This paper investigates the skill of 90-day low-flow forecasts using two conceptual hydrological models and one data-driven model based on Artificial Neural Networks (ANNs) for the Moselle River. The three models, i.e. HBV, GR4J and ANN-Ensemble (ANN-E), all use forecasted meteorological inputs (precipitation P and potential evapotranspiration PET), whereby we employ ensemble seasonal meteorological forecasts. We compared low-flow forecasts for five different cases of seasonal meteorological forcing: (1) ensemble P and PET forecasts; (2) ensemble P forecasts and observed climate mean PET; (3) observed climate mean P and ensemble PET forecasts; (4) observed climate mean P and PET and (5) zero P and ensemble PET forecasts as input for the models. The ensemble P and PET forecasts, each consisting of 40 members, reveal the forecast ranges due to the model inputs. The five cases are compared for a lead time of 90 days based on model output ranges, whereas the models are compared based on their skill of low-flow forecasts for varying lead times up to 90 days. Before forecasting, the hydrological models are calibrated and validated for a period of 30 and 20 years respectively. The smallest difference between calibration and validation performance is found for HBV, whereas the largest difference is found for ANN-E. From the results, it appears that all models are prone to over-predict runoff during low-flow periods using ensemble seasonal meteorological forcing. The largest range for 90-day low-flow forecasts is found for the GR4J model when using ensemble seasonal meteorological forecasts as input. GR4J, HBV and ANN-E under-predicted 90-day-ahead low flows in the very dry year 2003 without precipitation data. The results of the comparison of forecast skills with varying lead times show that GR4J is less skilful than ANN-E and HBV. Overall, the uncertainty from ensemble P forecasts has a larger effect on seasonal low-flow forecasts than the uncertainty from ensemble PET forecasts and initial model conditions.

Demirel, M. C.; Booij, M. J.; Hoekstra, A. Y.

2015-01-01

58

Hydrology  

ERIC Educational Resources Information Center

Lists many recent research projects in hydrology, including flow in fractured media, improvements in remote-sensing techniques, effects of urbanization on water resources, and developments in drainage basins. (MLH)

Sharp, John M.

1977-01-01

59

Modeling hydrologic processes at the residential scale  

NASA Astrophysics Data System (ADS)

In California, urbanization has led to polluted runoff, flooding during winter, and water shortages during summer. There is growing interest in application of microscale hydrologic solutions that eliminate storm runoff and conserve water at the source. In this study, a physically-based numerical model was developed to better understand hydrologic processes at the residential scale and the interaction of these processes among different Best Management Practices (BMPs). This model calculates all in-flow and out-flow using an hourly interval over a full year or for specific storm events. Water enters the system via precipitation and irrigation and leaves the system via evapotranspiration, surface and subsurface runoff, and from percolation to groundwater. The model was applied to two single-family residential parcels in Los Angeles. Two years of data collected from the control and treatment sites were used to calibrate and validate the model. More than 97% of storm runoff to the street was eliminated with installation of low-cost BMPs (i.e., rain gutters that direct roof runoff to a lawn retention basin and a driveway interceptor that directs runoff to a drywell in the lawn retention basin). Evaluated individually, the driveway interceptor was the most effective BMP for storm runoff reduction (65%), followed by the rain gutter installation (28%), and lawn converted to retention basin (12%). Installation of an 11 m3 cistern did not substantially reduce runoff, but did provide storage for 9% of annual irrigation demand. Simulated landscape irrigation demand was reduced 53% by increasing efficiency through use of a drip irrigation system for shrubs, and adjusting monthly application rates based on evapotranspirational water demand. The model showed that infiltration and surface runoff processes were particularly sensitive to the soil's physical properties and its effective depth. If the existing loam soil were replaced by clay soil annual runoff discharge to the street would be increased by 63% when climate and landscape features remained unchanged.

Xiao, Q.; McPherson, G.; Simpson, J.; Ustin, S.

2003-12-01

60

Hydrologic modeling with uncertain input parameters  

NASA Astrophysics Data System (ADS)

Erosion risk is recognized as a major threat whose consequences affect urbanized and agricultural areas. Recent assessments of the predictive abilities of erosion models show the difficulty to correctly predict the spatial patterns of erosion and deposition. This is due to the high sensibility of the model to input parameters that contain large spatial and temporal variability. Many studies concluded that model outputs are very sensitive to input hydrological parameters, especially to the saturated hydraulic conductivity. Here, we use an erosion model coupling the Shallow Water equations with the Hairsine-Rose soil erosion which can integrate different sediment size classes. As the scale of modeling is different from the scale of observed or measured data, we use a stochastic distribution of relevant input parameters to represent the micro-scale. A first part of the study concerns the rainfall/runoff model in which the saturated hydraulic conductivity is considered as an uncertain input parameter. A second part is dedicated to the influence of soil parameters in the erosion model. For each part, we evaluate how uncertainties on the inputs impact the surface runoff or the erosion model outputs during various types of rainfall events. We test different stochastic tools to quantify the propagation of uncertainties (Monte Carlo method, Karhunen-Loève expansion…) and we use numerical test cases representing fields or hillslope to assess the methodology in the context of runoff and soil erosion modeling. Simulation results allow us to know where effort should be concentrated when collecting input parameters and limit output error.

Rousseau, M.; Cerdan, O.; Ern, A.; Le Maître, O.; Sochala, P.

2012-04-01

61

Operational use of distributed hydrological models. Experiences and challenges at a Norwegian hydropower company (Agder Energi).  

NASA Astrophysics Data System (ADS)

The Scandinavian hydropower industry has traditionally adopted the lumped conceptual hydrological model - HBV, as the tool for producing forecasts of inflows and mountain snow packs. Such forecasting systems - based on lumped conceptual models - have several drawbacks. Firstly, a lumped model does not produce spatial data, and comparisons with remote sensed snow cover data (which are now available) are complicated. Secondly, several climate parameters such as wind speed are now becoming more available and can potentially improve forecasts due to improved estimates of precipitation gauge efficiency, and more physically correct calculation of turbulent heat fluxes. At last, when the number of catchments increases, it is cumbersome and slow to run multiple hydrology models compared to running one model for all catchments. With the drawbacks of the lumped hydrology models in mind, and with inspiration from other forecasting systems using distributed models, Agder Energy decided to develop a forecasting system applying a physically based distributed model. In this paper we describe an operational inflow and snowpack forecast system developed for the Scandinavian mountain range. The system applies a modern macroscale land surface hydrology model (VIC) which in combination with historical climate data and weather predictions can be used to produce both short-term, and seasonal forecasts of inflow and mountain snowpack. Experiences with the forecast system are illustrated using results from individual subcatchments as well as aggregated regional forecasts of inflow and snowpack. Conversion of water volumes into effective energy inflow are also presented and compared to data from the Nordic hydropower system. Further on, we document several important "lessons-learned" that may be of interest to the hydrological research community. Specifically a semi-automatic data cleansing system combining spatial and temporal visualization techniques with statistical procedures are combined into a robust and fast data cleansing and interpolation system. One experience from this work is that advanced interpolation techniques (kriging), do not outperform calibrated inverse distance methods when also computational speed is used as a criteria for model selection. The paper also discusses several challenges related to uncertainty in simulated snow reservoir, regionalization of parameters, choice of spatial resolution, techniques for reducing computational needs without compromising information needs, amongst others.

Viggo Matheussen, Bernt; Andresen, Arne; Weisser, Claudia

2014-05-01

62

A RETROSPECTIVE ANALYSIS OF MODEL UNCERTAINTY FOR FORECASTING HYDROLOGIC CHANGE  

EPA Science Inventory

GIS-based hydrologic modeling offers a convenient means of assessing the impacts associated with land-cover/use change for environmental planning efforts. Alternative future scenarios can be used as input to hydrologic models and compared with existing conditions to evaluate pot...

63

Use of Hydrologic and Hydrodynamic Modeling for Ecosystem Restoration  

Microsoft Academic Search

Planning and implementation of unprecedented projects for restoring the greater Everglades ecosystem are underway and the hydrologic and hydrodynamic modeling of restoration alternatives has become essential for success of restoration efforts. In view of the complex nature of the South Florida water resources system, regional-scale (system-wide) hydrologic models have been developed and used extensively for the development of the Comprehensive

Jayantha Obeysekera; Laura Kuebler; Shabbir Ahmed; Miao-LI Chang; Vic Engel; Christian Langevin; Eric Swain; Yongshan Wan

2011-01-01

64

Selection of hydrologic modeling approaches for climate change assessment: A comparison of model scale and structures  

E-print Network

, Editor-in-Chief Keywords: Hydrologic model Hydrologic model parameterization VIC PRMS GSFLOW Uncertainty-scale approach (using the PRMS model; 29,700 km2 area), and a site-specific approach (the GSFLOW model; 4700 km2

Tullos, Desiree

65

Ensemble evaluation of hydrological model hypotheses  

NASA Astrophysics Data System (ADS)

It is demonstrated for the first time how model parameter, structural and data uncertainties can be accounted for explicitly and simultaneously within the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. As an example application, 72 variants of a single soil moisture accounting store are tested as simplified hypotheses of runoff generation at six experimental grassland field-scale lysimeters through model rejection and a novel diagnostic scheme. The fields, designed as replicates, exhibit different hydrological behaviors which yield different model performances. For fields with low initial discharge levels at the beginning of events, the conceptual stores considered reach their limit of applicability. Conversely, one of the fields yielding more discharge than the others, but having larger data gaps, allows for greater flexibility in the choice of model structures. As a model learning exercise, the study points to a "leaking" of the fields not evident from previous field experiments. It is discussed how understanding observational uncertainties and incorporating these into model diagnostics can help appreciate the scale of model structural error.

Krueger, Tobias; Freer, Jim; Quinton, John N.; MacLeod, Christopher J. A.; Bilotta, Gary S.; Brazier, Richard E.; Butler, Patricia; Haygarth, Philip M.

2010-07-01

66

Hydrology  

NASA Astrophysics Data System (ADS)

Water in its different forms has always been a source of wonder, curiosity and practical concern for humans everywhere. Hydrology - An Introduction presents a coherent introduction to the fundamental principles of hydrology, based on the course that Wilfried Brutsaert has taught at Cornell University for the last thirty years. Hydrologic phenomena are dealt with at spatial and temporal scales at which they occur in nature. The physics and mathematics necessary to describe these phenomena are introduced and developed, and readers will require a working knowledge of calculus and basic fluid mechanics. The book will be invaluable as a textbook for entry-level courses in hydrology directed at advanced seniors and graduate students in physical science and engineering. In addition, the book will be more broadly of interest to professional scientists and engineers in hydrology, environmental science, meteorology, agronomy, geology, climatology, oceanology, glaciology and other earth sciences. Emphasis on fundamentals Clarification of the underlying physical processes Applications of fluid mechanics in the natural environment

Brutsaert, Wilfried

2005-08-01

67

Coupling meteorological and hydrological models for flood forecasting Hydrology and Earth System Sciences, 9(4), 333346 (2005) EGU  

E-print Network

Coupling meteorological and hydrological models for flood forecasting 333 Hydrology and Earth System Sciences, 9(4), 333346 (2005) © EGU Coupling meteorological and hydrological models for flood.bartholmes@jrc.it Abstract This paper deals with the problem of analysing the coupling of meteorological meso

Paris-Sud XI, Université de

68

Distributed hydrological modeling study with the dynamic water yielding mechanism and RS\\/GIS techniques  

Microsoft Academic Search

Water yielding in the hydrologic cycle is a temporally and spatially varied process. However, water yielding mechanics expressed in hydrological simulations seldom accurately characterize such dynamic processes thus weakens the simulation capabilities of present hydrological modeling systems. In this study a conceptual distributed hydrological model entitled ESSI (infiltration Excess and Saturation excess Soil-water Integration model for hydrology) was developed for

Dong Zhang; Wanchang Zhang

2006-01-01

69

Updating of states in operational hydrological models  

NASA Astrophysics Data System (ADS)

Operationally the main purpose of hydrological models is to provide runoff forecasts. The quality of the model state and the accuracy of the weather forecast together with the model quality define the runoff forecast quality. Input and model errors accumulate over time and may leave the model in a poor state. Usually model states can be related to observable conditions in the catchment. Updating of these states, knowing their relation to observable catchment conditions, influence directly the forecast quality. Norway is internationally in the forefront in hydropower scheduling both on short and long terms. The inflow forecasts are fundamental to this scheduling. Their quality directly influence the producers profit as they optimize hydropower production to market demand and at the same time minimize spill of water and maximize available hydraulic head. The quality of the inflow forecasts strongly depends on the quality of the models applied and the quality of the information they use. In this project the focus has been to improve the quality of the model states which the forecast is based upon. Runoff and snow storage are two observable quantities that reflect the model state and are used in this project for updating. Generally the methods used can be divided in three groups: The first re-estimates the forcing data in the updating period; the second alters the weights in the forecast ensemble; and the third directly changes the model states. The uncertainty related to the forcing data through the updating period is due to both uncertainty in the actual observation and to how well the gauging stations represent the catchment both in respect to temperatures and precipitation. The project looks at methodologies that automatically re-estimates the forcing data and tests the result against observed response. Model uncertainty is reflected in a joint distribution of model parameters estimated using the Dream algorithm.

Bruland, O.; Kolberg, S.; Engeland, K.; Gragne, A. S.; Liston, G.; Sand, K.; Tøfte, L.; Alfredsen, K.

2012-04-01

70

Hydrology  

USGS Publications Warehouse

Hydrologic process are the main determinants of the type of wetland located on a site. Precipitation, groundwater, or flooding interact with soil properties and geomorphic setting to yield a complex matrix of conditions that control groundwater flux, water storage and discharge, water chemistry, biotic productivity, biodiversity, and biogeochemical cycling. Hydroperiod affects many abiotic factors that in turn determine plant and animal species composition, biodiversity, primary and secondary productivity, accumulation, of organic matter, and nutrient cycling. Because the hydrologic regime has a major influence on wetland functioning, understanding how hydrologic changes influence ecosystem processes is essential, especially in light of the pressures placed on remaining wetlands by society's demands for water resources and by potential global changes in climate.

Eisenbies, Mark H.; Hughes, W. Brian

2000-01-01

71

Global scale hydrology - Advances in land surface modeling  

SciTech Connect

Research into global scale hydrology is an expanding area that includes researchers from the meteorology, climatology, ecology and hydrology communities. This paper reviews research in this area carried out in the United States during the last IUGG quadrennial period of 1987-1990. The review covers the representation of land-surface hydrologic processes for general circulation models (GCMs), sensitivity analysis of these representations on global hydrologic fields like precipitation, regional studies of climate that have global hydrologic implications, recent field studies and experiments whose aims are the improved understanding of land surface-atmospheric interactions, and the use of remotely sensed data for the further understanding of the spatial variability of surface hydrologic processes that are important at regional and global climate scales. 76 refs.

Wood, E.F. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

72

Hydrological Modelling of Small Catchments Using Swat  

NASA Astrophysics Data System (ADS)

The data from a 142ha catchment in Eastern England(Colworth, Bedfordshire)are be- ing used to investigate the performance of the USDA SWAT software for modelling hydrology of small catchments. Stream flow at the catchment outlet has been mon- itored since October 1999. About 50% of the total catchment is directly controlled within one farm and a rotation of wheat, oil seed rape, grass, linseed, beans and peas is grown. Three years of stream flow and climate data are available. Calibration and validation of stream flow was carried out with both runoff modelling options in the SWAT model (USDA curve number method and the Green and Ampt method). The Nash and Sutcliffe efficiencies for the calibration period were 66% and 63% respec- tively. The performance of SWAT was better in the validation period as a whole, with regard to timing of peaks, baseflow values and Nash and Sutcliffe efficiency. An ef- ficiency of 70% was obtained using the curve number method, which is comparable with the efficiencies obtainable with more complex models. Despite this performance, SWAT is under predicting stream flow peaks. A detailed investigation of important model components, has allowed us to identify some of the reasons for under predic- tion of stream flow peaks.

Kannan, N.; White, S. M.; Worrall, F.; Groves, S.

73

Rainfall field estimates for hydrological models  

NASA Astrophysics Data System (ADS)

The rainfall input in hydrological models concerns the mean area precipitation (MAP) values at a certain time resolution, which is required to be higher and higher in the rainfall-runoff modelling, but using space sampled data there is a limited MAP accuracy with respect to the involved time scale. Improved estimates of the rainfall field at small time intervals combine more accurate MAP values performed at a larger scale with the point time variability of data. The usual observation time scale for rain events is 1 h, with acceptable MAP errors, and according to the counting-box method applied in the case of the rainfall contour length there is a scale invariant below such a value. This paper suggests that an improved rainfall input may be obtained by transferring the shape of the hourly rain intensities to each hour in order to generate a finer time distribution of the MAP values, this being accepted if it leads to a better fitting of the simulated and observed hydrographs. This assumption is investigated by numerical experiments with a rainfall-runoff model at different catchment areas.

Zlate, Ionel

74

Evaluation of Community Land Model Hydrologic Predictions  

NASA Astrophysics Data System (ADS)

Confidence in representation and parameterization of land surface processes in coupled land-atmosphere models is strongly dependent on a diversity of opportunities for model testing, since such coupled models are usually intended for application in a wide range of conditions (regional models) or globally. Land surface models have been increasing in complexity over the past decade, which has increased the demands on data sets appropriate for model testing and evaluation. In this study, we compare the performance of two commonly used land surface schemes - the Variable Infiltration Capacity (VIC) and Community Land Model (CLM) with respect to their ability to reproduce observed water and energy fluxes in off-line tests for two large river basins with contrasting hydroclimatic conditions spanning the range from temperate continental to arctic, and for five point (column flux) sites spanning the range from tropical to arctic. The two large river basins are the Arkansas-Red in U.S. southern Great Plains, and the Torne-Kalix in northern Scandinavia. The column flux evaluations are for a tropical forest site at Reserva Jaru (ABRACOS) in Brazil, a prairie site (FIFE) near Manhattan, Kansas in the central U.S., a soybean site at Caumont (HAPEX-Monbilhy) in France, a meadow site at Cabauw in the Netherlands, and a small grassland catchment at Valday, Russia. The results indicate that VIC can reasonably well capture the land surface biophysical processes, while CLM is somewhat less successful. We suggest changes to the CLM parameterizations that would improve its general performance with respect to its representation of land surface hydrologic processes.

Li, K. Y.; Lettenmaier, D. P.; Bohn, T.; Delire, C.

2005-12-01

75

Evaluating the performance in the Swedish operational hydrological forecasting systems  

NASA Astrophysics Data System (ADS)

The production of hydrological forecasts generally involves the selection of model(s) and setup, calibration and initialization, verification and updating, generation and evaluation of forecasts. Although, field data are commonly used to calibrate and initiate hydrological models, technological advancements have allowed the use of additional information, i.e. remote sensing data and meteorological ensemble forecasts, to improve hydrological forecasts. However, the precision of hydrological forecasts is often subject to uncertainty related to various components of the production chain and data used. The Swedish Meteorological and Hydrological Institute (SMHI) operationally produces hydrological medium-range forecasts in Sweden using two modeling systems based on the HBV and S-HYPE hydrological models. The hydrological forecasts use both deterministic and ensemble (in total 51 ensemble members which are further reduced to 5 statistical members; 2, 25, 50, 75, 98% percentiles) meteorological forecasts from ECMWF to add information on the uncertainty of the predicted values. In this study, we evaluate the performance of the two operational hydrological forecasting systems and identify typical uncertainties in the forecasting production chain and ways to reduce them. In particular, we investigate the effect of autoregressive updating of the forecasted discharge, and of using the median of the ensemble instead of deterministic forecasts. Medium-range (10 days) hydrological forecasts across 71 selected indicator stations are used. The Kling-Gupta Efficiency and its decomposed terms are used to analyse the performance in different characteristics of the flow signal. Results show that the HBV and S-HYPE models with AR updating are both capable of producing adequate forecasts for a short lead time (1 to 2 days), and the performance steadily decreases in lead time. The autoregressive updating method can improve the performance of the two systems by 30 to 40% in terms of the KGE. This is mainly because the method has a significant impact on the improvement of discharge volume. S-HYPE seems to perform slightly better than HBV in the longer lead time, probably because the S-HYPE system is capable of updating the lake water level, which has an impact on the longer lead times. Moreover, the deterministic and ensemble HBV systems with AR updating perform fairly similar for all lead times. Keywords: Hydrological forecasting, S-HYPE, HBV, Operational production, Kling-Gupta Efficiency, Uncertainty.

Pechlivanidis, Ilias; Bosshard, Thomas; Spångmyr, Henrik; Lindström, Göran; Olsson, Jonas; Arheimer, Berit

2014-05-01

76

Mathematical Models of E-Antigen Mediated Immune Tolerance and Activation following Prenatal HBV Infection  

PubMed Central

We develop mathematical models for the role of hepatitis B e-antigen in creating immunological tolerance during hepatitis B virus infection and propose mechanisms for hepatitis B e-antigen clearance, subsequent emergence of a potent cellular immune response, and the effect of these on liver damage. We investigate the dynamics of virus-immune cells interactions, and derive parameter regimes that allow for viral persistence. We modify the model to account for mechanisms responsible for hepatitis B e-antigen loss, such as seroconversion and virus mutations that lead to emergence of cellular immune response to the mutant virus. Our models demonstrate that either seroconversion or mutations can induce immune activation and that instantaneous loss of e-antigen by either mechanism is associated with least liver damage and is therefore more beneficial for disease outcomes. PMID:22768303

Ciupe, Stanca M.; Hews, Sarah

2012-01-01

77

An open-source distributed mesoscale hydrologic model (mHM)  

NASA Astrophysics Data System (ADS)

The mesoscale hydrological model (mHM) is based on numerical approximations of dominant hydrological processes that have been tested in various hydrological models such as: HBV and VIC. In general, mHM simulates the following processes: canopy interception, snow accumulation and melting, soil moisture dynamics (n-horizons), infiltration and surface runoff, evapotranspiration, subsurface storage and discharge generation, deep percolation and baseflow, and discharge attenuation and flood routing. The main characteristic of mHM is the treatment of the sub-grid variability of input variables and model parameters which clearly distinguishes this model from existing precipitation-runoff models or land surface models. It uses a Multiscale Parameter Regionalization (MPR) to account for the sub-grid variability and to avoid continuous re-calibration. Effective model parameters are location and time dependent (e.g., soil porosity). They are estimated through upscaling operators that link sub-grid morphologic information (e.g., soil texture) with global transfer-function parameters, which, in turn, are found through multi-basin optimization. Global parameters estimated with the MPR technique are quasi-scale invariant and guarantee flux-matching across scales. mHM is an open source code, written in Fortran 2003 (standard), fully modular, with high computational efficiency, and parallelized. It is portable to multiple platforms (Linux, OS X, Windows) and includes a number of algorithms for sensitivity analysis, analysis of parameter uncertainty (MCMC), and optimization (DDS, SA, SCE). All simulated state variables and outputs can be stored as netCDF files for further analysis and visualization. mHM has been evaluated in all major river basins in Germany and over 80 US and 250 European river basins. The model efficiency (NSE) during validation at proxy locations is on average greater than 0.6. During last years, mHM had been used for number of hydrologic applications such as, for example, a) to investigate the influence of the antecedent soil moisture on extreme floods in Germany (2002 and 2013), b) for establishing benchmark agricultural drought events for Germany since 1950. A 60-year reconstruction of the daily mHM soil moisture fields over Germany at high resolution 4 × 4 km2 was used for this purpose, and c) to investigate the potential benefits of a high resolution modeling approach for the drought monitoring and forecasting system over Pan-EU. We invite the community to take advantage of this open-source code which is freely available (after nominal registration) at: http://www.ufz.de/index.php?en=31389.

Samaniego, Luis; Kumar, Rohini; Zink, Matthias; Thober, Stephan; Mai, Juliane; Cuntz, Matthias; Schäfer, David; Schrön, Martin; Musuuza, Jude; Prykhodko, Vladyslav; Dalmasso, Giovanni; Attinger, Sabine; Spieler, Diana; Rakovec, Oldrich; Craven, John; Langenberg, Ben

2014-05-01

78

A double continuum hydrological model for glacier applications  

NASA Astrophysics Data System (ADS)

The flow of glaciers and ice streams is strongly influenced by the presence of water at the interface between ice and bed. In this paper, a hydrological model evaluating the subglacial water pressure is developed with the final aim of estimating the sliding velocities of glaciers. The global model fully couples the subglacial hydrology and the ice dynamics through a water-dependent friction law. The hydrological part of the model follows a double continuum approach which relies on the use of porous layers to compute water heads in inefficient and efficient drainage systems. This method has the advantage of a relatively low computational cost that would allow its application to large ice bodies such as Greenland or Antarctica ice streams. The hydrological model has been implemented in the finite element code Elmer/Ice, which simultaneously computes the ice flow. Herein, we present an application to the Haut Glacier d'Arolla for which we have a large number of observations, making it well suited to the purpose of validating both the hydrology and ice flow model components. The selection of hydrological, under-determined parameters from a wide range of values is guided by comparison of the model results with available glacier observations. Once this selection has been performed, the coupling between subglacial hydrology and ice dynamics is undertaken throughout a melt season. Results indicate that this new modelling approach for subglacial hydrology is able to reproduce the broad temporal and spatial patterns of the observed subglacial hydrological system. Furthermore, the coupling with the ice dynamics shows good agreement with the observed spring speed-up.

de Fleurian, B.; Gagliardini, O.; Zwinger, T.; Durand, G.; Le Meur, E.; Mair, D.; Råback, P.

2014-01-01

79

Treatment of input uncertainty in hydrologic modeling: Doing hydrology backward with Markov chain Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

There is increasing consensus in the hydrologic literature that an appropriate framework for streamflow forecasting and simulation should include explicit recognition of forcing and parameter and model structural error. This paper presents a novel Markov chain Monte Carlo (MCMC) sampler, entitled differential evolution adaptive Metropolis (DREAM), that is especially designed to efficiently estimate the posterior probability density function of hydrologic model parameters in complex, high-dimensional sampling problems. This MCMC scheme adaptively updates the scale and orientation of the proposal distribution during sampling and maintains detailed balance and ergodicity. It is then demonstrated how DREAM can be used to analyze forcing data error during watershed model calibration using a five-parameter rainfall-runoff model with streamflow data from two different catchments. Explicit treatment of precipitation error during hydrologic model calibration not only results in prediction uncertainty bounds that are more appropriate but also significantly alters the posterior distribution of the watershed model parameters. This has significant implications for regionalization studies. The approach also provides important new ways to estimate areal average watershed precipitation, information that is of utmost importance for testing hydrologic theory, diagnosing structural errors in models, and appropriately benchmarking rainfall measurement devices.

Vrugt, Jasper A.; Ter Braak, Cajo J. F.; Clark, Martyn P.; Hyman, James M.; Robinson, Bruce A.

2008-12-01

80

Common Research Framework for Global Hydrology Utilizing Various Datasets and Hydrologic Models  

NASA Astrophysics Data System (ADS)

A flexible research framework is developed for common needs in global hydrological research. This framework consists of five components including input/output (I/O) interfaces, models, analyzers, and publishers. Backbone chassis of this framework is developed using the Python, because it provides functionalities to wrap and integrate other languages. Global hydrologic simulation needs various dataset such as model forcing data, parameter sets, and validation data, and all of them are distributed in different formats. Therefore, I/O interfaces are implemented to handle different dataset uniformly. They does not only support various data format including text, binary, network common data form (netCDF), gridded binary (GRIB), and GTool, but also provide presets for many field/satellite observational datasets. Model part provides modulized models and interface generators for external numerical models. Noah land surface model and Total Runoff Integrated Pathway (TRIP) are modulized, and helper interfaces to manage an environment of numerical simulation projects including atmospheric and hydrologic models. The analyzer part and publisher consists of many small snippets and utilities to manipulate data with graphical user interface and to publish data on web or so. For computational efficiency, most of base components are written in native compiler languages such as Fortran and C with a wrapping tool F2py, and the Python array calculation module Numpy and plotting module matplotlib are heavily used. This framework solves many difficulties dramatically reducing required time and effort to prepare simulation and process result in the research of global hydrology.

Kim, H.; Oki, T.; Kanae, S.; Seto, S.

2008-12-01

81

Future hydrological extremes: the uncertainty from multiple global climate and global hydrological models  

NASA Astrophysics Data System (ADS)

Projections of changes in the hydrological cycle from Global Hydrological Models (GHMs) driven by Global Climate Models (GCMs) are critical for understanding future occurrence of hydrological extremes. However, uncertainties remain large and need to be better assessed. In particular, recent studies have pointed to a considerable contribution of GHMs that can equal or outweigh the contribution of GCMs to uncertainty in hydrological projections. Using 6 GHMs and 5 GCMs from the ISI-MIP multi-model ensemble, this study aims: (i) to assess future changes in the frequency of both high and low flows at the global scale using control and future (RCP8.5) simulations by the 2080s, and (ii) to quantify, for both ends of the runoff spectrum, GCMs and GHMs contributions to uncertainty using a 2-way ANOVA. Increases are found in high flows for northern latitudes and in low flows for several hotspots. Globally, the largest source of uncertainty is associated with GCMs, but GHMs are the greatest source in snow dominated regions. More specifically, results vary depending on the runoff metric, the temporal (annual and seasonal) and regional scale of analysis. For instance, uncertainty contribution from GHMs is higher for low flows than it is for high flows, partly owing to the different processes driving the onset of the two phenomena (e.g. the more direct effect of the GCMs precipitation variability on high flows). This study provides a comprehensive synthesis of where future hydrological extremes are projected to increase and where the ensemble spread is owed to either GCMs or GHMs. Finally, our results underline the importance of using multiple GCMs and GHMs to envelope the overall uncertainty range and the need for improvements in modeling snowmelt and runoff processes to project future hydrological extremes.

Giuntoli, I.; Vidal, J.-P.; Prudhomme, C.; Hannah, D. M.

2015-01-01

82

Modelling the hydrology of the Greenland ice sheet   

E-print Network

This thesis aims to better understand the relationships between basal water pressure, friction, and sliding mechanisms at ice sheet scales. In particular, it develops a new subglacial hydrology model (Hydro) to explicitly ...

Karatay, Mehmet Rahmi

2011-06-28

83

Mapping Field Surface Soil Moisture for Hydrological Modeling  

Microsoft Academic Search

Soil moisture is a major control variable on hydrological processes both at the storm event scale and in the long term. The\\u000a aggregate effect on the mean water balance over an area can be quantified successfully using hydrological models. However,\\u000a determination of soil moisture distribution for semi or fully distributed models is difficult. In some types of landscape,\\u000a the distribution

Mustafa Tombul

2007-01-01

84

New insights for the hydrology of the Rhine based on the new generation climate models  

NASA Astrophysics Data System (ADS)

Decision makers base their choices of adaptation strategies on climate change projections and their associated hydrological consequences. New insights of climate change gained under the new generation of climate models belonging to the IPCC 5th assessment report may influence (the planning of) adaption measures and/or future expectations. In this study, hydrological impacts of climate change as projected under the new generation of climate models for the Rhine were assessed. Hereto we downscaled 31 General Circulation Models (GCMs), which were developed as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5), using an advanced Delta Change Method for the Rhine basin. Changes in mean monthly, maximum and minimum flows at Lobith were derived with the semi-distributed hydrological model HBV of the Rhine. The projected changes were compared to changes that were previously obtained in the trans-boundary project Rheinblick using eight CMIP3 GCMs and Regional Climate Models (RCMs) for emission scenario A1B. All eight selected CMIP3 models (scenario A1B) predicted for 2071-2100 a decrease in mean monthly flows between June and October. Similar decreases were found for some of the 31 CMIP5 models for Representative Concentration Pathways (RCPs) 4.5, 6.0 and 8.5. However, under each RCP, there were also models that projected an increase in mean flows between June and October and on average the decrease was smaller than for the eight CMIP3 models. For 2071-2100, also the mean annual minimum 7-days discharge decreased less in the CMIP5 model simulations than was projected in CMIP3. When assessing the response of mean monthly flows of the CMIP5 simulation with the CSIRO-Mk3-6-0 and HadGEM2-ES models with respect to initial conditions and RCPs, it was found that natural variability plays a dominant role in the near future (2021-2050), while changes in mean monthly flows are dominated by the radiative forcing in the far future (2071-2100). According to RCP 8.5 model simulations, the change in mean monthly flow from May to November may be half the change in mean monthly flow projected by RCP 4.5. From January to March, RCP 8.5 simulations projected higher changes in mean monthly flows than RCP 4.5 simulations. These new insights based on the CMIP5 simulations imply that for the Rhine, the mean and low flow extremes might not decrease as much in summer as was expected under CMIP3. Stresses on water availability during summer are therefore also less than expected from CMIP3.

Bouaziz, Laurène; Sperna Weiland, Frederiek; Beersma, Jules; Buiteveld, Hendrik

2014-05-01

85

Rapid Post Fire Hydrologic Watershed Assessment using the AGWA GIS -based Hydrologic Modeling Tool  

Microsoft Academic Search

Rapid post -fire watershed assessment to identify potential trouble spots for erosion and flooding can potentially aid land managers and Bu rned Area Emergency Rehabilitation (BAER) teams in deploying mitigation and rehabilitation resources. These decisions are inherently complex and spatial in nature and require a distributed hydrological modeling approach. The extensive data requirements an d the task of building input

D. C. Goodrich; H. Evan Canfield; I. Shea Burns; D. J. Semmens; S. N. Miller; M. Hernandez; L. R. Levick; D. P. Guertin; W. G. Kepner

86

Coupled Hydrological and Hydraulic Modeling for Flood Mapping  

NASA Astrophysics Data System (ADS)

The delineation of the flooded areas involves both hydrological and hydraulic modeling. Usually, the hydrological and hydraulic processes are separately treated. In the proposed methodology, the coupled modeling of the hydrological and hydraulic processes is used. The calibration and validation of the hydrological parameters is undertaken based on historical floods using the corresponding precipitations for the same period. The calibration process was more complicated in the presence of reservoirs, when not only the discharges downstream but also the water level in the reservoirs had to be accurately reproduced. The time step for precipitation is 1 hour, corresponding to the concentration time of the smallest catchments. The maximum annual precipitation for different time steps (1; 3; 6; 24 hours) were statistically processed and based on these results the cumulative rainfall curves and the synthetic hyetographs were derived. The rainfall duration is depending on the concentration time. Mike 11 with UHM module based on SCS model was used for coupled hydrological and hydraulic modeling. The coupled hydrological and hydraulic simulation for the scaled precipitation leads both at the computation of the components which contribute to the generation of the P% flood at the Hydrometric stations as well as to the determination of the discharge hydrograph along the main river. Based on these results the flood hazard maps were obtained using a DTM based on Lidar data. The methodology was applied for a river basin in Romania of 12500 km2.

Drobot, Radu; Draghia, Aurelian

2014-05-01

87

Adaptive Parameter Optimization of a Grid-based Conceptual Hydrological Model  

NASA Astrophysics Data System (ADS)

Any spatially explicit hydrological model at the mesoscale is a conceptual approximation of the hydrological cycle and its dominant process occurring at this scale. Manual-expert calibration of this type of models may become quite tedious---if not impossible---taking into account the enormous amount of data required by these kind of models and the intrinsic uncertainty of both the data (input-output) and the model structure. Additionally, the model should be able to reproduce well several process which are accounted by a number of predefined objectives. As a consequence, some degree of automatic calibration would be required to find "good" solutions, each one constituting a trade-off among all calibration criteria. In other words, it is very likely that a number of parameter sets fulfil the optimization criteria and thus can be considered a model solution. In this study, we dealt with two research questions: 1) How to assess the adequate level of model complexity so that model overparameterization is avoided? And, 2) How to find a good solution with a relatively low computational burden? In the present study, a grid-based conceptual hydrological model denoted as HBV-UFZ based on some of the original HBV concepts was employed. This model was driven by 12~h precipitation, temperature, and PET grids which are acquired either from satellite products or from data of meteorological stations. In the latter case, the data was interpolated with external drift Kriging. The first research question was addressed in this study with the implementation of nonlinear transfer functions that regionalize most model parameters as a function of other spatially distributed observables such as land cover (time dependent) and other time independent basin characteristics such as soil type, slope, aspect, geological formations among others. The second question was addressed with an adaptive constrained optimization algorithm based on a parallel implementation of simulated annealing (SA). The main difference with the standard SA is the parameter search routine which uses adaptive heuristic rules to improve its efficiency. These rules are based on the relative behavior of the efficiency criteria. The efficiency of the model is evaluated with the Nash-Sutcliffe efficiency coefficient (NS) and the RMSE obtained for various short and long term runoff characteristics such as daily flows; semiannual high and low flow characteristics such as total drought duration frequency of high flows; and annual specific discharge at various gauging stations. Additionally, the parameter search was constrained with the 95% confidence bands of the runoff characteristics mentioned above. The proposed method was calibrated in the Upper Neckar River basin covering an area of approximately 4000~km2 during the period from 1961 to 1993. The spatial and temporal resolutions used were a grid size of (1000 × 1000)~m and 12~h intervals respectively. The results of the study indicate significant improvement in model performance (e.g. Nash-Sutcliffe of various runoff characteristics ~ 0.8) and a significant reduction in computational burden of at least 25%.

Samaniego, L.; Kumar, R.; Attinger, S.

2007-12-01

88

Hydrologic Modeling Strategy for the Islamic Republic of Mauritania, Africa  

USGS Publications Warehouse

The government of Mauritania is interested in how to maintain hydrologic balance to ensure a long-term stable water supply for minerals-related, domestic, and other purposes. Because of the many complicating and competing natural and anthropogenic factors, hydrologists will perform quantitative analysis with specific objectives and relevant computer models in mind. Whereas various computer models are available for studying water-resource priorities, the success of these models to provide reliable predictions largely depends on adequacy of the model-calibration process. Predictive analysis helps us evaluate the accuracy and uncertainty associated with simulated dependent variables of our calibrated model. In this report, the hydrologic modeling process is reviewed and a strategy summarized for future Mauritanian hydrologic modeling studies.

Friedel, Michael J.

2008-01-01

89

Radar data bias correction implementing quantile mapping and investigation of its influence in a hydrological model  

NASA Astrophysics Data System (ADS)

Weather radar is an important source of data for estimating rainfall rate with relatively high temporal and spatial resolution covering large areas. Although weather radar provides fine temporal and spatial resolution data, it is subject to different sources of error. Beside casual problems associated with radar, e.g. clutter and attenuation, weather radar either underestimates or overestimates the rainfall amount. Additionally, time steps with strangely high values result in destroying the structure of time series derived from radar data. In order to estimate areal precipitation for hydrological analyses, radar data could be merged with rain gauge network data. The merging product quality is strongly dependent on radar data quality. The main purpose of this study is to illustrate a method for improving radar data quality and to investigate the influence of radar data quality on merging products by means of cross validation. Quantile mapping on the two sources of data, the radar and rain gauge network, is implemented in this study to improve the radar data quality. After correcting the radar data, considering rain gauge data as the truth, the data is implemented into a hydrological model, HBV-IWW, to investigate the influence of the different input sources regarding model performance. It has been observed that implementing quantile mapping improves radar data quality significantly. On the other hand, using radar data after correction not only improves interpolation performances but also reveals other possible applications like disaggregation of daily rainfall data into finer temporal resolutions. Beside radar data quality, there are other factors influencing the model performance like network density and the applied interpolation technique. The study area is a mesoscale catchment located in Lower Saxony, northern Germany.

Rabiei, Ehsan; Wallner, Markus; Haberlandt, Uwe

2014-05-01

90

Strategies for using remotely sensed data in hydrologic models  

NASA Technical Reports Server (NTRS)

Present and planned remote sensing capabilities were evaluated. The usefulness of six remote sensing capabilities (soil moisture, land cover, impervious area, areal extent of snow cover, areal extent of frozen ground, and water equivalent of the snow cover) with seven hydrologic models (API, CREAMS, NWSRFS, STORM, STANFORD, SSARR, and NWSRFS Snowmelt) were reviewed. The results indicate remote sensing information has only limited value for use with the hydrologic models in their present form. With minor modifications to the models the usefulness would be enhanced. Specific recommendations are made for incorporating snow covered area measurements in the NWSRFS Snowmelt model. Recommendations are also made for incorporating soil moisture measurements in NWSRFS. Suggestions are made for incorporating snow covered area, soil moisture, and others in STORM and SSARR. General characteristics of a hydrologic model needed to make maximum use of remotely sensed data are discussed. Suggested goals for improvements in remote sensing for use in models are also established.

Peck, E. L.; Keefer, T. N.; Johnson, E. R. (principal investigators)

1981-01-01

91

High Resolution Hydrologic Modeling: Challenges and Avenues for Development  

NASA Astrophysics Data System (ADS)

Hydrological processes are complex phenomena of continuous movement of water in different medium with different temporal and spatial scales. The interaction between surface and subsurface water is a basic feature of hydrological processes increasing uncertainties in predictions. Fully integrated surface-subsurface modeling is an approach to properly understand or predict the complex hydrological phenomena having tight interaction between two systems. Parameterization of soil medium is one of major uncertainty sources limiting availability of integrated modeling. To increase certainty of hydrological modeling, data assimilation can be used considering uncertainties in models, parameters, and observations. However, an estimation via DA(Date Assimilation) in high-dimensional and high nonlinear systems is still a challenging task, which will be a key solution for high resolution hydrological modeling. In this study, we propose a sequential data assimilation method for state-parameter estimation of a three-dimensional integrated surface-subsurface model. The applied model uses the finite volume discretizations on non-orthogonal grids to solve shallow water type diffusion wave equation in the surface flow and Richards' equation in the saturated-unsaturated subsurface flow system. A hybrid DA approach based on particle filtering and ensemble Kalman filtering is implemented to update uncertain soil parameters and state variables using discharge and moisture observations. Synthetic experiments are performed to demonstrate the proposed methodology.

An, H.; Noh, S.

2013-12-01

92

Models of atmosphere-ecosystem-hydrology interactions: Approaches and testing  

NASA Technical Reports Server (NTRS)

Interactions among the atmosphere, terrestrial ecosystems, and the hydrological cycle have been the subject of investigation for many years, although most of the research has had a regional focus. The topic is broad, including the effects of climate and hydrology on vegetation, the effects of vegetation on hydrology, the effects of the hydrological cycle on the atmosphere, and interactions of the cycles via material flux such as solutes and trace gases. The intent of this paper is to identify areas of critical uncertainty, discuss modeling approaches to resolving those problems, and then propose techniques for testing. I consider several interactions specifically to illustrate the range of problems. These areas are as follows: (1) cloud parameterizations and the land surface, (2) soil moisture, and (3) the terrestrial carbon cycle.

Schimel, David S.

1992-01-01

93

A spatial and temporal continuous surface-subsurface hydrologic model  

NASA Astrophysics Data System (ADS)

A hydrologic model integrating surface-subsurface processes was developed based on spatial and temporal continuity theory. The raster-based mass balance hydrologic model consists of several submodels which determine spatial and temporal patterns in precipitation, surface flow, infiltration, subsurface flow, and the linkages between these submodels. Model parameters and variables are derived directly or indirectly from satellite remote sensing data, topographic maps, soil maps, literature, and weather station data and are stored in a Geographic Information System (GIS) database used for visualization. Surface resolution of cells in the model is 20 m by 20 m (pixel resolution of the Systeme Probatoire d'Observation de la Terre (SPOT) satellite image) over a 2511 km2 study area around the Crazy Mountains, Alaska, a watershed on the Arctic Circle draining into the Yukon River. The outputs from this model illustrate the interaction of physical and biologic factors on the partitioning of hydrologic components in a complex landscape.

Xiao, Qing-Fu; Ustin, Susan L.; Wallender, Wesley W.

1996-12-01

94

A strategy for diagnosing and interpreting hydrological model nonstationarity  

NASA Astrophysics Data System (ADS)

paper presents a strategy for diagnosing and interpreting hydrological nonstationarity, aiming to improve hydrological models and their predictive ability under changing hydroclimatic conditions. The strategy consists of four elements: (i) detecting potential systematic errors in the calibration data; (ii) hypothesizing a set of "nonstationary" parameterizations of existing hydrological model structures, where one or more parameters vary in time as functions of selected covariates; (iii) trialing alternative stationary model structures to assess whether parameter nonstationarity can be reduced by modifying the model structure; and (iv) selecting one or more models for prediction. The Scott Creek catchment in South Australia and the lumped hydrological model GR4J are used to illustrate the strategy. Streamflow predictions improve significantly when the GR4J parameter describing the maximum capacity of the production store is allowed to vary in time as a combined function of: (i) an annual sinusoid; (ii) the previous 365 day rainfall and potential evapotranspiration; and (iii) a linear trend. This improvement provides strong evidence of model nonstationarity. Based on a range of hydrologically oriented diagnostics such as flow-duration curves, the GR4J model structure was modified by introducing an additional calibration parameter that controls recession behavior and by making actual evapotranspiration dependent only on catchment storage. Model comparison using an information-theoretic measure (the Akaike Information Criterion) and several hydrologically oriented diagnostics shows that the GR4J modifications clearly improve predictive performance in Scott Creek catchment. Based on a comparison of 22 versions of GR4J with different representations of nonstationarity and other modifications, the model selection approach applied in the exploratory period (used for parameter estimation) correctly identifies models that perform well in a much drier independent confirmatory period.

Westra, Seth; Thyer, Mark; Leonard, Michael; Kavetski, Dmitri; Lambert, Martin

2014-06-01

95

Integrated hydrological SVAT model for climate change studies in Denmark  

Microsoft Academic Search

In a major Danish funded research project (www.hyacints.dk) a coupling is being established between the HIRHAM regional climate model code from Danish Meteorological Institute and the MIKE SHE distributed hydrological model code from DHI. The linkage between those two codes is a soil vegetation atmosphere transfer scheme, which is a module of MIKE SHE. The coupled model will be established

M. Mollerup; J. Refsgaard; T. O. Sonnenborg

2010-01-01

96

Test plan for hydrologic modeling of protective barriers  

Microsoft Academic Search

Pacific Northwest Laboratory prepared this test plan for the Model Applications and Validation Task of the Hanford Protective Barriers Program, which is managed by Westinghouse Hanford Company. The objectives of this plan are to outline the conceptual hydrologic model of protective barriers, discuss the available computer codes, describe the interrelationships between the modeling task and the other tasks of the

Fayer

1990-01-01

97

Genetic Algorithm Optimization of Artificial Neural Networks for Hydrological Modelling  

Microsoft Academic Search

This paper will consider the case for genetic algorithm optimization in the development of an artificial neural network model. It will provide a methodological evaluation of reported investigations with respect to hydrological forecasting and prediction. The intention in such operations is to develop a superior modelling solution that will be: \\\\begin{itemize} more accurate in terms of output precision and model

R. J. Abrahart

2004-01-01

98

Analysis of Streamflow Predictive Uncertainty using Multiple Hydrologic Models in Climate Change Impact Study  

NASA Astrophysics Data System (ADS)

Based on the statistically downscaled outputs from 8 global climate model projections and 2 emission scenarios we assess the uncertainties associated with GCMs and hydrologic models by means of multi-modeling. As there is no conceivable reason that any hydrologic model is performing better under all circumstances, four hydrologic models are selected for the hydrologic impact study: the Sacramento Soil Moisture Accounting (SAC-SMA) model, Conceptual HYdrologic MODel (HYMOD), Thornthwaite-Mather model (TM) and the Precipitation Runoff Modeling System (PRMS). Three objective functions are adopted to calibrate each model. The hydrologic model simulations are combined using the Bayesian Model Averaging (BMA) method. This study shows that the application of the BMA in analyzing the models ensemble is useful in minimizing the uncertainty in selecting the hydrologic model selection. It is also concluded that the hydrologic model uncertainty is considerably smaller than GCM uncertainty, except during the dry season.

Yang, P.; Najafi, M.; Moradkhani, H.

2010-12-01

99

Integrated hydrological modelling of a managed coastal Mediterranean wetland (Rhone delta, France) Hydrology and Earth System Sciences, 7(1), 123131 (2003) EGU  

E-print Network

Integrated hydrological modelling of a managed coastal Mediterranean wetland (Rhone delta, France) 123 Hydrology and Earth System Sciences, 7(1), 123­131 (2003) © EGU Integrated hydrological modelling. This hydrosystem is subject to strong natural hydrological variability due to the combination of a Mediterranean

Paris-Sud XI, Université de

100

Satellite-derived potential evapotranspiration for distributed hydrologic runoff modeling  

NASA Astrophysics Data System (ADS)

Distributed models have the ability of incorporating spatially variable data, especially high resolution forcing inputs such as precipitation, temperature and evapotranspiration in hydrologic modeling. Use of distributed hydrologic models for operational streamflow prediction has been partially hindered by a lack of readily available, spatially explicit input observations. Potential evapotranspiration (PET), for example, is currently accounted for through PET input grids that are based on monthly climatological values. The goal of this study is to assess the use of satellite-based PET estimates that represent the temporal and spatial variability, as input to the National Weather Service (NWS) Hydrology Laboratory Research Distributed Hydrologic Model (HL-RDHM). Daily PET grids are generated for six watersheds in the upper Mississippi River basin using a method that applies only MODIS satellite-based observations and the Priestly Taylor formula (MODIS-PET). The use of MODIS-PET grids will be tested against the use of the current climatological PET grids for simulating basin discharge. Gridded surface temperature forcing data are derived by applying the inverse distance weighting spatial prediction method to point-based station observations from the Automated Surface Observing System (ASOS) and Automated Weather Observing System (AWOS). Precipitation data are obtained from the Climate Prediction Center's (CPC) Climatology-Calibrated Precipitation Analysis (CCPA). A-priori gridded parameters for the Sacramento Soil Moisture Accounting Model (SAC-SMA), Snow-17 model, and routing model are initially obtained from the Office of Hydrologic Development and further calibrated using an automated approach. The potential of the MODIS-PET to be used in an operational distributed modeling system will be assessed with the long-term goal of promoting research to operations transfers and advancing the science of hydrologic forecasting.

Spies, R. R.; Franz, K. J.; Bowman, A.; Hogue, T. S.; Kim, J.

2012-12-01

101

Merging Multiple Climate Model Forecasts for Seasonal Hydrologic Predictions  

NASA Astrophysics Data System (ADS)

Skillful seasonal hydrologic predictions are required in water resource management, preparation for drought and its impacts, energy planning, and many other related sectors. In this study, a seasonal hydrologic ensemble prediction system is developed and evaluated over the Eastern U.S., with focus on the Ohio River basin. The seasonal hydrologic prediction system utilizes a hydrologic model (in this case the Variable Infiltration Capacity model) as the central element for producing ensemble hydrologic predictions of soil moisture, snow and streamflow with lead times up to 6 months. The uniqueness of this forecast system is in the method for generating ensemble atmospheric forcings for the forecast period. It merges seasonal climate predictions from multiple climate models with observed climatology in a Bayesian framework such that the uncertainties related to the atmospheric forcings can be reduced and better quantified. This framework also downscales the climate model forecasts to scales appropriate for hydrologic prediction and uses a rank structure of selected historical forcings to ensure that generated ensembles of daily meteorological forcings have reasonable patterns in space and time. Three types of forecasts were performed in the study: those using information from NCEP's Climate Forecast System (CFS), those using information from CFS and the European Union funded multi-model prediction project called DEMETER, and those based the Extended Streamflow Prediction (ESP) approach. Forecasts (CFS, CFS+DEMETER and ESP) were made with the system for the summer periods (May to October) for 1981 - 1999, and represent forecast information from one climate model, eight climate models and none, respectively. The differences in forecast skills between CFS, CFS+DEMETER and ESP reflect the improvement with the new forecast method against the current hydrological operational approach, which is based on ESP. The forecast for the summer 1988 shows very promising skill in precipitation, soil moisture and streamflow forecast over the Ohio river basin, especially with the CFS+DEMETER forecast. The evaluation over all 19 summer forecasts shows significant skill improvement with the new multi-model method during the first two months of the forecasts. The improvement is marginal to moderate when only CFS forecast is used. This study validates the approach of using seasonal climate predictions from dynamic climate models in hydrological predictions. It also shows the need for international collaborations to develop multi-model seasonal predictions.

Luo, L.; Wood, E. F.; Pan, M.; Li, H.

2007-12-01

102

An integrated modeling environment within the CUAHSI Hydrologic Information System  

NASA Astrophysics Data System (ADS)

Modeling complicated hydrologic systems often requires the integration of disparate data and models. The CUAHSI Hydrologic Information System targets the problem of integrating data by using a service-oriented architecture and data exchange standards to make heterogeneous databases appear to an end user as a single data resource. Similar integration problems exist with hydrologic models. If one wishes to analyze a problem that requires logic within multiple models, the challenge becomes how to couple those models so that they are able to exchange data during model runtime. A solution to this problem has been proposed through the Open Modeling Interface (OpenMI) standard for integrating hydrologic models. Building from the OpenMI standard, we have created a modeling environment within the CUAHSI Hydrologic Information System HydroDesktop application for performing integrated modeling. The modeling environment, which we have named HydroModeler, allows for loose coupling of model, analysis, and data components. We provide components for reading and writing data to the HydroDesktop database, as well as a number of example model configurations for demonstration and education purposes. An advantage of adopting the OpenMI standard is that it enables one to include OpenMI compliant models written by other groups within HydroModeler and, likewise, components written specifically for HydroModeler — e.g. the HydroDesktop database writer and reader components - can be used within other OpenMI-compliant modeling environments. Through the process of building HydroModeler we have investigated topics including (1) creating process-level OpenMI components, (2) modeling component configurations with bi-directional links (feedback loops), and (3) the process for re-scaling data exchanges between spatially and temporally misaligned data components “on-the-fly” during model configuration runs. These are general challenges faced by many modeling systems that adopt a loose coupling paradigm, and we will present how such issues can be addressed within HydroModeler using OpenMI. Our future plans are to continue to grow the number of model components within the environment, focusing specifically on decomposing large watershed models into functional components that can then be linked together to simulate hydrologic systems and address specific science or management questions.

Goodall, J. L.; Castronova, A. M.; Elag, M.; Ercan, M. B.

2010-12-01

103

A physically-based Distributed Hydrologic Model for Tropical Catchments  

NASA Astrophysics Data System (ADS)

Hydrological models are mathematical formulations intended to represent observed hydrological processes in a watershed. Simulated watersheds in turn vary in their nature based on their geographic location, altitude, climatic variables and geology and soil formation. Due to these variations, available hydrologic models vary in process formulation, spatial and temporal resolution and data demand. Many tropical watersheds are characterized by extensive and persistent biological activity and a large amount of rain. The Agua Salud catchments located within the Panama Canal Watershed, Panama, are such catchments identified by steep rolling topography, deep soils derived from weathered bedrock, and limited exposed bedrock. Tropical soils are highly affected by soil cracks, decayed tree roots and earthworm burrows forming a network of preferential flow paths that drain to a perched water table, which forms at a depth where the vertical hydraulic conductivity is significantly reduced near the bottom of the bioturbation layer. We have developed a physics-based, spatially distributed, multi-layered hydrologic model to simulate the dominant processes in these tropical watersheds. The model incorporates the major flow processes including overland flow, channel flow, matrix and non-Richards film flow infiltration, lateral downslope saturated matrix and non-Darcian pipe flow in the bioturbation layer, and deep saturated groundwater flow. Emphasis is given to the modeling of subsurface unsaturated zone soil moisture dynamics and the saturated preferential lateral flow from the network of macrospores. Preliminary results indicate that the model has the capability to simulate the complex hydrological processes in the catchment and will be a useful tool in the ongoing comprehensive ecohydrological studies in tropical catchments, and help improve our understanding of the hydrological effects of deforestation and aforestation.

Abebe, N. A.; Ogden, F. L.

2010-12-01

104

The Use of Simulation Models in Teaching Geomorphology and Hydrology.  

ERIC Educational Resources Information Center

Learning about the physical environment from computer simulation models is discussed in terms of three stages: exploration, experimentation, and calibration. Discusses the effective use of models and presents two computer simulations written in BBC BASIC, STORFLO (for catchment hydrology) and SLOPEK (for hillslope evolution). (Author/GEA)

Kirkby, Mike; Naden, Pam

1988-01-01

105

Ensemble catchment hydrological modelling for climate change impact analysis  

NASA Astrophysics Data System (ADS)

It is vital to investigate how the hydrological model structure affects the climate change impact given that future changes not in the range for which the models were calibrated or validated are likely. Thus an ensemble modelling approach which involves a diversity of models with different structures such as spatial resolutions and process descriptions is crucial. The ensemble modelling approach was applied to a set of models: from the lumped conceptual models NAM, PDM and VHM, an intermediate detailed and distributed model WetSpa, to the highly detailed and fully distributed model MIKE-SHE. Explicit focus was given to the high and low flow extremes. All models were calibrated for sub flows and quick flows derived from rainfall and potential evapotranspiration (ETo) time series. In general, all models were able to produce reliable estimates of the flow regimes under the current climate for extreme peak and low flows. An intercomparison of the low and high flow changes under changed climatic conditions was made using climate scenarios tailored for extremes. Tailoring was important for two reasons. First, since the use of many scenarios was not feasible it was necessary to construct few scenarios that would reasonably represent the range of extreme impacts. Second, scenarios would be more informative as changes in high and low flows would be easily traced to changes of ETo and rainfall; the tailored scenarios are constructed using seasonal changes that are defined using different levels of magnitude (high, mean and low) for rainfall and ETo. After simulation of these climate scenarios in the five hydrological models, close agreement was found among the models. The different models predicted similar range of peak flow changes. For the low flows, however, the differences in the projected impact range by different hydrological models was larger, particularly for the drier scenarios. This suggests that the hydrological model structure is critical in low flow predictions, more than in high flow conditions. Hence, the mechanism of the slow flow component simulation requires further attention. It is concluded that a multi-model ensemble approach where different plausible model structures are applied, is extremely useful. It improves the reliability of climate change impact results and allows decision making to be based on uncertainty assessment that includes model structure related uncertainties. References: Ntegeka, V., Baguis, P., Roulin, E., Willems, P., 2014. Developing tailored climate change scenarios for hydrological impact assessments. Journal of Hydrology, 508C, 307-321 Vansteenkiste, Th., Tavakoli, M., Ntegeka, V., Willems, P., De Smedt, F., Batelaan, O., 2013. Climate change impact on river flows and catchment hydrology: a comparison of two spatially distributed models. Hydrological Processes, 27(25), 3649-3662. Vansteenkiste, Th., Tavakoli, M., Ntegeka, V., Van Steenbergen, N., De Smedt, F., Batelaan, O., Pereira, F., Willems, P., 2014. Intercomparison of five lumped and distributed models for catchment runoff and extreme flow simulation. Journal of Hydrology, in press. Vansteenkiste, Th., Tavakoli, M., Ntegeka, V., De Smedt, F., Batelaan, O., Pereira, F., Willems, P., 2014. Intercomparison of climate scenario impact predictions by a lumped and distributed model ensemble. Journal of Hydrology, in revision.

Vansteenkiste, Thomas; Ntegeka, Victor; Willems, Patrick

2014-05-01

106

Modeller subjectivity and calibration impacts on hydrological model applications: an event-based comparison for a road-adjacent catchment in south-east Norway.  

PubMed

Identifying a 'best' performing hydrologic model in a practical sense is difficult due to the potential influences of modeller subjectivity on, for example, calibration procedure and parameter selection. This is especially true for model applications at the event scale where the prevailing catchment conditions can have a strong impact on apparent model performance and suitability. In this study, two lumped models (CoupModel and HBV) and two physically-based distributed models (LISEM and MIKE SHE) were applied to a small catchment upstream of a road in south-eastern Norway. All models were calibrated to a single event representing typical winter conditions in the region and then applied to various other winter events to investigate the potential impact of calibration period and methodology on model performance. Peak flow and event-based hydrographs were simulated differently by all models leading to differences in apparent model performance under this application. In this case-study, the lumped models appeared to be better suited for hydrological events that differed from the calibration event (i.e., events when runoff was generated from rain on non-frozen soils rather than from rain and snowmelt on frozen soil) while the more physical-based approaches appeared better suited during snowmelt and frozen soil conditions more consistent with the event-specific calibration. This was due to the combination of variations in subsurface conditions over the eight events considered, the subsequent ability of the models to represent the impact of the conditions (particularly when subsurface conditions varied greatly from the calibration event), and the different approaches adopted to calibrate the models. These results indicate that hydrologic models may not only need to be selected on a case-by-case basis but also have their performance evaluated on an application-by-application basis since how a model is applied can be equally important as inherent model structure. PMID:25262294

Kalantari, Zahra; Lyon, Steve W; Jansson, Per-Erik; Stolte, Jannes; French, Helen K; Folkeson, Lennart; Sassner, Mona

2015-01-01

107

Integrating Geophysics, Geology, and Hydrology for Enhanced Hydrogeological Modeling  

NASA Astrophysics Data System (ADS)

Geophysical measurements are important for providing information on the geological structure to hydrological models. Regional scale surveys, where several watersheds are mapped at the same time using helicopter borne transient electromagnetic, results in a geophysical model with a very high lateral and vertical resolution of the geological layers. However, there is a bottleneck when it comes to integrating the information from the geophysical models into the hydrological model. This transformation is difficult, because there is not a simple relationship between the hydraulic conductivity needed for the hydrological model and the electrical conductivity measured by the geophysics. In 2012 the Danish Council for Strategic Research has funded a large research project focusing on the problem of integrating geophysical models into hydrological models. The project involves a number of Danish research institutions, consulting companies, a water supply company, as well as foreign partners, USGS (USA), TNO (Holland) and CSIRO (Australia). In the project we will: 1. Use statistical methods to describe the spatial correlation between the geophysical and the lithological/hydrological data; 2. Develop semi-automatic or automatic methods for transforming spatially sampled geophysical data into geological- and/or groundwater-model parameter fields; 3. Develop an inversion method for large-scale geophysical surveys in which the model space is concordant with the hydrological model space 4. Demonstrate the benefits of spatially distributed geophysical data for informing and updating groundwater models and increasing the predictive power of management scenarios. 5. Develop a new receiver system for Magnetic Resonance Sounding data and further enhance the resolution capability of data from the SkyTEM system. 6. In test areas in Denmark, Holland, USA and Australia we will use data from existing airborne geophysical data, hydrological and geological data and also collect new airborne data, MRS surface and downhole data, and pump test data. The project is still in a startup phase but we already have results from two existing algorithms. The first one is an algorithm making a full joint inversion of Magnetic Resonance Sounding (MRS) data, Transient Electromagnetic Data (TEM) and pump test data. The second one is an algorithm using geostatistic and linear inverse theory to link boreholes categorized into clay and sand sequences together with electrical resistivities measured in spatially distributed soundings resulting in 3D models of clay and sand. We will present the HyGEM project and show results from the first two algorithms developed in the project.

Auken, E.

2012-12-01

108

Recession-based hydrological models for estimating low flows in ungauged catchments in the Himalayas Hydrology and Earth System Sciences, 8(5), 891902 (2004) EGU  

E-print Network

Recession-based hydrological models for estimating low flows in ungauged catchments in the Himalayas 891 Hydrology and Earth System Sciences, 8(5), 891902 (2004) © EGU Recession-based hydrological.R. Young1 and S.R. Kansakar2 1 Centre for Ecology and Hydrology,Wallingford, Oxfordshire, OX10 8BB, UK 2

Paris-Sud XI, Université de

109

Data assimilation of GRACE terrestrial water storage estimates into a regional hydrological model of the Rhine River basin  

NASA Astrophysics Data System (ADS)

Terrestrial water storage (TWS) can be defined as an integrated measure of surface water, soil moisture, snow water, and groundwater. TWS data is valuable for water resources management and hydrology. The ability to simulate realistic TWS is essential for understanding past hydrological events and predicting future changes of the hydrological cycle. Inadequacies in physics, deficiencies in land characteristics and uncertainties in meteorological data commonly limit the performance of hydrological models in estimating TWS. In this study, we investigated the benefits of assimilating TWS derived from the Gravity Recovery And Climate Experiment (GRACE) into the Wflow HBV-96 model using the Ensemble Kalman Filter (EnKF). Since hydrological model parameters are often uncertain over a large part of the Earth, we investigated the impact of GRACE assimilation in different model scenarios representing different degrees of data availability. Four case studies were considered comparing calibrated and non-calibrated model parameters and local and global forcing data. The chosen study area is the Rhine River basin. Our results were validated using in-situ stream gauge data. In all scenarios, the temporal signatures of the averaged TWS are similar after assimilating GRACE while the spatial distribution is heavily influenced by the model parameters and input data as well as their uncertainties. Assimilation using the EnKF reduced the standard deviation at every updating stage, resulting in lower standard deviations than the model or the observations alone. Discrepancies between the local and global precipitation products had a significant impact on discharge estimates. For instance, when the global forcing data were used, discharge was drastically overestimated when spurious heavy rainfall occurred during the winter. Based on the correlation coefficient, Nash-Sutcliffe coefficient (NS), and root-mean-square error (RMSE) computed between the estimated and measured discharges at 13 gauge stations, we concluded that GRACE assimilation slightly improves the model performance when the model is well calibrated (calibrated parameters with local forcing data). More importantly, the improvement observed for the non-calibrated model (non-calibrated parameters with global forcing data), suggests that the impact of GRACE assimilation may be more significant in data-sparse regions.

Tangdamrongsub, Natthachet; Steele-Dunne, Susan; Gunter, Brian C.; Widiastuti, Endang; Weerts, Albrecht; Ditmar, Pavel; Tsompanopoulos, Efstratios

2014-05-01

110

Identification of the HYPE hydrological model over the Indian subcontinent  

NASA Astrophysics Data System (ADS)

Large-scale hydrological modelling has the potential to encompass many river basins, cross regional and international boundaries and represent a number of different geophysical and climatic zones. However the performance of this type of model is subject to several sources of uncertainty/error which may be caused by, among others, the imperfectness of driving inputs, i.e. regional and global databases. This uncertainty further leads to wrong model parameterisation and incomplete process understanding. Data assimilation aims to utilize both hydrological process knowledge (as embodied in a hydrologic model) and information that can be gained from observations; hence information from model predictions and observations is synergistically used to improve performance. This study presents a methodology, drawn on experience from modelling with the HYPE model in the Indian subcontinent (covering a modelled area of 4.9 million km2), to enhance identification of highly parameterised large-scale hydrological models. The model was set up using available large-scale datasets on topography, land use, soil, precipitation, temperature, lakes, reservoirs, crop types, irrigation, evaporation, snow and discharge. A stepwise automatic calibration is carried out to avoid, to a certain extent, errors incurring in some model processes and being compensated by introducing errors in other parts of the model. In addition, information from remote sensing data is assimilated in the model to drive identification of parameters that control the spatial distribution of potential evapotranspiration. Results show that despite the strong hydro-climatic gradient over the domain, the model can adequately describe the hydrological process in the Indian subcontinent. Overall, the median Kling-Gupta Efficiency (KGE) increased from 0.08 to 0.64 during the calibration process using 43 stations of monthly discharge series over the period 1971 to 1979. Finally, decomposition of the KGE (i.e. into terms describing agreement in correlation, bias and variability between observed and modelled streamflow series) allowed a thorough understanding of model inadequacies. Keywords Large-scale hydrological modelling, HYPE, model identification, Kling-Gupta Efficiency, remote sensing, India

Pechlivanidis, Ilias; Gustafsson, David; Arheimer, Berit

2014-05-01

111

Integration of GRACE mass variations into a global hydrological model  

NASA Astrophysics Data System (ADS)

Time-variable gravity data of the GRACE (Gravity Recovery And Climate Experiment) satellite mission provide global information on temporal variations of continental water storage. In this study, we incorporate GRACE data for the first time directly into the tuning process of a global hydrological model to improve simulations of the continental water cycle. For the WaterGAP Global Hydrology Model (WGHM), we adopt a multi-objective calibration framework to constrain model predictions by both measured river discharge and water storage variations from GRACE and illustrate it on the example of three large river basins: Amazon, Mississippi and Congo. The approach leads to improved simulation results with regard to both objectives. In case of monthly total water storage variations we obtained a RMSE reduction of about 25 mm for the Amazon, 6 mm for the Mississippi and 1 mm for the Congo river basin. The results highlight the valuable nature of GRACE data when merged into large-scale hydrological modeling. Furthermore, they reveal the utility of the multi-objective calibration framework for the integration of remote sensing data into hydrological models.

Werth, S.; Güntner, A.; Petrovic, S.; Schmidt, R.

2009-01-01

112

Strategies to eliminate HBV infection  

PubMed Central

Chronic HBV infection is a major public health concern affecting over 240 million people worldwide. Although suppression of HBV replication is achieved in the majority of patients with currently available newer antivirals, discontinuation of therapy prior to hepatitis B surface antigen loss or seroconversion is associated with relapse of HBV in the majority of cases. Thus, new therapeutic modalities are needed to achieve eradication of the virus from chronically infected patients in the absence of therapy. The basis of HBV persistence includes viral and host factors. Here, we review novel strategies to achieve sustained cure or elimination of HBV. The novel approaches include targeting the viral and or host factors required for viral persistence, and novel immune-based therapies, including therapeutic vaccines. PMID:25309617

Kapoor, Rama; Kottilil, Shyam

2014-01-01

113

EVALUATION OF HYDROLOGIC MODELS IN THE DESIGN OF STABLE LANDFILL COVERS  

EPA Science Inventory

The study evaluates the utility of two hydrologic models in designing stable landfill cover systems. The models evaluated were HELP (Hydrologic Evaluation of Landfill Performance) and CREAMS (Chemicals, Runoff, and Erosion from Agricultural Management Systems). Studies of paramet...

114

Reducing equifinality of hydrological models by integrating Functional Streamflow Disaggregation  

NASA Astrophysics Data System (ADS)

A universal problem of the calibration of hydrological models is the equifinality of different parameter sets derived from the calibration of models against total runoff values. This is an intrinsic problem stemming from the quality of the calibration data and the simplified process representation by the model. However, discharge data contains additional information which can be extracted by signal processing methods. An analysis specifically developed for the disaggregation of runoff time series into flow components is the Functional Streamflow Disaggregation (FSD; Carl & Behrendt, 2008). This method is used in the calibration of an implementation of the hydrological model SWIM in a medium sized watershed in Thailand. FSD is applied to disaggregate the discharge time series into three flow components which are interpreted as base flow, inter-flow and surface runoff. In addition to total runoff, the model is calibrated against these three components in a modified GLUE analysis, with the aim to identify structural model deficiencies, assess the internal process representation and to tackle equifinality. We developed a model dependent (MDA) approach calibrating the model runoff components against the FSD components, and a model independent (MIA) approach comparing the FSD of the model results and the FSD of calibration data. The results indicate, that the decomposition provides valuable information for the calibration. Particularly MDA highlights and discards a number of standard GLUE behavioural models underestimating the contribution of soil water to river discharge. Both, MDA and MIA yield to a reduction of the parameter ranges by a factor up to 3 in comparison to standard GLUE. Based on these results, we conclude that the developed calibration approach is able to reduce the equifinality of hydrological model parameterizations. The effect on the uncertainty of the model predictions is strongest by applying MDA and shows only minor reductions for MIA. Besides further validation of FSD, the next steps include an extension of the study to different catchments and other hydrological models with a similar structure.

Lüdtke, Stefan; Apel, Heiko; Nied, Manuela; Carl, Peter; Merz, Bruno

2014-05-01

115

Hydrological responses to dynamically and statistically downscaled climate model output  

Microsoft Academic Search

Daily rainfall and surface temperature series were simulated for the Animas River basin, Colorado using dynamically and statistically downscaled output from the National Center for Environmental Prediction\\/ National Center for Atmospheric Research (NCEP\\/NCAR) re-analysis. A distributed hydrological model was then applied to the downscaled data. Relative to raw NCEP output, downscaled climate variables provided more realistic simulations of basin scale

Robert L. Wilby; Lauren E. Hay; William J. Gutowski Jr.; Raymond W. Arritt; Eugene S. Takle; Zaitao Pan; George H. Leavesley; Martyn P. Clark

2000-01-01

116

Rangeland Hydrology and Erosion Model (RHEM) for ESD  

Technology Transfer Automated Retrieval System (TEKTRAN)

The USDA-Natural Resources Conservation Service (NRCS) is currently engaged in updating and writing new ecological Site Descriptions (ESD’s). New and updated information about physiographic, soil, climate, and water features; plant communities—including “state and transition models”; and hydrology ...

117

A two-layer model of soil hydrology  

Microsoft Academic Search

A two-layer model of soil hydrology is developed for applications where only limited computer time and complexity are allowed. Volumetric soil water is computed in a thin upper layer for use in calculation of surface evaporation. Storage of water is computed for an underlying deeper layer.

L. Mahrt; H. Pan

1984-01-01

118

Green roof hydrologic performance and modeling: a review.  

PubMed

Green roofs reduce runoff from impervious surfaces in urban development. This paper reviews the technical literature on green roof hydrology. Laboratory experiments and field measurements have shown that green roofs can reduce stormwater runoff volume by 30 to 86%, reduce peak flow rate by 22 to 93% and delay the peak flow by 0 to 30 min and thereby decrease pollution, flooding and erosion during precipitation events. However, the effectiveness can vary substantially due to design characteristics making performance predictions difficult. Evaluation of the most recently published study findings indicates that the major factors affecting green roof hydrology are precipitation volume, precipitation dynamics, antecedent conditions, growth medium, plant species, and roof slope. This paper also evaluates the computer models commonly used to simulate hydrologic processes for green roofs, including stormwater management model, soil water atmosphere and plant, SWMS-2D, HYDRUS, and other models that are shown to be effective for predicting precipitation response and economic benefits. The review findings indicate that green roofs are effective for reduction of runoff volume and peak flow, and delay of peak flow, however, no tool or model is available to predict expected performance for any given anticipated system based on design parameters that directly affect green roof hydrology. PMID:24569270

Li, Yanling; Babcock, Roger W

2014-01-01

119

Hydrological modelling in a "big data" era: a proof of concept of hydrological models as web services  

NASA Astrophysics Data System (ADS)

Dealing with the massive increase in global data availability of all sorts is increasingly being known as "big data" science. Indeed, largely leveraged by the internet, a new resource of data sets emerges that are so large and heterogeneous that they become awkward to work with. New algorithms, methods and models are needed to filter such data to find trends, test hypotheses, make predictions and quantify uncertainties. As a considerable share of the data relate to environmental processes (e.g., satellite images, distributed sensor networks), this evolution provides exciting challenges for environmental sciences, and hydrology in particular. Web-enabled models are a promising approach to process large and distributed data sets, and to provide tailored products for a variety of end-users. It will also allow hydrological models to be used as building blocks in larger earth system simulation systems. However, in order to do so we need to reconsider the ways that hydrological models are built, results are made available, and uncertainties are quantified. We present the results of an experimental proof of concept of a hydrological modelling web-service to process heterogeneous hydrological data sets. The hydrological model itself consists of a set of conceptual model routines implemented with on a common platform. This framework is linked to global and local data sets through web standards provided by the Open Geospatial Consortium, as well as to a web interface that enables an end-user to request stream flow simulations from a self-defined location. In essence, the proof-of-concept can be seen as an implementation of the "Models of Everywhere" concept introduced by Beven in 2007. Although the setup is operational and effectively simulates stream flow, we identify several bottlenecks for optimal hydrological simulation in a web-context. The major challenges we identify are related to (1) model selection; (2) uncertainty quantification, and (3) user interaction and scenario analysis. Model selection is inherent to hydrological modelling, because of the large spatial and temporal variability of processes, which inhibits the use of one optimal model structure. However, in a web context it becomes paramount that such selection is automatic, yet objective and transparent. Similarly, uncertainty quantification is a mainstream practice in hydrological modelling, but in a web-context uncertainty analysis face unprecedented challenges in terms of tracking uncertainties throughout a possibly geographically distributed workflow, as well as dealing with an extreme heterogeneity of data availability. Lastly, the ability of end-users to interact directly with hydrological models poses specific challenges in terms of mapping user scenarios (e.g., a scenario of land-use change) into the model parameter space for prediction and uncertainty quantification. The setup has been used in several scientific experiments, including the large-scale UK consortium project on an Environmental Virtual Observatory pilot.

Buytaert, Wouter; Vitolo, Claudia

2013-04-01

120

The application of remote sensing to the development and formulation of hydrologic planning models  

NASA Technical Reports Server (NTRS)

The development of a remote sensing model and its efficiency in determining parameters of hydrologic models are reviewed. Procedures for extracting hydrologic data from LANDSAT imagery, and the visual analysis of composite imagery are presented. A hydrologic planning model is developed and applied to determine seasonal variations in watershed conditions. The transfer of this technology to a user community and contract arrangements are discussed.

Fowler, T. R.; Castruccio, P. A.; Loats, H. L., Jr.

1977-01-01

121

Hydrologic Modeling with Arc Hydro Tools 1 Copyright 2007 ESRI. All rights reserved. Arc Hydro  

E-print Network

Hydrologic Modeling with Arc Hydro Tools 1 Copyright © 2007 ESRI. All rights reserved. Arc Hydro Dartiguenave, ESRI inc. cdartiguenave@esri.com #12;Hydrologic Modeling with Arc Hydro Tools 2 2Arc Hydro and application development #12;Hydrologic Modeling with Arc Hydro Tools 3 3Arc HydroCopyright © 2007 ESRI. All

Kane, Andrew S.

122

Modeling winter hydrological processes under differing climatic conditions: Modifying WEPP  

NASA Astrophysics Data System (ADS)

Water erosion is a serious and continuous environmental problem worldwide. In cold regions, soil freeze and thaw has great impacts on infiltration and erosion. Rain or snowmelt on a thawing soil can cause severe water erosion. Of equal importance is snow accumulation and snowmelt, which can be the predominant hydrological process in areas of mid- to high latitudes and forested watersheds. Modelers must properly simulate winter processes to adequately represent the overall hydrological outcome and sediment and chemical transport in these areas. Modeling winter hydrology is presently lacking in water erosion models. Most of these models are based on the functional Universal Soil Loss Equation (USLE) or its revised forms, e.g., Revised USLE (RUSLE). In RUSLE a seasonally variable soil erodibility factor (K) was used to account for the effects of frozen and thawing soil. Yet the use of this factor requires observation data for calibration, and such a simplified approach cannot represent the complicated transient freeze-thaw processes and their impacts on surface runoff and erosion. The Water Erosion Prediction Project (WEPP) watershed model, a physically-based erosion prediction software developed by the USDA-ARS, has seen numerous applications within and outside the US. WEPP simulates winter processes, including snow accumulation, snowmelt, and soil freeze-thaw, using an approach based on mass and energy conservation. However, previous studies showed the inadequacy of the winter routines in the WEPP model. Therefore, the objectives of this study were: (1) To adapt a modeling approach for winter hydrology based on mass and energy conservation, and to implement this approach into a physically-oriented hydrological model, such as WEPP; and (2) To assess this modeling approach through case applications to different geographic conditions. A new winter routine was developed and its performance was evaluated by incorporating it into WEPP (v2008.9) and then applying WEPP to four study sites at different spatial scales under different climatic conditions, including experimental plots in Pullman, WA and Morris, MN, two agricultural drainages in Pendleton, OR, and a forest watershed in Mica Creek, ID. The model applications showed promising results, indicating adequacy of the mass- and energy-balance-based approach for winter hydrology simulation.

Dun, Shuhui

123

Vegetation Dynamics And Soil Moisture: Consequences For Hydrologic Modeling  

NASA Astrophysics Data System (ADS)

Current global population growth and economical development accelerates land cover conversion in many parts of the world. Introducing non-native species and woody species encroachment, with different water demands, can affect the partitioning of hydrological fluxes. The impacts on the hydrologic cycle at local to regional scales are poorly understood. The present study investigates the hydrologic implications of land use conversion from native vegetation to rubber. We first compare the vegetation dynamics of rubber (Hevea brasiliensis), a non- native specie in Southeast Asia, to the other main vegetation types in the study area. The experimental catchment, Nam Ken (69km 2), is located in the Xishuangbanna Prefecture (21 °N, 100 °E), in the south of Yunnan province in South China. From 2005 to 2006, we collected continuous records of 2 m deep soil moisture profiles in four different land covers (tea, secondary forest, grassland and rubber), and measured surface radiation in tea and rubber canopies. Our observations show that root water uptake by rubber during the dry season is controlled by the change of day-length, whereas water demand of the native vegetation starts with the arrival of the first monsoon rainfall. The different root water uptake dynamics of rubber result in distinct depletion of deeper layer soil moisture. Traditional evapotranspiration and soil moisture models are unable to simulate this specific behavior, thus a different conceptual model is needed to predict hydrologic changes due to land use conversion in the area.

Guardiola-Claramonte, M.; Troch, P. A.

2007-12-01

124

A distributed hydrology-vegetation model for complex terrain  

Microsoft Academic Search

A distributed hydrology-vegetation model is described that includes canopy interception, evaporation, transpiration, and snow accumulation and melt, as well as runoff generation via the saturation excess mechanisms. Digital elevation data are used to model topographic controls on incoming solar radiation, air temperature, precipitation, and downslope water movement. Canopy evapotranspiration is represented via a two-layer Penman-Monteith formulation that incorporates local net

Mark S. Wigmosta; D. P. Lettenmaier; L. W. Vail

1994-01-01

125

Utilization of remote sensing observations in hydrologic models  

NASA Technical Reports Server (NTRS)

Most of the remote sensing related work in hydrologic modeling has centered on modifying existing models to take advantage of the capabilities of new sensor techniques. There has been enough success with this approach to insure that remote sensing is a powerful tool in modeling the watershed processes. Unfortunately, many of the models in use were designed without recognizing the growth of remote sensing technology. Thus, their parameters were selected to be map or field crew definable. It is believed that the real benefits will come through the evolution of new models having new parameters that are developed specifically to take advantage of our capabilities in remote sensing. The ability to define hydrologically active areas could have a significant impact. The ability to define soil moisture and the evolution of new techniques to estimate evoportransportation could significantly modify our approach to hydrologic modeling. Still, without a major educational effort to develop an understanding of the techniques used to extract parameter estimates from remote sensing data, the potential offered by this new technology will not be achieved.

Ragan, R. M.

1977-01-01

126

Hydrologic modeling to screen potential environmental management methods for malaria vector control in Niger  

E-print Network

This paper describes the first use of Hydrology-Entomology and Malaria Transmission Simulator (HYDREMATS), a physically based distributed hydrology model, to investigate environmental management methods for malaria vector ...

Gianotti, Rebecca Louise

127

A NEW APPROACH TO HYDROLOGIC MODELING: DERIVED DISTRIBUTIONS REVISITED. (R824780)  

EPA Science Inventory

A fractal geometric procedure to model hydrologic (geophysical) phenomena is introduced. The method consists of using derived distributions, obtained by transforming arbitrary multinomial multifractal measures via fractal interpolating functions, to represent observed hydrologic ...

128

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

E-print Network

A multicomponent coupled model of glacier hydrology 1. Theory and synthetic examples Gwenn E; published 12 November 2002. [1] Basal hydrology is acknowledged as a fundamental control on glacier dynamics of existing basal hydrology models is the treatment of the glacier bed as an isolated system. We present

Flowers, Gwenn

129

Chapman Conference on Spatial Variability in Hydrologic Modeling  

NASA Astrophysics Data System (ADS)

The AGU Chapman Conference on Spatial Variability in Hydrologic Modeling was held July 21-23, 1981, at the Colorado State University Pingree Park Campus, located in the mountains some 88.5 km (55 miles) west of Fort Collins, Colorado. The conference was attended by experimentalists and theoreticians from a wide range of disciplines, including geology, hydrology, civil engineering, watershed science, chemical engineering, geography, statistics, mathematics, meteorology, and soil science. The attendees included researchers at various levels of research experience, including a large contingent of graduate students and many senior scientists.The conference goal was to review progress and discuss research approaches to the spatial variability of catchment surface and subsurface properties in a distributed modeling context. Mathematical models of water movement dynamics within a catchment consist of linked partial differential equations that describe free surface flow and unsaturated and saturated flow in porous media. Such models are utilized extensively in attempts to understand and predict the environmental consequences of human activities such as agricultural land management, waste disposal, urbanization, etc. We are concerned with the spatial structure of the parameters in such models, the precipitation input, and the geometric complexity of the system boundaries. The emphasis of this conference was on surface and subsurface hydrological process and their interactions.

Woolhiser, D. A.; Morel-Seytoux, H. J.

130

Modeling hydrology and sediment transport in vegetative filter strips  

SciTech Connect

Sediment and sediment bounded pollutants carried by runoff from non-point sources is a major pollutant of water bodies. Vegetative filter strips (VFS) are bands of planted or indigenous vegetation used to control runoff and sediment outflow from disturbed areas. This work presents and validates a research model to study the hydrology and sediment movement in VFS. This was accomplished in four steps. The numerical solution of the overland flow kinematic wave equations is subject to numerical problems when a rapid change in parameters is encountered (kinematic shock). An improved finite element method, i.e. a Petrov-Galerkin (PG) formulation, is presented. The formulation depends on four parameters. The PG method decreased the mean sum of square error by about 65%. The finite element overland flow solution is modified and linked to the Green-Ampt infiltration equation to form a VFS-specific hydrology model. An analysis of the effect of different filter properties (soil type, slope, surface roughness, buffer length) on the major hydrological out-puts (runoff volume, velocity and peak flow rate) is made. Optimal filter performance (i.e. reduction in runoff volume, velocity and peak flow rate) is found for soils with high infiltration capacity, dense grass cover and small slopes. A sediment transport/filtration submodel (based on the University of Kentucky model) is added to the hydrology submodel. The interaction between submodels and a natural event application case to illustrate the capability of the model and its various outputs is presented in detail. An analysis of sensitivity and a field validation are performed. The most sensitive parameters are soil initial water content, vertical saturated hydraulic conductivity, particle class and grass spacing. The model predictions were compared with a set of natural events from an experimental site in the North Carolina Piedmont. In general the model performs well.

Munoz-Carpena, R.

1993-12-31

131

eWaterCycle: A high resolution global hydrological model  

NASA Astrophysics Data System (ADS)

In 2013, the eWaterCycle project was started, which has the ambitious goal to run a high resolution global hydrological model. Starting point was the PCR-GLOBWB built by Utrecht University. The software behind this model will partially be re-engineered in order to enable to run it in a High Performance Computing (HPC) environment. The aim is to have a spatial resolution of 1km x 1km. The idea is also to run the model in real-time and forecasting mode, using data assimilation. An on-demand hydraulic model will be available for detailed flow and flood forecasting in support of navigation and disaster management. The project faces a set of scientific challenges. First, to enable the model to run in a HPC environment, model runs were analyzed to examine on which parts of the program most CPU time was spent. These parts were re-coded in Open MPI to allow for parallel processing. Different parallelization strategies are thinkable. In our case, it was decided to use watershed logic as a first step to distribute the analysis. There is rather limited recent experience with HPC in hydrology and there is much to be learned and adjusted, both on the hydrological modeling side and the computer science side. For example, an interesting early observation was that hydrological models are, due to their localized parameterization, much more memory intensive than models of sister-disciplines such as meteorology and oceanography. Because it would be deadly to have to swap information between CPU and hard drive, memory management becomes crucial. A standard Ensemble Kalman Filter (enKF) would, for example, have excessive memory demands. To circumvent these problems, an alternative to the enKF was developed that produces equivalent results. This presentation shows the most recent results from the model, including a 5km x 5km simulation and a proof of concept for the new data assimilation approach. Finally, some early ideas about financial sustainability of an operational global hydrological model are presented.

van de Giesen, Nick; Bierkens, Marc; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

2014-05-01

132

The CRISPR/Cas9 System Facilitates Clearance of the Intrahepatic HBV Templates In Vivo.  

PubMed

Persistence of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) under current antiviral therapy is a major barrier to eradication of chronic hepatitis B (CHB). Curing CHB will require novel strategies for specific disruption of cccDNA. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system is a newly developed tool for site-specific cleavage of DNA targets directed by a synthetic guide RNA (gRNA) base-paired to the target DNA sequence. To examine whether this system can cleave HBV genomes, we designed eight gRNAs against HBV of genotype A. With the HBV-specific gRNAs, the CRISPR/Cas9 system significantly reduced the production of HBV core and surface proteins in Huh-7 cells transfected with an HBV-expression vector. Among eight screened gRNAs, two effective ones were identified. Interestingly, one gRNA targeting the conserved HBV sequence acted against different genotypes. Using a hydrodynamics-HBV persistence mouse model, we further demonstrated that this system could cleave the intrahepatic HBV genome-containing plasmid and facilitate its clearance in vivo, resulting in reduction of serum surface antigen levels. These data suggest that the CRISPR/Cas9 system could disrupt the HBV-expressing templates both in vitro and in vivo, indicating its potential in eradicating persistent HBV infection. PMID:25137139

Lin, Su-Ru; Yang, Hung-Chih; Kuo, Yi-Ting; Liu, Chun-Jen; Yang, Ta-Yu; Sung, Ku-Chun; Lin, You-Yu; Wang, Hurng-Yi; Wang, Chih-Chiang; Shen, Yueh-Chi; Wu, Fang-Yi; Kao, Jia-Horng; Chen, Ding-Shinn; Chen, Pei-Jer

2014-01-01

133

The CRISPR/Cas9 System Facilitates Clearance of the Intrahepatic HBV Templates In Vivo  

PubMed Central

Persistence of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) under current antiviral therapy is a major barrier to eradication of chronic hepatitis B (CHB). Curing CHB will require novel strategies for specific disruption of cccDNA. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system is a newly developed tool for site-specific cleavage of DNA targets directed by a synthetic guide RNA (gRNA) base-paired to the target DNA sequence. To examine whether this system can cleave HBV genomes, we designed eight gRNAs against HBV of genotype A. With the HBV-specific gRNAs, the CRISPR/Cas9 system significantly reduced the production of HBV core and surface proteins in Huh-7 cells transfected with an HBV-expression vector. Among eight screened gRNAs, two effective ones were identified. Interestingly, one gRNA targeting the conserved HBV sequence acted against different genotypes. Using a hydrodynamics-HBV persistence mouse model, we further demonstrated that this system could cleave the intrahepatic HBV genome-containing plasmid and facilitate its clearance in vivo, resulting in reduction of serum surface antigen levels. These data suggest that the CRISPR/Cas9 system could disrupt the HBV-expressing templates both in vitro and in vivo, indicating its potential in eradicating persistent HBV infection. PMID:25137139

Lin, Su-Ru; Yang, Hung-Chih; Kuo, Yi-Ting; Liu, Chun-Jen; Yang, Ta-Yu; Sung, Ku-Chun; Lin, You-Yu; Wang, Hurng-Yi; Wang, Chih-Chiang; Shen, Yueh-Chi; Wu, Fang-Yi; Kao, Jia-Horng; Chen, Ding-Shinn; Chen, Pei-Jer

2014-01-01

134

Nitrogen RiskAssessment Model for Scotland:II.Hydrological transport and model testing Hydrology and Earth System Sciences, 8(2), 205219 (2004) EGU  

E-print Network

Nitrogen RiskAssessment Model for Scotland:II.Hydrological transport and model testing 205 Hydrology and Earth System Sciences, 8(2), 205219 (2004) © EGU Nitrogen Risk Assessment Model for Scotland.dunn@macaulay.ac.uk Abstract The amount and concentration of N in catchment runoff is strongly controlled by a number

Boyer, Edmond

135

Simulation of flood reduction by natural river rehabilitation using a distributed hydrological model Hydrology and Earth System Sciences, 8(6), 11291140 (2004) EGU  

E-print Network

Simulation of flood reduction by natural river rehabilitation using a distributed hydrological model 1129 Hydrology and Earth System Sciences, 8(6), 11291140 (2004) © EGU Simulation of flood reduction by natural river rehabilitation using a distributed hydrological model Y.B. Liu1 , S. Gebremeskel1

Boyer, Edmond

136

Quantifying and Generalizing Hydrologic Responses to Dam Regulation using a Statistical Modeling Approach  

SciTech Connect

Despite the ubiquitous existence of dams within riverscapes, much of our knowledge about dams and their environmental effects remains context-specific. Hydrology, more than any other environmental variable, has been studied in great detail with regard to dam regulation. While much progress has been made in generalizing the hydrologic effects of regulation by large dams, many aspects of hydrology show site-specific fidelity to dam operations, small dams (including diversions), and regional hydrologic regimes. A statistical modeling framework is presented to quantify and generalize hydrologic responses to varying degrees of dam regulation. Specifically, the objectives were to 1) compare the effects of local versus cumulative dam regulation, 2) determine the importance of different regional hydrologic regimes in influencing hydrologic responses to dams, and 3) evaluate how different regulation contexts lead to error in predicting hydrologic responses to dams. Overall, model performance was poor in quantifying the magnitude of hydrologic responses, but performance was sufficient in classifying hydrologic responses as negative or positive. Responses of some hydrologic indices to dam regulation were highly dependent upon hydrologic class membership and the purpose of the dam. The opposing coefficients between local and cumulative-dam predictors suggested that hydrologic responses to cumulative dam regulation are complex, and predicting the hydrology downstream of individual dams, as opposed to multiple dams, may be more easy accomplished using statistical approaches. Results also suggested that particular contexts, including multipurpose dams, high cumulative regulation by multiple dams, diversions, close proximity to dams, and certain hydrologic classes are all sources of increased error when predicting hydrologic responses to dams. Statistical models, such as the ones presented herein, show promise in their ability to model the effects of dam regulation effects at large spatial scales as to generalize the directionality of hydrologic responses.

McManamay, Ryan A [ORNL

2014-01-01

137

Distributed Hydrologic Modeling Apps for Decision Support in the Cloud  

NASA Astrophysics Data System (ADS)

Advances in computation resources and greater availability of water resources data represent an untapped resource for addressing hydrologic uncertainties in water resources decision-making. The current practice of water authorities relies on empirical, lumped hydrologic models to estimate watershed response. These models are not capable of taking advantage of many of the spatial datasets that are now available. Physically-based, distributed hydrologic models are capable of using these data resources and providing better predictions through stochastic analysis. However, there exists a digital divide that discourages many science-minded decision makers from using distributed models. This divide can be spanned using a combination of existing web technologies. The purpose of this presentation is to present a cloud-based environment that will offer hydrologic modeling tools or 'apps' for decision support and the web technologies that have been selected to aid in its implementation. Compared to the more commonly used lumped-parameter models, distributed models, while being more intuitive, are still data intensive, computationally expensive, and difficult to modify for scenario exploration. However, web technologies such as web GIS, web services, and cloud computing have made the data more accessible, provided an inexpensive means of high-performance computing, and created an environment for developing user-friendly apps for distributed modeling. Since many water authorities are primarily interested in the scenario exploration exercises with hydrologic models, we are creating a toolkit that facilitates the development of a series of apps for manipulating existing distributed models. There are a number of hurdles that cloud-based hydrologic modeling developers face. One of these is how to work with the geospatial data inherent with this class of models in a web environment. Supporting geospatial data in a website is beyond the capabilities of standard web frameworks and it requires the use of additional software. In particular, there are at least three elements that are needed: a geospatially enabled database, a map server, and geoprocessing toolbox. We recommend a software stack for geospatial web application development comprising: MapServer, PostGIS, and 52 North with Python as the scripting language to tie them together. Another hurdle that must be cleared is managing the cloud-computing load. We are using HTCondor as a solution to this end. Finally, we are creating a scripting environment wherein developers will be able to create apps that use existing hydrologic models in our system with minimal effort. This capability will be accomplished by creating a plugin for a Python content management system called CKAN. We are currently developing cyberinfrastructure that utilizes this stack and greatly lowers the investment required to deploy cloud-based modeling apps. This material is based upon work supported by the National Science Foundation under Grant No. 1135482

Swain, N. R.; Latu, K.; Christiensen, S.; Jones, N.; Nelson, J.

2013-12-01

138

Development of a "Hydrologic Equivalent Wetland" Concept for Modeling Cumulative Effects of Wetlands on Watershed Hydrology  

NASA Astrophysics Data System (ADS)

Wetlands are one of the most important watershed microtopographic features that affect, in combination rather than individually, hydrologic processes (e.g., routing) and the fate and transport of constituents (e.g., sediment and nutrients). Efforts to conserve existing wetlands and/or to restore lost wetlands require that watershed-level effects of wetlands on water quantity and water quality be quantified. Because monitoring approaches are usually cost or logistics prohibitive at watershed scale, distributed watershed models, such as the Soil and Water Assessment Tool (SWAT), can be a best resort if wetlands can be appropriately represented in the models. However, the exact method that should be used to incorporate wetlands into hydrologic models is the subject of much disagreement in the literature. In addition, there is a serious lack of information about how to model wetland conservation-restoration effects using such kind of integrated modeling approach. The objectives of this study were to: 1) develop a "hydrologic equivalent wetland" (HEW) concept; and 2) demonstrate how to use the HEW concept in SWAT to assess effects of wetland restoration within the Broughton's Creek watershed located in southwestern Manitoba of Canada, and of wetland conservation within the upper portion of the Otter Tail River watershed located in northwestern Minnesota of the United States. The HEWs were defined in terms of six calibrated parameters: the fraction of the subbasin area that drains into wetlands (WET_FR), the volume of water stored in the wetlands when filled to their normal water level (WET_NVOL), the volume of water stored in the wetlands when filled to their maximum water level (WET_MXVOL), the longest tributary channel length in the subbasin (CH_L1), Manning's n value for the tributary channels (CH_N1), and Manning's n value for the main channel (CH_N2). The results indicated that the HEW concept allows the nonlinear functional relations between watershed processes and wetland characteristics (e.g., size and morphology) to be accurately represented in the models. The loss of the first 10 to 20% of the wetlands in the Minnesota study area would drastically increase the peak discharge and loadings of sediment, total phosphorus (TP), and total nitrogen (TN). On the other hand, the justifiable reductions of the peak discharge and loadings of sediment, TP, and TN in the Manitoba study area may require that 50 to 80% of the lost wetlands be restored. Further, the comparison between the predicted restoration and conservation effects revealed that wetland conservation seems to deserve a higher priority while both wetland conservation and restoration may be equally important. Moreover, although SWAT was used in this study, the HEW concept is generic and can also be applied with any other hydrologic models.

Wang, X.; Liu, T.; Li, R.; Yang, X.; Duan, L.; Luo, Y.

2012-12-01

139

A Coupled Surface/Subsurface Model for Hydrological Drought Investigations  

NASA Astrophysics Data System (ADS)

Hydrological droughts occur when storage in the ground and surface-water bodies falls below statistical average. Due to the inclusion of regional groundwater, hydrological droughts evolve relatively slowly. The atmospheric and surface components of the hydrological cycle have been widely studied, are well understood, and their prognoses are fairly accurate. In large-scale land surface models on the other hand, subsurface (groundwater) flow processes are usually assumed unidirectional and limited to the vertically-downward percolation and the horizontal runoffs. The vertical feedback from groundwater to the unsaturated zone as well as the groundwater recharge from surface waters are usually misrepresented, resulting in poor model performance during low-flow periods. The feedback is important during meteorological droughts because it replenishes soil moisture from ground- and surface water, thereby delaying the onset of agricultural droughts. If sustained for long periods however, the depletion can significantly reduce surface and subsurface storage and lead to severe hydrological droughts. We hypothesise that an explicit incorporation of the groundwater component into an existing land surface model would lead to better representation of low flows, which is critical for drought analyses. It would also improve the model performance during low-flow periods. For this purpose, we coupled the process-based mHM surface model (Samaniego et al. 2010) with MODFLOW (Harbaugh 2005) to analyse droughts in the Unstrut catchment, one of the tributaries of the Elbe. The catchment is located in one of the most drought-prone areas of Germany. We present results for stand-alone and coupled mHM simulations for the period 1970-2000. References Arlen W. Harbaugh. MODFLOW-2005, The U.S. Geological Survey Modular Ground-water Model-the Ground-water Flow Process, chapter Modelling techniques, sec. A. Ground water, pages 1:1-9:62. USGS, 2005. Luis Samaniego, Rohini Kumar, and Sabine Attinger. Multiscale parameter regionalization of a grid-based hydrologic model at the mesoscale. Water Resour. Res., 46(W05523), 2010. doi: 10.1029/2008WR007327.

Musuuza, J. L.; Kumar, R.; Samaniego, L. E.; Fischer, T.; Kolditz, O.; Attinger, S.

2013-12-01

140

Understanding hydrologic partitioning: Combining mechanistic modelling with signature analysis to understand controls on hydrologic behaviour in headwater catchments  

NASA Astrophysics Data System (ADS)

Headwater streams are the most abundant portion of the river network but the least monitored. As such, we have a limited understanding of headwater stream behaviors and how they are influenced by watershed properties such as topography, geology, and vegetation. Given the lack of runoff monitoring within headwater streams, improving an understanding of how catchment properties influence hydrologic behavior is necessary for transferring information from instrumented areas to ungauged sites. We utilize this concept to understand physical controls on similarities and differences in hydrologic behavior for five adjacent sub-catchments located in the Tenderfoot Creek Experimental Forest in central Montana with variable topographies and vegetative cover. We use an uncalibrated, distributed, physically-based watershed model, the Distributed Hydrology-Soil-Vegetation Model (DHSVM) combined with global, variance-based sensitivity analysis to investigate physical controls on a range of model-predicted hydrologic behavior (i.e. states) across multiple time scales. We implement comparative hydrology to improve our understanding of headwater watershed runoff behavior within this framework by directly relating physical properties of a given catchment to process-based predictions of hydrologic behavior, i.e. signatures. We find that across different hydrologic fluxes, including streamflow, evapotranspiration, and snow water equivalent change, only a few vegetation and soil parameters control the variability in hydrologic behavior for all sub-catchments. These controls are similar at the annual and weekly scale, though parameter influence varies seasonally from wet to dry periods. Three of the five watersheds exhibited different controls on hydrologic behavior, likely resulting from past vegetation treatments and differing surficial geology within these sub-watersheds. This framework has strong potential to inform how similarities and differences in headwater watershed characteristics can influence the variability in spatially and temporally varying hydrologic signatures. We ultimately demonstrate that the influences of soil and vegetation across headwater watersheds vary, using a modeling framework to understand physical controls on hydrologic signatures at a high resolution. We suggest that this approach can especially enhance estimation of controls on headwater watershed behavior at unmonitored sites.

Wagener, Thorsten; Kelleher, Christa; Pianosi, Francesca; McGlynn, Brian

2014-05-01

141

Hydrologic modeling of soil water storage in landfill cover systems  

SciTech Connect

The accuracy of modeling soil water storage by two hydrologic models, CREAMS and HELP, was tested by comparing simulation results with field measurements of soil moisture in eight experimental landfill cover systems having a range of well-defined soil profiles and vegetative covers. Regression analysis showed that CREAMS generally represented soil moisture more accurately than HELP simulations. Soil profiles that more closely resembled natural agricultural soils were more accurately modeled than highly artificial layered soil profiles. Precautions for determining parameter values for model input and for interpreting simulation results are discussed.

Barnes, F.J.; Rodgers, J.C.

1987-01-01

142

The hydrology of malaria : field observations and mechanistic modeling of the malaria transmission response to environmental climatic variability  

E-print Network

A coupled HYDrology, Entomology and MAlaria Transmission Simulator (HYDREMATS) has been developed. The model simulates the hydrological and climatological determinants of malaria transmission mechanistically and at high ...

Bomblies, Arne

2009-01-01

143

Hydrologic effects of evapotranspiration representation in a Richards equation based distributed hydrologic model at the catchment scale  

NASA Astrophysics Data System (ADS)

Evapotranspiration (ET) is a key water budget term that is rarely evaluated in hydrologic modeling due to the scarcity of observed actual ET fluxes. However, the ET process representation within a hydrologic model is important as it affects the simulated hydrologic response. Here we illustrate how different ET representations affect both the hydrograph and the soil moisture states within MODHMS, a Richards' equation based distributed hydrologic model at the catchment scale. MODHMS, a MODFLOW based model, has a flexible modular structure that allowed testing of 4 different base case ET scenarios: two MODFLOW ET representations (linear and piece-wise linear) and one physically based ET model in two configurations. These 4 ET sub-models were applied sequentially for the case of the well-studied 10.5 ha - Tarrawarra catchment in Australia keeping the soil parameterization constant. The hydrologic response sensitivity to each of the ET sub-models parameterization was evaluated. The ET process representation chosen for use in MODHMS is important for adequately representing soil saturation areas, lateral flow and drying of the upslope areas of the catchment as well as the outflow hydrograph.

Cristea, N. C.; Burges, S. J.

2013-12-01

144

Calibration and validation of DRAINMOD to model bioretention hydrology  

NASA Astrophysics Data System (ADS)

SummaryPrevious field studies have shown that the hydrologic performance of bioretention cells varies greatly because of factors such as underlying soil type, physiographic region, drainage configuration, surface storage volume, drainage area to bioretention surface area ratio, and media depth. To more accurately describe bioretention hydrologic response, a long-term hydrologic model that generates a water balance is needed. Some current bioretention models lack the ability to perform long-term simulations and others have never been calibrated from field monitored bioretention cells with underdrains. All peer-reviewed models lack the ability to simultaneously perform both of the following functions: (1) model an internal water storage (IWS) zone drainage configuration and (2) account for soil-water content using the soil-water characteristic curve. DRAINMOD, a widely-accepted agricultural drainage model, was used to simulate the hydrologic response of runoff entering a bioretention cell. The concepts of water movement in bioretention cells are very similar to those of agricultural fields with drainage pipes, so many bioretention design specifications corresponded directly to DRAINMOD inputs. Detailed hydrologic measurements were collected from two bioretention field sites in Nashville and Rocky Mount, North Carolina, to calibrate and test the model. Each field site had two sets of bioretention cells with varying media depths, media types, drainage configurations, underlying soil types, and surface storage volumes. After 12 months, one of these characteristics was altered - surface storage volume at Nashville and IWS zone depth at Rocky Mount. At Nashville, during the second year (post-repair period), the Nash-Sutcliffe coefficients for drainage and exfiltration/evapotranspiration (ET) both exceeded 0.8 during the calibration and validation periods. During the first year (pre-repair period), the Nash-Sutcliffe coefficients for drainage, overflow, and exfiltration/ET ranged from 0.6 to 0.9 during both the calibration and validation periods. The bioretention cells at Rocky Mount included an IWS zone. For both the calibration and validation periods, the modeled volume of exfiltration/ET was within 1% and 5% of the estimated volume for the cells with sand (Sand cell) and sandy clay loam (SCL cell) underlying soils, respectively. Nash-Sutcliffe coefficients for the SCL cell during both the calibration and validation periods were 0.92.

Brown, R. A.; Skaggs, R. W.; Hunt, W. F.

2013-04-01

145

Distributed Hydrologic Modeling of LID in The Woodlands, Texas  

NASA Astrophysics Data System (ADS)

As early as the 1960s, the Woodlands, TX employed stormwater management similar to modern Low Impact Development (LID) design. Innovative for its time, the master drainage plan attempted to minimize adverse impact to the 100-year floodplain and reduce the impact of development on the natural environment. Today, it is Texas's most celebrated master-planned community. This paper employs the use of NEXRAD radar rainfall in the distributed hydrologic model, VfloTM, to evaluate the effectiveness of The Woodlands master drainage design as a stormwater management technique. Three models were created in order to analyze the rainfall-runoff response of The Woodlands watershed under different development conditions: two calibrated, fully distributed hydrologic models to represent the (A) undeveloped and (B) 2006-development conditions and (C) a hypothetical, highly urbanized model, representing Houston-style development. Parameters, such as imperviousness and land cover, were varied in order to represent the different developed conditions. The A and B models were calibrated using NEXRAD radar rainfall for two recent storm events in 2008 and 2009. All three models were used to compare peak flows, discharge volumes and time to peak of hydrographs for the recent radar rainfall events and a historical gaged rainfall event that occurred in 1974. Results show that compared to pre-developed conditions, the construction of The Woodlands resulted in an average increase in peak flows of only 15% during small storms and 27% during a major event. Furthermore, when compared to the highly urbanized model, peak flows are often two to three times smaller for the 2006-model. In the 2006-model, the peak flow of the 100 year event was successfully attenuated, suggesting that the design of The Woodlands effectively protects the development from the 1% occurrence storm event using LID practices and reservoirs. This study uses a calibrated hydrologic distributed-model supported by NEXRAD radar rainfall to show that innovative LID strategies have been an effective stormwater management technique in The Woodlands, TX.

Bedient, P.; Doubleday, G.; Sebastian, A.; Fang, N.

2012-12-01

146

HBV life cycle is restricted in mouse hepatocytes expressing human NTCP  

PubMed Central

Recent studies have revealed that human sodium taurocholate cotransporting polypeptide (SLC10A1 or NTCP) is a functional cellular receptor for hepatitis B virus (HBV). However, whether human NTCP can support HBV infection in mouse hepatocyte cell lines has not been clarified. Because an HBV-permissible mouse model would be helpful for the study of HBV pathogenesis, it is necessary to investigate whether human NTCP supports the susceptibility of mouse hepatocyte cell lines to HBV. The results show that exogenous human NTCP expression can render non-susceptible HepG2 (human), Huh7 (human), Hepa1–6 (mouse), AML-12 (mouse) cell lines and primary mouse hepatocyte (PMH) cells susceptible to hepatitis D virus (HDV) which employs HBV envelope proteins. However, human NTCP could only introduce HBV susceptibility in human-derived HepG2 and Huh7 cells, but not in mouse-derived Hepa1–6, AML-12 or PMH cells. These data suggest that although human NTCP is a functional receptor that mediates HBV infection in human cells, it cannot support HBV infection in mouse hepatocytes. Our study indicated that the restriction of HBV in mouse hepatocytes likely occurs after viral entry but prior to viral transcription. We have excluded the role of mouse hepatocyte nuclear factors in the restriction of the HBV life cycle and showed that knockdown or inhibition of Sting, TBK1, IRF3 or IRF7, the components of the anti-viral signaling pathways, had no effect on HBV infection in mouse hepatocytes. Therefore, murine restriction factors that limit HBV infection need to be identified before a HBV-permissible mouse line can be created. PMID:24509445

Li, Hanjie; Zhuang, Qiuyu; Wang, Yuze; Zhang, Tianying; Zhao, Jinghua; Zhang, Yali; Zhang, Junfang; Lin, Yi; Yuan, Quan; Xia, Ningshao; Han, Jiahuai

2014-01-01

147

FLEXIBLE PROCESS-BASED HYDROLOGICAL MODELLING FRAMEWORK FOR FLOOD FORECASTING – MIKE SHE  

Microsoft Academic Search

Abstract New developments ,of grid-based hydrological modelling ,have been spurred by increasing access to meteorological modelling, radar and satellite remote sensing. However, state of the art operational hydrological forecasting models ,are usually sub-catchment-based conceptual orempirical models, using to a greater or lesser degree the physics of rainfall-runoff processes. By contrast, state-of-the-art hydrological modelling is represented by fully distributed physically-based modelling

W. Szalinska

148

Developing a TeraGrid Based Land Surface Hydrology and Weather Modeling Interface  

E-print Network

Developing a TeraGrid Based Land Surface Hydrology and Weather Modeling Interface Hsin-I Chang1 iclimate@purdue.edu -------------------- -------------------- 1 INTRODUCTION Real world hydrologic cyberinfrastructure (CI) has been articulated in many workshops and meetings of the environmental and hydrologic

Jiang, Wen

149

Journal of Hydrology 161 (1994)91-108 Variably saturated modeling of transient drainage: sensitivity  

E-print Network

Journal of Hydrology ELSEVIER [1] Journal of Hydrology 161 (1994)91-108 Variably saturated modeling-1694(94)02509-A #12;92 W.R. Wise et al. / Journal of Hydrology 161 (1994) 91-108 transient unconfined flow through

Clement, Prabhakar

150

Graduate Opportunities in Earth Systems Modeling and Climate Impacts on Hydrology and Water Resources  

E-print Network

Graduate Opportunities in Earth Systems Modeling and Climate Impacts on Hydrology and Water on hydrology and water resources. Our research focuses on studying the relationship between large scale hydrological processes and climate change in managed and natural ecosystems, water and energy fluxes, land

151

Intercomparison of hydrologic processes in global climate models  

NASA Technical Reports Server (NTRS)

In this report, we address the intercomparison of precipitation (P), evaporation (E), and surface hydrologic forcing (P-E) for 23 Atmospheric Model Intercomparison Project (AMIP) general circulation models (GCM's) including relevant observations, over a variety of spatial and temporal scales. The intercomparison includes global and hemispheric means, latitudinal profiles, selected area means for the tropics and extratropics, ocean and land, respectively. In addition, we have computed anomaly pattern correlations among models and observations for different seasons, harmonic analysis for annual and semiannual cycles, and rain-rate frequency distribution. We also compare the joint influence of temperature and precipitation on local climate using the Koeppen climate classification scheme.

Lau, W. K.-M.; Sud, Y. C.; Kim, J.-H.

1995-01-01

152

Parallelization of a hydrological model using the message passing interface  

USGS Publications Warehouse

With the increasing knowledge about the natural processes, hydrological models such as the Soil and Water Assessment Tool (SWAT) are becoming larger and more complex with increasing computation time. Additionally, other procedures such as model calibration, which may require thousands of model iterations, can increase running time and thus further reduce rapid modeling and analysis. Using the widely-applied SWAT as an example, this study demonstrates how to parallelize a serial hydrological model in a Windows® environment using a parallel programing technology—Message Passing Interface (MPI). With a case study, we derived the optimal values for the two parameters (the number of processes and the corresponding percentage of work to be distributed to the master process) of the parallel SWAT (P-SWAT) on an ordinary personal computer and a work station. Our study indicates that model execution time can be reduced by 42%–70% (or a speedup of 1.74–3.36) using multiple processes (two to five) with a proper task-distribution scheme (between the master and slave processes). Although the computation time cost becomes lower with an increasing number of processes (from two to five), this enhancement becomes less due to the accompanied increase in demand for message passing procedures between the master and all slave processes. Our case study demonstrates that the P-SWAT with a five-process run may reach the maximum speedup, and the performance can be quite stable (fairly independent of a project size). Overall, the P-SWAT can help reduce the computation time substantially for an individual model run, manual and automatic calibration procedures, and optimization of best management practices. In particular, the parallelization method we used and the scheme for deriving the optimal parameters in this study can be valuable and easily applied to other hydrological or environmental models.

Wu, Yiping; Li, Tiejian; Sun, Liqun; Chen, Ji

2013-01-01

153

Self-Organizing Basal Hydrology for Ice Sheet Flowline Models  

NASA Astrophysics Data System (ADS)

Subglacial water pressure is a fundamental control on basal drag and glacier sliding rates. However, it has seldom been included as a variable in glacier flow models, mainly due to the great difficulty in calculating water pressure in a realistic yet tractable way. Here we present preliminary results of a simple basal hydrological model designed for coupling to ice sheet flow models. A key feature of the model is that hydraulic conductivity k evolves in response to water discharge Q (which melts ice and increases the capacity of the system) and effective pressure pi - pw (reducing system capacity through ice creep). The timescales of these processes relative to temporal variations in surface water inputs produces contrasting pressure-discharge relationships as an emergent property of the model. Specifically, pw varies directly with Q over diurnal timescales, whereas pw is inversely proportional to Q on seasonal timescales. In combination with suitable friction laws, the hydrology model provides an adaptive basal boundary condition for flowline models. Despite its simplicity, the model allows a rich variety of behaviour to be simulated, including spring 'speed-up' events and summer 'slowdowns'.

Rutt, I. C.; Benn, D.; Cook, S.; Hulton, N. R.

2013-12-01

154

Characterising the hydrological response to climate change of a remote tropical mountainous catchment: a multi-model approach  

NASA Astrophysics Data System (ADS)

Process-based conceptual rainfall-runoff models are useful to understand runoff generation at different time and spatial resolutions. Contrary to physically-based models, they do not rely much on field observations (e.g. soil physical properties) which may not be available everywhere. Instead, these mathematical tools close the water balance and predict runoff as a function of some empirical parameters. Since corresponding values are hardly measurable, modellers usually proceed to a calibration against available observations to obtain an acceptable match between observations and predictions. However, in the case of poorly monitored areas such as elevated catchments in the Andean Cordillera, good high frequency calibration data available over a long time span are scarce. Therefore, in spite of the development of multiple effective automatized calibration techniques in recent years, results remain uncertain because of the non-uniqueness of optimal parameter sets. A state-of-the-art option to cope with this predictive uncertainty is to consider ensembles of predictions rather than single ones. Furthermore, by gathering more independent parameterisations of the same processes, multi-model approaches allow a better representation of the uncertainty than multiple realisations of the same, eventually biased, model structure subjectively chosen by the modeller based on previous experience or project requirements. As a demonstration of the usefulness of this approach in scarcely-monitored areas, we present here results of an ensemble of heterogeneous rainfall-runoff models applied to the remote San Francisco (75 km2) tropical montane forest catchment, located in the southern part of Ecuador. Each of the 7 models (CHIMP, HBV-D, HBV-light, HMS, LASCAM, NAM, SWAT) is applied to simulate runoff whilst being forced by 6 increasingly uncertain meteorological data: on-site precipitation gauges record (also used for calibration), bias-corrected downscaled re-analysis (SDSM) output of the CCSM Regional Climate Model (RCM) over the first decade of the 21st century, and output of the same RCM forced by two different IPCC emission scenarios (A1B, B1) for two decades of the middle (2050-2059) and the end of the current century (2090-2099). Results show that the annual cumulative runoff and maximum flows should increase in this area during the 21st century. Furthermore, in spite of a good agreement in the timing of seasonal runoff patterns between rainfall-runoff models forced by the same input data, there is a great variability in the magnitude of predicted extreme values. The uncertainty in the RCM emission scenarios is not greater than the uncertainty between hydrological model predictions but the ensemble still allows targeting the most probable future.

Exbrayat, J.-F.; Timbe, E.; Plesca, I.; Kraft, P.; Windhorst, D.; Trachte, K.; Buytaert, W.; Breuer, L.

2012-04-01

155

An analogue model for subglacial hydrology (Invited)  

NASA Astrophysics Data System (ADS)

Analogue models have been used extensively in the Earth sciences to improve understanding of natural processes. Here we apply these techniques to simulate water flow under ice sheets and glaciers. Ice deformation is represented with polydimethyl-siloxane (PDMS) - a liquid polymer used extensively in the tectonics-related deformation experiments. PDMS is a transparent, non-toxic material with a specific weight similar to that of ice and a strain-rate dependent viscosity making it well-suited to ice flow studies. The polymer is loaded into a 4’x 6’ plastic box coated with a water-based lubricant across 80% of the box width to reduce friction at the interface between the polymer and the base of the box. Water is injected at this interface via a set of tubes that distribute the incoming water supply across the upstream end at a constant discharge. We measure horizontal surface displacement by tracking several bright stickers placed on the surface of the polymer through a sequence of images that make up each experimental run. Coincident water discharge and channel pattern measurements are made to correlate changes in discharge to changes in channel geometry and surface motion. Of particular interest is the response of the channel system to discharge pulses. To observe this we change discharge into the flume from ~70 cm3/s to 550 cm3/s which reflects an ~8-fold increase in discharge and represents a typical diurnal discharge fluctuation observed on alpine glaciers.

Catania, G. A.; Buttles, J. L.; Mohrig, D. C.

2009-12-01

156

The Anti-hepatitis B Virus Activity of Boehmeria nivea Extract in HBV-viremia SCID Mice.  

PubMed

Boehmeria nivea extract (BNE) is widely used in southern Taiwan as a folk medicine for hepato-protection and hepatitis treatment. In previous studies, we demonstrated that BNE could reduce the supernatant hepatitis B virus (HBV) DNA in HBV-producing HepG2 2.2.15 cells. In the present study, we established an animal model of HBV viremia and used it to validate the efficacy of BNE in vivo. In this animal model, serum HBV DNA and HBsAg were elevated in accordance with tumor growth. To evaluate the anti-HBV activity of BNE, HBV-viremia mice were built up after one subcutaneous inoculation of HepG2 2.2.15 tumor cells in severe combined immunodeficiency mice over 13 days. The levels of serum HBV DNA were elevated around 10(5)-10(6) copies per milliliter. Both oral and intraperitoneal administration of BNE were effective at inhibiting the production of HBsAg and HBV DNA, whereas tumor growth was not affected by all test articles. Intraperitoneal administration of BNE appeared to have greater potential to inhibit serum HBV DNA levels compared with oral administration under the same dosage. Notably, reduced natural killer cell activity was also observed after high dosage of BNE administration, and this correlated with reduced serum HBV DNA. In conclusion, BNE exhibited potential anti-HBV activity in an animal model of HBV viremia. PMID:18955304

Chang, Jia-Ming; Huang, Kai-Ling; Yuan, Thomas Ta-Tung; Lai, Yiu-Kay; Hung, Le-Mei

2010-06-01

157

Parameter Sensitivity analysis for hydrological model improvement in diverse catchments  

NASA Astrophysics Data System (ADS)

We investigate the sensitivity of the semi-distributed TopNet hydrological model, in order to understand the important hydrologic processes and influential model parameters to be accurately calibrated. Using different objective functions to evaluate the model performance, sensitivity analysis was done for TopNet applications in seven catchments located in South and North Island of New Zealand, with diverse watershed characteristics (i.e., topographic properties, response behaviours and geological features). The sensitivity approach combining the global sensitivity analysis methodology, Morris method and State Dependent Parameter (SDP) method was used in this study. Generally, the most sensitive parameters are precipitation multiplier( to correct water balance), TOPMODEL f parameter and soil water capacity which contributes to over 50% model uncertainty, while other parameters (e.g., snowmelt and routing parameters) are watershed and objective function dependent. It has being found that shape of the catchments and objective function have a strong influence on the sensitivity of the parameters. A relationship between the catchment feature and the sensitivity of the parameters was established. This will help in selection of sensitive parameters for catchments of interest. Which will help in proper calibration of the model parameters. That in turn will help in improving the model structure and reducing the uncertainty in the prediction due to parameterisation.

Singh, Shailesh Kumar; Yang, Jing; McMillan, Hilary

2014-05-01

158

Genetic Algorithm Optimization of Artificial Neural Networks for Hydrological Modelling  

NASA Astrophysics Data System (ADS)

This paper will consider the case for genetic algorithm optimization in the development of an artificial neural network model. It will provide a methodological evaluation of reported investigations with respect to hydrological forecasting and prediction. The intention in such operations is to develop a superior modelling solution that will be: \\begin{itemize} more accurate in terms of output precision and model estimation skill; more tractable in terms of personal requirements and end-user control; and/or more robust in terms of conceptual and mechanical power with respect to adverse conditions. The genetic algorithm optimization toolbox could be used to perform a number of specific roles or purposes and it is the harmonious and supportive relationship between neural networks and genetic algorithms that will be highlighted and assessed. There are several neural network mechanisms and procedures that could be enhanced and potential benefits are possible at different stages in the design and construction of an operational hydrological model e.g. division of inputs; identification of structure; initialization of connection weights; calibration of connection weights; breeding operations between successful models; and output fusion associated with the development of ensemble solutions. Each set of opportunities will be discussed and evaluated. Two strategic questions will also be considered: [i] should optimization be conducted as a set of small individual procedures or as one large holistic operation; [ii] what specific function or set of weighted vectors should be optimized in a complex software product e.g. timings, volumes, or quintessential hydrological attributes related to the 'problem situation' - that might require the development flood forecasting, drought estimation, or record infilling applications. The paper will conclude with a consideration of hydrological forecasting solutions developed on the combined methodologies of co-operative co-evolution and operational specialization. The standard approach to neural-evolution is at the network level such that a population of working solutions is manipulated until the fittest member is found. SANE [Symbiotic Adaptive Neuro-Evolution]1 source code offers an alternative method based on co-operative co-evolution in which a population of hidden neurons is evolved. The task of each hidden neuron is to establish appropriate connections that will provide: [i] a functional solution and [ii] performance improvements. Each member of the population attempts to optimize one particular aspect of the overall modelling process and evolution can lead to several different forms of specialization. This method of adaptive evolution also facilitates the creation of symbiotic relationships in which individual members must co-operate with others - who must be present - to permit survival. 1http://www.cs.utexas.edu/users/nn/pages/software/abstracts.html#sane-c

Abrahart, R. J.

2004-05-01

159

A flexible modeling package for topographically based watershed hydrology  

NASA Astrophysics Data System (ADS)

An OBJect-oriented TOPographic-based (OBJTOP) hydrological model with a graphical user interface (GUI) was created using object-oriented design (OOD) methods and the objected-oriented programming (OOP) language-C++. OBJTOP presents an array of alternative TOPMODEL hydrological processes of (1) saturation excess or the mixture of infiltration/saturation excess overland flow, (2) exponential or power law decay of hydraulic conductivity with soil depth, (3) topographic index (TI) or soil topographic index (STI) weighting of run-off likelihood, and (4) simulations with or without channel routing, to explain watershed response and increase flexibility and applicability. OBJTOP utilized an object-oriented design (OOD) approach, including the 'inheritance' concept to study individual objects (or processes) at multiple levels, and the 'aggregation' concept to study the interactions of objects (or processes). Further, OOD readily provides for model extension, creating a description of hydrologic processes in a natural, direct, concise, and adaptable manner distinct from procedurally designed and implemented models. The OBJTOP GUI provides an efficient tool for data input, parameter modification, simulation scheme selection and model calibration with three objective functions, including Nash-Sutcliffe. Graphical outputs include time series plots of precipitation depth, partitioned run-off volumes, watertable depth (average or TI/STI based), and map graphics of TI, STI, and depth to watertable. Applications illustrating OBJTOP ability and flexibility include simulation of the TOPMODEL standard Slapton Wood, UK dataset, and simulation of Ward Pound Ridge, NY a small forested catchment with power function decay of hydraulic conductivity and extensive impervious surfaces.

Wang, Jun; Endreny, Theodore A.; Hassett, James M.

2005-11-01

160

Input Variable Selection for Hydrologic Modeling Using Anns  

NASA Astrophysics Data System (ADS)

The use of artificial neural network (ANN) models in water resources applications has grown considerably over the last couple of decades. In learning problems, where a connectionist network is trained with a finite sized training set, better generalization performance is often obtained when unneeded weights in the network are eliminated. One source of unneeded weights comes from the inclusion of input variables that provide little information about the output variables. Hence, in the ANN modeling methodology, one of the approaches that has received little attention, is the selection of appropriate model inputs. In the past, different methods have been used for identifying and eliminating these input variables. Normally, linear methods of Auto Correlation Function (ACF) and Partial Auto Correlation Function (PACF) have been adopted. For nonlinear physical systems e.g. hydrological systems, model inputs selected based on the linear correlation analysis among input and output variables cannot assure to capture the non-linearity in the system. In the present study, two of the non-linear methods have been explored for the Input Variable Selection (IVS). The linear method employing ACF and PACF is also used for comparison purposes. The first non-linear method utilizes a measure of the Mutual Information Criterion (MIC) to characterize the dependence between a potential model input and the output, which is a step wise input selection procedure. The second non-linear method is improvement over the first method which eliminates redundant inputs based on a partial measure of mutual information criterion (PMIC), which is also a step wise procedure. Further, the number of input variables to be considered for the development of ANN model was determined using the Principal Component Analysis (PCA), which previously used to be done by trial and error approach. The daily river flow data derived from Godavari River Basin @ Polavaram, Andhra Pradesh, India, and the daily average rainfall data of three rain gauge stations spatially distributed in Godavari River Basin have been employed to evaluate all the IVS methods for ANN hydrologic model development. Single hidden layer architecture trained using Levenberg-Marquardt algorithm (LMA) has been employed. A wide range of error statistics was used to evaluate the performance of all the models developed with different input selection methods in this study. It has been found that PCA helps to fix the number of input variables to be considered for the model development. The results obtained show that the ANN hydrologic model developed using the inputs based on the first non-linear method performed better than the model developed using the inputs based on the linear method. Further, the ANN hydrologic model developed using the inputs based on the second non-linear method performed the best among all the models developed on various IVS methods investigated in this study. It is recommended that PCA should first be used to determine the number of inputs to be selected and then the second non-linear method should be used to select the specific inputs for the development of ANN hydrologic model.

Ganti, R.; Jain, A.

2011-12-01

161

Remote sensing inputs to landscape models which predict future spatial land use patterns for hydrologic models  

NASA Technical Reports Server (NTRS)

A tropical forest area of Northern Thailand provided a test case of the application of the approach in more natural surroundings. Remote sensing imagery subjected to proper computer analysis has been shown to be a very useful means of collecting spatial data for the science of hydrology. Remote sensing products provide direct input to hydrologic models and practical data bases for planning large and small-scale hydrologic developments. Combining the available remote sensing imagery together with available map information in the landscape model provides a basis for substantial improvements in these applications.

Miller, L. D.; Tom, C.; Nualchawee, K.

1977-01-01

162

Hydrologic Modeling of a Bioinfiltration Best Management Practice  

NASA Astrophysics Data System (ADS)

The goal of this research was to develop a methodology for modeling a bioinfiltration best management practice (BMP) built in a dormitory area on the campus of Villanova University in Pennsylvania. The objectives were to quantify the behavior of the BMP through the different seasons and rainfall events; better understand the physical processes governing the system's behavior; and develop design criteria. The BMP was constructed in 2001 by excavating within an existing traffic island, backfilling with a sand/soil mixture, and planting with salt tolerant grasses and shrubs native to the Atlantic shore. It receives runoff from the asphalt (0.26 hectare) and turf (0.27 hectare) surfaces of the watershed. Monitoring supported by the hydrologic model shows that the facility infiltrates a significant fraction of the annual precipitation, substantially reducing the delivery of nonpoint source pollution and erosive surges downstream. A hydrologic model was developed using HECHMS to represent the site and the BMP using Green-Ampt and kinematic wave methods. Instruments allow comparison of the modeled and measured water budget parameters. The model, incorporating seasonally variable parameters, predicts the volumes infiltrated and bypassed by the BMP, confirming the applicability of the selected methods for the analysis of bioinfiltration BMPs.

Heasom, William; Traver, Robert G.; Welker, Andrea

2006-10-01

163

Assessing spatial patterns to characterize performance in hydrological modeling  

NASA Astrophysics Data System (ADS)

In Hydrology, spatially distributed models are traditionally evaluated against a single spatially aggregated catchment scale observation in form of river discharge with the conviction that it features the correct simulation of catchment-inherent distributed variables. Recent advances in fully distributed grid based model codes, the availability of spatially distributed data (remote sensing and intensive field studies) and computational power allow a shift towards a spatial model evaluation away from the traditional aggregated evaluation. The need of this paradigm shift is demanded in literature; however no single spatial performance metric was identified yet that proofed suitable for comparing observed and simulated spatial patterns. The goal of this study is to develop and test simple and flexible metrics for assessing spatial patterns of distributed hydrological variables that go beyond global statistics. These metrics, individually or collectively can later be used as performance criteria in the calibration process of hydrological models. Observed and simulated land surface temperature, by the MODIS satellite and by MIKE SHE, a coupled and fully distributed hydrological model, respectively are used as a benchmark to test promising spatial metrics. Additionally a synthetic dataset which contains systematic temperature perturbations, e.g. a general bias or a shift/displacement of data, is generated to test strengths and weaknesses of the spatial metrics. Four quantitative methodologies for comparing spatial patterns are brought forward in this study: (1) A fuzzy set approach that incorporates both fuzziness of location and fuzziness of category. (2) Kappa statistic that expresses the similarity between two maps based on a contingency table (error matrix). (3) An extended version of (2) by considering both fuzziness in location and fuzziness in category. (4) Increasing the information content of a single cell by aggregating neighborhood cells at different window sizes; then computing mean and standard deviation. All algorithms except (2) require subjective judgment: E.g. a distance decay function is utilized to compute the similarity values of neighborhood cells for the fuzziness of location. Therefore a web-based survey is set up where participants are asked to grade similarity of maps in the synthetic dataset. These results are used to calibrate the subjective parameters in the algorithms accordingly and to generally test how well the four algorithms can perform relative to the visual comparison.

Koch, Julian; Stisen, Simon; Høgh Jensen, Karsten

2014-05-01

164

Spatial interpolation schemes of daily precipitation for hydrologic modeling  

USGS Publications Warehouse

Distributed hydrologic models typically require spatial estimates of precipitation interpolated from sparsely located observational points to the specific grid points. We compare and contrast the performance of regression-based statistical methods for the spatial estimation of precipitation in two hydrologically different basins and confirmed that widely used regression-based estimation schemes fail to describe the realistic spatial variability of daily precipitation field. The methods assessed are: (1) inverse distance weighted average; (2) multiple linear regression (MLR); (3) climatological MLR; and (4) locally weighted polynomial regression (LWP). In order to improve the performance of the interpolations, the authors propose a two-step regression technique for effective daily precipitation estimation. In this simple two-step estimation process, precipitation occurrence is first generated via a logistic regression model before estimate the amount of precipitation separately on wet days. This process generated the precipitation occurrence, amount, and spatial correlation effectively. A distributed hydrologic model (PRMS) was used for the impact analysis in daily time step simulation. Multiple simulations suggested noticeable differences between the input alternatives generated by three different interpolation schemes. Differences are shown in overall simulation error against the observations, degree of explained variability, and seasonal volumes. Simulated streamflows also showed different characteristics in mean, maximum, minimum, and peak flows. Given the same parameter optimization technique, LWP input showed least streamflow error in Alapaha basin and CMLR input showed least error (still very close to LWP) in Animas basin. All of the two-step interpolation inputs resulted in lower streamflow error compared to the directly interpolated inputs. ?? 2011 Springer-Verlag.

Hwang, Y.; Clark, M.; Rajagopalan, B.; Leavesley, G.

2012-01-01

165

Assessing model state and forecasts variation in hydrologic data assimilation  

NASA Astrophysics Data System (ADS)

Data assimilation (DA) has been widely used in hydrological models to improve model state and subsequent streamflow estimates. However, for poor or non-existent state observations, the state estimation in hydrological DA can be problematic, leading to inaccurate streamflow updates. This study evaluates the soil moisture and flow variations and forecasts by assimilating streamflow and soil moisture. Three approaches of Ensemble Kalman Filter (EnKF) with dual state-parameter estimation are applied: (1) streamflow assimilation, (2) soil moistue assimilation, and (3) combined assimilation of soil moisture and streamflow. The assimilation approaches are evaluated using the Sacramento Soil Moisture Accounting (SAC-SMA) model in the Spencer Creek catchment in southern Ontario, Canada. The results show that there are significant differences in soil moisture variations and streamflow estimates when the three assimilation approaches were applied. In the streamflow assimilation, soil moisture states were markedly distorted, particularly soil moisture of lower soil layer; whereas, in the soil moisture assimilation, streamflow estimates are inaccurate. The combined assimilation of streamflow and soil moisture provides more accurate forecasts of both soil moisture and streamflow, particularly for shorter lead times. The combined approach has the flexibility to account for model adjustment through the time variation of parameters together with state variables when soil moisture and streamflow observations are integrated into the assimilation procedure. This evaluation is important for the application of DA methods to simultaneously estimate soil moisture states and watershed response and forecasts.

Samuel, Jos; Coulibaly, Paulin; Dumedah, Gift; Moradkhani, Hamid

2014-05-01

166

Modeling Vernal Pool Hydrology and Vegetation in the Sierra Nevadas  

NASA Astrophysics Data System (ADS)

Vernal pools are geographic depressions with relatively impermeable substrates that are subject to four distinct seasons in mountainous regions: they fill with snow in the winter, melt into inundated pools in the spring, become unsaturated and vegetated by summer, then dry and become fully desiccated by fall. Vernal pools in California are greatly threatened. Over 90% of the pools in California have been destroyed by urbanization and other land use changes and continue to disappear with population growth. Furthermore, these pools face threats posed by climate change due to altered precipitation and temperature regimes. In the context of anthropogenic climate change, we are evaluating the direct and indirect effects of grazing management on ecohydrology and plant community structure in vernal pools Northern Sierra Nevada mountains. Hydrologic models of vernal pool basins, driven by climatic variables, are used to 1) determine if a changing climate will alter the magnitude and spatial distribution of inundation period within the pools; 2) determine how the available habitat for vernal pool vegetation specialists will change with climate change; 3) determine if increased soil compaction due to cattle grazing can help mitigate effects of climate change resulting from changes in hydraulic conductivity; and 4) determine the importance of spatial resolution in constructing the physical representation of the pools within the hydrologic models. Preliminary results from the models including calibration error metrics and hydroperiod impacts of grazing for models with varying spatial complexity will be presented.

Montrone, A. K.; Saito, L.; Weisberg, P.; Gosejohan, M.

2012-12-01

167

Implications of complete watershed soil moisture measurements to hydrologic modeling  

NASA Technical Reports Server (NTRS)

A series of six microwave data collection flights for measuring soil moisture were made over a small 7.8 square kilometer watershed in southwestern Minnesota. These flights were made to provide 100 percent coverage of the basin at a 400 m resolution. In addition, three flight lines were flown at preselected areas to provide a sample of data at a higher resolution of 60 m. The low level flights provide considerably more information on soil moisture variability. The results are discussed in terms of reproducibility, spatial variability and temporal variability, and their implications for hydrologic modeling.

Engman, E. T.; Jackson, T. J.; Schmugge, T. J.

1983-01-01

168

Quantifying and generalizing hydrologic responses to dam regulation using a statistical modeling approach  

NASA Astrophysics Data System (ADS)

Despite the ubiquitous existence of dams within riverscapes, much of our knowledge about dams and their environmental effects remains context-specific. Hydrology, more than any other environmental variable, has been studied in great detail with regard to dam regulation. While much progress has been made in generalizing the hydrologic effects of regulation by large dams, many aspects of hydrology show site-specific fidelity to dam operations, small dams (including diversions), and regional hydrologic regimes. A statistical modeling framework is presented as a predictive tool to quantify and generalize hydrologic responses to varying degrees of dam regulation at large spatial scales. In addition, the approach provides a method to expand sample sizes beyond that of traditional dam-hydrologic-effect analyses. Model performance was relatively poor with models explaining 10-31% of the variation in hydrologic responses. However, models had relatively high accuracies (61-89%) in classifying the direction of hydrologic responses as negative or positive. Responses of many hydrologic indices to dam regulation were highly dependent upon regional hydrology, the purpose of the dam, and the presence of diversion dams. In addition, models revealed opposite effects of dam regulation in systems regulated by individual dams versus many upstream dams, suggesting that the effects of dams may be countered by other dams in basins experiencing intensified cumulative disturbance. Results also suggested that particular contexts, including multipurpose dams, high cumulative regulation, diversions, and regions of unpredictable hydrology are all sources of increased error when predicting hydrologic responses to dams. Statistical models, such as the ones presented herein, show promise in their ability to generalize the directionality of hydrologic responses to dam regulation and provide parameter coefficients to inform future site-specific modeling efforts.

McManamay, Ryan A.

2014-11-01

169

Validating a spatially distributed hydrological model with soil morphology data  

NASA Astrophysics Data System (ADS)

Spatially distributed models are popular tools in hydrology claimed to be useful to support management decisions. Despite the high spatial resolution of the computed variables, calibration and validation is often carried out only on discharge time series at specific locations due to the lack of spatially distributed reference data. Because of this restriction, the predictive power of these models, with regard to predicted spatial patterns, can usually not be judged. An example of spatial predictions in hydrology is the prediction of saturated areas in agricultural catchments. These areas can be important source areas for inputs of agrochemicals to the stream. We set up a spatially distributed model to predict saturated areas in a 1.2 km2 catchment in Switzerland with moderate topography and artificial drainage. We translated soil morphological data available from soil maps into an estimate of the duration of soil saturation in the soil horizons. This resulted in a data set with high spatial coverage on which the model predictions were validated. In general, these saturation estimates corresponded well to the measured groundwater levels. We worked with a model that would be applicable for management decisions because of its fast calculation speed and rather low data requirements. We simultaneously calibrated the model to observed groundwater levels and discharge. The model was able to reproduce the general hydrological behavior of the catchment in terms of discharge and absolute groundwater levels. However, the the groundwater level predictions were not accurate enough to be used for the prediction of saturated areas. Groundwater level dynamics were not adequately reproduced and the predicted spatial saturation patterns did not correspond to those estimated from the soil map. Our results indicate that an accurate prediction of the groundwater level dynamics of the shallow groundwater in our catchment that is subject to artificial drainage would require a model that better represents processes at the boundary between the unsaturated and the saturated zone. However, data needed for such a more detailed model are not generally available. This severely hampers the practical use of such models despite their usefulness for scientific purposes.

Doppler, T.; Honti, M.; Zihlmann, U.; Weisskopf, P.; Stamm, C.

2014-09-01

170

Postexposure Prophylactic Effect of Hepatitis B Virus (HBV)-Active Antiretroviral Therapy against HBV Infection.  

PubMed

Retrospective study indicates that hepatitis B virus (HBV)-active nucleoside (nucleotide) analogues (NAs) used for antiretroviral therapy reduce the incidence of acute HBV infections in human immunodeficiency virus (HIV)-infected patients. Learning from HIV postexposure prophylaxis (PEP), we explored the possibility of using NAs in PEP following HBV exposure, if preexposure prophylaxis is feasible clinically. Using freshly isolated primary human hepatocytes cultured in vitro, we analyzed the effect of HBV-active tenofovir and lamivudine in primary HBV infection and also the effect of treatment with these NAs after HBV infection. HBV-active NAs applied from 24 h before inoculation could not prevent the secretion of hepatitis B surface antigen into the culture medium, and cessation of the NAs after inoculation allowed the cells to establish an apparent HBV infection. In contrast, hepatitis B immune globulin was able to prevent HBV infection completely. NA treatment before infection, however, can control the spread of HBV infection, as detected by immunohistochemistry. Practically, starting NA treatment within 2 days of primary HBV infection inhibited viral spread effectively, as well as preexposure treatment. We demonstrated that preexposure NA treatment was not able to prevent the acquisition of HBV infection but prevented viral spread by suppressing the production of mature progeny HBV virions. The effect of postexposure treatment within 2 days was similar to the effect of preexposure treatment, suggesting the possibility of HBV PEP using HBV-active NAs in HIV- and HBV-susceptible high-risk groups. PMID:25512419

Watanabe, Tsunamasa; Hamada-Tsutsumi, Susumu; Yokomaku, Yoshiyuki; Imamura, Junji; Sugiura, Wataru; Tanaka, Yasuhito

2015-02-01

171

EFFICIENT HYDROLOGICAL TRACER-TEST DESIGN (EHTD) MODEL  

EPA Science Inventory

Hydrological tracer testing is the most reliable diagnostic technique available for establishing flow trajectories and hydrologic connections and for determining basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test...

172

One-Water Hydrologic Flow Model (MODFLOW-OWHM)  

USGS Publications Warehouse

The One-Water Hydrologic Flow Model (MF-OWHM) is a MODFLOW-based integrated hydrologic flow model (IHM) that is the most complete version, to date, of the MODFLOW family of hydrologic simulators needed for the analysis of a broad range of conjunctive-use issues. Conjunctive use is the combined use of groundwater and surface water. MF-OWHM allows the simulation, analysis, and management of nearly all components of human and natural water movement and use in a physically-based supply-and-demand framework. MF-OWHM is based on the Farm Process for MODFLOW-2005 (MF-FMP2) combined with Local Grid Refinement (LGR) for embedded models to allow use of the Farm Process (FMP) and Streamflow Routing (SFR) within embedded grids. MF-OWHM also includes new features such as the Surface-water Routing Process (SWR), Seawater Intrusion (SWI), and Riparian Evapotrasnpiration (RIP-ET), and new solvers such as Newton-Raphson (NWT) and nonlinear preconditioned conjugate gradient (PCGN). This IHM also includes new connectivities to expand the linkages for deformation-, flow-, and head-dependent flows. Deformation-dependent flows are simulated through the optional linkage to simulated land subsidence with a vertically deforming mesh. Flow-dependent flows now include linkages between the new SWR with SFR and FMP, as well as connectivity with embedded models for SFR and FMP through LGR. Head-dependent flows now include a modified Hydrologic Flow Barrier Package (HFB) that allows optional transient HFB capabilities, and the flow between any two layers that are adjacent along a depositional or erosional boundary or displaced along a fault. MF-OWHM represents a complete operational hydrologic model that fully links the movement and use of groundwater, surface water, and imported water for consumption by irrigated agriculture, but also of water used in urban areas and by natural vegetation. Supply and demand components of water use are analyzed under demand-driven and supply-constrained conditions. From large- to small-scale settings, MF-OWHM has the unique set of capabilities to simulate and analyze historical, present, and future conjunctive-use conditions. MF-OWHM is especially useful for the analysis of agricultural water use where few data are available for pumpage, land use, or agricultural information. The features presented in this IHM include additional linkages with SFR, SWR, Drain-Return (DRT), Multi-Node Wells (MNW1 and MNW2), and Unsaturated-Zone Flow (UZF). Thus, MF-OWHM helps to reduce the loss of water during simulation of the hydrosphere and helps to account for “all of the water everywhere and all of the time.” In addition to groundwater, surface-water, and landscape budgets, MF-OWHM provides more options for observations of land subsidence, hydraulic properties, and evapotranspiration (ET) than previous models. Detailed landscape budgets combined with output of estimates of actual evapotranspiration facilitates linkage to remotely sensed observations as input or as additional observations for parameter estimation or water-use analysis. The features of FMP have been extended to allow for temporally variable water-accounting units (farms) that can be linked to land-use models and the specification of both surface-water and groundwater allotments to facilitate sustainability analysis and connectivity to the Groundwater Management Process (GWM). An example model described in this report demonstrates the application of MF-OWHM with the addition of land subsidence and a vertically deforming mesh, delayed recharge through an unsaturated zone, rejected infiltration in a riparian area, changes in demand caused by deficiency in supply, and changes in multi-aquifer pumpage caused by constraints imposed through the Farm Process and the MNW2 Package, and changes in surface water such as runoff, streamflow, and canal flows through SFR and SWR linkages.

Hanson, Randall T.; Boyce, Scott E.; Schmid, Wolfgang; Hughes, Joseph D.; Mehl, Steffen W.; Leake, Stanley A.; Maddock, Thomas, III; Niswonger, Richard G.

2014-01-01

173

Determining the Hydrologic Impacts of Climate Variability on Florida's Everglades Through the Use of a Finite Volume Hydrologic Model  

Microsoft Academic Search

A good understanding of climate variability and its impacts on the regional water budget are crucial for the restoration of Florida's Everglades. This is investigated by varying the two most sensitive climatic data sets, namely rainfall and evapotranspiration of a regional-scale hydrologic model. A 36-year long record, spanning from 1965 to 2000 is used in these assessments. Although not comprehensive,

S. U. Senarath; R. J. Novoa; J. M. Niedzialek; F. Zheng

2006-01-01

174

Simulation of hydrologic response in an arid and a humid watershed using a distributed hydrologic model system  

Microsoft Academic Search

Arid and humid watersheds are likely to show different spatial and temporal variation of runoff generation and groundwater table levels. In this study, we simulate and compare hydrologic response to rainfall in both the arid Lower Virgin Valley in Nevada and the humid Meiling Watershed in southeastern China, using a physically distributed watershed model system that can incorporate spatial variability

A. Baron; Z. Yu; D. Kreamer; J. Zhu

2006-01-01

175

Hydrologic modelling for climate change impacts analysis of shifts in future hydrologic regimes: implications for stream temperature and salmon habitat  

Microsoft Academic Search

The challenges faced by climate change impact analysts must be solved through interdisciplinary collaboration between research scientists, institutions and stakeholders. In particular, hydrologic modelers, climate scientists, biologists, ecologists, engineers and water resource managers must interact to pool expertise and provide tools to address the complex issues associated with future climate change. The current study examines the results of an application

K. E. Bennett; A. T. Werner; M. Schnorbus; E. P. Salathé; M. Nelitz

2009-01-01

176

A high-resolution European dataset for hydrologic modeling  

NASA Astrophysics Data System (ADS)

There is an increasing demand for large scale hydrological models not only in the field of modeling the impact of climate change on water resources but also for disaster risk assessments and flood or drought early warning systems. These large scale models need to be calibrated and verified against large amounts of observations in order to judge their capabilities to predict the future. However, the creation of large scale datasets is challenging for it requires collection, harmonization, and quality checking of large amounts of observations. For this reason, only a limited number of such datasets exist. In this work, we present a pan European, high-resolution gridded dataset of meteorological observations (EFAS-Meteo) which was designed with the aim to drive a large scale hydrological model. Similar European and global gridded datasets already exist, such as the HadGHCND (Caesar et al., 2006), the JRC MARS-STAT database (van der Goot and Orlandi, 2003) and the E-OBS gridded dataset (Haylock et al., 2008). However, none of those provide similarly high spatial resolution and/or a complete set of variables to force a hydrologic model. EFAS-Meteo contains daily maps of precipitation, surface temperature (mean, minimum and maximum), wind speed and vapour pressure at a spatial grid resolution of 5 x 5 km for the time period 1 January 1990 - 31 December 2011. It furthermore contains calculated radiation, which is calculated by using a staggered approach depending on the availability of sunshine duration, cloud cover and minimum and maximum temperature, and evapotranspiration (potential evapotranspiration, bare soil and open water evapotranspiration). The potential evapotranspiration was calculated using the Penman-Monteith equation with the above-mentioned meteorological variables. The dataset was created as part of the development of the European Flood Awareness System (EFAS) and has been continuously updated throughout the last years. The dataset variables are used as inputs to the hydrological calibration and validation of EFAS as well as for establishing long-term discharge "proxy" climatologies which can then in turn be used for statistical analysis to derive return periods or other time series derivatives. In addition, this dataset will be used to assess climatological trends in Europe. Unfortunately, to date no baseline dataset at the European scale exists to test the quality of the herein presented data. Hence, a comparison against other existing datasets can therefore only be an indication of data quality. Due to availability, a comparison was made for precipitation and temperature only, arguably the most important meteorological drivers for hydrologic models. A variety of analyses was undertaken at country scale against data reported to EUROSTAT and E-OBS datasets. The comparison revealed that while the datasets showed overall similar temporal and spatial patterns, there were some differences in magnitudes especially for precipitation. It is not straightforward to define the specific cause for these differences. However, in most cases the comparatively low observation station density appears to be the principal reason for the differences in magnitude.

Ntegeka, Victor; Salamon, Peter; Gomes, Goncalo; Sint, Hadewij; Lorini, Valerio; Thielen, Jutta

2013-04-01

177

Real Time Land-Surface Hydrologic Modeling Over Continental US  

NASA Technical Reports Server (NTRS)

The land surface component of the hydrological cycle is fundamental to the overall functioning of the atmospheric and climate processes. Spatially and temporally variable rainfall and available energy, combined with land surface heterogeneity cause complex variations in all processes related to surface hydrology. The characterization of the spatial and temporal variability of water and energy cycles are critical to improve our understanding of land surface-atmosphere interaction and the impact of land surface processes on climate extremes. Because the accurate knowledge of these processes and their variability is important for climate predictions, most Numerical Weather Prediction (NWP) centers have incorporated land surface schemes in their models. However, errors in the NWP forcing accumulate in the surface and energy stores, leading to incorrect surface water and energy partitioning and related processes. This has motivated the NWP to impose ad hoc corrections to the land surface states to prevent this drift. A proposed methodology is to develop Land Data Assimilation schemes (LDAS), which are uncoupled models forced with observations, and not affected by NWP forcing biases. The proposed research is being implemented as a real time operation using an existing Surface Vegetation Atmosphere Transfer Scheme (SVATS) model at a 40 km degree resolution across the United States to evaluate these critical science questions. The model will be forced with real time output from numerical prediction models, satellite data, and radar precipitation measurements. Model parameters will be derived from the existing GIS vegetation and soil coverages. The model results will be aggregated to various scales to assess water and energy balances and these will be validated with various in-situ observations.

Houser, Paul R.

1998-01-01

178

A new selection metric for multiobjective hydrologic model calibration  

NASA Astrophysics Data System (ADS)

novel selection metric called Convex Hull Contribution (CHC) is introduced for solving multiobjective (MO) optimization problems with Pareto fronts that can be accurately approximated by a convex curve. The hydrologic model calibration literature shows that many biobjective calibration problems with a proper setup result in such Pareto fronts. The CHC selection approach identifies a subset of archived nondominated solutions whose map in the objective space forms convex approximation of the Pareto front. The optimization algorithm can sample solely from these solutions to more accurately approximate the convex shape of the Pareto front. It is empirically demonstrated that CHC improves the performance of Pareto Archived Dynamically Dimensioned Search (PA-DDS) when solving MO problems with convex Pareto fronts. This conclusion is based on the results of several benchmark mathematical problems and several hydrologic model calibration problems with two or three objective functions. The impact of CHC on PA-DDS performance is most evident when the computational budget is somewhat limited. It is also demonstrated that 1,000 solution evaluations (limited budget in this study) is sufficient for PA-DDS with CHC-based selection to achieve very high quality calibration results relative to the results achieved after 10,000 solution evaluations.

Asadzadeh, Masoud; Tolson, Bryan A.; Burn, Donald H.

2014-09-01

179

Advances in Modeling of Coupled Hydrologic-Socioeconomic Systems  

NASA Astrophysics Data System (ADS)

River flooding is the most common natural disaster in Europe, causing deaths and huge amount of economic losses. Disastrous flood events are often related to extreme meteorological conditions; therefore, climate change is expected to have an important influence over the intensity and frequency of major floods. While approximated large-scale assessments of flood risk scenarios have been carried out, the knowledge of the effects at smaller scales is poor or incomplete, with few localized studies. Also, the methods are still coarse and uneven. The approach of this study starts from the definition of the risk paradigm and the elaboration of local climatic scenarios to track a methodology aimed at elaborating and combining the three elements concurring to the determination of risk: hydrological hazard, value exposure and vulnerability. First, hydrological hazard scenarios are provided by hydrological and hydrodynamic models, used in to a flood forecasting system capable to define "what-if" scenario in a flexible way. These results are then integrated with land-use data (exposure) and depth-damage functions (vulnerability) in a GIS environment, to assess the final risk value (potential flood damage) and visualize it in form of risk maps. In this paper results from a pilot study in the Polesine area are presented, where four simulated levee breach scenarios are compared. The outcomes of the analysis may be instrumental to authorities to increase the knowledge of possible direct losses and guide decision making and planning processes also. As future perspective, the employed methodology can also be extended at the basin scale through integration with the existent flood warning system to gain a real-time estimate of floods direct costs.

Amadio, Mattia; Mysiak, Jaroslav; Pecora, Silvano; Agnetti, Alberto

2013-04-01

180

Hydrologic Implications of Dynamical and Statistical Approaches to Downscaling Climate Model Outputs  

Microsoft Academic Search

Six approaches for downscaling climate model outputs for use in hydrologic simulation were evaluated, with particular emphasis on each method's ability to produce precipitation and other variables used to drive a macroscale hydrology model applied at much higher spatial resolution than the climate model. Comparisons were made on the basis of a twenty-year retrospective (1975–1995) climate simulation produced by the

Andrew W. Wood; Lai R. Leung; V. Sridhar; D. P. Lettenmaier

2004-01-01

181

Development and application of a spatially-distributed Arctic hydrological and thermal process model (ARHYTHM)  

Microsoft Academic Search

A process-based, spatially distributed hydrological model was developed to quantitatively simulate the energy and mass transfer processes and their interactions within arctic regions (arctic hydrological and thermal model, ARHYTHM). The model first determines the flow direction in each element, the channel drainage network and the drainage area based upon the digital elevation data. Then it simulates various physical processes: including

Ziya Zhang; Douglas L. Kane; Larry D. Hinzman

2000-01-01

182

The application of remote sensing to the development and formulation of hydrologic planning models  

NASA Technical Reports Server (NTRS)

A hydrologic planning model is developed based on remotely sensed inputs. Data from LANDSAT 1 are used to supply the model's quantitative parameters and coefficients. The use of LANDSAT data as information input to all categories of hydrologic models requiring quantitative surface parameters for their effects functioning is also investigated.

Castruccio, P. A.; Loats, H. L., Jr.; Fowler, T. R.

1976-01-01

183

Spatial calibration and temporal validation of flow for regional scale hydrologic modeling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Physically based regional scale hydrologic modeling is gaining importance for planning and management of water resources. Calibration and validation of such regional scale model is necessary before applying it for scenario assessment. However, in most regional scale hydrologic modeling, flow validat...

184

Improved Ground Hydrology Calculations for Global Climate Models (GCMs): Soil Water Movement and Evapotranspiration  

Microsoft Academic Search

A physically based ground hydrology model is developed to improve the land-surface sensible and latent heat calculations in global climate models (GCMs). The processes of transpiration, evaporation from intercepted precipitation and dew, evaporation from bare soil, infiltration, soil water flow, and runoff are explicitly included in the model. The amount of detail in the hydrologic calculations is restricted to a

F. Abramopoulos; C. Rosenzweig; B. Choudhury

1988-01-01

185

Implications of the choice and configuration of hydrologic models on the portrayal of climate change impact  

NASA Astrophysics Data System (ADS)

Climate change studies involve several methodological choices that impact the hydrological sensitivities obtained. Among these, hydrologic model structure selection and parameter identification are particularly relevant and usually have a strong subjective component. This subjectivity is not only limited to engineering applications, but also extends to many of our research studies, resulting in problems such as missing processes in our models, inappropriate parameterizations and compensatory effects of model parameters. The goal of this research is to identify the role of model structures and parameter values on the assessment of hydrologic sensitivity to climate change. We conduct our study in three basins located in the Colorado Headwaters Region, using four different hydrologic models (PRMS, VIC, Noah and Noah-MP). We first compare both model performance and climate sensitivities using default parameterizations and parameter values calibrated with the Shuffled Complex Evolution algorithm. Our results demonstrate that calibration doesn't necessarily improve the representation of hydrological processes or decrease inter-model differences in the change of signature measures of hydrologic behavior with respect to a future climate scenario. We found that inter-model differences in hydrologic sensitivities to climate change may be larger than the climate change signal even after models have been calibrated. Results demonstrate that both model choice (after calibration) and parameter selection have important effects in the portrayal of climate change impacts, and work is ongoing to identify more robust modeling strategies that explicitly account for the subjectivity in these choices. Location of the basins of interest Hydrological models used in this study

Mendoza, P. A.; Clark, M. P.; Rajagopalan, B.; Mizukami, N.; Gutmann, E. D.

2013-12-01

186

Modelling of green roof hydrological performance for urban drainage applications  

NASA Astrophysics Data System (ADS)

Green roofs are being widely implemented for stormwater management and their impact on the urban hydrological cycle can be evaluated by incorporating them into urban drainage models. This paper presents a model of green roof long term and single event hydrological performance. The model includes surface and subsurface storage components representing the overall retention capacity of the green roof which is continuously re-established by evapotranspiration. The runoff from the model is described through a non-linear reservoir approach. The model was calibrated and validated using measurement data from 3 different extensive sedum roofs in Denmark. These data consist of high-resolution measurements of runoff, precipitation and atmospheric variables in the period 2010-2012. The hydrological response of green roofs was quantified based on statistical analysis of the results of a 22-year (1989-2010) continuous simulation with Danish climate data. The results show that during single events, the 10 min runoff intensities were reduced by 10-36% for 5-10 years return period and 40-78% for 0.1-1 year return period; the runoff volumes were reduced by 2-5% for 5-10 years return period and 18-28% for 0.1-1 year return period. Annual runoff volumes were estimated to be 43-68% of the total precipitation. The peak time delay was found to greatly vary from 0 to more than 40 min depending on the type of event, and a general decrease in the time delay was observed for increasing rainfall intensities. Furthermore, the model was used to evaluate the variation of the average annual runoff from green roofs as a function of the total available storage and vegetation type. The results show that even a few millimeters of storage can reduce the mean annual runoff by up to 20% when compared to a traditional roof and that the mean annual runoff is not linearly related to the storage. Green roofs have therefore the potential to be important parts of future urban stormwater management plans.

Locatelli, Luca; Mark, Ole; Mikkelsen, Peter Steen; Arnbjerg-Nielsen, Karsten; Bergen Jensen, Marina; Binning, Philip John

2014-11-01

187

A hydrologic and geomorphic model of estuary breaching and closure  

NASA Astrophysics Data System (ADS)

To better understand how the hydrology of bar-built estuaries affects breaching and closing patterns, a model is developed that incorporates an estuary hydrologic budget with a geomorphic model of the inlet system. Erosion of the inlet is caused by inlet flow, whereas the only morphologic effect of waves is the deposition of sand into the inlet. When calibrated, the model is able to reproduce the initial seasonal breaching, seasonal closure, intermittent closures and breaches, and the low-streamflow (closed state) estuary hydrology of the Carmel Lagoon, located in Central California. Model performance was tested against three separate years of water-level observations. When open during these years, the inlet was visually observed to drain directly across the beach berm, in accordance with model assumptions. The calibrated model predicts the observed 48-h estuary stage amplitude with root mean square errors of 0.45 m, 0.39 m and 0.42 m for the three separate years. For the calibrated model, the probability that the estuary inlet is closed decreases exponentially with increasing inflow (streamflow plus wave overtopping), decreasing 10-fold in probability as mean daily inflow increases from 0.2 to 1.0 m3/s. Seasonal patterns of inlet state reflect the seasonal pattern of streamflow, though wave overtopping may become the main hydrologic flux during low streamflow conditions, infrequently causing short-lived breaches. In a series of sensitivity analyses it is seen that the status of the inlet and storage of water are sensitive to factors that control the storage, transmission, and inflow of water. By varying individual components of the berm system and estuary storage, the amount of the time the estuary is open may increase by 57%, or decrease by 44%, compared to the amount of time the estuary is open during calibrated model conditions for the 18.2-year model period. The individual components tested are: berm height, width, length, and hydraulic conductivity; estuary hypsometry (storage to stage relationship); two factors that control wave-swash sedimentation of the inlet; and sea level rise. The elevation of the berm determines the volume of water that must enter the estuary in order to breach, and it modulates the wave-overtopping flux and frequency. By increasing estuary storage capacity, the estuary will breach less frequently (- 27% change in time open for modeled excavation scenario) and store water up to 3 months later into the summer. Altering beach aquifer hydraulic conductivity affects inlet state, and patterns of breaching and water storage. As a result of sea-level rise of 1.67 m by 2100, and a beach berm that remains in its current location and accretes vertically, the amount of time the estuary remains open may decrease by 44%. Such a change is an end-member of likely scenarios given that the berm will translate landwards. Model results indicate that the amount of time the estuary is open is more sensitive to changes in wave run-up than the amount of sand deposited in the inlet per each overtopping wave.

Rich, Andrew; Keller, Edward A.

2013-06-01

188

Neural Network Hydrological Modelling: Linear Output Activation Functions?  

NASA Astrophysics Data System (ADS)

The power to represent non-linear hydrological processes is of paramount importance in neural network hydrological modelling operations. The accepted wisdom requires non-polynomial activation functions to be incorporated in the hidden units such that a single tier of hidden units can thereafter be used to provide a 'universal approximation' to whatever particular hydrological mechanism or function is of interest to the modeller. The user can select from a set of default activation functions, or in certain software packages, is able to define their own function - the most popular options being logistic, sigmoid and hyperbolic tangent. If a unit does not transform its inputs it is said to possess a 'linear activation function' and a combination of linear activation functions will produce a linear solution; whereas the use of non-linear activation functions will produce non-linear solutions in which the principle of superposition does not hold. For hidden units, speed of learning and network complexities are important issues. For the output units, it is desirable to select an activation function that is suited to the distribution of the target values: e.g. binary targets (logistic); categorical targets (softmax); continuous-valued targets with a bounded range (logistic / tanh); positive target values with no known upper bound (exponential; but beware of overflow); continuous-valued targets with no known bounds (linear). It is also standard practice in most hydrological applications to use the default software settings and to insert a set of identical non-linear activation functions in the hidden layer and output layer processing units. Mixed combinations have nevertheless been reported in several hydrological modelling papers and the full ramifications of such activities requires further investigation and assessment i.e. non-linear activation functions in the hidden units connected to linear or clipped-linear activation functions in the output unit. There are two obvious advantages related to the use of a linear activation function in the output unit: (i) to restrict potential impacts and distortions associated with upper limit and lower limit saturation effects; and (ii) to address potential deficiencies and ceilings associated with undershoots or requirements to extrapolate beyond the range of the training dataset. The harmful side effects of using linear as opposed to non-linear activation functions in the output unit will be reported in this paper based on an investigation of six-hour timestep operational river level forecasting for the Skelton Gauging Station [Station No: 027009; Grid Ref: SE 568 554] on the River Ouse in England. The power to develop simple near-linear one-step-ahead forecasts remained more or less unchanged; whereas the challenge to develop more demanding non-linear four-step-ahead forecasts revealed major shortcomings related to the implementation of a linear activation function in the output unit of a parsimonious neural network model.

Abrahart, R. J.; Dawson, C. W.

2005-12-01

189

Hydrological modelling of slopes from field monitoring data  

NASA Astrophysics Data System (ADS)

A simplified hydrological model of a steep slope covered with loose granular pyroclastic deposits is presented. The slope is located in the mountains northern of Naples, and the soil cover, constituted by layers of loose volcanic ashes and pumices with a total thickness of 2.5m, lays upon a fractured limestone bedrock. At the interface between the bedrock and the soil cover, a layer of weathered ashes, with significant clay fraction, is sometimes observed. The slope has a fairly regular inclination of 40°, and is covered by chestnut woods and thick brushwood growing in late spring. The inclination of the slope is comparable with the internal friction angle of the ashes, thus the equilibrium is possible thanks to the contribution offered to the shear strength by the soil suction in unsaturated conditions. Indeed, in December 1999, a landslide was triggered by prolonged and intense precipitations. As it frequently happens with similar pyroclastic covers, the triggered slide exhibited a flow-like behavior, covering 2km in few minutes, heavily hitting the nearby town of Cervinara (AV). Since then, the slope has been constantly monitored, and during the last two years an automated station with seven TDR probes for the measurement of soil water content, eight tensiometers for the measurement of soil suction, and a rain gauge, has been operating. The data, collected every two hours, allowed getting more insight of the hydrological behavior of the slope and building up an effective hydrological model. In the model, the layered soil profile has been replaced with a single homogeneous layer, with water retention curve estimated by coupling the values of water content and suction measured at various depths. A seasonal top boundary condition has been introduced, related to the annual cycle of the vegetation: the observed precipitations quickly caused changes of soil suction at the depth of -50cm during the entire year, with the exception of the period between the end of May and the early August. To reproduce the observed behavior of soil suction at the bottom of the profile, a linear reservoir model has been introduced as bottom boundary condition, related to the presence of a small aquifer in the fractured bedrock, which water table, affecting the hydraulic conditions of the soil cover, rapidly deepens during the dry season. The developed model, calibrated with the data of one year of observation, satisfactorily reproduces the observed soil hydraulic behaviour also during other periods.

Comegna, Luca; Damiano, Emilia; Greco, Roberto; Guida, Andrea; Olivares, Lucio; Picarelli, Luciano

2013-04-01

190

Parameterisation, calibration and validation of distributed hydrological models  

NASA Astrophysics Data System (ADS)

This paper emphasizes the different requirements for calibration and validation of lumped and distributed models. On the basis of a theoretically founded modelling protocol, the different steps in distributed hydrological modelling are illustrated through a case study based on the MIKE SHE code and the 440 km 2 Karup catchment in Denmark. The importance of a rigorous and purposeful parameterisation is emphasized in order to get as few "free" parameters as possible for which assessments through calibration are required. Calibration and validation using a split-sample procedure were carried out for catchment discharge and piezometric heads at seven selected observation wells. The validated model was then used for two further validation tests. Firstly, model simulations were compared with observations from three additional discharge sites and four additional wells located within the catchment. This internal validation showed significantly poorer results compared to the calibration/validation sites. Secondly, the validated model based on a 500 m model grid was used to generate three additional models with 1000 m, 2000 m and 4000 m grids through interpolation of model parameters. The results from the multi-scale validation suggested that a maximum grid size of 1000 m should be used for simulations of discharge and ground-water heads, while the results deteriorated with coarser model grids.

Refsgaard, Jens Christian

1997-11-01

191

Ecological Acclimation and Hydrologic Response: Problem Complexity and Modeling Challenges  

NASA Astrophysics Data System (ADS)

Elevated CO2 in the atmosphere leads to a number of acclimatory responses in different vegetation types. These may be characterized as structural such as vegetation height or foliage density, ecophysiological such as reduction in stomatal conductance, and biochemical such as photosynthetic down-regulation. Furthermore, the allocation of assimilated carbon to different vegetation parts such as leaves, roots, stem and seeds is also altered such that empirical allometric relations are no longer valid. The extent and nature of these acclimatory responses vary between C3 and C4 vegetation and across species. These acclimatory responses have significant impact on hydrologic fluxes both pertaining to water and energy with the possibility of large-scale hydrologic influence. Capturing the pathways of acclimatory response to provide accurate ecohydrologic response predictions requires incorporating subtle relationships that are accentuated under elevated CO2. The talk will discuss the challenges of modeling these as well as applications to soybean, maize and bioenergy crops such as switchgrass and miscanthus.

Kumar, P.; Srinivasan, V.; Le, P. V. V.; Drewry, D.

2012-04-01

192

Building Community Around Hydrologic Data Models Within CUAHSI  

NASA Astrophysics Data System (ADS)

The Consortium of Universities for the Advancement of Hydrologic Science, Inc (CUAHSI) has a Hydrologic Information Systems project which aims to provide better data access and capacity for data synthesis for the nation's water information, both that collected by academic investigators and that collected by water agencies. These data include observations of streamflow, water quality, groundwater levels, weather and climate and aquatic biology. Each water agency or research investigator has a unique method of formatting their data (syntactic heterogeneity) and describing their variables (semantic heterogeneity). The result is a large agglomeration of data in many formats and descriptions whose full content is hard to interpret and analyze. CUAHSI is helping to resolve syntactic heterogeneity through the development of WaterML, a standard XML markup language for communicating water observations data through web services, and a standard relational database structure for archiving data called the Observations Data Model. Variables in these data archiving and communicating systems are indexed against a controlled vocabulary of descriptive terms to provide the capacity to synthesize common data types from disparate data sources.

Maidment, D.

2007-12-01

193

Testing calibration routines for LISFLOOD, a distributed hydrological model  

NASA Astrophysics Data System (ADS)

Traditionally hydrological models are considered as difficult to calibrate: their highly non-linearity results in rugged and rough response surfaces were calibration algorithms easily get stuck in local minima. For the calibration of distributed hydrological models two extra factors play an important role: on the one hand they are often costly on computation, thus restricting the feasible number of model runs; on the other hand their distributed nature smooths the response surface, thus facilitating the search for a global minimum. Lisflood is a distributed hydrological model currently used for the European Flood Alert System - EFAS (Van der Knijff et al, 2008). Its upcoming recalibration over more then 200 catchments, each with an average runtime of 2-3 minutes, proved a perfect occasion to put several existing calibration algorithms to the test. The tested routines are Downhill Simplex (DHS, Nelder and Mead, 1965), SCEUA (Duan et Al. 1993), SCEM (Vrugt et al., 2003) and AMALGAM (Vrugt et al., 2008), and they were evaluated on their capability to efficiently converge onto the global minimum and on the spread in the found solutions in repeated runs. The routines were let loose on a simple hyperbolic function, on a Lisflood catchment using model output as observation, and on two Lisflood catchments using real observations (one on the river Inn in the Alps, the other along the downstream stretch of the Elbe). On the mathematical problem and on the catchment with synthetic observations DHS proved to be the fastest and the most efficient in finding a solution. SCEUA and AMALGAM are a slower, but while SCEUA keeps converging on the exact solution, AMALGAM slows down after about 600 runs. For the Lisflood models with real-time observations AMALGAM (hybrid algorithm that combines several other algorithms, we used CMA, PSO and GA) came as fastest out of the tests, and giving comparable results in consecutive runs. However, some more work is needed to tweak the stopping criteria. SCEUA is a bit slower, but has very transparent stopping rules. Both have closed in on the minima after about 600 runs. DHS equals only SCEUA on convergence speed. The stopping criteria we applied so far are too strict, causing it to stop too early. SCEM converges 5-6 times slower. This is a high price for the parameter uncertainty analysis that is simultaneously done. The ease with which all algorithms find the same optimum suggests that we are dealing with a smooth and relatively simple response surface. This leaves room for other deterministic calibration algorithms being smarter than DHS in sliding downhill. PEST seems promising but sofar we haven't managed to get it running with LISFLOOD. • Duan, Q.; Gupta, V. & Sorooshian, S., 1993, Shuffled complex evolution approach for effective and efficient global minimization, J Optim Theory Appl, Kluwer Academic Publishers-Plenum Publishers, 76, 501-521 • Nelder, J. & Mead, R., 1965, A simplex method for function minimization, Comput. J., 7, 308-313 • Van Der Knijff, J. M.; Younis, J. & De Roo, A. P. J., 2008, LISFLOOD: a GIS-based distributed model for river basin scale water balance and flood simulation, International Journal of Geographical Information Science, • Vrugt, J.; Gupta, H.; Bouten, W. & Sorooshian, S., 2003, A Shuffled Complex Evolution Metropolis algorithm for optimization and uncertainty assessment of hydrologic model parameters, Water Resour. Res., 39 • Vrugt, J.; Robinson, B. & Hyman, J., 2008, Self-Adaptive Multimethod Search for Global Optimization in Real-Parameter Spaces, IEEE Trans Evol Comput, IEEE,

Pannemans, B.

2009-04-01

194

Chimeric hepatitis B virus (HBV)/hepatitis C virus (HCV) subviral envelope particles induce efficient anti-HCV antibody production in animals pre-immunized with HBV vaccine.  

PubMed

The development of an effective, affordable prophylactic vaccine against hepatitis C virus (HCV) remains a medical priority. The recently described chimeric HBV-HCV subviral envelope particles could potentially be used for this purpose, as they could be produced by industrial procedures adapted from those established for the hepatitis B virus (HBV) vaccine. We show here, in an animal model, that pre-existing immunity acquired through HBV vaccination does not influence the immunogenicity of the HCV E2 protein presented by these chimeric particles. Thus, these chimeric HBV-HCV subviral envelope particles could potentially be used as a booster in individuals previously vaccinated against HBV, to induce protective immunity to HCV. PMID:25596457

Beaumont, Elodie; Roingeard, Philippe

2015-02-18

195

GIS embedded hydrological modeling: the SID&GRID project  

NASA Astrophysics Data System (ADS)

The SID&GRID research project, started April 2010 and funded by Regione Toscana (Italy) under the POR FSE 2007-2013, aims to develop a Decision Support System (DSS) for water resource management and planning based on open source and public domain solutions. In order to quantitatively assess water availability in space and time and to support the planning decision processes, the SID&GRID solution consists of hydrological models (coupling 3D existing and newly developed surface- and ground-water and unsaturated zone modeling codes) embedded in a GIS interface, applications and library, where all the input and output data are managed by means of DataBase Management System (DBMS). A graphical user interface (GUI) to manage, analyze and run the SID&GRID hydrological models based on open source gvSIG GIS framework (Asociación gvSIG, 2011) and a Spatial Data Infrastructure to share and interoperate with distributed geographical data is being developed. Such a GUI is thought as a "master control panel" able to guide the user from pre-processing spatial and temporal data, running the hydrological models, and analyzing the outputs. To achieve the above-mentioned goals, the following codes have been selected and are being integrated: 1. Postgresql/PostGIS (PostGIS, 2011) for the Geo Data base Management System; 2. gvSIG with Sextante (Olaya, 2011) geo-algorithm library capabilities and Grass tools (GRASS Development Team, 2011) for the desktop GIS; 3. Geoserver and Geonetwork to share and discover spatial data on the web according to Open Geospatial Consortium; 4. new tools based on the Sextante GeoAlgorithm framework; 5. MODFLOW-2005 (Harbaugh, 2005) groundwater modeling code; 6. MODFLOW-LGR (Mehl and Hill 2005) for local grid refinement; 7. VSF (Thoms et al., 2006) for the variable saturated flow component; 8. new developed routines for overland flow; 9. new algorithms in Jython integrated in gvSIG to compute the net rainfall rate reaching the soil surface, as input for the unsaturated/saturated flow model. At this stage of the research (which will end April 2013), two primary components of the master control panel are being developed: i. a SID&GRID toolbar integrated into gvSIG map context; ii. a new Sextante set of geo-algorithm to pre- and post-process the spatial data to run the hydrological models. The groundwater part of the code has been fully integrated and tested and 3D visualization tools are being developed. The LGR capability has been extended to the 3D solution of the Richards' equation in order to solve in detail the unsaturated zone where required. To be updated about the project, please follow us at the website: http://ut11.isti.cnr.it/SIDGRID/

Borsi, I.; Rossetto, R.; Schifani, C.

2012-04-01

196

Modelling floods in theAmmer catchment:limitations and challenges with a coupled meteo-hydrological model approach Hydrology and Earth System Sciences, 7(6), 833847 (2003) EGU  

E-print Network

Modelling floods in theAmmer catchment:limitations and challenges with a coupled meteo-hydrological model approach 833 Hydrology and Earth System Sciences, 7(6), 833847 (2003) © EGU Modelling floods in the Ammer catchment: limitations and challenges with a coupled meteo-hydrological model approach R. Ludwig1

Paris-Sud XI, Université de

197

Hydrologic Modeling of the White Sands Dune Field, New Mexico  

NASA Astrophysics Data System (ADS)

The shallow groundwater flow system of White Sands dune field, located within the Tularosa Basin of Southern New Mexico, likely stabilizes the base of the largest gypsum dunefield in the world. Water table geometry and elevation play a critical role in controlling dune thickness, spatial extent, and migration rates. The White Sands National Monument (WHSA) is concerned that lowering the water table may lead to increased scour and migration of the dune field, which could be unfavorable to the preservation of the flora and fauna that have adapted to survive there. In response to projected increases in groundwater pumping in the regional Tularosa Basin groundwater system, changes in surface water use, and the threat of climate change, the WHSA is interested in understanding how these changes on a regional scale may impact the shallow dune aquifer. We have collected hydrological, geochemical, and geophysical data in order to identify the sources of recharge that contribute to the shallow dune aquifer and to assess interactions between this water table aquifer and the basin-scale, regional system. Vertical head gradients, temperature, and water quality data strongly suggest that local precipitation is the primary source of recharge to the dune aquifer today. This suggests that the modern dune system is relatively isolated from the deeper regional system. However, geochemical and electrical resistivity data indicates that the deeper basin groundwater system does contribute to the shallow system and suggests that hydrologic conditions have changed on geologic time scales. We have constructed a preliminary cross-sectional hydrologic model to attempt to characterize the interaction of the shallow dune aquifer with the deeper basin groundwater. The model cross-section extends about 80 km across the Tularosa Basin in a NW-SE direction parallel to the primary flow path. We represented 6 km of Precambrian crystalline basement, Paleozoic sedimentary rocks as well as Pleistocene and Quaternary units. Preliminary results indicate a component of deep groundwater flows to a depth of 5 km and is discharged near Lake Lucero located west of the WHSA. Computed and observed salinity and groundwater residence times are the primary means of model calibration. The results will allow for an improved understanding of the interaction between the basin- and dune-scale groundwater flow systems.

Bourret, S. M.; Newton, B. T.; Person, M. A.

2013-12-01

198

Improved cavity detection from coupled seismic and hydrologic models  

NASA Astrophysics Data System (ADS)

Seismic methods hold much promise for cavity detection, but the results from field measurements have been frustratingly inconsistent between field sites. The reasons for the inconsistencies are not fully understood, though water saturation in the near-surface may be responsible to some extent. The conventional approach has been to focus on reflections and refractions generated from the impedance contrast of the cavity wall itself, where the dimensions and geometry of the cavity should play key roles. Here, we instead focus on the influence of impedance contrasts that are generated by hydrologic processes in the adjacent porous medium. These contrasts can potentially increase or decrease the reflection/refraction footprint of the cavity itself. Detectable hydrologic anomalies can be created by the simple drainage of groundwater into the cavity (initially saturated conditions) or by the creation of a capillary barrier around the cavity (initially unsaturated conditions). Because both processes ultimately involve unsaturated conditions we use HYDRUS 2D to numerically solve the Richard's equation and simulate flow through the vadose zone. Using the generated soil moisture information and Brutsaert's (1964) saturation-velocity relation, we constructed velocity models. Our simulations suggest several scenarios where changes in saturation due to the cavity may be utilized to enhance cavity detection with seismic waves. One simulation is for unsaturated conditions in the top 10 meters of soil, where capillary forces exert a major influence on velocity. In this case, the impedance contrast is greatest for near-saturated soils. Deeper cavities (100s of meters) in permeable saturated materials are also favorable due to the sharp impedance contrast between saturated and unsaturated material. Our hydrology-determined velocity models are then used in finite-difference wave propagation simulations to determine the effects on seismic waves at various depths and saturations. Saturation features in the seismic data can then be utilized to detect cavities rather than relying on traditional yet inconsistent reflection/refraction approach. In ongoing work, we will ground-truth these models with both laboratory and experimental results. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Desilets, S.; Bonal, N. D.; Desilets, D.

2012-12-01

199

Parameterization of potential evapotranspiration approaches for distributed hydrologic modeling  

NASA Astrophysics Data System (ADS)

Reliable soil moisture products are needed for the estimation of plant available water or agricultural droughts. For the simulation of hydrological states, e.g. soil moisture, the estimation of evapotranspiration is crucial since it has the largest contribution to the water balance besides precipitation. In hydrological modeling the evapotranspiration is usually estimated based on potential evapotranspiration (PET). The common approaches for PET estimation and their parameterization are sufficient at the point or field scale for which they have been developed. But for spatially distributed estimations on the mesoscale, e.g. 4 km, their robust parameterization is still a challenge in current research. The aim of this study is to find scale and location independent parameters for three different potential evapotranspiration formulations, which are applied in the mesoscale Hydrologic Model (mHM). PET is estimated using the 1) Hargreaves-Samani, 2) Priestley-Taylor, and 3) Penman-Monteith equations. The Hargreaves-Samani method is a temperature driven approach, whereas the other two methods are based on radiation. For estimating the parameters of the above mentioned PET formulations, the Multiscale Parameter Regionalization technique is used. This technique accounts for subgrid variabilities by connecting morphological terrain properties, which are available in a higher resolution than the model resolution, with the parameters for the particular PET approach. The parameters, which needed to be estimated, are the coefficient of the Hargreaves-Samani equation, the Priestley-Taylor coefficient, and the aerodynamic and bulk surface resistance for the Penman-Monteith equation. The Hargreaves-Samani coefficient is regionalized based on the aspect of the terrain. The Priestley-Taylor coefficient as well as the aerodynamic and bulk surface resistance have been estimated using static land cover information combined with leaf area index (LAI) development curves and thus an approximation for vegetation information. This new parameterized PET approaches are evaluated in six different German river basins ranging from 6,000 km2 to 38,000 km2 including a spatial variety from catchments in the northern German lowlands to alpine catchments in the south. The comparison of the results is focusing on evapotranspiration, soil moisture and discharge. Whereas only slight changes in the discharge hydrograph have been observed in the comparison of the three PET equations, the impact on soil moisture is significant. Especially during the summer period the soil moisture is lower for the Priestley-Taylor and Penman-Monteith formulation compared to the Hargreaves-Samani equation. This effect is due to higher estimates in PET for those two methods. Furthermore a validation against eddy covariance measurements showed that the dynamics of evapotranspiration is captured well by the three methods.

Zink, Matthias; Mai, Juliane; Cuntz, Matthias; Samaniego, Luis

2014-05-01

200

Modelling hydrological processes in mesoscale lowland river basins with SWAT—capabilities and challenges  

Microsoft Academic Search

Lowland areas are characterized by specific properties, such as flat topography, low hydraulic gradients, shallow groundwater, and high potential for water retention in peatland and lakes. These characteristics and their dominating hydrological processes have to be assessed and considered for the analysis and modelling of water balances in lowland catchments. The capabilities and challenges of modelling hydrological processes and water

BRITTA SCHMALZ; FILIPA TAVARES; NICOLA FOHRER

2008-01-01

201

HYDROLOGIC EVALUATION OF LANDFILL PERFORMANCE (HELP) MODEL: USER'S GUIDE FOR VERSION 3  

EPA Science Inventory

The Hydrologic Evaluation of Landfill Performance (HELP) computer program is a quasi-two-dimensional hydrologic model of water movement across, into, through and out of landfills. he model accepts weather, soil and design data. andfill systems including various combinations of ve...

202

Hydroclimatic Analysis of a Carbonate Island Pond Through the Development of a Hydrologic Landscape Unit Model  

Microsoft Academic Search

The purpose of this study is to develop a methodology that allows for an esti- mate of the hydroclimatic influence on an inland pond system on San Salvador, Bahamas. The methodology utilizes the Hydrologic Landscape Unit (HLU) model, a new conceptual model that offers hydrologists and water-resource managers more flexibility in representing the components of the unique and complex hydrologic

Michael A. Crump; Douglas W. Gamble

2006-01-01

203

Stimulation from Simulation? A Teaching Model of Hillslope Hydrology for Use on Microcomputers.  

ERIC Educational Resources Information Center

The design and use of a simple computer model which simulates a hillslope hydrology is described in a teaching context. The model shows a relatively complex environmental system can be constructed on the basis of a simple but realistic theory, thus allowing students to simulate the hydrological response of real hillslopes. (Author/TRS)

Burt, Tim; Butcher, Dave

1986-01-01

204

Investigation of Hydrological Variability in West Africa Using Land Surface Models  

Microsoft Academic Search

The availability of freshwater is a particularly important issue in Africa where large portions of the continent are arid or semiarid and climate is highly variable. Sustainable water resource management requires the assessment of hydrological variability in response to nature climate fluctuation. In this study, a land surface model, the Integrated Biosphere Simulator (IBIS), and a hydrological routing model, the

K. Y. Li; M. T. Coe; N. Ramankutty

2005-01-01

205

Multiobjective sensitivity analysis and optimization of distributed hydrologic model MOBIDIC  

NASA Astrophysics Data System (ADS)

Calibration of distributed hydrologic models usually involves how to deal with the large number of distributed parameters and optimization problems with multiple but often conflicting objectives that arise in a natural fashion. This study presents a multiobjective sensitivity and optimization approach to handle these problems for the MOBIDIC (MOdello di Bilancio Idrologico DIstribuito e Continuo) distributed hydrologic model, which combines two sensitivity analysis techniques (the Morris method and the state-dependent parameter (SDP) method) with multiobjective optimization (MOO) approach ?-NSGAII (Non-dominated Sorting Genetic Algorithm-II). This approach was implemented to calibrate MOBIDIC with its application to the Davidson watershed, North Carolina, with three objective functions, i.e., the standardized root mean square error (SRMSE) of logarithmic transformed discharge, the water balance index, and the mean absolute error of the logarithmic transformed flow duration curve, and its results were compared with those of a single objective optimization (SOO) with the traditional Nelder-Mead simplex algorithm used in MOBIDIC by taking the objective function as the Euclidean norm of these three objectives. Results show that (1) the two sensitivity analysis techniques are effective and efficient for determining the sensitive processes and insensitive parameters: surface runoff and evaporation are very sensitive processes to all three objective functions, while groundwater recession and soil hydraulic conductivity are not sensitive and were excluded in the optimization. (2) Both MOO and SOO lead to acceptable simulations; e.g., for MOO, the average Nash-Sutcliffe value is 0.75 in the calibration period and 0.70 in the validation period. (3) Evaporation and surface runoff show similar importance for watershed water balance, while the contribution of baseflow can be ignored. (4) Compared to SOO, which was dependent on the initial starting location, MOO provides more insight into parameter sensitivity and the conflicting characteristics of these objective functions. Multiobjective sensitivity analysis and optimization provide an alternative way for future MOBIDIC modeling.

Yang, J.; Castelli, F.; Chen, Y.

2014-10-01

206

Modeling Floodplain Inundation by Integration of Hydrological With Hydraulic Model, Case Study: Muda River, Kedah  

Microsoft Academic Search

River flood is recurrent natural phenomena in tropics and sub tropical climate. Among all kinds of natural hazards of the world flood is probably most wide spread, frequent and destructive. In recent years, remote sensing and GIS has become the key tool for flood modeling. This paper will discuss the modeling of floodplain by integrated hydrological with hydraulic model. The

RABIE ALI HUSSEIN; AMINUDDIN AB; NOR AZAZI ZAKARIA; SANUSI S. AHMAD; ZORKEFLEE ABU HASAN

207

Bayesian Inference of the Evolution of HBV/E  

PubMed Central

Despite its wide spread and high prevalence in sub-Saharan Africa, hepatitis B virus genotype E (HBV/E) has a surprisingly low genetic diversity, indicating an only recent emergence of this genotype in the general African population. Here, we performed extensive phylogeographic analyses, including Bayesian MCMC modeling. Our results indicate a mutation rate of 1.9×10?4 substitutions per site and year (s/s/y) and confirm a recent emergence of HBV/E, most likely within the last 130 years, and only after the transatlantic slave-trade had come to an end. Our analyses suggest that HBV/E originated from the area of Nigeria, before rapidly spreading throughout sub-Saharan Africa. Interestingly, viral strains found in Haiti seem to be the result of multiple introductions only in the second half of the 20th century, corroborating an absence of a significant number of HBV/E strains in West Africa several centuries ago. Our results confirm that the hyperendemicity of HBV(E) in today's Africa is a recent phenomenon and likely the result of dramatic changes in the routes of viral transmission in a relatively recent past. PMID:24312336

Andernach, Iris E.; Hunewald, Oliver E.; Muller, Claude P.

2013-01-01

208

A METHODOLOGY FOR ESTIMATING UNCERTAINTY OF A DISTRIBUTED HYDROLOGIC MODEL: APPLICATION TO POCONO CREEK WATERSHED  

EPA Science Inventory

Utility of distributed hydrologic and water quality models for watershed management and sustainability studies should be accompanied by rigorous model uncertainty analysis. However, the use of complex watershed models primarily follows the traditional {calibrate/validate/predict}...

209

Dynamic Neural Networks for Nonstationary Hydrological Time Series Modeling  

Microsoft Academic Search

Evidence of nonstationary trends in hydrological time series, which result from natural and\\/or anthropogenic climatic variability\\u000a and change, has raised a number of questions as to the adequacy of conventional statistical methods for long-term (seasonal\\u000a to annual) hydrologic time series forecasting. Most conventional statistical methods that are used in hydrology will suffer\\u000a from severe limitations as they assume a stationary

P. Coulibaly; C. K. Baldwin

210

Upscaling from research watersheds: an essential stage of trustworthy general-purpose hydrologic model building  

NASA Astrophysics Data System (ADS)

Highly instrumented research watersheds provide excellent opportunities for investigating hydrologic processes. A danger, however, is that the processes observed at a particular research watershed are too specific to the watershed and not representative even of the larger scale watershed that contains that particular research watershed. Thus, models developed based on those partial observations may not be suitable for general hydrologic use. Therefore demonstrating the upscaling of hydrologic process from research watersheds to larger watersheds is essential to validate concepts and test model structure. The Hydrograph model has been developed as a general-purpose process-based hydrologic distributed system. In its applications and further development we evaluate the scaling of model concepts and parameters in a wide range of hydrologic landscapes. All models, either lumped or distributed, are based on a discretization concept. It is common practice that watersheds are discretized into so called hydrologic units or hydrologic landscapes possessing assumed homogeneous hydrologic functioning. If a model structure is fixed, the difference in hydrologic functioning (difference in hydrologic landscapes) should be reflected by a specific set of model parameters. Research watersheds provide the possibility for reasonable detailed combining of processes into some typical hydrologic concept such as hydrologic units, hydrologic forms, and runoff formation complexes in the Hydrograph model. And here by upscaling we imply not the upscaling of a single process but upscaling of such unified hydrologic functioning. The simulation of runoff processes for the Dry Creek research watershed, Idaho, USA (27 km2) was undertaken using the Hydrograph model. The information on the watershed was provided by Boise State University and included a GIS database of watershed characteristics and a detailed hydrometeorological observational dataset. The model provided good simulation results in terms of runoff and variable states of soil and snow over a simulation period 2000 - 2009. The parameters of the model were hand-adjusted based on rational sense, observational data and available understanding of underlying processes. For the first run some processes as riparian vegetation impact on runoff and streamflow/groundwater interaction were handled in a conceptual way. It was shown that the use of Hydrograph model which requires modest amount of parameter calibration may serve also as a quality control for observations. Based on the obtained parameters values and process understanding at the research watershed the model was applied to the larger scale watersheds located in similar environment - the Boise River at South Fork (1660 km2) and Twin Springs (2155 km2). The evaluation of the results of such upscaling will be presented.

McNamara, J. P.; Semenova, O.; Restrepo, P. J.

2011-12-01

211

Multi-model ensemble hydrologic prediction and uncertainties analysis  

NASA Astrophysics Data System (ADS)

Modelling uncertainties (i.e. input errors, parameter uncertainties and model structural errors) inevitably exist in hydrological prediction. A lot of recent attention has focused on these, of which input error modelling, parameter optimization and multi-model ensemble strategies are the three most popular methods to demonstrate the impacts of modelling uncertainties. In this paper the Xinanjiang model, the Hybrid rainfall-runoff model and the HYMOD model were applied to the Mishui Basin, south China, for daily streamflow ensemble simulation and uncertainty analysis. The three models were first calibrated by two parameter optimization algorithms, namely, the Shuffled Complex Evolution method (SCE-UA) and the Shuffled Complex Evolution Metropolis method (SCEM-UA); next, the input uncertainty was accounted for by introducing a normally-distributed error multiplier; then, the simulation sets calculated from the three models were combined by Bayesian model averaging (BMA). The results show that both these parameter optimization algorithms generate good streamflow simulations; specifically the SCEM-UA can imply parameter uncertainty and give the posterior distribution of the parameters. Considering the precipitation input uncertainty, the streamflow simulation precision does not improve very much. While the BMA combination not only improves the streamflow prediction precision, it also gives quantitative uncertainty bounds for the simulation sets. The SCEM-UA calculated prediction interval is better than the SCE-UA calculated one. These results suggest that considering the model parameters' uncertainties and doing multi-model ensemble simulations are very practical for streamflow prediction and flood forecasting, from which more precision prediction and more reliable uncertainty bounds can be generated.

Jiang, S.; Ren, L.; Yang, X.; Ma, M.; Liu, Y.

2014-09-01

212

Large Scale Hydrological Modelling: Parameterisation of Groundwater Recharge  

NASA Astrophysics Data System (ADS)

There is currently worldwide interest in the effect of human activity on the global environment, especially the effect of greenhouse gases and land-use change on the global climate, and models are being developed to study both global and local effects of global changes. This research involves the development and application of GRASP (Groundwater Recharge modelling Approach with a Scaling-up Procedure) intended as a component of UP (Upscaled physically based) large-scale hydrological model. GRASP comprises two modelling schemes: SM (Soil Moisture approach) and TF (Transfer Function approach), both based on the one-dimensional Richards' equation. TF is a transfer function model for inhomogeneous vertical flow in the unsaturated zone and gives the recharge response for a short pulse of infiltration at the ground surface or percolation from the root zone. TF is point-based and its parameters are physically-based, derived using the matric potential and unsaturated hydraulic conductivity functions. SM is a simple, computationally efficient, grid-based, two parameters scheme, which are derived based on TF's point-scale aggregated response. Since TF is linear, upscaled transfer functions can be derived through area-weighted summation of point scale transfer functions. Two applications of GRASP are shown, one using data for Little Washita catchment in the ARRB (USA) and another using data from ABRACOS experiment in Central Amazon (Brazil). Although completely validation of the GRASP model needs more data, as shown, results are quite encouraging.

Pimenteldasilva, L.

2002-12-01

213

Integrating hydrologic modeling and land use projections for evaluation of hydrologic response and regional water supply impacts in semi-arid environments  

Microsoft Academic Search

Semi-arid environments are generally more sensitive to urbanization than humid regions in terms of both hydrologic modifications\\u000a and water resources sustainability. The current study integrates hydrologic modeling and land use projections to predict long-term\\u000a impacts of urbanization on hydrologic behavior and water supply in semi-arid regions. The study focuses on the Upper Santa\\u000a Clara River basin in northern Los Angeles

Minxue HeTerri; Terri S. Hogue

214

Possibilities of modelling of local and global hydrological changes from high-resolution Global Hydrological Model in the absolute gravity observations - the case of Józefos?aw Observatory  

NASA Astrophysics Data System (ADS)

Geodynamical use of epoch gravimetric relative and absolute observations requires the elimination of one from the most significant effect related to local and global changes of hydrological conditions. It is understood that hydrological effect is associated with changes in groundwater levels and soil moisture around the gravimetric station. In Poland, the quasi - permanent observations of gravity changes by absolute method carried out since 2005 on gravity station located in the Astronomical - Geodetic Observatory in Józefos?aw. In the poster will be shortly described measurement strategy of absolute observations and different approaches to the elimination of the local and global effects associated with changes in hydrology. This paper will discuss the results of the analysis of tidal observations relevant to the development of absolute observations - seasonal changes in barometric correction factor and differences in the locally designated tidal corrections model. Analysis of the possibility of elimination the impact of global hydrological influence is based on the model GLDAS a spatial resolution of 0.25 degree independently on a local scale and global. Józefos?aw Observatory is equipped with additional sensors linked to the monitoring of local hydrological conditions. It gives a possibility to verify the quality of modeling of hydrological changes using global models in local and global scale.

Olszak, Tomasz; Barlik, Marcin; Pachuta, Andrzej; Próchniewicz, Dominik

2014-05-01

215

Satellite Remote Sensing and Hydrological Modeling for Flood Inundation Mapping in Lake Victoria Basin: Implications for Hydrologic Prediction in Ungauged Basins  

NASA Astrophysics Data System (ADS)

Floods are among the most catastrophic natural disasters around the globe impacting human lives and infrastructure. Implementation of a flood prediction system can potentially reduce these losses. Typically, the set up and calibration of a hydrologic model requires in situ observations (e.g. rain gauges and stream gauges). Satellite remote sensing data have emerged as viable alternatives or supplements to in situ observations due to their coverage over ungauged regions. The focus of this study is to utilize the best available satellite products and integrate them in a state-of-the-art hydrologic model to characterize the spatial extent of flooding and associated hazards over sparsely-gauged or ungauged basins. This study presents a methodology based entirely on satellite remote sensing data to calibrate a hydrologic model, simulate the spatial extent of flooding, and evaluate the probability of detecting inundated areas. A raster-based distributed hydrologic model, CREST, was implemented for the Nzoia basin, a sub-basin of Lake Victoria (Africa). MODIS- and ASTER-based flood inundation maps were retrieved over the region and used to benchmark the distributed hydrologic model simulations of streamflow and inundation areas. The analysis showed the applicability of integrating satellite data products as input for a distributed hydrological model as well as direct estimation of flood extent maps. The quantification of flooding spatial extent through orbital sensors can help to evaluate hydrologic models and hence potentially improve hydrologic prediction and flood management strategies in ungauged catchments.

Khan, S. I.; Hong, Y.; Wang, J.; Yilmaz, K. K.; Gourley, J. J.; Adler, R. F.; Brakenridge, G. R.; Policelli, F.; Habib, S.; Irwin, D.

2009-12-01

216

Parameterization of a hydrological model using remote sensing data  

NASA Astrophysics Data System (ADS)

The alteration of land cover by humans has multiple consequences on biological systems ranging from local to global scales. The United Nations have rated land use changes as one of the major issues for the coming centuries. In Northern Germany a significant land use change can be observed since 2004, i.e. the amendment of the Renewable Energies Act. Since then, an increasing number of biogas plants have been built resulting in an increased cultivation of so-called energy crops, especially in direct neighbourhood to these plants. Conversion of land is known to alter hydrological processes such as the exchange of energy and water. To investigate the effects of land use change on the water cycle in lowland river catchments in Northern Germany, we used a series of land cover data for the Upper Stoer, a sub-catchment of the river Elbe, as the input for a hydrological model. To derive the land cover data, we applied maximum-likelihood classifications of Landsat TM data for the years 2003 and 2010. The open source model suite SWAT (Soil Water Assessment Tool) was used to model the water cycle. SWAT has proven to be a useful tool for simulating the effect of watershed processes and management practices on water resources. A comparison of the modelled and observed discharge at the outlet of the catchment (gauge Willenscharen) showed good results (Nash Sutcliffe = 0.62). However, the land use change had no measurable effect on the discharge at the outlet due to the masking influence of high groundwater levels in the catchment. Therefore focusing on the discharge at the outlet is not a suitable approach in such cases. To represent the spatial characteristics of a catchment as realistically as possible, the catchment area must be spatially discretized. The configuration used primarily within SWAT is the sub-watershed discretization scheme. This results in a loss of spatial information, which is problematic for our intended applications. Therefore we developed an alternative model interface to manage input and output data based on grid cells. This enabled us to model the changes in evapotranspiration patterns in the catchment with changing land use more realistically and to calculate the water balance for each grid cell without losing its geographic reference. Therefore, the grid cells can interact with each other and exchange matter and energy, which was not possible using the sub-watershed approach. Therefore, the grid-cell interface enables the implementation of remote sensing data to provide a spatially distributed modelling.

Oppelt, N.; Rathjens, H.; Müller, T.-L.

2012-04-01

217

Hydrological application of the INCA model with varying spatial resolution and nitrogen dynamics in a northern river basin Hydrology and Earth System Sciences, 6(3), 339350 (2002) EGS  

E-print Network

Hydrological application of the INCA model with varying spatial resolution and nitrogen dynamics in a northern river basin 339 Hydrology and Earth System Sciences, 6(3), 339­350 (2002) © EGS Hydrological ), this paper focuses on calibration of the hydrological part of the model and nitrogen (N) dynamics

Boyer, Edmond

218

Calibration of a Hydrologic Model Considering Input Uncertainty in Assessing Climate Change Impact on Streamflow  

NASA Astrophysics Data System (ADS)

Studies on impact assessment and the corresponding uncertainties in hydrologic regime predictions is of paramount in developing water resources management plans under climate change scenarios,. The variability in hydrologic model parameters is one of the major sources of uncertainties associated with climate change impact on streamflow. Uncertainty in hydrologic model parameters may arise from the choice of model calibration technique, model calibration period, model structure and response variables. The recent studies show that consideration of uncertainties in input variables (precipitation, evapotranspiration etc.) during calibration of a hydrologic model has resulted in decrease in prediction uncertainty. The present study has examined the significance of input uncertainty in hydrologic model calibration for climate change impact studies. A physically distributed hydrologic model, Soil and Water Assessment Tool (SWAT), is calibrated considering uncertainties in (i) model parameters only, and (ii) both model parameters and precipitation input. The Markov chain Monte Carlo algorithm is used to estimate the posterior probability density function of hydrologic model parameters. The observed daily precipitation and streamflow data of the Canard River watershed of Essex region, Ontario, Canada are used as input and output variables, respectively, during calibration. The parameter sets of the 100 most skillful hydrologic model simulations obtained from each calibration technique are used for predicting streamflow by 2070s under climate change conditions. In each run, the climate predictions of the Canadian Regional Climate Model (CRCM) for SRES scenario A2 are used as input to the hydrologic model for streamflow prediction. The paper presents the results of uncertainty in seasonal and annual streamflow prediction. The outcome of the study is expected to contribute to the assessment of uncertainty in climate change impact studies and better management of available water resources.

Bolisetti, T.; Datta, A. R.; Balachandar, R.

2009-05-01

219

Significance of hydrological model choice and land use changes when doing climate change impact assessment  

NASA Astrophysics Data System (ADS)

Uncertainty in impact studies arises both from Global Climate Models (GCM), emission projections, statistical downscaling, Regional Climate Models (RCM), hydrological models and calibration techniques (Refsgaard et al. 2013). Some of these uncertainties have been evaluated several times in the literature; however few studies have investigated the effect of hydrological model choice on the assessment results (Boorman & Sefton 1997; Jiang et al. 2007; Bastola et al. 2011). These studies have found that model choice results in large differences, up to 70%, in the predicted discharge changes depending on the climate input. The objective of the study is to investigate the impact of climate change on hydrology of the Odense catchment, Denmark both in response to (a) different climate projections (GCM-RCM combinations); (b) different hydrological models and (c) different land use scenarios. This includes: 1. Separation of the climate model signal; the hydrological model signal and the land use signal 2. How do the different hydrological components react under different climate and land use conditions for the different models 3. What land use scenario seems to provide the best adaptation for the challenges of the different future climate change scenarios from a hydrological perspective? Four climate models from the ENSEMBLES project (Hewitt & Griggs 2004): ECHAM5 - HIRHAM5, ECHAM5 - RCA3, ARPEGE - RM5.1 and HadCM3 - HadRM3 are used, assessing the climate change impact in three periods: 1991-2010 (present), 2041-2060 (near future) and 2081-2100 (far future). The four climate models are used in combination with three hydrological models with different conceptual layout: NAM, SWAT and MIKE SHE. Bastola, S., C. Murphy and J. Sweeney (2011). "The role of hydrological modelling uncertainties in climate change impact assessments of Irish river catchments." Advances in Water Resources 34: 562-576. Boorman, D. B. and C. E. M. Sefton (1997). "Recognising the uncertainty in the quantification of the effects of climate change on hydrological response." Climate Change 35: 415-434. Hewitt, C. D. and D. J. Griggs (2004). "Ensembles-based predictions of climate changes and their impacts." Eos, Transactions American Geophysical Union 85: 1-566. Jiang, T., Y. D. Chen, C. Xu, X. Chen, X. Chen and V. P. Singh (2007). "Comparison of hydrological impacts of climate change simulated by six hydrological models in the Dongjiang Basin, South China." Journal of hydrology 336: 316-333. Refsgaard, J. C., K. Arnbjerg-Nielsen, M. Drews, K. Halsnæs, E. Jeppesen, H. Madsen, A. Markandya, J. E. Olesen, J. R. Porter and J. H. Christensen (2013). "The role of uncertainty in climate change adaptation strategies - A Danish water management example." Mitigation and Adaptation Strategies for Global Change 18: 337-359.

Bjørnholt Karlsson, Ida; Obel Sonnenborg, Torben; Refsgaard, Jens Christian; Høgh Jensen, Karsten

2014-05-01

220

Hydrologic Implications of Dynamical and Statistical Approaches to Downscaling Climate Model Outputs  

SciTech Connect

Six approaches for downscaling climate model outputs for use in hydrologic simulation were evaluated, with particular emphasis on each method's ability to produce precipitation and other variables used to drive a macroscale hydrology model applied at much higher spatial resolution than the climate model. Comparisons were made on the basis of a twenty-year retrospective (1975–1995) climate simulation produced by the NCAR-DOE Parallel Climate Model (PCM), and the implications of the comparison for a future (2040–2060) PCM climate scenario were also explored. The six approaches were made up of three relatively simple statistical downscaling methods – linear interpolation (LI), spatial disaggregation (SD), and bias-correction and spatial disaggregation (BCSD) – each applied to both PCM output directly (at T42 spatial resolution), and after dynamical downscaling via a Regional Climate Model (RCM – at ½-degree spatial resolution), for downscaling the climate model outputs to the ?-degree spatial resolution of the hydrological model. For the retrospective climate simulation, results were compared to an observed gridded climatology of temperature and precipitation, and gridded hydrologic variables resulting from forcing the hydrologic model with observations. The most significant findings are that the BCSD method was successful in reproducing the main features of the observed hydrometeorology from the retrospective climate simulation, when applied to both PCM and RCM outputs. Linear interpolation produced better results using RCM output than PCM output, but both methods (PCM-LI and RCM-LI) lead to unacceptably biased hydrologic simulations. Spatial disaggregation of the PCM output produced results similar to those achieved with the RCM interpolated output; nonetheless, neither PCM nor RCM output was useful for hydrologic simulation purposes without a bias-correction step. For the future climate scenario, only the BCSD-method (using PCM or RCM) was able to produce hydrologically plausible results. With the BCSD method, the RCM-derived hydrology was more sensitive to climate change than the PCM-derived hydrology.

Wood, Andrew W.; Leung, Lai R.; Sridhar, V.; Lettenmaier, D. P.

2004-01-01

221

Modeling the impact of hydrological changes on nitrate transport in the Mississippi River Basin from 1955 to 1994  

Microsoft Academic Search

The export of nitrate by the Mississippi River to the Gulf of Mexico has tripled since the 1950s primarily due to an increase in agricultural fertilizer application and hydrological changes. Here we have adapted two physically based models, the Integrated Biosphere Simulator (IBIS) terrestrial ecosystem model and the Hydrological Routing Algorithm (HYDRA) hydrological transport model, to simulate the nitrate export

Simon D. Donner; Michael T. Coe; John D. Lenters; Tracy E. Twine; Jonathan A. Foley

2002-01-01

222

Apply a hydrological model to estimate local temperature trends  

NASA Astrophysics Data System (ADS)

Continuous times series {f(x)} such as a depth of water is written f(x) = T(x)+P(x)+S(x)+C(x) in hydrological science where T(x),P(x),S(x) and C(x) are called the trend, periodic, stochastic and catastrophic components respectively. We simplify this model and apply it to the local temperature data such as given E. Halley (1693), the UK (1853-2010), Germany (1880-2010), Japan (1876-2010). We also apply the model to CO2 data. The model coefficients are evaluated by a symbolic computation by using a standard personal computer. The accuracy of obtained nonlinear curve is evaluated by the arithmetic mean of relative errors between the data and estimations. E. Halley estimated the temperature of Gresham College from 11/1692 to 11/1693. The simplified model shows that the temperature at the time rather cold compared with the recent of London. The UK and Germany data sets show that the maximum and minimum temperatures increased slowly from the 1890s to 1940s, increased rapidly from the 1940s to 1980s and have been decreasing since the 1980s with the exception of a few local stations. The trend of Japan is similar to these results.

Igarashi, Masao; Shinozawa, Tatsuya

2014-03-01

223

OBJTOP - A New Model to Simulate Hydrological Processes  

NASA Astrophysics Data System (ADS)

Object-Oriented Design (OOD) methods and the Objected-Oriented Programming (OOP) language-C++ were used to create a new version of TOPMODEL, a spatially explicit and topographically based watershed runoff model. The new model, referred to as OBJTOP, both a) realizes the benefits of the OOD and OOP compared with traditional procedural based programming, as well as b) allows for easy relaxation of four hydrological defaults in the traditional TOPMODEL scheme. The OOD and OOP benefits of OBJTOP include features of encapsulation, inheritance, reusability, and polymorphism. More pertinent to non-programmers, the OOD and OOP enable OBJTOP to efficiently simulate watersheds of any size and for any duration without redimensionalzing arrays and recompiling the source code. Further, OBJTOP provides model routines, and an interactive graphical user interface (GUI), that allows users to simulate 1) saturation excess or infiltration excess overland flow, 2) exponential or power law decay of hydraulic conductivity with depth, 3) soil topographic index or topographic index weighting of runoff likelihood, 4) multiple of single watershed simulation, and 5) with or without channel routing. This presentation will present the underlying OOD and OOP structure used to create OBJTOP and illustrate the model calibration advantages of easy relaxation of TOPMODEL assumptions.

Wang, J.; Endreny, T. A.

2002-05-01

224

Stable Isotope Tracers in Large Scale Hydrological Models  

NASA Astrophysics Data System (ADS)

Stable isotopes of oxygen and hydrogen (deuterium and oxygen-18) have been shown to be effective tracers for characterizing hydrological processes in small river basins. Their application in large river basins has lagged behind due to the lack of sufficient isotope data. Recent availability of isotope data from most US rivers and subsequent efforts by the International Atomic Energy Agency (IAEA) to collect comprehensive global information on isotope compositions of river runoff is changing this situation. These data sets offer new opportunities to utilize stable isotopes in studies of large river basins. Recent work carried out jointly by the Water Systems Analysis Group of the University of New Hampshire and the Isotope Hydrology Section of the IAEA applied isotope-enabled global water balance and transport models to assess the feasibility of using isotope data for improving water balance estimations at large scales. The model implemented simple mixing in the various storage pools (e.g. snow pack, soil moisture, groundwater, and river channel) and fractionation during evapotranspiration. Sensitivity tests show that spatial and temporal distributions of isotopes in precipitation and their mixing in the various storage pools are the most important factors affecting the isotopic composition of river discharge. The groundwater storage pool plays a key role in the seasonal dynamics of stable isotope composition of river discharge. Fractionation during phase changes appears to have a less pronounced impact. These findings are consistent with those in small scale catchments where ``old water'' and ``new water'' (i.e. pre-event water and storm runoff) can be easily separated by using isotopes. Model validation using available data from the US rivers showed remarkable performance considering the inconsistencies in the temporal sampling of precipitation and runoff isotope composition records. The good model performance suggests that seasonal variations of the isotopic composition of the precipitation and as a consequence the runoff follow a regular pattern that is less affected by inter-annual variations. The presentation will discuss the design and implementation of the isotope enabled water balance/transport model, its application and the potential of using global isotope information as (``soft'') calibration/validation data. Because of the sensitivity of runoff isotopic composition to groundwater storage pools, isotope data may offer new opportunities to assess the volumes of these storage terms and to evaluate their sustainability for human use.

Fekete, B. M.; Aggarwal, P.

2004-05-01

225

The TopoFlow Hydrologic Model: A New Community Project  

NASA Astrophysics Data System (ADS)

TopoFlow is a powerful, spatially-distributed hydrologic model with a user-friendly, wizard-style point-and-click interface. It is an open-source model that was designed to be easily modified and extended by a user community of hydrologists. Its main purpose is to model many different physical processes in a watershed with the goal of accurately predicting how various hydrologic variables will evolve in time in response to climatic forcings. The streamlined graphical interface makes it easy to perform multiple runs with different settings and different methods for parameterizing various physical processes; this makes it an excellent tool for research and teaching. Time evolutions for single pixels (such as hydrographs), collections of pixels, or entire grids (as animations) are all supported as output options. The currently supported physical processes are: Snowmelt (degree-day or energy balance method), Precipitation (uniform or varying in space/time), Evapotranspiration (Priestley-Taylor or energy balance), Infiltration (Green-Ampt coming soon), Channel/overland flow (Manning or law of wall) and Darcian, multi-layer subsurface flow. For each physical process, the user selects a "method" to be used to model that process from a droplist of options, and then specifies the input data that is required for that method and the output variables that are of interest. The ability to handle springs, sinks and canals was recently added. TopoFlow is designed so that users can use existing methods, share methods with others, or add their own methods and incorporate them into the graphical user interface. A method called "None" is always available to turn off any given physical process, and cleanly-written templates are provided to simplify the task of adding new methods. Input variables may be specified as a scalar (to be distributed uniformly), a time series, a spatial grid, or a grid seqence indexed by time. Many of the physical process methods used in TopoFlow are based on those in the ARHYTHM model, as documented by Zhang et el. (2000). ARHYTHM has been validated with data for many Arctic watersheds. TopoFlow is a work in progress and we are very interested in getting other groups involved as users, testers, and developers.

Peckham, S. D.

2004-05-01

226

The application of remote sensing to the development and formulation of hydrologic planning models: Executive summary  

NASA Technical Reports Server (NTRS)

Methods for the reduction of remotely sensed data and its application in hydrologic land use assessment, surface water inventory, and soil property studies are presented. LANDSAT data is used to provide quantitative parameters and coefficients to construct watershed transfer functions for a hydrologic planning model aimed at estimating peak outflow from rainfall inputs.

Castruccio, P. A.; Loats, H. L., Jr.; Fowler, T. R.

1977-01-01

227

Operational Hydrologic Simulation Modeling at the Natural Resources Conservation Service's National Water and Climate Center  

Microsoft Academic Search

This paper describes the current status and anticipated near-term future directions of the U.S. Department of Agriculture's Natural Resources Conservation Service's (NRCS) National Water and Climate Center with respect to the use of hydrologic simulation models. It begins with a description of the water supply forecasting operations, and continues with a review of past attempts to adopt operational hydrologic simulation

Thomas Pagano; Tom Perkins; Jennifer Erxleben

228

Development and application of a simple hydrologic model simulation for a Brazilian headwater basin  

Microsoft Academic Search

Physically based hydrologic models for watersheds are important tools to support water resources management and predict hydrologic impacts produced by land-use change. Grande River Basin is located in southern Minas Gerais State, and the Grande River is the main tributary of Basin which has 2080 km2 draining into the Camargos Hydropower Plant Reservoir (CEMIG — “Minas Gerais State Energy Company”). The

C. R. Mello; M. R. Viola; L. D Norton; A. M. Silva; F. A. Weimar

2008-01-01

229

Land Surface Hydrology Parameterization for Atmospheric General Circulation models Including Subgrid Scale Spatial Variability  

Microsoft Academic Search

Parameterizations are developed for the representation of subgrid hydrologic processes in atmospheric general circulation models. Reasonable a priori probability density functions of the spatial variability of soil moisture and of precipitation are introduced. These are used in conjunction with the deterministic equations describing basic soil moisture physics to derive expressions for the hydrologic processes that include subgrid scale variation in

D. Entekhabi; P. S. Eagleson

1989-01-01

230

Catchment modeling and model transferability in upper Blue Nile Basin, Lake Tana, Ethiopia  

Microsoft Academic Search

Understanding spatial and temporal distribution of water resources has an important role for water resource management. To understand water balance dynamics and runoff generation mechanisms at the Gilgel Abay catchment (a major tributary into lake Tana, source of Blue Nile, Ethiopia) and to evaluate model transferability, catchment modeling was conducted using the conceptual hydrological model HBV. The catchment of the

A. S. Gragne; S. Uhlenbrook; Y. Mohammed; S. Kebede

2008-01-01

231

Niger River Basin - Hydrological Modeling: Inter-changeability of parameters between models versions  

NASA Astrophysics Data System (ADS)

An enhanced hydrological framework from the existing conceptual model GR2M leads to significant results in inter-changing the models parameters, using the parameters obtained during the calibration process of a first model version in the validation process of a second model version. A two parameters and three input variables' conceptual framework called SimulHyd is used to simulate the runoff of sixteen watersheds on the Niger River and its tributaries, over eighteen years to forty six years. The first parameter controls the three model input variables and the second controls its output runoff information. Between either a lumped version and a semi-distributed version or the GR2M model and SimulHyd model, a set of three significant models parameters inter-changeability are detected: SimulHyd is better in validation process after 1970 using the calibrated parameters from GR2M before 1970, in forward modeling; GR2M is better in validation process before 1970 using the calibrated parameters from SimulHyd after 1970; and in some cases the models are more efficient in validation than in calibration. The combination both of two hydrological models drifting one of the other and of two concepts of modeling are used to demonstrate a success in the synergy of four models versions to simulate more accurately the behaviors of hydrological systems. This particularity (of these models version), responding positively in models parameters importing and exporting between different models versions, can be explored in the context of the assessment of climate change impact on water resources.INTER-CHANGED PARAMETERS NON-DISTRIBUTED MODELING VS SEMI-DISTRIBUTED MODELING SimulHyd (Simulation of hydrological Systems)N-D : Non-Distributed modelingS-D : Semi-Distributed modeling

KONE, S.

2013-12-01

232

PREDICTIVE UNCERTAINTY IN HYDROLOGIC AND WATER QUALITY MODELING: APPROACHES, APPLICATION TO ENVIRONMENTAL MANAGEMENT, AND FUTURE CHALLENGES  

EPA Science Inventory

Extant process-based hydrologic and water quality models are indispensable to water resources planning and environmental management. However, models are only approximations of real systems and often calibrated with incomplete and uncertain data. Reliable estimates, or perhaps f...

233

A comparison of alternative multiobjective calibration strategies for hydrological modeling  

NASA Astrophysics Data System (ADS)

A conceptual hydrological model structure contains several parameters that have to be estimated through matching observed and modeled watershed behavior in a calibration process. The requirement that a model simulation matches different aspects of system response at the same time has led the calibration problem toward a multiobjective approach. In this work we compare two multiobjective calibration approaches, each of which represents a different calibration philosophy. The first calibration approach is based on the concept of Pareto optimality and consists of calibrating all parameters with respect to a common set of objectives in one calibration stage. This approach results in a set of Pareto-optimal solutions representing the trade-offs between the selected calibration objectives. The second is a stepped calibration approach (SCA), which implies a stepwise calibration of sets of parameters that are associated with specific aspects of the system response. This approach replicates the steps followed by a hydrologist in manual calibration and develops a single solution. The comparison is performed considering the same set of objectives for the two approaches and two model structures of a different level of complexity. The difference in the two approaches, their reciprocal utility, and the practical implications involved in their application are analyzed and discussed using the Hesperange catchment case, an experimental basin in the Alzette River basin in Luxembourg. We show that the two approaches are not necessarily conflicting but can be complementary. The first approach provides useful information about the deficiencies of a model structure and therefore helps the model development, while the second attempts at determining a solution that is consistent with the data available. We also show that with increasing model complexity it becomes possible to reproduce the observations more accurately. As a result, the solutions for the different calibration objectives become less distinguishable from each other, indicating that calibration results become less dependent on the objective functions used when the model is a better representation of reality and has a higher potential to reproduce the observations.

Fenicia, Fabrizio; Savenije, Hubert H. G.; Matgen, Patrick; Pfister, Laurent

2007-03-01

234

Accesible hydrological monitoring for better decision making and modelling: a regional initiative in the Andes  

NASA Astrophysics Data System (ADS)

The goal of the Hydrological Monitoring of Andean Ecosystems Initiative is to improve the conservation and management of High-Andean ecosystems by providing information on the hydrological response of these ecosystems and how different land-uses affect their water yield and regulation capacity. The initiative fills a gap left by widespread hydrological modeling exercises that suffer from lack of data, and by glacier monitoring under climate change. The initiative proposes a hydrological monitoring system involving precipitation, discharge and land cover monitoring in paired catchments. The methodology is accessible for non-specialist organizations, and allows for generation of evidence of land use impact on hydrology on the short term (i.e. a few years). Nevertheless, long term monitoring is pursued with the aim of identifying trends in hydrological response (as opposed to trends in climate) under global change. In this way it supports decision making on the preservation of the hydrological services of the catchment. The initiative aims at a high number of paired catchment sites along the Andes, in order to draw regional conclusions and capture variability, and is connected to more detailed hydrological research sites of several Andean universities. We present preliminary results of a dozen of sites from Venezuela to Bolivia, summarized in hydrological performance indicators that were agreed upon among hydrologists, local stakeholders, and water authorities. The success factors, as well as limitations, of the network are discussed.

De Bievre, B.; Célleri, R.; Crespo, P.; Ochoa, B.; Buytaert, W.; Tobón, C.; Villacís, M.; Villazon, M. F.; Llerena, C.; Rodriguez, M.; Viñas, P.

2013-05-01

235

Regional scale hydrology with a new land surface processes model  

NASA Technical Reports Server (NTRS)

Through the CaPE Hydrometeorology Project, we have developed an understanding of some of the unique data quality issues involved in assimilating data of disparate types for regional-scale hydrologic modeling within a GIS framework. Among others, the issues addressed here include the development of adequate validation of the surface water budget, implementation of the STATSGO soil data set, and implementation of a remote sensing-derived landcover data set to account for surface heterogeneity. A model of land surface processes has been developed and used in studies of the sensitivity of surface fluxes and runoff to soil and landcover characterization. Results of these experiments have raised many questions about how to treat the scale-dependence of land surface-atmosphere interactions on spatial and temporal variability. In light of these questions, additional modifications are being considered for the Marshall Land Surface Processes Model. It is anticipated that these techniques can be tested and applied in conjunction with GCIP activities over regional scales.

Laymon, Charles; Crosson, William

1995-01-01

236

Modeling low impact development potential with hydrological response units.  

PubMed

Evaluations of benefits of implementing low impact development (LID) stormwater management techniques can extend up to a watershed scale. This presents a challenge for representing them in watershed models, since they are typically orders of magnitude smaller in size. This paper presents an approach that is focused on trying to evaluate the benefits of implementing LIDs on a lot level. The methodology uses the concept of urban hydrological response Unit and results in developing and applying performance curves that are a function of lot properties to estimate the potential benefit of large-scale LID implementation. Lot properties are determined using a municipal geographic information system database and processed to determine groups of lots with similar properties. A representative lot from each group is modeled over a typical rainfall year using USEPA Stormwater Management Model to develop performance functions that relate the lot properties and the change in annual runoff volume and corresponding phosphorus loading with different LIDs implemented. The results of applying performance functions on all urban areas provide the potential locations, benefit and cost of implementation of all LID techniques, guiding future decisions for LID implementation by watershed area municipalities. PMID:24334886

Eric, Marija; Fan, Celia; Joksimovic, Darko; Li, James Y

2013-01-01

237

Hydrological improvements for nutrient and pollutant emission modeling in large scale catchments  

NASA Astrophysics Data System (ADS)

An estimation of emissions and loads of nutrients and pollutants into European water bodies with as much accuracy as possible depends largely on the knowledge about the spatially and temporally distributed hydrological runoff patterns. An improved hydrological water balance model for the pollutant emission model MoRE (Modeling of Regionalized Emissions) (IWG, 2011) has been introduced, that can form an adequate basis to simulate discharge in a hydrologically differentiated, land-use based way to subsequently provide the required distributed discharge components. First of all the hydrological model had to comply both with requirements of space and time in order to calculate sufficiently precise the water balance on the catchment scale spatially distributed in sub-catchments and with a higher temporal resolution. Aiming to reproduce seasonal dynamics and the characteristic hydrological regimes of river catchments a daily (instead of a yearly) time increment was applied allowing for a more process oriented simulation of discharge dynamics, volume and therefore water balance. The enhancement of the hydrological model became also necessary to potentially account for the hydrological functioning of catchments in regard to scenarios of e.g. a changing climate or alterations of land use. As a deterministic, partly physically based, conceptual hydrological watershed and water balance model the Precipitation Runoff Modeling System (PRMS) (USGS, 2009) was selected to improve the hydrological input for MoRE. In PRMS the spatial discretization is implemented with sub-catchments and so called hydrologic response units (HRUs) which are the hydrotropic, distributed, finite modeling entities each having a homogeneous runoff reaction due to hydro-meteorological events. Spatial structures and heterogeneities in sub-catchments e.g. urbanity, land use and soil types were identified to derive hydrological similarities and classify in different urban and rural HRUs. In this way the hydrological system is simulated spatially differentiated and emissions from urban and rural areas into river courses can be detected separately. In the Ruhr catchment (4.485 km2) as a right tributary of the Rhine located in the lower mountain range of North Rhine-Westphalia in Germany for the validation period 2002-2006 the hydrological model showed first satisfying results. The feasibility study in the Ruhr shows the suitability of the approach and illustrates the potentials for further developments in terms of an implementation throughout the German and contiguous watersheds. IWG, Karlsruhe Institute of Technology (KIT). 2011. http://isww.iwg.kit.edu/MoRE.php. [Online] Institute for Water and River Basin Management, Department of Aquatic Environmental Engineering, October 2011. USGS, U.S. Geological Survey. 2009. PRMS-2009, the Precipitation-Runoff Modeling System. Denver, Colorado : s.n., 2009. Bd. U.S. Geologic Survey Open File Report.

Höllering, S.; Ihringer, J.

2012-04-01

238

Data-intensive hydrologic modeling: A Cloud strategy for integrating PIHM, GIS, and Web-Services  

Microsoft Academic Search

The Penn State Integrated Hydrologic Model (PIHM) is an open-sourced fully coupled multi-process hydrologic model. This research is developing PIHM in a Cloud environment. We have transformed the model development process into a web-service workflow to simplify the complexity of pre-processing large data sets and model visualization. Users are now able to automatically generate PIHM input files from national databases

L. N. Leonard; C. Duffy; G. Bhatt

2010-01-01

239

Hydrologic modeling using elevationally adjusted NARR and NARCCAP regional climate-model simulations: Tucannon River, Washington  

NASA Astrophysics Data System (ADS)

An emerging approach to downscaling the projections from General Circulation Models (GCMs) to scales relevant for basin hydrology is to use output of GCMs to force higher-resolution Regional Climate Models (RCMs). With spatial resolution often in the tens of kilometers, however, even RCM output will likely fail to resolve local topography that may be climatically significant in high-relief basins. Here we develop and apply an approach for downscaling RCM output using local topographic lapse rates (empirically-estimated spatially and seasonally variable changes in climate variables with elevation). We calculate monthly local topographic lapse rates from the 800-m Parameter-elevation Regressions on Independent Slopes Model (PRISM) dataset, which is based on regressions of observed climate against topographic variables. We then use these lapse rates to elevationally correct two sources of regional climate-model output: (1) the North American Regional Reanalysis (NARR), a retrospective dataset produced from a regional forecasting model constrained by observations, and (2) a range of baseline climate scenarios from the North American Regional Climate Change Assessment Program (NARCCAP), which is produced by a series of RCMs driven by GCMs. By running a calibrated and validated hydrologic model, the Soil and Water Assessment Tool (SWAT), using observed station data and elevationally-adjusted NARR and NARCCAP output, we are able to estimate the sensitivity of hydrologic modeling to the source of the input climate data. Topographic correction of regional climate-model data is a promising method for modeling the hydrology of mountainous basins for which no weather station datasets are available or for simulating hydrology under past or future climates.

Praskievicz, Sarah; Bartlein, Patrick

2014-09-01

240

Phosphatidylcholine alteration identified using MALDI imaging MS in HBV-infected mouse livers and virus-mediated regeneration defects.  

PubMed

In this study, we investigated whether hepatitis B virus (HBV) causes the alteration of lipid metabolism and composition during acute infection and liver regeneration in a mouse model. The liver controls lipid biogenesis and bile acid homeostasis. Infection of HBV causes various liver diseases and impairs liver regeneration. As there are very few reports available in the literature on lipid alterations by HBV infection or HBV-mediated liver injury, we have analyzed phospholipids that have important roles in liver regeneration by using matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS) in the livers of HBV model mice. As a result, we identified different phosphatidylcholines (PCs) showing significant changes in their composition as well as cationized ion adduct formation in HBV-infected mouse livers which are associated with virus-mediated regeneration defects. To find the factor of altered PCs, the expression kinetics of enzymes was also examined that regulate PC biosynthesis during liver regeneration. It is noteworthy that the expression of choline-phosphate cytidylyltransferase A (PCYT1A) was significantly delayed in wild type HBV-expressing livers. Moreover, the amount of hepatic total PC was also significantly decreased in wt HBV-expressing mice. These results suggest that infection of HBV alters the composition of PCs which may involve in HBV-mediated regeneration defects and liver disease. PMID:25101682

Park, Eun-Sook; Lee, Jeong Hwa; Hong, Ji Hye; Park, Yong Kwang; Lee, Joon Won; Lee, Won-Jae; Lee, Jae Won; Kim, Kwang Pyo; Kim, Kyun-Hwan

2014-01-01

241

Phosphatidylcholine Alteration Identified Using MALDI Imaging MS in HBV-Infected Mouse Livers and Virus-Mediated Regeneration Defects  

PubMed Central

In this study, we investigated whether hepatitis B virus (HBV) causes the alteration of lipid metabolism and composition during acute infection and liver regeneration in a mouse model. The liver controls lipid biogenesis and bile acid homeostasis. Infection of HBV causes various liver diseases and impairs liver regeneration. As there are very few reports available in the literature on lipid alterations by HBV infection or HBV-mediated liver injury, we have analyzed phospholipids that have important roles in liver regeneration by using matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS) in the livers of HBV model mice. As a result, we identified different phosphatidylcholines (PCs) showing significant changes in their composition as well as cationized ion adduct formation in HBV-infected mouse livers which are associated with virus-mediated regeneration defects. To find the factor of altered PCs, the expression kinetics of enzymes was also examined that regulate PC biosynthesis during liver regeneration. It is noteworthy that the expression of choline-phosphate cytidylyltransferase A (PCYT1A) was significantly delayed in wild type HBV-expressing livers. Moreover, the amount of hepatic total PC was also significantly decreased in wt HBV-expressing mice. These results suggest that infection of HBV alters the composition of PCs which may involve in HBV-mediated regeneration defects and liver disease. PMID:25101682

Park, Eun-Sook; Lee, Jeong Hwa; Hong, Ji Hye; Park, Yong Kwang; Lee, Joon Won; Lee, Won-Jae; Lee, Jae Won; Kim, Kwang Pyo; Kim, Kyun-Hwan

2014-01-01

242

Statistical procedures for evaluating daily and monthly hydrologic model predictions  

USGS Publications Warehouse

The overall study objective was to evaluate the applicability of different qualitative and quantitative methods for comparing daily and monthly SWAT computer model hydrologic streamflow predictions to observed data, and to recommend statistical methods for use in future model evaluations. Statistical methods were tested using daily streamflows and monthly equivalent runoff depths. The statistical techniques included linear regression, Nash-Sutcliffe efficiency, nonparametric tests, t-test, objective functions, autocorrelation, and cross-correlation. None of the methods specifically applied to the non-normal distribution and dependence between data points for the daily predicted and observed data. Of the tested methods, median objective functions, sign test, autocorrelation, and cross-correlation were most applicable for the daily data. The robust coefficient of determination (CD*) and robust modeling efficiency (EF*) objective functions were the preferred methods for daily model results due to the ease of comparing these values with a fixed ideal reference value of one. Predicted and observed monthly totals were more normally distributed, and there was less dependence between individual monthly totals than was observed for the corresponding predicted and observed daily values. More statistical methods were available for comparing SWAT model-predicted and observed monthly totals. The 1995 monthly SWAT model predictions and observed data had a regression Rr2 of 0.70, a Nash-Sutcliffe efficiency of 0.41, and the t-test failed to reject the equal data means hypothesis. The Nash-Sutcliffe coefficient and the R r2 coefficient were the preferred methods for monthly results due to the ability to compare these coefficients to a set ideal value of one.

Coffey, M.E.; Workman, S.R.; Taraba, J.L.; Fogle, A.W.

2004-01-01

243

Improving student comprehension of the interconnectivity of the hydrologic cycle with a novel 'hydrology toolbox', integrated watershed model, and companion textbook  

NASA Astrophysics Data System (ADS)

Concepts in introductory hydrology courses are often taught in the context of process-based modeling that ultimately is integrated into a watershed model. In an effort to reduce the learning curve associated with applying hydrologic concepts to real-world applications, we developed and incorporated a 'hydrology toolbox' that complements a new, companion textbook into introductory undergraduate hydrology courses. The hydrology toolbox contains the basic building blocks (functions coded in MATLAB) for an integrated spatially-distributed watershed model that makes hydrologic topics (e.g. precipitation, snow, radiation, evaporation, unsaturated flow, infiltration, groundwater, and runoff) more user-friendly and accessible for students. The toolbox functions can be used in a modular format so that students can study individual hydrologic processes and become familiar with the hydrology toolbox. This approach allows such courses to emphasize understanding and application of hydrologic concepts rather than computer coding or programming. While topics in introductory hydrology courses are often introduced and taught independently or semi-independently, they are inherently interconnected. These toolbox functions are therefore linked together at the end of the course to reinforce a holistic understanding of how these hydrologic processes are measured, interconnected, and modeled. They are integrated into a spatially-distributed watershed model or numerical laboratory where students can explore a range of topics such as rainfall-runoff modeling, urbanization, deforestation, watershed response to changes in parameters or forcings, etc. Model output can readily be visualized and analyzed by students to understand watershed response in a real river basin or a simple 'toy' basin. These tools complement the textbook, each of which has been well received by students in multiple hydrology courses with various disciplinary backgrounds. The same governing equations that students have studied in the textbook and used in the toolbox have been encapsulated in the watershed model. Therefore, the combination of the hydrology toolbox, integrated watershed model, and textbook tends to eliminate the potential disconnect between process-based modeling and an 'off-the-shelf' watershed model.

Huning, L. S.; Margulis, S. A.

2013-12-01

244

Improving process representation in conceptual hydrological model calibration using climate simulations  

NASA Astrophysics Data System (ADS)

sets of calibrated model parameters can yield divergent hydrological simulations which in turn can lead to different operational decisions or scientific conclusions. In order to obtain reliable hydrological results, proper calibration is therefore fundamental. This article proposes a new calibration approach for conceptual hydrological models based on the paradigm that hydrological process representation, along with the reproduction of observed streamflows, need to be taken into account when assessing the performance of a hydrological model. Several studies have shown that complementary data can be used to improve hydrological process representation and make hydrological modeling more robust. In the current study, the process of interest is actual evapotranspiration (AET). In order to obtain a more realistic representation of AET, meteorological variables and the AET mean annual cycle simulated by a regional climate model (RCM) driven by reanalysis are used to impose constraints during the optimization procedure. This calibration strategy is compared to a second strategy which relies on AET derived from reference data and to the classical approach based solely on the reproduction of observed discharges. The different methodologies are applied to calibrate the lumped conceptual model HSAMI, used operationally at Hydro-Québec, for six Canadian snow-dominated basins with various hydrometeorological and physiographical characteristics.

Minville, Marie; Cartier, Dominique; Guay, Catherine; Leclaire, Louis-Alexandre; Audet, Charles; Le Digabel, Sébastien; Merleau, James

2014-06-01

245

HBV and the immune response.  

PubMed

Hepatitis B virus (HBV) infection acquired in adult life is generally self-limited while chronic persistence of the virus is the prevalent outcome when infection is acquired perinatally. Both control of infection and liver cell injury are strictly dependent upon protective immune responses, because hepatocyte damage is the price that the host must pay to get rid of intracellular virus. Resolution of acute hepatitis B is associated with functionally efficient, multispecific antiviral T-cell responses which are preceded by a poor induction of intracellular innate responses at the early stages of infection. Persistent control of infection is provided by long-lasting protective memory, which is probably sustained by continuous stimulation of the immune system by trace amounts of virus which are never totally eliminated, persisting in an occult episomic form in the nucleus of liver cells even after recovery from acute infection. Chronic virus persistence is instead characterized by a lack of protective T-cell memory maturation and by an exhaustion of HBV-specific T-cell responses. Persistent exposure of T cells to high antigen loads is a key determinant of functional T-cell impairment but also other mechanisms can contribute to T-cell inhibition, including the tolerogenic effect of the liver environment. The degree of T-cell impairment is variable and its severity is related to the level of virus replication and antigen load. The antiviral T-cell function is more efficient in patients who can control infection either partially, such as inactive HBsAg carriers with low levels of virus replication, or completely, such as patients who achieve HBsAg loss either spontaneously or after antiviral therapy. Thus, understanding the features of the immune responses associated with control of infection is needed for the successful design of novel immune modulatory therapies based on the reconstitution of efficient antiviral responses in chronic HBV patients. PMID:25529097

Ferrari, Carlo

2015-01-01

246

An Open Source modular platform for hydrological model implementation  

NASA Astrophysics Data System (ADS)

An implementation framework for setup and evaluation of spatio-temporal models is developed, forming a highly modularized distributed model system. The ENKI framework allows building space-time models for hydrological or other environmental purposes, from a suite of separately compiled subroutine modules. The approach makes it easy for students, researchers and other model developers to implement, exchange, and test single routines in a fixed framework. The open-source license and modular design of ENKI will also facilitate rapid dissemination of new methods to institutions engaged in operational hydropower forecasting or other water resource management. Written in C++, ENKI uses a plug-in structure to build a complete model from separately compiled subroutine implementations. These modules contain very little code apart from the core process simulation, and are compiled as dynamic-link libraries (dll). A narrow interface allows the main executable to recognise the number and type of the different variables in each routine. The framework then exposes these variables to the user within the proper context, ensuring that time series exist for input variables, initialisation for states, GIS data sets for static map data, manually or automatically calibrated values for parameters etc. ENKI is designed to meet three different levels of involvement in model construction: • Model application: Running and evaluating a given model. Regional calibration against arbitrary data using a rich suite of objective functions, including likelihood and Bayesian estimation. Uncertainty analysis directed towards input or parameter uncertainty. o Need not: Know the model's composition of subroutines, or the internal variables in the model, or the creation of method modules. • Model analysis: Link together different process methods, including parallel setup of alternative methods for solving the same task. Investigate the effect of different spatial discretization schemes. o Need not: Write or compile computer code, handle file IO for each modules, • Routine implementation and testing. Implementation of new process-simulating methods/equations, specialised objective functions or quality control routines, testing of these in an existing framework. o Need not: Implement user or model interface for the new routine, IO handling, administration of model setup and run, calibration and validation routines etc. From being developed for Norway's largest hydropower producer Statkraft, ENKI is now being turned into an Open Source project. At the time of writing, the licence and the project administration is not established. Also, it remains to port the application to other compilers and computer platforms. However, we hope that ENKI will prove useful for both academic and operational users.

Kolberg, Sjur; Bruland, Oddbjørn

2010-05-01

247

Modelling of green roofs' hydrologic performance using EPA's SWMM.  

PubMed

Green roofs significantly affect the increase in water retention and thus the management of rain water in urban areas. In Poland, as in many other European countries, excess rainwater resulting from snowmelt and heavy rainfall contributes to the development of local flooding in urban areas. Opportunities to reduce surface runoff and reduce flood risks are among the reasons why green roofs are more likely to be used also in this country. However, there are relatively few data on their in situ performance. In this study the storm water performance was simulated for the green roofs experimental plots using the Storm Water Management Model (SWMM) with Low Impact Development (LID) Controls module (version 5.0.022). The model consists of many parameters for a particular layer of green roofs but simulation results were unsatisfactory considering the hydrologic response of the green roofs. For the majority of the tested rain events, the Nash coefficient had negative values. It indicates a weak fit between observed and measured flow-rates. Therefore complexity of the LID module does not affect the increase of its accuracy. Further research at a technical scale is needed to determine the role of the green roof slope, vegetation cover and drying process during the inter-event periods. PMID:23823537

Burszta-Adamiak, E; Mrowiec, M

2013-01-01

248

The Impact of Microwave-Derived Surface Soil Moisture on Watershed Hydrological Modeling  

NASA Technical Reports Server (NTRS)

The usefulness of incorporating microwave-derived soil moisture information in a semi-distributed hydrological model was demonstrated for the Washita '92 experiment in the Little Washita River watershed in Oklahoma. Initializing the hydrological model with surface soil moisture fields from the ESTAR airborne L-band microwave radiometer on a single wet day at the start of the study period produced more accurate model predictions of soil moisture than a standard hydrological initialization with streamflow data over an eight-day soil moisture drydown.

ONeill, P. E.; Hsu, A. Y.; Jackson, T. J.; Wood, E. F.; Zion, M.

1997-01-01

249

Development of the forSIM model to quantify positive and negative hydrological impacts of tropical reforestation  

E-print Network

reforestation Nick A. Chappell a,*, Wlodek Tych a , Mike Bonell b a Lancaster Environment Centre, Lancaster Abstract Existing approaches to modelling the impacts of reforestation on tropical hydrology only simulate, illustrates quantifiable interrelationships between reforestation-related hydrological changes

Chappell, Nick A

250

SWAT hydrologic model parameter uncertainty and its implications for hydroclimatic projections in snowmelt-dependent watersheds  

NASA Astrophysics Data System (ADS)

The effects of climate change on water resources have been studied extensively throughout the world through the use of hydrologic models coupled with General Circulation Model (GCM) output or climate sensitivity scenarios. This paper examines the effects of hydrologic model parameterization uncertainty or equifinality, where multiple unique hydrologic model parameter sets can result in adequate calibration metrics, on hydrologic projections from downscaled GCMs for three snowmelt-dependent watersheds (upper reaches of the Clearwater, Gunnison, and Sacramento River watersheds) in the western United States. The hydrologic model used in this study is the Soil and Water Assessment Tool (SWAT) and is calibrated for discharge at the watershed outlet in each watershed. Despite achieving similar calibration metrics, a majority of hydrologic projections of average annual streamflow during the 2080s were statistically different, with differences in magnitude and direction (increase or decrease) compared to historical annual streamflows. At the average monthly time-scale, a majority of the hydrologic projections varied in peak streamflow timing, peak streamflow magnitude, summer streamflows, as well as overall increases or decreases compared to the historical monthly streamflows. Snowmelt projections from the SWAT model also widely varied, both in depth and snowmelt peak timing, for all watersheds. Since a large portion of the runoff-producing regions in the western United States is snowmelt-dependent, this has large implications for the prediction of the amount and timing of streamflow in the coming century. This paper shows that hydrologic model parameterizations that give similar adequate calibration metrics can lead to statistically significant differences in hydrologic projections under climate change. Therefore, researchers and water resource managers should account for this uncertainty by assembling ensemble projections from both multiple parameter sets and GCMs.

Ficklin, Darren L.; Barnhart, Bradley L.

2014-11-01

251

Review of soil water models with respect to savanna hydrology   

E-print Network

Effective management leading towards sustainable rangeland production in arid and semi-arid regions will stem from effective soil water management and comprehension of the hydrological properties of the soil in relation to pastoralism. However...

Derry, Julian F; Russell, Graham; Liedloff, Adam C

2006-07-21

252

Development and test of a spatially distributed hydrological\\/water quality model for mesoscale watersheds  

Microsoft Academic Search

The new watershed model SWIM was developed in order to provide a comprehensive GIS-based tool for hydrological and water quality modelling in mesoscale watersheds (from 100 to 10?000 km2), which can be parametrized using regionally available information. SWIM is based on two previously developed tools—SWAT and MATSALU. The model integrates hydrology, vegetation, erosion and nitrogen dynamics at the watershed scale.

Valentina Krysanova; Dirk-Ingmar Müller-Wohlfeil; Alfred Becker

1998-01-01

253

WATERSHED-SCALE HYDROLOGIC AND NONPOINT-SOURCE POLLUTION MODELS: REVIEW OF MATHEMATICAL BASES  

Microsoft Academic Search

A clear understanding of a model is important for its appropriate use. In this article, eleven watershed scale hydrologic and nonpoint-source pollution models are reviewed: AGNPS, AnnAGNPS, ANSWERS, ANSWERS-Continuous, CASC2D, DWSM, HSPF, KINEROS, MIKE SHE, PRMS, and SWAT. AnnAGNPS, ANSWERS-Continuous, HSPF, and SWAT are continuous simulation models useful for analyzing long-term effects of hydrological changes and watershed management practices, especially

D. K. Borah; M. Bera

254

Application of remote sensing to hydrology. [for the formulation of watershed behavior models  

NASA Technical Reports Server (NTRS)

Streamflow forecasting and hydrologic modelling are considered in a feasibility assessment of using the data produced by remote observation from space and/or aircraft to reduce the time and expense normally involved in achieving the ability to predict the hydrological behavior of an ungaged watershed. Existing watershed models are described, and both stochastic and parametric techniques are discussed towards the selection of a suitable simulation model. Technical progress and applications are reported and recommendations are made for additional research.

Ambaruch, R.; Simmons, J. W.

1973-01-01

255

On the Hydrologic Adjustment of Climate-Model Projections: The Potential Pitfall of Potential Evapotranspiration  

USGS Publications Warehouse

Hydrologic models often are applied to adjust projections of hydroclimatic change that come from climate models. Such adjustment includes climate-bias correction, spatial refinement ("downscaling"), and consideration of the roles of hydrologic processes that were neglected in the climate model. Described herein is a quantitative analysis of the effects of hydrologic adjustment on the projections of runoff change associated with projected twenty-first-century climate change. In a case study including three climate models and 10 river basins in the contiguous United States, the authors find that relative (i.e., fractional or percentage) runoff change computed with hydrologic adjustment more often than not was less positive (or, equivalently, more negative) than what was projected by the climate models. The dominant contributor to this decrease in runoff was a ubiquitous change in runoff (median -11%) caused by the hydrologic model’s apparent amplification of the climate-model-implied growth in potential evapotranspiration. Analysis suggests that the hydrologic model, on the basis of the empirical, temperature-based modified Jensen–Haise formula, calculates a change in potential evapotranspiration that is typically 3 times the change implied by the climate models, which explicitly track surface energy budgets. In comparison with the amplification of potential evapotranspiration, central tendencies of other contributions from hydrologic adjustment (spatial refinement, climate-bias adjustment, and process refinement) were relatively small. The authors’ findings highlight the need for caution when projecting changes in potential evapotranspiration for use in hydrologic models or drought indices to evaluate climate-change impacts on water.

Milly, Paul C.; Dunne, Krista A.

2011-01-01

256

Modeling and monitoring the hydrological effects of the Sand Engine.  

NASA Astrophysics Data System (ADS)

Since 1887, Dunea Water Company produces high quality drinking water using the dune area at Monster (Province of South Holland, the Netherlands). Annually, 8 billion liters of water is produced here using artificial recharge and recovery with shallow wells and infiltration lakes. The dunes are an important step in producing drinking water serving as an underground buffer, leveling fluctuating in temperature and quality and removing bacteria and viruses from the infiltrated water in a natural way. Since space is limited in the Netherlands, the drinking water production of Dunea is closely matched with surrounding land uses and natural constraints. This prevents groundwater nuisance, upconing and intrusion of salt water and, in this case, movement of a nearby groundwater pollution. This is especially true in the Monster area where the dunes are fairly low and small; the coast is less than 350 meters from the recovery wells. The coast of Monster was identified as a weak link in the coastal defense of The Netherlands. Because of this, two coastal defense projects were carried out between 2009 and 2011. The first project involved creating an extra dune ridge in front of existing dunes which leads to intrusion of a large volume of seawater. Directly after completion, the Sand Engine was constructed. This hook shaped sand peninsula will supply the coast with sand for the coming decades due to erosion and deposition along the coast. These two large coastal defense projects would obviously influence the tightly balanced hydrological system of Monster. Without hydrological intervention, the drinking water production would no longer be sustainable in this area. To study the effects of these projects and to find a solution to combine coastal defense and drinking water supply, field research and effect (geochemical) modeling were used interactively. To prevent negative effects it was decided to construct interception wells on top of the new dune ridge (28 in total). A comprehensive monitoring system was built to keep track of the salt groundwater and the groundwater heads. The zero measurement included groundwater heads, water samples, but also geophysical methods such as SkyTEM and CVES. We will also show the monitoring system we use to keep track of the groundwater heads and salt water intrusion in the future.

Schaars, Frans; Hoogmoed, Merel; van Vliet, Frank; Stuyfzand, Pieter; Groen, Michel; van der Made, Kees-Jan; Caljé, Ruben; Auken, Esben; Bergsted Pedersen, Jesper

2013-04-01

257

Epidemiology of HBV subgenotypes D.  

PubMed

The natural history of hepatitis B virus infection is not uniform and affected from several factors including, HBV genotype. Genotype D is a widely distributed genotype. Among genotype D, several subgenotypes differentiate epidemiologically and probably clinically. D1 is predominant in Middle East and North Africa, and characterized by early HBeAg seroconversion and low viral load. D2 is seen in Albania, Turkey, Brazil, western India, Lebanon, and Serbia. D3 was reported from Serbia, western India, and Indonesia. It is a predominant subgenotype in injection drug use-related acute HBV infections in Europe and Canada. D4 is relatively rare and reported from Haiti, Russia and Baltic region, Brazil, Kenya, Morocco and Rwanda. Subgenotype D5 seems to be common in Eastern India. D6 has been reported as a rare subgenotype from Indonesia, Kenya, Russia and Baltic region. D7 is the main genotype in Morocco and Tunisia. D8 and D9 are recently described subgenotypes and reported from Niger and India, respectively. Subgenotypes of genotype D may have clinical and/or viral differences. More subgenotype studies are required to conclude on subgenotype and its clinical/viral characteristics. PMID:25037178

Ozaras, Resat; Inanc Balkan, Ilker; Yemisen, Mucahit; Tabak, Fehmi

2015-02-01

258

On the hydrologic adjustment of climate-model projections: The potential pitfall of potential evapotranspiration  

USGS Publications Warehouse

Hydrologic models often are applied to adjust projections of hydroclimatic change that come from climate models. Such adjustment includes climate-bias correction, spatial refinement ("downscaling"), and consideration of the roles of hydrologic processes that were neglected in the climate model. Described herein is a quantitative analysis of the effects of hydrologic adjustment on the projections of runoff change associated with projected twenty-first-century climate change. In a case study including three climate models and 10 river basins in the contiguous United States, the authors find that relative (i.e., fractional or percentage) runoff change computed with hydrologic adjustment more often than not was less positive (or, equivalently, more negative) than what was projected by the climate models. The dominant contributor to this decrease in runoff was a ubiquitous change in runoff (median 211%) caused by the hydrologic model's apparent amplification of the climate-model-implied growth in potential evapotranspiration. Analysis suggests that the hydrologic model, on the basis of the empirical, temperature-based modified Jensen-Haise formula, calculates a change in potential evapotranspiration that is typically 3 times the change implied by the climate models, which explicitly track surface energy budgets. In comparison with the amplification of potential evapotranspiration, central tendencies of other contributions from hydrologic adjustment (spatial refinement, climate-bias adjustment, and process refinement) were relatively small. The authors' findings highlight the need for caution when projecting changes in potential evapotranspiration for use in hydrologic models or drought indices to evaluate climatechange impacts on water. Copyright ?? 2011, Paper 15-001; 35,952 words, 3 Figures, 0 Animations, 1 Tables.

Milly, P.C.D.; Dunne, K.A.

2011-01-01

259

Integration of models for better quantification of urban hydrology: Coupling urban drainage system models and distributed groundwater models  

NASA Astrophysics Data System (ADS)

There is a growing need to simulate and predict hydrological system responses in urban environments as infrastructure becomes increasingly threatened by the effects of climate change (e.g. more frequent and severe flooding). Urban hydrology can cause flooding by drainage systems reaching maximum capacity, precipitation exceeding soil infiltration capacity, groundwater rising above surface, or a combination of these processes. The high complexity of urban hydrology is strained by the interaction between natural hydrological systems with precipitation, overland flow, recharge, groundwater flow, and drainage systems with routing of water from paved areas toward finite drainage networks. In order to asses flood risks in the urban environment, a modelling system integrating the different interacting parts in the urban hydrology should be applied. In the presented study a well-known drainage water and sewage water model, MIKE URBAN based on MOUSE is coupled with a spatially distributed groundwater - surface water model including vadoze zone processes. The primary objective for the study is to improve subsurface urban hydrological predictability because previous studies have illustrated the incapability of a stand-alone groundwater model to simulate measured groundwater head variability beneath an urbanized area. The investigated urban area is located in the western part of Denmark where urban infrastructure is vulnerable against high groundwater levels. Groundwater head predictions benefit from the coupled modelling approach where paved urban zones (with drainage runoff) and green areas (with more naturally occurring recharge) are separated, thereby affecting dynamic groundwater levels.

Kidmose, J.; Troldborg, L.; Refsgaard, J.; Randall, M. T.

2012-12-01

260

Remote sensing and hydrological modeling of burn scars  

NASA Astrophysics Data System (ADS)

This study examined the potential usefulness of combining remote sensing data with hydrologic models and mapping tools available from Geographic Information Systems (GIS), to evaluate the effects of wildfire. Four subprojects addressed this issue: (1) validation of burn scar maps derived from the Advanced Very High Resolution Radiometer (AVHRR) with the National Fire Occurrence Database; (2) testing the potential of thermal MODIS (Moderate Resolution Imaging Spectroradiometer) data for near-real time burn scar and fire severity mapping; (3) evaluation of Landsat derived burn severity maps within WEPP through the Geo-spatial interface for the Water Erosion Prediction Project (GeoWEPP), and (4) predicting potential post-fire erosion for western U.S. forests utilizing existing datasets and models. Wildfire poses incredibly complex management problems in all of its stages. Today's land managers have the option of trying to mitigate the effects of a severe fire before it occurs by fuel management practices. This process is expensive especially considering the uncertainty of when and where the next fire in a given region will occur. When a wildfire does occur, deciding when to let it burn and when to suppress it may lead to controversial decisions. In addition to the threat to life and property from the fire itself, smoke emissions from large fires can cause air quality problems in distant airsheds. Even after the fire is extinguished, erosion and water quality problems may pose difficult management questions. Contributions stemming from these studies include improved burn scar maps for studying historical fire extent and demonstration of the feasibility of using thermal satellite data to predict burn scar extent when clouds and smoke obscure visible bands. The incorporation of Landsat derived burn severity maps was shown to improve post-fire erosion modeling results. Finally the potential post-fire burn severity and erosion risk maps generated for western US forests will be used for planning pre-fire fuel reduction treatments.

Miller, Mary Ellen

261

Hydrological modelling of a small catchment using SWAT-2000 Ensuring correct flow partitioning for contaminant modelling  

NASA Astrophysics Data System (ADS)

SummaryThe performance of the SWAT-2000 model was evaluated using stream flow at the outlet of the 142 ha Colworth catchment (Bedfordshire, UK). This catchment has been monitored since October 1999. The soil type consists of clay loam soil over stony calcareous clay and a rotation of wheat, oil seed rape, grass, beans and peas is grown. Much of the catchment is tile drained. Acceptable performance in hydrological modelling, along with correct simulation of the processes driving the water balance were essential first requirements for predicting contaminant transport. Initial results from SWAT-2000 identified some necessary modifications in the model source code for correct simulation of processes driving water balance. After modification of the code, hydrological simulation, crop growth and evapotranspiration (ET) patterns were realistic when compared with empirical data. Acceptable model performance (based on a number of error measures) was obtained in final model runs, with reasonable runoff partitioning into overland flow, tile drainage and base flow.

Kannan, N.; White, S. M.; Worrall, F.; Whelan, M. J.

2007-02-01

262

Evaluating and developing parameter optimization and uncertainty analysis methods for a computationally intensive distributed hydrological model  

E-print Network

This study focuses on developing and evaluating efficient and effective parameter calibration and uncertainty methods for hydrologic modeling. Five single objective optimization algorithms and six multi-objective optimization algorithms were tested...

Zhang, Xuesong

2009-05-15

263

Coupled Atmosphere-Biophysics-Hydrology Models for Environmental Modeling  

Microsoft Academic Search

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

Robert L. Walko; Larry E. Band; Jill Baron; Timothy G. F. Kittel; Richard Lammers; Tsengdar J. Lee; Dennis Ojima; Roger A. Pielke Sr.; Chris Taylor; Christina Tague; Craig J. Tremback; Pier Luigi Vidale

2000-01-01

264

Land surface hydrology parameterization for atmospheric general circulation models including subgrid scale spatial variability  

NASA Technical Reports Server (NTRS)

Parameterizations are developed for the representation of subgrid hydrologic processes in atmospheric general circulation models. Reasonable a priori probability density functions of the spatial variability of soil moisture and of precipitation are introduced. These are used in conjunction with the deterministic equations describing basic soil moisture physics to derive expressions for the hydrologic processes that include subgrid scale variation in parameters. The major model sensitivities to soil type and to climatic forcing are explored.

Entekhabi, D.; Eagleson, P. S.

1989-01-01

265

Parsimonious Hydrologic and Nitrate Response Models For Silver Springs, Florida  

NASA Astrophysics Data System (ADS)

Silver Springs with an approximate discharge of 25 m3/sec is one of Florida's first magnitude springs and among the largest springs worldwide. Its 2500-km2 springshed overlies the mostly unconfined Upper Floridan Aquifer. The aquifer is approximately 100 m thick and predominantly consists of porous, fractured and cavernous limestone, which leads to excellent surface drainage properties (no major stream network other than Silver Springs run) and complex groundwater flow patterns through both rock matrix and fast conduits. Over the past few decades, discharge from Silver Springs has been observed to slowly but continuously decline, while nitrate concentrations in the spring water have enormously increased from a background level of 0.05 mg/l to over 1 mg/l. In combination with concurrent increases in algae growth and turbidity, for example, and despite an otherwise relatively stable water quality, this has given rise to concerns about the ecological equilibrium in and near the spring run as well as possible impacts on tourism. The purpose of the present work is to elaborate parsimonious lumped parameter models that may be used by resource managers for evaluating the springshed's hydrologic and nitrate transport responses. Instead of attempting to explicitly consider the complex hydrogeologic features of the aquifer in a typically numerical and / or stochastic approach, we use a transfer function approach wherein input signals (i.e., time series of groundwater recharge and nitrate loading) are transformed into output signals (i.e., time series of spring discharge and spring nitrate concentrations) by some linear and time-invariant law. The dynamic response types and parameters are inferred from comparing input and output time series in frequency domain (e.g., after Fourier transformation). Results are converted into impulse (or step) response functions, which describe at what time and to what magnitude a unitary change in input manifests at the output. For the hydrologic response model, frequency spectra of groundwater recharge and spring discharge suggest an exponential response model, which may explain a significant portion of spring discharge variability with only two fitting parameters (mean response time 2.4 years). For the transport model, direct use of nitrate data is confounded by inconsistent data and a strong trend. Instead, chloride concentrations in rainfall and at the spring are investigated as a surrogate candidate. Preliminary results indicate that the transport response function of the springshed as a whole may be of the gamma type, which possesses both a larger initial peak as well as a longer tail than the exponential response function. This is consistent with the large range of travel times to be expected between input directly into fast conduits connected to the spring (e.g., though sinkholes) and input or back-diffusion from the rock matrix. The result implies that reductions in nitrate input, especially at remote and hydraulically not well connected locations, will only manifest in a rather delayed and smoothed out form in concentration observed at the spring.

Klammler, Harald; Yaquian-Luna, Jose Antonio; Jawitz, James W.; Annable, Michael D.; Hatfield, Kirk

2014-05-01

266

Addressing the Challenges of Distributed Hydrologic Modeling for Operational Forecasting  

NASA Astrophysics Data System (ADS)

Operational forecasting systems must provide reliable, accurate and timely flood forecasts for a range of catchments from small rapidly responding mountain catchments and urban areas to large, complex but more slowly responding fluvial systems. Flood forecasting systems have evolved from simple forecasting for flood mitigation to real-time decision support systems for real-time reservoir operations for water supply, navigation, hydropower, for managing environmental flows and habitat protection, cooling water and water quality forecasting. These different requirements lead to a number of challenges in applying distributed modelling in an operational context. These challenges include, the often short time available for forecasting that requires a trade-off between model complexity and accuracy on the one hand and on the other hand the need for efficient calculations to reduce the computation times. Limitations in the data available in real-time require modelling tools that can not only operate on a minimum of data but also take advantage of new data sources such as weather radar, satellite remote sensing, wireless sensors etc. Finally, models must not only accurately predict flood peaks but also forecast low flows and surface water-groundwater interactions, water quality, water temperature, optimal reservoir levels, and inundated areas. This paper shows how these challenges are being addressed in a number of case studies. The central strategy has been to develop a flexible modelling framework that can be adapted to different data sources, different levels of complexity and spatial distribution and different modelling objectives. The resulting framework allows amongst other things, optimal use of grid-based precipitation fields from weather radar and numerical weather models, direct integration of satellite remote sensing, a unique capability to treat a range of new forecasting problems such as flooding conditioned by surface water-groundwater interactions. Results from flood modelling on the Odra River in Poland show that this model system can perform as well as traditional models and gives good predictions in mountainous catchments. By allowing different process representations to be applied within the same framework, it is possible to develop hydrological models in a phased manner. This phased approach was used for example in the Napa Valley, California where it is important to balance water demands for urban areas, agriculture, and ecosystem preservation while maintaining flood protection and water quality. A first regional model was developed with a detailed description of the surface process and a simple linear reservoir was used to simulate the groundwater component. Then a more detailed fully-distributed finite-difference groundwater model was constructed within the same framework while maintaining the surface water components. In the DMIP case study, Blue River, Oklahoma, this flexibility has been used to evaluate the performance of different model structures, and to determine the impact of grid resolution on model accuracy. The results show clear limits to the benefit attained by increasing model complexity and resolution. In contrast, detailed flood mapping using high resolution topography carried out with this tool in South Boulder Creek, Colorado show that very detailed description of the topography and flows paths are required for accurate flood mapping and determination of the flood risk. This framework is now being used to develop a flood forecasting system for the Big Cypress Basin in Florida.

Butts, M. B.; Yamagata, K.; Kobor, J.; Fontenot, E.

2008-05-01

267

Possible origins and evolution of the hepatitis B virus (HBV).  

PubMed

All members of the family Hepadnaviridae are primarily viruses which contain double-stranded DNA genomes that are replicated via reverse transcription of a pregenomic RNA template. There are two subgroups within this family: mammalian and avian. The avian member's include the duck hepatitis B virus (DHBV), heron hepatitis B virus, Ross goose hepatitis B virus, stork hepatitis B virus and the recently identified parrot hepatitis B virus. More recently, the detection of endogenous avian hepadnavirus DNA integrated into the genomes of zebra finches has revealed a deep evolutionary origin of hepadnaviruses that was not previously recognised, dating back over 40 million years ago. The non-primate mammalian members of the Hepadnaviridae include the woodchuck hepatitis virus (WHV), the ground squirrel hepatitis virus and arctic squirrel virus, as well as the recently described bat hepatitis virus. The identification of hepatitis B virus (HBV) in higher primates such as chimpanzee, gorilla, orangutan, and gibbons that cluster with the human genotypes further implies a more complex origin of this virus. By studying the molecular epidemiology of HBV in indigenous and relict populations in Asia-Pacific we propose a model for the origin and evolution of HBV that involves multiple cross-species transmissions and subsequent recombination events on a background of genotype C HBV infection. PMID:24013024

Locarnini, Stephen; Littlejohn, Margaret; Aziz, Muhammad Nazri; Yuen, Lilly

2013-12-01

268

Marrying Hydrological Modelling and Integrated Assessment for the needs of Water Resource Management  

NASA Astrophysics Data System (ADS)

This paper discusses the integration of hydrology with other disciplines using an Integrated Assessment (IA) and modelling approach to the management and allocation of water resources. Recent developments in the field of socio-hydrology aim to develop stronger relationships between hydrology and the human dimensions of Water Resource Management (WRM). This should build on an existing wealth of knowledge and experience of coupled human-water systems. To further strengthen this relationship and contribute to this broad body of knowledge, we propose a strong and durable "marriage" between IA and hydrology. The foundation of this marriage requires engagement with appropriate concepts, model structures, scales of analyses, performance evaluation and communication - and the associated tools and models that are needed for pragmatic deployment or operation. To gain insight into how this can be achieved, an IA case study in water allocation in the Lower Namoi catchment, NSW, Australia is presented.

Croke, B. F. W.; Blakers, R. S.; El Sawah, S.; Fu, B.; Guillaume, J. H. A.; Kelly, R. A.; Patrick, M. J.; Ross, A.; Ticehurst, J.; Barthel, R.; Jakeman, A. J.

2014-09-01

269

Improved ground hydrology calculations for global climate models (GCMs) - Soil water movement and evapotranspiration  

NASA Technical Reports Server (NTRS)

A physically based ground hydrology model is presented that includes the processes of transpiration, evaporation from intercepted precipitation and dew, evaporation from bare soil, infiltration, soil water flow, and runoff. Data from the Goddard Institute for Space Studies GCM were used as inputs for off-line tests of the model in four 8 x 10 deg regions, including Brazil, Sahel, Sahara, and India. Soil and vegetation input parameters were caculated as area-weighted means over the 8 x 10 deg gridbox; the resulting hydrological quantities were compared to ground hydrology model calculations performed on the 1 x 1 deg cells which comprise the 8 x 10 deg gridbox. Results show that the compositing procedure worked well except in the Sahel, where low soil water levels and a heterogeneous land surface produce high variability in hydrological quantities; for that region, a resolution better than 8 x 10 deg is needed.

Abramopoulos, F.; Rosenzweig, C.; Choudhury, B.

1988-01-01

270

Coupled forest growth-hydrology modelling as an instrument for the assessment of effects of forest management on hydrology in forested catchments  

NASA Astrophysics Data System (ADS)

The type and intensity of forest management directly influences regional catchment hydrology. Future forest management must optimise the effects of its practices to achieve sustainable management. With scenario analysis of forestry practices, the effects of different forest utilisation strategies on the hydrology of forested catchments can be temporally and spatially quantified. The approach adopted in this study necessitated the development of an interactive system for the spatially distributed modelling of hydrology in relation to forest stand development. Consequently, a forest growth model was used to simulate stand development assuming various forest management activities. Selected simulated forest growth parameters were entered into the hydrological model to simulate water fluxes under different conditions of forest structure. The approach enables the spatially differentiated quantification of changes in the water regime (e.g. increased evapotranspiration). The results of hydrological simulations in the study area, the Oker catchment (northern Harz Mountains), show that forests contribute to the protection of water systems because they have a balancing effect on the hydrological regime. As scenario simulations also suggest, however, forestry practices can also lead to substantial changes in water budgets of forested catchments. The preservation of the hydrological services of forests requires a sustainable and long-term forest conversion on the basis of current management directives for near natural silviculture. Management strategies on basis of moderate harvesting regimes are preferred because of their limited impact on the water budget.

Sutmöller, J.; Hentschel, S.; Hansen, J.; Meesenburg, H.

2011-03-01

271

A generic theory for hydrologic modeling: An approach based on complex networks  

NASA Astrophysics Data System (ADS)

The search for a generic theory for hydrologic systems has been a long-standing endeavor. One of the key requirements for developing a generic theory for hydrologic systems is an adequate knowledge of the connections among the various components at a broad range of spatial and temporal scales. Despite our progress so far through development and application of various scientific approaches and mathematical techniques, our understanding of such connections remains largely inadequate. The present study argues that the science of complex networks serves as a bridge between the top-down approaches and the bottom-up approaches and offers a generic theory for studying all connections associated with hydrologic systems. First, the history of network theory and the basic concepts and measures of complex networks are reviewed. Next, the relevance of complex networks for studying connections in hydrologic systems is explained through several examples, including the hydrologic cycle, rainfall and streamflow monitoring networks, global climate model (GCM) outputs, and river networks. Then, the usefulness of the ideas of complex networks in hydrology is tested through their application to streamflow data monitoring networks in the United States, focusing on spatial variability, interpolation/extrapolation, and catchment classification. Finally, the implications of the outcomes of this analysis for hydrologic modeling and prediction, and for water resources planning and management at the broader scale, are also discussed.

Sivakumar, Bellie

2014-05-01

272

Evaluating the Hydrologic Sensitivities of Three Land Surface Models to Bound Uncertainties in Runoff Projections  

NASA Astrophysics Data System (ADS)

Hydrologic modeling is often used to assess the potential impacts of climate change on water availability and quality. A common approach in these studies is to calibrate the selected model(s) to reproduce historic stream flows prior to the application of future climate projections. This approach relies on the implicit assumptions that the sensitivities of these models to meteorological fluctuations will remain relatively constant under climate change and that these sensitivities are similar among models if all models are calibrated to the same historic record. However, even if the models are able to capture the historic variability in hydrological variables, differences in model structure and parameter estimation contribute to the uncertainties in projected runoff, which confounds the incorporation of these results into water resource management decision-making. A better understanding of the variability in hydrologic sensitivities between different models can aid in bounding this uncertainty. In this research, we characterized the hydrologic sensitivities of three watershed-scale land surface models through a case study of the Bull Run watershed in Northern Oregon. The Distributed Hydrology Soil Vegetation Model (DHSVM), Precipitation-Runoff Modeling System (PRMS), and Variable Infiltration Capacity model (VIC) were implemented and calibrated individually to historic streamflow using a common set of long-term, gridded forcings. In addition to analyzing model performances for a historic period, we quantified the temperature sensitivity (defined as change in runoff in response to change in temperature) and precipitation elasticity (defined as change in runoff in response to change in precipitation) of these three models via perturbation of the historic climate record using synthetic experiments. By comparing how these three models respond to changes in climate forcings, this research aims to test the assumption of constant and similar hydrologic sensitivities. Our results shed light on the uncertainties associated with hydrologic models and should contribute to meaningful interpretation of streamflow projection results for water management applications. However, the eventual decision by water managers as to which hydrologic model to select often includes other variables important to the agency's ability to operate and utilize the hydrologic model.

Chiao, T.; Nijssen, B.; Stickel, L.; Lettenmaier, D. P.

2013-12-01

273

A simple hydrologically based model of land surface water and energy fluxes for general circulation models  

NASA Technical Reports Server (NTRS)

A generalization of the single soil layer variable infiltration capacity (VIC) land surface hydrological model previously implemented in the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation model (GCM) is described. The new model is comprised of a two-layer characterization of the soil column, and uses an aerodynamic representation of the latent and sensible heat fluxes at the land surface. The infiltration algorithm for the upper layer is essentially the same as for the single layer VIC model, while the lower layer drainage formulation is of the form previously implemented in the Max-Planck-Institut GCM. The model partitions the area of interest (e.g., grid cell) into multiple land surface cover types; for each land cover type the fraction of roots in the upper and lower zone is specified. Evapotranspiration consists of three components: canopy evaporation, evaporation from bare soils, and transpiration, which is represented using a canopy and architectural resistance formulation. Once the latent heat flux has been computed, the surface energy balance is iterated to solve for the land surface temperature at each time step. The model was tested using long-term hydrologic and climatological data for Kings Creek, Kansas to estimate and validate the hydrological parameters, and surface flux data from three First International Satellite Land Surface Climatology Project Field Experiment (FIFE) intensive field campaigns in the summer-fall of 1987 to validate the surface energy fluxes.

Liang, XU; Lettenmaier, Dennis P.; Wood, Eric F.; Burges, Stephen J.

1994-01-01

274

Simulation of groundwater and surface water over the continental US using a hyperresolution, integrated hydrologic model  

NASA Astrophysics Data System (ADS)

Interactions between surface and groundwater systems are well-established theoretically and observationally. While numerical models that solve both surface and subsurface flow equations in a single framework (matrix) are increasingly being applied, computational limitations have restricted their use to local and regional studies. Regional or watershed, scale simulations have been effective tools in understanding hydrologic processes, however there are still many questions, such as the adaptation of water resources to anthropogenic stressors and climate variability, that need to be answered across large spatial extents at high resolution. In response to this "grand challenge" in hydrology, we present the results of a parallel, integrated hydrologic model simulating surface and subsurface flow at high spatial resolution (1 km) over much of continental North America (~ 6 300 000 or 6.3 million km2). These simulations provide predictions of hydrologic states and fluxes, namely water table depth and streamflow, at unprecedented scale and resolution. The physically-based modeling approach used here requires limited parameterizations and relies only on more fundamental inputs, such as topography, hydrogeologic properties and climate forcing. Results are compared to observations and provide mechanistic insight into hydrologic process interaction. This study demonstrates both the feasibility of continental scale integrated models and their utility for improving our understanding of large-scale hydrologic systems; the combination of high resolution and large spatial extent facilitates novel analysis of scaling relationships using model outputs.

Maxwell, R. M.; Condon, L. E.; Kollet, S. J.

2014-11-01

275

On the prediction of the Toce alpine basin floods with distributed hydrologic models  

NASA Astrophysics Data System (ADS)

With the objective of improving flood predictions, in recent years sophisticated continuous hydrologic models that include complex land-surface sub-models have been developed. This has produced a significant increase in parameterization; consequently, applications of distributed models to ungauged basins lacking specific data from field campaigns may become redundant.The objective of this paper is to produce a parsimonious and robust distributed hydrologic model for flood predictions in Italian alpine basins. Application is made to the Toce basin (area 1534 km2). The Toce basin was a case study of the RAPHAEL European Union research project, during which a comprehensive set of hydrologic, meteorological and physiographic data were collected, including the hydrologic analysis of the 1996-1997 period. Two major floods occurred during this period. We compare the FEST04 event model (which computes rainfall abstraction and antecedent soil moisture conditions through the simple Soil Conservation Service curve number method) and two continuous hydrologic models, SDM and TDM (which differ in soil water balance scheme, and base flow and runoff generation computations).The simple FEST04 event model demonstrated good performance in the prediction of the 1997 flood, but shows limits in the prediction of the long and moderate 1996 flood. More robust predictions are obtained with the parsimonious SDM continuous hydrologic model, which uses a simple one-layer soil water balance model and an infiltration excess mechanism for runoff generation, and demonstrates good performance in both long-term runoff modelling and flood predictions. Instead, the use of a more sophisticated continuous hydrologic model, the TDM, that simulates soil moisture dynamics in two layers of soil, and computes runoff and base flow using some TOPMODEL concepts, does not seem to be advantageous for this alpine basin. Copyright

Montaldo, Nicola; Ravazzani, Giovanni; Mancini, Marco

2007-02-01

276

Stepwise calibration procedure for regional coupled hydrological-hydrogeological models  

NASA Astrophysics Data System (ADS)

Stream-aquifer interaction is a complex process depending on regional and local processes. Indeed, the groundwater component of hydrosystem and large scale heterogeneities control the regional flows towards the alluvial plains and the rivers. In second instance, the local distribution of the stream bed permeabilities controls the dynamics of stream-aquifer water fluxes within the alluvial plain, and therefore the near-river piezometric head distribution. In order to better understand the water circulation and pollutant transport in watersheds, the integration of these multi-dimensional processes in modelling platform has to be performed. Thus, the nested interfaces concept in continental hydrosystem modelling (where regional fluxes, simulated by large scale models, are imposed at local stream-aquifer interfaces) has been presented in Flipo et al (2014). This concept has been implemented in EauDyssée modelling platform for a large alluvial plain model (900km2) part of a 11000km2 multi-layer aquifer system, located in the Seine basin (France). The hydrosystem modelling platform is composed of four spatially distributed modules (Surface, Sub-surface, River and Groundwater), corresponding to four components of the terrestrial water cycle. Considering the large number of parameters to be inferred simultaneously, the calibration process of coupled models is highly computationally demanding and therefore hardly applicable to a real case study of 10000km2. In order to improve the efficiency of the calibration process, a stepwise calibration procedure is proposed. The stepwise methodology involves determining optimal parameters of all components of the coupled model, to provide a near optimum prior information for the global calibration. It starts with the surface component parameters calibration. The surface parameters are optimised based on the comparison between simulated and observed discharges (or filtered discharges) at various locations. Once the surface parameters have been determined, the groundwater component is calibrated. The calibration procedure is performed under steady state hypothesis (to minimize the procedure time length) using recharge rates given by the surface component calibration and imposed fluxes boundary conditions given by the regional model. The calibration is performed using pilot point where the prior variogram is calculated from observed transmissivities values. This procedure uses PEST (http//:www.pesthomepage.org/Home.php) as the inverse modelling tool and EauDyssée as the direct model. During the stepwise calibration process, each modules, even if they are actually dependant from each other, are run and calibrated independently, therefore contributions between each module have to be determined. For the surface module, groundwater and runoff contributions have been determined by hydrograph separation. Among the automated base-flow separation methods, the one-parameter Chapman filter (Chapman et al 1999) has been chosen. This filter is a decomposition of the actual base-flow between the previous base-flow and the discharge gradient weighted by functions of the recession coefficient. For the groundwater module, the recharge has been determined from surface and sub-surface module. References : Flipo, N., A. Mourhi, B. Labarthe, and S. Biancamaria (2014). Continental hydrosystem modelling : the concept of nested stream-aquifer interfaces. Hydrol. Earth Syst. Sci. Discuss. 11, 451-500. Chapman,TG. (1999). A comparison of algorithms for stream flow recession and base-flow separation. hydrological Processes 13, 701-714.

Labarthe, Baptiste; Abasq, Lena; de Fouquet, Chantal; Flipo, Nicolas

2014-05-01

277

Therapeutic vaccines in HBV: lessons from HCV.  

PubMed

Currently, millions of people infected with hepatitis B virus (HBV) are committed to decades of treatment with anti-viral therapy to control viral replication. However, new tools for immunotherapy that include both viral vectors and molecular checkpoint inhibitors are now available. This has led to a resurgence of interest in new strategies to develop immunotherapeutic strategies with the aim of inducing HBeAg seroconversion-an end-point that has been associated with a decrease in the rates of disease progression. Ultimately, a true cure will involve the elimination of covalently closed circular DNA which presents a greater challenge for immunotherapy. In this manuscript, I describe the development of immunotherapeutic strategies for HBV that are approaching or currently in clinical studies, and draw on observations of T cell function in natural infection supported by recent animal studies that may lead to additional rational vaccine strategies using checkpoint inhibitors. I also draw on our recent experience in developing potent vaccines for HCV prophylaxis based on simian adenoviral and MVA vectors used in prime-boost strategies in both healthy volunteers and HCV infected patients. I have shown that the induction of T cell immune responses is markedly attenuated when administered to people with persistent HCV viremia. These studies and recently published animal studies using the woodchuck model suggest that potent vaccines based on DNA or adenoviral vectored vaccination represent a rational way forward. However, combining these with drugs to suppress viral replication, alongside checkpoint inhibitors may be required to induce long-term immune control. PMID:25573348

Barnes, Eleanor

2015-02-01

278

Modeling the effect of glacier recession on streamflow response using a coupled glacio-hydrological model  

NASA Astrophysics Data System (ADS)

We describe an integrated spatially distributed hydrologic and glacier dynamic model, and use it to investigate the effect of glacier recession on streamflow variations for the upper Bow River basin, a tributary of the South Saskatchewan River, Alberta, Canada. Several recent studies have suggested that observed decreases in summer flows in the South Saskatchewan River are partly due to the retreat of glaciers in the river's headwaters. Modeling the effect of glacier changes on streamflow response in river basins such as the South Saskatchewan is complicated due to the inability of most existing physically based distributed hydrologic models to represent glacier dynamics. We compare predicted variations in glacier extent, snow water equivalent (SWE), and streamflow discharge with satellite estimates of glacier area and terminus position, observed glacier mass balance, observed streamflow and snow water-equivalent measurements, respectively over the period of 1980-2007. Observations of multiple hydroclimatic variables compare well with those simulated with the coupled hydrology-glacier model. Our results suggest that, on average, the glacier melt contribution to the Bow River flow upstream of Lake Louise is approximately 22% in summer. For warm and dry years, however, the glacier melt contribution can be as large as 47% in August, whereas for cold years, it can be as small as 15% and the timing of the glacier melt signature can be delayed by a month. The development of this modeling approach sets the stage for future predictions of the influence of warming climate on streamflow in partially glacierized watersheds.

Naz, B. S.; Frans, C. D.; Clarke, G. K. C.; Burns, P.; Lettenmaier, D. P.

2014-02-01

279

Modeling the effect of glacier recession on streamflow response using a coupled glacio-hydrological model  

NASA Astrophysics Data System (ADS)

We describe an integrated spatially distributed hydrologic and glacier dynamic model, and use it to investigate the effect of glacier recession on streamflow variations for the Upper Bow River basin, a tributary of the South Saskatchewan River. Several recent studies have suggested that observed decreases in summer flows in the South Saskatchewan River are partly due to the retreat of glaciers in the river's headwaters. Modeling the effect of glacier changes on streamflow response in river basins such as the South Saskatchewan is complicated due to the inability of most existing physically-based distributed hydrologic models to represent glacier dynamics. We compare predicted variations in glacier extent, snow water equivalent and streamflow discharge made with the integrated model with satellite estimates of glacier area and terminus position, observed streamflow and snow water equivalent measurements over the period of 1980-2007. Simulations with the coupled hydrology-glacier model reduce the uncertainty in streamflow predictions. Our results suggested that on average, the glacier melt contribution to the Bow River flow upstream of Lake Louise is about 30% in summer. For warm and dry years, however, the glacier melt contribution can be as large as 50% in August, whereas for cold years, it can be as small as 20% and the timing of glacier melt signature can be delayed by a month.

Naz, B. S.; Frans, C. D.; Clarke, G. K. C.; Burns, P.; Lettenmaier, D. P.

2013-04-01

280

Modeling the effect of glacier recession on streamflow response using a coupled glacio-hydrological model  

SciTech Connect

We describe an integrated spatially distributed hydrologic and glacier dynamic model, and use it to investigate the effect of glacier recession on streamflow variations for the Upper Bow River basin, a tributary of the South Saskatchewan River. Several recent studies have suggested that observed decreases in summer flows in the South Saskatchewan River are partly due to the retreat of glaciers in the river's headwaters. Modeling the effect of glacier changes on streamflow response in river basins such as the South Saskatchewan is complicated due to the inability of most existing physically-based distributed hydrologic models to represent glacier dynamics. We compare predicted variations in glacier extent, snow water equivalent and streamflow discharge made with the integrated model with satellite estimates of glacier area and terminus position, observed streamflow and snow water equivalent measurements over the period of 1980 2007. Simulations with the coupled hydrology-glacier model reduce the uncertainty in streamflow predictions. Our results suggested that on average, the glacier melt contribution to the Bow River flow upstream of Lake Louise is about 30% in summer. For warm and dry years, however, the glacier melt contribution can be as large as 50% in August, whereas for cold years, it can be as small as 20% and the timing of glacier melt signature can be delayed by a month.

Naz, Bibi S [ORNL] [ORNL; Frans, Chris [University of Washington, Seattle] [University of Washington, Seattle; Clarke, Garry [University of British Columbia, Vancouver] [University of British Columbia, Vancouver; Burns, [Watershed Sciences Inc. (WSI), Portland] [Watershed Sciences Inc. (WSI), Portland; Lettenmaier, Dennis [University of Washington, Seattle] [University of Washington, Seattle

2014-01-01

281

Selection of hydrologic modeling approaches for climate change assessment: A comparison of model scale and structures  

NASA Astrophysics Data System (ADS)

SummaryA wide variety of approaches to hydrologic (rainfall-runoff) modeling of river basins confounds our ability to select, develop, and interpret models, particularly in the evaluation of prediction uncertainty associated with climate change assessment. To inform the model selection process, we characterized and compared three structurally-distinct approaches and spatial scales of parameterization to modeling catchment hydrology: a large-scale approach (using the VIC model; 671,000 km2 area), a basin-scale approach (using the PRMS model; 29,700 km2 area), and a site-specific approach (the GSFLOW model; 4700 km2 area) forced by the same future climate estimates. For each approach, we present measures of fit to historic observations and predictions of future response, as well as estimates of model parameter uncertainty, when available. While the site-specific approach generally had the best fit to historic measurements, the performance of the model approaches varied. The site-specific approach generated the best fit at unregulated sites, the large scale approach performed best just downstream of flood control projects, and model performance varied at the farthest downstream sites where streamflow regulation is mitigated to some extent by unregulated tributaries and water diversions. These results illustrate how selection of a modeling approach and interpretation of climate change projections require (a) appropriate parameterization of the models for climate and hydrologic processes governing runoff generation in the area under study, (b) understanding and justifying the assumptions and limitations of the model, and (c) estimates of uncertainty associated with the modeling approach.

Surfleet, Christopher G.; Tullos, Desirèe; Chang, Heejun; Jung, Il-Won

2012-09-01

282

Development of An Integrated Hydrologic Model in Yolo County, California  

NASA Astrophysics Data System (ADS)

To more efficiently use the Cache Creek flows and the groundwater basin as the sources of water supply and to restore the riparian ecosystem along the Cache Creek, Yolo County Flood Control and Water Conservation District (YCFCWCD) in Woodland, California plans to conduct the Cache Creek Groundwater Recharge and Recovery Program (CCGRRP). The concept of this program is to operate the groundwater basin to induce greater amounts of groundwater recharge from Cache Creek directly along the creek and to increase the recharge even further by diverting rainy season water at the District's Capay Diversion Dam into the West Adams Canal to a few recharge basins outside the active channel of Cache Creek. Besides the CCGRRP, cities of Woodland and Davis are in the process of conducting groundwater management plans, and the stakeholders in Yolo County developing a long-term integrated regional water management plan (IRWMP) for the entire county. To effectively evaluate the benefits and impacts of CCGRRP, local groundwater management plans, and the Yolo County IRWMP, the Integrated Groundwater and Surface water Model (IGSM) was applied to the Yolo groundwater basin. The IGSM is a comprehensive integrated hydrologic model that simulates both surface water and groundwater flow systems, including rainfall-runoff, soil moisture accounting and unsaturated flow, crop consumptive module, stream-aquifer interaction, and groundwater flow. The finite element code was originally developed in 1990 for the California Department of Water Resources and the State Water Resources Control Board. The IGSM code has subsequently been applied to more than 25 groundwater basins in California and other states. The model code has been peer reviewed and upgraded throughout its application to various projects, with the latest upgrade in 2004, as part of the application to the Stony Creek Fan area of Sacramento Valley. The Yolo County IGSM (YCIGSM) was calibrated against the historical (1970-2000) groundwater level records at 105 monitoring wells, and three streamflow gages along Cache Creek. Calibration results show that the YCIGSM is able to reasonably simulate the long-term groundwater level trends and short-term seasonal fluctuations. The YCIGSM will be used to develop operational guidelines to manage the groundwater basin, to determine the optimum yield of water projects, to identify benefits and impacts of projects on existing groundwater users, and to assess the environmental benefits and impacts during the development of projects, as well as during the environmental permitting process.

Liang, Y.; Taghavi, A.; Stevenson, M.; Najmus, S.

2006-12-01

283

Stable Isotope Tracers in Large Scale Hydrological Models  

Microsoft Academic Search

Stable isotopes of oxygen and hydrogen (deuterium and oxygen-18) have been shown to be effective tracers for characterizing hydrological processes in small river basins. Their application in large river basins has lagged behind due to the lack of sufficient isotope data. Recent availability of isotope data from most US rivers and subsequent efforts by the International Atomic Energy Agency (IAEA)

B. M. Fekete; P. Aggarwal

2004-01-01

284

Modeling winter hydrological processes under differing climatic conditions: Modifying WEPP  

Microsoft Academic Search

Water erosion is a serious and continuous environmental problem worldwide. In cold regions, soil freeze and thaw has great impacts on infiltration and erosion. Rain or snowmelt on a thawing soil can cause severe water erosion. Of equal importance is snow accumulation and snowmelt, which can be the predominant hydrological process in areas of mid- to high latitudes and forested

Shuhui Dun

2008-01-01

285

Integration of stream and watershed data for hydrologic modeling  

E-print Network

............................................................................13 2.2 GIS ? HYDROLOGIC PARAMETERS..................................................16 2.2.1 DEM-Based Methods...................................................................17 2.2.2 Vector-Based Methods....19 10m DEM for Bull Creek Basin.........................................................................104 5.20 Flow Gauging Station at Bull Creek@ Loop 360, Austin, TX..........................107 5.21 15 minute Precipitation File...

Koka, Srikanth

2004-09-30

286

Develop hydrological relationships using a modeling approach in Mississippi delta  

Technology Transfer Automated Retrieval System (TEKTRAN)

Agriculture management practices such as tillage and crop rotations alter the hydrological budget of watersheds. Changes happen to surface runoff can be easily identify with the help of intensive USGS stream gage network, available in Mississippi, but changes to ground water table is less understood...

287

A conceptual model of volume-change controls on the hydrology of cutover peats  

Microsoft Academic Search

Modeling hydrological processes in certain peats requires a detailed understanding of short-term changes in soil volume and it's influence on the system's hydraulic properties. A study of cutover sites abandoned for 7-years (H92) and 2-years (H97), and an undisturbed section of the Lac Saint-Jean (LSJ) cutover bog was conducted to characterize peat volume changes and its associated hydrological behaviour. Shrinkage

G. W. Kennedya

288

Modeling and Analysis of Global and Regional Climate Change in Relation to Atmospheric Hydrologic Processes  

NASA Technical Reports Server (NTRS)

This research was directed to the development and application of global isentropic modeling and analysis capabilities to describe hydrologic processes and energy exchange in the climate system, and discern regional climate change. An additional objective was to investigate the accuracy and theoretical limits of global climate predictability which are imposed by the inherent limitations of simulating trace constituent transport and the hydrologic processes of condensation, precipitation and cloud life cycles.

Johnson, Donald R.

2001-01-01

289

Parsimonious modeling of hydrologic responses in engineered watersheds: Structural heterogeneity versus functional homogeneity  

Microsoft Academic Search

The central premise of this paper is that extensive modifications of land use and hydrology, coupled with intensive management of watersheds in the Midwestern United States over the past century, have increased the predictability of hydrologic responses, allowing for the use of simpler, minimum-calibration models. In these engineered watersheds, extensive tile-and-ditch networks have increased the effective drainage density and have

Nandita B. Basu; P. S. C. Rao; H. Edwin Winzeler; Sanjiv Kumar; Phillip Owens; Venkatesh Merwade

2010-01-01

290

Exploring the Therapeutic Potentials of iNKT Cells for Anti-HBV Treatment.  

PubMed

CD1d-restricted invariant NKT (iNKT) cells are a group of innate-like regulatory T cells that recognize lipid antigens. Both mouse modeling experiments and human clinical studies have suggested a key role for iNKT cells in anti-HBV immunity and these potent T cells can be explored as a novel therapeutic target for anti-HBV treatment. We aim to humanize mice in the CD1d/iNKT cell lipid presentation system and provide new research tools for identifying novel anti-HBV agents. PMID:25438012

Lawrenczyk, Agnieszka; Kim, Seil; Wen, Xiangshu; Xiong, Ran; Yuan, Weiming

2014-01-01

291

Ensemble Kalman Filter Data Assimilation for the ParFlow Hydrologic Model  

NASA Astrophysics Data System (ADS)

Research in hydrometeorology has demonstrated repeatedly that atmospheric models benefit from detailed formulations of the land surface, and that energy and moisture fluxes between the land surface and atmosphere are coupled strongly not only with atmospheric conditions, but also with subsurface hydrology—particularly soil moisture distribution. Improving the representation of hydrologic processes should lead to better predictive skill in a fully-coupled weather forecasting model, and the hydrologic model itself can be improved by incorporating observed data values. For this work, we apply the Ensemble Kalman Filter functionality included in the Data Assimilation Assimilation Research Testbed (DART), a collection of data assimilation tools maintained at the National Center for Atmospheric Research, to the ParFlow hydrologic model—the hydrologic component of the TerrSysMP fully coupled hydrologic - land surface - atmospheric model system. This generalized data assimilation tool allows observations of variables in the hydrologic component of the system to be incorporated into the overall error covariance matrix thus guiding the development of quantities that define the model state. Single dimension column tests, two-dimensional hillslope tests, and a three-dimensional drainage and dry-out test were performed with the ParFlow-DART system to evaluate the effects of assimilating pressure head, soil moisture, and outflow observations on the development of the model through time. The success of these tests will allow the ParFlow-DART system to be developed into a complete data assimilation package for the TerrSysMP fully-coupled modeling system.

Williams, John

2014-05-01

292

Quantitative comparison of spatial fields for hydrological model assessment some promising approaches  

NASA Astrophysics Data System (ADS)

The current practice for assessing spatial predictions from distributed hydrological models is simplistic, with visual inspection and occasional point observations generally used for model assessment. With the increasing availability of spatial observations from remote sensing and intensive field studies, the current methods for assessing the spatial component of model predictions need to advance. This paper emphasises the role that spatial field comparisons can play in model assessment. A review of the current methods used in hydrology, and other disciplines where spatial field comparisons are widely used, reveals some promising methods for quantitatively comparing spatial fields. These promising approaches--segmentation, importance maps, fuzzy comparison and multiscale comparison--are for local comparison of spatial fields. They address some of the weaknesses with the current approaches to spatial field comparison used in hydrological modelling and, in doing so, emulate some aspects of human visual comparison. The potential of these approaches for assessing spatial predictions and understanding model performance is illustrated with a simple example.

Wealands, Stephen R.; Grayson, Rodger B.; Walker, Jeffrey P.

2005-01-01

293

Evaluating the SWAT Model for Hydrological Modeling in the Xixian Watershed and A Comparison with the XAJ Model  

SciTech Connect

Already declining water availability in Huaihe River, the 6th largest river in China, is further stressed by climate change and intense human activities. There is a pressing need for a watershed model to better understand the interaction between land use activities and hydrologic processes and to support sustainable water use planning. In this study, we evaluated the performance of SWAT for hydrologic modeling in the Xixian River Basin, located at the headwaters of the Huaihe River, and compared its performance with the Xinanjiang (XAJ) model that has been widely used in China

Shi, Peng; Chen, Chao; Srinivasan, Raghavan; Zhang, Xuesong; Cai, Tao; Fang, Xiuqin; Qu, Simin; Chen, Xi; Li, Qiongfang

2011-09-10

294

Influence of event characteristics on predictive uncertainty of a hydrological model  

NASA Astrophysics Data System (ADS)

An automated calibration and uncertainty estimation framework based on Monte Carlo sampling was developed and tested for its ability to estimate the predictive uncertainty of a semi-distributed hydro-ecological simulation model with respect to its hydrological predictions. This procedure was utilized for an adaptive predictive uncertainty estimation by classifying observed stream flow data into different event type classes that are similar in terms of dominant hydrological processes. Objective functions applied to the classified data were then used to calibrate the model, thereby adapting the calibration to different hydrological processes. The predictive uncertainty associated with each class of event was estimated by considering the acceptable model set as a fuzzy set of model realizations with the membership grade function equivalent to the corresponding calibration objective. Predictive uncertainty estimated using this technique showed considerable variation, but periods considered hydrologically similar, showed similar levels of predictive uncertainty. This approach also resulted in more refined and consistent identification of acceptable parameter sets compared to a traditional automated calibration. The results indicate that such a calibration technique has the potential to provide an estimate of relative predictive abilities of various submodels embedded within complex simulation models and provide a basis for testing model components and their interactions. However, a more robust event classification combined with suitable objective function definitions would be necessary to develop an event type based calibration technique that can be used for the purpose of characterizing the predictive uncertainty of a hydrological model.

Samanta, S.; Mackay, D. S.

2001-05-01

295

State updating of a distributed hydrological model with Ensemble Kalman Filtering: Effects of updating frequency and observation network density on forecast accuracy  

NASA Astrophysics Data System (ADS)

This paper presents a study on the optimal setup for discharge assimilation within a spatially distributed hydrological model (Rakovec et al., 2012a). The Ensemble Kalman filter (EnKF) is employed to update the grid-based distributed states of such an hourly spatially distributed version of the HBV-96 model. By using a physically based model for the routing, the time delay and attenuation are modelled more realistically. The discharge and states at a given time step are assumed to be dependent on the previous time step only (Markov property). Synthetic and real world experiments are carried out for the Upper Ourthe (1600 km2), a relatively quickly responding catchment in the Belgian Ardennes. The uncertain precipitation model forcings were obtained using a time-dependent multivariate spatial conditional simulation method (Rakovec et al., 2012b), which is further made conditional on preceding simulations. We assess the impact on the forecasted discharge of (1) various sets of the spatially distributed discharge gauges and (2) the filtering frequency. The results show that the hydrological forecast at the catchment outlet is improved by assimilating interior gauges. This augmentation of the observation vector improves the forecast more than increasing the updating frequency. In terms of the model states, the EnKF procedure is found to mainly change the pdfs of the two routing model storages, even when the uncertainty in the discharge simulations is smaller than the defined observation uncertainty. Rakovec, O., Weerts, A. H., Hazenberg, P., Torfs, P. J. J. F., and Uijlenhoet, R.: State updating of a distributed hydrological model with Ensemble Kalman Filtering: effects of updating frequency and observation network density on forecast accuracy, Hydrol. Earth Syst. Sci. Discuss., 9, 3961-3999, doi:10.5194/hessd-9-3961-2012, 2012a. Rakovec, O., Hazenberg, P., Torfs, P. J. J. F., Weerts, A. H., and Uijlenhoet, R.: Generating spatial precipitation ensembles: impact of temporal correlation structure, Hydrol. Earth Syst. Sci. Discuss., 9, 3087-3127, doi:10.5194/hessd-9-3087-2012, 2012b.

Rakovec, O.; Weerts, A.; Hazenberg, P.; Torfs, P.; Uijlenhoet, R.

2012-12-01

296

Assessing anthropogenic influence on the hydrology of small peri-urban catchments: Development of the object-oriented PUMMA model by integrating urban and rural hydrological models  

NASA Astrophysics Data System (ADS)

Distributed hydrological models are useful tools for process understanding and water management, especially in peri-urban catchments where the landscape heterogeneity is large, caused by a patchwork of natural and urbanized areas. This paper presents the Peri-Urban Model for landscape MAnagement (PUMMA) built within the LIQUID® modeling framework, specifically designed to study the hydrology of peri-urban catchments. It combines rural and urban hydrological models, and is used for process understanding. The originality of PUMMA is to follow a fully object-oriented approach, for both model mesh building and process representation. Urban areas, represented by cadastral units and rural areas divided in Hydrological Response Units are thus modeled with different interacting process modules. This provides a detailed representation of the runoff generation on natural and impervious areas. Furthermore, the exchange between process modules facilitates the simulation of subsurface and overland flow, as well as groundwater drainage by sewer pipes. Several drainage networks can coexist and interact (e.g. via storm water overflow devices) and water can be stored in retention basins, which allows the modeling of complex suburban drainage systems with multiple outlets. The model is then applied to the Chaudanne catchment (2.7 km2), located in the suburbs of Lyon, France. The uncalibrated model results show the importance of surface runoff from impervious areas for summer events and flow contributions from rural zones for winter events. Furthermore, the model reveals that the retention capacity of the Chaudanne catchment is larger than for classical urban catchments due to the peri-urban character of the catchment.

Jankowfsky, S.; Branger, F.; Braud, I.; Rodriguez, F.; Debionne, S.; Viallet, P.

2014-09-01

297

An ensemble modeling framework for understanding differences in hydrological model performance across the contiguous US  

NASA Astrophysics Data System (ADS)

Given rapid increases in computing power, the field of "large sample hydrology" is becoming increasingly popular as a way to understand model shortcomings and improve model performance. This presentation summarizes (1) development of an ensemble Contiguous United States (CONUS), gridded, daily, station based historical precipitation and temperature dataset used to understand how uncertainty in precipitation and temperature affects regional variability in hydrological model performance; and (2) analysis of the performance of the Snow17-Sacramento model for 670 basins across the contiguous USA. This work allows for characterization of model strengths and weaknesses over a large number of basins, spanning a wide range of hydro-climatic conditions. Analysis of the ensemble forcing data in an uncertainty framework provides an improved understanding of how climate station density and the hydro-climatic regime affect the relative importance of input data uncertainties and model structural weaknesses. Results show that model Nash-Sutcliffe efficiency (NSE), a popular measure of hydrologic model performance, varies regionally over the CONUS with skill in 90% of basins ranging from 0.55 to 0.94. Poor model performance is found in arid and semi-arid regions (e.g. high Plains of the U.S). Physically-based diagnostic measures show that, for example, low flow periods are generally over-predicted in rain-dominated basins and under-predicted in arid regions and basins with large seasonal snowpack. Reasons for poor NSE in arid and semi-arid basins point to uncertainties in the model forcing data and possible relationships between basin flashiness and forcing uncertainties. Future work will include a quantitative total error analysis using the Bayesian Total Error Analysis (BATEA) methodology.

Newman, Andy; Clark, Martyn; Wood, Andy; Craig, Jason; Sampson, Kevin; Hay, Lauren; Bock, Andy; Brekke, Levi; Arnold, Jeff

2014-05-01

298

A model of hydrological and mechanical feedbacks of preferential fissure flow in a slow-moving landslide  

NASA Astrophysics Data System (ADS)

The importance of hydrological processes for landslide activity is generally accepted. However, the relationship between precipitation, hydrological responses and movement is not straightforward. Groundwater recharge is mostly controlled by the hydrological material properties and the structure (e.g. layering, preferential flow paths such as fissures) of the unsaturated zone. In slow-moving landslides, differential displacements caused by the bedrock structure complicate the hydrological regime due to continuous opening and closing of the fissures, creating temporary preferential flow paths systems for infiltration and groundwater drainage. The consecutive opening and closing of fissure aperture control the formation of a critical pore water pressure by creating dynamic preferential flow paths for infiltration and groundwater drainage. This interaction may explain the seasonal nature of the slow-moving landslide activity, including the often observed shifts and delays in hydrological responses when compared to timing, intensity and duration of precipitation. The main objective of this study is to model the influence of fissures on the hydrological dynamics of slow-moving landslide and the dynamic feedbacks between fissures, hydrology and slope stability. For this we adapt the spatially distributed hydrological and slope stability model (STARWARS) to account for geotechnical and hydrological feedbacks, linking between hydrological response of the landside and the dynamics of the fissure network and applied the model to the hydrologically controlled Super-Sauze landslide (South French Alps).

Krzeminska, D. M.; Bogaard, T. A.; Malet, J.-P.; van Beek, L. P. H.

2012-10-01

299

A model of hydrological and mechanical feedbacks of preferential fissure flow in a slow-moving landslide  

NASA Astrophysics Data System (ADS)

The importance of hydrological processes for landslide activity is generally accepted. However, the relationship between precipitation, hydrological responses and movement is not straightforward. Groundwater recharge is mostly controlled by the hydrological material properties and the structure (e.g., layering, preferential flow paths such as fissures) of the unsaturated zone. In slow-moving landslides, differential displacements caused by the bedrock structure complicate the hydrological regime due to continuous opening and closing of the fissures, creating temporary preferential flow paths systems for infiltration and groundwater drainage. The consecutive opening and closing of fissure aperture control the formation of a critical pore water pressure by creating dynamic preferential flow paths for infiltration and groundwater drainage. This interaction may explain the seasonal nature of the slow-moving landslide activity, including the often observed shifts and delays in hydrological responses when compared to timing, intensity and duration of precipitation. The main objective of this study is to model the influence of fissures on the hydrological dynamics of slow-moving landslide and the dynamic feedbacks between fissures, hydrology and slope stability. For this we adapt the spatially distributed hydrological and slope stability model (STARWARS) to account for geotechnical and hydrological feedbacks, linking between hydrological response of the landside and the dynamics of the fissure network and applied the model to the hydrologically controlled Super-Sauze landslide (South French Alps).

Krzeminska, D. M.; Bogaard, T. A.; Malet, J.-P.; van Beek, L. P. H.

2013-03-01

300

Full implementation of a distributed hydrological model based on check dam trapped sediment volumes  

NASA Astrophysics Data System (ADS)

Lack of hydrometeorological data is one of the most compelling limitations to the implementation of distributed environmental models. Mediterranean catchments, in particular, are characterised by high spatial variability of meteorological phenomena and soil characteristics, which may prevents from transferring model calibrations from a fully gauged catchment to a totally o partially ungauged one. For this reason, new sources of data are required in order to extend the use of distributed models to non-monitored or low-monitored areas. An important source of information regarding the hydrological and sediment cycle is represented by sediment deposits accumulated at the bottom of reservoirs. Since the 60s, reservoir sedimentation volumes were used as proxy data for the estimation of inter-annual total sediment yield rates, or, in more recent years, as a reference measure of the sediment transport for sediment model calibration and validation. Nevertheless, the possibility of using such data for constraining the calibration of a hydrological model has not been exhaustively investigated so far. In this study, the use of nine check dam reservoir sedimentation volumes for hydrological and sedimentological model calibration and spatio-temporal validation was examined. Check dams are common structures in Mediterranean areas, and are a potential source of spatially distributed information regarding both hydrological and sediment cycle. In this case-study, the TETIS hydrological and sediment model was implemented in a medium-size Mediterranean catchment (Rambla del Poyo, Spain) by taking advantage of sediment deposits accumulated behind the check dams located in the catchment headwaters. Reservoir trap efficiency was taken into account by coupling the TETIS model with a pond trap efficiency model. The model was calibrated by adjusting some of its parameters in order to reproduce the total sediment volume accumulated behind a check dam. Then, the model was spatially validated by obtaining the simulated sedimentation volume at the other eight check dams and comparing it to the observed sedimentation volumes. Lastly, the simulated water discharge at the catchment outlet was compared with observed water discharge records in order to check the hydrological sub-model behaviour. Model results provided highly valuable information concerning the spatial distribution of soil erosion and sediment transport. Spatial validation of the sediment sub-model provided very good results at seven check dams out of nine. This study shows that check dams can be a useful tool also for constraining hydrological model calibration, as model results agree with water discharge observations. In fact, the hydrological model validation at a downstream water flow gauge obtained a Nash-Sutcliffe efficiency of 0.8. This technique is applicable to all catchments with presence of check dams, and only requires rainfall and temperature data and soil characteristics maps.

Bussi, Gianbattista; Francés, Félix

2014-05-01

301

Satellite remote sensing and hydrologic modeling for flood monitoring in data poor environments  

NASA Astrophysics Data System (ADS)

Study of hydroclimatology at a range of temporal scales is important in understanding and ultimately mitigating the potential severe impacts of hydrological extreme events such as floods and droughts. Using daily in-situ data combined with the recently available satellite remote sensing data, the hydroclimatology of Nzoia basin, one of the contributing sub-catchments of Lake Victoria in the East African highlands is analyzed. The basin, with a semi-arid climate, has no sustained base flow contribution to Lake Victoria. The short spell of high discharge showed that rain is the primary cause of floods in the basin. There is only a marginal increase in annual mean discharge over the last 21 years. The 2-, 5- and 10- year peak discharges, for the entire study period showed that more years since the mid 1990s have had high peak discharges despite having relatively less annual rain. The study also presents the hydrologic model calibration and validation results over the Nzoia basin. The spatiotemporal variability of the water cycle components were quantified using a hydrologic model, with in-situ and multi-satellite remote sensing datasets. The model is calibrated using daily observed discharge data for the period between 1985 and 1999, for which model performance is estimated with a Nash Sutcliffe Efficiency (NSCE) of 0.87 and 0.23% bias. The model validation showed an error metrics with NSCE of 0.65 and 1.04% bias. Moreover, the hydrologic capability of satellite precipitation (TRMM-3B42 V6) is evaluated. In terms of reconstruction of the water cycle components the spatial distribution and time series of modeling results for precipitation and runoff showed considerable agreement with the monthly model runoff estimates and gauge observations. Runoff values responded to precipitation events that occurred across the catchment during the wet season from March to early June.The spatially distributed model inputs, states, and outputs, were found to be useful for understanding the hydrologic behavior at the catchment scale. The monthly peak runoff is observed in the months of April, May and November. The analysis revealed a linear relationship between rainfall and runoff for both wet and dry seasons. Satellite precipitation forcing data showed the potential to be used not only for the investigation of water balance but also for addressing issues pertaining to sustainability of the resources at the catchment scale. Implementation of a flood prediction system can potentially help mitigate flood induced hazards. Such a system typically requires implementation and calibration of a hydrologic model using in-situ observations (e.g. rain gauges and stream gauges). Recently, satellite remote sensing data has emerged as a viable alternative or supplement to the in-situ observations due to its availability over vast ungauged regions. The focus of this study is to integrate the best available satellite products within a semi-distributed hydrologic model to characterize the spatial extent of flooding over sparsely-gauged or ungauged basins. A satellite remote sensing based approach is proposed to calibrate a hydrologic model, simulate the spatial extent of flooding, and evaluate the probability of detecting inundated areas. A raster-based semi-distributed hydrologic model, CREST, is implemented for the Nzoia basin, a sub-basin of Lake Victoria in Africa. MODIS Terra and ASTER-based raster flood inundation maps were produced over the region and used to benchmark the hydrologic model simulations of inundated areas. The analysis showed the value of integrating satellite data such as precipitation, land cover type, topography and other data products along with space based flood inundation extents as inputs for the hydrologic model. It is concluded that the quantification of flooding spatial extent through optical sensors can help to evaluate hydrologic models and hence potentially improve hydrologic prediction and flood management strategies in ungauged catchments.

Khan, Sadiq Ibrahim

2011-12-01

302

HBV genotypes and antiviral-resistant variants in HBV infected subjects in Northern Italy  

Microsoft Academic Search

HBV genotypes were investigated in sera\\/plasma from 97 HBV positive subjects. Genotype D was revealed in 80.4% followed by E in 6.2%. Genotypes A, B, and C were also found, as well as for the first time a new combination of HBV D and G genotypes. In a cohort of subjects of this population, the relationship with lamivudine and\\/or fam-

Maria Cristina Medici; Annalisa Aloisi; Monica Martinelli; Laura Anna Abelli; Francesca Casula; Pierpaolo Valcavi; Giuseppe Dettori; Carlo Chezzi

2006-01-01

303

Intercomparison and suitability of five Greenland topographic datasets for the purpose of hydrologic runoff modeling  

NASA Astrophysics Data System (ADS)

Rapid melting of the Greenland Ice Sheet (GrIS) and subsequent sea level rise has underscored the need for accurate modeling of hydrologic processes. Researchers rely on the accuracy of topography datasets for this purpose, especially in remote areas like Greenland where in situ validation data are difficult to acquire. A number of new remotely-sensed Digital Elevation Models (DEMs) have recently become available for Greenland, but a comparative study of their respective quality and suitability for hydrologic modeling has not been undertaken. We examine five such remotely-sensed DEMs acquired for proglacial and supraglacial ablation zones of Greenland, namely (1) WorldView stereo DEMs, (2) NASA GLISTIN-A experimental radar, (3) NASA/IceBridge Airborne Topographic Mapper (ATM), (4) Greenland Ice Mapping Project (GIMP) DEM, and (5) ASTER DEM. The quality, strengths and weaknesses of these DEMs for GrIS hydrologic modeling is assessed through intercomparison and in situ terrestrial lidar scanning data with precise RTK GPS control. Additionally, gridded bedrock (i.e. NASA/IceBridge Multichannel Coherent Radar Depth Sounder (MCoRDS); Bamber DEMs) and surface topography datasets are combined to create a hydraulic potentiometric surface for hydrologic modeling. Finally, the suitability of these combined topographic products for hydrologic modeling, characterization of GrIS meltwater runoff, and estimating sub- and/or englacial pathways is explored.

Pitcher, L. H.; Smith, L. C.; Rennermalm, A. K.; Chu, V. W.; Gleason, C. J.; Yang, K.; Finnegan, D. C.; LeWinter, A. L.; Moller, D.; Moustafa, S.

2012-12-01

304

Using dynamically downscaled GCM outputs in hydrological models: a case study from Tasmania, Australia  

Microsoft Academic Search

Modelling future runoff by running meteorological projections from global climate models (GCMs) directly through hydrological models presents considerable technical challenges, but promises several advantages over the so-called `perturbation method'. The Climate Futures for Tasmania project has projected water yield in Tasmania, Australia to 2100. This paper describes how the Climate Futures for Tasmania project used dynamically downscaled climate projections directly

J. Bennett; M. Grose; F. Ling; S. Corney; G. Holz; C. White; B. Graham; D. Post; N. Bindoff

2010-01-01

305

Using a Dynamic Hydrology Model To Predict Mosquito Abundances in Flood and Swamp Water  

Microsoft Academic Search

We modeled surface wetness at high resolution, using a dynamic hydrology model, to predict flood and swamp water mosquito abundances. Historical meteorologic data, as well as topographic, soil, and vegeta- tion data, were used to model surface wetness and identify potential fresh and swamp water breeding habi- tats in two northern New Jersey watersheds. Surface wetness was positively associated with

Jeffrey Shaman; Marc Stieglitz; Colin Stark; Sylvie Le Blancq; Mark Cane

2002-01-01

306

Integrated Hydrologic Models for Closing the Water Budget: Whitewater River Basin, Kansas  

Microsoft Academic Search

Groundwater and its recharge are unobserved and unmeasured components of the water cycle of a river basin. The objectives of this study were: 1) to evaluate the groundwater component of the water balance for the Whitewater River Basin using a 3-D saturated groundwater model, 2) to compare the groundwater model results with a fully integrated hydrologic model and, 3) to

P. Beeson; C. Duffy; E. Springer; S. Panday

2004-01-01

307

Calibration of a semi-distributed hydrologic model for streamflow estimation along a river system  

E-print Network

by the next generation radar (NEXRAD) network, high resolution digital elevation models (DEM), soil, land distributed data, and methods suitable for model development and calibration, the US National Weather Service-use and vegetation data can be integrated into an improved system for distributed hydrologic modeling that provides

Wagener, Thorsten

308

Using the SWAT model to improve process descriptions and define hydrologic partitioning in South Korea  

NASA Astrophysics Data System (ADS)

Watershed-scale modeling can be a valuable tool to aid in quantification of water quality and yield; however, several challenges remain. In many watersheds, it is difficult to adequately quantify hydrologic partitioning. Data scarcity is prevalent, accuracy of spatially distributed meteorology is difficult to quantify, forest encroachment and land use issues are common, and surface water and groundwater abstractions substantially modify watershed-based processes. Our objective is to assess the capability of the Soil and Water Assessment Tool (SWAT) model to capture event-based and long-term monsoonal rainfall-runoff processes in complex mountainous terrain. To accomplish this, we developed a unique quality-control, gap-filling algorithm for interpolation of high-frequency meteorological data. We used a novel multi-location, multi-optimization calibration technique to improve estimations of catchment-wide hydrologic partitioning. The interdisciplinary model was calibrated to a unique combination of statistical, hydrologic, and plant growth metrics. Our results indicate scale-dependent sensitivity of hydrologic partitioning and substantial influence of engineered features. The addition of hydrologic and plant growth objective functions identified the importance of culverts in catchment-wide flow distribution. While this study shows the challenges of applying the SWAT model to complex terrain and extreme environments; by incorporating anthropogenic features into modeling scenarios, we can enhance our understanding of the hydroecological impact.

Shope, C. L.; Maharjan, G. R.; Tenhunen, J.; Seo, B.; Kim, K.; Riley, J.; Arnhold, S.; Koellner, T.; Ok, Y. S.; Peiffer, S.; Kim, B.; Park, J.-H.; Huwe, B.

2014-02-01

309

Assessing impacts of hydropower schemes in upland rivers and sensitivity to hydrological change: new modelling tools for evaluating environmental flows  

NASA Astrophysics Data System (ADS)

Upland river systems provide a suite of critical ecosystem services, such as the provision of high quality downstream water supplies and the maintenance of in-stream habitats. Environmental legislation dictates that exploiting the hydro-power potential of such headwaters requires that the ecological status of in-stream habitats is maintained. This requires that decision makers have adequate scientific understanding of natural flow regimes, the nature of regulation impacts, and the sensitivity of managed systems to future change. This is often limited by a lack of adequate pre- regulation data. Here we present a new modelling tool that can be used in data sparse mountain river ecosystems to assess current impacts, evaluate sensitivity to future change and provide a basis for discussing the development of new adaptive management strategies. The HBV rainfall-runoff model was adapted to incorporate regulation components (reservoirs, water transfers), and applied to the heavily regulated River Lyon (391 km2), Scotland, UK. The Lyon has long been subjected to hydropower generation, which is supported by several river impoundments and a complex network of inter- and intra-catchment water transfers, and there are concerns that these are affecting high conservation status freshwater populations of Atlantic Salmon (Salmo salar). In the absence of adequate pre-regulation data, the model was used to characterise the natural flow regime, assess the regulation impacts, and explore sensitivities to hydrological changes in water management. Overall, changes following regulation in the Lyon include decreases in inter-and intra annual variability of all parameters of the flow regime in terms of magnitude, frequency, duration and timing that are important in various life stages of the Atlantic Salmon. Although these effects are most pronounced closest to the impoundments, the regulation affects the regime for a considerable distance downstream. Sensitivity tests showed that a more variable release regime, as opposed to changes in the efficiency of the present regulation regime, could be most beneficial for the ecological status of the Lyon. The simple, conceptual modelling approach presented here captures the dominant catchment and regulation processes well, especially at the time scale at which operation rules apply. Consequentially, it is data undemanding, flexible, widely applicable, and its results are easily communicated to stakeholders. Hence, it is providing a basis for assessing impacts on flow regimes and informing environmental flows in other (data sparse) regions with heavily regulated mountain river ecosystems.

Tetzlaff, D.; Geris, J.; Seibert, J.; Vis, M.; Soulsby, C.

2013-12-01

310

Evaluating and improving hydrologic processes in the community land model for integrated earth system modeling  

NASA Astrophysics Data System (ADS)

High climatic sensitivity and low anthropogenic influence make glacierized river basins important environments for examining hydrological and ecological response to global change. This paper synthesises findings from previous and ongoing research in glacierized Alpine and Arctic river basins (located in the French Pyrenees, New Zealand, Swedish Lapland and Svalbard), which adopts an interdisciplinary approach to investigate the climate-cryosphere-hydrology-ecology cascade. Data are used to advance hypotheses concerning the consequences of climate change/ variability on glacier river system hydrology and ecology. Aquatic ecosystems in high latitude and altitude environments are influenced strongly by cryospheric and hydrological processes due to links between atmospheric forcing, snowpack/ glacier mass-balance, river runoff, physico-chemistry and biota. In the current phase of global warming, many glaciers are retreating. Using downscaled regional climate projections as inputs to a distributed hydrological model for a study basin in the French Pyrenees (i.e. an environment at the contemporary limit of valley glaciation), we show how shrinking snow and ice-masses may alter space-time dynamics in basin runoff. Notably, the timing of peak snow- and ice-melt may shift; and the proportion of stream flow sourced from rainfall-runoff (cf. meltwater) may increase. Across our range of Alpine and Arctic study basins, we quantify observed links between relative water source contributions (% meltwater : % groundwater), physico-chemical habitat (e.g. water temperature, electrical conductivity, suspended sediment and channel stability) and benthic communities. At the site scale, results point towards increased community diversity (taxonomic and functional) as meltwater contributions decline and physico-chemical habitat becomes less harsh. However, basin-scale biodiversity may be reduced due to less spatio-temporal heterogeneity in water source contributions and habitats, and the extinction of cold stenothermic specialists. Similar integrated, long-term research into hydroecological connections in other glacierized river basins is vital: (1) to enable robust projections of stream hydrology (water source contributions and physico-chemical habitat) and ecological response under scenarios of future climate/ variability, and (2) to develop conservation strategies for these fragile Alpine and Arctic freshwater ecosystems.

Hannah, D. M.; Khamis, K.; Blaen, P. J.; Hainie, S.; Mellor, C.; Brown, L. E.; Milner, A. M.

2011-12-01

311

Inverse modeling for field-scale hydrologic and transport parameters of fractured basalt  

SciTech Connect

A large-scale test of infiltration into a thick sequence Of fractured Snake River Plain basalts was performed during the summer of 1994 on the Idaho National Engineering Laboratory. Monitoring of moisture and tracer movement during this test provided a set of quantitative measurements from which to obtain a field-scale hydrologic description of the fractured basalts. An inverse modeling study using these quantitative measurements was performed to obtain the representative hydrologic description. This report describes the results of the inverse modeling study and includes the background and motivation for conducting the infiltration test; a brief overview of the infiltration test; descriptions of the calibration targets chosen for the simulation study, the simulation model, and the model implementation; and the simulation results with comparisons to hydrologic and tracer breakthrough data obtained from the infiltration test.

Magnuson, S.O.

1995-12-01

312

Identifying Droughts by Modeling the Hydrologic and Ecologic Responses in the Medjerda River Basin, Tunisia  

NASA Astrophysics Data System (ADS)

Drought brings severe damage to water and agricultural resources, and both of hydrological and ecological responses are important for understanding droughts. However, the ecological contributions to drought characteristics at the basin scale have not been quantified. To address this issue, we developed an eco-hydrological model that can calculate vegetation dynamics as a diagnostic valuable in a distributed-hydrological modeling framework and identified different drought types in the Medjerda River Basin where drought is a predominant issue. From the inputs and outputs of the model, we calculate drought indices for different drought types. The model shows reliable accuracy in reproducing the observed river discharge and the satellite observed leaf area index in the long-term (19-year) simulation. Moreover, the drought index calculated from model estimated annual peak of leaf area index is well correlated (correlation coefficient; r = 0.89; see Figure) with drought index from nationwide annual crop production, which show the modeled leaf area index has enough capacity to reproducing agricultural droughts that can be related with historical food shortage on 1988-1989 and 1993-1995. Our model can estimate vegetation dynamics and water cycle simultaneously in the enough accuracy to analyze the basin-scale agricultural and hydrological droughts separately. We clarify that vegetation dynamics has quicker response to meteorological droughts than river discharge and groundwater dynamics in Medjerda River Basin because vegetation dynamics is sensitive to soil moisture in surface layers while soil moisture in deeper layers strongly contributes to stream flow and depth of groundwater level. Therefore, historical agricultural droughts predominantly occurred prior to hydrological droughts and in the 1988-1989 drought, the hydrological drought lasted much longer even after crop production recovered. Standardized anomaly index (SA) for estimated annual maximum leaf area index (green line) from model and observed annual crop production in Tunisia (orange line).

Sawada, Y.; Koike, T.; Jaranilla-sanchez, P. A.

2013-12-01

313

Assessment of NASA's Physiographic and Meteorological Datasets as Input to HSPF and SWAT Hydrological Models  

NASA Technical Reports Server (NTRS)

This paper documents the use of simulated Moderate Resolution Imaging Spectroradiometer land use/land cover (MODIS-LULC), NASA-LIS generated precipitation and evapo-transpiration (ET), and Shuttle Radar Topography Mission (SRTM) datasets (in conjunction with standard land use, topographical and meteorological datasets) as input to hydrological models routinely used by the watershed hydrology modeling community. The study is focused in coastal watersheds in the Mississippi Gulf Coast although one of the test cases focuses in an inland watershed located in northeastern State of Mississippi, USA. The decision support tools (DSTs) into which the NASA datasets were assimilated were the Soil Water & Assessment Tool (SWAT) and the Hydrological Simulation Program FORTRAN (HSPF). These DSTs are endorsed by several US government agencies (EPA, FEMA, USGS) for water resources management strategies. These models use physiographic and meteorological data extensively. Precipitation gages and USGS gage stations in the region were used to calibrate several HSPF and SWAT model applications. Land use and topographical datasets were swapped to assess model output sensitivities. NASA-LIS meteorological data were introduced in the calibrated model applications for simulation of watershed hydrology for a time period in which no weather data were available (1997-2006). The performance of the NASA datasets in the context of hydrological modeling was assessed through comparison of measured and model-simulated hydrographs. Overall, NASA datasets were as useful as standard land use, topographical , and meteorological datasets. Moreover, NASA datasets were used for performing analyses that the standard datasets could not made possible, e.g., introduction of land use dynamics into hydrological simulations

Alacron, Vladimir J.; Nigro, Joseph D.; McAnally, William H.; OHara, Charles G.; Engman, Edwin Ted; Toll, David

2011-01-01

314

A digital hydrological model of high, cold alpine areas and its application  

NASA Astrophysics Data System (ADS)

In a watershed of high cold alpine areas mainly supplemented with melted snow, glacier water and rainfall, the spatial distribution of runoff is extremely uneven over the whole region. With the development of DEMs and the advances on GIS technology, digital hydrology was developed, digital hydrology construction was enriched, and powerful technical support was provided to the discipline in recent years. Models can preferably reappear represent real hydrology processes; moreover the selection of partial parameters has the persuasive power to overcome the influences of artificial and subjective factors. Utilizing the technology of remote sensing (RS) and GIS the space distribution of underlying information, intermediate-state information and cover information of basin snow cover each time RS images are acquired and portrayed in the study of basin hydrologic processes. Based on the Xinanjiang Model, a digital hydrological model which suits streams mainly supplemented with melted snow, glacial water and rainfall in alpine regions was established. The model was applied to simulate snowmelt-runoff in 2005.The results were good and reflect the actual changing trend of in runoff. The deterministic coefficient of forecast projections is 0.812.

Mu, Zhenxia; Jiang, Huifang; Peng, Liang; He, Ying

2010-11-01

315

SEHR-ECHO v1.0: a Spatially Explicit Hydrologic Response model for ecohydrologic applications  

NASA Astrophysics Data System (ADS)

This paper presents the Spatially Explicit Hydrologic Response (SEHR) model developed at the Laboratory of Ecohydrology of the Ecole Polytechnique Fédérale de Lausanne for the simulation of hydrological processes at the catchment scale. The key concept of the model is the formulation of water transport by geomorphologic travel time distributions through gravity-driven transitions among geomorphic states: the mobilization of water (and possibly dissolved solutes) is simulated at the subcatchment scale and the resulting responses are convolved with the travel paths distribution within the river network to obtain the hydrologic response at the catchment outlet. The model thus breaks down the complexity of the hydrologic response into an explicit geomorphological combination of dominant spatial patterns of precipitation input and of hydrologic process controls. Nonstationarity and nonlinearity effects are tackled through soil moisture dynamics in the active soil layer. We present here the basic model set-up for precipitation-runoff simulation and a detailed discussion of its parameter estimation and of its performance for the Dischma River (Switzerland), a snow-dominated catchment with a small glacier cover.

Schaefli, B.; Nicótina, L.; Imfeld, C.; Da Ronco, P.; Bertuzzo, E.; Rinaldo, A.

2014-11-01

316

Towards a regional climate model coupled to a comprehensive hydrological model  

NASA Astrophysics Data System (ADS)

When planing new ground water abstractions wells, building areas, roads or other land use activities information about expected future groundwater table location for the lifetime of the construction may be critical. The life time of an abstraction well can be expected to be more than 50 years, while if for buildings may be up to 100 years or more. The construction of an abstraction well is expensive and it is important to know if clean groundwater is available for its expected life time. The future groundwater table is depending on the future climate. With climate change the hydrology is expected to change as well. Traditionally, this assessment has been done by driving hydrological models with output from a climate model. In this way feedback between the groundwater hydrology and the climate is neglected. Neglecting this feedback can lead to imprecise or wrong results. The goal of this work is to couple the regional climate model HIRHAM (Christensen et al. 2006) to the hydrological model MIKE SHE (Graham and Butts, 2006). The coupling exploits the new OpenMI technology that provides a standardized interface to define, describe and transfer data on a time step basis between software components that run simultaneously (Gregersen et al., 2007). HIRHAM runs on a UNIX platform whereas MIKE SHE and OpenMI are under WINDOWS. Therefore the first critical task has been to develop an effective communication link between the platforms. The first step towards assessing the coupled models performance are addressed by looking at simulated land-surface atmosphere feedback through variables such as evapotranspiration, sensible heat flux and soil moisture content. Christensen, O.B., Drews, M., Christensen, J.H., Dethloff, K., Ketelsen, K., Hebestadt, I. and Rinke, A. (2006) The HIRHAM Regional Climate Model. Version 5; DMI Scientific Report 0617. Danish Meteorological Institute. Graham, D.N. and Butts, M.B. (2005) Flexible, integrated watershed modelling with MIKE SHE, In Watershed Models, (Eds. V.P. Singh & D.K. Frevert) CRC Press. Pages 245-272, ISBN: 0849336090. Gregersen, J.B., Gijsbers, P.J.A. and Westen, S.J.P. (2007) OpenMI: Open modelling interface. Journal of Hydroinformatics, 09.3, 175191. doi: 10.2166/hydro.2007.023.

Rasmussen, S. H.; Drews, M.; Christensen, J. H.; Butts, M. B.; Jensen, K. H.; Refsgaard, J.; Hydrological ModellingAssessing Climate Change Impacts At Different Scales (Hyacints)

2010-12-01

317

Estimation of climate change impacts on river flow and catchment hydrological connectivity incorporating uncertainty from multiple climate models, stochastic downscaling and hydrological model parameterisation error sources  

NASA Astrophysics Data System (ADS)

When estimating climate change impacts, there are many sources of uncertainty which must be considered. The main sources of uncertainty arise from the structure and parameterisation of physically based simulation models, downscaling methods, stochastic realisations of future weather time series and the underlying emission scenarios. This work focuses on the uncertainties resulting from the use of multiple climate models and the joint impact of the stochastic realisations of future weather time series from a weather generator, EARWIG, and from parameter estimation uncertainty of a hydrological model, CAS-Hydro. These tools have been applied to the River Rye, Yorkshire. A suite of model parameter sets and weather realisations have been used to project likely changes to the hydrological functioning under climate change. Results are presented on the projected changes in flow duration curves and the potential changes in the hydrological connectivity by overland flow within the catchment. The statistical sensitivity of the impact predictions to these sources of uncertainty and the use of a multi-model ensemble to enable the production of probabilistic estimates of change is assessed. These estimates of potential changes in flow can then be used to inform the adaptation of water resources design and management.

Reaney, S. M.; Fowler, H. J.

2008-12-01

318

Inhibition of hepatitis B virus (HBV) by LNA-mediated nuclear interference with HBV DNA transcription  

SciTech Connect

Highlights: {yields} LNA-modified oligonucleotides can pass through the plasma membrane of cultured cells even without using transfection machinery. {yields} LNA-modified oligonucleotides passed efficiently across the cell membrane, and lipid-coating facilitated translocation from the cytoplasm to the nucleus. {yields} LNA-oligonucleotide designed to target nuclear HBV DNA efficiently suppresses HBV replication and transcription in cultured hepatic cells. -- Abstract: Silencing target genes with small regulatory RNAs is widely used to investigate gene function and therapeutic drug development. Recently, triplex-based approaches have provided another attractive means to achieve targeted gene regulation and gene manipulation at the molecular and cellular levels. Nuclear entry of oligonucleotides and enhancement of their affinity to the DNA targets are key points of such approaches. In this study, we developed lipid-based transport of a locked-nucleic-acid (LNA)-modified oligonucleotide for hepatitis B virus (HBV) DNA interference in human hepatocytes expressing HBV genomic DNA. In these cells, the LNA-modified oligonucleotides passed efficiently across the cell membrane, and lipid-coating facilitated translocation from the cytoplasm to the nucleus. The oligonucleotide specifically targeting HBV DNA clearly interfered with HBV DNA transcription as shown by a block in pregenomic RNA (pgRNA) production. The HBV DNA-targeted oligonucleotide suppressed HBV DNA replication and HBV protein production more efficiently than small interfering RNAs directed to the pgRNA. These results demonstrate that fusion with lipid can carry LNA-modified oligonucleotides to the nucleus where they regulate gene expression. Interfering with HBV DNA transcription by LNA-modified oligonucleotides has strong potential as a new strategy for HBV inhibition.

Sun, Zhen [The State Key Laboratory of Genetic Engineering and The MOE Key Laboratory of Contemporary Anthropology, School of Life Science, Fudan University, Shanghai 200433 (China) [The State Key Laboratory of Genetic Engineering and The MOE Key Laboratory of Contemporary Anthropology, School of Life Science, Fudan University, Shanghai 200433 (China); Department of Biochemistry and Molecular Biology, Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058 (China); Xiang, Wenqing; Guo, Yajuan [Department of Biochemistry and Molecular Biology, Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058 (China)] [Department of Biochemistry and Molecular Biology, Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058 (China); Chen, Zhi [The State Key Laboratory for Infectious Disease, Institute of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China)] [The State Key Laboratory for Infectious Disease, Institute of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China); Liu, Wei, E-mail: liuwei666@zju.edu.cn [Department of Biochemistry and Molecular Biology, Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058 (China)] [Department of Biochemistry and Molecular Biology, Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058 (China); Lu, Daru, E-mail: drlu@fudan.edu.cn [The State Key Laboratory of Genetic Engineering and The MOE Key Laboratory of Contemporary Anthropology, School of Life Science, Fudan University, Shanghai 200433 (China)] [The State Key Laboratory of Genetic Engineering and The MOE Key Laboratory of Contemporary Anthropology, School of Life Science, Fudan University, Shanghai 200433 (China)

2011-06-10

319

Are Hydrologic Model Parameters Scalable? An Investigation into the Catchment Connectivity Model  

NASA Astrophysics Data System (ADS)

Rainfall-runoff models are often able to match streamflow dynamics (following calibration), while at the same time failing to produce simulations that are consistent with internal watershed processes. This well-recognized fact led to the development of the recently introduced Catchment Connectivity Model (CCM). Developed following a dominant process conceptualization based on hillslope hydrologic connectivity at the Tenderfoot Creek Experimental Forest (TCEF; Montana, USA), the three-parameter CCM is a spatially explicit model structure. The CCM has been validated against extensive field observations of hillslope hydrologic connectivity (an internal process simulated by the model) to demonstrate its internal consistency, in addition to a traditional assessment to the external streamflow dynamics. In this study, we sought to examine the scalability of the CCM parameters. Specifically, we explored whether the catchment scale model parameterization was transferrable to nested, sub-catchments. Model assessment was informed by, and tested against, results from recent incremental (~200m stream reaches) discharge measurements at TCEF. This investigation allowed us to develop a more in-depth understanding of the model structure, its flexibility, its transferability, and its scalability.

Hayes, K. D.; Smith, T. J.; Jencso, K. G.; McGlynn, B. L.; Marshall, L. A.; Bergstrom, A.

2013-12-01

320

Moving university hydrology education forward with geoinformatics, data and modeling approaches  

NASA Astrophysics Data System (ADS)

In this opinion paper, we review recent literature related to data and modeling driven instruction in hydrology, and present our findings from surveying the hydrology education community in the United States. This paper presents an argument that that Data and Modeling Driven Geoscience Cybereducation (DMDGC) approaches are valuable for teaching the conceptual and applied aspects of hydrology, as a part of the broader effort to improve Science, Technology, Engineering, and Mathematics (STEM) education at the university level. The authors have undertaken a series of surveys and a workshop involving the community of university hydrology educators to determine the state of the practice of DMDGC approaches to hydrology. We identify the most common tools and approaches currently utilized, quantify the extent of the adoption of DMDGC approaches in the university hydrology classroom, and explain the community's views on the challenges and barriers preventing DMDGC approaches from wider use. DMDGC approaches are currently emphasized at the graduate level of the curriculum, and only the most basic modeling and visualization tools are in widespread use. The community identifies the greatest barriers to greater adoption as a lack of access to easily adoptable curriculum materials and a lack of time and training to learn constantly changing tools and methods. The community's current consensus is that DMDGC approaches should emphasize conceptual learning, and should be used to complement rather than replace lecture-based pedagogies. Inadequate online material-publication and sharing systems, and a lack of incentives for faculty to develop and publish materials via such systems, is also identified as a challenge. Based on these findings, we suggest that a number of steps should be taken by the community to develop the potential of DMDGC in university hydrology education, including formal development and assessment of curriculum materials integrating lecture-format and DMDGC approaches, incentivizing the publication by faculty of excellent DMDGC curriculum materials, and implementing the publication and dissemination cyberinfrastructure necessary to support the unique DMDGC digital curriculum materials.

Merwade, V.; Ruddell, B. L.

2012-02-01

321

Moving university hydrology education forward with community-based geoinformatics, data and modeling resources  

NASA Astrophysics Data System (ADS)

In this opinion paper, we review recent literature related to data and modeling driven instruction in hydrology, and present our findings from surveying the hydrology education community in the United States. This paper presents an argument that that data and modeling driven geoscience cybereducation (DMDGC) approaches are essential for teaching the conceptual and applied aspects of hydrology, as a part of the broader effort to improve science, technology, engineering, and mathematics (STEM) education at the university level. The authors have undertaken a series of surveys and a workshop involving university hydrology educators to determine the state of the practice of DMDGC approaches to hydrology. We identify the most common tools and approaches currently utilized, quantify the extent of the adoption of DMDGC approaches in the university hydrology classroom, and explain the community's views on the challenges and barriers preventing DMDGC approaches from wider use. DMDGC approaches are currently emphasized at the graduate level of the curriculum, and only the most basic modeling and visualization tools are in widespread use. The community identifies the greatest barriers to greater adoption as a lack of access to easily adoptable curriculum materials and a lack of time and training to learn constantly changing tools and methods. The community's current consensus is that DMDGC approaches should emphasize conceptual learning, and should be used to complement rather than replace lecture-based pedagogies. Inadequate online material publication and sharing systems, and a lack of incentives for faculty to develop and publish materials via such systems, is also identified as a challenge. Based on these findings, we suggest that a number of steps should be taken by the community to develop the potential of DMDGC in university hydrology education, including formal development and assessment of curriculum materials, integrating lecture-format and DMDGC approaches, incentivizing the publication by faculty of excellent DMDGC curriculum materials, and implementing the publication and dissemination cyberinfrastructure necessary to support the unique DMDGC digital curriculum materials.

Merwade, V.; Ruddell, B. L.

2012-08-01

322

Application of a Simple Raster-Based Hydrological Model for Streamflow Prediction in a Humid Catchment with Polder Systems  

Microsoft Academic Search

The hydrological processes are controlled by many factors such as topography, soil, climate and land management practices.\\u000a These factors have been included in most hydrological models. This study develops a raster-based distributed hydrological\\u000a model for catchment runoff simulation integrating flood polders regulation. The overland flow and channel flow are calculated\\u000a by kinematic wave equations. A simple bucket method is used

Guangju Zhao; Georg Hörmann; Nicola Fohrer; Junfeng Gao; Hengpeng Li; Peng Tian

2011-01-01

323

Brief summary of LADHS: Los Alamos distributed hydrologic modeling system.  

SciTech Connect

This report describes the current state of the fourth Thrust Area of the NSF Science and Technology Center for the Sustainability of Semi-Arid Hydrology and Riparian Areas (SAHRA). Sustainability of semi-arid regions has become a serious political and scientific concern. Increasing population has added stress to the water supply and other natural resources, notably, underground aquifers. Recent controversies in the Rio Grande Basin involving the competing interests of endangered species and humans for water have highlighted the delicate balance of biologically diverse southwestern riparian areas. Potentially, the warming climate may intensify summer storms and affect the amount and timing of snow melt, the largest renewable source of water in the southwest. It is, therefore, of great political, social and scientific interest to determine ways in which human activities can coexist with healthy riparian areas and a plentiful, clean water supply over the long run. An understanding of how all of these processes interrelate would allow regional decision-makers to consider a wide range of options and thereby develop useful plans for meeting societal needs. To make the best use of limited fresh water resources, decision makers must be able to make predictions about the entire hydrologic cycle, which is a complex combination of physical, chemical, and biological processes. Only then could they explore the potential effects of increased water use and of changes in the regional climate. The important processes in the hydrologic cycle include rainfall, snowmelt, storms, runoff, and flow in ephemeral streams, rivers, and underground aquifers. Riparian communities and evaporation play key roles in reducing the available water.

Murray, R. E. (Regan E.); Winter, C. L. (C. Larrabee); Springer, E. P.; Costigan, K. R. (Keeley R.); Tseng, P. H. (Peng-Hsiang)

2001-01-01

324

Reducing hydrologic model uncertainty in monthly streamflow predictions using multimodel combination  

NASA Astrophysics Data System (ADS)

Model errors are inevitable in any prediction exercise. One approach that is currently gaining attention in reducing model errors is by combining multiple models to develop improved predictions. The rationale behind this approach primarily lies on the premise that optimal weights could be derived for each model so that the developed multimodel predictions will result in improved predictions. A new dynamic approach (MM-1) to combine multiple hydrological models by evaluating their performance/skill contingent on the predictor state is proposed. We combine two hydrological models, "abcd" model and variable infiltration capacity (VIC) model, to develop multimodel streamflow predictions. To quantify precisely under what conditions the multimodel combination results in improved predictions, we compare multimodel scheme MM-1 with optimal model combination scheme (MM-O) by employing them in predicting the streamflow generated from a known hydrologic model (abcd model orVICmodel) with heteroscedastic error variance as well as from a hydrologic model that exhibits different structure than that of the candidate models (i.e., "abcd" model or VIC model). Results from the study show that streamflow estimated from single models performed better than multimodels under almost no measurement error. However, under increased measurement errors and model structural misspecification, both multimodel schemes (MM-1 and MM-O) consistently performed better than the single model prediction. Overall, MM-1 performs better than MM-O in predicting the monthly flow values as well as in predicting extreme monthly flows. Comparison of the weights obtained from each candidate model reveals that as measurement errors increase, MM-1 assigns weights equally for all the models, whereas MM-O assigns higher weights for always the best-performing candidate model under the calibration period. Applying the multimodel algorithms for predicting streamflows over four different sites revealed that MM-1 performs better than all single models and optimal model combination scheme, MM-O, in predicting the monthly flows as well as the flows during wetter months.

Li, Weihua; Sankarasubramanian, A.

2012-12-01

325

Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling  

USGS Publications Warehouse

Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based/statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling. ?? 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA.

Brakebill, J.W.; Wolock, D.M.; Terziotti, S.E.

2011-01-01

326

The implementation and validation of improved land-surface hydrology in an atmospheric general circulation model  

NASA Technical Reports Server (NTRS)

New land-surface hydrologic parameterizations are implemented into the NASA Goddard Institute for Space Studies (GISS) General Circulation Model (GCM). These parameterizations are: 1) runoff and evapotranspiration functions that include the effects of subgrid-scale spatial variability and use physically based equations of hydrologic flux at the soil surface and 2) a realistic soil moisture diffusion scheme for the movement of water and root sink in the soil column. A one-dimensional climate model with a complete hydrologic cycle is used to screen the basic sensitivities of the hydrological parameterizations before implementation into the full three-dimensional GCM. Results of the final simulation with the GISS GCM and the new land-surface hydrology indicate that the runoff rate, especially in the tropics, is significantly improved. As a result, the remaining components of the heat and moisture balance show similar improvements when compared to observations. The validation of model results is carried from the large global (ocean and land-surface) scale to the zonal, continental, and finally the regional river basin scales.

Johnson, Kevin D.; Entekhabi, Dara; Eagleson, Peter S.

1993-01-01

327

The implementation and validation of improved landsurface hydrology in an atmospheric general circulation model  

NASA Technical Reports Server (NTRS)

Landsurface hydrological parameterizations are implemented in the NASA Goddard Institute for Space Studies (GISS) General Circulation Model (GCM). These parameterizations are: (1) runoff and evapotranspiration functions that include the effects of subgrid scale spatial variability and use physically based equations of hydrologic flux at the soil surface, and (2) a realistic soil moisture diffusion scheme for the movement of water in the soil column. A one dimensional climate model with a complete hydrologic cycle is used to screen the basic sensitivities of the hydrological parameterizations before implementation into the full three dimensional GCM. Results of the final simulation with the GISS GCM and the new landsurface hydrology indicate that the runoff rate, especially in the tropics is significantly improved. As a result, the remaining components of the heat and moisture balance show comparable improvements when compared to observations. The validation of model results is carried from the large global (ocean and landsurface) scale, to the zonal, continental, and finally the finer river basin scales.

Johnson, Kevin D.; Entekhabi, Dara; Eagleson, Peter S.

1991-01-01

328

Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling1  

PubMed Central

Abstract Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based/statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling. PMID:22457575

Brakebill, JW; Wolock, DM; Terziotti, SE

2011-01-01

329

GIS/RS-based Integrated Eco-hydrologic Modeling in the East River Basin, South China  

NASA Astrophysics Data System (ADS)

Land use/cover change (LUCC) has significantly altered the hydrologic system in the East River (Dongjiang) Basin. Quantitative modeling of hydrologic impacts of LUCC is of great importance for water supply, drought monitoring and integrated water resources management. An integrated eco-hydrologic modeling system of Distributed Monthly Water Balance Model (DMWBM), Surface Energy Balance System (SEBS) was developed with aid of GIS/RS to quantify LUCC, to conduct physically-based ET (evapotranspiration) mapping and to predict hydrologic impacts of LUCC. To begin with, in order to evaluate LUCC, understand implications of LUCC and provide boundary condition for the integrated eco-hydrologic modeling, firstly the long-term vegetation dynamics was investigated based on Normalized Difference Vegetation Index (NDVI) data, and then LUCC was analyzed with post-classification methods and finally LUCC prediction was conducted based on Markov chain model. The results demonstrate that the vegetation activities decreased significantly in summer over the years. Moreover, there were significant changes in land use/cover over the past two decades. Particularly there was a sharp increase of urban and built-up area and a significant decrease of grassland and cropland. All these indicate that human activities are intensive in the East River Basin and provide valuable information for constructing scenarios for studying hydrologic impacts of LUCC. The physically-remote-sensing-based Surface Energy Balance System (SEBS) was employed to estimate areal actual ET for a large area rather than traditional point measurements . The SEBS was enhanced for application in complex vegetated area. Then the inter-comparison with complimentary ET model and distributed monthly water balance model was made to validate the enhanced SEBS (ESEBS). The application and test of ESEBS show that it has a good accuracy both monthly and annually and can be effectively applied in the East River Basin. The results of ET mapping based on ESEBS demonstrate that actual ET in the East River Basin decreases significantly in the last two decades, which is probably caused by decrease of sunshine duration. In order to effectively simulate hydrologic impact of LUCC, an integrated model of ESEBS and distributed monthly water balance model has been developed in this study. The model is capable of considering basin terrain and the spatial distribution of precipitation and soil moisture. Particularly, the model is unique in accounting for spatial and temporal variations of vegetation cover and ET, which provides a powerful tool for studying the hydrologic impacts of LUCC. The model was applied to simulate the monthly runoff for the period of 1980-1994 for model calibration and for the period of 1995-2000 for validation. The calibration and validation results show that the newly integrated model is suitable for simulating monthly runoff and studying hydrologic impacts ofLUCC in the East River Basin. Finally, the newly integrated model was firstly applied to analyze the relationship of land use and hydrologic regimes based on the land use maps in 1980 and 2000. Then the newly integrated model was applied to simulate the potential impacts of land use change on hydrologic regimes in the East River Basin under a series of hypothetical scenarios. The results show that ET has a positive relationship with Leaf Area Index (LAI) while runoff has a negative relationship with LAI in the same climatic zone, which can be elaborated by surface energy balance and water balance equation. Specifically, on an annual basis, ET of forest scenarios is larger than that of grassland or cropland scenarios. On the contrary, runoff of forest scenarios is less than that of grassland or cropland scenarios. On a monthly basis, for most of the scenarios, particularly the grassland and cropland scenarios, the most significant changes occurred in the rainy season. The results indicate that deforestation would cause increase of runoff and decrease of ET on an annual basis in the East River Basin. On a monthly basis, de

Wang, Kai

330

Improving land-surface model hydrology: Is an explicit aquifer model better than a deeper soil profile?  

E-print Network

variation in terrestrial water storage; and (3) a lumped, unconfined aquifer model coupled to the shallowImproving land-surface model hydrology: Is an explicit aquifer model better than a deeper soil representation of an aquifer within a land-surface model (LSM) decreases the dependence of model performance

Yang, Zong-Liang

331

A Integrated Approach to Modelling Hydrology and Water Quality in Glacierized Catchments  

Microsoft Academic Search

The results are summarized of an integrated investigation of glacier geometry, ablation patterns, water balance, meltwater routing, hydrochemistry and suspended sediment yield. The ultimate objective is to evaluate the assumptions of lumped, two-component mixing models as descriptors of glacier hydrology, and to develop a semi-distributed physically based model as an alternative. The results of the study demonstrate that a reconstruction

Keith Richards; Martin Sharp; Neil Arnold; Angela Gurnell; Michael Clark; Martin Tranter; Peter Nienow; Giles Brown; Ian Willis; Wendy Lawson

1996-01-01

332

Hydrological modeling of the Martian crust with application to the pressurization of aquifers  

Microsoft Academic Search

(1) We develop a hydrological model of the Martian crust, including both ancient heavily cratered terrains and younger basaltic and sedimentary terrains. The porosity, permeability, and compressibility are represented as interdependent functions of the effective stress state of the aquifer, as determined by the combination of the lithostatic pressure and the fluid pore pressure. In the megaregolith aquifer model, the

Jeffrey C. Hanna; Roger J. Phillips

2005-01-01

333

Hydrological modeling of the Martian crust with application to the pressurization of aquifers  

Microsoft Academic Search

We develop a hydrological model of the Martian crust, including both ancient heavily cratered terrains and younger basaltic and sedimentary terrains. The porosity, permeability, and compressibility are represented as interdependent functions of the effective stress state of the aquifer, as determined by the combination of the lithostatic pressure and the fluid pore pressure. In the megaregolith aquifer model, the crust

Jeffrey C. Hanna; Roger J. Phillips

2005-01-01

334

Explicit simulations of stream networks to guide hydrological modelling in ungauged basins  

NASA Astrophysics Data System (ADS)

Rainfall-runoff modelling in ungauged basins is still one of the greatest challenges in hydrological research. The lack of discharge data necessitates the establishment of new innovative approaches to guide hydrological modelling in ungauged basins. Besides the transfer of calibrated parameters from similar gauged catchments, the application of distributed data as a hydrological response in addition to discharge seems to be promising. A new approach to guide hydrological modelling based on explicit simulation of the spatial stream network was tested in four different catchments in Germany. In a first step we used a simplified version of the process-based model Hill-Vi together with regional climate normals to simulate stream networks. The calculation of gravity driven lateral subsurface and groundwater flow is used to identify patterns of stream cells, which were compared to reference stream networks and their degree of spatial agreement was evaluated. Significant differences between good and poor simulations could be distinguished and the corresponding parameter sets relate well with the hydrogeological properties of the catchments. The optimized parameters were subsequently used to simulate daily discharge using an observed time series of precipitation and air temperature. The performance was evaluated against observed discharge and water balance. This approach shows some promising results but also some limitations. Although the model's parsimonious model structure could be further improved regarding discharge recession and evapotranspiration, the performance was similar to regionalisation methods. Stream network modelling, which has minimal data requirements, seems to be a reasonable alternative for model development and parameter evaluation in ungauged basins.

Stoll, S.; Weiler, M.

2010-08-01

335

Stochastic Residual-Error Analysis For Estimating Hydrologic Model Predictive Uncertainty  

EPA Science Inventory

A hybrid time series-nonparametric sampling approach, referred to herein as semiparametric, is presented for the estimation of model predictive uncertainty. The methodology is a two-step procedure whereby a distributed hydrologic model is first calibrated, then followed by brute ...

336

HYDROLOGIC MODELING OF AN EASTERN PENNSYLVANIA WATERSHED WITH NEXRAD AND RAIN GAUGE DATA  

EPA Science Inventory

This paper applies the Soil Water Assessment Tool (SWAT) to model the hydrology in the Pocono Creek watershed located in Monroe County, Pa. The calibrated model will be used in a subsequent study to examine the impact of population growth and rapid urbanization in the watershed o...

337

A LAND-SURFACE HYDROLOGY PARAMETERIZATION WITH SUBGRID VARIABILITY FOR GENERAL CIRCULATION MODELS  

EPA Science Inventory

Most of the existing generation of general circulation models (GCMs) use so-called bucket algorithms to represent land-surface hydrology. iosphere-atmosphere models that include the transfer of energy, mass, and momentum between the atmosphere and the land surface are a recent al...

338

Combined use of point rain gauges, radar, microwave link and level measurements in urban hydrological modelling  

Microsoft Academic Search

A methodology has been developed for the combined exploitation of the information content in several different types of rainfall and hydrological measurements. The methodology is based on simple rain plane and runoff models that are incorporated into a stochastic state–space model approach. State estimation is done using the extended Kalman filter in combination with a maximum likelihood estimation criterion and

Morten Grum; Stefan Kraemer; Hans-Reinhard Verworn; Axel Redder

2005-01-01

339

ORIGINAL ARTICLE Integration of hydrologic and water allocation models in basin-  

E-print Network

studies. This work presents an integrated modeling approach by linking Soil and Water Assessment ToolORIGINAL ARTICLE Integration of hydrologic and water allocation models in basin- scale water of climate and cropping pattern changes on agri- cultural and hydroenergy production in the Karkheh River

340

Investigation of Hydrological Variability in West Africa Using Land Surface Models.  

NASA Astrophysics Data System (ADS)

The availability of freshwater is a particularly important issue in Africa where large portions of the continent are arid or semiarid and climate is highly variable. Sustainable water resource management requires the assessment of hydrological variability in response to nature climate fluctuation. In this study, a land surface model, the Integrated Biosphere Simulator (IBIS), and a hydrological routing model, the Hydrological Routing Algorithm (HYDRA), are used to investigate the hydrological variability in two large basins, the Lake Chad basin (LCB) and the Niger River basin (NRB), located in West Africa, over the period from 1950 to 1995. The IBIS land surface hydrological module was calibrated and validated for arid and semiarid Africa, and major enhancements were made to the module, including the development of a dynamic root water-extraction formulation, the incorporation of a Green-Ampt infiltration parameterization, and modification to the prescribed root distribution, the runoff module, and weather generator. The results show that the hydrology in this area is highly variable over time and space. The coefficient of variance (CV) of annual rainfall ranges from 10%-15% in the southern portions of the basins to 30%-40% in the northern portions. The annual evapotranspiration (ET) varies with a slightly lower CV compared to the rainfall, but the runoff is extremely sensitive to the rainfall fluctuation, particularly in the central portions of the basins (8°-13°N in LCB and 12°-16°N in NRB) where the CVs in runoff are as high as 100%-200%. The annual river discharge varies largely in concert with the rainfall fluctuation, with the CV being 37% in LCB and 23%-63% in NRB. In terms of the whole basin, the relative hydrologic variability (rainfall, evapotranspiration, runoff, and river discharge) is significantly higher in the dry period than in the wet period, and the interannual variability in runoff is more than twice as high as compared to rainfall or ET.

Li, K. Y.; Coe, M. T.; Ramankutty, N.

2005-08-01

341

eWaterCycle: Developing a hyper resolution global hydrological model  

NASA Astrophysics Data System (ADS)

The development of a high resolution global hydrological model has recently been put forward as Grand Challenge for the hydrological community (Wood et al., 2011). The eWaterCycle project aims at developing a high resolution global hydrological model allowing for a better representation of the effects of spatial heterogeneity in topography, soil, and vegetation on hydrological dynamics. The original version of the global hydrological model PCR-GLOBWB (van Beek et al., 2011) runs at a relatively coarse spatial grid (i.e. 0.5° or about 50 km at the equator), which is well below the hyper resolution envisioned in the Grand Challenge (i.e. 100 m). The development of such a hyper resolution model requires utilizing recent computational advances and massive parallel computer systems. So far, the hydrological community has not yet made full use of such possibilities. The eWaterCycle is a close cooperation between hydrologists (Delft University of Technology and Utrecht University) and the Netherlands eScience Center (NLeSC) - that intends to supports and reinforce data-intensive research through creative and innovative use of information and communication technology (ICT). In this project, we modify and extend PCR-GLOBWB so that it runs at much higher resolution, on the order of 1 km or finer. This model refinement is a huge step forward as increasing resolution also requires adding an explicit spatial representation of local processes (groundwater flow, water diversions, glaciers, etc.) that greatly enhance the regional to local applicability of the model. In this project, we also aim to run the model operationally with a data assimilation scheme that incorporates satellite soil moisture observations and other relevant variables. The outcome of the eWaterCycle project will be relevant for addressing critical water cycle science questions and hydrological applications such as assessing water resources sustainability, flood and drought frequency under climate change. For this session, we intend to share and discuss some first results of this novel hydrological model.

Drost, N.; Sutanudjaja, E.; Hut, R.; Steele-Dunne, S. C.; de Jong, K.; Van Beek, L. P.; Karssenberg, D.; Bierkens, M. F.; Van De Giesen, N.

2013-12-01

342

Physically based distributed hydrological modelling of the Upper Jordan catchment and investigation of effective model equations  

NASA Astrophysics Data System (ADS)

Sufficient freshwater availability in the water scarce environment of the Upper Jordan Catchment (UJC) is a central prerequisite for peaceful agricultural and industrial development. Hydrological modelling is required to understand terrestrial water balance and to provide scientifically sound estimates on water availability. This article aims at two related objectives: First the water balance of the UJC, a hydrogeologically complex catchment located at the borders of Israel, Syria and the Lebanon, is investigated. It is for the first time that a physically based model is set up for this region that accounts both for the entire terrestrial water balance and in particular for the groundwater-surface water interaction. It is shown that the model is able to describe observed river discharges satisfactorily. Secondly, it is investigated if observed and simulated runoff components can be explained by simple lumped approaches based on 1) linear filter theory and 2) neural networks and what the number of degrees of freedom for the runoff components is. It is exemplary shown for the Ayun subcatchment of the UJC that the simulated river discharge, the direct runoff component and the interflow runoff component as modelled by the physically based distributed hydrological model WaSiM can be described by simple effective equations with only 3 to 5 degrees of freedom. Application of simple lumped approaches to observed river discharge values showed much weaker performance.

Kunstmann, H.; Heckl, A.; Rimmer, A.

2006-09-01

343

Integrating hydrologic and ecologic processes by coupling models in Sahelian context  

NASA Astrophysics Data System (ADS)

Vegetation cover change modifies the hydric transfers in an ecosystem. Change from natural cover to culture upsets not only the runoff rates, but also the depths of water root uptake. In semi-arid zone, these changes can be combined with fast and strong soil degradation. Simulation models at the scale of the small watershed are useful to understand the interactions between vegetation and hydrological processes. Coupling a 3D spatially explicit vegetation model and a fully distributed hydrological model, allows to evidence the impacts of vegetation change cover. The model of vegetation TREEGRASS (Simioni and al, 2000) previously developed to study the relations between grass and trees in wet savannah has been adapted to the Sahelian context for a watershed in Niger. The hydrological model r.water.fea (Vieux and Gaur, 1994), adapted to the Sahelian case is evenemential, soil water redistribution (evapotranspiration, deep drainage) between rain events is not implemented. The two models run at distinct time and spatial scales: r.water.fea calculates runoff at each node of the catchment during the rain event with a fine time-step; TREEGRASS runs daily for a season and a parcel of 1ha. These scale differences allow for non-incorporative coupling: TREEGRASS computes daily the primary production and the evapotranspiration in each class of vegetation representative of the basin. Just before the rain event, TREEGRASS gives the soil water content to r.water.fea, which computes storm runoff, and delivers to the vegetation model the soil water content at the end of the rain event. With the new soil water availability, TREEGRASS calculates biomass until the next rainfall event. Benefit of the coupling for the vegetation model comes from the account of the run-on process in addition to direct rainfall as water sources available for infiltration. For the hydrologic model, soil water content calculated by the vegetation model modulates runoff production. Seasonal effects of vegetation on infiltration characteristics will be introduced in the hydrological model.

Boulain, N.; Cappelaere, B.; Séguis, L.; Gignoux, J.

2003-04-01

344

Flood forecasting using a fully distributed model: application of the TOPKAPI model to the Upper Xixian Catchment Hydrology and Earth System Sciences, 9(4), 347364 (2005) EGU  

E-print Network

Xixian Catchment 347 Hydrology and Earth System Sciences, 9(4), 347364 (2005) © EGU Flood forecasting Liu1 , Mario L.V. Martina2 and Ezio Todini2 1 Bureau of Hydrology, Ministry of Water Resources, 2 Lane TOPKAPI is a physically-based, fully distributed hydrological model with a simple and parsimonious

Paris-Sud XI, Université de

345

Multi-Model Combination techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results  

SciTech Connect

This paper examines several multi-model combination techniques: the Simple Multi-model Average (SMA), the Multi-Model Super Ensemble (MMSE), Modified Multi-Model Super Ensemble (M3SE) and the Weighted Average Method (WAM). These model combination techniques were evaluated using the results from the Distributed Model Intercomparison Project (DMIP), an international project sponsored by the National Weather Service (NWS) Office of Hydrologic Development (OHD). All of the multi-model combination results were obtained using uncalibrated DMIP model outputs and were compared against the best uncalibrated as well as the best calibrated individual model results. The purpose of this study is to understand how different combination techniques affect the skill levels of the multi-model predictions. This study revealed that the multi-model predictions obtained from uncalibrated single model predictions are generally better than any single member model predictions, even the best calibrated single model predictions. Furthermore, more sophisticated multi-model combination techniques that incorporated bias correction steps work better than simple multi-model average predictions or multi-model predictions without bias correction.

Ajami, N K; Duan, Q; Gao, X; Sorooshian, S

2005-04-11

346

Hydrologic modelling for Lake Basaka: development and application of a conceptual water budget model.  

PubMed

Quantification of fluxes of water into and out of terminal lakes like Basaka has fundamental challenges. This is due to the fact that accurate measurement and quantification of most of the parameters of a lake's hydrologic cycle are difficult. Furthermore, quantitative understanding of the hydrologic systems and hence, the data-intensive modelling is difficult in developing countries like Ethiopia due to limitation of sufficient recorded data. Therefore, formulation of a conceptual water balance model is extremely important as it presents a convenient analytical tool with simplified assumptions to simulate the magnitude of unknown fluxes. In the current study, a conceptual lake water balance model was systematically formulated, solved, calibrated, and validated successfully. Then, the surface water and groundwater interaction was quantified, and a mathematical relationship developed. The overall agreement between the observed and simulated lake stage at monthly time step was confirmed based on the standard performance parameters (R(2), MAE, RMSE, E(f)). The result showed that hydrological water balance of the lake is dominated by the groundwater (GW) component. The net GW flux in recent period (post-2000s) accounts about 56% of the total water inflow. Hence, GW plays a leading role in the hydrodynamics and existence of Lake Basaka and is mostly responsible for the expansion of the lake. Thus, identification of the potential sources/causes for the GW flux plays a leading role in order to limit the further expansion of the lake. Measurement of GW movement and exchange in the area is a high priority for future research. PMID:24816590

Dinka, Megersa O; Loiskandl, Willibald; Ndambuki, Julius M

2014-09-01

347

Hydrologic modeling to predict performance of shallow land burial cover designs at the Los Alamos National Laboratory  

SciTech Connect

The water balance relationships of two shallow land burial (SLB) cover configurations were studied using a hydrologic model in a preliminary attempt to design waste disposal site covers for successful long-term closure at Los Alamos. Burial site performance requirements for site closure are first discussed, along with the role of hydrologic models in assessing the dynamics of the hydrology of the SLB cover. The calibration of a hydrologic model using field data from two SLB cover designs is then described, followed by an analysis of long-term climatic model input parameters across Los Alamos National Laboratory. These two calibrated models are then used to evaluate the influence of vegetation, precipitation, and runoff curve number on the design of SLB covers within Los Alamos county. Future directions of field research efforts and subsequent hydrologic modeling activities were recommended in terms of their usefulness for waste management decisions to be made at Los Alamos. 24 refs., 17 figs., 9 tabs.

Nyhan, J.W.

1989-03-01

348

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

349

On the dialog between experimentalist and modeler in catchment hydrology: Use of soft data for multicriteria model calibration  

Microsoft Academic Search

The dialog between experimentalist and modeler in catchment hydrology has been minimal to date. The experimentalist often has a highly detailed yet highly qualitative understanding of dominant runoff processes; thus there is often much more information content on the catchment than we use for calibration of a model. While modelers often appreciate the need for ``hard data'' for the model

Jan Seibert; Jeffrey J. McDonnell

2002-01-01

350

Influence of runoff parameterization on continental hydrology: Comparison between the Noah and the ISBA land surface models  

Microsoft Academic Search

A comprehensive set of hydrological parameterizations without any basin-scale calibration was recently introduced into the global ISBA land surface model in order to improve the simulation of the hydrological impacts of both seasonal climate anomalies and global warming. In this study, the same approach is introduced into the Noah land surface model, in order to improve the representation of surface

B. Decharme

2007-01-01

351

Assessing agriculture–water links at the basin scale: hydrologic and economic models of the São Francisco River Basin, Brazil  

Microsoft Academic Search

This article uses a basin-wide hydrologic model to assess the hydrologic and economic effects of expanding agriculture in the São Francisco River Basin, Brazil. It then uses a basin-wide economic model of agriculture to examine the effects of implementing water use regulations. Preliminary results suggest that substantially expanding agriculture would put pressure on some of the river's environmental flows. Agricultural

Marco Maneta; Marcelo Torres; Stephen A. Vosti; Wesley W. Wallender; Summer Allen; Luís H. Bassoi; Lisa Bennett; Richard Howitt; Lineu Rodrigues; Julie Young

2009-01-01

352

Assessing the Effect of Spatial Variability of Precipitation on Hydrologic Processes in Watersheds and Sensitivity Analyses of a Distributed Hydrologic Model  

NASA Astrophysics Data System (ADS)

: The effect of spatial variability of precipitation on hydrologic processes was studied using a physically-based spatially-distributed hydrologic model. The sensitivity of the hydrologic model to model parameters was investigated using fractional factorial design method. Point measurements of precipitation in the Monongahela river basin (13,187 km2 areal extent), a sub-basin in the Ohio river basin, were used to obtain the spatially distributed precipitation over the entire river basin using various interpolating techniques. One unique challenge in modeling the hydrologic regime of the Monongahela river basin is the complex spatial variability of the soil-terrain-hydrogeology system. In the Appalachian Plateau, at elevations above 400-500 m, the bedrock is highly dissected, and it consists of sandstone with almost flat-lying layers of shale, clay, siltstone, and dense limestone. The soil layers above the bedrock are very thin, and thus most of the rainfall runs off the slopes. The little amounts of water that infiltrate move vertically through fractures, and then move horizontally through sandstone or coal layers over large distances until they find another region of fractures, or an unconfined flow region such as colluvium and alluvium deposits. Accordingly, the base flow and interflow is very small during non-rainy periods in the warm season. At low elevations, productive unconsolidated alluvial aquifers ensure a significant and sustained baseflow and interflow contributions during summer months. The vegetation cover in the watershed area presents significant spatial variability. The land surface is dominantly covered by deciduous trees at high elevations and by short grass and crops at low elevations. Analysis of model results will focus on assessing the spatial and temporal non-linearity in the simulations of the hydrologic regime in the Monongahela river basin for two 5 months period in 1993 (a wet hydrologic year) and 1988 (a drought year) with respect to spatial variability of precipitation, surface-shallow groundwater interactions, and vegetation.

Yildiz, O.; Barros, A. P.

2001-05-01

353

Reconstitution of hepatitis B virus (HBV)-specific T cell responses with treatment of human immunodeficiency virus/HBV coinfection.  

PubMed

Liver-related mortality is an increasing problem in human immunodeficiency virus (HIV)/hepatitis B virus (HBV)-coinfected patients receiving highly active antiretroviral therapy (HAART). In HIV-negative patients, HBV chronicity is associated with a reduction in specific T cell responses that can be partially restored by treatment with lamivudine. We studied 5 HIV/HBV-coinfected patients treated with HAART, either with or without addition of a drug with specific anti-HBV activity. Our data show that reconstitution of some HBV-specific T cell responses can also occur in HIV-positive patients after a reduction in HBV load. This potential to recover T cell responses, which has been thought to be critical for HBV control, provides support for the addition of anti-HBV therapy in the treatment of HIV/HBV-coinfected patients. PMID:14673759

Lascar, R Monica; Gilson, Richard J; Lopes, A Ross; Bertoletti, Antonio; Maini, Mala K

2003-12-15

354

Land-use forecasting and hydrologic model integration for improved land-use decision support  

Microsoft Academic Search

This paper develops a methodology for integrating a land-use forecasting model with an event scale, rainfall-runoff model in support of improving land-use policy formulation at the watershed scale. The models selected for integration are loosely coupled, structured upon a common GIS platform that facilitates data exchange. The hydrologic model HEC-HMS is calibrated for a specific storm event that occurred within

Chris McColl; Graeme Aggett

2007-01-01

355

Intercomparison of mesoscale meteorological models for precipitation forecasting Hydrology and Earth System Sciences, 7(6), 799811 (2003) EGU  

E-print Network

Intercomparison of mesoscale meteorological models for precipitation forecasting 799 Hydrology and Earth System Sciences, 7(6), 799811 (2003) © EGU Intercomparison of mesoscale meteorological models, a series of past heavy precipitation events has been simulated with different meteorological models

Boyer, Edmond

356

Wavelet-based multiscale performance analysis: An approach to assess and improve hydrological models  

NASA Astrophysics Data System (ADS)

temporal dynamics of hydrological processes are spread across different time scales and, as such, the performance of hydrological models cannot be estimated reliably from global performance measures that assign a single number to the fit of a simulated time series to an observed reference series. Accordingly, it is important to analyze model performance at different time scales. Wavelets have been used extensively in the area of hydrological modeling for multiscale analysis, and have been shown to be very reliable and useful in understanding dynamics across time scales and as these evolve in time. In this paper, a wavelet-based multiscale performance measure for hydrological models is proposed and tested (i.e., Multiscale Nash-Sutcliffe Criteria and Multiscale Normalized Root Mean Square Error). The main advantage of this method is that it provides a quantitative measure of model performance across different time scales. In the proposed approach, model and observed time series are decomposed using the Discrete Wavelet Transform (known as the à trous wavelet transform), and performance measures of the model are obtained at each time scale. The applicability of the proposed method was explored using various case studies--both real as well as synthetic. The synthetic case studies included various kinds of errors (e.g., timing error, under and over prediction of high and low flows) in outputs from a hydrologic model. The real time case studies investigated in this study included simulation results of both the process-based Soil Water Assessment Tool (SWAT) model, as well as statistical models, namely the Coupled Wavelet-Volterra (WVC), Artificial Neural Network (ANN), and Auto Regressive Moving Average (ARMA) methods. For the SWAT model, data from Wainganga and Sind Basin (India) were used, while for the Wavelet Volterra, ANN and ARMA models, data from the Cauvery River Basin (India) and Fraser River (Canada) were used. The study also explored the effect of the choice of the wavelets in multiscale model evaluation. It was found that the proposed wavelet-based performance measures, namely the MNSC (Multiscale Nash-Sutcliffe Criteria) and MNRMSE (Multiscale Normalized Root Mean Square Error), are a more reliable measure than traditional performance measures such as the Nash-Sutcliffe Criteria (NSC), Root Mean Square Error (RMSE), and Normalized Root Mean Square Error (NRMSE). Further, the proposed methodology can be used to: i) compare different hydrological models (both physical and statistical models), and ii) help in model calibration.

Rathinasamy, Maheswaran; Khosa, Rakesh; Adamowski, Jan; ch, Sudheer; Partheepan, G.; Anand, Jatin; Narsimlu, Boini

2014-12-01

357

Review of Understanding of Earth's Hydrological Cycle: Observations, Theory and Modelling  

NASA Astrophysics Data System (ADS)

Water is our most precious and arguably most undervalued natural resource. It is essential for life on our planet, for food production and economic development. Moreover, water plays a fundamental role in shaping weather and climate. However, with the growing global population, the planet's water resources are constantly under threat from overuse and pollution. In addition, the effects of a changing climate are thought to be leading to an increased frequency of extreme weather causing floods, landslides and drought. The need to understand and monitor our environment and its resources, including advancing our knowledge of the hydrological cycle, has never been more important and apparent. The best approach to do so on a global scale is from space. This paper provides an overview of the major components of the hydrological cycle, the status of their observations from space and related data products and models for hydrological variable retrievals. It also lists the current and planned satellite missions contributing to advancing our understanding of the hydrological cycle on a global scale. Further details of the hydrological cycle are substantiated in several of the other papers in this Special Issue.

Rast, Michael; Johannessen, Johnny; Mauser, Wolfram

2014-05-01