Denatured ethanol release into gasoline residuals, Part 1: source behaviour.

PubMed

Freitas, Juliana G; Barker, James F

2013-05-01

With the increasing use of ethanol in fuels, it is important to evaluate its fate when released into the environment. While ethanol is less toxic than other organic compounds present in fuels, one of the concerns is the impact ethanol might have on the fate of gasoline hydrocarbons in groundwater. One possible concern is the spill of denatured ethanol (E95: ethanol containing 5% denaturants, usually hydrocarbons) in sites with pre-existing gasoline contamination. In that scenario, ethanol is expected to increase the mobility of the NAPL phase by acting as a cosolvent and decreasing interfacial tension. To evaluate the E95 behaviour and its impacts on pre-existing gasoline, a field test was performed at the CFB-Borden aquifer. Initially gasoline contamination was created releasing 200 L of E10 (gasoline with 10% ethanol) into the unsaturated zone. One year later, 184 L of E95 was released on top of the gasoline contamination. The site was monitored using soil cores, multilevel wells and one glass access tube. At the end of the test, the source zone was excavated and the compounds remaining were quantified. E95 ethanol accumulated and remained within the capillary fringe and unsaturated zone for more than 200 days, despite ~1m oscillations in the water table. The gasoline mobility increased and it was redistributed in the source zone. Gasoline NAPL saturations in the soil increased two fold in the source zone. However, water table oscillations caused a separation between the NAPL and ethanol: NAPL was smeared and remained in deeper positions while ethanol moved upwards following the water table rise. Similarly, the E95 denaturants that initially were within the ethanol-rich phase became separated from ethanol after the water table oscillation, remaining below the ethanol rich zone. The separation between ethanol and hydrocarbons in the source after water table oscillation indicates that ethanol's impact on hydrocarbon residuals is likely limited to early times. Copyright © 2013 Elsevier B.V. All rights reserved.

Response of anaerobic carbon cycling to water table manipulation in an Alaskan rich fen

USGS Publications Warehouse

Kane, E.S.; Chivers, M.R.; Turetsky, M.R.; Treat, C.C.; Petersen, D.G.; Waldrop, M.; Harden, J.W.; McGuire, A.D.

2013-01-01

To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 ± 0.9 μmol C g−1 d−1) was as high as aerobic CO2 production potential (10.6 ± 1.5 μmol C g−1 d−1), while CH4 production was low (mean of 7.8 ± 1.5 nmol C g−1 d−1). Denitrification enzyme activity indicated a very high denitrification potential (197 ± 23 μg N g−1 d−1), but net NO-3 reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances of denitrifier genes (nirK and nosZ) did not change across water table treatments. SO2-4 reduction also did not appear to be an important pathway for anaerobic CO2 production. The net accumulation of acetate and formate as decomposition end products in the raised water table treatment suggested that fermentation was a significant pathway for carbon mineralization, even in the presence of NO-3. Dissolved organic carbon (DOC) concentrations were the strongest predictors of potential anaerobic and aerobic CO2 production. Across all water table treatments, the CO2:CH4 ratio increased with initial DOC leachate concentrations. While the field water table treatment did not have a significant effect on mean CO2 or CH4 production potential, the CO2:CH4 ratio was highest in shallow peat incubations from the drained treatment. These data suggest that with continued drying or with a more variable water table, anaerobic CO2 production may be favored over CH4 production in this rich fen. Future research examining the potential for dissolved organic substances to facilitate anaerobic respiration, or alternative redox processes that limit the effectiveness of organic acids as substrates in anaerobic metabolism, would help explain additional uncertainty concerning carbon mineralization in this system.

Balancing practicality and hydrologic realism: a parsimonious approach for simulating rapid groundwater recharge via unsaturated-zone preferential flow

USGS Publications Warehouse

Mirus, Benjamin B.; Nimmo, J.R.

2013-01-01

The impact of preferential flow on recharge and contaminant transport poses a considerable challenge to water-resources management. Typical hydrologic models require extensive site characterization, but can underestimate fluxes when preferential flow is significant. A recently developed source-responsive model incorporates film-flow theory with conservation of mass to estimate unsaturated-zone preferential fluxes with readily available data. The term source-responsive describes the sensitivity of preferential flow in response to water availability at the source of input. We present the first rigorous tests of a parsimonious formulation for simulating water table fluctuations using two case studies, both in arid regions with thick unsaturated zones of fractured volcanic rock. Diffuse flow theory cannot adequately capture the observed water table responses at both sites; the source-responsive model is a viable alternative. We treat the active area fraction of preferential flow paths as a scaled function of water inputs at the land surface then calibrate the macropore density to fit observed water table rises. Unlike previous applications, we allow the characteristic film-flow velocity to vary, reflecting the lag time between source and deep water table responses. Analysis of model performance and parameter sensitivity for the two case studies underscores the importance of identifying thresholds for initiation of film flow in unsaturated rocks, and suggests that this parsimonious approach is potentially of great practical value.

Multiple-methods investigation of recharge at a humid-region fractured rock site, Pennsylvania, USA

USGS Publications Warehouse

Heppner, C.S.; Nimmo, J.R.; Folmar, G.J.; Gburek, W.J.; Risser, D.W.

2007-01-01

Lysimeter-percolate and well-hydrograph analyses were combined to evaluate recharge for the Masser Recharge Site (central Pennsylvania, USA). In humid regions, aquifer recharge through an unconfined low-porosity fractured-rock aquifer can cause large magnitude water-table fluctuations over short time scales. The unsaturated hydraulic characteristics of the subsurface porous media control the magnitude and timing of these fluctuations. Data from multiple sets of lysimeters at the site show a highly seasonal pattern of percolate and exhibit variability due to both installation factors and hydraulic property heterogeneity. Individual event analysis of well hydrograph data reveals the primary influences on water-table response, namely rainfall depth, rainfall intensity, and initial water-table depth. Spatial and seasonal variability in well response is also evident. A new approach for calculating recharge from continuous water-table elevation records using a master recession curve (MRC) is demonstrated. The recharge estimated by the MRC approach when assuming a constant specific yield is seasonal to a lesser degree than the recharge estimate resulting from the lysimeter analysis. Partial reconciliation of the two recharge estimates is achieved by considering a conceptual model of flow processes in the highly-heterogeneous underlying fractured porous medium. ?? Springer-Verlag 2007.

Groundwater flood of a river terrace in southwest Wisconsin, USA

NASA Astrophysics Data System (ADS)

Gotkowitz, Madeline B.; Attig, John W.; McDermott, Thomas

2014-09-01

Intense rainstorms in 2008 resulted in wide-spread flooding across the Midwestern United States. In Wisconsin, floodwater inundated a 17.7-km2 area on an outwash terrace, 7.5 m above the mapped floodplain of the Wisconsin River. Surface-water runoff initiated the flooding, but results of field investigation and modeling indicate that rapid water-table rise and groundwater inundation caused the long-lasting flood far from the riparian floodplain. Local geologic and geomorphic features of the landscape lead to spatial variability in runoff and recharge to the unconfined sand and gravel aquifer, and regional hydrogeologic conditions increased groundwater discharge from the deep bedrock aquifer to the river valley. Although reports of extreme cases of groundwater flooding are uncommon, this occurrence had significant economic and social costs. Local, state and federal officials required hydrologic analysis to support emergency management and long-term flood mitigation strategies. Rapid, sustained water-table rise and the resultant flooding of this high-permeability aquifer illustrate a significant aspect of groundwater system response to an extreme precipitation event. Comprehensive land-use planning should encompass the potential for water-table rise and groundwater flooding in a variety of hydrogeologic settings, as future changes in climate may impact recharge and the water-table elevation.

Effect of Drainage and Management Practices on Hydrology of Pine Plantation

Treesearch

R. Wayne Skaggs; Devendra M. Amatya; G. M. Chescheir; C. D. Blanton; J. W. Gilliam

2006-01-01

This paper reviews results of long-term studies, initiated in the late 1980s, to determine the hydrologic and water quality impacts of drainage and related water and forest management practices on a poorly drained site in Carteret County, North Carolina. Three watersheds, each approximately 25 ha, were instrumented to measure and record drainage rate, water table depth...

Status of Civil Judicial Consent Decrees Addressing Combined Sewer Systems (CSOs)

EPA Pesticide Factsheets

Tracking table of civil consent decrees for combined sewer systems (CSOs). This supports the National Enforcement Initiative (NEI) for Keeping Raw Sewage and Contaminated Stormwater Out of Our Nation's Waters.

Illinois drainage water management demonstration project

USGS Publications Warehouse

Pitts, D.J.; Cooke, R.; Terrio, P.J.; ,

2004-01-01

Due to naturally high water tables and flat topography, there are approximately 4 million ha (10 million ac) of farmland artificially drained with subsurface (tile) systems in Illinois. Subsurface drainage is practiced to insure trafficable field conditions for farm equipment and to reduce crop stress from excess water within the root zone. Although drainage is essential for economic crop production, there have been some significant environmental costs. Tile drainage systems tend to intercept nutrient (nitrate) rich soil-water and shunt it to surface water. Data from numerous monitoring studies have shown that a significant amount of the total nitrate load in Illinois is being delivered to surface water from tile drainage systems. In Illinois, these drainage systems are typically installed without control mechanisms and allow the soil to drain whenever the water table is above the elevation of the tile outlet. An assessment of water quality in the tile drained areas of Illinois showed that approximately 50 percent of the nitrate load was being delivered through the tile systems during the fallow period when there was no production need for drainage to occur. In 1998, a demonstration project to introduce drainage water management to producers in Illinois was initiated by NRCS4 An initial aspect of the project was to identify producers that were willing to manage their drainage system to create a raised water table during the fallow (November-March) period. Financial assistance from two federal programs was used to assist producers in retrofitting the existing drainage systems with control structures. Growers were also provided guidance on the management of the structures for both water quality and production benefits. Some of the retrofitted systems were monitored to determine the effect of the practice on water quality. This paper provides background on the water quality impacts of tile drainage in Illinois, the status of the demonstration project, preliminary monitoring results, and other observations.

Water Table Depth and Growth of Young Cottonwood

Treesearch

W. M. Broadfoot

1973-01-01

Planted cottonwood grew best when the water table was about 2 feet deep, whether the tree was planted on soil with a high water table or the water table was raised 1 year after planting. Growth over a 1- foot-deep water table was about the same as over no water table, but a surface water table restricted growth of cuttings planted in the water, and killed trees planted...

Depth dependent microbial carbon use efficiency in the capillary fringe as affected by water table fluctuations in a column incubation experiment

NASA Astrophysics Data System (ADS)

Pronk, G. J.; Mellage, A.; Milojevic, T.; Smeaton, C. M.; Rezanezhad, F.; Van Cappellen, P.

2017-12-01

Microbial growth and turnover of soil organic carbon (SOC) depend on the availability of electron donors and acceptors. The steep geochemical gradients in the capillary fringe between the saturated and unsaturated zones provide hotspots of soil microbial activity. Water table fluctuations and the associated drying and wetting cycles within these zones have been observed to lead to enhanced turnover of SOC and adaptation of the local microbial communities. To improve our understanding of SOC degradation under changing moisture conditions, we carried out an automated soil column experiment with integrated of hydro-bio-geophysical monitoring under both constant and oscillating water table conditions. An artificial soil mixture composed of quartz sand, montmorillonite, goethite and humus was used to provide a well-defined system. This material was inoculated with a microbial community extracted from a forested riparian zone. The soils were packed into 6 columns (60 cm length and 7.5 cm inner diameter) to a height of 45 cm; and three replicate columns were incubated under constant water table while another three were saturated and drained monthly. The initial soil development, carbon cycling and microbial community development were then characterized during 10 months of incubation. This system provides an ideal artificial gradient from the saturated to the unsaturated zone to study soil development from initially homogeneous materials and the same microbial community composition under controlled conditions. Depth profiles of SOC and microbial biomass after 329 days of incubation showed a depletion of carbon in the transition drying and wetting zone that was not associated with higher accumulation of microbial biomass, indicating a lower carbon use efficiency of the microbial community established within the water table fluctuation zone. This was supported by a higher ATP to microbial biomass carbon ratio within the same zone. The findings from this study highlight the importance of considering the effects of transient soil moisture and oxygen availability on microbial mediated SOC transformations. The effects of these changes in carbon use efficiency need to be included in soil models in order to accurately predict SOC turnover.

Stemflow-induced processes of soil water storage

NASA Astrophysics Data System (ADS)

Germer, Sonja

2013-04-01

Compared to stemflow production studies only few studies deal with the fate of stemflow at the near-stem soil. To investigate stemflow contribution to the root zone soil moisture by young and adult babassu palms (Attalea speciosa Mart.), I studied stemflow generation, subsequent soil water percolation and root distributions. Rainfall, stemflow and perched water tables were monitored on an event basis. Perched water tables were monitored next to adult palms at two depths and three stem distances. Dye tracer experiments monitored stemflow-induced preferential flow paths. Root distributions of fine and coarse roots were related to soil water redistribution. Average rainfall-collecting area per adult palm was 6.4 m², but variability between them was high. Funneling ratios ranged between 16-71 and 4-55 for adult and young palms, respectively. Nonetheless, even very small rainfall events of 1 mm can generate stemflow. On average, 9 liters of adult palm stemflow were intercepted and stemflow tended to decrease for-high intensity rainfall events. Young babassu palms funneled rainfall via their fronds, directly to their subterranean stems. The funneling of rainfall towards adult palm stems, in contrast, led to great stemflow fluxes down to the soil and induced initial horizontal water flows through the soil, leading to perched water tables next to palms, even after small rainfall events. The perched water tables extended, however, only a few decimeters from palm stems. After perched water tables became established, vertical percolation through the soil dominated. To my knowledge, this process has not been described before, and it can be seen as an addition to the two previously described stemflow-induced processes of Horton overland flow and fast, deep percolation along roots. This study has demonstrated that Babassu palms funnel water to their stems and subsequently store it in the soil next to their stems in areas where coarse root length density is very high. This might partly explain the competitive position of babassu palms on pastures or secondary forests.

Estimating the timing and location of shallow rainfall-induced landslides using a model for transient, unsaturated infiltration

USGS Publications Warehouse

Baum, Rex L.; Godt, Jonathan W.; Savage, William Z.

2010-01-01

Shallow rainfall-induced landslides commonly occur under conditions of transient infiltration into initially unsaturated soils. In an effort to predict the timing and location of such landslides, we developed a model of the infiltration process using a two-layer system that consists of an unsaturated zone above a saturated zone and implemented this model in a geographic information system (GIS) framework. The model links analytical solutions for transient, unsaturated, vertical infiltration above the water table to pressure-diffusion solutions for pressure changes below the water table. The solutions are coupled through a transient water table that rises as water accumulates at the base of the unsaturated zone. This scheme, though limited to simplified soil-water characteristics and moist initial conditions, greatly improves computational efficiency over numerical models in spatially distributed modeling applications. Pore pressures computed by these coupled models are subsequently used in one-dimensional slope-stability computations to estimate the timing and locations of slope failures. Applied over a digital landscape near Seattle, Washington, for an hourly rainfall history known to trigger shallow landslides, the model computes a factor of safety for each grid cell at any time during a rainstorm. The unsaturated layer attenuates and delays the rainfall-induced pore-pressure response of the model at depth, consistent with observations at an instrumented hillside near Edmonds, Washington. This attenuation results in realistic estimates of timing for the onset of slope instability (7 h earlier than observed landslides, on average). By considering the spatial distribution of physical properties, the model predicts the primary source areas of landslides.

How well do testate amoebae transfer functions relate to high-resolution water-table records?

NASA Astrophysics Data System (ADS)

Holden, Joseph; Swindles, Graeme; Raby, Cassandra; Blundell, Antony

2014-05-01

Testate amoebae (TA) community composition records from peat cores are often used to infer past water-table conditions on peatland sites. However, one of the problems is that validation of water-table depths used in such work typically comes from a one-off water-table measurement or a few measurements of water-table depth from the testate amoebae sample extraction point. Furthermore, one value of water-table depth is produced by the transfer function reconstruction, with sample-specific errors generated through a statistical resampling approach. However, we know that water tables fluctuate in peatlands and are dynamic. Traditional TA water-table data may not adequately capture a mean value from a site, and may not account for water-table dynamics (e.g. seasonal or annual variability) that could influence the TA community composition. We analysed automatically logged (at least hourly, mainly 15-min) peatland water-table data from 72 different dipwells located across northern Sweden, Wales and the Pennine region of England. Each location had not been subject to recent management intervention. A suite of characteristics of water-table dynamics for each point were determined. At each point surface samples were extracted and the TA community composition was determined. Our results show that estimated water-table depth based on the TA community transfer functions poorly represents the real mean or median water tables for the study sites. The TA approach does, however, generally identify sites that have water tables that are closer to the surface for a greater proportion of the year compared to sites with deeper water tables for large proportions of the year. However, the traditional TA approach does not differentiate between sites with similar mean (or median) water-table depths yet which have quite different water table variability (e.g. interquartile range). We suggest some ways of improving water-table metrics for use in Holocene peatland hydrology reconstructions.

Linking soil moisture balance and source-responsive models to estimate diffuse and preferential components of groundwater recharge

USGS Publications Warehouse

Cuthbert, M.O.; Mackay, R.; Nimmo, J.R.

2012-01-01

Results are presented of a detailed study into the vadose zone and shallow water table hydrodynamics of a field site in Shropshire, UK. A conceptual model is developed and tested using a range of numerical models, including a modified soil moisture balance model (SMBM) for estimating groundwater recharge in the presence of both diffuse and preferential flow components. Tensiometry reveals that the loamy sand topsoil wets up via macropore flow and subsequent redistribution of moisture into the soil matrix. Recharge does not occur until near-positive pressures are achieved at the top of the sandy glaciofluvial outwash material that underlies the topsoil, about 1 m above the water table. Once this occurs, very rapid water table rises follow. This threshold behaviour is attributed to the vertical discontinuity in the macropore system due to seasonal ploughing of the topsoil, and a lower permeability plough/iron pan restricting matrix flow between the topsoil and the lower outwash deposits. Although the wetting process in the topsoil is complex, a SMBM is shown to be effective in predicting the initiation of preferential flow from the base of the topsoil into the lower outwash horizon. The rapidity of the response at the water table and a water table rise during the summer period while flow gradients in the unsaturated profile were upward suggest that preferential flow is also occurring within the outwash deposits below the topsoil. A variation of the source-responsive model proposed by Nimmo (2010) is shown to reproduce the observed water table dynamics well in the lower outwash horizon when linked to a SMBM that quantifies the potential recharge from the topsoil. The results reveal new insights into preferential flow processes in cultivated soils and provide a useful and practical approach to accounting for preferential flow in studies of groundwater recharge estimation.

Fluvial valleys in the heavily cratered terrains of Mars: Evidence for paleoclimatic change?

NASA Technical Reports Server (NTRS)

Gulick, V. C.; Baker, V. R.

1993-01-01

Whether the formation of the Martian valley networks provides unequivocal evidence for drastically different climatic conditions remains debatable. Recent theoretical climate modeling precludes the existence of a temperate climate early in Mars' geological history. An alternative hypothesis suggests that Mars had a globally higher heat flow early in its geological history, bringing water tables to within 350 m of the surface. While a globally higher heat flow would initiate ground water circulation at depth, the valley networks probably required water tables to be even closer to the surface. Additionally, it was previously reported that the clustered distribution of the valley networks within terrain types, particularly in the heavily cratered highlands, suggests regional hydrological processes were important. The case for localized hydrothermal systems is summarized and estimates of both erosion volumes and of the implied water volumes for several Martian valley systems are presented.

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

Friedrichs, D.R.; Cole, C.R.; Arnett, R.C.

The Hanford Pathline Calculational Program (HPCP) is a numerical model developed to predict the movement of fluid particles from one location to another within the Hanford or similar groundwater systems. As such it can be considered a simple transport model wherein only advective changes are considered. Application of the numerical HPCP to test cases for which semianalytical results are obtainable showed that with reasonable time steps and the grid spacing requirements HPCP give good agreement with the semianalytical solution. The accuracy of the HPCP results is most sensitive in areas near steep or rapidly changing potential gradients and may requiremore » finer grid spacing in those areas than for the groundwater system as a whole. Initial applications of HPCP to the Hanford groundwater flow regime show that significant differences (improvements) in the predictions of fluid particle movement are obtainable with the pathline approach (changing groundwater potential or water table surface) as opposed to the streamline approach (unchanging potential or water table surface) used in past Hanford groundwater analyses. This report documents capability developed for estimating groundwater travel times from the Hanford high-level waste areas to the Columbia River at different water table levels.« less

Soil Water and Shallow Groundwater Relations in an Agricultural Hillslope

NASA Astrophysics Data System (ADS)

Logsdon, S. D.; Schilling, K. E.

2007-12-01

Shallow water tables contribute to soil water variations under rolling topography, and soil properties contribute to shallow water table fluctutations. Preferential flow through large soil pores can cause a rise in the water table with little increase in soil water except near the soil surface. Lateral groundwater flow can cause a large rise in water table at toeslope and depressional landscape positions. As plants transpire, water can move up into the root zone from the water table and wet soil below the root zone. Roots can utilize water in the capillary fringe. The purpose of this study was to interface automated measurements of soil water content and water table depth for determining the importance of drainage and upward movement. In 2006 soil water and water table depth were monitored at three positions: shoulder, backslope, and toeslope. Neutron access tubes were manually monitored to 2.3 m depth, and automated soil moisture was measured using CS616 probes installed at 0.3, 0.5, 0.7, and 0.9 m depth. Water table depths were monitored manually and automated, but the automated measurements failed during the season at two sites. In 2007, similar measurements were made at one toeslope position, but the CS616 probes were installed at nine depths and better quality automated well depth equipment was used. The 2006 data revealed little landscape position effect on daytime soil water loss on a wetter date; however, on a dry day just before a rain, daytime water loss was greatest for the toeslope positon and least for the shoulder position. After a period of intense rain, a rapid and significant water table rise occurred at the toeslope position but little water table rise occurred at the other landscape positions. The rapid toeslope water table rise was likely caused by lateral groundwater flow whereas minor water table rise at the other positions was likely due to preferential flow since the soil had not wet up below 0.6 m. Use of automated equipment has improved our understanding of the relations of soil water to water table fluctuations in an agricultural field.

High-Resolution Assimilation of GRACE Terrestrial Water Storage Observations to Represent Local-Scale Water Table Depths

NASA Astrophysics Data System (ADS)

Stampoulis, D.; Reager, J. T., II; David, C. H.; Famiglietti, J. S.; Andreadis, K.

2017-12-01

Despite the numerous advances in hydrologic modeling and improvements in Land Surface Models, an accurate representation of the water table depth (WTD) still does not exist. Data assimilation of observations of the joint NASA and DLR mission, Gravity Recovery and Climate Experiment (GRACE) leads to statistically significant improvements in the accuracy of hydrologic models, ultimately resulting in more reliable estimates of water storage. However, the usually shallow groundwater compartment of the models presents a problem with GRACE assimilation techniques, as these satellite observations account for much deeper aquifers. To improve the accuracy of groundwater estimates and allow the representation of the WTD at fine spatial scales we implemented a novel approach that enables a large-scale data integration system to assimilate GRACE data. This was achieved by augmenting the Variable Infiltration Capacity (VIC) hydrologic model, which is the core component of the Regional Hydrologic Extremes Assessment System (RHEAS), a high-resolution modeling framework developed at the Jet Propulsion Laboratory (JPL) for hydrologic modeling and data assimilation. The model has insufficient subsurface characterization and therefore, to reproduce groundwater variability not only in shallow depths but also in deep aquifers, as well as to allow GRACE assimilation, a fourth soil layer of varying depth ( 1000 meters) was added in VIC as the bottom layer. To initialize a water table in the model we used gridded global WTD data at 1 km resolution which were spatially aggregated to match the model's resolution. Simulations were then performed to test the augmented model's ability to capture seasonal and inter-annual trends of groundwater. The 4-layer version of VIC was run with and without assimilating GRACE Total Water Storage anomalies (TWSA) over the Central Valley in California. This is the first-ever assimilation of GRACE TWSA for the determination of realistic water table depths, at fine scales that are required for local water management. In addition, Open Loop and GRACE-assimilation simulations of water table depth were compared to in-situ data over the state of California, derived from observation wells operated/maintained by the U.S. Geological Service.

Incorporating water table dynamics in climate modeling: 1. Water table observations and equilibrium water table simulations

NASA Astrophysics Data System (ADS)

Fan, Ying; Miguez-Macho, Gonzalo; Weaver, Christopher P.; Walko, Robert; Robock, Alan

2007-05-01

Soil moisture is a key participant in land-atmosphere interactions and an important determinant of terrestrial climate. In regions where the water table is shallow, soil moisture is coupled to the water table. This paper is the first of a two-part study to quantify this coupling and explore its implications in the context of climate modeling. We examine the observed water table depth in the lower 48 states of the United States in search of salient spatial and temporal features that are relevant to climate dynamics. As a means to interpolate and synthesize the scattered observations, we use a simple two-dimensional groundwater flow model to construct an equilibrium water table as a result of long-term climatic and geologic forcing. Model simulations suggest that the water table depth exhibits spatial organization at watershed, regional, and continental scales, which may have implications for the spatial organization of soil moisture at similar scales. The observations suggest that water table depth varies at diurnal, event, seasonal, and interannual scales, which may have implications for soil moisture memory at these scales.

Comment on “Reconciliation of the Devils Hole climate record with orbital forcing”

USGS Publications Warehouse

Winograd, Isaac J.

2016-01-01

Moseley et al. (Reports, 8 January 2016, p. 165) postulate an increase in dissolved thorium isotope 230Th with depth below the water table as the explanation for the differing ages of Termination II. Flow of geothermal water through the Devils Hole caverns precludes this explanation. Deposition of younger secondary calcite into the initial porosity of the calcite comprising their cores is a plausible alternate explanation.

Comment on “Reconciliation of the Devils Hole climate record with orbital forcing”

NASA Astrophysics Data System (ADS)

Winograd, Isaac J.

2016-10-01

Moseley et al. (Reports, 8 January 2016, p. 165) postulate an increase in dissolved thorium isotope 230Th with depth below the water table as the explanation for the differing ages of Termination II. Flow of geothermal water through the Devils Hole caverns precludes this explanation. Deposition of younger secondary calcite into the initial porosity of the calcite comprising their cores is a plausible alternate explanation.

Transport of volatile organic compounds across the capillary fringe

USGS Publications Warehouse

McCarthy, Kathleen A.; Johnson, Richard L.

1993-01-01

Physical experiments were conducted to investigate the transport of a dissolved volatile organic compound (trichloroethylene, TCE) from shallow groundwater to the unsaturated zone under a variety of conditions including changes in the soil moisture profile and water table position. Experimental data indicated that at moderate groundwater velocities (0.1 m/d), vertical mechanical dispersion was negligible and molecular diffusion was the dominant vertical transport mechanism. Under these conditions, TCE concentrations decreased nearly 3 orders of magnitude across the capillary fringe and soil gas concentrations remained low relative to those of underlying groundwater. Data collected during a water table drop showed a short-term increase in concentrations throughout most of the unsaturated zone, but these concentrations quickly declined and approached initial values after the water table was returned to its original level. In the deep part of the unsaturated zone, the water table drop resulted in a long-term decrease in concentrations, illustrating the effects of hysteresis in the soil moisture profile. A two-dimensional random walk advection-diffusion model was developed to simulate the experimental conditions, and numerical simulations agreed well with experimental data. A simpler, one-dimensional finite-difference diffusion-dispersion model was also developed. One-dimensional simulations based on molecular diffusion also agreed well with experimental data. Simulations which incorporated mechanical dispersion tended to overestimate flux across the capillary fringe. Good agreement between the one- and two-dimensional models suggested that a simple, one-dimensional approximation of vertical transport across the capillary fringe can be useful when conditions are appropriate.

40 CFR Appendix - Tables to Part 132

Code of Federal Regulations, 2010 CFR

2010-07-01

... Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY GUIDANCE FOR THE GREAT... Tables to Part 132 Table 1—Acute Water Quality Criteria for Protection of Aquatic Life in Ambient Water... FR 35286, June 2, 2000] Table 2—Chronic Water Quality Criteria for Protection of Aquatic Life in...

Enceladus: Starting Hydrothermal Activity

NASA Technical Reports Server (NTRS)

Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

2011-01-01

We describe a process for starting the hydrothermal activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.

Ground-water data: Beaver, Escalante, Cedar City, and Parowan Valleys; parts of Washington, Iron, Beaver, and Millard Counties, Utah

USGS Publications Warehouse

Sandberg, George W.

1963-01-01

This report is intended to serve two purposes: (1) to make available to the public basic ground-water data useful in planning and studying development of water resources, and (2) to supplement an interpretive report that will be published later.Records were collected during the period 1935-62 by the U.S. Geological Survey in cooperation with the Utah State Engineer as part of the investigation of ground-water conditions in the Beaver, Escalante, Cedar City, and Parowan Walleys. This report will include records collected subsequent to data published in earlier reports listed in the bibliography. The interpretive material will be published in a companion report by George W. Sandberg.This report is most useful in predicting conditions likely to be found in areas that are being considered as well sites. The person considering the new well can spot the proposed site on plate 1 and examine the records of nearby wells as shown in the tables and figure 2. From table 1 he can note such things as diameter, depth, water level, yield, use of water, and depth to aquifers in wells in the vicinity, and from the well logs in table 3 he can note the type of material that yields water to the wells. Table 2 gives several years record of yields and pumping levels of irrigation wells, and in table 4 are the chemical analyses of water from wells and springs. Figure 2 shows the historic fluctuations and trends of water levels in the four valleys. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the State Engineer. During the past several years, however, the State Engineer has rejected new applications to appropriate water in major portions of Beaver Valley, Milford and Beryl-Enterprise districts in Escalante Valley, and Cedar City Valley. Anyone seeking to initiate a new ground-water right in any of these areas should obtain information from the State Engineer's Office in either Salt Lake City or Cedar City to determine the likelihood of approval of the required application.The report is also useful when planning large-scale developments of water supply. This and other uses of the report will be helped by use of the interpretive report upon its release.

Estimated Depth to Ground Water and Configuration of the Water Table in the Portland, Oregon Area

USGS Publications Warehouse

Snyder, Daniel T.

2008-01-01

Reliable information on the configuration of the water table in the Portland metropolitan area is needed to address concerns about various water-resource issues, especially with regard to potential effects from stormwater injection systems such as UIC (underground injection control) systems that are either existing or planned. To help address these concerns, this report presents the estimated depth-to-water and water-table elevation maps for the Portland area, along with estimates of the relative uncertainty of the maps and seasonal water-table fluctuations. The method of analysis used to determine the water-table configuration in the Portland area relied on water-level data from shallow wells and surface-water features that are representative of the water table. However, the largest source of available well data is water-level measurements in reports filed by well constructors at the time of new well installation, but these data frequently were not representative of static water-level conditions. Depth-to-water measurements reported in well-construction records generally were shallower than measurements by the U.S. Geological Survey (USGS) in the same or nearby wells, although many depth-to-water measurements were substantially deeper than USGS measurements. Magnitudes of differences in depth-to-water measurements reported in well records and those measured by the USGS in the same or nearby wells ranged from -119 to 156 feet with a mean of the absolute value of the differences of 36 feet. One possible cause for the differences is that water levels in many wells reported in well records were not at equilibrium at the time of measurement. As a result, the analysis of the water-table configuration relied on water levels measured during the current study or used in previous USGS investigations in the Portland area. Because of the scarcity of well data in some areas, the locations of select surface-water features including major rivers, streams, lakes, wetlands, and springs representative of where the water table is at land surface were used to augment the analysis. Ground-water and surface-water data were combined for use in interpolation of the water-table configuration. Interpolation of the two representations typically used to define water-table position - depth to the water table below land surface and elevation of the water table above a datum - can produce substantially different results and may represent the end members of a spectrum of possible interpolations largely determined by the quantity of recharge and the hydraulic properties of the aquifer. Datasets of depth-to-water and water-table elevation for the current study were interpolated independently based on kriging as the method of interpolation with parameters determined through the use of semivariograms developed individually for each dataset. Resulting interpolations were then combined to create a single, averaged representation of the water-table configuration. Kriging analysis also was used to develop a map of relative uncertainty associated with the values of the water-table position. Accuracy of the depth-to-water and water-table elevation maps is dependent on various factors and assumptions pertaining to the data, the method of interpolation, and the hydrogeologic conditions of the surficial aquifers in the study area. Although the water-table configuration maps generally are representative of the conditions in the study area, the actual position of the water-table may differ from the estimated position at site-specific locations, and short-term, seasonal, and long-term variations in the differences also can be expected. The relative uncertainty map addresses some but not all possible errors associated with the analysis of the water-table configuration and does not depict all sources of uncertainty. Depth to water greater than 300 feet in the Portland area is limited to parts of the Tualatin Mountains, the foothills of the Cascade Range, and muc

Linking Water Table Dynamics to Carbon Cycling in Artificial Soil Column Incubations

NASA Astrophysics Data System (ADS)

Geertje, Pronk; Adrian, Mellage; Tatjana, Milojevic; Fereidoun, Rezanezhad; Cappellen Philippe, Van

2016-04-01

The biogeochemistry of wetlands soils is closely tied to their hydrology. Water table fluctuations that cause flooding and drying of these systems may lead to enhanced degradation of organic matter and release of greenhouse gasses (e.g. CO2, CH4) to the atmosphere. However, predicting the influence of water table fluctuations on the biogeochemical functioning of soils requires an understanding of the interactions of soil hydrology with biogeochemical and microbial processes. To determine the effects of water table dynamics on carbon cycling, we are carrying out state-of-the-art automated soil column experiments with fully integrated monitoring of hydro-bio-geophysical process variables under both constant and oscillating water table conditions. An artificial, homogeneous mixture consisting of minerals and organic matter is used to provide a well-defined starting material. The artificial soils are composed of quartz sand, montmorillonite, goethite and humus from a forested riparian zone, from which we also extracted the microbial inoculum added to the soil mixture. The artificial soils are packed into 60 cm high, 7.5 cm wide columns. In the currently ongoing experiment, three replicate columns are incubated while keeping the water table constant water at mid-depth, while another three columns alternate between drained and saturated conditions. Micro-sensors installed at different depths below the soil surface record time-series redox potentials (Eh) varying between oxidizing (~+700 mV) and reducing (~-200 mV) conditions. Continuous O2 levels throughout the soil columns are monitored using high-resolution, luminescence-based, Multi Fiber Optode (MuFO) microsensors. Pore waters are collected periodically with MicroRhizon samplers from different depths, and analyzed for pH, EC, dissolved inorganic and organic carbon and ion/cation compositions. These measurements allow us to track the changes in pore water geochemistry and relate them to differences in carbon cycling between the contrasting water table regimes. Particular attention is given to the mobilization and redistribution of iron from the initially homogeneously distributed goethite. In addition, small solid-phase samples are collected monthly from the saturated and unsaturated zones of the soil columns to characterize the microbial communities and changes in soil microstructure and organo-mineral associations. Headspace gas measurements are used to derive the effluxes of CO2 and CH4 during the experiment. Together, the experimental data will provide a comprehensive picture of the early development of the soil and the accompanying establishment of biogeochemical gradients under dynamic hydrological conditions. They will allow us to relate the degradation of soil organic matter and greenhouse gas emissions to the saturation conditions and redox chemistry under controlled conditions. The experiment is in progress with an expected total duration of 6 months.

Application of GPS and Near-Surface Geophysical Methods to Evaluate Agricultural Test Plot Differences

USDA-ARS?s Scientific Manuscript database

A field research facility with two pairs of replicated agricultural test plots (four total) was established at a location in northwest Ohio during 2005 for the purpose of studying water table management strategies. Initial efforts at this field research facility were devoted to evaluating difference...

[Effects of water table manipulation on leaf photosynthesis, morphology and growth of Phragmites australis and Imperata cylindrica in the reclaimed tidal wetland at Dongtan of Chongming Island, China].

PubMed

Zhong, Qi-Cheng; Wang, Jiang-Tao; Zhou, Jian-Hong; Ou, Qiang; Wang, Kai-Yun

2014-02-01

During the growing season of 2011, the leaf photosynthesis, morphological and growth traits of Phragmites australis and Imperata cylindrica were investigated along a gradient of water table (low, medium and high) in the reclaimed tidal wetland at the Dongtan of Chongming Island in the Yangtze Estuary of China. A series of soil factors, i. e., soil temperature, moisture, salinity and inorganic nitrogen content, were also measured. During the peak growing season, leaf photosynthetic capacity of P. australis in the wetland with high water table was significantly lower than those in the wetland with low and medium water tables, and no difference was observed in leaf photosynthetic capacity of I. cylindrica at the three water tables. During the entire growing season, at the shoot level, the morphological and growth traits of P. australis got the optimum in the wetland with medium water table, but most of the morphological and growth traits of I. cylindrica had no significant differences at the three water tables. At the population level, the shoot density, leaf area index and aboveground biomass per unit area were the highest in the wetland with high water table for P. australis, but all of the three traits were the highest in the wetland with low water table for I. cylindrica. At the early growing season, the rhizome biomass of P. australis in the 0-20 cm soil layer had no difference at the three water tables, and the rhizome biomass of I. cylindrica in the 0-20 cm soil layer in the wetland with high water table was significantly lower than those in the wetland with low and medium water table. As a native hygrophyte before the reclamation, the variations of performances of P. australis at the three water tables were probably attributed to the differences in the soil factors as well as the intensity of competition from I. cylindrica. To appropriately manipulate water table in the reclaimed tidal wetland may restrict the growth and propagation of the mesophyte I. cylindrica, and facilitate the restoration of P. australis-dominated marsh plant community.

A computer program for predicting recharge with a master recession curve

USGS Publications Warehouse

Heppner, Christopher S.; Nimmo, John R.

2005-01-01

Water-table fluctuations occur in unconfined aquifers owing to ground-water recharge following precipitation and infiltration, and ground-water discharge to streams between storm events. Ground-water recharge can be estimated from well hydrograph data using the water-table fluctuation (WTF) principle, which states that recharge is equal to the product of the water-table rise and the specific yield of the subsurface porous medium. The water-table rise, however, must be expressed relative to the water level that would have occurred in the absence of recharge. This requires a means for estimating the recession pattern of the water-table at the site. For a given site there is often a characteristic relation between the water-table elevation and the water-table decline rate following a recharge event. A computer program was written which extracts the relation between decline rate and water-table elevation from well hydrograph data and uses it to construct a master recession curve (MRC). The MRC is a characteristic water-table recession hydrograph, representing the average behavior for a declining water-table at that site. The program then calculates recharge using the WTF method by comparing the measured well hydrograph with the hydrograph predicted by the MRC and multiplying the difference at each time step by the specific yield. This approach can be used to estimate recharge in a continuous fashion from long-term well records. Presented here is a description of the code including the WTF theory and instructions for running it to estimate recharge with continuous well hydrograph data.

Effect of Water-Table Fluctuations on Source Depletion and Dissolved-Plume Behavior of a Multi-Component Light Nonaqueous-Phase Liquid

NASA Astrophysics Data System (ADS)

Dobson, R.; Schroth, M. H.; Zeyer, J.

2006-12-01

Light nonaqueous-phase liquids (LNAPLs) such as gasoline and diesel are among the most common soil and groundwater contaminants. Dissolution and subsequent advective transport of LNAPL components can negatively impact downgradient water supplies, while biodegradation is commonly thought to be an important sink for this class of contaminants. Water-table fluctuations, either naturally occurring or intentionally induced, may affect LNAPL component transport and biodegradation in aquifers. We present a laboratory investigation of the effect of water-table fluctuations on the dissolution and biodegradation of a multi-component LNAPL in a pair of similar model aquifers, one of which was subjected to a water-table fluctuation. Water-table fluctuation resulted in LNAPL and air entrapment below the water table, an increase in the vertical extent of LNAPL contamination and an increase in the volume of water passing through the contaminated zone. Effluent concentrations of dissolved LNAPL components were higher and those of dissolved nitrate were lower in the aquifer model where a fluctuation had been induced. Thus, water table fluctuation led to enhanced LNAPL dissolution as well as enhanced biodegradation activity. The increase in biodegradation observed after fluctuation was of lesser magnitude than the increase in LNAPL dissolution, such that water-table fluctuations might be expected to result in increased exposure of downgradient receptors to dissolved LNAPL components. Conversely, the potential for free-phase LNAPL migration was reduced following a water-table fluctuation, as LNAPL entrapment by the rising water table reduced the amount of free phase LNAPL. Lateral migration of LNAPL following emplacement was observed in the model aquifer where no fluctuation occurred, but not in the model aquifer where a water-table fluctuation was induced.

Water table dynamics in undisturbed, drained and restored blanket peat

NASA Astrophysics Data System (ADS)

Holden, J.; Wallage, Z. E.; Lane, S. N.; McDonald, A. T.

2011-05-01

SummaryPeatland water table depth is an important control on runoff production, plant growth and carbon cycling. Many peatlands have been drained but are now subject to activities that might lead to their restoration including the damming of artificial drains. This paper investigates water table dynamics on intact, drained and restored peatland slopes in a blanket peat in northern England using transects of automated water table recorders. Long-term (18 month), seasonal and short-term (storm event) records are explored. The restored site had drains blocked 6 years prior to monitoring commencing. The spatially-weighted mean water table depths over an 18 month period were -5.8 cm, -8.9 cm and -11.5 cm at the intact, restored and drained sites respectively. Most components of water table behaviour at the restored site, including depth exceedance probability curves, seasonality of water table variability, and water table responses to individual rainfall events were intermediate between that of the drained and intact sites. Responses also depended on location with respect to the drains. The results show that restoration of drained blanket peat is difficult and the water table dynamics may not function in the same way as those in undisturbed blanket peat even many years after management intervention. Further measurement of hydrological processes and water table responses to peatland restoration are required to inform land managers of the hydrological success of those projects.

Water-Table Levels and Gradients, Nevada, 1947-2004

USGS Publications Warehouse

Lopes, Thomas J.; Buto, Susan G.; Smith, J. LaRue; Welborn, Toby L.

2006-01-01

In 1999, the U.S. Environmental Protection Agency began a program to protect the quality of ground water in areas other than ground-water protection areas. These other sensitive ground water areas (OSGWA) are areas that are not currently, but could eventually be, used as a source of drinking water. The OSGWA program specifically addresses existing wells that are used for underground injection of motor-vehicle waste. To help determine whether a well is in an OSGWA, the Nevada Division of Environmental Protection needs statewide information on depth to water and the water table, which partly control the susceptibility of ground water to contamination and contaminant transport. This report describes a study that used available maps and data to create statewide maps of water-table and depth-to-water contours and surfaces, assessed temporal changes in water-table levels, and characterized water-table gradients in selected areas of Nevada. A literature search of published water-table and depth-to-water contours produced maps of varying detail and scope in 104 reports published from 1948 to 2004. Where multiple maps covered the same area, criteria were used to select the most recent, detailed maps that covered the largest area and had plotted control points. These selection criteria resulted in water-table and depth-to-water contours that are based on data collected from 1947 to 2004 being selected from 39 reports. If not already available digitally, contours and control points were digitized from selected maps, entered into a geographic information system, and combined to make a statewide map of water-table contours. Water-table surfaces were made by using inverse distance weighting to estimate the water table between contours and then gridding the estimates. Depth-to-water surfaces were made by subtracting the water-table altitude from the land-surface altitude. Water-table and depth-to-water surfaces were made for only 21 percent of Nevada because of a lack of information for 49 of 232 basins and for most consolidated-rock hydrogeologic units. Depth to water is commonly less than 50 feet beneath valley floors, 50 to 500 feet beneath alluvial fans, and more than 500 feet in some areas such as north-central and southern Nevada. In areas without water-table information, greasewood and mapped ground-water discharge areas are good indicators of depth to water less than 100 feet. The average difference between measured depth to water and depth to water estimated from surfaces was 90 feet. More recent and detailed information may be needed than that presented in this report to evaluate a specific site. Temporal changes in water-table levels were evaluated for 1,981 wells with 10 or more years between the first depth-to-water measurement and last measurement made since 1990. The greatest increases in depth to water occurred where the first measurement was less than 200 feet, where the time between first and last measurements was 40 years or less, and for wells between 100 and 600 feet deep. These characteristics describe production wells where ground water is fairly shallow in recently developing areas such as the Las Vegas and Reno metropolitan areas. In basins with little pumping, 90 percent of the changes during the past 100 years are within ?20 feet, which is about the natural variation in the water table due to changes in the climate and recharge. Gradients in unconsolidated sediments of the Great Basin are generally steep near mountain fronts, shallow beneath valley floors, and depend on variables such as the horizontal hydraulic conductivity of adjacent consolidated rocks and recharge. Gradients beneath alluvial fans and valley floors at 58 sites were correlated with selected variables to identify those variables that are statistically related. Water-table measurements at three sites were used to characterize the water table between the valley floor and consolidated rock. Water-table gradients beneath alluvial fan

Halocarbons as Halon Replacements. Volume 1. Technology Review and Initiation

DTIC Science & Technology

1991-03-01

gases is usually accomplished by packed bed or plate-tower scrubbers . In some cases Venturi scrubbers are used for simultaneous removal of 95 TABLE 24...packed bed or plate-tower scrubbers to lower emissions to acceptable levels. When water is used as the scrubbing liquor, the blowdown stream is acidic...blowdown rates and makeup water. Because of these acidic conditions, the scrubber must be lined with an acid-resistant material. A highly basic

WTAQ version 2-A computer program for analysis of aquifer tests in confined and water-table aquifers with alternative representations of drainage from the unsaturated zone

USGS Publications Warehouse

Barlow, Paul M.; Moench, Allen F.

2011-01-01

The computer program WTAQ simulates axial-symmetric flow to a well pumping from a confined or unconfined (water-table) aquifer. WTAQ calculates dimensionless or dimensional drawdowns that can be used with measured drawdown data from aquifer tests to estimate aquifer hydraulic properties. Version 2 of the program, which is described in this report, provides an alternative analytical representation of drainage to water-table aquifers from the unsaturated zone than that which was available in the initial versions of the code. The revised drainage model explicitly accounts for hydraulic characteristics of the unsaturated zone, specifically, the moisture retention and relative hydraulic conductivity of the soil. The revised program also retains the original conceptualizations of drainage from the unsaturated zone that were available with version 1 of the program to provide alternative approaches to simulate the drainage process. Version 2 of the program includes all other simulation capabilities of the first versions, including partial penetration of the pumped well and of observation wells and piezometers, well-bore storage and skin effects at the pumped well, and delayed drawdown response of observation wells and piezometers.

Effect of irrigation water salinity and sodicity and water table position on water table chemistry beneath Atriplex lentiformis and Hordeum marinum

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

Browning, L.S.; Bauder, J.W.; Phelps, S.D.

2006-04-15

Coal bed methane (CBM) extraction in Montana and Wyoming's Powder River Basin (PRB) produces large quantities of modestly saline-sodic water. This study assessed effects of irrigation water quality and water table position on water chemistry of closed columns, simulating a perched or a shallow water table. The experiment assessed the potential salt loading in areas where shallow or perched water tables prevent leaching or where artificial drainage is not possible. Water tables were established in sand filled PVC columns at 0.38, 0.76, and1.14 m below the surface, after which columns were planted to one of three species, two halophytic Atriplexmore » spp. and Hordeum marinum Huds. (maritime barley), a glycophyte. As results for the two Atriplex ssp. did not differ much, only results from Atriplex lentiformis (Torn) S. Wats. (big saltbush) and H. marinum are presented. Irrigation water representing one of two irrigation sources was used: Powder River (PR) (electrolytic conductivity (EC) = 0.19 Sm{sup -1}, sodium adsorption ratio (SAR) = 3.5) or CBM water (EC = 0.35 Sm-1, SAR = 10.5). Continuous irrigation with CBM and PR water led to salt loading over time, the extent being proportional to the salinity and sodicity of applied water. Water in columns planted to A. lentiformis with water tables maintained at 0.38 m depth had greater EC and SAR values than those with 0.76 and 1.14 m water table positions. Elevated EC and SAR values most likely reflect the shallow rooted nature of A. lentiformis, which resulted in enhanced ET with the water table close to the soil surface.« less

Impact of drugs on the environment: state of play, risks, evaluation, communication.

PubMed

Defarges, Thierry Moreau; Guerbet, Michel; Massol, Jacques

2011-01-01

The aim of this Round Table was to perform an initial assessment of the state of play of the impact of drugs on the environment. Demographic growth throughout the world and drug consumption which is constantly on the increase result in an ever increasing presence of medicinal substances in the various compartments (air, water, soil) with potential repercussions on the environment and on health. For the first time, the Giens pharmacology workshop have scheduled this topic outside the conventional sphere of action of Giens. A very high level of interest in this topic came forward both from the members of the round table and the listeners and it is certain that the round table opens the door to new initiatives for a subject about which there is still little knowledge. The following issues were therefore successively addressed: the fragmentation of the knowledge about the subject and its deficiencies concerning the impact on health, both of the wastes as a whole and that of specific drugs, the performances of the water treatment methods, the sources of pollution, the environmental impact, the lines of regulatory development, the impact on the environment and health and the training programmes to be set up among all protagonists, both professional and in the general public. © 2011 Société Française de Pharmacologie et de Thérapeutique.

TOPMODEL simulations of streamflow and depth to water table in Fishing Brook Watershed, New York, 2007-09

USGS Publications Warehouse

Nystrom, Elizabeth A.; Burns, Douglas A.

2011-01-01

TOPMODEL uses a topographic wetness index computed from surface-elevation data to simulate streamflow and subsurface-saturation state, represented by the saturation deficit. Depth to water table was computed from simulated saturation-deficit values using computed soil properties. In the Fishing Brook Watershed, TOPMODEL was calibrated to the natural logarithm of streamflow at the study area outlet and depth to water table at Sixmile Wetland using a combined multiple-objective function. Runoff and depth to water table responded differently to some of the model parameters, and the combined multiple-objective function balanced the goodness-of-fit of the model realizations with respect to these parameters. Results show that TOPMODEL reasonably simulated runoff and depth to water table during the study period. The simulated runoff had a Nash-Sutcliffe efficiency of 0.738, but the model underpredicted total runoff by 14 percent. Depth to water table computed from simulated saturation-deficit values matched observed water-table depth moderately well; the root mean squared error of absolute depth to water table was 91 millimeters (mm), compared to the mean observed depth to water table of 205 mm. The correlation coefficient for temporal depth-to-water-table fluctuations was 0.624. The variability of the TOPMODEL simulations was assessed using prediction intervals grouped using the combined multiple-objective function. The calibrated TOPMODEL results for the entire study area were applied to several subwatersheds within the study area using computed hydrogeomorphic properties of the subwatersheds.

Manipulative lowering of the water table during summer does not affect CO2 emissions and uptake in a fen in Germany.

PubMed

Muhr, Jan; Höhle, Juliane; Otieno, Dennis O; Borken, Werner

2011-03-01

We simulated the effect of prolonged dry summer periods by lowering the water table on three manipulation plots (D(1-3)) in a minerotrophic fen in southeastern Germany in three years (2006-2008). The water table at this site was lowered by drainage and by excluding precipitation; three nonmanipulated control plots (C(1-3)) served as a reference. We found no significant differences in soil respiration (R(Soil)), gross primary production (GPP), or aboveground respiration (R(AG)) between the C(1-3) and D(1-3) plots in any of the measurement years. The water table on the control plots was naturally low, with a median water table (2006-2008) of 8 cm below the surface, and even lower during summer when respiratory activity was highest, with median values (C(1-3)) between 11 and 19 cm below the surface. If it is assumed that oxygen availability in the uppermost 10 cm was not limited by the location of the water table, manipulative lowering of the water table most likely increased oxygen availability only in deeper peat layers where we expect R(Soil) to be limited by poor substrate quality rather than anoxia. This could explain the lack of a manipulation effect. In a second approach, we estimated the influence of the water table on R(Soil) irrespective of treatment. The results showed a significant correlation between R(Soil) and water table, but with R(Soil) decreasing at lower water tables rather than increasing. We thus conclude that decomposition in the litter layer is not limited by waterlogging in summer, and deeper peat layers bear no significant decomposition potential due to poor substrate quality. Consequently, we do not expect enhanced C losses from this site due to increasing frequency of dry summers. Assimilation and respiration of aboveground vegetation were not affected by water table fluctuations between 10 and >60 cm depth, indicating the lack of stress resulting from either anoxia (high water table) or drought (low water table).

40 CFR Appendix - Tables to Part 132

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 23 2013-07-01 2013-07-01 false Tables to Part 132 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM Application of part 132 requirements in Great Lakes States and Tribes. Pt. 132, Tables Tables to Part 132 Table 1—Acute Water Quality...

Predicting water table response to rainfall events, central Florida.

PubMed

van Gaalen, J F; Kruse, S; Lafrenz, W B; Burroughs, S M

2013-01-01

A rise in water table in response to a rainfall event is a complex function of permeability, specific yield, antecedent soil-water conditions, water table level, evapotranspiration, vegetation, lateral groundwater flow, and rainfall volume and intensity. Predictions of water table response, however, commonly assume a linear relationship between response and rainfall based on cumulative analysis of water level and rainfall logs. By identifying individual rainfall events and responses, we examine how the response/rainfall ratio varies as a function of antecedent water table level (stage) and rainfall event size. For wells in wetlands and uplands in central Florida, incorporating stage and event size improves forecasting of water table rise by more than 30%, based on 10 years of data. At the 11 sites studied, the water table is generally least responsive to rainfall at smallest and largest rainfall event sizes and at lower stages. At most sites the minimum amount of rainfall required to induce a rise in water table is fairly uniform when the water table is within 50 to 100 cm of land surface. Below this depth, the minimum typically gradually increases with depth. These observations can be qualitatively explained by unsaturated zone flow processes. Overall, response/rainfall ratios are higher in wetlands and lower in uplands, presumably reflecting lower specific yields and greater lateral influx in wetland sites. Pronounced depth variations in rainfall/response ratios appear to correlate with soil layer boundaries, where corroborating data are available. © 2012, The Author(s). Groundwater © 2012, National Ground Water Association.

Ammonia Volatilization Losses from Paddy Fields under Controlled Irrigation with Different Drainage Treatments

PubMed Central

He, Yupu; Yang, Shihong; Wang, Yijiang

2014-01-01

The effect of controlled drainage (CD) on ammonia volatilization (AV) losses from paddy fields under controlled irrigation (CI) was investigated by managing water table control levels using a lysimeter. Three drainage treatments were implemented, namely, controlled water table depth 1 (CWT1), controlled water table depth 2 (CWT2), and controlled water table depth 3 (CWT3). As the water table control levels increased, irrigation water volumes in the CI paddy fields decreased. AV losses from paddy fields reduced due to the increases in water table control levels. Seasonal AV losses from CWT1, CWT2, and CWT3 were 59.8, 56.7, and 53.0 kg N ha−1, respectively. AV losses from CWT3 were 13.1% and 8.4% lower than those from CWT1 and CWT2, respectively. A significant difference in the seasonal AV losses was confirmed between CWT1 and CWT3. Less weekly AV losses followed by TF and PF were also observed as the water table control levels increased. The application of CD by increasing water table control levels to a suitable level could effectively reduce irrigation water volumes and AV losses from CI paddy fields. The combination of CI and CD may be a feasible water management method of reducing AV losses from paddy fields. PMID:24741349

Ammonia volatilization losses from paddy fields under controlled irrigation with different drainage treatments.

PubMed

He, Yupu; Yang, Shihong; Xu, Junzeng; Wang, Yijiang; Peng, Shizhang

2014-01-01

The effect of controlled drainage (CD) on ammonia volatilization (AV) losses from paddy fields under controlled irrigation (CI) was investigated by managing water table control levels using a lysimeter. Three drainage treatments were implemented, namely, controlled water table depth 1 (CWT1), controlled water table depth 2 (CWT2), and controlled water table depth 3 (CWT3). As the water table control levels increased, irrigation water volumes in the CI paddy fields decreased. AV losses from paddy fields reduced due to the increases in water table control levels. Seasonal AV losses from CWT1, CWT2, and CWT3 were 59.8, 56.7, and 53.0 kg N ha(-1), respectively. AV losses from CWT3 were 13.1% and 8.4% lower than those from CWT1 and CWT2, respectively. A significant difference in the seasonal AV losses was confirmed between CWT1 and CWT3. Less weekly AV losses followed by TF and PF were also observed as the water table control levels increased. The application of CD by increasing water table control levels to a suitable level could effectively reduce irrigation water volumes and AV losses from CI paddy fields. The combination of CI and CD may be a feasible water management method of reducing AV losses from paddy fields.

Application of GPS and Near-Surface Geophysical Methods to Evaluate Differences Between Agricultural Test Plots

USDA-ARS?s Scientific Manuscript database

A field research facility with two pairs of replicated agricultural test plots (four total) was established at a location in northwest Ohio during 2005 for the purpose of studying water table management strategies. Initial efforts at this field research facility were devoted to evaluating difference...

Modeling regional initiation of rainfall-induced shallow landslides in the eastern Umbria Region of central Italy

USGS Publications Warehouse

Salciarini, D.; Godt, J.W.; Savage, W.Z.; Conversini, P.; Baum, R.L.; Michael, J.A.

2006-01-01

We model the rainfall-induced initiation of shallow landslides over a broad region using a deterministic approach, the Transient Rainfall Infiltration and Grid-based Slope-stability (TRIGRS) model that couples an infinite-slope stability analysis with a one-dimensional analytical solution for transient pore pressure response to rainfall infiltration. This model permits the evaluation of regional shallow landslide susceptibility in a Geographic Information System framework, and we use it to analyze susceptibility to shallow landslides in an area in the eastern Umbria Region of central Italy. As shown on a landslide inventory map produced by the Italian National Research Council, the area has been affected in the past by shallow landslides, many of which have transformed into debris flows. Input data for the TRIGRS model include time-varying rainfall, topographic slope, colluvial thickness, initial water table depth, and material strength and hydraulic properties. Because of a paucity of input data, we focus on parametric analyses to calibrate and test the model and show the effect of variation in material properties and initial water table conditions on the distribution of simulated instability in the study area in response to realistic rainfall. Comparing the results with the shallow landslide inventory map, we find more than 80% agreement between predicted shallow landslide susceptibility and the inventory, despite the paucity of input data.

Changes in vegetative communities and water table dynamics following timber harvesting in small headwater streams

Treesearch

B. Choi; J.C. Dewey; J. A. Hatten; A.W. Ezell; Z. Fan

2012-01-01

In order to better understand the relationship between vegetation communities and water table in the uppermost portions (ephemeral–intermittent streams) of headwater systems, seasonal plot-based field characterizations of vegetation were used in conjunction with monthly water table measurements. Vegetation, soils, and water table data were examined to determine...

Dynamics of water-table fluctuations in an upland between two prairie-pothole wetlands in North Dakota

USGS Publications Warehouse

Rosenberry, Donald O.; Winter, Thomas C.

1997-01-01

Data from a string of instrumented wells located on an upland of 55 m width between two wetlands in central North Dakota, USA, indicated frequent changes in water-table configuration following wet and dry periods during 5 years of investigation. A seasonal wetland is situated about 1.5 m higher than a nearby semipermanent wetland, suggesting an average ground water-table gradient of 0.02. However, water had the potential to flow as ground water from the upper to the lower wetland during only a few instances. A water-table trough adjacent to the lower semipermanent wetland was the most common water-table configuration during the first 4 years of the study, but it is likely that severe drought during those years contributed to the longevity and extent of the water-table trough. Water-table mounds that formed in response to rainfall events caused reversals of direction of flow that frequently modified the more dominant water-table trough during the severe drought. Rapid and large water-table rise to near land surface in response to intense rainfall was aided by the thick capillary fringe. One of the wettest summers on record ended the severe drought during the last year of the study, and caused a larger-scale water-table mound to form between the two wetlands. The mound was short in duration because it was overwhelmed by rising stage of the higher seasonal wetland which spilled into the lower wetland. Evapotranspiration was responsible for generating the water-table trough that formed between the two wetlands. Estimation of evapotranspiration based on diurnal fluctuations in wells yielded rates that averaged 3–5 mm day−1. On many occasions water levels in wells closer to the semipermanent wetland indicated a direction of flow that was different from the direction indicated by water levels in wells farther from the wetland. Misinterpretation of direction and magnitude of gradients between ground water and wetlands could result from poorly placed or too few observation wells, and also from infrequent measurement of water levels in wells.

Beaver Mediated Water Table Dynamics in Mountain Peatlands

NASA Astrophysics Data System (ADS)

Karran, D. J.; Westbrook, C.; Bedard-Haughn, A.

2016-12-01

Water table dynamics play an important role in the ecological and biogeochemical processes that regulate carbon and water storage in peatlands. Beaver are common in these habitats and the dams they build have been shown to raise water tables in other environments. However, the impact of beaver dams in peatlands, where water tables rest close to the surface, has yet to be determined. We monitored a network of 50 shallow wells in a Canadian Rocky Mountain peatland for 6 years. During this period, a beaver colony was maintaining a number of beaver ponds for four years until a flood event removed the colony from the area and breached some of the dams. Two more years of data were collected after the flood event to assess whether the dams enhanced groundwater storage. Beaver dams raised water tables just as they do in other environments. Furthermore, water tables within 100 meters of beaver dams were more stable than those further away and water table stability overall was greater before the flood event. Our results suggest the presence/absence of beaver in peatlands has implications for groundwater water storage and overall system function.

40 CFR Table 8 to Subpart Xxxx of... - Initial Compliance With the Emission

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial Compliance With the Emission 8 Table 8 to Subpart XXXX of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED.... XXXX, Table 8 Table 8 to Subpart XXXX of Part 63—Initial Compliance With the Emission As stated in § 63...

A time series approach to inferring groundwater recharge using the water table fluctuation method

NASA Astrophysics Data System (ADS)

Crosbie, Russell S.; Binning, Philip; Kalma, Jetse D.

2005-01-01

The water table fluctuation method for determining recharge from precipitation and water table measurements was originally developed on an event basis. Here a new multievent time series approach is presented for inferring groundwater recharge from long-term water table and precipitation records. Additional new features are the incorporation of a variable specific yield based upon the soil moisture retention curve, proper accounting for the Lisse effect on the water table, and the incorporation of aquifer drainage so that recharge can be detected even if the water table does not rise. A methodology for filtering noise and non-rainfall-related water table fluctuations is also presented. The model has been applied to 2 years of field data collected in the Tomago sand beds near Newcastle, Australia. It is shown that gross recharge estimates are very sensitive to time step size and specific yield. Properly accounting for the Lisse effect is also important to determining recharge.

40 CFR Table 7 to Subpart Xxxx of... - Initial Compliance With the Emission Limits for Tire Cord Production Affected Sources

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial Compliance With the Emission Limits for Tire Cord Production Affected Sources 7 Table 7 to Subpart XXXX of Part 63 Protection of... Pollutants: Rubber Tire Manufacturing Pt. 63, Subpt. XXXX, Table 7 Table 7 to Subpart XXXX of Part 63—Initial...

40 CFR Table 19 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units 19 Table 19 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 19 Table 19 to Subpart UUU of Part 63—Initial Compliance With Organic...

40 CFR Table 26 to Subpart Uuu of... - Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units 26 Table 26 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 26 Table 26 to Subpart UUU of Part 63—Initial Compliance With Inorganic...

40 CFR Table 12 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units 12 Table 12 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 12 Table 12 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 12 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units 12 Table 12 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 12 Table 12 to Subpart UUU of Part 63—Initial Compliance With Organic...

40 CFR Table 33 to Subpart Uuu of... - Initial Compliance With HAP Emission Limits for Sulfur Recovery Units

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Initial Compliance With HAP Emission Limits for Sulfur Recovery Units 33 Table 33 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 33 Table 33 to Subpart UUU of Part 63—Initial Compliance With HAP...

40 CFR Table 33 to Subpart Uuu of... - Initial Compliance With HAP Emission Limits for Sulfur Recovery Units

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Initial Compliance With HAP Emission Limits for Sulfur Recovery Units 33 Table 33 to Subpart UUU of Part 63 Protection of Environment..., Subpt. UUU, Table 33 Table 33 to Subpart UUU of Part 63—Initial Compliance With HAP Emission Limits for...

40 CFR Table 26 to Subpart Uuu of... - Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units 26 Table 26 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 26 Table 26 to Subpart UUU of Part 63—Initial Compliance With Inorganic...

40 CFR Table 19 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units 19 Table 19 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 19 Table 19 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 12 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units 12 Table 12 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 12 Table 12 to Subpart UUU of Part 63—Initial Compliance With Organic...

40 CFR Table 33 to Subpart Uuu of... - Initial Compliance With HAP Emission Limits for Sulfur Recovery Units

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Initial Compliance With HAP Emission Limits for Sulfur Recovery Units 33 Table 33 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 33 Table 33 to Subpart UUU of Part 63—Initial Compliance With HAP...

40 CFR Table 38 to Subpart Uuu of... - Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines 38 Table 38 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 38 Table 38 to Subpart UUU of Part 63—Initial Compliance With Work...

40 CFR Table 26 to Subpart Uuu of... - Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units 26 Table 26 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 26 Table 26 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 38 to Subpart Uuu of... - Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines 38 Table 38 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 38 Table 38 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 26 to Subpart Uuu of... - Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units 26 Table 26 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 26 Table 26 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 38 to Subpart Uuu of... - Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines 38 Table 38 to Subpart UUU of Part 63 Protection of... Units Pt. 63, Subpt. UUU, Table 38 Table 38 to Subpart UUU of Part 63—Initial Compliance With Work...

40 CFR Table 33 to Subpart Uuu of... - Initial Compliance With HAP Emission Limits for Sulfur Recovery Units

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial Compliance With HAP Emission Limits for Sulfur Recovery Units 33 Table 33 to Subpart UUU of Part 63 Protection of Environment..., Subpt. UUU, Table 33 Table 33 to Subpart UUU of Part 63—Initial Compliance With HAP Emission Limits for...

40 CFR Table 38 to Subpart Uuu of... - Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines 38 Table 38 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 38 Table 38 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 12 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units 12 Table 12 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 12 Table 12 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 26 to Subpart Uuu of... - Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Initial Compliance With Inorganic HAP Emission Limits for Catalytic Reforming Units 26 Table 26 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 26 Table 26 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 12 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units 12 Table 12 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 12 Table 12 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 19 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units 19 Table 19 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 19 Table 19 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 38 to Subpart Uuu of... - Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Initial Compliance With Work Practice Standards for HAP Emissions From Bypass Lines 38 Table 38 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 38 Table 38 to Subpart UUU of Part 63—Initial Compliance...

40 CFR Table 33 to Subpart Uuu of... - Initial Compliance With HAP Emission Limits for Sulfur Recovery Units

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Initial Compliance With HAP Emission Limits for Sulfur Recovery Units 33 Table 33 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 33 Table 33 to Subpart UUU of Part 63—Initial Compliance With HAP...

40 CFR Table 19 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Initial Compliance With Organic HAP Emission Limits for Catalytic Reforming Units 19 Table 19 to Subpart UUU of Part 63 Protection of... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 19 Table 19 to Subpart UUU of Part 63—Initial Compliance...

Incorporating Peatland Plant Communities into the Enzymic 'Latch' Hypothesis: Can Vegetation Influence Carbon Storage Mechanisms?

NASA Astrophysics Data System (ADS)

Romanowicz, K. J.; Daniels, A. L.; Potvin, L. R.; Kane, E. S.; Kolka, R. K.; Chimner, R. A.; Lilleskov, E. A.

2012-12-01

High water table conditions in peatland ecosystems are known to favor plant production over decomposition and carbon is stored. Dominant plant communities change in response to water table but little is know of how these changes affect belowground carbon storage. One hypothesis known as the enzymic 'latch' proposed by Freeman et al. suggests that oxygen limitations due to high water table conditions inhibit microorganisms from synthesizing specific extracellular enzymes essential for carbon and nutrient mineralization, allowing carbon to be stored as decomposition is reduced. Yet, this hypothesis excludes plant community interactions on carbon storage. We hypothesize that the dominant vascular plant communities, sedges and ericaceous shrubs, will have inherently different effects on peatland carbon storage, especially in response to declines in water table. Sedges greatly increase in abundance following water table decline and create extensive carbon oxidation and mineralization hotspots through the production of deep roots with aerenchyma (air channels in roots). Increased oxidation may enhance aerobic microbial activity including increased enzyme activity, leading to peat subsidence and carbon loss. In contrast, ericaceous shrubs utilize enzymatically active ericoid mycorrhizal fungi that suppress free-living heterotrophs, promoting decreased carbon mineralization by mediating changes in rhizosphere microbial communities and enzyme activity regardless of water table declines. Beginning May 2010, bog monoliths were harvested, housed in mesocosm chambers, and manipulated into three vegetation treatments: unmanipulated (+sedge, +Ericaceae), sedge (+sedge, -Ericaceae), and Ericaceae (-sedge, +Ericaceae). Following vegetation manipulations, two distinct water table manipulations targeting water table seasonal profiles were implemented: (low intra-seasonal variability, higher mean water table; high intra-seasonal variability, lower mean water table). In 2012, peat cores are being assayed monthly from June - October for two oxidase enzyme activities (phenol oxidase, peroxidase) and four hydrolase enzyme activities (β-glucosidase, chitinase, cellobiohydrolase, and acid-phosphatase). Early season assays (June and July) where water table treatments did not significantly vary showed trends of decreasing oxidase activities while hydrolase activities increased. These preliminary results show no significant differences between vegetation treatments but as the season progresses (August - October), water table levels between high and low treatments will continue to experience greater dissimilarities. These water table declines within sedge and ericaceous shrub communities may have opposing effects on rhizosphere extracellular enzyme activities indicating plant communities may significantly influence belowground carbon storage mechanisms in ways not previously considered in peatland ecosystems.

40 CFR Table 5 to Subpart Kkkkk of... - Initial Compliance with Emission Limitations and Work Practice Standards

Code of Federal Regulations, 2010 CFR

2010-07-01

... Limitations and Work Practice Standards 5 Table 5 to Subpart KKKKK of Part 63 Protection of Environment... Pollutants for Clay Ceramics Manufacturing Pt. 63, Subpt. KKKKK, Table 5 Table 5 to Subpart KKKKK of Part 63... table: For each . . . For the following . . . You have demonstrated initial compliance if . . . 1. New...

40 CFR Table 5 to Subpart Kkkkk of... - Initial Compliance with Emission Limitations and Work Practice Standards

Code of Federal Regulations, 2011 CFR

2011-07-01

... Limitations and Work Practice Standards 5 Table 5 to Subpart KKKKK of Part 63 Protection of Environment... Pollutants for Clay Ceramics Manufacturing Pt. 63, Subpt. KKKKK, Table 5 Table 5 to Subpart KKKKK of Part 63... table: For each . . . For the following . . . You have demonstrated initial compliance if . . . 1. New...

40 CFR Table 5 to Subpart Kkkkk of... - Initial Compliance with Emission Limitations and Work Practice Standards

Code of Federal Regulations, 2014 CFR

2014-07-01

... Limitations and Work Practice Standards 5 Table 5 to Subpart KKKKK of Part 63 Protection of Environment... Pollutants for Clay Ceramics Manufacturing Pt. 63, Subpt. KKKKK, Table 5 Table 5 to Subpart KKKKK of Part 63... table: For each . . . For the following . . . You have demonstrated initial compliance if . . . 1. New...

40 CFR Table 5 to Subpart Kkkkk of... - Initial Compliance with Emission Limitations and Work Practice Standards

Code of Federal Regulations, 2013 CFR

2013-07-01

... Limitations and Work Practice Standards 5 Table 5 to Subpart KKKKK of Part 63 Protection of Environment... Pollutants for Clay Ceramics Manufacturing Pt. 63, Subpt. KKKKK, Table 5 Table 5 to Subpart KKKKK of Part 63... table: For each . . . For the following . . . You have demonstrated initial compliance if . . . 1. New...

40 CFR Table 5 to Subpart Kkkkk of... - Initial Compliance with Emission Limitations and Work Practice Standards

Code of Federal Regulations, 2012 CFR

2012-07-01

... Limitations and Work Practice Standards 5 Table 5 to Subpart KKKKK of Part 63 Protection of Environment... Pollutants for Clay Ceramics Manufacturing Pt. 63, Subpt. KKKKK, Table 5 Table 5 to Subpart KKKKK of Part 63... table: For each . . . For the following . . . You have demonstrated initial compliance if . . . 1. New...

Improvements to a global-scale groundwater model to estimate the water table across New Zealand

NASA Astrophysics Data System (ADS)

Westerhoff, Rogier; Miguez-Macho, Gonzalo; White, Paul

2017-04-01

Groundwater models at the global scale have become increasingly important in recent years to assess the effects of climate change and groundwater depletion. However, these global-scale models are typically not used for studies at the catchment scale, because they are simplified and too spatially coarse. In this study, we improved the global-scale Equilibrium Water Table (EWT) model, so it could better assess water table depth and water table elevation at the national scale for New Zealand. The resulting National Water Table (NWT) model used improved input data (i.e., national input data of terrain, geology, and recharge) and model equations (e.g., a hydraulic conductivity - depth relation). The NWT model produced maps of the water table that identified the main alluvial aquifers with fine spatial detail. Two regional case studies at the catchment scale demonstrated excellent correlation between the water table elevation and observations of hydraulic head. The NWT water tables are an improved water table estimation over the EWT model. In two case studies the NWT model provided a better approximation to observed water table for deep aquifers and the improved resolution of the model provided the capability to fill the gaps in data-sparse areas. This national model calculated water table depth and elevation across regional jurisdictions. Therefore, the model is relevant where trans-boundary issues, such as source protection and catchment boundary definition, occur. The NWT model also has the potential to constrain the uncertainty of catchment-scale models, particularly where data are sparse. Shortcomings of the NWT model are caused by the inaccuracy of input data and the simplified model properties. Future research should focus on improved estimation of input data (e.g., hydraulic conductivity and terrain). However, more advanced catchment-scale groundwater models should be used where groundwater flow is dominated by confining layers and fractures.

Carbon cycling responses to a water table drawdown and decadal vegetation changes in a bog

NASA Astrophysics Data System (ADS)

Talbot, J.; Roulet, N. T.

2009-12-01

The quantity of carbon stored in peat depends on the imbalance between production and decomposition of organic matter. This imbalance is mainly controlled by the wetness of the peatland, usually described by the water table depth. However, long-term processes resulting from hydrological changes, such as vegetation succession, also play a major role in the biogeochemistry of peatlands. Previous studies have looked at the impact of a water table lowering on carbon fluxes in different types of peatlands. However, most of these studies were conducted within a time frame that did not allow the examination of vegetation changes due to the water table lowering. We conducted a study along a drainage gradient resulting from the digging of a drainage ditch 85 years ago in a portion of the Mer Bleue bog, located near Ottawa, Canada. According to water table reconstructions based on testate amoeba, the drainage dropped the water table by approximately 18 cm. On the upslope side of the ditch, the water table partly recovered and the vegetation changed only marginally. However, on the downslope side of the ditch, the water table stayed persistently lower and trees established (Larix and Betula). The importance of Sphagnum decreased with a lower water table, and evergreen shrubs were replaced by deciduous shrubs. The water table drop and subsequent vegetation changes had combined and individual effects on the carbon functioning of the peatland. Methane fluxes decreased because of the water table lowering, but were not affected by vegetation changes, whereas respiration and net ecosystem productivity were affected by both. The carbon storage of the system increased because of an increase in plant biomass, but the long-term carbon storage as peat decreased. The inclusion of the feedback effect that vegetation has on the carbon functioning of a peatland when a disturbance occurs is crucial to simulate the long-term carbon balance of this ecosystem.

40 CFR Table 2 to Subpart Kkkkk of... - Operating Limits

Code of Federal Regulations, 2010 CFR

2010-07-01

... stack. 2. Kiln equipped with a DIFF or DLS/FF a. If you use a bag leak detection system, initiate corrective action within 1 hour of a bag leak detection system alarm and complete corrective actions in... to the scrubber water, maintain the average scrubber chemical feed rate for each 3-hour block period...

Methane emissions from boreal peatlands in a changing climate: Quantifying the sensitivity of methane fluxes to experimental manipulations of water table and soil temperature regimes in an Alaskan boreal fen

NASA Astrophysics Data System (ADS)

Treat, C. C.; Turetsky, M.; Harden, J.; McGuire, A.

2006-12-01

Peatlands cover only 3-5 % of the world's land surface but store 30 % of the world's soil carbon (C) pool. Peatlands currently are thought to function globally as a net sink for atmospheric CO2, sequestering approximately 76 Tg (1012 g) C yr-1. However, peatlands also function as a net source of atmospheric CH4. Approximately 25% of the 270 Tg CH4 yr-1 emitted from natural sources are emitted from northern wetlands. Methane production (methanogenesis) and consumption (methane oxidation) in peatlands are sensitive to both fluctuations in soil moisture and temperature. Boreal regions already are experiencing rapid changes in climate, including longer and drier growing seasons and the degradation of permafrost. Changes in peat environments in response to these climate changes could have significant implications for CH4 emissions to the atmosphere, and thus the radiative forcing of high latitude regions. In 2005, we initiated a large scale in situ climate experiment in a moderately rich fen near the Bonanza Creek LTER site in central Alaska (APEX: www.apex.msu.edu). The goal of our project is to understand vegetation and C cycling processes under altered water table and soil thermal regimes. We established three water table plots (control, raised, lowered), each about 120 m2 in area, using drainage ditches to lower the water table by 5-10 cm and solar powered pumps to raise the water table by about 5-15 cm. Within each water table plot, we constructed replicate open top chambers (OTCs) to passively increase surface temperatures by about 1 ° C. We used static chambers and gas chromatography to quantify methane fluxes at each water table x soil warming plot through the growing seasons of 2005 and 2006. Additionally, we quantified seasonal CH4 fluxes along an adjacent moisture gradient that included four distinct soil moisture and vegetation zones, including a moderately rich fen (APEX site), an emergent macrophyte marsh, a shrubby permafrost fen, and a black spruce permafrost forest. Our results thus far show that methane fluxes varied by a warming x water table interaction across our experimental treatments (Proc Mixed SAS Repeated Measures ANOVA; F2,8=4.07; p=0.05), with the largest methane fluxes in the warm, wet peatland plots and the lowest methane fluxes in the unwarmed, dry peatland plots. Sites along the moisture gradient transitioned from methane sources in the rich fen site (APEX plots) to small sinks of CH4 in the permafrost forest under drying soil moisture conditions. Our soil climate manipulations allow us to quantify interactions among biogeophysical variables that control CH4 emissions from peatlands. Our coupled experimental and gradient based measurements allow us to explore controls on microbial populations and methane emissions across a wider range of terrestrial boreal environments. This work so far shows that methane cycling in interior Alaskan ecosystems is extremely sensitive to soil climate conditions, and that the fate of methane emissions from high latitudes will be affected primarily by changes in precipitation and soil drainage that control water table position in peatlands and permafrost ecosystems.

Northern part, Ten Mile and Taunton River basins

USGS Publications Warehouse

Williams, John R.; Willey, Richard E.

1967-01-01

This report is one of two prepared by the Geological Survey for the Water Resources Commission. The principal purpose of this report is to make available the basic data on which the other, a map showing availability of ground water, is based. This basic-data report also can be used by engineers, planners, and others interested in or responsible for water-resources planning to determine the materials to be encountered (tables 3 and 4) and the yields which may be obtained from wells and test holes (tables 1 and 2) in the stratified sand and gravel that are the principal source of ground water and in bedrock. Partial and complete chemical analyses (tables 7 and 8) of these test holes and of some privately-owned wells provide information on the general quality of the water for domestic and other uses. A tabulation of existing municipal supplies, their capacity, production (table 5), and chemical quality of the water (table 6) may be used for regional planning purposes. Water-level measurements (figure 1) can be used to determine the annual fluctuations of the water table in certain types of materials. Seismic work (table 9) in the Canoe River valley, Norton, and test drilling with a power augur (tables 2 and 4) were done for the Geological Survey as  part of the investigation.

Water-table decline in the south-central Great Basin during the Quaternary Period; implications for toxic-waste disposal

USGS Publications Warehouse

Winograd, I.J.; Szabo, B. J.

1986-01-01

The distribution of vein calcite, tufa, and other features indicative of paleo-groundwater discharge, indicates that during the early to middle Pleistocene, the water table at Ash Meadows, in the Amargosa Desert, Nevada, and at Furnace Creek Wash, in east-central Death Valley, California, was tens to hundreds of meters above the modern water table, and that groundwater discharge occurred up to 18 km up-the-hydraulic gradient from modern discharge areas. Uranium series dating of the calcitic veins permits calculation of rates of apparent water table decline; rates of 0.02 to 0.08 m/1000 yr are indicated for Ash meadows and 0.2 to 0.6 m/1000 yr for Furnace Creek Wash. The rates for Furnace Creek Wash closely match a published estimate of vertical crustal offset for this area, suggesting that tectonism is a major cause for the displacement observed. In general, displacements of the paleo-water table probably reflect a combination of: (a) tectonic uplift of vein calcite and tufa, unaccompanied by a change in water table altitude; (b) decline in water table altitude in response to tectonic depression of areas adjacent to dated veins and associated tufa; (c) decline in water table altitude in response to increasing aridity caused by major uplift of the Sierra Nevada and Transverse Ranges during the Quaternary; and (d) decline in water altitude in response to erosion triggered by increasing aridity and/or tectonism. A synthesis of geohydrologic, neotectonic, and paleoclimatologic information with the vein-calcite data permits the inference that the water table in the south-central Great Basin progressively lowered throughout the Quaternary. This inference is pertinent to an evaluation of the utility of thick (200-600 m) unsaturated zones of the region for isolating solidified radioactive wastes from the hydrosphere for hundreds of millenia. Wastes buried a few tens to perhaps 100 m above the modern water table--that is above possible water level rises due to future pluvial climates--are unlikely to be inundated by a rising water table in the foreseeable geologic future. (Author 's abstract)

Unconfined aquifer response to infiltration basins and shallow pump tests

NASA Astrophysics Data System (ADS)

Ostendorf, David W.; DeGroot, Don J.; Hinlein, Erich S.

2007-05-01

SummaryWe measure and model the unsteady, axisymmetric response of an unconfined aquifer to delayed, arbitrary recharge. Water table drainage follows the initial elastic aquifer response, as modeled for uniform, instantaneous recharge by Zlotnik and Ledder [Zlotnik, V., Ledder, G., 1992. Groundwater flow in a compressible unconfined aquifer with uniform circular recharge. Water Resources Research 28(6), 1619-1630] and delayed drainage by Moench [Moench, A.F., 1995. Combining the Neuman and Boulton models for flow to a well in an unconfined aquifer. Ground Water 33(3), 378-384]. We extend their analyses with a convolution integral that models the delayed response of an aquifer to infiltration from a circular infiltration basin. The basin routes the hydrograph to the water table with a decay constant dependent on a Brooks and Corey [Brooks, R.H., Corey, A.T., 1966. Properties of porous media affecting fluid flow. Journal of the Irrigation and Drainage Division ASCE 92(2), 61-88] unsaturated permeability exponent. The resulting closed form model approaches Neuman's [Neuman, S.P., 1972. Theory of flow in unconfined aquifers considering delayed response of the water table. Water Resources Research 8(4), 1031-1045] partially penetrating pump test equation for a small source radius, instantaneous, uniform drainage and a shallow screen section. Irrigation pump data at a well characterized part of the Plymouth-Carver Aquifer in southeastern Massachusetts calibrate the small source model, while infiltration data from the closed drainage system of State Route 25 calibrate the infiltration basin model. The calibrated permeability, elasticity, specific yield, and permeability exponent are plausible and consistent for the pump and infiltration data sets.

Modeling a thick unsaturated zone at San Gorgonio Pass, California: lessons learned after five years of artificial recharge

USGS Publications Warehouse

Flint, Alan L.; Ellett, Kevin M.; Christensen, Allen H.; Martin, Peter

2012-01-01

The information flow among the tasks of framework assessment, numerical modeling, model forecasting and hind casting, and system-performance monitoring is illustrated. Results provide an understanding of artificial recharge in high-altitude desert settings where large vertical distances may separate application ponds from their target aquifers.Approximately 3.8 million cubic meters of surface water was applied to spreading ponds from 2003–2007 to artificially recharge the underlying aquifer through a 200-meter thick unsaturated zone in the San Gorgonio Pass area in southern California. A study was conducted between 1997 and 2003, and a numerical model was developed to help determine the suitability of the site for artificial recharge. Ongoing monitoring results indicated that the existing model needed to be modified and recalibrated to more accurately predict artificial recharge at the site. The objective of this work was to recalibrate the model by using observation of the application rates, the rise and fall of the water level above a perching layer, and the approximate arrival time to the water table during the 5-yr monitoring period following initiation of long-term artificial recharge. Continuous monitoring of soil-matric potential, temperature, and water levels beneath the site indicated that artificial recharge reached the underlying water table between 3.75 and 4.5 yr after the initial application of the recharge water. The model was modified to allow the simulation to more adequately match the perching layer dynamics and the time of arrival at the water table. The instrumentation also showed that the lag time between changes in application of water at the surface and the response at the perching layer decreased from about 4 mo to less than 1 mo due to the wet-up of the unsaturated zone and the increase in relative permeability. The results of this study demonstrate the importance of iteratively monitoring and modeling the unsaturated zone in layered alluvial systems in the context of artificial recharge. They show that adequate geologic and hydraulic-property data on perching layers are critical to success. Continuous monitoring in the unsaturated and saturated zones beneath a site provides data to develop and constrain numerical models, better understand local unsaturated zone process, manage artificial recharge operations, and to determine the timing and volume of recoverable water for consumptive use.

Water table variability and runoff generation in an eroded peatland, South Pennines, UK

NASA Astrophysics Data System (ADS)

Daniels, S. M.; Agnew, C. T.; Allott, T. E. H.; Evans, M. G.

2008-10-01

SummaryHydrological monitoring in an eroded South Pennine peatland shows that persistent and frequent water table drawdowns occur at gully edge locations, defining a deeper and thicker acrotelm than is observed in intact peatlands (an erosional acrotelm). Antecedent water table elevation is a key control on the hydrological response to precipitation events, in particular runoff percent, the timing of peak discharges and maximum water table elevations. Significant discharge is generated whilst water table elevations are relatively low at gully edge locations, and this has a strong influence on flow pathways. Four characteristics of runoff response are recognised: (i) the rapid development of macropore/pipe flow at the start of the storm; (ii) peat rewetting, water table elevation increase and continued macropore/pipe flow; (iii) maximum water table elevations and peak stream discharge with throughflow occurring within the erosional acrotelm and rapid flow through the subsurface macropore/pipe network; (iv) rapidly declining water table elevations and stream flow following the cessation of rainfall. Gully edge peats provide a key linkage between the hillslope hydrological system and channel flow so that their influence on the hydrological functioning of the peatlands is disproportionate to their aerial extent within the catchment. Future climate change may lead to further degradation of the bogs and a reinforcement of the importance of erosion gullies to runoff generation and water quality.

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips - Part 1: nonuniform infiltration and soil water redistribution

NASA Astrophysics Data System (ADS)

Muñoz-Carpena, Rafael; Lauvernet, Claire; Carluer, Nadia

2018-01-01

Vegetation buffers like vegetative filter strips (VFSs) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in floodplains often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfall-runoff event. Simple and robust components of hydrological models are needed to analyze the impacts of WT in the landscape. To simulate VFS infiltration under realistic rainfall conditions with WT, we propose a generic infiltration solution (Shallow Water table INfiltration algorithm: SWINGO) based on a combination of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with new integral formulae to calculate singular times (time of ponding, shift time, and time to soil profile saturation). The algorithm was tested successfully on five distinct soils, both against Richards's numerical solution and experimental data in terms of infiltration and soil moisture redistribution predictions, and applied to study the combined effects of varying WT depth, soil type, and rainfall intensity and duration. The results show the robustness of the algorithm and its ability to handle various soil hydraulic functions and initial nonponding conditions under unsteady rainfall. The effect of a WT on infiltration under ponded conditions was found to be effectively decoupled from surface infiltration and excess runoff processes for depths larger than 1.2 to 2 m, being shallower for fine soils and shorter events. For nonponded initial conditions, the influence of WT depth also varies with rainfall intensity. Also, we observed that soils with a marked air entry (bubbling pressure) exhibit a distinct behavior with WT near the surface. The good performance, robustness, and flexibility of SWINGO supports its broader use to study WT effects on surface runoff, infiltration, flooding, transport, ecological, and land use processes. SWINGO is coupled with an existing VFS model in the companion paper (Lauvernet and Muñoz-Carpena, 2018), where the potential effects of seasonal or permanent WTs on VFS sediment and pesticide trapping are studied.

The design of a research water table

NASA Technical Reports Server (NTRS)

Fike, R. L.; Kinney, R. B.; Perkins, H. C.

1973-01-01

A complete design for a research water table is presented. Following a brief discussion of the analogy between water and compressible-gas flows (hydraulic analogy), the components of the water table and their function are described. The major design considerations are discussed, and the final design is presented.

Temporal changes in the configuration of the water table in the vicinity of the management systems evaluation area site, central Nebraska

USGS Publications Warehouse

Kilpatrick, John M.

1996-01-01

To improve understanding of the hydrologic characteristics of the shallow aquifer in the vicinity of the Management Systems Evaluation Area site near Shelton, Nebraska, water levels were measured in approximately 130 observation wells in both June and September 1991. Two water-table maps and a water-level-change map were drawn on the basis of these measurements. In addition, historical data from U.S. Geological Survey computer files and published reports were used to determine the approximate configuration of the water table in 1931 and to draw one short-term and two-long term water- level hydrographs. Comparison of the three water- table maps indicates general similarities. The average horizontal hydraulic gradient in the shallow aquifer is about 7.5 feet per mile, and the flow direction is to the east-northeast. The water table declined 2 to 10 feet between June and September 1991, with the greatest decline occurring in a wedge-shaped area south of the Wood River and north of the Platte River. The 1991 water-table configurations appear to indicate that the aquifer either was discharging to the Platte River in this reach or there was little flow between the river and the aquifer. Comparison of the 1931 and 1991 water-table maps indicates that, except for short-term variations, the water-table configuration changed little during this 61-year period. Two long-term water-level hydrographs confirm this conclusion, indicating that the shallow aquifer in this area has been in long-term, dynamic equilibrium.

Simulation of water-table aquifers using specified saturated thickness

USGS Publications Warehouse

Sheets, Rodney A.; Hill, Mary C.; Haitjema, Henk M.; Provost, Alden M.; Masterson, John P.

2014-01-01

Simulating groundwater flow in a water-table (unconfined) aquifer can be difficult because the saturated thickness available for flow depends on model-calculated hydraulic heads. It is often possible to realize substantial time savings and still obtain accurate head and flow solutions by specifying an approximate saturated thickness a priori, thus linearizing this aspect of the model. This specified-thickness approximation often relies on the use of the “confined” option in numerical models, which has led to confusion and criticism of the method. This article reviews the theoretical basis for the specified-thickness approximation, derives an error analysis for relatively ideal problems, and illustrates the utility of the approximation with a complex test problem. In the transient version of our complex test problem, the specified-thickness approximation produced maximum errors in computed drawdown of about 4% of initial aquifer saturated thickness even when maximum drawdowns were nearly 20% of initial saturated thickness. In the final steady-state version, the approximation produced maximum errors in computed drawdown of about 20% of initial aquifer saturated thickness (mean errors of about 5%) when maximum drawdowns were about 35% of initial saturated thickness. In early phases of model development, such as during initial model calibration efforts, the specified-thickness approximation can be a very effective tool to facilitate convergence. The reduced execution time and increased stability obtained through the approximation can be especially useful when many model runs are required, such as during inverse model calibration, sensitivity and uncertainty analyses, multimodel analysis, and development of optimal resource management scenarios.

A method for simulating transient ground-water recharge in deep water-table settings in central Florida by using a simple water-balance/transfer-function model

USGS Publications Warehouse

O'Reilly, Andrew M.

2004-01-01

A relatively simple method is needed that provides estimates of transient ground-water recharge in deep water-table settings that can be incorporated into other hydrologic models. Deep water-table settings are areas where the water table is below the reach of plant roots and virtually all water that is not lost to surface runoff, evaporation at land surface, or evapotranspiration in the root zone eventually becomes ground-water recharge. Areas in central Florida with a deep water table generally are high recharge areas; consequently, simulation of recharge in these areas is of particular interest to water-resource managers. Yet the complexities of meteorological variations and unsaturated flow processes make it difficult to estimate short-term recharge rates, thereby confounding calibration and predictive use of transient hydrologic models. A simple water-balance/transfer-function (WBTF) model was developed for simulating transient ground-water recharge in deep water-table settings. The WBTF model represents a one-dimensional column from the top of the vegetative canopy to the water table and consists of two components: (1) a water-balance module that simulates the water storage capacity of the vegetative canopy and root zone; and (2) a transfer-function module that simulates the traveltime of water as it percolates from the bottom of the root zone to the water table. Data requirements include two time series for the period of interest?precipitation (or precipitation minus surface runoff, if surface runoff is not negligible) and evapotranspiration?and values for five parameters that represent water storage capacity or soil-drainage characteristics. A limiting assumption of the WBTF model is that the percolation of water below the root zone is a linear process. That is, percolating water is assumed to have the same traveltime characteristics, experiencing the same delay and attenuation, as it moves through the unsaturated zone. This assumption is more accurate if the moisture content, and consequently the unsaturated hydraulic conductivity, below the root zone does not vary substantially with time. Results of the WBTF model were compared to those of the U.S. Geological Survey variably saturated flow model, VS2DT, and to field-based estimates of recharge to demonstrate the applicability of the WBTF model for a range of conditions relevant to deep water-table settings in central Florida. The WBTF model reproduced independently obtained estimates of recharge reasonably well for different soil types and water-table depths.

Water levels in observation wells in Nebraska during 1955

USGS Publications Warehouse

Keech, C.F.

1956-01-01

The objective of the dbservation-well program in Nebraska is to provide an evaluation of the status of the ground-water supplies. Many uses for water-.level data are known but not all potential uses can be forseen. Among the important uses are the following:To indicate the status of ground water in storage or in transit and the availability of supplies.To show the trend of ground-water supplies and the outlook for the future.To estimate or forcast the base flow of streams.To indicate areas in which the water level is approaching too close to the land surface (water-logging) or is receding toward economic limits of lift or tow rd impairment by water of poor quality.To provide long-term vidence for evaluating the effectiveness of land-management and water...0 nservation programs in relation to water conservation actually of ected, and for use in basin or "watershed" studies.To provide longterm ontinuous records to serve as a framework to which short-term records collected during intensive investigation may be related.The water level in an observation well functions as a gage to indicate the position of the water table o The water table is defined as the upper surface of the zone of saturation except where that surface is formed by overlying impermeable materials. The water table is also the boundary between the zone of saturation and the zone of aeration. It is not a level surface but is a sloping surface that has many irregularities, and it often conforms in a general way to the land surface. The irregularities are caused by several factors. In places where the recharge to the ground-water reservoir is exceptionally large, the water-table may rise to form a mound from which the water slowly spreads. Depressions or troughs in the water table indicate places where the ground water is discharging, as along streams that are below the normal level of the water table, or indicate places where water is being withdrawn by wells or vegetation.The several factors that influence the water table vary in fact and amount from time to time because of changes in weather and the water requirements of vegetation and man; thus, the water table is nearly always rising or falling.The fluctuations of the water table are shown by the changes in water levels in wells. Thus, the rate and amount of the fluctuation of the water table can be ascertained by observing the water levels in wells, and the magnitude of the several factors effecting the position of the water table can be interpreted by analyzing the water—level data.Water-level measurements are given, in this report, in feet below the land surface at the well site. Water levels that are above land surface are preceded by a plus (+) sign, whereas those below land surface have no sign but are understood to be minus (-). The words "land-surface datum" are abbreviated "lsd" in tables of this report.The altitude above mean sea level (msl) of the land surface at many of the well sites has been determined and is included in the tables of this report.Lower case letters which appear in the table of water level measurements indicate the following: 6', nearby well pumped recently; f, dry; g, measured by outside agency; and j, frozen.Twenty-.six observation wells in Nebraska are equipped with recording gages. Each recording gage produces a continuous graph of water-level fluctuations in the well. Only the lowest water level on the last day of record in each month, as recorded by the gage, is given in this report; the complete record is on file in the office of the U. S. Geological Survey in Lincoln, Nebr.

Discoloration of polyvinyl chloride (PVC) tape as a proxy for water-table depth in peatlands: validation and assessment of seasonal variability

USGS Publications Warehouse

Booth, Robert K.; Hotchkiss, Sara C.; Wilcox, Douglas A.

2005-01-01

Summary: 1. Discoloration of polyvinyl chloride (PVC) tape has been used in peatland ecological and hydrological studies as an inexpensive way to monitor changes in water-table depth and reducing conditions. 2. We investigated the relationship between depth of PVC tape discoloration and measured water-table depth at monthly time steps during the growing season within nine kettle peatlands of northern Wisconsin. Our specific objectives were to: (1) determine if PVC discoloration is an accurate method of inferring water-table depth in Sphagnum-dominated kettle peatlands of the region; (2) assess seasonal variability in the accuracy of the method; and (3) determine if systematic differences in accuracy occurred among microhabitats, PVC tape colour and peatlands. 3. Our results indicated that PVC tape discoloration can be used to describe gradients of water-table depth in kettle peatlands. However, accuracy differed among the peatlands studied, and was systematically biased in early spring and late summer/autumn. Regardless of the month when the tape was installed, the highest elevations of PVC tape discoloration showed the strongest correlation with midsummer (around July) water-table depth and average water-table depth during the growing season. 4. The PVC tape discoloration method should be used cautiously when precise estimates are needed of seasonal changes in the water-table.

40 CFR Table 6 to Subpart Kkkkk of... - Continuous Compliance With Emission Limitations and Work Practice Standards

Code of Federal Regulations, 2010 CFR

2010-07-01

... or DLS/FF i. If you use a bag leak detection system, initiating corrective action within 1 hour of a bag leak detection system alarm and completing corrective actions in accordance with your OM&M plan... established during the performance test; and iv. If chemicals are added to the scrubber water, collecting the...

Global patterns of groundwater table depth.

PubMed

Fan, Y; Li, H; Miguez-Macho, G

2013-02-22

Shallow groundwater affects terrestrial ecosystems by sustaining river base-flow and root-zone soil water in the absence of rain, but little is known about the global patterns of water table depth and where it provides vital support for land ecosystems. We present global observations of water table depth compiled from government archives and literature, and fill in data gaps and infer patterns and processes using a groundwater model forced by modern climate, terrain, and sea level. Patterns in water table depth explain patterns in wetlands at the global scale and vegetation gradients at regional and local scales. Overall, shallow groundwater influences 22 to 32% of global land area, including ~15% as groundwater-fed surface water features and 7 to 17% with the water table or its capillary fringe within plant rooting depths.

Influence of water table on carbon dioxide, carbon monoxide, and methane fluxes from taiga bog microcosms

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

Funk, D.W.; Pullmann, E.R.; Peterson, K.M.

1994-09-01

Hydrological changes, particularly alterations in water table level, may largely overshadow the more direct effects of global temperature increase upon carbon cycling in arctic and subarctic wetlands. Frozen cores (n=40) of intact soils and vegetation were collected from a bog near Fairbanks, Alaska, and fluxes of CO{sub 2}, CH{sub 4}, and Co in response to water table variation were studied under controlled conditions in the Duke University phytotron. Core microcosms thawed to a 20-cm depth over 30 days under a 20 hour photoperiod with a day/night temperature regime of 20/10{degrees}C. After 30 days the water table in 20 microcosms wasmore » decreased from the soil surface to -15 cm and maintained at the soil surface in 20 control cores. Outward fluxes of CO{sub 2} (9-16 g m{sup -2}d{sup -1}) and CO (3-4 mg m{sup -2}d{sup -1}) were greatest during early thaw and decreased to near zero for both gases before the water table treatment started. Lower water table tripled CO{sub 2} flux to the atmosphere when compared with control cores. Carbon monoxide was emitted at low rates from high water table cores and consumed by low water table cores. Methane fluxes were low (<1 mg m{sup -2}d{sup -1}) in all cores during thaw. High water table cores increased CH{sub 4} flux to 8-9 mg m{sup -2}d{sup -1} over 70 days and remained high relative to the low water table cores (<0.74 mg m{sup -2}d{sup -1}). Although drying of wetland taiga soils may decrease CH{sub 4} emissions to the atmosphere, the associated increase in CO{sub 2} due to aerobic respiration will likely increase the global warming potential of gas emissions from these soils. 43 refs., 4 figs.« less

40 CFR Table 3 to Subpart Cccc of... - Initial Compliance With Emission Limitations

Code of Federal Regulations, 2014 CFR

2014-07-01

... Yeast Pt. 63, Subpart CCCC, Table 3 Table 3 to Subpart CCCC of Part 63—Initial Compliance With Emission... demonstrated initial compliance if . . . 1. Each fed-batch fermenter producing yeast in a fermentation stage... yeast in a fermentation stage (last (Trade), second-to-last (First Generation), or third-to-last (Stock...

40 CFR Table 3 to Subpart Cccc of... - Initial Compliance With Emission Limitations

Code of Federal Regulations, 2012 CFR

2012-07-01

... Yeast Pt. 63, Subpart CCCC, Table 3 Table 3 to Subpart CCCC of Part 63—Initial Compliance With Emission... demonstrated initial compliance if . . . 1. Each fed-batch fermenter producing yeast in a fermentation stage... yeast in a fermentation stage (last (Trade), second-to-last (First Generation), or third-to-last (Stock...

40 CFR Table 3 to Subpart Cccc of... - Initial Compliance With Emission Limitations

Code of Federal Regulations, 2013 CFR

2013-07-01

... Yeast Pt. 63, Subpart CCCC, Table 3 Table 3 to Subpart CCCC of Part 63—Initial Compliance With Emission... demonstrated initial compliance if . . . 1. Each fed-batch fermenter producing yeast in a fermentation stage... yeast in a fermentation stage (last (Trade), second-to-last (First Generation), or third-to-last (Stock...

Response of plant community structure and primary productivity to experimental drought and flooding in an Alaskan fen

USGS Publications Warehouse

Churchill, A.C.; Turetsky, Merritt R.; McGuire, A. David; Hollingsworth, Teresa N.

2014-01-01

Northern peatlands represent a long-term net sink for atmospheric CO2, but these ecosystems can shift from net carbon (C) sinks to sources based on changing climate and environmental conditions. In particular, changes in water availability associated with climate control peatland vegetation and carbon uptake processes. We examined the influence of changing hydrology on plant species abundance and ecosystem primary production in an Alaskan fen by manipulating the water table in field treatments to mimic either sustained flooding (raised water table) or drought (lowered water table) conditions for 6 years. We found that water table treatments altered plant species abundance by increasing sedge and grass cover in the raised water table treatment and reducing moss cover while increasing vascular green area in the lowered water table treatment. Gross primary productivity was lower in the lowered treatment than in the other plots, although there were no differences in total biomass or vascular net primary productivity among the treatments. Overall, our results indicate that vegetation abundance was more sensitive to variation in water table than total biomass and vascular biomass accrual. Finally, in our experimental peatland, drought had stronger consequences for change in vegetation abundance and ecosystem function than sustained flooding.

Hydrogeology of the surficial aquifer in the vicinity of a former landfill, Naval Submarine Base Kings Bay, Camden County, Georgia

USGS Publications Warehouse

Leeth, David C.

1999-01-01

Neogene and Quaternary sediments constitute the surficial aquifer beneath the study area; in descending order from youngest to oldest these include-the Quaternary undifferentiated surficial sand and Satilla Formation; the Pliocene(?) Cypresshead Formation; and the middle Miocene Coosawhatchie Formation. Beneath the surficial aquifer, the upper Brunswick aquifer consists of part of the lower Miocene Marks Head Formation. The surficial aquifer is divided into three water-bearing zones on the basis of lithologic and geophysical properties of sediments, hydraulic-head differences between zones, and differences in ground-water chemistry. The shallowest zone-the water-table zone-consists of medium to fine sand and clayey sand and is present from land surface to a depth of about 77 feet. Below the water-table zone, the confined upper water-bearing zone consists of medium to very coarse sand and is present from a depth of about 110 to 132 feet. Beneath the upper water-bearing zone, the confined lower water-bearing zone consists of coarse sand and very fine gravel and is present from a depth of about 195 to 237 feet. Hydraulic separation is suggested by differences in water chemistry between the water-table zone and upper water-bearing zone. The sodium chloride type water in the water-table zone differs from the calcium bicarbonate type water in the upper water-bearing zone. Hydraulic separation also is indicated by hydraulic head differences of more than 6.5 feet between the water-table zone and the upper water-bearing zone. Continuous and synoptic water-level measurements in the water-table zone, from October 1995 to April 1997, indicate the presence of a water-table high beneath and adjacent to the former landfill-the surface of which varies about 5 feet with time because of recharge and discharge. Water-level data from clustered wells also suggest that restriction of vertical ground-water flow begins to occur at an altitude of about 5 to 10 feet below sea level (35 to 40 feet below land surface) in the water-table zone because of the increasing clay content of the Cypresshead Formation.

40 CFR Table 42 to Subpart Uuu of... - Additional Information for Initial Notification of Compliance Status

Code of Federal Regulations, 2010 CFR

2010-07-01

... Notification of Compliance Status 42 Table 42 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL... Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 42 Table 42 to Subpart UUU of Part 63—Additional Information for Initial Notification of...

40 CFR Table 42 to Subpart Uuu of... - Additional Information for Initial Notification of Compliance Status

Code of Federal Regulations, 2011 CFR

2011-07-01

... Notification of Compliance Status 42 Table 42 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL... Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 42 Table 42 to Subpart UUU of Part 63—Additional Information for Initial Notification of...

Soil-water content characterisation in a modified Jarvis-Stewart model: A case study of a conifer forest on a shallow unconfined aquifer

NASA Astrophysics Data System (ADS)

Guyot, Adrien; Fan, Junliang; Oestergaard, Kasper T.; Whitley, Rhys; Gibbes, Badin; Arsac, Margaux; Lockington, David A.

2017-01-01

Groundwater-vegetation-atmosphere fluxes were monitored for a subtropical coastal conifer forest in South-East Queensland, Australia. Observations were used to quantify seasonal changes in transpiration rates with respect to temporal fluctuations of the local water table depth. The applicability of a Modified Jarvis-Stewart transpiration model (MJS), which requires soil-water content data, was assessed for this system. The influence of single depth values compared to use of vertically averaged soil-water content data on MJS-modelled transpiration was assessed over both a wet and a dry season, where the water table depth varied from the surface to a depth of 1.4 m below the surface. Data for tree transpiration rates relative to water table depth showed that trees transpire when the water table was above a threshold depth of 0.8 m below the ground surface (water availability is non-limiting). When the water table reached the ground surface (i.e., surface flooding) transpiration was found to be limited. When the water table is below this threshold depth, a linear relationship between water table depth and the transpiration rate was observed. MJS modelling results show that the influence of different choices for soil-water content on transpiration predictions was insignificant in the wet season. However, during the dry season, inclusion of deeper soil-water content data improved the model performance (except for days after isolated rainfall events, here a shallower soil-water representation was better). This study demonstrated that, to improve MJS simulation results, appropriate selection of soil water measurement depths based on the dynamic behaviour of soil water profiles through the root zone was required in a shallow unconfined aquifer system.

Assessing Adaptation with Asymmetric Climate Information: evidence from water bargaining field experiments in Northeast Brazil

NASA Astrophysics Data System (ADS)

Pfaff, A.; Velez, M.; Taddei, R.; Broad, K.

2011-12-01

We assess how asymmetric climate information affects bargaining -- an adaptation institution. As often observed in the field, some actors lack information. This yields vulnerability, despite participation. We examine the loss for a participant from being uncertain about water quantity when bargaining with a fully informed participant in an ultimatum game in Northeast Brazil. When all are fully informed, our field populations in the capital city and an agricultural valley produce a typical 60-40 split between those initiating and responding in one-shot bargaining. With asymmetric information, when initiators know the water quantity is low they get 80%. Thus even within bargaining, i.e. given strong participation, better integrating climate science into water management via greater effort to communicate relevant information to all involved can help to avoid inequities that could arise despite all of the stakeholders being 'at the table', as may well occur within future water allocation along a large new canal in the case we study.

Estimated depth to the water table and estimated rate of recharge in outcrops of the Chicot and Evangeline aquifers near Houston, Texas

USGS Publications Warehouse

Noble, J.E.; Bush, P.W.; Kasmarek, M.C.; Barbie, D.L.

1996-01-01

In 1989, the U.S. Geological Survey, in cooperation with the Harris-Galveston Coastal Subsidence District, began a field study to determine the depth to the water table and to estimate the rate of recharge in outcrops of the Chicot and Evangeline aquifers near Houston, Texas. The study area comprises about 2,000 square miles of outcrops of the Chicot and Evangeline aquifers in northwest Harris County, Montgomery County, and southern Walker County. Because of the scarcity of measurable water-table wells, depth to the water table below land surface was estimated using a surface geophysical technique, seismic refraction. The water table in the study area generally ranges from about 10 to 30 foot below land surface and typically is deeper in areas of relatively high land-surface altitude than in areas of relatively low land- surface altitude. The water table has demonstrated no long-term trends since ground-water development began, with the probable exception of the water table in the Katy area: There the water table is more than 75 feet deep, probably due to ground-water pumpage from deeper zones. An estimated rate of recharge in the aquifer outcrops was computed using the interface method in which environmental tritium is a ground-water tracer. The estimated average total recharge rate in the study area is 6 inches per year. This rate is an upper bound on the average recharge rate during the 37 years 1953-90 because it is based on the deepest penetration (about 80 feet) of postnuclear-testing tritium concentrations. The rate, which represents one of several components of a complex regional hydrologic budget, is considered reasonable but is not definitive because of uncertainty regarding the assumptions and parameters used in its computation.

Links between climate change, water-table depth, and water chemistry in a mineralized mountain watershed

USGS Publications Warehouse

Manning, Andrew H.; Verplanck, Philip L.; Caine, Jonathan S.; Todd, Andrew S.

2013-01-01

Recent studies suggest that climate change is causing rising solute concentrations in mountain lakes and streams. These changes may be more pronounced in mineralized watersheds due to the sensitivity of sulfide weathering to changes in subsurface oxygen transport. Specific causal mechanisms linking climate change and accelerated weathering rates have been proposed, but in general remain entirely hypothetical. For mineralized watersheds, a favored hypothesis is that falling water tables caused by declining recharge rates allow an increasing volume of sulfide-bearing rock to become exposed to air, thus oxygen. Here, we test the hypothesis that falling water tables are the primary cause of an increase in metals and SO4 (100-400%) observed since 1980 in the Upper Snake River (USR), Colorado. The USR drains an alpine watershed geologically and climatologically representative of many others in mineralized areas of the western U.S. Hydrologic and chemical data collected from 2005 to 2011 in a deep monitoring well (WP1) at the top of the USR watershed are utilized. During this period, both water table depths and groundwater SO4 concentrations have generally increased in the well. A numerical model was constructed using TOUGHREACT that simulates pyrite oxidation near WP1, including groundwater flow and oxygen transport in both saturated and unsaturated zones. The modeling suggests that a falling water table could produce an increase in metals and SO4 of a magnitude similar to that observed in the USR (up to 300%). Future water table declines may produce limited increases in sulfide weathering high in the watershed because of the water table dropping below the depth of oxygen penetration, but may continue to enhance sulfide weathering lower in the watershed where water tables are shallower. Advective air (oxygen) transport in the unsaturated zone caused by seasonally variable recharge and associated water table fluctuations was found to have little influence on pyrite oxidation rates near WP1. However, this mechanism could be important in the case of a shallow dynamic water table and more abundant/reactive sulfides in the shallow subsurface. Data from WP1 and numerical modeling results are thus consistent with the falling water table hypothesis, and illustrate fundamental processes linking climate and sulfide weathering in mineralized watersheds.

WTAQ: A Computer Program for Calculating Drawdowns and Estimating Hydraulic Properties for Confined and Water-Table Aquifers

USGS Publications Warehouse

Barlow, Paul M.; Moench, Allen F.

1999-01-01

The computer program WTAQ calculates hydraulic-head drawdowns in a confined or water-table aquifer that result from pumping at a well of finite or infinitesimal diameter. The program is based on an analytical model of axial-symmetric ground-water flow in a homogeneous and anisotropic aquifer. The program allows for well-bore storage and well-bore skin at the pumped well and for delayed drawdown response at an observation well; by including these factors, it is possible to accurately evaluate the specific storage of a water-table aquifer from early-time drawdown data in observation wells and piezometers. For water-table aquifers, the program allows for either delayed or instantaneous drainage from the unsaturated zone. WTAQ calculates dimensionless or dimensional theoretical drawdowns that can be used with measured drawdowns at observation points to estimate the hydraulic properties of confined and water-table aquifers. Three sample problems illustrate use of WTAQ for estimating horizontal and vertical hydraulic conductivity, specific storage, and specific yield of a water-table aquifer by type-curve methods and by an automatic parameter-estimation method.

Simulating the Effects of Drainage and Agriculture on Hydrology and Sediment in the Minnesota River Basin

NASA Astrophysics Data System (ADS)

Downer, C. W.; Pradhan, N. R.; Skahill, B. E.; Banitt, A. M.; Eggers, G.; Pickett, R. E.

2014-12-01

Throughout the Midwest region of the United States, slopes are relatively flat, soils tend to have low permeability, and local water tables are high. In order to make the region suitable for agriculture, farmers have installed extensive networks of ditches to drain off excess surface water and subsurface tiles to lower the water table and remove excess soil water in the root zone that can stress common row crops, such as corn and soybeans. The combination of tiles, ditches, and intensive agricultural land practices radically alters the landscape and hydrology. Within the watershed, tiles have outlets to both the ditch/stream network as well as overland locations, where the tile discharge appears to initiate gullies and exacerbate overland erosion. As part of the Minnesota River Basin Integrated Study we are explicitly simulating the tile and drainage systems in the watershed at multiple scales using the physics-based watershed model GSSHA (Gridded Surface Subsurface Hydrologic Analysis). The tile drainage system is simulated as a network of pipes that collect water from the local water table. Within the watershed, testing of the methods on smaller basins shows the ability of the model to simulate tile flow, however, application at the larger scale is hampered by the computational burden of simulating the flow in the complex tile drain networks that drain the agricultural fields. Modeling indicates the subsurface drains account for approximately 40% of the stream flow in the Seven Mile Creek sub-basin account in the late spring and early summer when the tile is flowing. Preliminary results indicate that agricultural tile drains increase overland erosion in the Seven Mile Creek watershed.

Understanding the Impact of Ground Water Treatment and Evapotranspiration Parameterizations in the NCEP Climate Forecast System (CFS) on Warm Season Predictions

NASA Astrophysics Data System (ADS)

Ek, M. B.; Yang, R.

2016-12-01

Skillful short-term weather forecasts, which rely heavily on quality atmospheric initial conditions, have a fundamental limit of about two weeks owing to the chaotic nature of the atmosphere. Useful forecasts at sub-seasonal to seasonal time scales, on the other hand, require well-simulated large-scale atmospheric response to slowly varying lower boundary forcings from both the ocean and land surface. The critical importance of ocean has been recognized, where the ocean indices have been used in a variety of climate applications. In contrast, the impact of land surface anomalies, especially soil moisture and associated evaporation, has been proven notably difficult to demonstrate. The Noah Land Surface Model (LSM) is the land component of NCEP CFS version 2 (CFSv2) used for seasonal predictions. The Noah LSM originates from the Oregon State University (OSU) LSM. The evaporation control in the Noah LSM is based on the Penman-Monteith equation, which takes into account the solar radiation, relative humidity, air temperature, and soil moisture effects. The Noah LSM is configured with four soil layers with a fixed depth of 2 meters and free drainage at the bottom soil layer. This treatment assumes that the soil water table depth is well within the specified range, and also potentially misrepresents the soil moisture memory effects at seasonal time scales. To overcome the limitation, an unconfined aquifer is attached to the bottom of the soil to allow the water table to move freely up and down. In addition, in conjunction with the water table, an alternative Ball-Berry photosynthesis-based evaporation parameterization is examined to evaluate the impact from using a different evaporation control methodology. Focusing on the 2011 and 2012 intense summer droughts in the central US, seasonal ensemble forecast experiments with early May initial conditions are carried out for the two years using an enhanced version of CFSv2, where the atmospheric component of the CFSv2 is coupled to the Noah Multiple-Parameterization (Noah-MP) land model. The Noah-MP has different options for ground water and evaporation control parameterizations. The differences will be presented and results will be discussed.

Ground-water quality beneath solid-waste disposal sites at anchorage, Alaska

USGS Publications Warehouse

Zenone, Chester; Donaldson, D.E.; Grunwaldt, J.J.

1975-01-01

Studies at three solid-waste disposal sites in the Anchorage area suggest that differences in local geohydrologic conditions influence ground-water quality. A leachate was detected in ground water within and beneath two sites where the water table is very near land surface and refuse is deposited either at or below the water table in some parts of the filled areas. No leachate was detected in ground water beneath a third site where waste disposal is well above the local water table.

Real-time 4D ERT monitoring of river water intrusion into a former nuclear disposal site using a transient warping-mesh water table boundary (Invited)

NASA Astrophysics Data System (ADS)

Johnson, T.; Hammond, G. E.; Versteeg, R. J.; Zachara, J. M.

2013-12-01

The Hanford 300 Area, located adjacent to the Columbia River in south-central Washington, USA, is the site of former research and uranium fuel rod fabrication facilities. Waste disposal practices at site included discharging between 33 and 59 metric tons of uranium over a 40 year period into shallow infiltration galleries, resulting in persistent uranium contamination within the vadose and saturated zones. Uranium transport from the vadose zone to the saturated zone is intimately linked with water table fluctuations and river water intrusion driven by upstream dam operations. As river stage increases, the water table rises into the vadose zone and mobilizes contaminated pore water. At the same time, river water moves inland into the aquifer, and river water chemistry facilitates further mobilization by enabling uranium desorption from contaminated sediments. As river stage decreases, flow moves toward the river, ultimately discharging contaminated water at the river bed. River water specific conductance at the 300 Area varies around 0.018 S/m whereas groundwater specific conductance varies around 0.043 S/m. This contrast provides the opportunity to monitor groundwater/river water interaction by imaging changes in bulk conductivity within the saturated zone using time-lapse electrical resistivity tomography. Previous efforts have demonstrated this capability, but have also shown that disconnecting regularization constraints at the water table is critical for obtaining meaningful time-lapse images. Because the water table moves with time, the regularization constraints must also be transient to accommodate the water table boundary. This was previously accomplished with 2D time-lapse ERT imaging by using a finely discretized computational mesh within the water table interval, enabling a relatively smooth water table to be defined without modifying the mesh. However, in 3D this approach requires a computational mesh with an untenable number of elements. In order to accommodate the water table boundary in 3D, we propose a time-lapse warping mesh inversion, whereby mesh elements that traverse the water table are modified to generate a smooth boundary at the known water table position, enabling regularization constraints to be accurately disconnected across the water table boundary at a given time. We demonstrate the approach using a surface ERT array installed adjacent to the Columbia River at the 300 Area, consisting of 352 electrodes and covering an area of approximately 350 m x 350 m. Using autonomous data collection, transmission, and filtering tools coupled with high performance computing resources, the 4D imaging process is automated and executed in real time. Each time lapse survey consists of approximately 40,000 measurements and 4 surveys are collected and processed per day from April 1st , 2013 to September 30th, 2013. The data are inverted on an unstructured tetrahedral mesh that honors LiDAR-based surface topography and is comprised of approximately 905,000 elements. Imaging results show the dynamic 4D extent of river water intrusion, and are validated with well-based fluid conductivity measurements at each monitoring well within the imaging domain.

Environmental Regulatory Update Table, January/February 1995

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

Houlberg, L.M.; Hawkins, G.T.; Bock, R.E.

1995-03-01

The Environmental Regulatory Update Table provides information on regulatory initiatives impacting environmental, health, and safety management responsibilities. the table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

50 CFR Table 32 to Part 679 - Amendment 80 Initial QS Pool

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Amendment 80 Initial QS Pool 32 Table 32 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679, Table 32 Table 32 to Part 679—...

40 CFR Table 7 to Subpart Eeee of... - Initial Compliance With Work Practice Standards

Code of Federal Regulations, 2014 CFR

2014-07-01

... equivalent control that meets the requirements in Table 4 to this subpart, item 1.a i. After emptying and... out a leak detection and repair program or equivalent control according to one of the subparts listed... (Non-Gasoline) Pt. 63, Subpt. EEEE, Table 7 Table 7 to Subpart EEEE of Part 63—Initial Compliance With...

40 CFR Table 7 to Subpart Eeee of... - Initial Compliance With Work Practice Standards

Code of Federal Regulations, 2012 CFR

2012-07-01

... equivalent control that meets the requirements in Table 4 to this subpart, item 1.a i. After emptying and... out a leak detection and repair program or equivalent control according to one of the subparts listed... (Non-Gasoline) Pt. 63, Subpt. EEEE, Table 7 Table 7 to Subpart EEEE of Part 63—Initial Compliance With...

40 CFR Table 7 to Subpart Eeee of... - Initial Compliance With Work Practice Standards

Code of Federal Regulations, 2013 CFR

2013-07-01

... equivalent control that meets the requirements in Table 4 to this subpart, item 1.a i. After emptying and... out a leak detection and repair program or equivalent control according to one of the subparts listed... (Non-Gasoline) Pt. 63, Subpt. EEEE, Table 7 Table 7 to Subpart EEEE of Part 63—Initial Compliance With...

40 CFR Table 42 to Subpart Uuu of... - Additional Information for Initial Notification of Compliance Status

Code of Federal Regulations, 2013 CFR

2013-07-01

... Notification of Compliance Status 42 Table 42 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL..., Subpt. UUU, Table 42 Table 42 to Subpart UUU of Part 63—Additional Information for Initial Notification... source or vent associated with an affected source not subject to the requirements of subpart UUU. 2...

40 CFR Table 42 to Subpart Uuu of... - Additional Information for Initial Notification of Compliance Status

Code of Federal Regulations, 2012 CFR

2012-07-01

... Notification of Compliance Status 42 Table 42 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL..., Subpt. UUU, Table 42 Table 42 to Subpart UUU of Part 63—Additional Information for Initial Notification... source or vent associated with an affected source not subject to the requirements of subpart UUU. 2...

40 CFR Table 42 to Subpart Uuu of... - Additional Information for Initial Notification of Compliance Status

Code of Federal Regulations, 2014 CFR

2014-07-01

... Notification of Compliance Status 42 Table 42 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL..., Subpt. UUU, Table 42 Table 42 to Subpart UUU of Part 63—Additional Information for Initial Notification... source or vent associated with an affected source not subject to the requirements of subpart UUU. 2...

Altitude of the water table in the alluvial and other shallow aquifers along the Colorado River near La Grange, Texas, December 1980

USGS Publications Warehouse

Rettman, Paul

1981-01-01

The delineation of the water table in the alluvium of the Colorado River is fairly well defined, and 10-feet contour intervals may be interpreted with confidence in the area called ' potential lignite-mining area. ' The water table in the bedrock aquifers is more difficult to delineate with the available data; therefore, the contours are only estimates of the position of the water table in the hilly bedrock area adjacent to the Colorado River alluvium. 

Hydrologic conditions, recharge, and baseline water quality of the surficial aquifer system at Jekyll Island, Georgia, 2012-13

USGS Publications Warehouse

Gordon, Debbie W.; Torak, Lynn J.

2016-03-08

Groundwater levels and specific-conductance measurements showed the dependence of freshwater resources on rainfall to recharge the water-table zone of the surficial aquifer system and to influence groundwater flow on Jekyll Island. The unseasonably dry conditions during November 2012 to April 2013 induced saline water infiltration to the water-table zone from the marshland separating the Jekyll River from the island. A strong correlation (R2 = 0.97) of specific conductance to chloride concentration in water samples from wells installed in the water-table zone provided support for the determination of seasonal directions of groundwater flow by confirming salinity changes in the water-table zone. Unseasonably wet conditions during the late spring to August caused groundwater-flow reversals in some areas. The high dependence of the water-table zone in the surficial aquifer system on precipitation to replenish the aquifer with freshwater underscored the importance of monitoring groundwater levels, water quality, and water use to identify aquifer-discharge conditions that have the potential to promote seawater encroachment and degrade freshwater resources on Jekyll Island.

Evapotranspiration, Water Table Fluctuations, and Riparian Restoration: Report Documentary 2007-2008 Work

DTIC Science & Technology

2010-09-01

is delineated in upper third in 2006 image. .............................................................................. 23 Figure 19. NDVI ...values are compared for SPOT imagery from 29 May 2006 and 24 August 2006. Fire areas with reduced NDVI from Malpais fire are clearly seen on both sides...results comparing vegetation type and normalized difference vegetation index ( NDVI ), and (4) presents initial results from the groundwater flow field

The impact of conjunctive use of canal and tube well water in Lagar irrigated area, Pakistan

NASA Astrophysics Data System (ADS)

Kazmi, Syed Iftikhar; Ertsen, Maurits W.; Asi, Muhammad Rafique

Introduction of the large gravity irrigation system in the Indus Basin in the late 19th century without a drainage system resulted in a rising water table, which resulted in water logging and salinity problems over large areas. In order to cope with the salinity and water logging problem, the Pakistan government initiated installation of 10,000 tube wells in different areas. This not only resulted in the lowering of water table, but also supplemented irrigation. Resulting benefits from the irrigation opportunities motivated framers to install private tube wells. The Punjab area meets 40% of its irrigation needs from groundwater abstraction. Today, farmers apply both surface water flows and groundwater from tube wells, creating a pattern of private and public water control. Sustainable use of groundwater needs proper quantification of the resource and information on processes involved in its recharge and discharge. The field work in the Lagar irrigated area, discussed in this paper, show that within the general picture of conjunctive use of canal water and groundwater, there is a clear spatial pattern between upstream and downstream areas, with upstream areas depending much less on groundwater than downstream areas. The irrigation context in the study area proves to be highly complex, with water users having differential access to canal and tube well water, resulting in different responses of farmers with their irrigation strategies, which in turn affect the salinity and water balances on the fields.

Hydrology and chemistry of groundwater and seasonal ponds in the Atlantic Coastal Plain in Delaware, USA

USGS Publications Warehouse

Phillips, P.J.; Shedlock, R.J.

1993-01-01

The hydrochemistry of small seasonal ponds was investigated by studying relations between ground-water and surface water in a forested Coastal Plain drainage basin. Observation of changes in the water table in a series of wells equipped with automatic water-level recorders showed that the relation between water-table configuration and basin topography changes seasonally, and particularly in response to spring recharge. Furthermore, in this study area the water table is not a subdued expression of the land surface topography, as is commonly assumed. During the summer and fall months, a water-table trough underlies sandy ridges separating the seasonal ponds, and maximum water-table altitudes prevail in the sediments beneath the dry pond bottoms. As the ponds fill with water during the winter, maximum water-table altitudes shift to the upland-margin zone adjacent to the seasonal ponds. Increases in pond stage are associated with the development of transient water-table mounds at the upland-margin wells during the spring. The importance of small local-flow systems adjacent to the seasonal ponds also is shown by the similarities in the chemistry of the shallow groundwater in the upland margin and water in the seasonal ponds. The upland margin and surface water samples have low pH (generally less than 5.0), and contain large concentrations of dissolved aluminum (generally more than 100 ??g 1-1), and low bicarbonate concentrations (2 mg l4 or less). In contrast, the parts of the surficial aquifer that do not experience transient mounding have higher pH and larger concentrations of bicarbonate. These results suggest that an understanding of the hydrochemistry of seasonally ponded wetlands requires intensive study of the adjacent shallow groundwater-flow system. ?? 1993.

The complex relationships between methane emissions and water table at an ombrotrophic bog

NASA Astrophysics Data System (ADS)

Humphreys, Elyn; Roulet, Nigel; Moore, Tim

2017-04-01

Broad spatial and temporal variations in methane emissions from peatlands have been related to many variables including water table position, temperature and vegetation characteristics and functioning. In general, wetter peatlands tend to have greater methane emissions. However, over shorter periods of time and space, the relationship between water table and methane emissions can reverse, show hysteresis or be absent entirely. These relationships are investigated at the Mer Bleue Bog, a temperate ombrotrophic bog near Ottawa, Canada. Six years of concurrent growing season eddy covariance and automated chamber fluxes reveal the expected broad patterns. During the wettest growing season, the water table remained within 40 cm of the bog's hummock surfaces. Methane emissions were upwards of 20 to 45 mg C m-2 d-1 and exceeded the emission rates from two drier growing seasons which saw periods where the water table dropped to nearly 80 cm below the hummock surface. In those periods, methane emission rates declined to about 5 mg C m-2 d-1 or less. Lawn plots with aerenchymatous Eriophorum vegetation and high water tables had greatest emissions (exceeding 200 mg C m-2 d-1) compared to hummock plots vegetated by ericaceous shrubs, which had emissions rates similar to those measured by eddy covariance. However, within a growing season, hysteresis and inverse relationships between water table and methane emissions were observed at both ecosystem and chamber plot scales. These included periods between rainfall events where methane emissions increased while the water table deepened. The potential roles of methane production, consumption, storage and transport processes on these patterns will be discussed.

Environmental Regulatory Update Table, October 1991

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1991-11-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated each month with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, December 1991

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1992-01-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated each month with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, January--February 1993

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1993-03-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental regulatory update table, March--April 1994

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

Houlberg, L.M.; Hawkins, G.T.; Bock, R.E.

1994-03-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental regulatory update table, September--October 1992

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

Houlberg, L.M.; Hawkins, G.T.; Lewis, E.B.

1992-11-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, September/October 1993

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1993-11-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operation and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, January--February 1994

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1994-03-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations ad contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental regulatory update table November--December 1994

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

Houlberg, L.M.; Hawkins, G.T.; Bock, R.E.

1995-01-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, November--December 1992

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

Houlberg, L.M.; Hawkins, G.T.; Lewis, E.B.

1993-01-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly wit information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, July--August 1992

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

Houlberg, L.M.; Hawkins, G.T.; Lewis, E.B.

1992-09-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, September 1991

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1991-10-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated each month with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table July/August 1993

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1993-09-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, August 1991

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

Houlberg, L.M., Hawkins, G.T.; Salk, M.S.

1991-09-01

This Environmental Regulatory Update Table (August 1991) provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated each month with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, November 1991

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1991-12-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated each month with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, March/April 1993

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1993-05-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bimonthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental regulatory update table, July/August 1994

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

Houlberg, L.M.; Hawkins, G.T.; Bock, R.E.

1994-09-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, March/April 1993. Revision 1

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1993-05-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bimonthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, May/June 1993

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1993-07-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bimonthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Environmental Regulatory Update Table, May--June 1994

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

Houlberg, L.M.; Hawkins, G.T.; Bock, R.E.

1994-07-01

The Environmental Regulatory Update Table provides information on regulatory initiatives of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bimonthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

Ice Cloud Properties in Ice-Over-Water Cloud Systems Using TRMM VIRS and TMI Data

NASA Technical Reports Server (NTRS)

Minnis, Patrick; Huang, Jianping; Lin, Bing; Yi, Yuhong; Arduini, Robert F.; Fan, Tai-Fang; Ayers, J. Kirk; Mace, Gerald G.

2007-01-01

A multi-layered cloud retrieval system (MCRS) is updated and used to estimate ice water path in maritime ice-over-water clouds using Visible and Infrared Scanner (VIRS) and TRMM Microwave Imager (TMI) measurements from the Tropical Rainfall Measuring Mission spacecraft between January and August 1998. Lookup tables of top-of-atmosphere 0.65- m reflectance are developed for ice-over-water cloud systems using radiative transfer calculations with various combinations of ice-over-water cloud layers. The liquid and ice water paths, LWP and IWP, respectively, are determined with the MCRS using these lookup tables with a combination of microwave (MW), visible (VIS), and infrared (IR) data. LWP, determined directly from the TMI MW data, is used to define the lower-level cloud properties to select the proper lookup table. The properties of the upper-level ice clouds, such as optical depth and effective size, are then derived using the Visible Infrared Solar-infrared Split-window Technique (VISST), which matches the VIRS IR, 3.9- m, and VIS data to the multilayer-cloud lookup table reflectances and a set of emittance parameterizations. Initial comparisons with surface-based radar retrievals suggest that this enhanced MCRS can significantly improve the accuracy and decrease the IWP in overlapped clouds by 42% and 13% compared to using the single-layer VISST and an earlier simplified MW-VIS-IR (MVI) differencing method, respectively, for ice-over-water cloud systems. The tropical distribution of ice-over-water clouds is the same as derived earlier from combined TMI and VIRS data, but the new values of IWP and optical depth are slightly larger than the older MVI values, and exceed those of single-layered layered clouds by 7% and 11%, respectively. The mean IWP from the MCRS is 8-14% greater than that retrieved from radar retrievals of overlapped clouds over two surface sites and the standard deviations of the differences are similar to those for single-layered clouds. Examples of a method for applying the MCRS over land without microwave data yield similar differences with the surface retrievals. By combining the MCRS with other techniques that focus primarily on optically thin cirrus over low water clouds, it will be possible to more fully assess the IWP in all conditions over ocean except for precipitating systems.

Groundwater in the Boreal Plains: How Climate and Geology Interact to Control Water Table Configurations in a Sub-Humid, Low-Relief Region

NASA Astrophysics Data System (ADS)

Hokanson, K. J.; Devito, K.; Mendoza, C. A.

2017-12-01

The Boreal Plain (BP) region of Canada, a landscape characterized by low-relief, a sub-humid climate and heterogeneous glacial landforms, is experiencing unprecedented anthropogenic and natural disturbance, including climate change and oil & gas operations. Understanding the controls on and the natural variability of water table position, and subsequently predicting changes in water table position under varying physical and climatic scenarios will become important as water security becomes increasingly threatened. The BP is composed of a mosaic of forestland, wetland, and aquatic land covers that contrast in dominant vegetation cover, evapotranspiration, and soil storage that, in turn, influence water table configurations. Additionally, these land-covers overlie heterogeneous glacial landforms with large contrasts in storage and hydraulic properties which, when coupled with wet-dry climate cycles, result in complex water table distributions in time and space. Several forestland-wetland-pond complexes were selected at the Utikuma Research Study Area (URSA) over three distinct surficial geologic materials (glacial fluvial outwash, stagnant ice moraine, lacustrine clay plain) to explore the roles of climate (cumulative departure from the long term yearly mean precipitation), geology, topographic position, and land cover on water table configurations over 15 years (2002 - 2016). In the absence of large groundwater flow systems, local relief and shallow low conductivity substrates promote the formation of near-surface water tables that are less susceptible to climate variation, regardless of topography. Furthermore, in areas of increased storage, wet and dry climate conditions can result in appreciably different water table configurations over time, ranging from mounds to hydraulic depressions, depending on the arrangement of land-covers, dominant surficial geology, and substrate layering.

Transport of E. coli in a sandy soil as impacted by depth to water table.

PubMed

Stall, Christopher; Amoozegar, Aziz; Lindbo, David; Graves, Alexandria; Rashash, Diana

2014-01-01

Septic systems are considered a source of groundwater contamination. In the study described in this article, the fate of microbes applied to a sandy loam soil from North Carolina coastal plain as impacted by water table depth was studied. Soil materials were packed to a depth of 65 cm in 17 columns (15-cm diameter), and a water table was established at 30, 45, and 60 cm depths using five replications. Each day, 200 mL of an artificial septic tank effluent inoculated with E. coli were applied to the top of each column, a 100-mL sample was collected at the water table level and analyzed for E. coli, and 100 mL was drained from the bottom to maintain the water table. Two columns were used as control and received 200 mL/day of sterilized effluent. Neither 30 nor 45 cm of unsaturated soil was adequate to attenuate bacterial contamination, while 60 cm of separation appeared to be sufficient. Little bacterial contamination moved with the water table when it was lowered from 30 to 60 cm.

Effects of soil water table regime on tree community species richness and structure of alluvial forest fragments in Southeast Brazil.

PubMed

Silva, A C; Higuchi, P; van den Berg, E

2010-08-01

In order to determine the influence of soil water table fluctuation on tree species richness and structure of alluvial forest fragments, 24 plots were allocated in a point bar forest and 30 plots in five forest fragments located in a floodplain, in the municipality of São Sebastião da Bela Vista, Southeast Brazil, totalizing 54, 10 X 20 m, plots. The information recorded in each plot were the soil water table level, diameter at breast height (dbh), total height and botanical identity off all trees with dbh > 5 cm. The water table fluctuation was assessed through 1 m deep observation wells in each plot. Correlations analysis indicated that sites with shallower water table in the flooding plains had a low number of tree species and high tree density. Although the water table in the point bar remained below the wells during the study period, low tree species richness was observed. There are other events taking place within the point bar forest that assume a high ecological importance, such as the intensive water velocity during flooding and sedimentation processes.

Estimating steady-state evaporation rates from bare soils under conditions of high water table

USGS Publications Warehouse

Ripple, C.D.; Rubin, J.; Van Hylckama, T. E. A.

1970-01-01

A procedure that combines meteorological and soil equations of water transfer makes it possible to estimate approximately the steady-state evaporation from bare soils under conditions of high water table. Field data required include soil-water retention curves, water table depth and a record of air temperature, air humidity and wind velocity at one elevation. The procedure takes into account the relevant atmospheric factors and the soil's capability to conduct 'water in liquid and vapor forms. It neglects the effects of thermal transfer (except in the vapor case) and of salt accumulation. Homogeneous as well as layered soils can be treated. Results obtained with the method demonstrate how the soil evaporation rates·depend on potential evaporation, water table depth, vapor transfer and certain soil parameters.

Water table and overbank flow frequency changes due to suburbanization-induced channel incision, Virginia Coastal Plain, USA

NASA Astrophysics Data System (ADS)

Hancock, G.; Mattell, N.; Christianson, E.; Wacksman, J.

2004-12-01

Channel incision is a widely observed response to increased flow in urbanized watersheds, but the effects of channel lowering on riparian water tables is not well documented. In a rapidly incising suburban stream in the Virginia Coastal Plain, we hypothesize that incision has lowered floodplain water tables and decreased the overbank flow frequency, and suggest these changes impact vegetation distribution in a diverse, protected riparian habitat. The monitored stream is a tributary to the James River draining 1.3 km2, of which 15% is impervious cover. Incision has occurred largely through upstream migration of a one m high knickpoint at a rate of 1-2 m/yr, primarily during high flow events. We installed 33 wells in six floodplain transects to assess water table elevations beneath the floodplain adjacent to the incising stream. To document the impacts of incision, two transects are located 30 and 50 m upstream of the knickpoint in unincised floodplain, and the remainder are 5, 30, 70, and 100 m downstream of the knickpoint in incised floodplain. In one transect above and two below, pressure transducers attached to dataloggers provide a high-resolution record of water table response to storm events. Significant differences have been observed in the water table above and below the knickpoint. Above the knickpoint, the water table is relatively flat and is 0.2-0.4 m below the floodplain surface. Water table response to precipitation events is nearly immediate, with the water table rising to the floodplain surface in significant rainfall events. In the transect immediately downstream of the knickpoint, the water table possesses a steep gradient, rising from ~1 m below the floodplain at the stream to 0.3 m below the surface within 20 m. In the most downstream transects, the water table is relatively flat, but is one m below the floodplain surface, equivalent to the depth of incision generated by knickpoint passage. Upstream of the knickpoint, overbank flooding occurs frequently, while below the knickpoint the majority of storm flow is contained within the incised channel and occupation of the floodplain is rare. Plant diversity surveys reveal differences in the total density of herbaceous growth and species distribution between the floodplain above and below the knickpoint. Results from >100 plots show that there is more leaf litter, less exposed ground, and a decrease in floodplain species cover in the incised portion of the floodplain. The changes in flood frequency and water table elevation appear to have allowed one invasive species, Japanese stilt grass (Microstegium vimineum), to become dominant in the floodplain understory, displacing native wetland species.

Modelling abstraction licensing strategies ahead of the UK's water abstraction licensing reform

NASA Astrophysics Data System (ADS)

Klaar, M. J.

2012-12-01

Within England and Wales, river water abstractions are licensed and regulated by the Environment Agency (EA), who uses compliance with the Environmental Flow Indicator (EFI) to ascertain where abstraction may cause undesirable effects on river habitats and species. The EFI is a percentage deviation from natural flow represented using a flow duration curve. The allowable percentage deviation changes with different flows, and also changes depending on an assessment of the sensitivity of the river to changes in flow (Table 1). Within UK abstraction licensing, resource availability is expressed as a surplus or deficit of water resources in relation to the EFI, and utilises the concept of 'hands-off-flows' (HOFs) at the specified flow statistics detailed in Table 1. Use of a HOF system enables abstraction to cease at set flows, but also enables abstraction to occur at periods of time when more water is available. Compliance at low flows (Q95) is used by the EA to determine the hydrological classification and compliance with the Water Framework Directive (WFD) for identifying waterbodies where flow may be causing or contributing to a failure in good ecological status (GES; Table 2). This compliance assessment shows where the scenario flows are below the EFI and by how much, to help target measures for further investigation and assessment. Currently, the EA is reviewing the EFI methodology in order to assess whether or not it can be used within the reformed water abstraction licensing system which is being planned by the Department for Environment, Food and Rural Affairs (DEFRA) to ensure the licensing system is resilient to the challenges of climate change and population growth, while allowing abstractors to meet their water needs efficiently, and better protect the environment. In order to assess the robustness of the EFI, a simple model has been created which allows a number of abstraction, flow and licensing scenarios to be run to determine WFD compliance using the current EFI method, as well as allowing alternative licensing scenarios (e.g. using alternative flow statistics, flow periods and ASB bands) to be tested. Initial analysis suggests that the model is a useful tool in visualising licensing options ahead of the licensing reform.Table 1: Percentage allowable abstraction from natural flows at different abstraction sensitivity bands (ASB), as allowed under the EFI method; Table 2: Current framework used to determine flows which support GES as part of the EU WFD;

Elk browsing increases aboveground growth of water-stressed willows by modifying plant architecture.

PubMed

Johnston, Danielle B; Cooper, David J; Hobbs, N Thompson

2007-12-01

In the northern elk wintering range of Yellowstone National Park, USA, wolf (Canis lupus) removal allowed elk (Cervus elaphus) to overbrowse riparian woody plants, leading to the exclusion of beaver (Castor canadensis) and a subsequent water table decline in many small stream valleys. Reduced elk browsing following wolf reintroduction may or may not facilitate willow (Salix sp.) recovery in these areas. To determine if the effect of elk browsing on willow interacts with that of beaver abandonment, we manipulated elk browsing and the water table in a factorial experiment. Under the condition of an ambient (low) water table, elk browsing increased shoot water potential (Psis), photosynthesis per unit leaf area (A), stomatal conductance per unit leaf area (gs), and aboveground current annual growth (CAG) by 50%. Elk browsing occurred entirely during dormancy and did not affect total plant leaf area (L). Improved water balance, photosynthetic rate, and annual aboveground productivity in browsed willows appeared to be due to morphological changes, such as increased shoot diameter and decreased branching, which typically increase plant hydraulic conductivity. An elevated water table increased Psis, A, gs, CAG, and L, and eliminated or lessened the positive effect of browsing on CAG for most species. Because low water tables create conditions whereby high willow productivity depends on the morphological effects of annual elk browsing, removing elk browsing in areas of water table decline is unlikely to result in vigorous willow stands. As large willow standing crops are required by beaver, a positive feedback between water-stressed willow and beaver absence may preclude the reestablishment of historical conditions. In areas with low water table, willow restoration may depend on actions to promote the re-establishment of beaver in addition to reducing elk browsing.

Response of anaerobic carbon cycling to water table manipulation in an Alaskan rich fen

Treesearch

E.S. Kane; M.R. Chivers; M.S. Turetsky; C.C. Treat; D.G. Petersen; M. Waldrop; J.W. Harden; A.D. McGuire

2013-01-01

To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2...

Peatland pines as a proxy for water table fluctuations: disentangling tree growth, hydrology and possible human influence.

PubMed

Smiljanić, Marko; Seo, Jeong-Wook; Läänelaid, Alar; van der Maaten-Theunissen, Marieke; Stajić, Branko; Wilmking, Martin

2014-12-01

Dendrochronological investigations of Scots pine (Pinus sylvestris L.) growing on Männikjärve peatland in central Estonia showed that annual tree growth of peatland pines can be used as a proxy for past variations of water table levels. Reconstruction of past water table levels can help us to better understand the dynamics of various ecological processes in peatlands, e.g. the formation of vegetation patterns or carbon and nitrogen cycling. Männikjärve bog has one of the longest water table records in the boreal zone, continuously monitored since 1956. Common uncertainties encountered while working with peatland trees (e.g. narrow, missing and wedging rings) were in our case exacerbated with difficulties related to the instability of the relationship between tree growth and peatland environment. We hypothesized that the instable relationship was mainly due to a significant change of the limiting factor, i.e. the rise of the water table level due to human activity. To test our hypothesis we had to use several novel methods of tree-ring chronology analysis as well as to test explicitly whether undetected missing rings biased our results. Since the hypothesis that the instable relationship between tree growth and environment was caused by a change in limiting factor could not be rejected, we proceeded to find possible significant changes of past water table levels using structural analysis of the tree-ring chronologies. Our main conclusions were that peatland pines can be proxies to water table levels and that there were several shifting periods of high and low water table levels in the past 200 years. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of vegetation removal and water table drawdown on the non-methane biogenic volatile organic compound emissions in boreal peatland microcosms

NASA Astrophysics Data System (ADS)

Faubert, Patrick; Tiiva, Päivi; Rinnan, Åsmund; Räty, Sanna; Holopainen, Jarmo K.; Holopainen, Toini; Rinnan, Riikka

2010-11-01

Biogenic volatile organic compound (BVOC) emissions are important in the global atmospheric chemistry and their feedbacks to global warming are uncertain. Global warming is expected to trigger vegetation changes and water table drawdown in boreal peatlands, such changes have only been investigated on isoprene emission but never on other BVOCs. We aimed at distinguishing the BVOCs released from vascular plants, mosses and peat in hummocks (dry microsites) and hollows (wet microsites) of boreal peatland microcosms maintained in growth chambers. We also assessed the effect of water table drawdown (-20 cm) on the BVOC emissions in hollow microcosms. BVOC emissions were measured from peat samples underneath the moss surface after the 7-week-long experiment to investigate whether the potential effects of vegetation and water table drawdown were shown. BVOCs were sampled using a conventional chamber method, collected on adsorbent and analyzed with GC-MS. In hummock microcosms, vascular plants increased the monoterpene emissions compared with the treatment where all above-ground vegetation was removed while no effect was detected on the sesquiterpenes, other reactive VOCs (ORVOCs) and other VOCs. Peat layer from underneath the surface with intact vegetation had the highest sesquiterpene emissions. In hollow microcosms, intact vegetation had the highest sesquiterpene emissions. Water table drawdown decreased monoterpene and other VOC emissions. Specific compounds could be closely associated to the natural/lowered water tables. Peat layer from underneath the surface of hollows with intact vegetation had the highest emissions of monoterpenes, sesquiterpenes and ORVOCs whereas water table drawdown decreased those emissions. The results suggest that global warming would change the BVOC emission mixtures from boreal peatlands following changes in vegetation composition and water table drawdown.

Health of native riparian vegetation and its relation to hydrologic conditions along the Mojave River, southern California

USGS Publications Warehouse

Lines, Gregory C.

1999-01-01

The health of native riparian vegetation and its relation to hydrologic conditions were studied along the Mojave River mainly during the growing seasons of 1997 and 1998. The study concentrated on cottonwood?willow woodlands (predominantly Populus fremontii and Salix gooddingii) and mesquite bosques (predominantly Prosopis glandulosa). Tree-growth characteristics were measured at 16 cottonwood?willow woodland sites and at 3 mesquite bosque sites. Density of live and dead trees, tree diameter and height, canopy density, live-crown volume, leaf-water potential, leaf-area index, mortality, and reproduction were measured or noted at each site. The sites included healthy and reproducing woodlands and bosques, stressed woodlands and bosques with no reproduction, and woodlands and bosques with high mortality. Tree roots were studied at seven sites to determine the vertical distribution of the root system and their relation to the water table at healthy, stressed, and high-mortality cottonwood?willow woodlands. In the six trenches that were dug for this study in May 1997, no cottonwood roots were observed that reached the water table. The root systems of healthy trees typically ended 1 to 2 feet above the water table. At sites with high mortality, the main root mass was commonly 7 to 8 feet above the water table. Water-table depth was monitored at each of the study sites. In addition, volumetric soil moisture and soil-water potential were monitored at varying depths at three cottonwood?willow woodland study sites and at two mesquite bosque sites. Ground, soil, river, lake, and plant (xylem sap) water were analyzed for concentrations of stable hydrogen and oxygen isotopes to determine the source of water used by the trees. On the basis of the root-distribution, soil- and leaf-water potential, and isotope data, it was concluded that cottonwood, willow, and mesquite trees mainly rely on ground water for their perennial sustained supply of water. The trees mainly utilize ground water that has moved upward from the water table into the capillary fringe and into unsaturated soil nearer to land surface. Most precipitation (average is 4 to 6 inches per year) is lost by evaporation and by transpiration of shallow-rooted xeric plants, and very little reaches the root zone of trees along the Mojave River. Water-table depth had no strong correlation to many individual tree-growth characteristics, such as density, diameter, height, and live-crown volume. However, leaf-area index (corrected for stem area) of both healthy and stressed cottonwood?willow woodlands had a highly significant statistical relation to water-table depth, and a curvilinear regression model was defined. As in cottonwood?willow woodlands, leaf-area index of mesquite bosques also decreased with increased water-table depth. However, because of the small number of sites, no significant statistical relation could be defined for mesquite bosques. Because it can be accurately measured repeatedly at the same locations, leaf-area index (corrected for stem area) is recommended as the primary growth characteristic that should be monitored. Future vegetation changes along the Mojave River can be quantified using the sites established for this study. Mortality was as high as 39 percent in healthy cottonwood?willow woodlands, but mortality of 50 to 100 percent was common where water-table depth was greater than about 7 feet or in areas where permanent water-table declines greater than about 5 feet had occurred. At a healthy mesquite bosque where the water-table depth ranged from about 8 to 11 feet, mortality was about 20 percent. Where the water table had been lowered an additional 10 to 25 feet by pumping, mortality of the mesquite was extremely high (80 to 99 percent). On the basis of observations of plant reproduction, it was concluded that established cottonwood?willow woodlands probably will reproduce, mainly by root sprouting of mature trees, if the water-t

Field data and numerical simulation of btex concentration trends under water table fluctuations: Example of a jet fuel-contaminated site in Brazil

NASA Astrophysics Data System (ADS)

Teramoto, Elias Hideo; Chang, Hung Kiang

2017-03-01

Mass transfer of light non-aqueous phase liquids (LNAPLs) trapped in porous media is a complex phenomenon. Water table fluctuations have been identified as responsible for generating significant variations in the concentration of dissolved hydrocarbons. Based on field evidence, this work presents a conceptual model and a numerical solution for mass transfer from entrapped LNAPL to groundwater controlled by both LNAPL saturation and seasonal water table fluctuations within the LNAPL smear zone. The numerical approach is capable of reproducing aqueous BTEX concentration trends under three different scenarios - water table fluctuating within smear zone, above the smear zone and partially within smear zone, resulting in in-phase, out-of-phase and alternating in-phase and out-of-phase BTEX concentration trend with respect to water table oscillation, respectively. The results demonstrate the model's applicability under observed field conditions and its ability to predict source zone depletion.

Importance of unsaturated zone flow for simulating recharge in a humid climate

USGS Publications Warehouse

Hunt, R.J.; Prudic, David E.; Walker, J.F.; Anderson, M.P.

2008-01-01

Transient recharge to the water table is often not well understood or quantified. Two approaches for simulating transient recharge in a ground water flow model were investigated using the Trout Lake watershed in north-central Wisconsin: (1) a traditional approach of adding recharge directly to the water table and (2) routing the same volume of water through an unsaturated zone column to the water table. Areas with thin (less than 1 m) unsaturated zones showed little difference in timing of recharge between the two approaches; when water was routed through the unsaturated zone, however, less recharge was delivered to the water table and more discharge occurred to the surface because recharge direction and magnitude changed when the water table rose to the land surface. Areas with a thick (15 to 26 m) unsaturated zone were characterized by multimonth lags between infiltration and recharge, and, in some cases, wetting fronts from precipitation events during the fall overtook and mixed with infiltration from the previous spring snowmelt. Thus, in thicker unsaturated zones, the volume of water infiltrated was properly simulated using the traditional approach, but the timing was different from simulations that included unsaturated zone flow. Routing of rejected recharge and ground water discharge at land surface to surface water features also provided a better simulation of the observed flow regime in a stream at the basin outlet. These results demonstrate that consideration of flow through the unsaturated zone may be important when simulating transient ground water flow in humid climates with shallow water tables.

High-resolution seismic reflection survey at Dover AFB: A comparison of three seismic sources

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

Cardimona, S.; Kadinsky-Cade, K.; Miller, R.

1996-11-01

In June of 1995, the Earth Sciences Division of the Air Force Phillips Lab, with survey equipment from the University of Delaware and assisted by the Kansas Geological Survey and Elohi Geophysics, conducted a geophysical site characterization of the SERDP-funded Groundwater Remediation Field Lab (GRFL) located at Dover AFB, Delaware and administered by Applied Research Associates for USAF Armstrong Lab. Seismic data were collected in order to (1) compare the results using three different compressional sources and (2) cover the field site well enough to characterize the seismic response of the shallow subsurface. This paper will focus primarily on themore » first of these two goals. Seismic data were collected along three north-south profiles set 10 meters apart, each profile with a different compressional source: a 5.5kg sledgehammer, a 12-gauge firing rod from Betsy Seisgun Inc. shooting 150 grain blanks, and a portable piezoelectrically driven vibrator, developed by Elohi Geophysics, operating with a 90Hz-450Hz sweep. An east-west cross line was collected using the sledgehammer source in order to tie the three profiles together. A laser theodolite provided station location and elevation control. The primary targets were the water table (that had been marked on maps at a depth of about 3 meters) and a sand-clay interface at about 15 meters depth. We collected 24-channel CMP data using a half meter spacing of both source and 100Hz geophones. Field C after initial walkaway noise testing with each source did not show any one source to be outstanding A practical early result of the seismic survey showed the water table to be at just over 10 meters. We have associated the strongest reflection event with the water-table interface. Seismic data comparison in this study is based on spectral content, total energy and signal-to-noise ratios, as well as a discussion of coherency of the primary reflection event at the water table.« less

Absorption of the Martian regolith: Specific surface area and missing CO(sub 2)

NASA Technical Reports Server (NTRS)

Zent, A. P.; Fanale, F. P.; Postawko, S. E.

1987-01-01

For most estimates of available regolith and initial degassed CO(sub 2) inventories, it appears that any initial inventory must have been lost to space or incorporated into carbonates. Most estimates of the total available degassed CO(sub 2) inventory are only marginally sufficient to allow for a major early greenhouse effect. It is suggested that the requirements for greenhouse warming to produce old dessicated terrain would be greatly lessened if groundwater brines rather than rainfall were involved and if a higher internal gradient were involved to raise the water (brine) table, leading to more frequent sapping.

Developing Automatic Water Table Control System for Reducing Greenhouse Gas Emissions from Paddy Fields

NASA Astrophysics Data System (ADS)

Arif, C.; Fauzan, M. I.; Satyanto, K. S.; Budi, I. S.; Masaru, M.

2018-05-01

Water table in rice fields play important role to mitigate greenhouse gas (GHG) emissions from paddy fields. Continuous flooding by maintenance water table 2-5 cm above soil surface is not effective and release more GHG emissions. System of Rice Intensification (SRI) as alternative rice farming apply intermittent irrigation by maintaining lower water table is proven can reduce GHG emissions reducing productivity significantly. The objectives of this study were to develop automatic water table control system for SRI application and then evaluate the performances. The control system was developed based on fuzzy logic algorithms using the mini PC of Raspberry Pi. Based on laboratory and field tests, the developed system was working well as indicated by lower MAPE (mean absolute percentage error) values. MAPE values for simulation and field tests were 16.88% and 15.80%, respectively. This system can save irrigation water up to 42.54% without reducing productivity significantly when compared to manual irrigation systems.

Water tables constrain height recovery of willow on Yellowstone's northern range.

PubMed

Bilyeu, Danielle M; Cooper, David J; Hobbs, N Thompson

2008-01-01

Excessive levels of herbivory may disturb ecosystems in ways that persist even when herbivory is moderated. These persistent changes may complicate efforts to restore ecosystems affected by herbivores. Willow (Salix spp.) communities within the northern range in Yellowstone National Park have been eliminated or degraded in many riparian areas by excessive elk (Cervus elaphus L.) browsing. Elk browsing of riparian willows appears to have diminished following the reintroduction of wolves (Canis lupis L.), but it remains uncertain whether reduced herbivory will restore willow communities. The direct effects of elk browsing on willows have been accompanied by indirect effects from the loss of beaver (Castor canadensis Kuhl) activity, including incision of stream channels, erosion of fine sediments, and lower water tables near streams historically dammed by beaver. In areas where these changes have occurred, lowered water tables may suppress willow height even in the absence of elk browsing. We conducted a factorial field experiment to understand willow responses to browsing and to height of water tables. After four years of protection from elk browsing, willows with ambient water tables averaged only 106 cm in height, with negligible height gain in two of three study species during the last year of the experiment. Willows that were protected from browsing and had artificially elevated water tables averaged 147 cm in height and gained 19 cm in the last year of the experiment. In browsed plots, elevated water tables doubled height gain during a period of slightly reduced browsing pressure. We conclude that water availability mediates the rate of willow height gain and may determine whether willows grow tall enough to escape the browse zone of elk and gain resistance to future elk browsing. Consequently, in areas where long-term beaver absence has resulted in incised stream channels and low water tables, a reduction in elk browsing alone may not be sufficient for recovery of tall willow stands. Because tall willow stems are important elements of habitat for beaver, mitigating water table decline may be necessary in these areas to promote recovery of historical willow-beaver mutualisms.

Transient response of Salix cuttings to changing water level regimes

NASA Astrophysics Data System (ADS)

Gorla, L.; Signarbieux, C.; Turberg, P.; Buttler, A.; Perona, P.

2015-03-01

Sustainable water management requires an understanding of the effects of flow regulation on riparian ecomorphological processes. We investigated the transient response of Salix viminalis by examining the effect of water-level regimes on its above-ground and below-ground biomass. Four sets of Salix cuttings, three juveniles (in the first growing season) and one mature (1 year old), were planted and initially grown under the same water-level regime for 1 month. We imposed three different water-level regime treatments representing natural variability, a seasonal trend with no peaks, and minimal flow (characteristic of hydropower) consisting of a constant water level and natural flood peaks. We measured sap flux, stem water potential, photosynthesis, growth parameters, and final root architecture. The mature cuttings were not affected by water table dynamics, but the juveniles displayed causal relationships between the changing water regime, plant growth, and root distribution during a 2 month transient period. For example, a 50% drop in mean sap flux corresponded with a -1.5 Mpa decrease in leaf water potential during the first day after the water regime was changed. In agreement with published field observations, the cuttings concentrated their roots close to the mean water table of the corresponding treatment, allowing survival under altered conditions and resilience to successive stress events. Juvenile development was strongly impacted by the minimum flow regime, leading to more than 60% reduction of both above-ground and below-ground biomass, with respect to the other treatments. Hence, we suggest avoiding minimum flow regimes where Salix restoration is prioritized.

Upland-wetland connectivity provides a significant nexus between isolated wetlands and downstream water bodies

NASA Astrophysics Data System (ADS)

Mclaughlin, D. L.; Kaplan, D. A.; Cohen, M. J.

2013-12-01

Recent rulings by the U.S. Supreme Court have limited federal protection over isolated wetlands, requiring documentation of a 'significant nexus' to a navigable water body to ensure federal jurisdiction. Despite geographic isolation, isolated wetlands influence the surficial aquifer dynamics that regulate baseflow to surface water systems. Due to differences in specific yield (Sy) between upland soils and inundated wetlands, responses of the upland water table to atmospheric fluxes (precipitation, P, and evapotranspiration, ET) are amplified relative to wetland water levels, leading to reversals in the hydraulic gradient between the two systems. As such, wetlands act as a water sink during wet cycles (via wetland exfiltration) and a source (via infiltration) during drier times, regulating both the surficial aquifer and its baseflow to downstream systems. To explore the importance of this wetland function at the landscape scale, we integrated models of soil moisture, upland water table, and wetland stage to simulate the hydrology of a low-relief, depressional landscape. We quantified the hydrologic buffering effect of wetlands by calculating the relative change in the standard deviation (SD) of water table elevation between model runs with and without wetlands. Using this model we explored the effects wetland area and spatial distribution over a range of climatic drivers (P and ET) and soil types. Increasing wetland cumulative area and/or density reduced water table variability relative to landscapes without wetlands, supporting the idea that wetlands stabilize regional hydrologic variation, but also increased mean water table depth because of sustained high ET rates in wetlands during dry periods. Maintaining high cumulative wetland area, but with fewer wetlands, markedly reduced the effect of wetland area, highlighting the importance of small, distributed wetlands on water table regulation. Simulating a range of climate scenarios suggested that the capacity of wetlands to buffer water table variation is most pronounced along a 'sweet spot' where P and ET are relatively balanced. High P and low ET yielded consistently high water tables with wetlands acting predominantly as sinks (i.e., little switching behavior), while low P and high ET scenarios limited wetland inundation. On the other hand, when both P and ET were moderate, the SD of the regional water table was reduced by nearly 50% for landscapes with 30% wetland area distributed over ~1 ha watersheds. Additionally, we found these buffering effects to be stronger in coarser soils compared with finer soils. Considering the strong influence of regional water table on downstream surface water systems, loss of isolated wetland area or mitigation of this loss at the expense of wetland density (i.e., large mitigation banks to replace small distributed systems) has the potential to significantly impact downstream water bodies. Isolated wetlands buffer surficial aquifer dynamics by providing water storage capacitance at the landscape scale and ultimately exert hydraulic regulation of regional surface waters through an indirect, but significant nexus.

Raised Water Tables Affect Southern Hardwood Growth

Treesearch

W. M. Broadfoot

1973-01-01

In natural stands near Demopolis Lock and Dam Reservoir in Alabama, the average growth in tree radius increased about 50 percent in the 5 years after the water table was raised from an indefinite depth to within reach of the tree roots. In natural stands near the Jim Woodruff Reservoir in Florida, radial growth of trees also increased markedly after the water table was...

Recharge characteristics of an unconfined aquifer from the rainfall-water table relationship

NASA Astrophysics Data System (ADS)

Viswanathan, M. N.

1984-02-01

The determination of recharge levels of unconfined aquifers, recharged entirely by rainfall, is done by developing a model for the aquifer that estimates the water-table levels from the history of rainfall observations and past water-table levels. In the present analysis, the model parameters that influence the recharge were not only assumed to be time dependent but also to have varying dependence rates for various parameters. Such a model is solved by the use of a recursive least-squares method. The variable-rate parameter variation is incorporated using a random walk model. From the field tests conducted at Tomago Sandbeds, Newcastle, Australia, it was observed that the assumption of variable rates of time dependency of recharge parameters produced better estimates of water-table levels compared to that with constant-recharge parameters. It was observed that considerable recharge due to rainfall occurred on the very same day of rainfall. The increase in water-table level was insignificant for subsequent days of rainfall. The level of recharge very much depends upon the intensity and history of rainfall. Isolated rainfalls, even of the order of 25 mm day -1, had no significant effect on the water-table levels.

Sulfide mineralization: Its role in chemical weathering of Mars

NASA Technical Reports Server (NTRS)

Burns, Roger G.

1988-01-01

Pyrrhotite-pentlandite assemblages in mafic and ultramafic igneous rocks may have contributed significantly to the chemical weathering reactions that produced degradation products in the Martian regolith. By analogy with terrestrial processes, a model is proposed whereby supergene alteration of these primary Fe-Ni sulfides on Mars has generated secondary sulfides (e.g., pyrite) below the water table and produced acidic groundwater containing high concentrations of dissolved Fe, Ni and sulfate ions. The low pH solutions also initiated weathering reactions of igneous feldspars and ferromagnesian silicates to form clay silicate and ferric oxyhydroxide phases. Near-surface oxidation and hydrolysis of ferric sulfato- and hydroxo-complex ions and sols formed gossans above the water table consisting of poorly crystalline hydrated ferric sulfates (e.g., jarosite), oxides (ferrihydrite, goethite) and silica (opal). Underlying groundwater, now permafrost, contains hydroxo sulfato complexes of Fe, Al, Mg, Ni, etc., which may be stabilized in frozen acidic solutions beneath the surface of Mars. Sublimation of permafrost may replenish colloidal ferric oxides, sulfates and phyllosilicates during dust storms on Mars.

Weathering of sulfides on Mars

NASA Technical Reports Server (NTRS)

Burns, Roger G.; Fisher, Duncan S.

1987-01-01

Pyrrhotite-pentlandite assemblages in mafic and ultramafic igneous rocks may have contributed significantly to the chemical weathering reactions that produce degradation products in the Martian regolith. By analogy and terrestrial processes, a model is proposed whereby supergene alteration of these primary Fe-Ni sulfides on Mars has generated secondary sulfides (e.g., pyrite) below the water table and produced acidic groundwater containing high concentrations of dissolved Fe, Ni, and sulfate ions. The low pH solutions also initiated weathering reactions of igneous feldspars and ferromagnesian silicates to form clay silicate and ferric oxyhydroxide phases. Near-surface oxidation and hydrolysis of ferric sulfato-and hydroxo-complex ions and sols formed gossan above the water table consisting of poorly crystalline hydrated ferric sulfates (e.g., jarosite), oxides (ferrihydrite, goethite), and silica (opal). Underlying groundwater, now permafrost contains hydroxo sulfato complexes of Fe, Al, Mg, Ni, which may be stabilized in frozen acidic solutions beneath the surface of Mars. Sublimation of permafrost may replenish colloidal ferric oxides, sulfates, and phyllosilicates during dust storms on Mars.

Enhancing Groundwater Cost Estimation with the Interpolation of Water Tables across the United States

NASA Astrophysics Data System (ADS)

Rosli, A. U. M.; Lall, U.; Josset, L.; Rising, J. A.; Russo, T. A.; Eisenhart, T.

2017-12-01

Analyzing the trends in water use and supply across the United States is fundamental to efforts in ensuring water sustainability. As part of this, estimating the costs of producing or obtaining water (water extraction) and the correlation with water use is an important aspect in understanding the underlying trends. This study estimates groundwater costs by interpolating the depth to water level across the US in each county. We use Ordinary and Universal Kriging, accounting for the differences between aquifers. Kriging generates a best linear unbiased estimate at each location and has been widely used to map ground-water surfaces (Alley, 1993).The spatial covariates included in the universal Kriging were land-surface elevation as well as aquifer information. The average water table is computed for each county using block kriging to obtain a national map of groundwater cost, which we compare with survey estimates of depth to the water table performed by the USDA. Groundwater extraction costs were then assumed to be proportional to water table depth. Beyond estimating the water cost, the approach can provide an indication of groundwater-stress by exploring the historical evolution of depth to the water table using time series information between 1960 and 2015. Despite data limitations, we hope to enable a more compelling and meaningful national-level analysis through the quantification of cost and stress for more economically efficient water management.

Water-level data from wells and test holes through 1991 and potentiometric contours as of 1991 for Yucca Flat, Nevada Test Site, Nye County, Nevada

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

Hale, G.S.; Trudeau, D.A.; Savard, C.S.

The underground nuclear testing program of the US Department of Energy (USDOE) takes place at the Nevada Test Site (NTS), about 65 mi north-west of Las Vegas, Nevada. Underground nuclear tests at Yucca Flat, one of the USDOE test areas at NTS, have affected hydrologic conditions, including groundwater levels. The purpose of this map report, prepared in cooperation with USDOE, is to present selected water-level data collected from wells and test holes through December 1991, and to show potentiometric contours representing 1991 water-table conditions in the Yucca Flat area. The more generic term, potentiometric contours, is used herein rather thanmore » ``water-table contours`` because the hydrologic units contributing water to wells and test holes may not accurately represent the water table. The water table is that surface in an unconfined water body at which the pressure is atmospheric. It is defined by the altitude at which non- perched ground water is first found in wells and test holes. Perched ground water is defined as unconfined ground water separated from an underlying body of ground water by an unsaturated zone. This map report updates information on water levels in some wells and test holes and the resulting water-table contours in rocks of Cenozoic and Paleozoic age shown by Doty and Thordarson for 1980 conditions.« less

Non-invasive water-table imaging with joint DC-resistivity/microgravity/hydrologic-model inversion

NASA Astrophysics Data System (ADS)

Kennedy, J.; Macy, J. P.

2017-12-01

The depth of the water table, and fluctuations thereof, is a primary concern in hydrology. In riparian areas, the water table controls when and where vegetation grows. Fluctuations in the water table depth indicate changes in aquifer storage and variation in ET, and may also be responsible for the transport and degradation of contaminants. In the latter case, installation of monitoring wells is problematic because of the potential to create preferential flow pathways. We present a novel method for non-invasive water table monitoring using combined DC resistivity and repeat microgravity data. Resistivity profiles provide spatial resolution, but a quantifiable relation between resistivity changes and aquifer-storage changes depends on a petrophysical relation (typically, Archie's Law), with additional parameters and therefore uncertainty. Conversely, repeat microgravity data provide a direct, quantifiable measurement of aquifer-storage change but lack depth resolution. We show how these two geophysical measurements, together with an unsaturated-zone flow model (Hydrogeosphere), effectively constrain the water table position and help identify groundwater-flow model parameters. A demonstration of the method is made using field data collected during the historic 2014 pulse flow in the Colorado River Delta, which shows that geophysical data can effectively constrain a coupled surface-water/groundwater model used to simulate the potential for riparian vegetation germination and recruitment.

In-water recompression.

PubMed

Doolette, David J; Mitchell, Simon J

2018-06-30

Divers suspected of suffering decompression illness (DCI) in locations remote from a recompression chamber are sometimes treated with in-water recompression (IWR). There are no data that establish the benefits of IWR compared to conventional first aid with surface oxygen and transport to the nearest chamber. However, the theoretical benefit of IWR is that it can be initiated with a very short delay to recompression after onset of manifestations of DCI. Retrospective analyses of the effect on outcome of increasing delay generally do not capture this very short delay achievable with IWR. However, in military training and experimental diving, delay to recompression is typically less than two hours and more than 90% of cases have complete resolution of manifestations during the first treatment, often within minutes of recompression. A major risk of IWR is that of an oxygen convulsion resulting in drowning. As a result, typical IWR oxygen-breathing protocols use shallower maximum depths (9 metres' sea water (msw), 191 kPa) and are shorter (1-3 hours) than standard recompression protocols for the initial treatment of DCI (e.g., US Navy Treatment Tables 5 and 6). There has been no experimentation with initial treatment of DCI at pressures less than 285 kPa since the original development of these treatment tables, when no differences in outcomes were seen between maximum pressures of 203 kPa (10 msw) and 285 kPa (18 msw) or deeper. These data and case series suggest that recompression treatment comprising pressures and durations similar to IWR protocols can be effective. The risk of IWR is not justified for treatment of mild symptoms likely to resolve spontaneously or for divers so functionally compromised that they would not be safe in the water. However, IWR conducted by properly trained and equipped divers may be justified for manifestations that are life or limb threatening where timely recompression is unavailable. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.

Reference manual for data base on Nevada water-rights permits

USGS Publications Warehouse

Cartier, K.D.; Bauer, E.M.; Farnham, J.L.

1995-01-01

The U.S. Geological Survey and Nevada Division of Water Resources have cooperatively developed and implemented a data-base system for managing water-rights permit information for the State of Nevada. The Water-Rights Permit data base is part of an integrated system of computer data bases using the Ingres Relational Data-Base Manage-ment System, which allows efficient storage and access to water information from the State Engineer's office. The data base contains a main table, three ancillary tables, and five lookup tables, as well as a menu-driven system for entering, updating, and reporting on the data. This reference guide outlines the general functions of the system and provides a brief description of data tables and data-entry screens.

Streamflow generation in humid West Africa: the role of Bas-fonds investigated with a physically based model of the Critical Zone

NASA Astrophysics Data System (ADS)

Hector, B.; Cohard, J. M.; Séguis, L.

2015-12-01

In West Africa, the drought initiated in the 70's-80's together with intense land-use change due to increasing food demand produced very contrasted responses on water budgets of the critical zone (CZ) depending on the lithological and pedological contexts. In Sahel, streamflow increased, mostly due to increasing hortonian runoff from soil crusting, and so did groundwater storage. On the contrary, in the more humid southern Sudanian area, streamflow decreased and no clear signal has been observed concerning water storage in this hard-rock basement area. There, Bas-fonds are fundamental landscape features. They are seasonally water-logged valley bottoms from which first order streams originate, mostly composed of baseflow. They are a key feature for understanding streamflow generation processes. They also carry an important agronomic potential due to their moisture and nutrient availability. The role of Bas-fond in streamflow generation processes is investigated using a physically-based coupled model of the CZ, ParFlow-CLM at catchment scale (10km²). The model is evaluated against classical hydrological measurements (water table, soil moisture, streamflow, fluxes), acquired in the AMMA-CATCH observing system for the West African monsoon, but also hybrid gravity data which measure integrated water storage changes. The bas-fond system is shown to be composed of two components with different time scales. The slow component is characterized by the seasonal and interannual amplitude of the permanent water table, which is disconnected from streams, fed by direct recharge and lowered by evapotranspiration, mostly from riparian areas. The fast component is characterized by thresholds in storage and perched and permanent water tables surrounding the bas-fond during the wet season, which are linked with baseflow generation. This is a first step toward integrating these features into larger scale modeling of the critical zone for evaluating the effect of precipitation intensification and land use changes scenarios in the area.

Interpolations of groundwater table elevation in dissected uplands.

PubMed

Chung, Jae-won; Rogers, J David

2012-01-01

The variable elevation of the groundwater table in the St. Louis area was estimated using multiple linear regression (MLR), ordinary kriging, and cokriging as part of a regional program seeking to assess liquefaction potential. Surface water features were used to determine the minimum water table for MLR and supplement the principal variables for ordinary kriging and cokriging. By evaluating the known depth to the water and the minimum water table elevation, the MLR analysis approximates the groundwater elevation for a contiguous hydrologic system. Ordinary kriging and cokriging estimate values in unsampled areas by calculating the spatial relationships between the unsampled and sampled locations. In this study, ordinary kriging did not incorporate topographic variations as an independent variable, while cokriging included topography as a supporting covariable. Cross validation suggests that cokriging provides a more reliable estimate at known data points with less uncertainty than the other methods. Profiles extending through the dissected uplands terrain suggest that: (1) the groundwater table generated by MLR mimics the ground surface and elicits a exaggerated interpolation of groundwater elevation; (2) the groundwater table estimated by ordinary kriging tends to ignore local topography and exhibits oversmoothing of the actual undulations in the water table; and (3) cokriging appears to give the realistic water surface, which rises and falls in proportion to the overlying topography. The authors concluded that cokriging provided the most realistic estimate of the groundwater surface, which is the key variable in assessing soil liquefaction potential in unconsolidated sediments. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

Evaluating the value of ENVISAT ASAR Data for the mapping and monitoring of peatland water table depths

NASA Astrophysics Data System (ADS)

Bechtold, Michel; Schlaffer, Stefan

2015-04-01

The Advanced Synthetic Aperture Radar (ASAR) onboard ENVISAT collected C-Band microwave backscatter data from 2005 to 2012. Backscatter in the C-Band depends to a large degree on the roughness and the moisture status of vegetation and soil surface with a penetration depth of ca. 3 cm. In wetlands with stable high water levels, the annual soil surface moisture dynamics are very distinct compared to the surrounding areas, which allows the monitoring of such environments with ASAR data (Reschke et al. 2012). Also in drained peatlands, moisture status of vegetation and soil surface strongly depends on water table depth due to high hydraulic conductivities of many peat soils in the low suction range (Dettmann et al. 2014). We hypothesize that this allows the characterization of water table depths with ASAR data. Here we analyze whether ASAR data can be used for the spatial and temporal estimation of water table depths in different peatlands (natural, near-natural, agriculturally-used and rewetted). Mapping and monitoring of water table depths is of crucial importance, e.g. for upscaling greenhouse gas emissions and evaluating the success of peatland rewetting projects. Here, ASAR data is analyzed with a new map of water table depths for the organic soils in Germany (Bechtold et al. 2014) as well as with a comprehensive data set of monitored peatland water levels from 1100 dip wells and 54 peatlands. ASAR time series from the years 2005-2012 with irregular temporal sampling intervals of 3-14 days were processed. Areas covered by snow were masked. Primary results about the accuracy of spatial estimates show significant correlations between long-term backscatter statistics and spatially-averaged water table depths extracted from the map at the resolution of the ASAR data. Backscatter also correlates with long-term averages of point-scale water table depth data of the monitoring wells. For the latter, correlation is highest between the dry reference backscatter values and summer mean water table depth. Using the boosted regression tree model of Bechtold et al., we evaluate whether the ASAR data can improve prediction accuracy and/or replace parts of ancillary data that is often not available in other countries. In the temporal domain primary results often show a better dependency between backscatter and water table depths compared to the spatial domain. For a variety of vegetation covers the temporal monitoring potential of ASAR data is evaluated at the level of annual water table depth statistics. Bechtold, M., Tiemeyer, B., Laggner, A., Leppelt, T., Frahm, E., and Belting, S., 2014. Large-scale regionalization of water table depth in peatlands optimized for greenhouse gas emission upscaling, Hydrol. Earth Syst. Sci., 18, 3319-3339. Dettmann, U., Bechtold, M., Frahm, E., Tiemeyer, B., 2014. On the applicability of unimodal and bimodal van Genuchten-Mualem based models to peat and other organic soils under evaporation conditions. Journal of Hydrology, 515, 103-115. Reschke, J., Bartsch, A., Schlaffer, S., Schepaschenko, D., 2012. Capability of C-Band SAR for Operational Wetland Monitoring at High Latitudes. Remote Sens. 4, 2923-2943.

Rapid Response of Hydrological Loss of DOC to Water Table Drawdown and Warming in Zoige Peatland: Results from a Mesocosm Experiment

PubMed Central

Lou, Xue-Dong; Zhai, Sheng-Qiang; Kang, Bing; Hu, Ya-Lin; Hu, Li-Le

2014-01-01

A large portion of the global carbon pool is stored in peatlands, which are sensitive to a changing environment conditions. The hydrological loss of dissolved organic carbon (DOC) is believed to play a key role in determining the carbon balance in peatlands. Zoige peatland, the largest peat store in China, is experiencing climatic warming and drying as well as experiencing severe artificial drainage. Using a fully crossed factorial design, we experimentally manipulated temperature and controlled the water tables in large mesocosms containing intact peat monoliths. Specifically, we determined the impact of warming and water table position on the hydrological loss of DOC, the exported amounts, concentrations and qualities of DOC, and the discharge volume in Zoige peatland. Our results revealed that of the water table position had a greater impact on DOC export than the warming treatment, which showed no interactive effects with the water table treatment. Both DOC concentration and discharge volume were significantly increased when water table drawdown, while only the DOC concentration was significantly promoted by warming treatment. Annual DOC export was increased by 69% and 102% when the water table, controlled at 0 cm, was experimentally lowered by −10 cm and −20 cm. Increases in colored and aromatic constituents of DOC (measured by Abs254 nm, SUVA254 nm, Abs400 nm, and SUVA400 nm) were observed under the lower water tables and at the higher peat temperature. Our results provide an indication of the potential impacts of climatic change and anthropogenic drainage on the carbon cycle and/or water storage in a peatland and simultaneously imply the likelihood of potential damage to downstream ecosystems. Furthermore, our results highlight the need for local protection and sustainable development, as well as suggest that more research is required to better understand the impacts of climatic change and artificial disturbances on peatland degradation. PMID:25369065

Relationships among plants, soils and microbial communities along a hydrological gradient in the New Jersey Pinelands, USA

PubMed Central

Yu, Shen; Ehrenfeld, Joan G.

2010-01-01

Background and Aims Understanding the role of different components of hydrology in structuring wetland communities is not well developed. A sequence of adjacent wetlands located on a catenary sequence of soils and receiving the same sources and qualities of water is used to examine specifically the role of water-table median position and variability in affecting plant and microbial community composition and soil properties. Methods Two replicates of three types of wetland found adjacent to each other along a hydrological gradient in the New Jersey Pinelands (USA) were studied. Plant-community and water-table data were obtained within a 100-m2 plot in each community (pine swamp, maple swamp and Atlantic-white-cedar swamp). Monthly soil samples from each plot were analysed for soil moisture, organic matter, extractable nitrogen fractions, N mineralization rate and microbial community composition. Multivariate ordination methods were used to compare patterns among sites within and between data sets. Key Results The maple and pine wetlands were more similar to each other in plant community composition, soil properties and microbial community composition than either was to the cedar swamps. However, maple and pine wetlands differed from each other in water-table descriptors as much as they differed from the cedar swamps. All microbial communities were dominated by Gram-positive bacteria despite hydrologic differences among the sites. Water-table variability was as important as water-table level in affecting microbial communities. Conclusions Water tables affect wetland communities through both median level and variability. Differentiation of both plant and microbial communities are not simple transforms of differences in water-table position, even when other hydrologic factors are kept constant. Rather, soil genesis, a result of both water-table position and geologic history, appears to be the main factor affecting plant and microbial community similarities. PMID:19643908

Rapid response of hydrological loss of DOC to water table drawdown and warming in Zoige peatland: results from a mesocosm experiment.

PubMed

Lou, Xue-Dong; Zhai, Sheng-Qiang; Kang, Bing; Hu, Ya-Lin; Hu, Li-Le

2014-01-01

A large portion of the global carbon pool is stored in peatlands, which are sensitive to a changing environment conditions. The hydrological loss of dissolved organic carbon (DOC) is believed to play a key role in determining the carbon balance in peatlands. Zoige peatland, the largest peat store in China, is experiencing climatic warming and drying as well as experiencing severe artificial drainage. Using a fully crossed factorial design, we experimentally manipulated temperature and controlled the water tables in large mesocosms containing intact peat monoliths. Specifically, we determined the impact of warming and water table position on the hydrological loss of DOC, the exported amounts, concentrations and qualities of DOC, and the discharge volume in Zoige peatland. Our results revealed that of the water table position had a greater impact on DOC export than the warming treatment, which showed no interactive effects with the water table treatment. Both DOC concentration and discharge volume were significantly increased when water table drawdown, while only the DOC concentration was significantly promoted by warming treatment. Annual DOC export was increased by 69% and 102% when the water table, controlled at 0 cm, was experimentally lowered by -10 cm and -20 cm. Increases in colored and aromatic constituents of DOC (measured by Abs(254 nm), SUVA(254 nm), Abs(400 nm), and SUVA(400 nm)) were observed under the lower water tables and at the higher peat temperature. Our results provide an indication of the potential impacts of climatic change and anthropogenic drainage on the carbon cycle and/or water storage in a peatland and simultaneously imply the likelihood of potential damage to downstream ecosystems. Furthermore, our results highlight the need for local protection and sustainable development, as well as suggest that more research is required to better understand the impacts of climatic change and artificial disturbances on peatland degradation.

Effect of water table dynamics on land surface hydrologic memory

NASA Astrophysics Data System (ADS)

Lo, Min-Hui; Famiglietti, James S.

2010-11-01

The representation of groundwater dynamics in land surface models has received considerable attention in recent years. Most studies have found that soil moisture increases after adding a groundwater component because of the additional supply of water to the root zone. However, the effect of groundwater on land surface hydrologic memory (persistence) has not been explored thoroughly. In this study we investigate the effect of water table dynamics on National Center for Atmospheric Research Community Land Model hydrologic simulations in terms of land surface hydrologic memory. Unlike soil water or evapotranspiration, results show that land surface hydrologic memory does not always increase after adding a groundwater component. In regions where the water table level is intermediate, land surface hydrologic memory can even decrease, which occurs when soil moisture and capillary rise from groundwater are not in phase with each other. Further, we explore the hypothesis that in addition to atmospheric forcing, groundwater variations may also play an important role in affecting land surface hydrologic memory. Analyses show that feedbacks of groundwater on land surface hydrologic memory can be positive, negative, or neutral, depending on water table dynamics. In regions where the water table is shallow, the damping process of soil moisture variations by groundwater is not significant, and soil moisture variations are mostly controlled by random noise from atmospheric forcing. In contrast, in regions where the water table is very deep, capillary fluxes from groundwater are small, having limited potential to affect soil moisture variations. Therefore, a positive feedback of groundwater to land surface hydrologic memory is observed in a transition zone between deep and shallow water tables, where capillary fluxes act as a buffer by reducing high-frequency soil moisture variations resulting in longer land surface hydrologic memory.

How Does Tree Density Affect Water Loss of Peatlands? A Mesocosm Experiment

PubMed Central

Limpens, Juul; Holmgren, Milena; Jacobs, Cor M. J.; Van der Zee, Sjoerd E. A. T. M.; Karofeld, Edgar; Berendse, Frank

2014-01-01

Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs. PMID:24632565

Short-term response of methane fluxes and methanogen activity to water table and soil warming manipulations in an Alaskan peatland

Treesearch

M.R. Turetsky; C.C. Treat; M. Waldrop; J.M. Waddington; J.W. Harden; A.D. McGuire

2008-01-01

Growing season CH4 fluxes were monitored over a two year period following the start of ecosystem-scale manipulations of water table position and surface soil temperatures in a moderate rich fen in interior Alaska. The largest CH4 fluxes occurred in plots that received both flooding (raised water table position) and soil...

Sensitivity of stream flow and water table depth to potential climatic variability in a coastal forested watershed

Treesearch

Zhaohua Dai; Carl Trettin; Changsheng Li; Devendra M. Amatya; Ge Sun; Harbin Li

2010-01-01

A physically based distributed hydrological model, MIKE SHE, was used to evaluate the effects of altered temperature and precipitation regimes on the streamflow and water table in a forested watershed on the southeastern Atlantic coastal plain. The model calibration and validation against both streamflow and water table depth showed that the MIKE SHE was applicable for...

Effect of Unsaturated Flow on Delayed Response of Unconfined Aquifiers to Pumping

NASA Astrophysics Data System (ADS)

Tartakovsky, G.; Neuman, S. P.

2005-12-01

A new analytical solution is presented for the delayed response process characterizing flow to a partially penetrating well in an unconfined aquifer. The new solution generalizes that of Neuman [1972, 1974] by accounting for unsaturated flow above the water table. Axially symmetric three-dimensional flow in the unsaturated zone is described by a linearized version of Richards' equation in which hydraulic conductivity and water content vary exponentially with incremental capillary pressure head relative to its air entry value (defining the interface between the saturated and unsaturated zones). Unsaturated soil properties are characterized by an exponent κ having the dimension of inverse length and a dimensionless exponent κD = κb where b is initial saturated thickness. Our treatment of the unsaturated zone is similar to that of Kroszynski and Dagan [1975] who however have ignored internal (artesian) aquifer storage. It has been suggested by Boulton [1954, 1963, 1970] and Neuman [1972, 1974], and is confirmed by our solution, that internal storage is required to reproduce the early increase in drawdown characterizing delayed response to pumping in typical aquifers. According to our new solution such aquifers are characterized by relatively large κ_ D values, typically 10 or larger; in the limit as κD tends to infinity (the soil unsaturated water retention capacity becomes insignificant and/or aquifer thickness become large), unsaturated flow becomes unimportant and our solution reduces to that of Neuman. In typical cases corresponding to κD larger than or equal to 10, unsaturated flow is found to have little impact on early and late dimensionless time behaviors of drawdown measured wholly or in part at some distance below the water table; unsaturated flow causes drawdown to increase slightly at intermediate dimensionless time values that represent transition from an early artesian dominated to a late water-table dominated flow regime. The increase in drawdown during this transition period is caused by delayed drainage from the unsaturated zone, whose relatively small effect is superimposed on the more pronounced phenomenon of delay in water table decline relative to artesian head drops below it. Delayed drainage from the unsaturated zone becomes less and less important as κD increases; as it approaches infinity, this effect dies out completely and drawdown is controlled entirely by delayed decline in the water table. The unsaturated zone has major impact on drawdown at intermediate time, and significant impact at early and late times, in the atypical case of small κD values (1 or less), becoming the dominant factor as κD approaches zero (the soil water retention capacity becomes very large and/or saturated thickness becomes insignificant).

Altitude of the water table in the alluvial and Wilcox aquifers in the vicinity of Richland and Tehuacana creeks and the Trinity River, Texas, December 1979

USGS Publications Warehouse

Garza, Sergio

1980-01-01

This map shows the altitude of the water table in the alluvial and Wilcox aquifers in the vicinity of Richland and Tehuacana Creeks and the Trinity River, Tex., in December 1979. The water-table contours were constructed on the basis of water-level control derived from an inventory of shallow wells in the area, topographic maps, and field locations of numerous small springs and seeps. (USGS)

Management Approaches for Water Quality Enhancement at Whitney Point and East Sidney Lake, New York

DTIC Science & Technology

1990-08-01

flos- aguae Anabaena sp. (colonial blue-greens) 8-16-88 Aphanizomenon flos- aguae Anabaena planctonica Coccoid sp. (colonial blue-greens...Goelosphaeriui sp. Microcystis aerug~inosa Comphosphaeria sp. 9-9-88 Aphanizomenon flos- aguae Oscillatoria sp. Melosira spp. Table 9 Dominant Phytoplankton Species...study (Kennedy et al. 1988). Sampling period was initiated in early April, 1988 and completed in early September, 1988. In situ variables, measured at

Data Tables - Environments and Contaminants - Drinking Water Contaminants

EPA Pesticide Factsheets

This document contains a table of the estimated percentage of children ages 0 to 17 years served by community water systems that did not meet all applicable health-based drinking water standards, 1993-2009.

Field data and numerical simulation of btex concentration trends under water table fluctuations: Example of a jet fuel-contaminated site in Brazil.

PubMed

Teramoto, Elias Hideo; Chang, Hung Kiang

2017-03-01

Mass transfer of light non-aqueous phase liquids (LNAPLs) trapped in porous media is a complex phenomenon. Water table fluctuations have been identified as responsible for generating significant variations in the concentration of dissolved hydrocarbons. Based on field evidence, this work presents a conceptual model and a numerical solution for mass transfer from entrapped LNAPL to groundwater controlled by both LNAPL saturation and seasonal water table fluctuations within the LNAPL smear zone. The numerical approach is capable of reproducing aqueous BTEX concentration trends under three different scenarios - water table fluctuating within smear zone, above the smear zone and partially within smear zone, resulting in in-phase, out-of-phase and alternating in-phase and out-of-phase BTEX concentration trend with respect to water table oscillation, respectively. The results demonstrate the model's applicability under observed field conditions and its ability to predict source zone depletion. Copyright © 2017 Elsevier B.V. All rights reserved.

Environmental factors controlling methane emissions from peatlands in northern Minnesota

NASA Technical Reports Server (NTRS)

Dise, Nancy B.; Gorham, Eville; Verry, Elon S.

1993-01-01

The environmental factors affecting the emission of methane from peatlands were investigated by correlating CH4 emission data for two years, obtained from five different peatland ecosystems in northern Minnesota, with peat temperature, water table position, and degree of peat humification. The relationship obtained between the CH4 flux and these factors was compared to results from a field manipulation experiment in which the water table was artificially raised in three experimental plots within the driest peatland. It was found that peat temperature, water table position, and degree of peat humification explained 91 percent of the variance in log CH4 flux, successfully predicted annual CH4 emission from individual wetlands, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased CH4 emission by 2.5 and 2.2 times, respectively.

Paleoclimatic Inferences from a 120,000-Yr Calcite Record of Water-Table Fluctuation in Browns Room of Devils Hole, Nevada

USGS Publications Warehouse

Szabo, B. J.; Kolesar, Peter T.; Riggs, A.C.; Winograd, I.J.; Ludwig, K. R.

1994-01-01

The petrographic and morphologic differences between calcite precipitated below, at, or above the present water table and uranium-series dating were used to reconstruct a chronology of water-table fluctuation for the past 120,000 yr in Browns Room, a subterranean air-filled chamber of Devils Hole fissure adjacent to the discharge area of the large Ash Meadows groundwater flow system in southern Nevada. The water table was more than 5 m above present level between about 116,000 and 53,000 yr ago, fluctuated between about +5 and +9 m during the period between about 44,000 and 20,000 yr ago, and declined rapidly from +9 to its present level during the past 20,000 yr. Because the Ash Meadows groundwater basin is greater than 12,000 km2 in extent, these documented water-table fluctuations are likely to be of regional significance. Although different in detail, water-level fluctuation recorded by Browns Room calcites generally correlate with other Great Basin proxy palcoclimatic data.

Basement flooding and foundation damage from water-table rise in the East New York section of Brooklyn, Long Island, New York

USGS Publications Warehouse

Soren, Julian

1976-01-01

A rising water table following cessation of public-supply pumping has been causing basement flooding and building-foundation damage in the East New York section of Brooklyn, Kings County, Long Island, N.Y., since 1975. The water table in the central part of the area rose from a low of about 12 feet (3.7 meters) below sea level in 1936 to about 8 to 10 feet (2.4 to 3 meters) above sea level in March 1976. Public-supply pumping in Brooklyn ceased in 1947 and ceased in 1974 in the adjacent Woodhaven section of Queens County. A further water-table rise of about 2 feet (0.6 meter) is anticipated in the next several years in the central part of the East New York area, and the ultimate water-table height could be as much as about 15 feet (4.6 meters) above sea level. Relief from the flooding by dewatering operations is complicated by problems with disposal of pumped-out ground water. (Woodard-USGS)

Summary of Part 75 Administrative Processes: Table 1

EPA Pesticide Factsheets

Learn how to submit your initial certification, recertification, monitoring plans, routine quality assurance tests, diagnostic tests and DAHS verifications, low mass emissions units and other notification requirements. Table 1, initial certification.

Hydrologic data; North Canadian River from Lake Overholser to Lake Eufaula, central Oklahoma

USGS Publications Warehouse

Havens, J.S.

1984-01-01

The data contained in this report were gathered during the period 1982 to 1984 for use in constructing a digital model of the North Canadian River from Lake Overholser, in the western part of Oklahoma City, to Lake Eufaula, in eastern Oklahoma. Locations of test holes and sampling sites are show in figure 1. Information on well depths and water levels in table 1 was gathered in the summer of 1982. Some information in the table was reported by well owners. Field water-quality data for water temperatures, specific conductance, and pH were measured at the time the wells were inventoried in 1982 and appear in table 2. Forty-nine test holes were augered to provide more comprehensive lithologic and water-level data along the North Canadian River. Lithologic logs of these test holes appear in table 3. Thirty-eight of the test holes were completed as observations wells by placing perforated plastic casing in the holes. Water levels were measured in these observations wells from the time of completion in mid-1982 through mid-1984. Hydrographs of the observation wells are shown in figures 2 through 15. The data are presented graphically for clarity. Hydrographs of water-level fluctuations in two wells equipped with continuous water-level recorders and hydrographs of stage fluctuations on the North Canadian River at nearby gaging stations are shown in figures 16 and 17. Two sets of low-flow measurements for the North Canadian River showing gains and losses in flow between measuring sites in the reach from Lake Overholser to Lake Eufaula are given in table 4. Measurements of flow on tributary streams are also given in this table. Analyses of water-quality samples collected at the time of the low-flow measurements are given in table 5.

41. PATTERN STORAGE, GRIND STONE, WATER TANK, SHAFTING, AND TABLE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. PATTERN STORAGE, GRIND STONE, WATER TANK, SHAFTING, AND TABLE SAW (L TO R)-LOOKING WEST. - W. A. Young & Sons Foundry & Machine Shop, On Water Street along Monongahela River, Rices Landing, Greene County, PA

Treatment of table olive washing water using trickling filters, constructed wetlands and electrooxidation.

PubMed

Tatoulis, Triantafyllos; Stefanakis, Alexandros; Frontistis, Zacharias; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Mantzavinos, Dionissios; Vayenas, Dimitrios V

2017-01-01

The production of table olives is a significant economic activity in Mediterranean countries. Table olive processing generates large volumes of rinsing water that are characterized by high organic matter and phenol contents. Due to these characteristics, a combination of more than one technology is imperative to ensure efficient treatment with low operational cost. Previously, biological filters were combined with electrooxidation to treat table olive washing water. Although this combination was successful in reducing pollutant loads, its cost could be further reduced. Constructed wetlands could be an eligible treatment method for integrated table olive washing water treatment as they have proved tolerant to high organic matter and phenol loads. Two pilot-scale horizontal subsurface constructed wetlands, one planted and one unplanted, were combined with a biological filter and electrooxidation over a boron-doped diamond anode to treat table olive washing water. In the biological filter inlet, chemical oxygen demand (COD) concentrations ranged from 5500 to 15,000 mg/L, while mean COD influent concentration in the constructed wetlands was 2800 mg/L. The wetlands proved to be an efficient intermediate treatment stage, since COD removal levels for the planted unit reached 99 % (mean 70 %), while the unplanted unit presented removal rates of around 65 %. Moreover, the concentration of phenols in the effluent was typically below 100 mg/L. The integrated trickling filter-constructed wetland-electrooxidation treatment system examined here could mineralize and decolorize table olive washing water and fully remove its phenolic content.

Seasonal changes in ground-water levels in the shallow aquifer near Hagerman and the Pecos River, Chaves County, New Mexico

USGS Publications Warehouse

Garn, H.S.

1988-01-01

The Pecos River near Hagerman in Chaves County, New Mexico, historically has been a gaining stream. In 1938, the slope of the water table in the shallow alluvial aquifer near Hagerman was toward the Pecos River. By 1950, a large water-table depression had formed in the alluvial aquifer southwest of Hagerman. Continued enlargement of this depression could reverse the direction of groundwater flow to the Pecos River. Water levels were measured during 1981-85 in wells along a section extending from the Pecos River to a point within the depression. Although the water-table depression has not caused a perennial change in direction of groundwater flow, it has caused a seasonal reversal in the slope of the water table between the river and the depression during the growing season when pumpage from the shallow aquifer is the greatest. (USGS)

Excess growing-season water limits lowland black spruce productivity

NASA Astrophysics Data System (ADS)

Dymond, S.; Kolka, R. K.; Bolstad, P. V.; Gill, K.; Curzon, M.; D'Amato, A. W.

2015-12-01

The annual growth of many tree species is limited by water availability, with growth increasing as water becomes less scarce. In lowland bogs of northern Minnesota, however, black spruce (Picea mariana) is often exposed to excess water via high water table elevations. These trees grow in thick deposits of organic mucky peat and often have shallow rooting systems to avoid the complete submersion of roots in water. While it is generally believed that black spruce decrease growth rates with rising water table elevations, this hypothesis has not been tested in situ. We used a unique, 50-year record of daily bog water table elevations at the Marcell Experimental Forest (MEF) in northern Minnesota to investigate the relationship between climate and black spruce productivity. Nine 1/20th ha circular plots were established in five different bogs and tree height, diameter-at-breast-height (DBH), and crown class were recorded. Additionally, two perpendicular cores were collected on all trees greater than 10 cm diameter-at-breast-height. Tree cores were sanded, mounted, cross-dated, and de-trended according to standard dendrochronological procedures. Ring width measurements were correlated with precipitation, temperature, and water table elevation using package BootRes in R to determine the climatic variables most associated with stand level productivity. Across the different plots, we found that early growing season water table elevation (May and June) was negatively correlated with both individual and stand-level black spruce growth (p < 0.01), while growth was positively correlated with March temperatures (p < 0.01). No significant relationships existed between black spruce growth and monthly precipitation. If summer water table elevations in these peatland ecosystems rise as is anticipated with more extreme precipitation events due to climate change, we could see an overall decrease in the stand level productivity of black spruce.

VizieR Online Data Catalog: Stellar yields and the initial mass function (Molla+, 2015)

NASA Astrophysics Data System (ADS)

Molla, M.; Cavichia, O.; Gavilan, M.; Gibson, B. K.

2017-10-01

These tables give the theoretical chemical evolution models applied for the Milky Way Galaxy (MWG) from the cited paper. Basically give tables 2, 4 of stellar yields used and results of table 6 for the 144 models computed that work. Tables 2 and 4 give the stellar yields q_i(m) and remmnant mass for low and intermediate stars and massive stars, respectively, in a similar format for all authors. Table 6 gives the value of Chi2 for the 144 models computed for MWG using those stellar yields and different Initial Mass Function (see paper). Moreover, we give the table with results of the present time state of the Galactic disk for these 144 models. (12 data files).

Experimental response of Salix cuttings to different flow regimes due to human activities

NASA Astrophysics Data System (ADS)

Gorla, Lorenzo; Signarbieux, Constant; Turberg, Pascal; Buttler, Alexandre; Perona, Paolo

2014-05-01

Hydropower production and other human activities change the natural flow regime of rivers, in turn impacting the riparian environment. The main challenge in order to define eco-sustainable flows is to quantify the effects in terms of geomorphology and ecosystem adaptation. We present 2-years controlled experiments to investigate riparian vegetation (Salix Viminalis) response to forced water table changing dynamics, from one water regime to another, in a temperate region (Switzerland). Three synthetic flow regimes have been simulated and applied to three batteries of Salix cuttings growing outdoor within plastic pots, each about 1 meter tall. In 2012 one treatment simulated a minimal flow policy for small run-of-river hydropower plants, which drastically impacts the low and the medium-low components of the hydrograph, but not the extremes. In 2013 we confirmed and completed some of 2012 results, by reproducing typical hydropeaking effects due to dam management and focusing on daily water table variations and offsets. For both the seasons, after an initial period where all pots undergone the same oscillations in order to uniform the plants initial conditions, the experiment started, and the water dynamic was changed. Cuttings transitory response dynamics has been quantified by continuous sap flow and water potential measurements, and by regularly collecting growth parameters, as well as leaves photosynthesis, fluorescence, and pictures of each plant. At the end of the experiment, all cuttings were carefully removed and the both above and below ground biomass analyzed in detail. Particularly, the 3D root structure was obtained by High Resolution Computer Tomography. Our analyses revealed a clear dependence between roots distribution and water regime reflecting the need for adaptation, in agreement with field observations of Pasquale et al. (2012). In particular, an initial strong difference in terms of stress and growth performances was then followed by a later adjustment in the roots system, notably detected from tomographic images. Macroscopic effects in terms of growth parameters at weekly time step have found correspondence at higher time resolution in terms of sap flow and stem pressure, strengthening our results interpretation. REFERENCES - Pasquale et al. "Effects of streamflow variability on the vertical root density distribution of willow cutting experiments." Ecological Engineering 40 (2012): 167-172. - Gorla et al., "Transient response of Salix cuttings to changing water level regimes", WRR, submitted.

Groundwater Monitoring Plan. Volume 2. Final Quality Assurance Project Plan

DTIC Science & Technology

1993-10-01

5 Table 4-2. US EPA Drinking Water MCLs ........................................ 4-6 Table 5-1. Sample Bottle Requirements, Preservation, and Holding... drinking water . " The types of quality control samples that will be collected during the Canal Creek groundwater monitoring program. ]- Jacobs...Revision No.: 0 Date: 10/27/93 Page: 6 of 9 Canal Creek Area, APG-EA, Maryland Groundwater Monitoring Plan, VOLUME I1 Table 4-2. US EPA Drinking Water

Water table tests of proposed heat transfer tunnels for small turbine vanes

NASA Technical Reports Server (NTRS)

Meitner, P. L.

1974-01-01

Water-table flow tests were conducted for proposed heat-transfer tunnels which were designed to provide uniform flow into their respective test sections of a single core engine turbine vane and a full annular ring of helicopter turbine vanes. Water-table tests were also performed for the single-vane test section of the core engine tunnel. The flow in the heat-transfer tunnels was shown to be acceptable.

--No Title--

Science.gov Websites

| |----------|--------|----------------------------------------------------------| | | | | | GFSCLS1 | A60243 | TABLE A ENTRY - GFSMODEL MESSAGES | | | | | | HEADR | 362001 | TABLE D ENTRY - PROFILE COORDINATES | | PROFILE | 362002 | TABLE D ENTRY - PROFILE DATA | | CLS1 | 362003 | TABLE D ENTRY - SURFACE | TABLE B ENTRY - SNOW WATER EQUIVALENT | | LCLD | 020051 | TABLE B ENTRY - AMOUNT OF LOW CLOUD | | MCLD

40 CFR 132.3 - Adoption of criteria.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) The acute water quality criteria for protection of aquatic life in Table 1 of this part, or a site... water quality criteria for protection of aquatic life in Table 2 of this part, or a site-specific....3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY...

Installation Restoration Program. Preliminary Assessment: Record Search for the 110th Tactical Air Support Group, Michigan Air National Guard, W. K. Kellogg Regional Airport, Battle Creek, Michigan.

DTIC Science & Technology

1987-09-01

these wetlands. Because of the generally low relief at the Base, several manmade drainage ditches have been constructed to improve surface water ...northerly boundary (Hickock, 1985). Within the Marshall Formation, the water table or piezometric surface con- forms somewhat to the land surface. The...34hills" in the water table underlie hills seen on land. The " lows " in the water table coincide with low areas on land (Vanlier, 1966). Thus, the

Water table in rocks of Cenozoic and Paleozoic age, 1980, Yucca Flat, Nevada Test Site, Nevada

USGS Publications Warehouse

Doty, G.C.; Thordarson, William

1983-01-01

The water table at Yucca Flat, Nevada Test Site, Nevada, occurs in rocks of Paleozoic age and in tuffs and alluvium of Cenozoic age and ranges in altitude from about 2,425 feet to about 3,500 feet. The configuration of the water table is depicted by contours with intervals of 25 to 500 feet. Control for the map consists of water-level information from 61 drill holes, whose locations and age of geologic units penetrated are shown by symbols on the map. (USGS)

A study on the influence of tides on the water table conditions of the shallow coastal aquifers

NASA Astrophysics Data System (ADS)

Singaraja, C.; Chidambaram, S.; Jacob, Noble

2018-03-01

Tidal variation and water level in aquifer is an important function in the coastal environment, this study attempts to find the relationship between water table fluctuation and tides in the shallow coastal aquifers. The study was conducted by selecting three coastal sites and by monitoring the water level for every 2-h interval in 24 h of observation. The study was done during two periods of full moon and new moon along the Cuddalore coastal region of southern part of Tamil Nadu, India. The study shows the relationship between tidal variation, water table fluctuations, dissolved oxygen, and electrical conductivity. An attempt has also been made in this study to approximate the rate of flow of water. Anyhow, the differences are site specific and the angle of inclination of the water table shows a significant relation to the mean sea level, with respect to the distance of the point of observation from the sea and elevation above mean sea level.

Ecohydrological controls over water budgets in floodplain meadows

NASA Astrophysics Data System (ADS)

Morris, Paul J.; Verhoef, Anne; Macdonald, David M. J.; Gardner, Cate M.; Punalekar, Suvarna M.; Tatarenko, Irina; Gowing, David

2013-04-01

Floodplain meadows are important ecosystems, characterised by high plant species richness including rare species. Fine-scale partitioning along soil hydrological gradients allows many species to co-exist. Concerns exist that even modest changes to soil hydrological regime as a result of changes in management or climate may endanger floodplain meadows communities. As such, understanding the interaction between biological and physical controls over floodplain meadow water budgets is important to understanding their likely vulnerability or resilience. Floodplain meadow plant communities are highly heterogeneous, leading to patchy landscapes with distinct vegetation. However, it is unclear whether this patchiness in plant distribution is likely to translate into heterogeneous soil-vegetation-atmosphere transfer (SVAT) rates of water and heat, or whether floodplain meadows can reasonably be treated as internally homogeneous in physical terms despite this patchy vegetation. We used a SVAT model, the Soil-Water-Atmosphere-Plants (SWAP) model by J.C. van Dam and co-workers, to explore the controls over the partitioning of water budgets in floodplain meadows. We conducted our research at Yarnton Mead on the River Thames in Oxfordshire, one of the UK's best remaining examples of a floodplain meadow, and which is still managed and farmed in a low-intensity mixed-use manner. We used soil and plant data from our site to parameterise SWAP; we drove the model using in-situ half-hourly meteorological data. We analysed the model's sensitivity to a range of soil and plant parameters - informed by our measurements - in order to assess the effects of different plant communities on SVAT fluxes. We used a novel method to simulate water-table dynamics at the site; the simulated water tables provide a lower boundary condition for SWAP's hydrological submodel. We adjusted the water-table model's parameters so as to represent areas of the mead with contrasting topography, and so different heights above the river level and different moisture and drainage regimes. The model was most sensitive to changes in the parameters that define the water-table model. Plant above-ground parameters, such as leaf area index and canopy height also had strong influences on simulated fluxes. The model exhibited low sensitivity to plant root parameters; this was particularly true during wet periods when the simulated plant communities were oxygen stressed. Changes in soil texture profile exhibited an intermediate level of control over SVAT fluxes. Our findings indicate that unlike in environments with deep water tables, such as drylands and headwater basins, high-quality water-table data with decimetre or even centimetre accuracy are important to accurate simulation of SVAT fluxes. Future studies that seek to simulate SVAT fluxes in shallow groundwater systems should either use high frequency, high-quality water-table observations as part of the driving data set, or should ensure that water-table dynamics and their interactions with surface processes can be simulated in a robust and physically meaningful manner. The low sensitivity of our model to plant root parameters reflects the proximity of the water table to the ground surface and the fact that the simulated plant community is rarely water-stressed, and again contrasts with findings from existing SVAT model research in environments with deep water tables.

Seasonal variability of near surface soil water and groundwater tables in Florida : phase II.

DOT National Transportation Integrated Search

2008-01-01

The seasonal high groundwater table (SHGWT) is a critical measure for design projects requiring : surface water permits including roadway design and detention or retention pond design. Accurately : measuring and, more importantly, predicting water ta...

Hydrologic processes governing near surface saturation of alpine wetlands in the Canadian Rockies

NASA Astrophysics Data System (ADS)

Westbrook, C.; Mercer, J.

2016-12-01

Alpine wetlands are vital for habitat, biodiversity, carbon cycling and water storage, but little is known about their hydrologic condition. Climate trends toward smaller mountain snowpacks that melt earlier are thought to pose a threat to the continued provision of alpine wetland ecological functions, and their existence, as it is believed they derive their water mainly from snowmelt. Our objective was to determine the hydrologic processes governing near surface saturation in alpine wetlands. We monitored the water table dynamics of three alpine wetlands in contrasting hydrogeomorphic landscape positions for two summers in Banff National Park, Canada. We concurrently monitored water balance components, and analyzed soil properties and source water geochemistry. Despite very different snow conditions between the two study years, water tables remained near the surface and relatively stable in both years, indicating wetlands are more hydrologically buffered from snowpack variations than expected. We did not find convincing evidence of hydrogeomorphic position influencing wetland water table dynamics. Instead, peat thickness seemed to be critical in regulating water table as the wetland with the thickest peat soil (>1 m) maintained water tables closest to the ground surface for the longest period of time. Thicker peat deposits may develop under convergent hydrologic flow path conditions. Our results indicate that alpine wetlands are more resilient to shifting environmental conditions than previously reported.

The Impact of Water Table Drawdown and Drying on Subterranean Aquatic Fauna in In-Vitro Experiments

PubMed Central

Stumpp, Christine; Hose, Grant C.

2013-01-01

The abstraction of groundwater is a global phenomenon that directly threatens groundwater ecosystems. Despite the global significance of this issue, the impact of groundwater abstraction and the lowering of groundwater tables on biota is poorly known. The aim of this study is to determine the impacts of groundwater drawdown in unconfined aquifers on the distribution of fauna close to the water table, and the tolerance of groundwater fauna to sediment drying once water levels have declined. A series of column experiments were conducted to investigate the depth distribution of different stygofauna (Syncarida and Copepoda) under saturated conditions and after fast and slow water table declines. Further, the survival of stygofauna under conditions of reduced sediment water content was tested. The distribution and response of stygofauna to water drawdown was taxon specific, but with the common response of some fauna being stranded by water level decline. So too, the survival of stygofauna under different levels of sediment saturation was variable. Syncarida were better able to tolerate drying conditions than the Copepoda, but mortality of all groups increased with decreasing sediment water content. The results of this work provide new understanding of the response of fauna to water table drawdown. Such improved understanding is necessary for sustainable use of groundwater, and allows for targeted strategies to better manage groundwater abstraction and maintain groundwater biodiversity. PMID:24278111

Estimating drain flow from measured water table depth in layered soils under free and controlled drainage

NASA Astrophysics Data System (ADS)

Saadat, Samaneh; Bowling, Laura; Frankenberger, Jane; Kladivko, Eileen

2018-01-01

Long records of continuous drain flow are important for quantifying annual and seasonal changes in the subsurface drainage flow from drained agricultural land. Missing data due to equipment malfunction and other challenges have limited conclusions that can be made about annual flow and thus nutrient loads from field studies, including assessments of the effect of controlled drainage. Water table depth data may be available during gaps in flow data, providing a basis for filling missing drain flow data; therefore, the overall goal of this study was to examine the potential to estimate drain flow using water table observations. The objectives were to evaluate how the shape of the relationship between drain flow and water table height above drain varies depending on the soil hydraulic conductivity profile, to quantify how well the Hooghoudt equation represented the water table-drain flow relationship in five years of measured data at the Davis Purdue Agricultural Center (DPAC), and to determine the impact of controlled drainage on drain flow using the filled dataset. The shape of the drain flow-water table height relationship was found to depend on the selected hydraulic conductivity profile. Estimated drain flow using the Hooghoudt equation with measured water table height for both free draining and controlled periods compared well to observed flow with Nash-Sutcliffe Efficiency values above 0.7 and 0.8 for calibration and validation periods, respectively. Using this method, together with linear regression for the remaining gaps, a long-term drain flow record for a controlled drainage experiment at the DPAC was used to evaluate the impacts of controlled drainage on drain flow. In the controlled drainage sites, annual flow was 14-49% lower than free drainage.

An analytical solution for predicting the transient seepage from a subsurface drainage system

NASA Astrophysics Data System (ADS)

Xin, Pei; Dan, Han-Cheng; Zhou, Tingzhang; Lu, Chunhui; Kong, Jun; Li, Ling

2016-05-01

Subsurface drainage systems have been widely used to deal with soil salinization and waterlogging problems around the world. In this paper, a mathematical model was introduced to quantify the transient behavior of the groundwater table and the seepage from a subsurface drainage system. Based on the assumption of a hydrostatic pressure distribution, the model considered the pore-water flow in both the phreatic and vadose soil zones. An approximate analytical solution for the model was derived to quantify the drainage of soils which were initially water-saturated. The analytical solution was validated against laboratory experiments and a 2-D Richards equation-based model, and found to predict well the transient water seepage from the subsurface drainage system. A saturated flow-based model was also tested and found to over-predict the time required for drainage and the total water seepage by nearly one order of magnitude, in comparison with the experimental results and the present analytical solution. During drainage, a vadose zone with a significant water storage capacity developed above the phreatic surface. A considerable amount of water still remained in the vadose zone at the steady state with the water table situated at the drain bottom. Sensitivity analyses demonstrated that effects of the vadose zone were intensified with an increased thickness of capillary fringe, capillary rise and/or burying depth of drains, in terms of the required drainage time and total water seepage. The analytical solution provides guidance for assessing the capillary effects on the effectiveness and efficiency of subsurface drainage systems for combating soil salinization and waterlogging problems.

Ground-water data, Sevier Desert, Utah

USGS Publications Warehouse

Mower, Reed W.; Feltis, Richard D.

1964-01-01

This report is intended to serve two purposes: (1) to make available to the public basic ground-water data useful in planning and studying development of water resources, and (2) to supplement an interpretive report that will be published later.Records were collected during the period 1935-64 by the U.S. Geological survey in cooperation with the Utah State Engineer as part of the investigation of ground-water conditions in the Sevier Desert, in Juab and Millard Counties, Utah. The interpretive material will be published in a companion report by R. W. Mower and R. D. Feltis.This report is most useful in predicting conditions likely to be found in areas that are being considered as well sites. The person considering the new well can spot the proposed site on plate 1 and examine the records of nearby wells as shown in the tables and figures. From table 1 he can note such things as depth, diameter, water level, yield, use of water, temperature of water, and depth of perforations. By comparing the depth of perforations with the drillers' logs in table 3 he can note the type of material that yields water to the wells. Table 2 and figure 2 show the historic fluctuations and trends of water levels in the vicinity. From table 4 he can note the chemical quality of the water from wells in the vicinity. Table 5 shows the amount of water discharged during 1951-63 from the pumped irrigation, public supply, and industrial wells. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the state Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied.The report is also useful when planning large-scale developments of water supply. This and other uses of the report will be helped by use of the interpretive report upon its release.

Contributions of algae to GPP and DOC production in an Alaskan fen: effects of historical water table manipulations on ecosystem responses to a natural flood.

PubMed

Wyatt, Kevin H; Turetsky, Merritt R; Rober, Allison R; Giroldo, Danilo; Kane, Evan S; Stevenson, R Jan

2012-07-01

The role of algae in the metabolism of northern peatlands is largely unknown, as is how algae will respond to the rapid climate change being experienced in this region. In this study, we examined patterns in algal productivity, nutrients, and dissolved organic carbon (DOC) during an uncharacteristically wet summer in an Alaskan rich fen. Our sampling was conducted in three large-scale experimental plots where water table position had been manipulated (including both drying and wetting plots and a control) for the previous 4 years. This study allowed us to explore how much ecosystem memory of the antecedent water table manipulations governed algal responses to natural flooding. Despite no differences in water table position between the manipulated plots at the time of sampling, algal primary productivity was consistently higher in the lowered water table plot compared to the control or raised water table plots. In all plots, algal productivity peaked immediately following seasonal maxima in nutrient concentrations. We found a positive relationship between algal productivity and water-column DOC concentrations (r (2) = 0.85, P < 0.001). Using these data, we estimate that algae released approximately 19% of fixed carbon into the water column. Algal exudates were extremely labile in biodegradability assays, decreasing by more than 55% within the first 24 h of incubation. We suggest that algae can be an important component of the photosynthetic community in boreal peatlands and may become increasingly important for energy flow in a more variable climate with more intense droughts and flooding.

Integrating Residual Stress Analysis of Critical Fastener Holes into USAF Depot Maintenance

DTIC Science & Technology

2014-11-02

40 Table 15. Metrology of the initial reamer, initial hole diameters, and resulting CX for the class/type hole combinations for Pattern 1...70 Table 16. Metrology of the initial reamer, initial hole diameters, and resulting...step in the cold work process. These procedures produce a digital documentation of the hole, based on critical metrology , which can be linked with

Representing Northern Peatland Hydrology and Biogeochemistry with ALM Land Surface Model

NASA Astrophysics Data System (ADS)

Shi, X.; Ricciuto, D. M.; Thornton, P. E.; Hanson, P. J.; Xu, X.; Mao, J.; Warren, J.; Yuan, F.; Norby, R. J.; Sebestyen, S.; Griffiths, N.; Weston, D. J.; Walker, A.

2017-12-01

Northern peatlands are likely to be important in future carbon cycle-climate feedbacks due to their large carbon pool and vulnerability to hydrological change. Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. Firstly, we introduce a new configuration of the land model (ALM) of Accelerated Climate model for Energy (ACME), which includes a fully prognostic water table calculation for a vegetated peatland. Secondly, we couple our new hydrology treatment with vertically structured soil organic matter pool, and the addition of components from methane biogeochemistry. Thirdly, we introduce a new PFT for mosses and implement the water content dynamics and physiology of mosses. We inform and test our model based on SPRUCE experiment to get the reasonable results for the seasonal dynamics water table depths, water content dynamics and physiology of mosses, and correct soil carbon profiles. Then, we use our new model structure to test the how the water table depth and CH4 emission will respond to elevated CO2 and different warming scenarios.

Mobility Analyses of Standard- and High-Mobility Tactical Support Vehicles (HIMO Study)

DTIC Science & Technology

1976-02-01

l, APPENDIX G: PARTICIPANTS IN SCENARIO EXERCISES ... ....... Gl I ?S LIST OF TABLES Table Page I Summary of Vehicle Caracteristics and Some...15 1 :1010 2 :1111 Organid silts and clays ( plastic ) >7-30 0 11212 1 1 1313Peat (nou plastic ) _._>_3_0 0 .1414 Li Groups with Different Materiai in 0...diameter LL = Liquid limit PI - Plasticity index Drainage potential classified by occurrence of water table as follows: Class 0 Water table occurs at

Downwelling Far-Infrared Emission Spectra Measured By First at Cerro Toco, Chile and Table Mountain, California

NASA Astrophysics Data System (ADS)

Mast, J. C.; Mlynczak, M. G.; Cageao, R.; Kratz, D. P.; Johnson, D. G.; Mlawer, E. J.; Turner, D. D.

2014-12-01

The Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument is a Fourier transform spectrometer developed to measure the important far-infrared spectrum between 100 and 650 cm-1. Presented here are measurements made by FIRST during two successful deployments in a ground-based configuration to measure downwelling longwave radiation at Earth's surface. The initial deployment was to Cerro Toco, Chile, where FIRST operated from August to October, 2009 as part of the Radiative Heating in Underexplored Bands Campaign (RHUBC-II) campaign. After recalibration, FIRST was deployed to the Table Mountain Facility from September through October, 2012. Spectra observed at each location are substantially different, due in large part to the order of magnitude difference in integrated precipitable water vapor (0.3 cm at Table Mountain, 0.03 cm at Cerro Toco). Dry days for both campaigns are chosen for analysis - 09/24/2009 and 10/19/2012. Also available during both deployments are coincident radiosonde temperature and water vapor vertical profiles which are used as inputs a line-by-line radiative transfer program. Comparisons between measured and modeled spectra are presented over the 200 to 800 cm-1 range. An extensive error analysis of both the measured and modeled spectra is presented. In general, the differences between the measured and modeled spectra are within their combined uncertainties.

Human Health Benchmarks for Pesticides

EPA Pesticide Factsheets

Advanced testing methods now allow pesticides to be detected in water at very low levels. These small amounts of pesticides detected in drinking water or source water for drinking water do not necessarily indicate a health risk. The EPA has developed human health benchmarks for 363 pesticides to enable our partners to better determine whether the detection of a pesticide in drinking water or source waters for drinking water may indicate a potential health risk and to help them prioritize monitoring efforts.The table below includes benchmarks for acute (one-day) and chronic (lifetime) exposures for the most sensitive populations from exposure to pesticides that may be found in surface or ground water sources of drinking water. The table also includes benchmarks for 40 pesticides in drinking water that have the potential for cancer risk. The HHBP table includes pesticide active ingredients for which Health Advisories or enforceable National Primary Drinking Water Regulations (e.g., maximum contaminant levels) have not been developed.

Saline-water intrusion related to well construction in Lee County, Florida

USGS Publications Warehouse

Boggess, Durward Hoye; Missimer, T.M.; O'Donnell, T. H.

1977-01-01

Ground water is the principle source of water supply in Lee County, Florida where an estimated 30,000 wells have been drilled since 1990. These wells ranges in depth from about 10 to 1,240 feet and tap the water table aquifer or one or more of the artesian water-bearing units or zones in the Tamiami Formation, the upper part of the Hawthorn Formation, the lower part of the Hawthorn Formation and the Tampa Limestone and the Suwannee Limestone. Before 1968, nearly all wells were constructed with galvanized or black iron pipe. Many of these wells are sources of saline-water intrusion into freshwater-bearing zones. The water-bearing zones in the lower part of the Hawthorn Formation, Tampa Limestone, and Suwannee Limestone are artesian-they have higher water levels and usually contain water with a higher concentration of dissolved solids than do the aquifers occurring at shallower depths. The water from these deeper aquifers generally range in dissolved solids concentration from about 1,500 to 2,400 mg/L, and in chloride from about 500 to 1,00 mg/L. A maximum chloride concentration of 15,200 mg/L has been determined. Few of the 3,00 wells estimated to have been drilled to these zones contain sufficient casing to prevent upward flow into overlaying water-bearing zones. Because of water-level differentials, upward movement and lateral intrusion of saline water occurs principally into the upper part of the Hawthorn Formation where the chloride concentrations in water unaffected by saline-water intrusion ranges from about 80 to 150 mg/L. Where intrusion from deep artesian zones has occurred, the chloride concentration in water from the upper part of the Hawthorn Formation ranges from about 300 to more than 2,100 mg/L Surface discharges of the saline water from wells tapping the lower part of the Hawthorn Formation and the Suwannee Limestone also had affected the water-table aquifer which normally contains water with 10 to 50 mg/L of chloride. In one area, the chloride concentration in water from the water table aquifer ranged from 200 to 590 mg/L as a result of intrusion. In areas adjacent to tidal-water bodies, the water table aquifer contains water that is very saline, Where the wells in such areas have been constructed with metal casings, the metal corrodes when exposed to the saline water, and many ultimately develop holes. This permits saline water to leak into the well where the water level in the well is lower than the water table. The intrusion of saline water from the water-table aquifer into the upper part of the Hawthorn Formation is a major problem in parts of Cape Coral. Withdrawal of water from the upper part of the Hawthorn Formation has caused water levels to decline below the lowest annual position of the water table, so that downward leakage is perennial. In some coastal areas, wells that tap the upper part of the Hawthorn Formation contain water whose chloride concentration is as much as 9,500 mg/L. Upward leakage of saline water from the deep artesian aquifers and downward leakage of saline water from the water-table aquifer can be prevented by proper well construction.

Integrated watershed management in Quebec (Canada): a participatory approach centred on local solidarity.

PubMed

Baril, P; Maranda, Y; Baudrand, J

2006-01-01

The Quebec Water Policy was launched in November 2002 in support of reform of the water governance. One of the government commitments is to gradually implement watershed-based management for 33 major watercourses located primarily in the St. Lawrence plain. At the local and regional levels, watershed organizations are responsible for implementing integrated management, from a sustainable-development perspective, by preparing a master plan for water (MPW), which will include watercourses, lakes, wetlands and aquifers. These watershed organizations rely on public consultation, as well as local and regional expertise, on the responsibilities for water of the municipalities and regional county municipalities of the territory, as well as those of the ministries and other government agencies. They are also required to observe national priorities regarding protection, restoration, and development of water resources and to comply with relevant guidelines, directives, standards, regulations, and legislation. The role of watershed organizations is to act as planning and consultation tables. Government representatives are present, on the initial process, as the facilitator and for scientific and technical support. They do not have, at this moment, any voting or decisional rights. After two years, integrated water management mobilized water stakeholders on watersheds and they are on their way to initiating their first MPW.

Evaporation from bare ground with different water-table depths based on an in-situ experiment in Ordos Plateau, China

NASA Astrophysics Data System (ADS)

Zhang, Zaiyong; Wang, Wenke; Wang, Zhoufeng; Chen, Li; Gong, Chengcheng

2018-03-01

The dynamic processes of ground evaporation are complex and are related to a multitude of factors such as meteorological influences, water-table depth, and materials in the unsaturated zone. To investigate ground evaporation from a homogeneous unsaturated zone, an in-situ experiment was conducted in Ordos Plateau of China. Two water-table depths were chosen to explore the water movement in the unsaturated zone and ground evaporation. Based on the experimental and calculated results, it was revealed that (1) bare ground evaporation is an atmospheric-limited stage for the case of water-table depth being close to the capillary height; (2) the bare ground evaporation is a water-storage-limited stage for the case of water-table depth being beyond the capillary height; (3) groundwater has little effect on ground-surface evaporation when the water depth is larger than the capillary height; and (4) ground evaporation is greater at nighttime than that during the daytime; and (5) a liquid-vapor interaction zone at nearly 20 cm depth is found, in which there exists a downward vapor flux on sunny days, leading to an increasing trend of soil moisture between 09:00 to 17:00; the maximum value is reached at midday. The results of this investigation are useful to further understand the dynamic processes of ground evaporation in arid areas.

Estimating spatiotemporal variability and sustainability of shallow groundwater in a well-irrigated plain of the Haihe River basin using SWAT model

NASA Astrophysics Data System (ADS)

Zhang, Xueliang; Ren, Li; Kong, Xiangbin

2016-10-01

Quantitatively estimating the spatiotemporal variability and sustainability of shallow groundwater with a distributed hydrological model could provide an important basis for proper groundwater management, especially in well-irrigated areas. In this study, the Soil and Water Assessment Tool (SWAT) model was modified and applied to a well-irrigated plain of the Haihe River basin. First, appropriate initial values of the parameters in the groundwater module were determined based on abundant hydrogeological investigations and assessment. Then, the model was satisfactorily calibrated and validated using shallow groundwater table data from 16 national wells monitored monthly from 1993 to 2010 and 148 wells investigated yearly from 2006 to 2012. To further demonstrate the model's rationality, the multi-objective validation was conducted by comparing the simulated groundwater balance components, actual evapotranspiration, and crop yields to multiple sources data. Finally, the established SWAT was used to estimate both shallow groundwater table fluctuation and shallow aquifer water storage change in time and space. Results showed that the average shallow groundwater table declined at a rate of 0.69-1.56 m a-1, which depleted almost 350 × 108 m3 of shallow aquifer water storage in the cropland during the period of 1993-2012. Because of the heterogeneity of the underlying surface and precipitation, these variations were spatiotemporally different. Generally, the shallow groundwater table declined 1.43-1.88 m during the winter wheat (Triticum aestivum L.) growing season, while it recovered 0.28-0.57 m during the summer maize (Zea mays L.) growing season except when precipitation was exceptionally scarce. According to the simulated depletion rate, the shallow aquifer in the study area may face a depletion crisis within the next 80 years. This study identified the regions where prohibitions or restrictions on shallow groundwater exploitation should be urgently carried out.

Effects of shallow water table, salinity and frequency of irrigation water on the date palm water use

NASA Astrophysics Data System (ADS)

Askri, Brahim; Ahmed, Abdelkader T.; Abichou, Tarek; Bouhlila, Rachida

2014-05-01

In southern Tunisia oases, waterlogging, salinity, and water shortage represent serious threats to the sustainability of irrigated agriculture. Understanding the interaction between these problems and their effects on root water uptake is fundamental for suggesting possible options of improving land and water productivity. In this study, HYDRUS-1D model was used in a plot of farmland located in the Fatnassa oasis to investigate the effects of waterlogging, salinity, and water shortage on the date palm water use. The model was calibrated and validated using experimental data of sap flow density of a date palm, soil hydraulic properties, water table depth, and amount of irrigation water. The comparison between predicted and observed data for date palm transpiration rates was acceptable indicating that the model could well estimate water consumption of this tree crop. Scenario simulations were performed with different water table depths, and salinities and frequencies of irrigation water. The results show that the impacts of water table depth and irrigation frequency vary according to the season. In summer, high irrigation frequency and shallow groundwater are needed to maintain high water content and low salinity of the root-zone and therefore to increase the date palm transpiration rates. However, these factors have no significant effect in winter. The results also reveal that irrigation water salinity has no significant effect under shallow saline groundwater.

A reconnaissance study of the effect of irrigated agriculture on water quality in the Ogallala Formation, Central High Plains Aquifer

USGS Publications Warehouse

McMahon, Peter B.

2000-01-01

In 1998, the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program began a regional study of water quality in the High Plains aquifer. The High Plains aquifer underlies an area of about 174,000 square miles in parts of eight States. Because of its large size, the High Plains aquifer has been divided into three regions: the Southern High Plains, Central High Plains, and Northern High Plains. Although an assessment of water quality in each of the three regions is planned, the initial focus will be the Central High Plains aquifer. Anyone who has flown over the Central High Plains in the summer and has seen the large green circles associated with center pivot sprinklers knows that irrigated agriculture is a widespread land use. Pesticides and fertilizers applied on those irrigated fields will not degrade ground-water quality if they remain in or above the root zone. However, if those chemicals move downward through the unsaturated zone to the water table, they may degrade the quality of the ground water. Water is the principal agent for transporting chemicals from land surface to the water table, and in the semiarid Central High Plains, irrigation often represents the most abundant source of water during the growing season. One objective of NAWQA's High Plains Regional Ground-Water study is to evaluate the effect of irrigated agriculture on the quality of recently recharged water in the Ogallala Formation of the Central High Plains aquifer. The Ogallala Formation is the principal geologic unit in the Central High Plains aquifer, and it consists of poorly sorted clay, silt, sand, and gravel that generally is unconsolidated (Gutentag and others, 1984). Approximately 23 percent of the cropland overlying the Ogallala Formation is irrigated (U.S. Department of Agriculture, 1999). The NAWQA Program generally defines recently recharged ground water to be water recharged in the last 50 years. The water table in the Ogallala Formation is separated from overlying land-use practices by as much as 400 feet of unsaturated sediments. Consequently, one may hypothesize that recently recharged water is not present in the formation. The U.S. Geological Survey conducted a reconnaissance study in 1999 to establish (a) if recently recharged water was present in the Ogallala Formation underlying irrigated cropland and (b) if agricultural land-use practices affect water quality. Results from the reconnaissance study will be used to determine whether a full-scale land-use study is warranted.

Computer Simulation of Ejection Seat Performance and Preliminary Correlation with Empirical Data

DTIC Science & Technology

1980-04-01

L. . .. . 3 I r AFFDL-TR-79-31 50 TABLE OF CONTENTS SECTION PAGE I INTRODUCTION 1 1I SAFEST COMPUTER PROGRAM DESCRIPTION 8 III HITECH ...ZEARTH vs TIME 49E-I1A 53 34 ZEARTH vs XEARTH 49E-IIA 54 AFFDL-TR-79-3150 LIST OF TABLES TABLE PAGE 1 ACES II EVENT-TIME SEQUENCE 3 2 HITECH 49E-JlF...Initial Conditions 13 3 HITECH 49E-I1A Initial Conditions 14 4 HITECH Program Test Data Summary 15 5 SAFEST 49E-JIF Initial Conditions 20 6 SAFEST 49E-IIA

Hydrologic relations between lakes and aquifer in a recharge area near Orlando, Florida

USGS Publications Warehouse

Lichtler, William F.; Hughes, G.H.; Pfischner, F.L.

1976-01-01

The three lakes investigated in Orange County, Florida, gain water from adjoining water-table aquifer and lose water to Floridan aquifer by downward leakage. Net seepage (net exchange of water between lake and aquifers) can be estimated by equation S = AX + BY, where S is net seepage, X represents hydraulic gradient between lake and water-table aquifer, A is lumped parameter representing effect of hydraulic conductivity and cross-sectional area of materials in flow section of water-table aquifer, Y is head difference between lake level and potentiometric surface of Floridan aquifer, and B is lumped parameter representing effect of hydraulic conductivity, area, and thickness of materials between lake bottom and Floridan aquifer. If values of S, X, and Y are available for two contrasting water-level conditions, coefficients A and B are determinable by solution of two simultaneous equations. If the relation between lake and ground-water level is the same on all sides of the lake--with regard to each aquifer--and if X and Y are truly representative of these relations, then X and Y terms of equation provide valid estimates of inflow to lake from water-table aquifer and outflow from lake to Floridan aquifer. (Woodard-USGS)

Potential effects of sea-level rise on the depth to saturated sediments of the Sagamore and Monomoy flow lenses on Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, Donald A.; McCobb, Timothy D.; Masterson, John P.; Fienen, Michael N.

2016-05-25

In 2014, the U.S. Geological Survey, in cooperation with the Association to Preserve Cape Cod, the Cape Cod Commission, and the Massachusetts Environmental Trust, began an evaluation of the potential effects of sea-level rise on water table altitudes and depths to water on central and western Cape Cod, Massachusetts. Increases in atmospheric and oceanic temperatures arising, in part, from the release of greenhouse gases likely will result in higher sea levels globally. Increasing water table altitudes in shallow, unconfined coastal aquifer systems could adversely affect infrastructure—roads, utilities, basements, and septic systems—particularly in low-lying urbanized areas. The Sagamore and Monomoy flow lenses on Cape Cod are the largest and most populous of the six flow lenses that comprise the region’s aquifer system, the Cape Cod glacial aquifer. The potential effects of sea-level rise on water table altitude and depths to water were evaluated by use of numerical models of the region. The Sagamore and Monomoy flow lenses have a number of large surface water drainages that receive a substantial amount of groundwater discharge, 47 and 29 percent of the total, respectively. The median increase in the simulated water table altitude following a 6-foot sea-level rise across both flow lenses was 2.11 feet, or 35 percent when expressed as a percentage of the total sea-level rise. The response is nearly the same as the sea-level rise (6 feet) in some coastal areas and less than 0.1 foot near some large inland streams. Median water table responses differ substantially between the Sagamore and Monomoy flow lenses—at 29 and 49 percent, respectively—because larger surface water discharge on the Sagamore flow lens results in increased dampening of the water table response than in the Monomoy flow lens. Surface waters dampen water table altitude increases because streams are fixed-altitude boundaries that cause hydraulic gradients and streamflow to increase as sea-level rises, partially fixing the local water table altitude.The region has a generally thick vadose zone with a mean of about 38 feet; areas with depths to water of 5 feet or less, as estimated from light detection and ranging (lidar) data from 2011 and simulated water table altitudes, currently [2011] occur over about 24.9 square miles, or about 8.4 percent of the total land area of the Sagamore and Monomoy flow lenses, generally in low-lying coastal areas and inland near ponds and streams. Excluding potentially submerged areas, an additional 4.5, 9.8, and 15.9 square miles would have shallow depths to water (5 feet or less) for projected sea-level rises of 2, 4, and 6 feet above levels in 2011. The additional areas with shallow depths to water generally occur in the same areas as the areas with current [2011] depths to water of 5 feet or less: low-lying coastal areas and near inland surface water features. Additional areas with shallow depths to water for the largest sea-level rise prediction (6 feet) account for about 5.7 percent of the total land area, excluding areas likely to be inundated by seawater. The numerous surface water drainages will dampen the response of the water table to sea-level rise. This dampening, combined with the region’s thick vadose zone, likely will mitigate the potential for groundwater inundation in most areas. The potential does exist for groundwater inundation in some areas, but the effects of sea-level rise on depths to water and infrastructure likely will not be substantial on a regional level.

Predicting Stand and Stock Tables from a Spacing Study in Naturally Regenerated Longleaf Pine

Treesearch

Robert M. Farrar

1985-01-01

A prediction system is presented whereby stand and stock tables are calculated for young natural longleaf pine stands of varying initial density. Tables can be output for stand conditions of 10 to 20 years of age, 300 to 1,500 initial trees per acre (at age lo), and 70 to 80 feet in site index (index age 50). The system also allows one to translate from density...

Long-term Effects of Hydrologic Manipulations on Pore Water Dissolved Organic Carbon in an Alaskan Rich Fen

NASA Astrophysics Data System (ADS)

Rupp, D.; Kane, E. S.; Keller, J.; Turetsky, M. R.; Meingast, K. M.

2016-12-01

Boreal peatlands are experiencing rapid changes due to temperature and precipitation regime shifts in northern latitudes. In areas near Fairbanks, Alaska, thawing permafrost due to climatic changes alters peatland hydrology and thus the biogeochemical cycles within. Pore water chemistry reflects the biological and chemical processes occurring in boreal wetlands. The characterization of dissolved organic carbon (DOC) within pore water offers clues into the nature of microbially-driven biogeochemical shifts due to changing hydrology. There is mounting evidence that organic substances play an important role in oxidation-reduction (redox) reactivity of peat at northern latitudes, which is closely linked to carbon cycling. However, the redox dynamics of DOC are complex and have not been examined in depth in boreal peatlands. Here, we examine changes in organic substances and their influences on redox activity at the Alaska Peatland Experiment (APEX) site near Fairbanks, Alaska, where water table manipulation treatments have been in place since 2005 (control, raised water table, and lowered water table). With time, the altered hydrology has led to a shift in the plant community to favor sedge species in the raised water table treatment and more shrubs and non-aerenchymous plants in the lowered water table treatment. The litter from different plant functional types alters the character of the dissolved organic carbon, with more recalcitrant material containing lignin in the lowered water table plot due to the greater abundance of shrubs. A greater fraction of labile DOC in the raised treatment plot likely results from more easily decomposed sedge litter, root exudates at depth, and more frequently waterlogged conditions, which are antagonistic to aerobic microbial decomposition. We hypothesize that a greater fraction of phenolic carbon compounds supports higher redox activity. However, we note that not all "phenolic" compounds, as assayed by spectrophotometry, have the same redox activity. We report these results in the context of previous observations of higher methane fluxes from the raised water table plot. Taken together, these findings provide the mechanistic details needed to understand residual error in modeling efforts of anaerobic carbon evasion (methane and carbon dioxide) in boreal wetlands.

Water-table contours and depth to water in the southeastern part of the Sweetwater River basin, central Wyoming, 1982

USGS Publications Warehouse

Borchert, William B.

1987-01-01

This map describes the southeastern part of the Sweetwater River basin; the major aquifer consists of the upper part of the White River formations, all of Tertiary age, and to a small extent, the alluvium of the Quaternary age along the Sweetwater River. The saturated thickness of the aquifer in most of the area, but not including the alluvium ranges from 500 to 3000 ft. The maximum saturated thickness of the alluvium penetrated by test holes was 63 ft. The water-table contours and depths to water are based primarily on groundwater-level measurements made during 1982 in 104 wells, most of which are located south of the Sweetwater River. Land-surface altitudes of springs and water-surface altitudes along the Sweetwater River and perennial reaches of creeks flowing northward from the Green and Ferris Mountains also were used as control for mapping the water table. The perennial reaches shown on the map are assumed hydraulically connected with the water table. They were identified from streamflow gain-and-loss measurements made during April and May 1982. (Author 's abstract)

R-Area Reactor 1993 annual groundwater monitoring report

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

Not Available

1994-09-01

Groundwater was sampled and analyzed during 1993 from wells monitoring the following locations in R Area: Well cluster P20 east of R Area (one well each in the water table and the McBean formation), the R-Area Acid/Caustic Basin (the four water-table wells of the RAC series), the R-Area Ash Basin/Coal Pile (one well of the RCP series in the Congaree formation and one in the water table), the R-Area Disassembly Basin (the three water-table wells of the RDB series), the R-Area Burning/Rubble Pits (the four water-table wells of the RRP series), and the R-Area Seepage Basins (numerous water-table wells inmore » the RSA, RSB, RSC, RSD, RSE, and RSF series). Lead was the only constituent detected above its 50{mu}g/L standard in any but the seepage basin wells; it exceeded that level in one B well and in 23 of the seepage basin wells. Cadmium exceeded its drinking water standard (DWS) in 30 of the seepage basin wells, as did mercury in 10. Nitrate-nitrite was above DWS once each in two seepage basin wells. Tritium was above DWS in six seepage basin wells, as was gross alpha activity in 22. Nonvolatile beta exceeded its screening standard in 29 wells. Extensive radionuclide analyses were requested during 1993 for the RCP series and most of the seepage basin wells. Strontium-90 in eight wells was the only specific radionuclide other than tritium detected above DWS; it appeared about one-half of the nonvolatile beta activity in those wells.« less

Channel Incision Driven by Suburbanization: Impacts to Riparian Groundwater Flow and Overbank Flow Frequency

NASA Astrophysics Data System (ADS)

Bowles, C. J.; Lawrence, R. L.; Noll, C.; Hancock, G. S.

2005-12-01

Channel incision is a widely observed response to increased flow in urbanized watersheds, but the effects of channel lowering on riparian water tables is not well documented. In a rapidly incising suburban stream in the Virginia Coastal Plain, we hypothesize that stream incision has lowered floodplain water tables and decreased the overbank flow frequency. The monitored stream is a tributary to the James River draining 1.3 km2 of which 15% is impervious cover. Incision has occurred largely through upstream migration of a one meter high knickpoint at a rate of ~1.5 m/yr, primarily during high flow events. We installed 63 wells in six stream-perpendicular transects as well as a cluster of wells around the knickpoint to assess water table elevations beneath the floodplain adjacent to the incising stream. Two transects are located 30 and 50 m upstream of the knickpoint in the unincised floodplain, and the remainder are 5, 30, 70, and 100 m downstream in the incised floodplain. In one transect above and two below, pressure transducers attached to dataloggers provide a high-resolution record of water table changes. Erosion pins were installed and channel cross-sections surveyed to determine streambed stability. Significant differences are observed in bank morphology and groundwater flow above vs. below the knickpoint. Above the knickpoint, the banks are stable, ~3 m wide, and ~0.3 m deep, and widen and deepen slightly toward the knickpoint. The water table is relatively flat and is 0.2-0.4 m below the floodplain surface, and groundwater contours suggest flow is parallel to the stream direction. The water table responds immediately to precipitation events, and rises to the floodplain surface in significant rainfall events. Immediately downstream of the knickpoint, channel width increases by about a meter, and stream depth increases to ~1.5 meters. The water table immediately below the knickpoint possesses a steep gradient, and is up to one meter below the floodplain surface. Groundwater flow is redirected toward the stream. Moving downstream banks continue to widen, and the channel is up to 8 m wide and ~1.3 m deep ~100 m below the current knickpoint position. In the most downstream transects, the water table slopes gently toward the stream and remains ~1 m below the floodplain surface, equivalent to the depth of incision generated by knickpoint passage. Upstream of the knickpoint, overbank flooding occurs frequently, while below the knickpoint the majority of storm flow is contained within the incised channel and occupation of the floodplain is rare. The impact of incision to the riparian water table is dramatic, with a lowered water table and redirection of groundwater flow toward the stream. The incision is driven by suburbanization upstream of this riparian corridor, and has likely reduced the ability of this protected riparian system to improve the water quality of the suburban runoff that passes through it.

Optimal designs of bioretention cells in shallow groundwater

NASA Astrophysics Data System (ADS)

Zhang, K.; Chui, T. F. M.

2017-12-01

Bioretention cells, as one representative low impact development practices, have been proved to be effective in controlling surface runoff, removing pollutants and recharging groundwater. However, they are often not recommended in shallow groundwater areas due to potential groundwater pollution, reduction in runoff control performance and groundwater drainage through the underdrain. Most design guidelines only require a minimum distance between bioretention cell bottom and seasonal high groundwater table without guiding the design of bioretention cells to mitigate the problem of shallow groundwater. This study therefore proposed some design recommendations of bioretention cells for different rainfall runoff loads, native soil types and initial water table depths. A variably saturated flow model was employed to conduct event-based simulations on one single hypothetical bioretention cell in shallow groundwater, which was calibrated using experimental and simulation data of an on-site bioretention cell. A wide range of climatic and geophysical factors (i.e. initial groundwater depths, native soils, rainfall runoff loads) and bioretention designs (i.e. media soil types and underdrain sizes) were considered. Surface runoff reduction, time before groundwater mound formation, as well as maximum height of groundwater mound were evaluated. Less-permeable media types (i.e. sandy loam) are recommended in areas with many extreme rainfall events (i.e. 40 - 70 mm/h or larger) and of shallower groundwater, which can better protect groundwater from mounding and possibly contamination although may slightly compromise the runoff control performance. For areas having seasonal high groundwater table of 0 - 1 m below bioretention bottom, underdrain is recommended to maintain good infiltration capacity without draining groundwater. However, underdrain is not recommended for areas of groundwater table always near or above the bioretention bottom, only if an impermeable sheet is added. Generally, groundwater interference is a concern only when groundwater table is above 1 - 2.5 m below bioretention bottom and runoff loads are very high. The results of this study overall could benefit the implementation of bioretention cells in shallow groundwater areas, and the establishment of relevant design guidelines.

3. DETAIL OF STONEWORK ON ARCH, WATER TABLE AND DENTILS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. DETAIL OF STONEWORK ON ARCH, WATER TABLE AND DENTILS ON EAST ELEVATION LOOKING NORTHWEST. - Original Airport Entrance Overpass, Spanning original Airport Entrance Road at National Airport, Arlington, Arlington County, VA

Wetland tree transpiration modified by river-floodplain connectivity

USGS Publications Warehouse

Allen, Scott T.; Krauss, Ken W.; Cochran, J. Wesley; King, Sammy L.; Keim, Richard F.

2016-01-01

Hydrologic connectivity provisions water and nutrient subsidies to floodplain wetlands and may be particularly important in floodplains with seasonal water deficits through its effects on soil moisture. In this study, we measured sapflow in 26 trees of two dominant floodplain forest species (Celtis laevigata and Quercus lyrata) at two hydrologically distinct sites in the lower White River floodplain in Arkansas, USA. Our objective was to investigate how connectivity-driven water table variations affected water use, an indicator of tree function. Meteorological variables (photosynthetically active radiation and vapor pressure deficit) were the dominant controls over water use at both sites; however, water table variations explained some site differences. At the wetter site, highest sapflow rates were during a late-season overbank flooding event, and no flood stress was apparent. At the drier site, sapflow decreased as the water table receded. The late-season flood pulse that resulted in flooding at the wetter site did not affect the water table at the drier site; accordingly, higher water use was not observed at the drier site. The species generally associated with wetter conditions (Q. lyrata) was more positively responsive to the flood pulse. Flood water subsidy lengthened the effective growing season, demonstrating ecological implications of hydrologic connectivity for alleviating water deficits that otherwise reduce function in this humid floodplain wetland.

HCMM energy budget data as a model input for assessing regions of high potential ground-water pollution

NASA Technical Reports Server (NTRS)

Moore, D. G. (Principal Investigator); Heilman, J.; Tunheim, J.

1978-01-01

The author has identified the following significant results. Analysis of soil temperature and water table data indicated that shallow aquifers appear to produce a heat sink effect when the depth to water table is approximately four meters or less.

Investigating local variation in groundwater recharge along a topographic gradient, Walnut Creek, Iowa, USA

USGS Publications Warehouse

Schilling, K.E.

2009-01-01

Groundwater recharge is an important component to hydrologic studies but is known to vary considerably across the landscape. The purpose of this study was to examine 4 years of water-level behavior in a transect of four water-table wells installed at Walnut Creek, Iowa, USA to evaluate how groundwater recharge varied along a topographic gradient. The amount of daily water-table rise (WTR) in the wells was summed at monthly and annual scales and estimates of specific yield (Sy) were used to convert the WTR to recharge. At the floodplain site, Sy was estimated from the ratio of WTR to total rainfall and in the uplands was based on the ratio of baseflow to WTR. In the floodplain, where the water table is shallow, recharge occurred throughout the year whenever precipitation occurred. In upland areas where the water table was deeper, WTR occurred in a stepped fashion and varied by season. Results indicated that the greatest amount of water-table rise over the 4-year period was observed in the floodplain (379 mm), followed by the upland (211 mm) and sideslopes (122 mm). Incorporating spatial variability in recharge in a watershed will improve groundwater resource evaluation and flow and transport modeling. ?? Springer-Verlag 2008.

Predcition of Long term Water table Trends in Response to Groundwater Irrigation and Climate Change in an Indian Context

NASA Astrophysics Data System (ADS)

Thekkemeppilly Sivakumar, I.; Steenhuis, T. S.; Walter, M. F.; Ghosh, S.; Salvi, K. A.

2015-12-01

Intensified groundwater irrigation is a major factor that contributes to water table decline. This phenomenon has been documented in many parts of the world. This study investigates trends in water table in response to agriculture intensification to meet increasing food demand, water management practices and climate change. A shallow-aquifer model based on the extended Thornthwaite-Mather procedure is used to predict groundwater levels in response to precipitation, evapotranspiration, and groundwater pumping for irrigation. Krishna district in the state of Andhra Pradesh in southern India which has a sub-humid, monsoon climate and Calicut district of Kerala state with a wet tropical monsoon climate have been chosen as sites for this study. The effect of increasing food demand by a growing population is investigated by increasing the number of crops per year from one to three. We consider three climate scenarios and two water management practices in this study. The three climate scenarios are the ones those envisaged by the Intergovernmental Panel for Climate Change (IPCC). The two water management practices considered are the traditional flooded agriculture and the system of rice intensification method which does not use total flooding. The results show that single crop agriculture in Krishna district is sustainable for all climate scenarios and water management practices with a maximum depth to water table around 6 - 7 m at the end of dry season and the water table recovers to the surface most of the time. Increasing crop production with two or three crops per year with groundwater irrigation is unsustainable with the water table levels dropping potentially to 200 - 1000 m at the end of 21st century. We found that climate change and better irrigation water management practices affected ground water levels only minimally compared to the growing more than one crop per year. Our study leads to the conclusion that ground water irrigated rice can only be sustainable when crop evaporation is less then precipitation and in order to meet increasing food demands the rice yield per unit water should be improved.

Estimation of water table based on geomorphologic and geologic conditions using public database of geotechnical information over Japan

NASA Astrophysics Data System (ADS)

Koshigai, Masaru; Marui, Atsunao

Water table provides important information for the evaluation of groundwater resource. Recently, the estimation of water table in wide area is required for effective evaluation of groundwater resources. However, evaluation process is met with difficulties due to technical and economic constraints. Regression analysis for the prediction of groundwater levels based on geomorphologic and geologic conditions is considered as a reliable tool for the estimation of water table of wide area. Data of groundwater levels were extracted from the public database of geotechnical information. It was observed that changes in groundwater level depend on climate conditions. It was also observed and confirmed that there exist variations of groundwater levels according to geomorphologic and geologic conditions. The objective variable of the regression analysis was groundwater level. And the explanatory variables were elevation and the dummy variable consisting of group number. The constructed regression formula was significant according to the determination coefficients and analysis of the variance. Therefore, combining the regression formula and mesh map, the statistical method to estimate the water table based on geomorphologic and geologic condition for the whole country could be established.

Modeling the effects of hydrology on gross primary productivity and net ecosystem productivity at Mer Bleue bog

NASA Astrophysics Data System (ADS)

Dimitrov, Dimitre D.; Grant, Robert F.; Lafleur, Peter M.; Humphreys, Elyn R.

2011-12-01

The ecosys model was applied to investigate the effects of water table and subsurface hydrology changes on carbon dioxide exchange at the ombrotrophic Mer Bleue peatland, Ontario, Canada. It was hypothesized that (1) water table drawdown would not affect vascular canopy water potential, hence vascular productivity, because roots would penetrate deeper to compensate for near-surface dryness, (2) moss canopy water potential and productivity would be severely reduced because rhizoids occupy the uppermost peat that is subject to desiccation with water table decline, and (3) given that in a previous study of Mer Bleue, ecosystem respiration showed little sensitivity to water table drawdown, gross primary productivity would mainly determine the net ecosystem productivity through these vegetation-subsurface hydrology linkages. Model output was compared with literature reports and hourly eddy-covariance measurements during 2000-2004. Our findings suggest that late-summer water table drawdown in 2001 had only a minor impact on vascular canopy water potential but greatly impacted hummock moss water potential, where midday values declined to -250 MPa on average in the model. As a result, simulated moss productivity was reduced by half, which largely explained a reduction of 2-3 μmol CO2 m-2 s-1 in midday simulated and measurement-derived gross primary productivity and an equivalent reduction in simulated and measured net ecosystem productivity. The water content of the near-surface peat (top 5-10 cm) was found to be the most important driver of interannual variability of annual net ecosystem productivity through its effects on hummock moss productivity and on ecosystem respiration.

Effect of sequential release of NAPLs on NAPL migration in porous media

NASA Astrophysics Data System (ADS)

Bang, Woohui; Yeo, In Wook

2016-04-01

NAPLs (Non-aqueous phase liquids) are common groundwater contaminants and are classified as LNAPLs (Light non-aqueous phase liquids) and DNAPLs (Dense non-aqueous phase liquids) according to relative density for water. Due to their low solubility in water, NAPLs remain for a long time in groundwater, and they pose a serious environmental problem. Therefore, understanding NAPLs migration in porous media is essential for effective NAPLs remediation. DNAPLs tend to move downward through the water table by gravity force because its density is higher than water. However, if DNAPLs do not have sufficient energy which breaks capillary force of porous media, they will just accumulate above capillary zone or water table. Mobile phase of LNAPLs rises and falls depending on fluctuation of water table, and it could change the wettability of porous media from hydrophilic to hydrophobic. This could impacts on the migration characteristics of subsequently-released DNAPLs. LNAPLs and DNAPLs are sometime disposed at the same place (for example, the Hill air force base, USA). Therefore, this study focuses on the effect of sequential release of NAPLs on NAPLs (in particular, DNAPL) migration in porous media. We have conducted laboratory experiments. Gasoline, which is known to change wettability of porous media from hydrophilic to intermediate, and TCE (Trichloroethylene) were used as LNAPL and DNAPL, respectively. Glass beads with the grain size of 1 mm and 2 mm were prepared for two sets of porous media. Gasoline and TCE was dyed for visualization. First, respective LNAPL and DNAPL of 10 ml were separately released into prepared porous media. For the grain size of 2 mm glass beads, LNAPL became buoyant above the water table, and DNAPL just moved downward through porous media. However, for the experiment with the grain size of 1 mm glass beads, NAPLs behaved very differently. DNAPL did not migrate downward below and just remained above the water table due to capillary pressure of porous media. To study the effect of subsequent release of NAPLs, as soon as LNAPL was released to porous medium with 1 mm of glass beads, being buoyant above water table, water table was lowered, which left residuals along the path of LNAPL. DNAPL was subsequently released. DNAPL was breaking through the water table now, which was opposed to only DNAPL release case. This study indicates that sequential release of NAPLs can leads to different migration characteristics of NAPLs, compared with the release of single phase NAPL into porous media.

Spring sapping origin of the enigmatic relict valleys of Cape Cod and Martha's Vineyard and Nantucket Islands, Massachusetts

USGS Publications Warehouse

Uchupi, E.; Oldale, R.N.

1994-01-01

Steep-sided, flat-floored linear valleys that lack well developed tributaries and end in amphitheater-like heads are eroded on the outwash plains of Cape Cod, Martha's Vineyard and Nantucket Island. The valleys are restricted from the mid to the distal ends of the outwash plains and show no connection to possible water sources at the updip end of the plains. Their distribution and morphology lead us to propose that they were eroded by groundwater seeps fed by proglacial lakes (the high hydrostatic heads of the lakes led to the elevation of the water table) dammed by the outwash plains and associated moraines. The valleys on Cape Cod were initiated by seeps along the foreset surfaces of sandy deltas emplaced in lakes in Nantucket Sound and Cape Cod Bay after these lakes drained. Those on Martha's Vineyard and Nantucket islands were either eroded by seeps at the distal ends of outwash plain wedges emplaced atop the subareal continental shelf south of the islands or along the foreset surfaces of sandy deltas emplaced on a lake behind a peripheral crustal bulge south of the glacial front. Valley erosion terminated after the lakes were drained and the water table dropped. ?? 1994.

Holes in the Bathtub: Water Table Dependent Services and Threshold Behavior in an Economic Model of Groundwater Extraction

NASA Astrophysics Data System (ADS)

Kirk-lawlor, N. E.; Edwards, E. C.

2012-12-01

In many groundwater systems, the height of the water table must be above certain thresholds for some types of surface flow to exist. Examples of flows that depend on water table elevation include groundwater baseflow to river systems, groundwater flow to wetland systems, and flow to springs. Meeting many of the goals of sustainable water resource management requires maintaining these flows at certain rates. Water resource management decisions invariably involve weighing tradeoffs between different possible usage regimes and the economic consequences of potential management choices are an important factor in these tradeoffs. Policies based on sustainability may have a social cost from forgoing present income. This loss of income may be worth bearing, but should be well understood and carefully considered. Traditionally, the economic theory of groundwater exploitation has relied on the assumption of a single-cell or "bathtub" aquifer model, which offers a simple means to examine complex interactions between water user and hydrologic system behavior. However, such a model assumes a closed system and does not allow for the simulation of groundwater outflows that depend on water table elevation (e.g. baseflow, springs, wetlands), even though those outflows have value. We modify the traditional single-cell aquifer model by allowing for outflows when the water table is above certain threshold elevations. These thresholds behave similarly to holes in a bathtub, where the outflow is a positive function of the height of the water table above the threshold and the outflow is lost when the water table drops below the threshold. We find important economic consequences to this representation of the groundwater system. The economic value of services provided by threshold-dependent outflows (including non-market value), such as ecosystem services, can be incorporated. The value of services provided by these flows may warrant maintaining the water table at higher levels than would be the case if only the benefits and costs of groundwater extraction were considered. This hole-in-the-bathtub model can motivate managers to consider the costs of the loss of such flows, which may be very costly (in terms of loss of environmental services, loss of access to surface water, etc.). Alternatively, the decision to maintain the water table at an elevation that sustains a threshold-dependent outflow may cause income loss from the imposition of lower groundwater extraction rates. Weighing the benefits of maintaining threshold-dependent flows (including non-market benefits) with the net benefits of increased extraction is an important step in a prudent water management framework. To illustrate the usefulness of the modified model in a joint economic-hydrologic context, we provide a short case study of the Ojos de San Pedro area of the Rio Loa Basin in northern Chile. Evidence indicates that a wetland and lacustrine environment and a village dependent on that environment disappeared due to water extraction for industrial use. We demonstrate how the key features of the model provide important insight in understanding the tradeoffs that were made in this case.

A 5 Year Study of Carbon Fluxes from a Restored English Blanket Bog

NASA Astrophysics Data System (ADS)

Worrall, F.; Dixon, S.; Evans, M.

2014-12-01

This study aimed to measure the effects of ecological restoration on blanket peat water table depths, DOC concentrations and CO2 fluxes. In April 2003 the Bleaklow Plateau, an extensive area of deep blanket peat in the Peak District National Park, northern England, was devegetated by a wildfire. As a result the area was selected for large scale restoration. In this study we considered a 5-year study of four restored sites in comparison to both an unrestored, bare peat control and to vegetated control that did not require restoration. Results suggested that sites with revegetation alongside slope stabilisation had the highest rates of photosynthesis and were the largest net (daylight hours) sinks of CO2. Bare sites were the largest net sources of CO2 and had the deepest water table depths. Sites with gully wall stabilisation were between 5-8 times more likely to be net CO2 sinks than the bare sites. Revegetation without gully flow blocking using plastic dams did not have a large effect on water table depths in and around the gullies investigated whereas a blocked gully had water table depths comparable to a naturally revegetating gully. A ten centimetre lowering in water table depth decreased the probability of observing a net CO2 sink, on a given site, by up to 30%. With respect to DOC the study showed that the average soil porewater DOC concentration on the restored sites rose significantly over the 5 year study representing a 34% increase relative to the vegetated control and an 11% increase relative to the unrestored, bare control. Soil pore water concentrations were not significantly different from surface runoff DOC concentrations and therefore restoration as conducted by this study would have contributed to water quality deterioration in the catchment. The most important conclusion of this research was that restoration interventions were apparently effective at increasing the likelihood of net CO2 sink behaviour and raising water tables on degraded, climatically marginal blanket bog. However, had water table restoration been conducted alongside revegetation then a significant decline in DOC concentrations could have also been realised.

The role of hydrological initial conditions on Atmospheric River floods in the Russian River basin

NASA Astrophysics Data System (ADS)

Cao, Q.; Mehran, A.; Ralph, M.; Cannon, F.; Lettenmaier, D. P.

2017-12-01

A body of work over the last decade or so has demonstrated that most major floods along the U.S. West Coast are attributable to Atmospheric Rivers (ARs). Antecedent hydrological conditions play an important part in the natural links between precipitation and floods, and this is especially the case in the Pacific Coastal region where precipitation is strongly winter-dominant, and many potentially flood-inducing events occur relatively early in the wet season. The Russian River Basin has these characteristics, the result of which is mostly dry soils at the onset of the fall precipitation season. There is therefore a tradeoff in terms of flood potential between the strength of AR events, and the time history of previous precipitation that has begun to wet soils and raise local water tables. In order to examine flood responses associated with varying precursor hydrological conditions, we first constructed a data set of AR events that were coincident with Peaks Over Threshold (POT) extreme discharge events at selected USGS stream gauges throughout the Russian River basin. We investigated the role of antecedent soil moisture and water table conditions on historical AR flooding, initially using an exploratory data analysis approach. We then implemented the Distributed Hydrology-Soil-Vegetation Model (DHSVM) over the entire basin and conducted modeling experiments for each of the POT events under climatological and extreme antecedent conditions. We reconstructed climatological soil moisture by assimilating in situ observations into long-term soil moisture simulations from the UCLA Western U.S. Drought Monitoring System. We explore an envelope of frequency distributions of floods given a range of AR-related extreme precipitation and various initial hydrologic conditions, which eventually should have implications for flood management decision-making.

Specific conductance and water temperature data for San Francisco Bay, California, for Water Year 2004

USGS Publications Warehouse

Buchanan, P.A.

2005-01-01

This article presents time-series graphs of specificconductance and water-temperature data collected in San Francisco Bay during water year 2004 (October 1, 2003, through September 30, 2004). Specific-conductance and water-temperature data were recorded at 15-minute intervals at seven U.S. Geological Survey (USGS) locations (Figure 1, Table 1). Specific-conductance and water-temperature data from Point San Pablo (PSP) and San Mateo Bridge (SMB) were recorded by the California Department of Water Resources (DWR) before 1988, by the USGS National Research Program from 1988 to 1989, and by the USGSDWR cooperative program since 1990. Benicia Bridge (BEN), Carquinez Bridge (CARQ), and Napa River (NAP) were established in 1998 by the USGS. San Pablo Bay (SPB) was initially established in 1998 at Channel Marker 9 but was moved to Channel Marker 1 in 2003. The monitoring station at Alcatraz (ALC) was established in 2003 by the USGS to replace the discontinued monitoring station San Francisco Bay at Presidio Military Reservation.

Geoarchaeological and paleohydrological evidence for a clovis-age drought in North America and its bearing on extinction

NASA Astrophysics Data System (ADS)

Haynes, C. Vance

1991-05-01

At the Murray Springs Clovis site in southeastern Arizona, stratigraphic and geomorphic evidence indicates that an abnormally low water table 10,900 yr B.P. was followed soon thereafter by a water-table rise accompanied by the deposition of an algal mat (the black mat) that buried mammoth tracks, Clovis artifacts, and a well. This water-table fluctuation correlates with pluvial lake fluctuations in the Great Basin during and immediately following Clovis occupation of that region. Many elements of Pleistocene megafauna in North America became extinct during the dry period. Oxygen isotope records show a marked decrease in δ18O correlated with the Younger Dryas cold-dry event of northern Europe which ended 10,750 yr B.P., essentially the same time as the water table began to rise in southeastern Arizona. Clovis hunters may have found large game animals easier prey when concentrated at water holes and under stress. If so, both climate and human predation contributed to Pleistocene extinction in America.

TU-CD-304-01: FEATURED PRESENTATION and BEST IN PHYSICS (THERAPY): Trajectory Modulated Arc Therapy: Development of Novel Arc Delivery Techniques Integrating Dynamic Table Motion for Extended Volume Treatments

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

Chin, E; Hoppe, R; Million, L

2015-06-15

Purpose: Integration of coordinated robotic table motion with inversely-planned arc delivery has the potential to resolve table-top delivery limitations of large-field treatments such as Total Body Irradiation (TBI), Total Lymphoid Irradiation (TLI), and Cranial-Spinal Irradiation (CSI). We formulate the foundation for Trajectory Modulated Arc Therapy (TMAT), and using Varian Developer Mode capabilities, experimentally investigate its practical implementation for such techniques. Methods: A MATLAB algorithm was developed for inverse planning optimization of the table motion, MLC positions, and gantry motion under extended-SSD geometry. To maximize the effective field size, delivery trajectories for TMAT TBI were formed with the table rotated atmore » 270° IEC and dropped vertically to 152.5cm SSD. Preliminary testing of algorithm parameters was done through retrospective planning analysis. Robotic delivery was programmed using custom XML scripting on the TrueBeam Developer Mode platform. Final dose was calculated using the Eclipse AAA algorithm. Initial verification of delivery accuracy was measured using OSLDs on a solid water phantom of varying thickness. Results: A comparison of DVH curves demonstrated that dynamic couch motion irradiation was sufficiently approximated by static control points spaced in intervals of less than 2cm. Optimized MLC motion decreased the average lung dose to 68.5% of the prescription dose. The programmed irradiation integrating coordinated table motion was deliverable on a TrueBeam STx linac in 6.7 min. With the couch translating under an open 10cmx20cm field angled at 10°, OSLD measurements along the midline of a solid water phantom at depths of 3, 5, and 9cm were within 3% of the TPS AAA algorithm with an average deviation of 1.2%. Conclusion: A treatment planning and delivery system for Trajectory Modulated Arc Therapy of extended volumes has been established and experimentally demonstrated for TBI. Extension to other treatment techniques such as TLI and CSI is readily achievable through the developed platform. Grant Funding by Varian Medical Systems.« less

Groundwater flow, heat transport, and water table position within volcanic edifices: Implications for volcanic processes in the Cascade Range

USGS Publications Warehouse

Hurwitz, S.; Kipp, K.L.; Ingebritsen, S.E.; Reid, M.E.

2003-01-01

The position of the water table within a volcanic edifice has significant implications for volcano hazards, geothermal energy, and epithermal mineralization. We have modified the HYDROTHERM numerical simulator to allow for a free-surface (water table) upper boundary condition and a wide range of recharge rates, heat input rates, and thermodynamic conditions representative of continental volcano-hydrothermal systems. An extensive set of simulations was performed on a hypothetical stratovolcano system with unconfined groundwater flow. Simulation results suggest that the permeability structure of the volcanic edifice and underlying material is the dominant control on water table elevation and the distribution of pressures, temperatures, and fluid phases at depth. When permeabilities are isotropic, water table elevation decreases with increasing heat flux and increases with increasing recharge, but when permeabilities are anisotropic, these effects can be much less pronounced. Several conditions facilitate the ascent of a hydrothermal plume into a volcanic edifice: a sufficient source of heat and magmatic volatiles at depth, strong buoyancy forces, and a relatively weak topography-driven flow system. Further, the plume must be connected to a deep heat source through a pathway with a time-averaged effective permeability ???1 ?? 10-16 m2, which may be maintained by frequent seismicity. Topography-driven flow may be retarded by low permeability in the edifice and/or the lack of precipitation recharge; in the latter case, the water table may be relatively deep. Simulation results were compared with observations from the Quaternary stratovolcanoes along the Cascade Range of the western United States to infer hydrothermal processes within the edifices. Extensive ice caps on many Cascade Range stratovolcanoes may restrict recharge on the summits and uppermost flanks. Both the simulation results and limited observational data allow for the possibility that the water table beneath the stratovolcanoes is relatively deep.

Water Table and Soil Gas Emission Responses to Disturbance in Northern Forested Wetlands

NASA Astrophysics Data System (ADS)

Pypker, T. G.; Van Grinsven, M. J.; Bolton, N. W.; Shannon, J.; Davis, J.; Wagenbrenner, J. W.; Sebestyen, S. D.; Kolka, R. K.

2014-12-01

Exotic pest infestations are increasingly common throughout North American forests. In forested wetlands, disturbance events may alter nutrient, carbon, and hydrologic pathways. Recently, ash (Fraxinus spp.) forests in North Central and Eastern North America have been exposed to the exotic emerald ash borer (EAB) (Burprestidae: Agrilus planipennis), and the rapid and extensive expansion of EAB populations since 2001 may soon eliminate most existing ash stands. Limited research has focused on post-establishment ecosystem impacts of an EAB disturbance, and to our knowledge, there are no studies that have evaluated the coupled response of black ash (Fraxinus nigra) wetland water tables, soil temperatures, and soil gas emissions to an EAB infestation. We present preliminary results that detail those responses to a simulated EAB disturbance. Water table position, soil temperature, and soil gas emissions (CO2 and CH4) were monitored in nine black ash wetlands in the Upper Peninsula of Michigan for three years, including one year of pre-treatment and two years of post-treatment data-collection. An EAB disturbance was simulated by girdling (Girdle) or felling (Clearcut) all black ash trees with diameters of 2.5 cm or greater within the wetland, and each treatment was applied to three sites. The results indicate that wetland water tables were insensitive to treatment effects, soil temperatures were significantly higher in the Clearcut treatment, soil gas flux was significantly higher in the Clearcut treatment, and the rate of soil gas flux was strongly regulated by water table position and temperature. No significant treatment effects were detected in the Girdle treatment during the first post-treatment year. Because water tables were insensitive to treatment, we concluded that water tables did not independently generate a soil gas flux response despite their strong regulatory influence. Furthermore, we concluded that the response of soil temperature to disturbance was largely the reason why elevated soil gas flux rates were observed in the Clearcut treatment.

An enhanced model of land water and energy for global hydrologic and earth-system studies

USGS Publications Warehouse

Milly, Paul C.D.; Malyshev, Sergey L.; Shevliakova, Elena; Dunne, Krista A.; Findell, Kirsten L.; Gleeson, Tom; Liang, Zhi; Phillips, Peter; Stouffer, Ronald J.; Swenson, Sean

2014-01-01

LM3 is a new model of terrestrial water, energy, and carbon, intended for use in global hydrologic analyses and as a component of earth-system and physical-climate models. It is designed to improve upon the performance and to extend the scope of the predecessor Land Dynamics (LaD) and LM3V models by better quantifying the physical controls of climate and biogeochemistry and by relating more directly to components of the global water system that touch human concerns. LM3 includes multilayer representations of temperature, liquid water content, and ice content of both snowpack and macroporous soil–bedrock; topography-based description of saturated area and groundwater discharge; and transport of runoff to the ocean via a global river and lake network. Sensible heat transport by water mass is accounted throughout for a complete energy balance. Carbon and vegetation dynamics and biophysics are represented as in LM3V. In numerical experiments, LM3 avoids some of the limitations of the LaD model and provides qualitatively (though not always quantitatively) reasonable estimates, from a global perspective, of observed spatial and/or temporal variations of vegetation density, albedo, streamflow, water-table depth, permafrost, and lake levels. Amplitude and phase of annual cycle of total water storage are simulated well. Realism of modeled lake levels varies widely. The water table tends to be consistently too shallow in humid regions. Biophysical properties have an artificial stepwise spatial structure, and equilibrium vegetation is sensitive to initial conditions. Explicit resolution of thick (>100 m) unsaturated zones and permafrost is possible, but only at the cost of long (≫300 yr) model spinup times.

Methods to predict seasonal high water table (SHGWT) : final report.

DOT National Transportation Integrated Search

2017-04-03

The research study was sectioned into 5 separate tasks. Task 1 included defining the seasonal high ground water table (SHGWT); describing : methods and techniques used to determine SHGWTs; identify problems associated with estimating SHGWT conditions...

Thermal and hydrological observations near Twelvemile Lake in discontinuous permafrost, Yukon Flats, interior Alaska, September 2010-August 2011

USGS Publications Warehouse

Jepsen, Steven M.; Koch, Joshua C.; Rose, Joshua R.; Voss, Clifford I.; Walvoord, Michelle Ann

2012-01-01

A series of ground-based observations were made between September 2010 and August 2011 near Twelvemile Lake, 19 kilometers southwest of Fort Yukon, Alaska, for use in ongoing hydrological analyses of watersheds in this region of discontinuous permafrost. Measurements include depth to ground ice, depth to water table, soil texture, soil moisture, soil temperature, and water pressure above the permafrost table. In the drained basin of subsiding Twelvemile Lake, we generally find an absence of newly formed permafrost and an undetectable slope of the water table; however, a sloping water table was observed in the low-lying channels extending into and away from the lake watershed. Datasets for these observations are summarized in this report and can be accessed by clicking on the links in each section or from the Downloads folder of the report Web page.

Flow in a discrete slotted nozzle with massive injection. [water table tests

NASA Technical Reports Server (NTRS)

Perkins, H. C.

1974-01-01

An experimental investigation has been conducted to determine the effect of massive wall injection on the flow characteristics in a slotted nozzle. Some of the experiments were performed on a water table with a slotted-nozzle test section. This has 45 deg and 15 deg half angles of convergence and divergence, respectively, throat radius of 2.5 inches, and throat width of 3 inches. The hydraulic analogy was employed to qualitatively extend the results to a compressible gas flow through the nozzle. Experimental results from the water table include contours of constant Froude and Mach number with and without injection. Photographic results are also presented for the injection through slots of CO2 and Freon-12 into a main-stream air flow in a convergent-divergent nozzle in a wind tunnel. Schlieren photographs were used to visualize the flow, and qualititative agreement between the results from the gas tunnel and water table is good.

75 FR 44767 - Folding Metal Tables and Chairs From the People's Republic of China: Initiation of New Shipper...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-29

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-868] Folding Metal Tables and... review of the antidumping duty order on folding metal tables and chairs (``FMTCs'') from the People's... on June 27, 2002. See Antidumping Duty Order: Folding Metal Tables and Chairs From the People's...

Modeling Subsurface Hydrology in Floodplains

NASA Astrophysics Data System (ADS)

Evans, Cristina M.; Dritschel, David G.; Singer, Michael B.

2018-03-01

Soil-moisture patterns in floodplains are highly dynamic, owing to the complex relationships between soil properties, climatic conditions at the surface, and the position of the water table. Given this complexity, along with climate change scenarios in many regions, there is a need for a model to investigate the implications of different conditions on water availability to riparian vegetation. We present a model, HaughFlow, which is able to predict coupled water movement in the vadose and phreatic zones of hydraulically connected floodplains. Model output was calibrated and evaluated at six sites in Australia to identify key patterns in subsurface hydrology. This study identifies the importance of the capillary fringe in vadose zone hydrology due to its water storage capacity and creation of conductive pathways. Following peaks in water table elevation, water can be stored in the capillary fringe for up to months (depending on the soil properties). This water can provide a critical resource for vegetation that is unable to access the water table. When water table peaks coincide with heavy rainfall events, the capillary fringe can support saturation of the entire soil profile. HaughFlow is used to investigate the water availability to riparian vegetation, producing daily output of water content in the soil over decadal time periods within different depth ranges. These outputs can be summarized to support scientific investigations of plant-water relations, as well as in management applications.

Relationships between water table and model simulated ET

Treesearch

Prem B. Parajuli; Gretchen F. Sassenrath; Ying Ouyang

2013-01-01

This research was conducted to develop relationships among evapotranspiration (ET), percolation (PERC), groundwater discharge to the stream (GWQ), and water table fluctuations through a modeling approach. The Soil and Water Assessment Tool (SWAT) hydrologic and crop models were applied in the Big Sunflower River watershed (BSRW; 7660 km2) within the Yazoo River Basin...

Soil property changes during loblolly pine production

Treesearch

R. Wayne Skaggs; Devendra M. Amatya; G.M. Chescheir; Christine D. Blanton

2006-01-01

Three watersheds, each approximately 25 ha, were instrumented to measure and record drainage rate, water table depth, rainfall and meteorological data. Data continuously collected on the site since 1988 include response of hydrologic and water quality variables for nearly all growth stages of a Loblolly pine plantation. Data for drainage outflow rates and water table...

Understanding transformations in agriculture in south India through the quantification of productivity, equity, and resilience

NASA Astrophysics Data System (ADS)

Penny, G.; Srinivasan, V.; Thompson, S. E.

2017-12-01

Rapid acceleration of human-water interactions have been identified in many regions of the world, often resulting in reduced water security. In the Arkavathy watershed adjacent to Bangalore, India, environmental and human systems have collectively experienced major transformations since the initiation of sustainable agriculture near the beginning of the Holocene. We reconstruct a narrative history of water security in the Arkavathy, focusing on quantitative metrics of productivity, equity, and resilience. Over this time period, the system can be separated into multiple distinct eras characterized by the dominant practices of agriculture and water management, including the unmanaged (natural) plant ecology of the region, followed by subsistence farming, tank irrigation, construction of large reservoirs, groundwater depletion, and decentralized adaptation. Each of these eras was initiated by a combination of external drivers (e.g., climate, technology) and internal drivers (e.g., demand for food and water). The last fifty years have been characterized by rapid increase in productivity largely sustained by expansion of groundwater irrigation and increasing demand from the rapidly urbanizing Bangalore. Equity initially increased with the introduction of groundwater irrigation and the increased access to irrigation supply. As the water table declined and groundwater irrigation became less affordable, resilience of the system decreased and was followed by a decrease in equity and productivity, with wealthier farmers reaping the benefits and poorer farmers unable to afford access to groundwater. Absent meaningful changes to water rights policy, the system appears to be trending towards a new, undesirable equilibrium characterized by high inequality, moderate productivity (concentrated among the wealthiest farmers), and low resilience.

Combining the Neuman and Boulton models for flow to a well in an unconfined aquifer

USGS Publications Warehouse

Moench, Allen F.

1995-01-01

A Laplace transform solution is presented for flow to a well in a homogeneous, water-table aquifer with noninstanta-neous drainage of water from the zone above the water table. The Boulton convolution integral is combined with Darcy's law and used as an upper boundary condition to replace the condition used by Neuman. Boulton's integral derives from the assumption that water drained from the unsaturated zone is released gradually in a manner that varies exponentially with time in response to a unit decline in hydraulic head, whereas the condition used by Newman assumes that the water is released instantaneously. The result is a solution that reduces to the solution obtained by Neuman as the rate of release of water from the zone above the water table increases. A dimensionless fitting parameter, γ, is introduced that incorporates vertical hydraulic conductivity, saturated thickness, specific yield, and an empirical constant α1, similar to Boulton's α. Results show that theoretical drawdown in water-table piezometers is amplified by noninstantaneous drainage from the unsaturated zone to a greater extent than drawdown in piezometers located at depth in the saturated zone. This difference provides a basis for evaluating γ by type-curve matching in addition to the other dimensionless parameters. Analysis of drawdown in selected piezometers from the published results of two aquifer tests conducted in relatively homogeneous glacial outwash deposits but with significantly different hydraulic conductivities reveals improved comparison between the theoretical type curves and the hydraulic head measured in water-table piezometers.

Terrestrial Responses to Variability in the Southern Westerlies Inferred from Deep Holocene Peat Archives

NASA Astrophysics Data System (ADS)

Hughes, P. D. M.; Mauquoy, D.; van Bellen, S.; Roland, T. P.; Loader, N.; Street-Perrott, F. A.; Daley, T.

2017-12-01

The deep ombrotrophic peat bogs of Chile are located throughout the latitudes dominated by the southern westerly wind belt. The domed surfaces of these peatlands make them sensitive to variability in summer atmospheric moisture balance and the near-continuous accumulation of deep peat strata throughout the Holocene to the present day means that these sites provide undisturbed archives of palaeoclimatic change. We have reconstructed late-Holocene bog water table depths - which can be related to changes in the regional balance of precipitation to evaporation (P-E) - from a suite of peat bogs located in three areas of Tierra del Feugo, Chile, under the main path of the SWWB. Water-table depths were reconstructed from sub-fossil testate amoebae assemblages using a conventional transfer function to infer past water-table depths, based on taxonomic classification of tests but also an innovative trait-based transfer function to infer the same parameter. Water table reconstructions derived from the two methods were consistent within sites. They show that mire water tables have been relatively stable in the last 2000 years across Tierra del Feugo. Higher water table levels, most probably indicating increased effective precipitation, were found between c. 1400 and 900 cal. BP., whereas a consistent drying trend was reconstructed across the region in the most recent peat strata. This shift may represent a pronounced regional decrease in precipitation and/or a change to warmer conditions linked to strengthening of the SWWB. However, other factors such as recent thinning of the ozone layer over Tierra del Fuego could have contributed to recent shifts in some testate amoebae species.

Physiological and morphological effects of high water tables on early growth of giant reed ( Arundo donax), elephant grass ( Pennisetum purpureum), energycane and sugarcane ( Saccharum spp.)

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

Jennewein, Stephen Peter

Here, an increasing demand for renewable energy sources has spurred interest in high-biomass crops used for energy production. Species potentially well-suited for biofuel production in the seasonally wet organic Everglades Agricultural Area (EAA) of Florida include giant reed ( Arundo donax), elephant grass ( Pennisetum Purpureum), energycane ( Saccharum spp.), and sugarcane ( Saccharum spp.). The objectives in this study were to evaluate the role of fluctuating water tables on the morphology, physiology, and early season growth of these four genotypes. The candidate genotypes were grown in a greenhouse under three water table depths, defined by distance of the watermore » table from the soil surface: two constant water tables (-16 cm and -40 cm) along with a flood cycle (2 weeks of flood to the soil level followed by 2 weeks at -40 cm from the soil level). The genotypes included CP 89-2143 (sugarcane), L 79-1002 (energycane), Merkeron (elephant grass), and wild type (giant reed). The experiment was repeated for plant cane, first ratoon, and successive plant cane crop cycles. Reductions in dry matter yield were observed among genotypes subjected to the -40 cm drained, periodically flooded (40F) water table relative to the -40 cm constant (40C) or -16 cm constant (16C). Plant cane dry weights were reduced by 37% in giant reed, 52% in elephant grass, 42% in energycane, and 34% in sugarcane in the 40F compared to 40C water table treatments. Similarly, in the first ratoon crop dry weights were reduced by 29% in giant reed, 42% in elephant grass, 27% in energycane, and 62% in sugarcane. In plant cane and successive plant cane, average total dry weight was greatest for elephant grass whereas ratoon total dry weight was greatest for energycane. Genotype had more pronounced effects on physiological attributes than water table including the highest stomatal conductance and SPAD values in giant reed, and the highest stalk populations in elephant grass and energycane. Aerenchyma presence and volume increased under higher water tables with elephant grass having the greatest aerenchyma production. Because of the high yields and stalk populations in energycane and elephant grass for all crop stages seen in this study, these two genotypes show potential for bioenergy production in the EAA, but field trials are recommended to confirm this.« less

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth.

PubMed

Garrido, Marco; Silva, Paola; Acevedo, Edmundo

2016-01-01

Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the "Pampa del Tamarugal", Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ(13)C and δ(18)O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after experiencing increases in GWD has great value for the implementation of conservation strategies. The thresholds presented in this paper should prove useful for conservation purposes of this unique species.

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

PubMed Central

Garrido, Marco; Silva, Paola; Acevedo, Edmundo

2016-01-01

Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the “Pampa del Tamarugal”, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after experiencing increases in GWD has great value for the implementation of conservation strategies. The thresholds presented in this paper should prove useful for conservation purposes of this unique species. PMID:27064665

Nutrient transport and transformation beneath an infiltration basin

USGS Publications Warehouse

Sumner, D.M.; Rolston, D.E.; Bradner, L.A.

1998-01-01

Field experiments were conducted to examine nutrient transport and transformation beneath an infiltration basin used for the disposal of treated wastewater. Removal of nitrogen from infiltrating water by denitrification was negligible beneath the basin, probably because of subsurface aeration as a result of daily interruptions in basin loading. Retention of organic nitrogen in the upper 4.6 m of the unsaturated zone (water table depth of approximately 11 m) during basin loading resulted in concentrations of nitrate as much as 10 times that of the applied treated wastewater, following basin 'rest' periods of several weeks, which allowed time for mineralization and nitrification. Approximately 90% of the phosphorus in treated wastewater was removed within the upper 4.6 m of the subsurface, primarily by adsorption reactions, with abundant iron and aluminum oxyhydroxides occurring as soil coatings. A reduction in the flow rate of infiltrating water arriving at the water table may explain the accumulation of relatively coarse (>0.45 ??m), organic forms of nitrogen and phosphorus slightly below the water table. Mineralization and nitrification reactions at this second location of organic nitrogen accumulation contributed to concentrations of nitrate as much as three times that of the applied treated wastewater. Phosphorus, which accumulated below the water table, was immobilized by adsorption or precipitation reactions during basin rest periods.Field experiments were conducted to examine nutrient transport and transformation beneath an infiltration basin used for the disposal of treated wastewater. Removal of nitrogen from infiltrating water by denitrification was negligible beneath the basin, probably because of subsurface aeration as a result of daily interruptions in basin loading. Retention of organic nitrogen in the upper 4.6 m of the unsaturated zone (water table depth of approximately 11 m) during basin loading resulted in concentrations of nitrate as much as 10 times that of the applied treated wastewater, following basin 'rest' periods of several weeks, which allowed time for mineralization and nitrification. Approximately 90% of the phosphorus in treated wastewater was removed within the upper 4.6 m of the subsurface, primarily by adsorption reactions, with abundant iron and aluminum oxyhydroxides occurring as soil coatings. A reduction in the flow rate of infiltrating water arriving at the water table may explain the accumulation of relatively coarse (>0.45 ??m), organic forms of nitrogen and phosphorus slightly below the water table. Mineralization and nitrification reactions at this second location of organic nitrogen accumulation contributed to concentrations of nitrate as much as three times that of the applied treated wastewater. Phosphorus, which accumulated below the water table, was immobilized by adsorption or precipitation reactions during basin rest periods.

50 CFR Table 29 to Part 679 - Initial Rockfish QS Pools

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial Rockfish QS Pools 29 Table 29 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679...

Insights from 14C into C loss pathways in degraded peatlands

NASA Astrophysics Data System (ADS)

Evans, Martin; Evans, Chris; Allott, Tim; Stimson, Andrew; Goulsbra, Claire

2016-04-01

Peatlands are important global stores of terrestrial carbon. Lowered water tables due to changing climate and direct or indirect human intervention produce a deeper aerobic zone and have the potential to enhance loss of stored carbon from the peat profile. The quasi continuous accumulation of organic matter in active peatlands means that the age of fluvial dissolved organic carbon exported from peatland systems is related to the source depth in the peat profile. Consequently 14C analysis of DOC in waters draining peatlands has the potential not only to tell us about the source of fluvial carbon and the stability of the peatland but also about the dominant hydrological pathways in the peatland system. This paper will present new radiocarbon determinations from peatland streams draining the heavily eroded peatlands of the southern Pennine uplands in the UK. These blanket peatland systems are highly degraded, with extensive bare peat and gully erosion resulting from air pollution during the industrial revolution, overgrazing, wildfire and climatic changes. Deep and extensive gullying has significantly modified the hydrology of these systems leading to local and more widespread drawdown of water table. 14C data from DOC in drainage waters are presented from two catchments; one with extensive gully erosion and the other with a combination of gully erosion and sheet erosion of the peat. At the gully eroded site DOC in drainage waters is as old as 160 BP but at the site with extensive sheet erosion dates of up to 1069 BP are amongst the oldest recorded from blanket peatland globally These data indicate significant degradation of stored carbon from the eroding peatlands. Initial comparisons of the 14C data with modelled water table for the catchments and depth-age curves for catchment peats suggests that erosion of the peat surface, allowing decomposition of exposed older organic material is a potential mechanism producing aged carbon from the eroded catchment. This mechanism may be as important as changes in hydrological flow pathways within the peat in mobilising aged carbon from the systems.

Investigating the mechanisms of shale porosity development to understand hydrologic controls on hillslope scale weathering in a comparison across CZOs

NASA Astrophysics Data System (ADS)

Gu, X.; Rempe, D.; Brantley, S. L.

2016-12-01

The spatial distribution of weathered rock across actively eroding landscapes strongly influences how water and solutes are routed throughout the landscape. To understand the controls on the evolution of weathering profiles that underlie hilly and mountainous regions, we investigated the porosity formation and chemical weathering of shale (Coastal Belt of the Franciscan Formation) samples from four boreholes at Eel River Critical Zone Observatory (ERCZO) in Northern California. We further compared the characteristics of the shale at ERCZO to the well studied Rose Hill shale at Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) in central Pennsylvania. These two sites have similar mineralogical composition, but are located in vastly different climate and tectonic settings. In particular, the erosion rate at ERCZO (0.2-0.4 mm/yr) is much faster than at SSHCZO (0.015 mm/yr), and the average annual precipitation at ERCZO is higher (1.7 m/yr vs. 1 m/yr at SSHCZO). However, neutron scattering experiments show nearly identical bedrock porosities (3.1-4.6%) of parent rock. Analysis of the chemical and mineralogical compositions of samples throughout the weathering profile reveal that, at both sites, chemical weathering reactions occur at similar depths despite large differences in erosion rate: 1) carbonate and pyrite deplete sharply near the water table. 2) Chlorite oxidation also initiates near water table but shows a wider reaction front. 3) Illite dissolution occurs near the land surface. In both settings, the interface between weathered and unweathered rock roughly coincides with the water table and the porosity and water-accessibility increase toward the land surface. However, at ERCZO, the porosity and the density of micro-fractures are higher in the weathered zone than observed at SSHCZO. It is possible that both sites are moving toward a balance between rates of erosion and weathering advance, and that higher density of microfractures at the rapidly eroding ERCZO promotes faster water infiltration and faster weathering advance relative to the more slowly eroding SSHCZO. Further investigation of the origin and role of these microfractures is needed to understand the interplay between climate, erosion, and weathering that controls hillslope weathering profiles.

A Mathematical View of Water Table Fluctuations in a Shallow Aquifer in Brazil.

PubMed

Neto, Dagmar C; Chang, Hung K; van Genuchten, Martinus Th

2016-01-01

Detailed monitoring of the groundwater table can provide important data about both short- and long-term aquifer processes, including information useful for estimating recharge and facilitating groundwater modeling and remediation efforts. In this paper, we presents results of 4 years (2002 to 2005) of monitoring groundwater water levels in the Rio Claro Aquifer using observation wells drilled at the Rio Claro campus of São Paulo State University in Brazil. The data were used to follow natural periodic fluctuations in the water table, specifically those resulting from earth tides and seasonal recharge cycles. Statistical analyses included methods of time-series analysis using Fourier analysis, cross-correlation, and R/S analysis. Relationships could be established between rainfall and well recovery, as well as the persistence and degree of autocorrelation of the water table variations. We further used numerical solutions of the Richards equation to obtain estimates of the recharge rate and seasonable groundwater fluctuations. Seasonable soil moisture transit times through the vadose zone obtained with the numerical solution were very close to those obtained with the cross-correlation analysis. We also employed a little-used deep drainage boundary condition to obtain estimates of seasonable water table fluctuations, which were found to be consistent with observed transient groundwater levels during the period of study. © 2015, National Ground Water Association.

Wetland Resiliency: How does multi-year water table level decline and recovery influence carbon dioxide and methane fluxes?

NASA Astrophysics Data System (ADS)

Pugh, C.; Reed, D. E.; Desai, A. R.; Sulman, B. N.

2016-12-01

Wetlands play a disproportionately large role in the global carbon budget, and individual wetlands can fluctuate between carbon sinks and sources depending on factors such as hydrology, biogeochemistry, and land use. Although much research has been done on wetland biogeochemical cycles, there is a lack of experimental evidence concerning how changes in wetland hydrology influence these cycles over interannual timescales. Over a seven-year period, Sulman et al. (2009) found that a drought-induced declining water table at a shrub wetland in northern Wisconsin coincided with increased ecosystem respiration (ER) and gross ecosystem productivity (GEP) (Sulman et al. 2009). Since then, however, the average water table level at this site has begun to increase, thus allowing a unique opportunity to explore how wetland carbon storage is impacted by water table recovery. With the addition of three more years of eddy covariance observations post recovery and new methane flux observations, we found that water table level no longer had a significant correlation with GEP, ER, or methane flux. Air temperature, however, had a strong correlation with all three. Average methane flux stayed relatively constant under 14 °C, before increasing an order of magnitude from 3.7 nmol m-2 s-1 in April to 36 nmol m-2 s-1 in July. These results suggest that, over decadal timescales, temperature, rather than water level, is a stronger limiting factor for both aerobic and anaerobic respiration in shrub fen wetlands. Wetlands play a disproportionately large role in the global carbon budget, and individual wetlands can fluctuate between carbon sinks and sources depending on factors such as hydrology, biogeochemistry, and land use. Although much research has been done on wetland biogeochemical cycles, there is a lack of experimental evidence concerning how changes in wetland hydrology influence these cycles over interannual timescales. Over a seven-year period, Sulman et al. (2009) found that a drought-induced declining water table at a shrub wetland in northern Wisconsin coincided with increased ecosystem respiration (ER) and gross ecosystem productivity (GEP) (Sulman et al. 2009). Since then, however, the average water table level at this site has begun to increase, thus allowing a unique opportunity to explore how wetland carbon storage is impacted by water table recovery. With the addition of three more years of eddy covariance observations post recovery and new methane flux observations, we found that water table level no longer had a significant correlation with GEP, ER, or methane flux. Air temperature, however, had a strong correlation with all three. Average methane flux stayed relatively constant under 14 °C, before increasing an order of magnitude from 3.7 nmol m-2 s-1 in April to 36 nmol m-2 s-1 in July. These results suggest that, over decadal timescales, temperature, rather than water level, is a stronger limiting factor for both aerobic and anaerobic respiration in shrub fen wetlands.

Water-table and potentiometric-surface altitudes of the upper glacial, Magothy, and Lloyd aquifers on Long Island, New York, in March-April 2000, with a summary of hydrogeologic conditions

USGS Publications Warehouse

Busciolano, Ronald J.

2002-01-01

The three main water-bearing units on Long Island, New York--the upper glacial aquifer (water table) and the underlying Magothy and Lloyd aquifers--are the sole source of water supply for more than 3 million people. Water-table and potentiometric-surface altitudes were contoured from water-level measurements made at 394 observation, public-supply, and industrial-supply wells during March-April 2000. In general, water-level altitudes in the upper glacial, Magothy, and Lloyd aquifers were lower throughout most parts of Long Island than those measured during March-April 1997. Changes in altitude during this period ranged from an increase of about 6 feet in the Magothy aquifer in southwestern Nassau County to a decrease of more than 8 feet in the upper glacial aquifer in eastern Suffolk County.

Bathymetric maps and water-quality profiles of Table Rock and North Saluda Reservoirs, Greenville County, South Carolina

USGS Publications Warehouse

Clark, Jimmy M.; Journey, Celeste A.; Nagle, Doug D.; Lanier, Timothy H.

2014-01-01

Lakes and reservoirs are the water-supply source for many communities. As such, water-resource managers that oversee these water supplies require monitoring of the quantity and quality of the resource. Monitoring information can be used to assess the basic conditions within the reservoir and to establish a reliable estimate of storage capacity. In April and May 2013, a global navigation satellite system receiver and fathometer were used to collect bathymetric data, and an autonomous underwater vehicle was used to collect water-quality and bathymetric data at Table Rock Reservoir and North Saluda Reservoir in Greenville County, South Carolina. These bathymetric data were used to create a bathymetric contour map and stage-area and stage-volume relation tables for each reservoir. Additionally, statistical summaries of the water-quality data were used to provide a general description of water-quality conditions in the reservoirs.

Landsliding in partially saturated materials

USGS Publications Warehouse

Godt, J.W.; Baum, R.L.; Lu, N.

2009-01-01

[1] Rainfall-induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards. However, capturing their occurrence with scientific instrumentation in a natural setting is extremely rare. The prevailing thinking on landslide initiation, particularly for those landslides that occur under intense precipitation, is that the failure surface is saturated and has positive pore-water pressures acting on it. Most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table. By monitoring the pore water and soil suction response to rainfall, we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting. We show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials. Copyright 2009 by the American Geophysical Union.

A multi-method study of regional groundwater circulation in the Ordos Plateau, NW China

NASA Astrophysics Data System (ADS)

Jiang, Xiao-Wei; Wan, Li; Wang, Xu-Sheng; Wang, Dan; Wang, Heng; Wang, Jun-Zhi; Zhang, Hong; Zhang, Zhi-Yuan; Zhao, Ke-Yu

2018-01-01

The Ordos Basin is one of the most intensively studied groundwater basins in China. The Ordos Plateau, located in the north part of the Ordos Basin, is ideal to study the pattern of regional groundwater circulation induced by water-table undulations due to the wavy topography and the relatively simple aquifer systems with macroscopically homogeneous sandstone. In catchments located near the first-order divide, the water table is found to be a subdued replica of the topography, and the nonclosed water-table contours in topographic highs of a catchment are indicative of regional groundwater outflow to other catchments. In topographic lows, groundwater-fed lakes/rivers, topography-driven flowing wells, water-loving and/or salt-tolerant vegetation, and soap holes are all indicative of discharge areas. In discharge areas, although groundwater inflow from recharge areas is relatively stable, seasonal variations in groundwater recharge and evapotranspiration lead to significant seasonal fluctuations in the water table, which can be used to estimate groundwater inflow and evapotranspiration rates based on water balance at different stages of water-table change. In the lowest reaches of a complex basin, superposition of local flow systems on regional flow systems has been identified based on groundwater samples collected from wells with different depths and geophysical measurements of apparent resistivity, both of which can be used for characterizing groundwater flow systems. This study enhances understanding of the pattern of regional groundwater circulation in the Ordos Plateau, and also tests the effectiveness of methods for groundwater flow-system characterization.

Groundwater influence on soil moisture memory and land-atmosphere interactions over the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Martinez-de la Torre, Alberto; Miguez-Macho, Gonzalo

2017-04-01

We investigate the memory introduced in soil moisture fields by groundwater long timescales of variation in the semi-arid regions of the Iberian Peninsula with the LEAFHYDRO soil-vegetation-hydrology model, which includes a dynamic water table fully coupled to soil moisture and river flow via 2-way fluxes. We select a 10-year period (1989-1998) with transitions from wet to dry to again wet long lasting conditions and we carry out simulations at 2.5 km spatial resolution forced by ERA-Interim and a high-resolution precipitation analysis over Spain and Portugal. The model produces a realistic water table that we validate with hundreds of water table depth observation time series (ranging from 4 to 10 years) over the Iberian Peninsula. Modeled river flow is also compared to observations. Over shallow water table regions, results highlight the groundwater buffering effect on soil moisture fields over dry spells and long-term droughts, as well as the slow recovery of pre-drought soil wetness once climatic conditions turn wetter. Groundwater sustains river flow during dry summer periods. The longer lasting wet conditions in the soil when groundwater is considered increase summer evapotranspiration, that is mostly water-limited. Our results suggest that groundwater interaction with soil moisture should be considered for climate seasonal forecasting and climate studies in general over water-limited regions where shallow water tables are significantly present and connected to land surface hydrology.

Ergodicity of the generalized lemon billiards

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

Chen, Jingyu; Mohr, Luke; Zhang, Hong-Kun, E-mail: hongkun@math.umass.edu

2013-12-15

In this paper, we study a two-parameter family of convex billiard tables, by taking the intersection of two round disks (with different radii) in the plane. These tables give a generalization of the one-parameter family of lemon-shaped billiards. Initially, there is only one ergodic table among all lemon tables. In our generalized family, we observe numerically the prevalence of ergodicity among the some perturbations of that table. Moreover, numerical estimates of the mixing rate of the billiard dynamics on some ergodic tables are also provided.

76 FR 774 - Folding Metal Tables and Chairs From the People's Republic of China: Notice of Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-06

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-868] Folding Metal Tables and... review of the antidumping duty order on folding metal tables and chairs from the People's Republic of China (``PRC''). See Folding Metal Tables and Chairs: Initiation of New Shipper Review, 75 FR 44767...

Integrated hydrologic modeling: Effects of spatial scale, discretization and initialization

NASA Astrophysics Data System (ADS)

Seck, A.; Welty, C.; Maxwell, R. M.

2011-12-01

Groundwater discharge contributes significantly to the annual flows of Chesapeake Bay tributaries and is presumed to contribute to the observed lag time between the implementation of management actions and the environmental response in the Chesapeake Bay. To investigate groundwater fluxes and flow paths and interaction with surface flow, we have developed a fully distributed integrated hydrologic model of the Chesapeake Bay Watershed using ParFlow. Here we present a comparison of model spatial resolution and initialization methods. We have studied the effect of horizontal discretization on overland flow processes at a range of scales. Three nested model domains have been considered: the Monocacy watershed (5600 sq. km), the Potomac watershed (92000 sq. km) and the Chesapeake Bay watershed (400,000 sq. km). Models with homogeneous subsurface and topographically-derived slopes were evaluated at 500-m, 1000-m, 2000-m, and 4000-m grid resolutions. Land surface slopes were derived from resampled DEMs and corrected using stream networks. Simulation results show that the overland flow processes are reasonably well represented with a resolution up to 2000 m. We observe that the effects of horizontal resolution dissipate with larger scale models. Using a homogeneous model that includes subsurface and surface terrain characteristics, we have evaluated various initialization methods for the integrated Monocacy watershed model. This model used several options for water table depths and two rainfall forcing methods including (1) a synthetic rainfall-recession cycle corresponding to the region's average annual rainfall rate, and (2) an initial shut-off of rainfall forcing followed by a rainfall-recession cycling. Results show the dominance of groundwater generated runoff during a first phase of the simulation followed by a convergence towards more balanced runoff generation mechanisms. We observe that the influence of groundwater runoff increases in dissected relief areas characterized by high slope magnitudes. This is due to the increase in initial water table gradients in these regions. As a result, in the domain conditions for this study, an initial shut-off of rainfall forcing proved to be the more efficient initialization method. The initialized model is then coupled with a Land Surface Model (CLM). Ongoing work includes coupling a heterogeneous subsurface field with spatially variable meteorological forcing using the National Land Data Assimilation System (NLDAS) data products. Seasonal trends of groundwater levels for current and pre-development conditions of the basin will be compared.

US EPA OPTIMAL WELL LOCATOR (OWL): A SCREENING TOOL FOR EVALUATING LOCATIONS OF MONITORING WELLS

EPA Science Inventory

The Optimal Well Locator (OWL): uses linear regression to fit a plane to the elevation of the water table in monitoring wells in each round of sampling. The slope of the plane fit to the water table is used to predict the direction and gradient of ground water flow. Along with ...

Ground-water resources of the North Beach Peninsula, Pacific County, Washington

USGS Publications Warehouse

Tracy, James V.

1977-01-01

The anticipated water demand of 425 million gallons per year for the North Brach Peninsula, Pacific County, Wash., can be met by properly developing the ground-water supplies of the area 's water-table aquifer. Of the approximately 77 inches of annual precipitation on the peninsula, an estimated 23 inches is lost to evapotranspiration, and approximately 36 inches is discharged by the water-table aquifer into the ocean and bay. The remaining water either runs off the surface or is leaked to a deeper aquifer that ultimately discharges to the ocean. At least 12 inches of the water that discharges naturally through the aquifer is available for additional development. This quantity of water is approximately equivalent to 860,000 gallons per day. Wells spaced at least 1,000 feet apart along the major axis of the peninsula and pumped at average rates of no more than 80 gallons per minute could ensure that water-level declines do not exceed 6 feet near the wells and 1 foot at the shoreline, thereby preventing seawater intrusion. Lowering of the water table may be beneficial in reducing waterlogging problems, but care must be taken not to lower the levels near cranberry bogs, which require a shallow water table. Treatment of the otherwise good quality water for iron may be required, as about 75 percent of the well water sampled from the aquifer had iron concentrations in excess of limits recommended by the U.S. Environmental Protection Agency. (Woodard-USGS)

Effects of high-rate wastewater spray disposal on the water-table aquifer, Hilton Head Island, South Carolina

USGS Publications Warehouse

Speiran, G.K.

1985-01-01

A study by the U.S. Geological Survey from April 1982 through December 1983 evaluated the effects of high-rate disposal of treated wastewater on the water table aquifer, Hilton Head Island, South Carolina. Flooding of topographically low areas resulted from the application of 10.8 inches of wastewater in 10 days in January 1983. The water table remained 2-1/2 to 5-1/2 feet below land surface when wastewater was applied at rates of 5 inches per week in August and December 1983. (USGS)

Investigation of remote sensing to detect near-surface groundwater on irrigated lands

NASA Technical Reports Server (NTRS)

Ryland, D. W.; Schmer, F. A.; Moore, D. G.

1975-01-01

The application of remote sensing techniques was studied for detecting areas with high water tables in irrigated agricultural lands. Aerial data were collected by the LANDSAT-1 satellite and aircraft over the Kansas/Bostwick Irrigation District in Republic and Jewell Counties, Kansas. LANDSAT-1 data for May 12 and August 10, 1973, and aircraft flights (midday and predawn) on August 10 and 11, 1973, and June 25 and 26, 1974, were obtained. Surface and water table contour maps and active observation well hydrographs were obtained from the Bureau of Reclamation for use in the analysis. Results of the study reveal that LANDSAT-1 data (May MSS band 6 and August MSS band 7) correlate significantly (0.01 level) with water table depth for 144 active observation wells located throughout the Kansas/Bostwick Irrigation District. However, a map of water table depths of less than 1.83 meters prepared from the LANDSAT-1 data did not compare favorably with a map of seeped lands of less than 1.22 m (4 feet) to the water table. Field evaluation of the map is necessary for a complete analysis. Analysis of three fields on a within or single-field basis for the 1973 LANDSAT-1 data also showed significant correlation results.

Mapping water table depth using geophysical and environmental variables.

PubMed

Buchanan, S; Triantafilis, J

2009-01-01

Despite its importance, accurate representation of the spatial distribution of water table depth remains one of the greatest deficiencies in many hydrological investigations. Historically, both inverse distance weighting (IDW) and ordinary kriging (OK) have been used to interpolate depths. These methods, however, have major limitations: namely they require large numbers of measurements to represent the spatial variability of water table depth and they do not represent the variation between measurement points. We address this issue by assessing the benefits of using stepwise multiple linear regression (MLR) with three different ancillary data sets to predict the water table depth at 100-m intervals. The ancillary data sets used are Electromagnetic (EM34 and EM38), gamma radiometric: potassium (K), uranium (eU), thorium (eTh), total count (TC), and morphometric data. Results show that MLR offers significant precision and accuracy benefits over OK and IDW. Inclusion of the morphometric data set yielded the greatest (16%) improvement in prediction accuracy compared with IDW, followed by the electromagnetic data set (5%). Use of the gamma radiometric data set showed no improvement. The greatest improvement, however, resulted when all data sets were combined (37% increase in prediction accuracy over IDW). Significantly, however, the use of MLR also allows for prediction in variations in water table depth between measurement points, which is crucial for land management.

The influence of irrigation-induced water table fluctuation on iron redistribution and arsenic immobilization within the unsaturation zone.

PubMed

Chi, Zeyong; Xie, Xianjun; Pi, Kunfu; Wang, Yanxin; Li, Junxia; Qian, Kun

2018-05-08

Given the long-term potential risk of arsenic (As)-contaminated agricultural soil to public health, the redistribution of iron (Fe) and immobilization of As within the unsaturation zone during irrigation and consequent water table fluctuations were studied via a column experiment and corresponding geochemical modeling. Experimental results show that As and Fe accumulated significantly at the top of the column during irrigation. A tremendous increase in As and Fe accumulation rates exists after water table recovery. It was deduced that Fe(II) and As(III) were oxidized directly by O 2 at the period of low water table. But the production of hydroxyl radical (OH) was promoted at the period of high water table due to the oxidation of adsorbed Fe(II). The generated OH further accelerate the oxidation of Fe(II) and As(III). Moreover, the combination of As and Fe is more stronger at the top of the column due to the transformation of combined states of As from surface complexation into surface precipitation with the growth of Fe(III) minerals. This study details the processes and mechanisms of As and Fe immobilization within the unsaturation zone during different irrigation periods and accordingly provides some insights to mitigate As accumulation in topsoil. Copyright © 2018 Elsevier B.V. All rights reserved.

40 CFR Table 3 to Subpart Ooo - Fugitive Emission Limits

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Fugitive Emission Limits 3 Table 3 to... Processing Plants Subpt. OOO, Table 3 Table 3 to Subpart OOO—Fugitive Emission Limits Table 3 to Subpart OOO...; andPeriodic inspections of water sprays according to § 60.674(b) and § 60.676(b); and A repeat...

40 CFR Table 3 to Subpart Ooo - Fugitive Emission Limits

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Fugitive Emission Limits 3 Table 3 to... Processing Plants Subpt. OOO, Table 3 Table 3 to Subpart OOO—Fugitive Emission Limits Table 3 to Subpart OOO...; andPeriodic inspections of water sprays according to § 60.674(b) and § 60.676(b); and A repeat...

Lateral water flux in the unsaturated zone: A mechanism for the formation of spatial soil heterogeneity in a headwater catchment

Treesearch

John P. Gannon; Kevin J. McGuire; Scott W. Bailey; Rebecca R. Bourgault; Donald S. Ross

2017-01-01

Measurements of soil water potential and water table fluctuations suggest that morphologically distinct soils in a headwater catchment at the Hubbard Brook Experimental Forest in New Hampshire formed as a result of variations in saturated and unsaturated hydrologic fluxes in the mineral soil. Previous work showed that each group of these soils had distinct water table...

Potential groundwater contribution to Amazon evapotranspiration

NASA Astrophysics Data System (ADS)

Fan, Y.; Miguez-Macho, G.

2010-07-01

Climate and land ecosystem models simulate a dry-season vegetation stress in the Amazon forest, but observations show enhanced growth in response to higher radiation under less cloudy skies, indicating an adequate water supply. Proposed mechanisms include larger soil water store and deeper roots in nature and the ability of roots to move water up and down (hydraulic redistribution). Here we assess the importance of the upward soil water flux from the groundwater driven by capillarity. We present a map of water table depth from observations and groundwater modeling, and a map of potential capillary flux these water table depths can sustain. The maps show that the water table beneath the Amazon can be quite shallow in lowlands and river valleys (<5 m in 36% and <10 m in 60% of Amazonia). The water table can potentially sustain a capillary flux of >2.1 mm day-1 to the land surface averaged over Amazonia, but varies from 0.6 to 3.7 mm day-1 across nine study sites. Current models simulate a large-scale reduction in dry-season photosynthesis under today's climate and a possible dieback under projected future climate with a longer dry season, converting the Amazon from a net carbon sink to a source and accelerating warming. The inclusion of groundwater and capillary flux may modify the model results.

Hydrogeologic characteristics and geospatial analysis of water-table changes in the alluvium of the lower Arkansas River Valley, southeastern Colorado, 2002, 2008, and 2015

USGS Publications Warehouse

Holmberg, Michael J.

2017-05-15

The U.S. Geological Survey in cooperation with the Lower Arkansas Valley Water Conservancy District measures groundwater levels periodically in about 100 wells completed in the alluvial material of the Arkansas River Valley in Pueblo, Crowley, Otero, Bent, and Prowers Counties in southeastern Colorado, of which 95 are used for the analysis in this report. The purpose of this report is to provide information to water-resource administrators, managers, planners, and users about groundwater characteristics in the alluvium of the lower Arkansas Valley extending roughly 150 miles between Pueblo Reservoir and the Colorado-Kansas State line. This report includes three map sheets showing (1) bedrock altitude at the base of the alluvium of the lower Arkansas Valley; (2) estimated spring-to-spring and fall-to-fall changes in water-table altitude between 2002, 2008, and 2015; and (3) estimated saturated thickness in the alluvium during spring and fall of 2002, 2008, and 2015, and thickness of the alluvium in the lower Arkansas Valley. Water-level changes were analyzed by geospatial interpolation methods.Available data included all water-level measurements made between January 1, 2001, and December 31, 2015; however, only data from fall and spring of 2002, 2008, and 2015 are mapped in this report. To account for the effect of John Martin Reservoir in Bent County, Colorado, lake levels at the reservoir were assigned to points along the approximate shoreline and were included in the water-level dataset. After combining the water-level measurements and lake levels, inverse distance weighting was used to interpolate between points and calculate the altitude of the water table for fall and spring of each year for comparisons. Saturated thickness was calculated by subtracting the bedrock surface from the water-table surface. Thickness of the alluvium was calculated by subtracting the bedrock surface from land surface using a digital elevation model.In order to analyze the response of the alluvium to varying environmental and anthropogenic conditions, the percentage of area of the lower Arkansas Valley showing an absolute change of 3 feet or less was calculated for each of the six water-table altitude change maps. For fall water-table altitude change maps, the periods between 2002 and 2008, 2008 and 2015, and 2002 and 2015 showed that 86.5 percent, 85.2 percent, and 66.3 percent of the study area, respectively, showed a net change of 3 feet or less. In the spring water-table altitude change maps these periods showed a net change of 3 feet or less in 94.4 percent, 96.1 percent, and 90.2 percent of the study area, respectively. While the estimated change in water-table altitude was slightly greater and more variable in fall-to-fall comparisons, these high percentages of area with relatively small net changes indicated that, at least in comparisons of the years presented, there was not a large amount of fluctuation in the altitude of the water table.The saturated thickness in the lower Arkansas Valley was between 25 and 50 feet in 34.4 to 35.9 percent of the study area, depending on the season and year. Between 30.2 and 35.6 percent of the area showed saturated thicknesses between 0 and 25 feet. Less than 1 percent of the area showed a saturated thickness greater than 200 feet in all mapped seasons and years.

Study of hydro-saline characteristics of soils a palm grove in basin of Ouargla (Northern Algerian Sahara)

NASA Astrophysics Data System (ADS)

Rezagui, D.; Bouhoun, M. Daddi; Boutoutaou, D.; Djaghoubi, A.

2016-07-01

Saharan soils are often faced with several problems of development, taking account the hydro-edaphic constraints, mainly of hydric types by water table, mechanical by gypso-calcareous crusts and saline by irrigation waters and upwelling of water table. Our work consists in doing a soil characterization of a palm grove in Ouargla in order to study the constraints hydro-halomorphes. The results show that irrigation water by two plies of Senonian and Mioplcène had a high salinity with a value of 2.83 and 5.10 dS.m-1 respectively. The conduct of irrigation is traditional random of submersion type. The palm grove has a poor drainage with a level of water table 156.67±15.71 cm and salinity of 31.37±34.04 dS.m-1. The drains are open type and their maintenance is not regular. This situation of management of irrigation-drainage promotes the upwelling of water table and the waterlogging in soils. The study of soil profiles shows the existence of mechanical obstruction of gypso-calcareous crusts which limit the entrenchment of the date palms and the leaching of salts. Soil salinity is excessive in profiles with a range of 8.98 ± 4.58 dS.m-1. This accumulation of salts is due to the dynamic ascending and descending of salts respectively under the effect of upwelling of water table and leaching by irrigation. The salinization, the upwelling of water table and the presence of gypso-calcareous crusts recorded in Ouargla testify to a degradation hydro-halomorphe and mechanic of soil which constitute the major constraints in the management of system irrigation-drainage and sustainable agricultural development of the palm groves of the basin of Ouargla. Some hydro-agricultural planning are necessary to apply in the oasis to improve the hydro-mechanical properties of soils in order to reduce their degradation.

Representing northern peatland microtopography and hydrology within the Community Land Model

DOE PAGES

Shi, Xiaoying; Thornton, Peter E.; Ricciuto, Daniel M.; ...

2015-11-12

Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. Furthermore, the new model provides improved predictive capacity for seasonal hydrological dynamics in northern peatlands, and provides a useful foundation for investigation of northern peatland carbon exchange.« less

Representing northern peatland microtopography and hydrology within the Community Land Model

DOE PAGES

Shi, X.; Thornton, P. E.; Ricciuto, D. M.; ...

2015-02-20

Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics in northern peatlands, and provides a useful foundation for investigation of northern peatland carbon exchange.« less

Geochemical evolution of acidic ground water at a reclaimed surface coal mine in western Pennsylvania

USGS Publications Warehouse

Cravotta,, Charles A.

1991-01-01

Concentrations of dissolved sulfate and acidity in ground water increase downflow in mine spoil and underlying bedrock at a reclaimed surface coal mine in the bituminous field of western Pennsylvania. Elevated dissolved sulfate and negligible oxygen in ground water from bedrock about 100 feet below the water table suggest that pyritic sulfur is oxidized below the water table, in a system closed to oxygen. Geochemical models for the oxidation of pyrite (FeS2) and production of sulfate (SO42-) and acid (H+) are presented to explain the potential role of oxygen (O2) and ferric iron (Fe3+) as oxidants. Oxidation of pyrite by O2 and Fe3+ can occur under oxic conditions above the water table, whereas oxidation by Fe3+ also can occur under anoxic conditions below the water table. The hydrated ferric-sulfate minerals roemerite [Fe2+Fe43+(SO4)4·14H2O], copiapite [Fe2+Fe43+(SO4)6(OH)2·20H20], and coquimbite [Fe2(SO4)3·9H2O] were identified with FeS2 in coal samples, and form on the oxidizing surface of pyrite in an oxic system above the water table. These soluble ferric-sulfate 11 salts11 can dissolve with recharge waters or a rising water table releasing Fe3+, SO42-. and H+, which can be transported along closed-system ground-water flow paths to pyrite reaction sites where O2 may be absent. The Fe3+ transported to these sites can oxidize pyritic sulfur. The computer programs WATEQ4F and NEWBAL were used to compute chemical speciation and mass transfer, respectively, considering mineral dissolution and precipitation reactions plus mixing of waters from different upflow zones. Alternative mass-balance models indicate that (a) extremely large quantities of O2, over 100 times its aqueous solubility, can generate the observed concentrations of dissolved SO42- from FeS2, or (b) under anoxic conditions, Fe3+ from dissolved ferric-sulfate minerals can oxidize FeS2 along closed-system ground-water flow paths. In a system open to O2, such as in the unsaturated zone, the aqueous solubility of O2 is not limiting, and oxidation of pyrite by O2 and Fe3+ accounts for most SO42- and Fe2+ observed in acidic ground water. However, in a system closed to O2, such as in the saturated zone, O2 solubility is limiting; hence, ferric oxidation of pyrite is a reasonable explanation for the observed elevated SO42- with increasing depth below the water table.

Growth and nutrient status of black spruce seedlings as affected by water table depth

Treesearch

Miroslaw M. Czapowskyj; Robert V. Rourke; Walter J. Grant; Walter J. Grant

1986-01-01

The objective of this study was to determine the effect of different soil water table levels on growth, biomass production, and nutrient accumulation in black spruce seedlings growing under greenhouse conditions over three growing seasons after transplanting.

Effect of water content on stability of landslides triggered by earthquakes

NASA Astrophysics Data System (ADS)

Beyabanaki, S.; Bagtzoglou, A. C.; Anagnostou, E. N.

2013-12-01

Earthquake- triggered landslides are one of the most important natural hazards that often result in serious structural damage and loss of life. They are widely studied by several researchers. However, less attention has been focused on soil water content. Although the effect of water content has been widely studied for rainfall- triggered landslides [1], much less attention has been given to it for stability analysis of earthquake- triggered landslides. We developed a combined hydrology and stability model to investigate effect of soil water content on earthquake-triggered landslides. For this purpose, Bishop's method is used to do the slope stability analysis and Richard's equation is employed to model infiltration. Bishop's method is one the most widely methods used for analyzing stability of slopes [2]. Earthquake acceleration coefficient (EAC) is also considered in the model to analyze the effect of earthquake on slope stability. Also, this model is able to automatically determine geometry of the potential landslide. In this study, slopes with different initial water contents are simulated. First, the simulation is performed in the case of earthquake only with different EACs and water contents. As shown in Fig. 1, initial water content has a significant effect on factor of safety (FS). Greater initial water contents lead to less FS. This impact is more significant when EAC is small. Also, when initial water content is high, landslides can happen even with small earthquake accelerations. Moreover, in this study, effect of water content on geometry of landslides is investigated. For this purpose, different cases of landslides triggered by earthquakes only and both rainfall and earthquake for different initial water contents are simulated. The results show that water content has more significant effect on geometry of landslides triggered by rainfall than those triggered by an earthquake. Finally, effect of water content on landslides triggered by earthquakes during rainfall is investigated. In this study, after different durations of rainfall, an earthquake is applied to the model and the elapsed time in which the FS gets less than one obtains by trial and error. The results for different initial water contents and earthquake acceleration coefficients show that landslides can happen after shorter rainfall duration when water content is greater. If water content is high enough, the landslide occurs even without rainfall. References [1] Ray RL, Jacobs JM, de Alba P. Impact of unsaturated zone soil moisture and groundwater table on slope instability. J. Geotech. Geoenviron. Eng., 2010, 136(10):1448-1458. [2] Das B. Principles of Foundation Engineering. Stanford, Cengage Learning, 2011. Fig. 1. Effect of initial water content on FS for different EACs

Optical Properties of Nanocellulose Dispersions in Water, Dimethylformamide and Poly(Methyl Methacrylate)

DTIC Science & Technology

2013-10-01

measurements for cellulose and PMMA thin- films . ..13  v List of Tables Table 1. Recorded optical data for nanocellulose in water...applications beyond thin films . In particular, the effects of nanocellulose fibers in higher concentrations, processed in different solvents, and...Optical Properties of Nanocellulose Dispersions in Water, Dimethylformamide and Poly(Methyl Methacrylate) by James F. Snyder, Joshua Steele

46 CFR 180.200 - Survival craft-general.

Code of Federal Regulations, 2014 CFR

2014-10-01

... in Table 180.200(c). Table 180.200(c) Route Survival craft requirements Oceans (a) cold water 1—100...(b). Coastwise (a) wood vsls in cold water. (i) 67% IBA—§ 180.204(a)(1). (ii) w/subdivision—100% LF... 20 miles from a harbor of safe refuge) (a) wood vsls in cold water.(i) 67% IBA—§ 180.205(a)(1). (ii...

U.S. EPA OPTIMAL WELL LOCATOR (OWL): A SCREENING TOOL FOR EVALUATING LOCATIONS OF MONITORING WELLS (ROCKY GAP, MD)

EPA Science Inventory

The Optimal Well Locator (OWL): uses linear regression to fit a plane to the elevation of the water table in monitoring wells in each round of sampling. The slope of the plane fit to the water table is used to predict the direction and gradient of ground water flow. Along with ...

Fuel management optimization using genetic algorithms and expert knowledge

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

DeChaine, M.D.; Feltus, M.A.

1996-09-01

The CIGARO fuel management optimization code based on genetic algorithms is described and tested. The test problem optimized the core lifetime for a pressurized water reactor with a penalty function constraint on the peak normalized power. A bit-string genotype encoded the loading patterns, and genotype bias was reduced with additional bits. Expert knowledge about fuel management was incorporated into the genetic algorithm. Regional crossover exchanged physically adjacent fuel assemblies and improved the optimization slightly. Biasing the initial population toward a known priority table significantly improved the optimization.

Strategic considerations in SETI, and a microwave approach. [Search for ExtraTerrestrial Intelligence

NASA Technical Reports Server (NTRS)

Seeger, C. L.

1977-01-01

Plausible options in the search for extraterrestrial intelligence (SETI), and the need to reserve a suitable portion of the EM (microwave) spectrum for SETI research, are discussed. Reasons for selection of a portion of the spectrum, specifically the 'water hole' near 1.5 GHz in the terrestrial microwave window (1-25 GHz), are presented, and competition with various emitters for that band (existing satellite downlink transmissions) is discussed. SETI search policies and options are summarized in a table. Speculative considerations guiding initial phases of the SETI pursuit are discussed.

Evaluation of a mechanistic algorithm to calculate the influence of a shallow water table on hydrology sediment and pesticide transport through vegetative filter strips

NASA Astrophysics Data System (ADS)

Lauvernet, C.; Munoz-Carpena, R.; Carluer, N.

2012-04-01

Natural or introduced areas of vegetation, also known as vegetative filter strips (VFS), are a common environmental control practice to protect surface water bodies from human influence. In Europe, VFS are placed along the water network to protect from agrochemical drift during applications, in addition to runoff control. Their bottomland placement next to the streams often implies the presence of a seasonal shallow water table which can have a profound impact on the efficiency of the buffer zone (Lacas et al. 2005). A physically-based algorithm describing ponded infiltration into soils bounded by a water table, proposed by Salvucci and Enthekabi (1995), was further developed to simulate VFS dynamics by making it explicit in time, account for unsteady rainfall conditions, and by coupling to a numerical overland flow and transport model (VFSMOD) (Munoz-Carpena et al., submitted). In this study, we evaluate the importance of the presence of a shallow water table on filter efficiency (reductions in runoff, sediment and pesticide mass), in the context of all other input factors used to describe the system. Global sensitivity analysis (GSA) was used to rank the important input factors and the presence of interactions, as well as the contribution of the important factors to the output variance. GSA of VSFMOD modified for shallow water table was implemented on 2 sites selected in France because they represent different agro-pedo-climatic conditions for which we can compare the role of the factors influencing the performance of grassed buffer strips for surface runoff, sediment and pesticide removal. The first site at Morcille watershed in the Beaujolais wineyard (Rhône-Alpes) contains a very permeable sandy-clay with water table depth varying with the season (very deep in summer and shallow in winter), with a high slope (20 to 30%), and subject to strong seasonal storms (semi-continental, Mediterranean climate). The second site at La Jailliere (Loire-Atlantique, ARVALIS-Institut du Végétal, mainly wheat and maize) is a poorly permeable medium loamy over clay soil, with possible local shallow water tables, slopes around 3% and mild and rainy winter while summer is cool and wet (temperate, oceanic climate). GSA allowed us to interpret the results from the multivariate Monte-Carlo uncertainty analysis and gain insights on the management and placement of the buffer systems.

Tafilalet OASIS System: Water Resources Management and Investigation by GIS and Groundwater Flow Model

NASA Astrophysics Data System (ADS)

Bouaamlat, I.; Larabi, A.; Faouzi, M.

2014-12-01

The geographical location of Tafilalet oasis system (TOS) in the south of the valley of Ziz (Morocco) offers him a particular advantage on the plane of water potential. The surface water which comes from humid regions of the High Atlas and intercepted by a dam then converged through the watercourse of Ziz towards the plain of the TOS, have created the conditions for the formation of a water table relatively rich with regard to the local climatic conditions (arid climate with recurrent drought). Given the role of the water table in the economic development of the region, a hydrogeological study was conducted to understand the impact of artificial recharge and recurrent droughts on the development of the groundwater reserves of TOS. In this study, a three-dimensional model of groundwater flow was developed for the TOS, to assist the decision makers as a "management tool" in order to assess alternative schemes for development and exploitation of groundwater resources based on the variation of artificial recharge and drought. The results from this numerical investigation of the TOS aquifer shows that the commissioning of the dam to control the flows of extreme flood and good management of water releases, has avoided the losses of irrigation water and consequently the non-overexploitation of the groundwater. So that with one or two water releases per year from the dam of flow rate more than 28 million m3/year it is possible to reconstruct the volume of water abstracted by wells. The idea of lowering water table by pumping wells is not exactly true, as well the development of groundwater abstraction has not prevented the wound of water table in these last years, the pumping wells accompanied more than it triggers the lowering of water table and it is mainly the succession of dry periods causing the decreases of the piezometric level. This situation confirms the important role that groundwater plays as a "buffer" during the drought periods.

A high-resolution land model coupled with groundwater lateral flow, human water regulation and the changes in soil freeze-thaw fronts

NASA Astrophysics Data System (ADS)

Xie, Z.; Zeng, Y.; Liu, S.; Gao, J.; Jia, B.; Qin, P.

2017-12-01

Both anthropogenic water regulation and groundwater lateral flow essentially affect groundwater table patterns. Their relationship is close because lateral flow recharges the groundwater depletion cone, which is induced by over-exploitation. And the movement of frost and thaw fronts (FTFs) affects soil water and thermal characteristics, as well as energy and water exchanges between land surface and the atmosphere. In this study, schemes describing groundwater lateral flow, human water regulation and the changes in soil freeze-thaw fronts were developed and incorporated into the Community Land Model 4.5. Then the model was applied in Heihe River Basin(HRB), an arid and semiarid region, northwest China. High resolution ( 1 km) numerical simulations showed that groundwater lateral flow driven by changes in water heads can essentially change the groundwater table pattern with the deeper water table appearing in the hillslope regions and shallower water table appearing in valley bottom regions and plains. Over the last decade, anthropogenic groundwater exploitation deepened the water table by approximately 2 m in the middle reaches of the HRB and rapidly reduced the terrestrial water storage, while irrigation increased soil moisture by approximately 0.1 m3 m-3. The water stored in the mainstream of the Heihe River was also reduced by human surface water withdrawal. The latent heat flux was increased by 30 W m-2 over the irrigated region, with an identical decrease in sensible heat flux. The simulated groundwater lateral flow was shown to effectively recharge the groundwater depletion cone caused by over-exploitation. The offset rate is higher in plains than mountainous regions. In addition, the simulated FTFs depth compared well with the observed data both in D66 station (permafrost) and Hulugou station (seasonally frozen ground). Over the HRB, the upstream area is permafrost region with maximum thawed depth at 2.5 m and lower region is seasonal frozen ground region with maximum frozen depth at 3 m.

Significant Pre-Accession Factors Predicting Success or Failure During a Marine Corps Officer’s Initial Service Obligation

DTIC Science & Technology

2015-12-01

WAIVERS ..............................................................................................49  APPENDIX C. DESCRIPTIVE STATISTICS ... Statistics of Dependent Variables. .............................................23  Table 6.  Summary Statistics of Academics Variables...24  Table 7.  Summary Statistics of Application Variables ............................................25  Table 8

Water budgets for major streams in the Central Valley, California, 1961-77

USGS Publications Warehouse

Mullen, J.R.; Nady, Paul

1985-01-01

A compilation of annual streamflow data for 20 major stream systems in the central Valley of California, for water years 1961-77, is presented. The water-budget tables list gaged and ungaged inflow from tributaries and canals, diversions, and gaged outflow. Theoretical outflow and gain or loss in a reach are computed. A schematic diagram and explanation of the data are provided for each water-budget table. (USGS)

Delineation of areas contributing groundwater to selected receiving surface water bodies for long-term average hydrologic conditions from 1968 to 1983 for Long Island, New York

USGS Publications Warehouse

Misut, Paul E.; Monti,, Jack

2016-10-05

To assist resource managers and planners in developing informed strategies to address nitrogen loading to coastal water bodies of Long Island, New York, the U.S. Geological Survey and the New York State Department of Environmental Conservation initiated a program to delineate a comprehensive dataset of groundwater recharge areas (or areas contributing groundwater), travel times, and outflows to streams and saline embayments on Long Island. A four-layer regional three-dimensional finite-difference groundwater-flow model of hydrologic conditions from 1968 to 1983 was used to provide delineations of 48 groundwater watersheds on Long Island. Sixteen particle starting points were evenly spaced within each of the 4,000- by 4,000-foot model cells that receive water-table recharge and tracked using forward particle-tracking analysis modeling software to outflow zones. For each particle, simulated travel times were grouped by age as follows: less than or equal to 10 years, greater than 10 years and less than or equal to 100 years, greater than 100 years and less than or equal to 1,000 years, and greater than 1,000 years; and simulated ending zones were grouped into 48 receiving water bodies, based on the New York State Department of Environmental Conservation Waterbody Inventory/Priority Waterbodies List. Areal delineation of travel time zones and groundwater contributing areas were generated and a table was prepared presenting the sum of groundwater outflow for each area.

Factors affecting re-vegetation dynamics of experimentally restored extracted peatland in Estonia.

PubMed

Karofeld, Edgar; Müür, Mari; Vellak, Kai

2016-07-01

Increasing human activity continues to threaten peatlands, and as the area of natural mires declines, our obligation is to restore their ecosystem functions. Several restoration strategies have been developed for restoration of extracted peatlands, including "The moss layer transfer method", which was initiated on the Tässi extracted peatland in central Estonia in May 2012. Three-year study shows that despite the fluctuating water table, rainfall events can compensate for the insufficient moisture for mosses. Total plant cover on the restoration area attained 70 %, of which ~60 % is comprised of target species-Sphagnum mosses. From restoration treatments, spreading of plant fragments had a significant positive effect on the cover of bryophyte and vascular plants. Higher water table combined with higher plant fragments spreading density and stripping of oxidised peat layer affected positively the cover of targeted Sphagnum species. The species composition in the restoration area became similar to that in the donor site in a natural bog. Based on results, it was concluded that the method approved for restoration in North America gives good results also in the restoration of extracted peatland towards re-establishment of bog vegetation under northern European conditions.

Water Table Depth Reconstruction in Ombrotrophic Peatlands Using Biomarker Abundance Ratios and Compound-Specific Hydrogen Isotope Composition

NASA Astrophysics Data System (ADS)

Nichols, J. E.; Jackson, S. T.; Booth, R. K.; Pendall, E. G.; Huang, Y.

2005-12-01

Sediment cores from ombrotrophic peat bogs provide sensitive records of changes in precipitation/evaporation (P/E) balance. Various proxies have been developed to reconstruct surface moisture conditions in peat bogs, including testate amoebae, plant macrofossils, and peat humification. Studying species composition of testate amoeba assemblages is time consuming and requires specialized training. Humification index can be influenced by environmental factors other than moisture balance. The plant macrofossil proxy is less quantitative and cannot be performed on highly decomposed samples. We demonstrate that the ratio of C23 alkane to C29 alkane abundance may provide a simple alternative or complementary means of tracking peatland water-table depth. Data for this proxy can be collected quickly using a small sample (100 mg dry). Water-table depth decreases during drought, and abundance of Sphagnum, the dominant peat-forming genus, decreases as vascular plants increase. Sphagnum moss produces mainly medium chain-length alkanes (C21-C25) while vascular plants (grasses and shrubs) produce primarily longer chain-length alkanes (C27-C31). Therefore, C23:C29 n-alkane ratios quantitatively track the water table depth fluctuations in peat bogs. We compared C23:C29 n-alkane ratios in a core from Minden Bog (southeastern Michigan) with water table depth reconstructions based on testate-amoeba assemblages and humification. The 184-cm core spans the past ~3kyr of continuous peat deposition in the bog. Our results indicate that the alkane ratios closely track the water table depth variations, with C29 most abundant during droughts. We also explored the use of D/H ratios in Sphagnum biomarkers as a water-table depth proxy. Compound-specific hydrogen isotope ratio analyses were performed on Sphagnum biomarkers: C23 and C25 alkane and C24 acid. Dry periods are represented in these records by an enrichment of deuterium in these Sphagnum-specific compounds. These events also correlate with drought events in the testate amoeba record and the alkane abundance ratio record. These biogeochemical proxies can be used in paleohydrological studies of ombrotrophic bogs and provide a new and complimentary source of data from these underutilized paleoclimate archives.

Comparison of specific-yield estimates for calculating evapotranspiration from diurnal groundwater-level fluctuations

NASA Astrophysics Data System (ADS)

Gribovszki, Zoltán

2018-05-01

Methods that use diurnal groundwater-level fluctuations are commonly used for shallow water-table environments to estimate evapotranspiration (ET) and recharge. The key element needed to obtain reliable estimates is the specific yield (Sy), a soil-water storage parameter that depends on unsaturated soil-moisture and water-table fluxes, among others. Soil-moisture profile measurement down to the water table, along with water-table-depth measurements, can provide a good opportunity to calculate Sy values even on a sub-daily scale. These values were compared with Sy estimates derived by traditional techniques, and it was found that slug-test-based Sy values gave the most similar results in a sandy soil environment. Therefore, slug-test methods, which are relatively cheap and require little time, were most suited to estimate Sy using diurnal fluctuations. The reason for this is that the timeframe of the slug-test measurement is very similar to the dynamic of the diurnal signal. The dynamic characteristic of Sy was also analyzed on a sub-daily scale (depending mostly on the speed of drainage from the soil profile) and a remarkable difference was found in Sy with respect to the rate of change of the water table. When comparing constant and sub-daily (dynamic) Sy values for ET estimation, the sub-daily Sy application yielded higher correlation, but only a slightly smaller deviation from the control ET method, compared with the usage of constant Sy.

Mineralogy of fine-grained alluvium from borehole U11g, expl. 1, northern Frenchman Flat area, Nevada Test Site

USGS Publications Warehouse

Jones, B.F.

1982-01-01

The mineralogy of matrix fines in alluvium from borehole Ullg, expl. 1, north of Frenchman Flat, Nevada Test Site, has been examined for evidence of past variations in water table elevation. Although greater abundance of zeolite and slightly more expanded basal spacings in smectite clays suggest effects of increased hydration of material up to 50 m above the present water table, these differences might also be related to provenance of environment of deposition. The relative uniformity of clay hydration properties in the 50 meters above the current water table suggest long-term stability near the present level. (USGS)

Simulation of hydrodynamics, temperature, and dissolved oxygen in Table Rock Lake, Missouri, 1996-1997

USGS Publications Warehouse

Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.

2003-01-01

Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.

Evaluation and analysis of current compaction methods for FDOT pipe trench backfills in areas of high water tables

DOT National Transportation Integrated Search

1999-01-01

This research project was undertaken to examine the practicality and adequacy of the FDOT specifications regarding compaction methods for pipe trench backfills under high water table. Given the difficulty to determine density and to attain desired de...

Aquifer response to stream-stage and recharge variations. I. Analytical step-response functions

USGS Publications Warehouse

Moench, A.F.; Barlow, P.M.

2000-01-01

Laplace transform step-response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic, homogeneous unconfined aquifers interacting with perennial streams. Flow is one-dimensional, perpendicular to the stream in the confined and leaky aquifers, and two-dimensional in a plane perpendicular to the stream in the water-table aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank. The solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated. The Laplace transform solutions are inverted numerically to obtain the real-time step-response functions for use in the convolution (or superposition) integral. To maintain linearity in the case of unconfined aquifers, fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness, and vertical flow into or out of the zone above the water table is assumed to occur instantaneously. Effects of hysteresis in the moisture distribution above the water table are therefore neglected. Graphical comparisons of the new solutions are made with known closed-form solutions.Laplace transform step-response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic, homogeneous unconfined aquifers interacting with perennial streams. Flow is one-dimensional, perpendicular to the stream in the confined and leaky aquifers, and two-dimensional in a plane perpendicular to the stream in the water-table aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank. The solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated. The Laplace transform solutions are inverted numerically to obtain the real-time step-response functions for use in the convolution (or superposition) integral. To maintain linearity in the case of unconfined aquifers, fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness, and vertical flow into or out of the zone above the water table is assumed to occur instantaneously. Effects of hysteresis in the moisture distribution above the water table are therefore neglected. Graphical comparisons of the new solutions are made with known closed-form solutions.

Molecular Simulations of Shear-Induced Dynamics in Nitromethane

DTIC Science & Technology

2016-09-01

initially staggered along the y axis, and then after the crystal is sheared b), the NM molecules are rotated to orient themselves in the same... rotation of the grain. ...............................................................................8 List of Tables Table 1 Summary of the maximum...it an ideal candidate to study chemical reaction mechanisms associated with conventional explosive initiation and subsequent detonation .3,6,7

40 CFR Table 5 to Subpart Zzzz of... - Initial Compliance With Emission Limitations and Operating Limitations

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 14 2012-07-01 2011-07-01 true Initial Compliance With Emission Limitations and Operating Limitations 5 Table 5 to Subpart ZZZZ of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES ...

Making the Best of a World Dominated by League Tables? New Developments in the International Ranking of Universities

ERIC Educational Resources Information Center

Observatory on Borderless Higher Education, 2010

2010-01-01

Two interesting initiatives have started to develop more balanced international league tables of universities. The first initiative is being taken by UK magazine the Times Higher Education (THE), which recently entered into a collaboration with both the international academic community and research-metrics company Thomsons Reuters to create an…

Environmental Regulatory Update Table, November--December 1993

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

Houlberg, L.M.; Hawkins, G.T.; Salk, M.S.

1994-01-01

The Environmental Regulatory Update Table provides information on regulatory of interest to DOE operations and contractor staff with environmental management responsibilities. The table is updated bi-monthly with information from the Federal Register and other sources, including direct contact with regulatory agencies. Each table entry provides a chronological record of the rulemaking process for that initiative with an abstract and a projection of further action.

A generalized groundwater fluctuation model based on precipitation for estimating water table levels of deep unconfined aquifers

NASA Astrophysics Data System (ADS)

Jeong, Jina; Park, Eungyu; Shik Han, Weon; Kim, Kue-Young; Suk, Heejun; Beom Jo, Si

2018-07-01

A generalized water table fluctuation model based on precipitation was developed using a statistical conceptualization of unsaturated infiltration fluxes. A gamma distribution function was adopted as a transfer function due to its versatility in representing recharge rates with temporally dispersed infiltration fluxes, and a Laplace transformation was used to obtain an analytical solution. To prove the general applicability of the model, convergences with previous water table fluctuation models were shown as special cases. For validation, a few hypothetical cases were developed, where the applicability of the model to a wide range of unsaturated zone conditions was confirmed. For further validation, the model was applied to water table level estimations of three monitoring wells with considerably thick unsaturated zones on Jeju Island. The results show that the developed model represented the pattern of hydrographs from the two monitoring wells fairly well. The lag times from precipitation to recharge estimated from the developed system transfer function were found to agree with those from a conventional cross-correlation analysis. The developed model has the potential to be adopted for the hydraulic characterization of both saturated and unsaturated zones by being calibrated to actual data when extraneous and exogenous causes of water table fluctuation are limited. In addition, as it provides reference estimates, the model can be adopted as a tool for surveilling groundwater resources under hydraulically stressed conditions.

Depth distribution of microbial production and oxidation of methane in northern boreal peatlands.

PubMed

Sundh, I; Nilsson, M; Granberg, G; Svensson, B H

1994-05-01

The depth distributions of anaerobic microbial methane production and potential aerobic microbial methane oxidation were assessed at several sites in both Sphagnum- and sedge-dominated boreal peatlands in Sweden, and compared with net methane emissions from the same sites. Production and oxidation of methane were measured in peat slurries, and emissions were measured with the closed-chamber technique. Over all eleven sites sampled, production was, on average, highest 12 cm below the depth of the average water table. On the other hand, highest potential oxidation of methane coincided with the depth of the average water table. The integrated production rate in the 0-60 cm interval ranged between 0.05 and 1.7 g CH4 m (-2) day(-) and was negatively correlated with the depth of the average water table (linear regression: r (2) = 0.50, P = 0.015). The depth-integrated potential CH4-oxidation rate ranged between 3.0 and 22.1 g CH4 m(-2) day(-1) and was unrelated to the depth of the average water table. A larger fraction of the methane was oxidized at sites with low average water tables; hence, our results show that low net emission rates in these environments are caused not only by lower methane production rates, but also by conditions more favorable for the development of CH4-oxidizing bacteria in these environments.

New Polish occupational health and safety regulations for underwater works.

PubMed

Kot, Jacek; Sićko, Zdzisław

2007-01-01

In Poland, the new regulation of the Ministry of Health on Occupational Health for Underwater Works (dated 2007) pursuant to the Act on Underwater Works (dated 2003) has just been published. It is dedicated for commercial, non-military purposes. It defines health requirements for commercial divers and candidates for divers, medical assessment guide with a list of specific medical tests done on initial and periodical medical examination in order for a diver or a candidate for diver to be recognised fit for work, health surveillance during diving operations, compression and decompression procedures, list of content for medical equipment to be present at any diving place, formal qualifications for physicians conducting medical assessment of divers, requirements for certifications confirming the medical status of divers and candidates for divers. Decompression tables cover divings up to 120 meters of depth using compressed air, oxygen, nitrox and heliox as breathing mixtures. There are also decompression tables for repetitive diving, altitude diving and diving in the high-density waters (mud diving). It this paper, general description of health requirements for divers, as well as decompression tables that are included in the new Regulation on Occupational Health for Underwater Works are presented.

Treatment of Chlorinated Aliphatic Contamination of Groundwater by Horizontal Recirculation Wells and by Constructed Vertical Flow Wetlands

DTIC Science & Technology

2002-03-01

groundwater laden with contaminants. Once the contaminated water is at the surface, it must be treated for contaminant destruction, generally by...treatment walls only work under very specific hydrogeologic conditions (relatively shallow water table, no seasonal fluctuations in groundwater flow...GCWs Elevation Schematic Water Table Contaminated Groundwater Contaminated Groundwater Treated Groundwater Treated Groundwater Reactive Porous Medium

Trajectories of ecosystem service change in restored peatlands

NASA Astrophysics Data System (ADS)

Evans, Martin; Shuttleworth, Emma; Pilkington, Mike; Allott, Tim; Walker, Jonathan; Spencer, Tom

2017-04-01

Peatlands provide a wide range of ecosystem services but across the world degradation of these systems through a range of human impacts has had a negative effect on the provision of these services. A wide variety of peatland restoration approaches have been developed with the aim of mitigating these impacts. Understanding of trajectories of change in ecosystem structure and function is central to evaluating the efficacy of these restoration methods. This paper considers data on post-restoration trajectories of water table change, vegetation recovery, runoff production and water quality based on extensive data from peatland restoration work in the southern Pennines of the U.K. Data have been compiled from multiple restoration initiatives undertaken across the region, spanning up to 12 years post restoration. The data show variations in the time scale of ecosystem change which are indicative of the process basis of the ecosystem trajectories. Rapid changes in runoff are controlled by physical changes to the peatland surface. These are contrasted with longer term evolution of vegetation and water table behaviour which suggest ongoing recovery as the ecosystem adjusts to the restoration process. In order to assess restoration of ecosystem function, and so of ecosystem services, it is important that the process links between ecosystem structure and function are well understood. Establishing typical restoration trajectories can be of practical use in determining restoration project milestones, and can also provide insight into the nature of these process links.

Pumping strategies for management of a shallow water table: The value of the simulation-optimization approach

USGS Publications Warehouse

Barlow, P.M.; Wagner, B.J.; Belitz, K.

1996-01-01

The simulation-optimization approach is used to identify ground-water pumping strategies for control of the shallow water table in the western San Joaquin Valley, California, where shallow ground water threatens continued agricultural productivity. The approach combines the use of ground-water flow simulation with optimization techniques to build on and refine pumping strategies identified in previous research that used flow simulation alone. Use of the combined simulation-optimization model resulted in a 20 percent reduction in the area subject to a shallow water table over that identified by use of the simulation model alone. The simulation-optimization model identifies increasingly more effective pumping strategies for control of the water table as the complexity of the problem increases; that is, as the number of subareas in which pumping is to be managed increases, the simulation-optimization model is better able to discriminate areally among subareas to determine optimal pumping locations. The simulation-optimization approach provides an improved understanding of controls on the ground-water flow system and management alternatives that can be implemented in the valley. In particular, results of the simulation-optimization model indicate that optimal pumping strategies are constrained by the existing distribution of wells between the semiconfined and confined zones of the aquifer, by the distribution of sediment types (and associated hydraulic conductivities) in the western valley, and by the historical distribution of pumping throughout the western valley.

Development and application of a groundwater/surface-water flow model using MODFLOW-NWT for the Upper Fox River Basin, southeastern Wisconsin

USGS Publications Warehouse

Feinstein, D.T.; Fienen, M.N.; Kennedy, J.L.; Buchwald, C.A.; Greenwood, M.M.

2012-01-01

The Fox River is a 199-mile-long tributary to the Illinois River within the Mississippi River Basin in the states of Wisconsin and Illinois. For the purposes of this study the Upper Fox River Basin is defined as the topographic basin that extends from the upstream boundary of the Fox River Basin to a large wetland complex in south-central Waukesha County called the Vernon Marsh. The objectives for the study are to (1) develop a baseline study of groundwater conditions and groundwater/surface-water interactions in the shallow aquifer system of the Upper Fox River Basin, (2) develop a tool for evaluating possible alternative water-supply options for communities in Waukesha County, and (3) contribute to the methodology of groundwater-flow modeling by applying the recently published U.S. Geological Survey MODFLOW-NWT computer code, (a Newton formulation of MODFLOW-2005 intended for solving difficulties involving drying and rewetting nonlinearities of the unconfined groundwater-flow equation) to overcome computational problems connected with fine-scaled simulation of shallow aquifer systems by means of thin model layers. To simulate groundwater conditions, a MODFLOW grid is constructed with thin layers and small cell dimensions (125 feet per side). This nonlinear unconfined problem incorporates the streamflow/lake (SFR/LAK) packages to represent groundwater/surface-water interactions, which yields an unstable solution sensitive to initial conditions when solved using the Picard-based preconditioned-gradient (PCG2) solver. A particular problem is the presence of many isolated wet water-table cells over dry cells, causing the simulated water table to assume unrealistically high values. Attempts to work around the problem by converting to confined conditions or converting active to inactive cells introduce unacceptable bias. Application of MODFLOW-NWT overcomes numerical problem by smoothing the transition from wet to dry cells and keeps all cells active. The simulation is insensitive to initial conditions and the water-table trend is smooth across layers. The MODFLOW-NWT code permits rigorous calibration and also robust application of the model to transient scenarios. Runtimes on a 64-bit computer are kept reasonably short by use of updated initial conditions and informed choices of solver parameters. The shallow aquifer system consists of unconsolidated material of varying thickness over Silurian dolomite. The unconsolidated material, largely of glacial origin, contains fine-textured and coarse-textured deposits that vary in permeability over short distances. This study at least partly encompasses the inevitable uncertainty in the hydraulic conductivity zones by developing two models—one favors the continuity of fine-grained deposits and a second favors the continuity of coarse-grained deposits. The separate calibration processes for the fine-favored and coarse-favored models using MODFLOW-NWT and the nonlinear regression algorithms in the parameter estimation (PEST) code produce distinct parameter values for hydraulic conductivity zones, storage parameters, and streambed conductance zones. Both models are applied to a hypothetical scenario involving 27 "riparian" wells completed adjacent to the river channel and open to the shallow aquifer systems along a 10-mile stretch of the Fox River. The results suggest that a riparian well system withdrawing about 9 million gallons per day would induce about one-third to one-half its total discharge from the river, and that this riverbank inducement would appreciably limit drawdown around the hypothetical wells.

Final report: Initial ecosystem response of salt marshes to ditch plugging and pool creation: Experiments at Rachel Carson National Wildlife Refuge (Maine)

USGS Publications Warehouse

Adamowicz, S.C.; Roman, C.T.

2002-01-01

This study evaluates the response of three salt marshes, associated with the Rachel Carson National Wildlife Refuge (Maine), to the practice of ditch plugging. Drainage ditches, originally dug to drain the marsh for mosquito control or to facilitate salt hay farming, are plugged with marsh peat in an effort to impound water upstream of the plug, raise water table levels in the marsh, and increase surface water habitat. At two study sites, Moody Marsh and Granite Point Road Marsh, ditch plugs were installed in spring 2000. Monitoring of hydrology, vegetation, nekton and bird utilization, and marsh development processes was conducted in 1999, before ditch plugging, and then in 2000 and 2001 (all parameters except nekton), after ditch plugging. Each study site had a control marsh that was monitored simultaneously with the plugged marsh, and thus, we employed a BACI study design (before, after, control, impact). A third site, Marshall Point Road Marsh, was plugged in 1998. Monitoring of the plugged and control sites was conducted in 1999 and 2000, with limited monitoring in 2001, thus there was no ?before? plug monitoring. With ditch plugging, water table levels increased toward the marsh surface and the areal extent of standing water increased. Responding to a wetter substrate, a vegetation change from high marsh species (e.g., Spartina patens) to those more tolerant of flooded conditions (e.g., Spartina alterniflora) was noted at two of the three ditch plugged sites. Initial response of the nekton community (fishes and decapod crustaceans) was evaluated by monitoring utilization of salt marsh pools using a 1m2 enclosure trap. In general, nekton species richness, density, and community structure remained unchanged following ditch plugging at the Moody and Granite Point sites. At Marshall Point, species richness and density (number of individuals per m2) were significantly greater in the experimental plugged marsh than the control marsh (<2% of the control marsh was open water habitat vs. 11% of the plugged marsh). The response of birds, categorized as waterfowl & waterbirds, shorebirds & wading birds, gulls & terns, and miscellaneous (raptors, passerines, other), was variable. Following ditch plugging, bird species richness increased at the Granite Point site (1999 pre-plug = 15.4, 2000 post-plug = 26.2, 2001 post-plug = 38.7). Because of a low sample size at Moody Marsh, reliable statements on species richness cannot be made. Density of birds (no. of birds per ha) remained unchanged with ditch plugging at Granite Point Marsh, although there was a strong, but not statistically significant, trend toward increased density. This study only reports on initial responses of marsh functions to ditch plugging. Monitoring should continue at these sites, and perhaps at additional sites, for the next decade or so. A monitoring plan is recommended. Long-term monitoring will include evaluation of salt marsh development processes using SET (surface elevation table) methodology. There is concern, although not confirmed, that as ditch-plugged marshes become wetter and marsh grass production declines their ability to keep pace with sea level rise could be jeopardized. It is suggested that ditch plugging should be considered an experimental marsh management technique. Additional monitoring on the physical and habitat responses of ditch-plugged marshes is required, along with assessments of other techniques aimed at restoring open water habitat to the marsh surface.

Geophysical Methods for Investigating Ground-Water Recharge

USGS Publications Warehouse

Ferre, Ty P.A.; Binley, Andrew M.; Blasch, Kyle W.; Callegary, James B.; Crawford, Steven M.; Fink, James B.; Flint, Alan L.; Flint, Lorraine E.; Hoffmann, John P.; Izbicki, John A.; Levitt, Marc T.; Pool, Donald R.; Scanlon, Bridget R.

2007-01-01

While numerical modeling has revolutionized our understanding of basin-scale hydrologic processes, such models rely almost exclusively on traditional measurements?rainfall, streamflow, and water-table elevations?for calibration and testing. Model calibration provides initial estimates of ground-water recharge. Calibrated models are important yet crude tools for addressing questions about the spatial and temporal distribution of recharge. An inverse approach to recharge estimation is taken of necessity, due to inherent difficulties in making direct measurements of flow across the water table. Difficulties arise because recharging fluxes are typically small, even in humid regions, and because the location of the water table changes with time. Deep water tables in arid and semiarid regions make recharge monitoring especially difficult. Nevertheless, recharge monitoring must advance in order to improve assessments of ground-water recharge. Improved characterization of basin-scale recharge is critical for informed water-resources management. Difficulties in directly measuring recharge have prompted many efforts to develop indirect methods. The mass-balance approach of estimating recharge as the residual of generally much larger terms has persisted despite the use of increasing complex and finely gridded large-scale hydrologic models. Geophysical data pertaining to recharge rates, timing, and patterns have the potential to substantially improve modeling efforts by providing information on boundary conditions, by constraining model inputs, by testing simplifying assumptions, and by identifying the spatial and temporal resolutions needed to predict recharge to a specified tolerance in space and in time. Moreover, under certain conditions, geophysical measurements can yield direct estimates of recharge rates or changes in water storage, largely eliminating the need for indirect measures of recharge. This appendix presents an overview of physically based, geophysical methods that are currently available or under development for recharge monitoring. The material is written primarily for hydrogeologists. Uses of geophysical methods for improving recharge monitoring are explored through brief discussions and case studies. The intent is to indicate how geophysical methods can be used effectively in studying recharge processes and quantifying recharge. As such, the material constructs a framework for matching the strengths of individual geophysical methods with the manners in which they can be applied for hydrologic analyses. The appendix is organized in three sections. First, the key hydrologic parameters necessary to determine the rate, timing, and patterns of recharge are identified. Second, the basic operating principals of the relevant geophysical methods are discussed. Methods are grouped by the physical property that they measure directly. Each measured property is related to one or more of the key hydrologic properties for recharge monitoring. Third, the emerging conceptual framework for applying geophysics to recharge monitoring is presented. Examples of the application of selected geophysical methods to recharge monitoring are presented in nine case studies. These studies illustrate hydrogeophysical applications under a wide range of conditions and measurement scales, which vary from tenths of a meter to hundreds of meters. The case studies include practice-proven as well as emerging applications of geophysical methods to recharge monitoring.

Bibliography, indices, and data sources of water-related studies, upper Colorado River basin, Colorado and Utah, 1872-1995

USGS Publications Warehouse

Bauch, N.J.; Apodaca, L.E.

1995-01-01

As part of the U.S. Geological Survey's National Water-Quality Assessment Program, current water-quality conditions in the Upper Colorado River Basin in Colorado and Utah are being assessed. This report is an initial effort to identify and compile information on water-related studies previously conducted in the basin and consists of a bibliography, coauthor and subject indices, and sources of available water-related data. Computerized literature searches of scientific data bases were carried out to identify past water-related studies in the basin, and government agencies and private organizations were contacted regarding their knowledge or possession of water-related publications and data. Categories of information in the bibliography include: aquatic biology, climate, energy development, geology, land use, limnology, runoff, salinity, surface- and ground-water hydrology, water chemistry, water quality and quantity, and water use and management. The approximately 1,400 indexed references date from 1872 through February 1995 and include books, journal articles, maps, and reports. In many instances, an abstract has been provided for a given reference. Sources of water-related data in the basin are included in a table.

77 FR 70991 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-28

... Monitoring System (NAHMS) will initiate the second national data collection of table egg layers through... have a role in the prevention and control of Samonella Enteritidis on table eggs farms. This working... a current estimate of the prevalence of Samonella Enteritidis on table egg farms. Need and Use of...

Combining slope stability and groundwater flow models to assess stratovolcano collapse hazard

NASA Astrophysics Data System (ADS)

Ball, J. L.; Taron, J.; Reid, M. E.; Hurwitz, S.; Finn, C.; Bedrosian, P.

2016-12-01

Flank collapses are a well-documented hazard at volcanoes. Elevated pore-fluid pressures and hydrothermal alteration are invoked as potential causes for the instability in many of these collapses. Because pore pressure is linked to water saturation and permeability of volcanic deposits, hydrothermal alteration is often suggested as a means of creating low-permeability zones in volcanoes. Here, we seek to address the question: What alteration geometries will produce elevated pore pressures in a stratovolcano, and what are the effects of these elevated pressures on slope stability? We initially use a finite element groundwater flow model (a modified version of OpenGeoSys) to simulate `generic' stratovolcano geometries that produce elevated pore pressures. We then input these results into the USGS slope-stability code Scoops3D to investigate the effects of alteration and magmatic intrusion on potential flank failure. This approach integrates geophysical data about subsurface alteration, water saturation and rock mechanical properties with data about precipitation and heat influx at Cascade stratovolcanoes. Our simulations show that it is possible to maintain high-elevation water tables in stratovolcanoes given specific ranges of edifice permeability (ideally between 10-15 and 10-16 m2). Low-permeability layers (10-17 m2, representing altered pyroclastic deposits or altered breccias) in the volcanoes can localize saturated regions close to the surface, but they may actually reduce saturation, pore pressures, and water table levels in the core of the volcano. These conditions produce universally lower factor-of-safety (F) values than at an equivalent dry edifice with the same material properties (lower values of F indicate a higher likelihood of collapse). When magmatic intrusions into the base of the cone are added, near-surface pore pressures increase and F decreases exponentially with time ( 7-8% in the first year). However, while near-surface impermeable layers create elevated water tables and pore pressures, they do not necessarily produce the largest or deepest collapses. This suggests that mechanical properties of both the edifice and layers still exert a significant control, and collapse volumes depend on a complex interplay of mechanical factors and layering.

18 CFR Table 1 to Part 301 - Functionalization and Escalation Codes

Code of Federal Regulations, 2010 CFR

2010-04-01

... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Functionalization and Escalation Codes 1 Table 1 to Part 301 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS FOR FEDERAL POWER MARKETING ADMINISTRATIONS AVERAGE SYSTEM COST...

18 CFR Table 1 to Part 301 - Functionalization and Escalation Codes

Code of Federal Regulations, 2012 CFR

2012-04-01

... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Functionalization and Escalation Codes 1 Table 1 to Part 301 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS FOR FEDERAL POWER MARKETING ADMINISTRATIONS AVERAGE SYSTEM COST...

18 CFR Table 1 to Part 301 - Functionalization and Escalation Codes

Code of Federal Regulations, 2013 CFR

2013-04-01

... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Functionalization and Escalation Codes 1 Table 1 to Part 301 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS FOR FEDERAL POWER MARKETING ADMINISTRATIONS AVERAGE SYSTEM COST...

18 CFR Table 1 to Part 301 - Functionalization and Escalation Codes

Code of Federal Regulations, 2014 CFR

2014-04-01

... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Functionalization and Escalation Codes 1 Table 1 to Part 301 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS FOR FEDERAL POWER MARKETING ADMINISTRATIONS AVERAGE SYSTEM COST...

Denitrification and gas emissions from organic soils under different water-table and flooding management

USDA-ARS?s Scientific Manuscript database

Draining the Florida Everglades for agricultural use has led to land subsidence and increase phosphorus loads to the southern Everglades, environmental concerns which can be limited by controlling water table depth. The resulting anaerobic conditions in saturated soils may lead to increased denitrif...

18 CFR Table 1 to Part 301 - Functionalization and Escalation Codes

Code of Federal Regulations, 2011 CFR

2011-04-01

... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Functionalization and Escalation Codes 1 Table 1 to Part 301 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS FOR FEDERAL POWER MARKETING ADMINISTRATIONS AVERAGE SYSTEM COST...

Controlled laboratory experiments and modeling of vegetative filter strips with shallow water tables

NASA Astrophysics Data System (ADS)

Fox, Garey A.; Muñoz-Carpena, Rafael; Purvis, Rebecca A.

2018-01-01

Natural or planted vegetation at the edge of fields or adjacent to streams, also known as vegetative filter strips (VFS), are commonly used as an environmental mitigation practice for runoff pollution and agrochemical spray drift. The VFS position in lowlands near water bodies often implies the presence of a seasonal shallow water table (WT). In spite of its potential importance, there is limited experimental work that systematically studies the effect of shallow WTs on VFS efficacy. Previous research recently coupled a new physically based algorithm describing infiltration into soils bounded by a water table into the VFS numerical overland flow and transport model, VFSMOD, to simulate VFS dynamics under shallow WT conditions. In this study, we tested the performance of the model against laboratory mesoscale data under controlled conditions. A laboratory soil box (1.0 m wide, 2.0 m long, and 0.7 m deep) was used to simulate a VFS and quantify the influence of shallow WTs on runoff. Experiments included planted Bermuda grass on repacked silt loam and sandy loam soils. A series of experiments were performed including a free drainage case (no WT) and a static shallow water table (0.3-0.4 m below ground surface). For each soil type, this research first calibrated VFSMOD to the observed outflow hydrograph for the free drainage experiments to parameterize the soil hydraulic and vegetation parameters, and then evaluated the model based on outflow hydrographs for the shallow WT experiments. This research used several statistical metrics and a new approach based on hypothesis testing of the Nash-Sutcliffe model efficiency coefficient (NSE) to evaluate model performance. The new VFSMOD routines successfully simulated the outflow hydrographs under both free drainage and shallow WT conditions. Statistical metrics considered the model performance valid with greater than 99.5% probability across all scenarios. This research also simulated the shallow water table experiments with both free drainage and various water table depths to quantify the effect of assuming the former boundary condition. For these two soil types, shallow WTs within 1.0-1.2 m below the soil surface influenced infiltration. Existing models will suggest a more protective vegetative filter strip than what actually exists if shallow water table conditions are not considered.

Using a Process Based Model to Simulate the Effects of Drainage and Land Use Change on Hydrology, and Sediment and Nutrient Transport in the Midwestern United States

NASA Astrophysics Data System (ADS)

Downer, C. W.; Pradhan, N. R.; Skahill, B. E.; Wahl, M.; Turnbull, S. J.

2015-12-01

Historically the Midwestern United State was a region dominated by prairie grasses and wetlands. To make use of the rich soils underlying these fertile environments, farmers converted the land to agriculture and currently the Midwest is a region of intensive agricultural production, with agriculture being a predominant land use. The Midwest is a region of gentle slopes, tight soils, and high water tables, and in order to make the lands suitable for agriculture, farmers have installed extensive networks of ditches to drain off excess surface water and subsurface tiles to lower the water table and remove excess soil water in the root zone that can stress common row crops, such as corn and soybeans. The combination of tiles, ditches, and intensive agricultural land practices radically alters the landscape and hydrology. As part of the Minnesota River Basin Integrated Study we are simulating nested watersheds in a sub-basin of the Minnesota River Basin, Seven Mile Creek, using the physics-based watershed model GSSHA (Gridded Surface Subsurface Hydrologic Analysis) to simulate water, sediment, and nutrients. Representative of the larger basin, more than 80% of the land in the watershed is dedicated to agricultural practices. From a process perspective, the hydrology is complicated, with snow accumulation and melt, frozen soil, and tile drains all being important processes within the watershed. In this study we attempt to explicitly simulate these processes, including the tile drains, which are simulated as a network of subsurface pipes that collect water from the local water table. Within the watershed, tiles discharge to both the ditch/stream network as well as overland locations, where the tile discharge appears to initiate gullies and exacerbate overland erosion. Testing of the methods on smaller basins demonstrates the ability of the model to simulate measured tile flow. At the larger scale, the model demonstrates ability to simulate flow and sediments. Sparse nutrient data limit the assessment of nutrient simulations. The models are being used to asses an array of potential future land use scenarios, including predevelopment and increased agricultural use. Results from these simulations will be presented. Preliminary results indicate that tile drains increase discharge and erosion in the watershed.

Impacts of ditch blocking on peatland hydrology - the benefits of long-term monitoring

NASA Astrophysics Data System (ADS)

Holden, Joseph; Green, Sophie; Baird, Andy; Chapman, Pippa; Evans, Chris; Grayson, Richard

2016-04-01

A long-term field trial was conducted on a blanket peatland in North Wales. Twelve ditches were studied. After an initial monitoring period, eight of the ditches had peat dams installed a few metres apart along their entire length (dammed), four of these ditches were also partially infilled through bank reprofiling (reprofiled). Four ditches were left open with no dams or reprofiling (open). These 12 ditches and the surrounding peat were then monitored for a further 4 years. The effect of ditch blocking on local water tables was spatially highly variable but small overall (of the order of 2-3 cm) because the site, despite having ditches, already had relatively shallow water tables (medians within the upper 10 cm of the peat profile). An initial five-fold reduction in discharge occurred in ditches that had been dammed or reprofiled. However, there was evidence of a slow change over time in ditch flow at the site in subsequent years, with the overall volume of water leaving the dammed or reprofiled ditch weirs increasing per unit of rainfall to around twice that which occurred in the first year after the restoration. These changes were not observed in the open ditches. There was therefore clear evidence of the benefits of long-term monitoring as hydrological impacts in the first year after ditch blocking were very different from those in later years as the site conditions gradually changed. The additional water that flowed in later periods of the study from the blocked ditch catchments occurred in the form of a more continuously-flowing baseflow with fewer dry periods. The cause of this increase was related to changes in subsurface flow pathways in the peat in the aftermath of re-wetting. We show that these subsurface pathways mean that even in sloping blanket peatlands, the catchment areas for peatland ditches may be very different from that expressed by surface topography alone. Therefore, peatland studies that have estimated aerially-weighted water or carbon fluxes from one or two open or blocked ditches and where such data have also been used in upscaling estimates, need to be treated with caution.

Dynamic chemistry in the perched groundwater flowing through weathered bedrock underling a steep forested hillslope, north California

NASA Astrophysics Data System (ADS)

Kim, H.; Rempe, D. M.; Bishop, J. K.; Dietrich, W.; Fung, I.; Wood, T. J.

2012-12-01

The spatial and temporal pattern of groundwater chemistry in the seasonally perched groundwater systems that develop in the weathered bedrock zone under hillslopes have rarely been documented, yet chemical evolution of water here dictates the runoff chemistry to streams in many places. Here we exploit an intensively instrumented hillslope to document water well chemistry at three wells and adjacent stream. We have been sampling groundwater at daily frequency since October 2008 on a forested hillslope, "Rivendell", at the Angelo Coast Range Reserve located at the headwaters of the Eel River, California. The site is typical of California's coastal Mediterranean climate. The groundwater samples have been collected from a depth near the boundary between the weathered and fresh bedrock at three locations along the hillslope: Well 1 (bottom of hillslope), Well 3 (mid-slope), and Well 10 (near the ridge). Bulk rainwater and throughfall samples were collected at a meadow across the hillslope and at the middle of the slope, respectively, as well. Near the ridge (Well 10), during the first significant rainstorms of 2009 (133mm/42.5hours) and 2010 (220mm/42hours), when the water table changed only 0.32m and 0.66m, respectively, the concentration of Ca, Mg, and Na started to increase rapidly compared to the dry season (e.g. 2-6 μM vs 0.02-0.2μM [Mg]/day). However, during these same storms, K concentration sharply increased to 50-60 μM and decreased to 20-30μM, synchronizing with the water table responses. Throughfalls of these storms had at least 10 fold lower Ca, Mg, and Na concentrations than the well water while they had 10 fold higher K compared to the pre-event groundwater values. When the total seasonal cumulative rainfall exceeds 600 mm, the Well 10 solute concentration was diluted nearly 3 fold (e.g. [Mg] 0.3 mM vs. 0.1 mM) and the water table was raised significantly (2-6 meters). Throughout the rainy season, Well10 retained its diluted chemistry signature and on average the water table remained elevated as subsequent rainstorms repeatedly recharged the system. Well10 solute concentration slowly increased at the end of the rainy season when the water table fell. In contrast, at the foot of the hill slope, even though the water table was responsive to each rainfall event, its water chemistry developed a strong dilution signatures only during the intense rainstorms (total rainfall > 70mm); the solute concentration decreased (e.g. [Mg] = 0.1mM) during the rising limb of the well hydrograph and recovered back to its pre-event value (e.g. [Mg] = 0.3mM) during the falling limb of the well hydrograph. During small storms, the solute concentration of Well 1 either did not change or slightly increased. Mid-slope showed similar behavior to Well 1. The Well 3 solute concentration was diluted about 3 fold (e.g. [Mg] 0.3mM to 0.1mM) as the water table rose and increased as the water table receded. However unlike Well 1, the water chemistry of Well 3 did not recover to its pre-event composition at any point during the rainy season and the recovery rate was slower than that of Well 1. These water chemistry observations provide insight into the dynamics of water movement within the fractured, weathered bedrock zone, and point to both vertical and lateral mixing processes that influence the chemical evolution of waters.

Biomass production, forage quality, and cation uptake of Quail bush, four-wing saltbush, and seaside barley irrigated with moderately saline-sodic water

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

Bauder, J.W.; Browning, L.S.; Phelps, S.D.

2008-07-01

The study reported here investigated capacity of Atriplex lentiformis (Torr.) S. Wats. (Quail bush), Atriplex X aptera A. Nels. (pro sp.) (Wytana four-wing saltbush), and Hordeum marinum Huds. (seaside barley) to produce biomass and crude protein and take up cations when irrigated with moderately saline-sodic water, in the presence of a shallow water table. Water tables were established at 0.38, 0.76, and 1.14m below the surface in sand-filled columns. The columns were then planted to the study species. Study plants were irrigated for 224 days; irrigation water was supplied every 7 days equal to water lost to evapotranspiration (ET) plusmore » 100mL (the volume of water removed in the most previous soil solution sampling). Water representing one of two irrigation sources was used: Powder River (PR) or coalbed natural gas (CBNG) wastewater. Biomass production did not differ significantly between water quality treatments but did differ significantly among species and water table depth within species. Averaged across water quality treatments, Hordeum marinum produced 79% more biomass than A. lentiformis and 122% more biomass than Atriplex X aptera, but contained only 11% crude protein compared to 16% crude protein in A. lentiformis and 14% crude protein in Atriplex X aptera. Atriplex spp. grown in columns with the water table at 0.38m depth produced more biomass, took up less calcium on a percentage basis, and took up more sodium on a percentage basis than when grown with the water table at a deeper depth. Uptake of cations by Atriplex lentiformis was approximately twice the uptake of cations by Atriplex X aptera and three times that of H. marinum. After 224 days of irrigation, crop growth, and cation uptake, followed by biomass harvest, EC and SAR of shallow groundwater in columns planted to A. lentiformis were less than EC and SAR of shallow ground water in columns planted to either of the other species.« less

Dynamics of flood water infiltration and ground water recharge in hyperarid desert.

PubMed

Dahan, Ofer; Tatarsky, Boaz; Enzel, Yehouda; Kulls, Christoph; Seely, Mary; Benito, Gererdo

2008-01-01

A study on flood water infiltration and ground water recharge of a shallow alluvial aquifer was conducted in the hyperarid section of the Kuiseb River, Namibia. The study site was selected to represent a typical desert ephemeral river. An instrumental setup allowed, for the first time, continuous monitoring of infiltration during a flood event through the channel bed and the entire vadose zone. The monitoring system included flexible time domain reflectometry probes that were designed to measure the temporal variation in vadose zone water content and instruments to concurrently measure the levels of flood and ground water. A sequence of five individual floods was monitored during the rainy season in early summer 2006. These newly generated data served to elucidate the dynamics of flood water infiltration. Each flood initiated an infiltration event which was expressed in wetting of the vadose zone followed by a measurable rise in the water table. The data enabled a direct calculation of the infiltration fluxes by various independent methods. The floods varied in their stages, peaks, and initial water contents. However, all floods produced very similar flux rates, suggesting that the recharge rates are less affected by the flood stages but rather controlled by flow duration and available aquifer storage under it. Large floods flood the stream channel terraces and promote the larger transmission losses. These, however, make only a negligible contribution to the recharge of the ground water. It is the flood duration within the active streambed, which may increase with flood magnitude that is important to the recharge process.

50 CFR Table 1e to Part 660... - Whiting and non-whiting initial issuance allocation percentage for IFQ decided through the...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Whiting and non-whiting initial issuance allocation percentage for IFQ decided through the harvest specifications, 2011 1e Table 1e to Part 660, Subpart C Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC...

Geohydrologic framework of the Roswell ground-water basin, Chaves and Eddy Counties, New Mexico

USGS Publications Warehouse

Welder, G.E.

1983-01-01

This report describes the geohydrology of the Roswell ground-water basin and shows the long-term hydrostatic-head changes in the aquifers. The Roswell ground-water basin consists of a carbonate artesian aquifer overlain by a leaky confining bed, which, in turn is overlain by an alluvial water-table aquifer. The water-table aquifer is hydraulically connected to the Pecos River. Ground-water pumpage from about 1,500 wells in the basin was about 378,000 acre-feet in 1978. Irrigation use on about 122,000 acres accounted for 95 percent of that pumpage.

Water resources of Washington Parish, Louisiana

USGS Publications Warehouse

White, Vincent E.; Prakken, Lawrence B.

2016-06-13

In 2010, about 34.55 million gallons per day (Mgal/d) of water were withdrawn in Washington Parish, including about 28.10 Mgal/d from groundwater sources and 6.44 Mgal/d from surface-water sources1 (table 1). Withdrawals for industrial use accounted for about 52 percent (17.80 Mgal/d) of the total water withdrawn (table 2). Other categories of use included public supply, rural domestic, irrigation, and livestock. Water-use data collected at 5-year intervals from 1960 to 2010 (fig. 2) indicated that water withdrawals peaked in 1975 at about 51.9 Mgal/d.

Modelling stream aquifer seepage in an alluvial aquifer: an improved loosing-stream package for MODFLOW

NASA Astrophysics Data System (ADS)

Osman, Yassin Z.; Bruen, Michael P.

2002-07-01

Seepage from a stream, which partially penetrates an unconfined alluvial aquifer, is studied for the case when the water table falls below the streambed level. Inadequacies are identified in current modelling approaches to this situation. A simple and improved method of incorporating such seepage into groundwater models is presented. This considers the effect on seepage flow of suction in the unsaturated part of the aquifer below a disconnected stream and allows for the variation of seepage with water table fluctuations. The suggested technique is incorporated into the saturated code MODFLOW and is tested by comparing its predictions with those of a widely used variably saturated model, SWMS_2D simulating water flow and solute transport in two-dimensional variably saturated media. Comparisons are made of both seepage flows and local mounding of the water table. The suggested technique compares very well with the results of variably saturated model simulations. Most currently used approaches are shown to underestimate the seepage and associated local water table mounding, sometimes substantially. The proposed method is simple, easy to implement and requires only a small amount of additional data about the aquifer hydraulic properties.

Preliminary Water-Table Map and Water-Quality Data for Part of the Matanuska-Susitna Valley, Alaska, 2005

USGS Publications Warehouse

Moran, Edward H.; Solin, Gary L.

2006-01-01

The Matanuska-Susitna Valley is in the northeastern part of the Cook Inlet Basin, Alaska, an area experiencing rapid population growth and development proximal to many lakes. Here water commonly flows between lakes and ground water, indicating interrelation between water quantity and quality. Thus concerns exist that poorer quality ground water may degrade local lake ecosystems. This concern has led to water-quality sampling in cooperation with the Alaska Department of Environmental Conservation and the Matanuska-Susitna Borough. A map showing the estimated altitude of the water table illustrates potential ground-water flow directions and areas where ground- and surface-water exchanges and interactions might occur. Water quality measured in selected wells and lakes indicates some differences between ground water and surface water. 'The temporal and spatial scarcity of ground-water-level and water-quality data limits the analysis of flow direction and water quality. Regionally, the water-table map indicates that ground water in the eastern and southern parts of the study area flows southerly. In the northcentral area, ground water flows predominately westerly then southerly. Although ground and surface water in most areas of the Matanuska-Susitna Valley are interconnected, they are chemically different. Analyses of the few water-quality samples collected in the area indicate that dissolved nitrite plus nitrate and orthophosphorus concentrations are higher in ground water than in surface water.'

Effects of unsaturated zone on ground-water mounding

USGS Publications Warehouse

Sumner, D.M.; Rolston, D.E.; Marino, M.A.

1999-01-01

The design of infiltration basins used to dispose of treated wastewater or for aquifer recharge often requires estimation of ground-water mounding beneath the basin. However, the effect that the unsaturated zone has on water-table response to basin infiltration often has been overlooked in this estimation. A comparison was made between two methods used to estimate ground-water mounding-an analytical approach that is limited to the saturated zone and a numerical approach that incorporates both the saturated and the unsaturated zones. Results indicate that the error that is introduced by a method that ignores the effects of the unsaturated zone on ground-water mounding increases as the basin-loading period is shortened; as the depth to the water table increases, with increasing subsurface anisotropy; and with the inclusion of fine-textured strata. Additionally, such a method cannot accommodate the dynamic nature of basin infiltration, the finite transmission time of the infiltration front to the water table, or the interception of the basin floor by the capillary fringe.The design of infiltration basins used to dispose of treated wastewater or for aquifer recharge often requires estimation of ground-water mounding beneath the basin. However, the effect that the unsaturated zone has on water-table response to basin infiltration often has been overlooked in this estimation. A comparison was made between two methods used to estimate ground-water mounding - an analytical approach that is limited to the saturated zone and a numerical approach that incorporates both the saturated and the unsaturated zones. Results indicate that the error that is introduced by a method that ignores the effects of the unsaturated zone on ground-water mounding increases as the basin-loading period is shortened; as the depth to the water table increases, with increasing subsurface anisotropy; and with the inclusion of fine-textured strata. Additionally, such a method cannot accommodate the dynamic nature of basin infiltration, the finite transmission time of the infiltration front to the water, or the interception of the basin floor by the capillary fringe.

40 CFR Table 3 to Subpart Ooo of... - Fugitive Emission Limits

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Fugitive Emission Limits 3 Table 3 to... Mineral Processing Plants Pt. 60, Subpt. OOO, Table 3 Table 3 to Subpart OOO of Part 60—Fugitive Emission...; andPeriodic inspections of water sprays according to § 60.674(b) and § 60.676(b); and A repeat...

40 CFR Table 3 to Subpart Ooo of... - Fugitive Emission Limits

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Fugitive Emission Limits 3 Table 3 to... Mineral Processing Plants Pt. 60, Subpt. OOO, Table 3 Table 3 to Subpart OOO of Part 60—Fugitive Emission...; andPeriodic inspections of water sprays according to § 60.674(b) and § 60.676(b); and A repeat...

40 CFR Table 2 to Subpart II of... - Volatile Organic HAP (VOHAP) Limits for Marine Coatings

Code of Federal Regulations, 2013 CFR

2013-07-01

... for Marine Coatings 2 Table 2 to Subpart II of Part 63 Protection of Environment ENVIRONMENTAL... (Surface Coating) Pt. 63, Subpt. II, Table 2 Table 2 to Subpart II of Part 63—Volatile Organic HAP (VOHAP) Limits for Marine Coatings Coating category VOHAP limits a,b,c Grams/liter coating (minus water and...

40 CFR Table 2 to Subpart II of... - Volatile Organic HAP (VOHAP) Limits for Marine Coatings

Code of Federal Regulations, 2012 CFR

2012-07-01

... for Marine Coatings 2 Table 2 to Subpart II of Part 63 Protection of Environment ENVIRONMENTAL... (Surface Coating) Pt. 63, Subpt. II, Table 2 Table 2 to Subpart II of Part 63—Volatile Organic HAP (VOHAP) Limits for Marine Coatings Coating category VOHAP limits a,b,c Grams/liter coating (minus water and...

40 CFR Table 2 to Subpart II of... - Volatile Organic HAP (VOHAP) Limits for Marine Coatings

Code of Federal Regulations, 2014 CFR

2014-07-01

... for Marine Coatings 2 Table 2 to Subpart II of Part 63 Protection of Environment ENVIRONMENTAL... (Surface Coating) Pt. 63, Subpt. II, Table 2 Table 2 to Subpart II of Part 63—Volatile Organic HAP (VOHAP) Limits for Marine Coatings Coating category VOHAP limits a b c Grams/liter coating (minus water and...

40 CFR Table 2 to Subpart II of... - Volatile Organic HAP (VOHAP) Limits for Marine Coatings

Code of Federal Regulations, 2010 CFR

2010-07-01

... for Marine Coatings 2 Table 2 to Subpart II of Part 63 Protection of Environment ENVIRONMENTAL... (Surface Coating) Pt. 63, Subpt. II, Table 2 Table 2 to Subpart II of Part 63—Volatile Organic HAP (VOHAP) Limits for Marine Coatings Coating category VOHAP limits a,b,c Grams/liter coating (minus water and...

40 CFR Table 2 to Subpart II of... - Volatile Organic HAP (VOHAP) Limits for Marine Coatings

Code of Federal Regulations, 2011 CFR

2011-07-01

... for Marine Coatings 2 Table 2 to Subpart II of Part 63 Protection of Environment ENVIRONMENTAL... (Surface Coating) Pt. 63, Subpt. II, Table 2 Table 2 to Subpart II of Part 63—Volatile Organic HAP (VOHAP) Limits for Marine Coatings Coating category VOHAP limits a,b,c Grams/liter coating (minus water and...

Use of geospatial technology for delineating groundwater potential zones with an emphasis on water-table analysis in Dwarka River basin, Birbhum, India

NASA Astrophysics Data System (ADS)

Thapa, Raju; Gupta, Srimanta; Gupta, Arindam; Reddy, D. V.; Kaur, Harjeet

2018-05-01

Dwarka River basin in Birbhum, West Bengal (India), is an agriculture-dominated area where groundwater plays a crucial role. The basin experiences seasonal water stress conditions with a scarcity of surface water. In the presented study, delineation of groundwater potential zones (GWPZs) is carried out using a geospatial multi-influencing factor technique. Geology, geomorphology, soil type, land use/land cover, rainfall, lineament and fault density, drainage density, slope, and elevation of the study area were considered for the delineation of GWPZs in the study area. About 9.3, 71.9 and 18.8% of the study area falls within good, moderate and poor groundwater potential zones, respectively. The potential groundwater yield data corroborate the outcome of the model, with maximum yield in the older floodplain and minimum yield in the hard-rock terrains in the western and south-western regions. Validation of the GWPZs using the yield of 148 wells shows very high accuracy of the model prediction, i.e., 89.1% on superimposition and 85.1 and 81.3% on success and prediction rates, respectively. Measurement of the seasonal water-table fluctuation with a multiplicative model of time series for predicting the short-term trend of the water table, followed by chi-square analysis between the predicted and observed water-table depth, indicates a trend of falling groundwater levels, with a 5% level of significance and a p-value of 0.233. The rainfall pattern for the last 3 years of the study shows a moderately positive correlation ( R 2 = 0.308) with the average water-table depth in the study area.

An efficient and guaranteed stable numerical method for continuous modeling of infiltration and redistribution with a shallow dynamic water table

NASA Astrophysics Data System (ADS)

Lai, Wencong; Ogden, Fred L.; Steinke, Robert C.; Talbot, Cary A.

2015-03-01

We have developed a one-dimensional numerical method to simulate infiltration and redistribution in the presence of a shallow dynamic water table. This method builds upon the Green-Ampt infiltration with Redistribution (GAR) model and incorporates features from the Talbot-Ogden (T-O) infiltration and redistribution method in a discretized moisture content domain. The redistribution scheme is more physically meaningful than the capillary weighted redistribution scheme in the T-O method. Groundwater dynamics are considered in this new method instead of hydrostatic groundwater front. It is also computationally more efficient than the T-O method. Motion of water in the vadose zone due to infiltration, redistribution, and interactions with capillary groundwater are described by ordinary differential equations. Numerical solutions to these equations are computationally less expensive than solutions of the highly nonlinear Richards' (1931) partial differential equation. We present results from numerical tests on 11 soil types using multiple rain pulses with different boundary conditions, with and without a shallow water table and compare against the numerical solution of Richards' equation (RE). Results from the new method are in satisfactory agreement with RE solutions in term of ponding time, deponding time, infiltration rate, and cumulative infiltrated depth. The new method, which we call "GARTO" can be used as an alternative to the RE for 1-D coupled surface and groundwater models in general situations with homogeneous soils with dynamic water table. The GARTO method represents a significant advance in simulating groundwater surface water interactions because it very closely matches the RE solution while being computationally efficient, with guaranteed mass conservation, and no stability limitations that can affect RE solvers in the case of a near-surface water table.

Water Table Uncertainties due to Uncertainties in Structure and Properties of an Unconfined Aquifer.

PubMed

Hauser, Juerg; Wellmann, Florian; Trefry, Mike

2018-03-01

We consider two sources of geology-related uncertainty in making predictions of the steady-state water table elevation for an unconfined aquifer. That is the uncertainty in the depth to base of the aquifer and in the hydraulic conductivity distribution within the aquifer. Stochastic approaches to hydrological modeling commonly use geostatistical techniques to account for hydraulic conductivity uncertainty within the aquifer. In the absence of well data allowing derivation of a relationship between geophysical and hydrological parameters, the use of geophysical data is often limited to constraining the structural boundaries. If we recover the base of an unconfined aquifer from an analysis of geophysical data, then the associated uncertainties are a consequence of the geophysical inversion process. In this study, we illustrate this by quantifying water table uncertainties for the unconfined aquifer formed by the paleochannel network around the Kintyre Uranium deposit in Western Australia. The focus of the Bayesian parametric bootstrap approach employed for the inversion of the available airborne electromagnetic data is the recovery of the base of the paleochannel network and the associated uncertainties. This allows us to then quantify the associated influences on the water table in a conceptualized groundwater usage scenario and compare the resulting uncertainties with uncertainties due to an uncertain hydraulic conductivity distribution within the aquifer. Our modeling shows that neither uncertainties in the depth to the base of the aquifer nor hydraulic conductivity uncertainties alone can capture the patterns of uncertainty in the water table that emerge when the two are combined. © 2017, National Ground Water Association.

Factors influencing CO2 and CH4 emissions from coastal wetlands in the Liaohe Delta, Northeast China

NASA Astrophysics Data System (ADS)

Olsson, L.; Ye, S.; Yu, X.; Wei, M.; Krauss, K. W.; Brix, H.

2015-08-01

Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, Northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2-6.1 g CH4 m-2 yr-1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2. The main controlling factors for the CH4 emissions were water table, temperature, soil organic carbon and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1 mg CH4 m-2 h-1) at soil temperatures < 18 °C. At salinity levels > 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m-2 h-1) probably because methanogens were out-competed by sulphate-reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.

Factors influencing CO2 and CH4 emissions from coastal wetlands in the Liaohe Delta, Northeast China

NASA Astrophysics Data System (ADS)

Olsson, L.; Ye, S.; Yu, X.; Wei, M.; Krauss, K. W.; Brix, H.

2015-02-01

Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2-6.1 g CH4 m-2 y-1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2. The main controlling factors for the CH4 emissions were water table, temperature and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1 mg CH4 m-2 h) at soil temperatures <18 °C. At salinity levels > 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m-2 h-1) probably because methanogens were outcompeted by sulphate reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.

The role of groundwater in hydrological processes and memory

NASA Astrophysics Data System (ADS)

Lo, Min-Hui

The interactions between soil moisture and groundwater play important roles in controlling Earth's climate, by changing the terrestrial water cycle. However, most contemporary land surface models (LSMs) used for climate modeling lack any representation of groundwater aquifers. In this dissertation, the effects of water table dynamics on the National Center for Atmospheric Research (NCAR) Community Land Model (CLM) and Community Atmosphere Model (CAM) hydrology and land-atmosphere simulations are investigated. First, a simple, lumped unconfined aquifer model is incorporated into the CLM, in which the water table is interactively coupled to the soil moisture through groundwater recharge fluxes. The recent availability of GRACE water storage data provides a unique opportunity to constrain LSMs simulations of terrestrial hydrology. A multi-objective calibration framework using GRACE and streamflow data is developed. This approach improves parameter estimation and reduces the uncertainty of water table simulations in the CLM. Next, experiments are conducted with the off-line CLM to explore the effects of groundwater on land surface memory. Results show that feedbacks of groundwater on land surface memory can be positive, negative, or neutral depending on water table dynamics. The CAM-CLM is further utilized to investigate the effects of water table dynamics on spatial-temporal variations of precipitation. Results indicate that groundwater can increase short-term (seasonal) and long-term (interannual) memory of precipitation for some regions with suitable groundwater table depth. Finally, lower tropospheric water vapor is increased due to the presence of groundwater in the model. However, the impact of groundwater on the spatial distribution of precipitation is not globally homogeneous. In the boreal summer, tropical land regions show a positive (negative) anomaly over the Northern (Southern) Hemisphere. The increased tropical precipitation follows the climatology of the convective zone rather than that of evapotranspiration. In contrast, evapotranspiration is the major contribution to the increased precipitation in the transition climatic zone (e.g., Central North America), where the land and atmosphere are strongly coupled. This dissertation reveals the highly nonlinear responses of precipitation and soil moisture to the groundwater representation in the model, and also underscores the importance of subsurface hydrological memory processes in the climate system.

Chemical character of ground water in the shallow water-table aquifer at selected localities in the Memphis area, Tennessee

USGS Publications Warehouse

Parks, William Scott; Graham, D.D.; Lowery, J.F.

1981-01-01

Eight deep wells are being monitored in the Memphis, Tenn., area to detect any changes in the chemical character of water moving through the Memphis Sand towards major pumping centers. These wells are strategically located so as to intercept groundwater enroute through the Memphis Sand from the outcrop-recharge area. Although water quality analyses are available for many wells in the shallow water-table aquifer, no specific investigation has been made to characterize the quality of the water in this aquifer from which the Memphis Sand also receives part of its recharge. This investigation is to determine the chemical character of groundwater in the shallow water-table aquifer at selected localities in the Memphis area. Methods used to install eight shallow wells at abandoned dump sites containing chemical and/or industrial waste are described. Water samples from the eight shallow wells and two deep wells in the Memphis Sand were collected and analyzed. Results of the analysis are presented and the locations of the wells and dumps are shown on maps. (USGS)

Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints

DOE PAGES

Johnson, Tim; Versteeg, Roelof; Thomle, Jon; ...

2015-08-01

Our paper describes and demonstrates two methods of providing a priori information to the surface-based time-lapse three-dimensional electrical resistivity tomography (ERT) problem for monitoring stage-driven or tide-driven surface water intrusion into aquifers. First, a mesh boundary is implemented that conforms to the known location of the water table through time, thereby enabling the inversion to place a sharp bulk conductivity contrast at that boundary without penalty. Moreover, a nonlinear inequality constraint is used to allow only positive or negative transient changes in EC to occur within the saturated zone, dependent on the relative contrast in fluid electrical conductivity between surfacemore » water and groundwater. A 3-D field experiment demonstrates that time-lapse imaging results using traditional smoothness constraints are unable to delineate river water intrusion. The water table and inequality constraints provide the inversion with the additional information necessary to resolve the spatial extent of river water intrusion through time.« less

Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints

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

Johnson, Tim; Versteeg, Roelof; Thomle, Jon

Our paper describes and demonstrates two methods of providing a priori information to the surface-based time-lapse three-dimensional electrical resistivity tomography (ERT) problem for monitoring stage-driven or tide-driven surface water intrusion into aquifers. First, a mesh boundary is implemented that conforms to the known location of the water table through time, thereby enabling the inversion to place a sharp bulk conductivity contrast at that boundary without penalty. Moreover, a nonlinear inequality constraint is used to allow only positive or negative transient changes in EC to occur within the saturated zone, dependent on the relative contrast in fluid electrical conductivity between surfacemore » water and groundwater. A 3-D field experiment demonstrates that time-lapse imaging results using traditional smoothness constraints are unable to delineate river water intrusion. The water table and inequality constraints provide the inversion with the additional information necessary to resolve the spatial extent of river water intrusion through time.« less

A comparison of northern and southern table mountain pine stands

Treesearch

Patrick H. Brose; Thomas A. Waldrop; Helen H. Mohr

2010-01-01

Table Mountain pine (Pinus pungens) stands occur throughout the Appalachian Mountains, but ecological research has concentrated on the southern part of this region. In 2006, research was initiated in northern Table Mountain pine stands growing in PA to compare some basic attributes of those stands with previously described ones in TN. Overall, the...

40 CFR Table 5 to Subpart Dddd of... - Performance Testing and Initial Compliance Demonstrations for the Compliance Options and...

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Process unit listed in Table 1B to this subpart Reduce emissions of total HAP, measured as THC, by 90... listed in Table 1B to this subpart Limit emissions of total HAP, measured as THC, to 20 ppmvd The average...

40 CFR Table 5 to Subpart Dddd of... - Performance Testing and Initial Compliance Demonstrations for the Compliance Options and...

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Process unit listed in Table 1B to this subpart Reduce emissions of total HAP, measured as THC, by 90... listed in Table 1B to this subpart Limit emissions of total HAP, measured as THC, to 20 ppmvd The average...

40 CFR Table 5 to Subpart Dddd of... - Performance Testing and Initial Compliance Demonstrations for the Compliance Options and...

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Process unit listed in Table 1B to this subpart Reduce emissions of total HAP, measured as THC, by 90... listed in Table 1B to this subpart Limit emissions of total HAP, measured as THC, to 20 ppmvd The average...

Selected techniques for monitoring water movement through unsaturated alluvium during managed aquifer recharge

USGS Publications Warehouse

Nawikas, Joseph M.; O'Leary, David R.; Izbicki, John A.; Burgess, Matthew K.

2016-10-21

Managed aquifer recharge is used to augment natural recharge to aquifers. It can be used to replenish aquifers depleted by pumping or to store water during wetter years for withdrawal during drier years. Infiltration from ponds is a commonly used, inexpensive approach for managed aquifer recharge.At some managed aquifer-recharge sites, the time when infiltrated water arrives at the water table is not always clearly shown by water-level data. As part of site characterization and operation, it can be desirable to track downward movement of infiltrated water through the unsaturated zone to identify when it arrives at the water table.

30 CFR 75.501-1 - Coal seams above the water table.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Coal seams above the water table. 75.501-1 Section 75.501-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501...

30 CFR 75.501 - Permissible electric face equipment; coal seams above water table.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Permissible electric face equipment; coal seams..., DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501 Permissible electric face equipment; coal seams above water table. [Statutory...

30 CFR 75.501-1 - Coal seams above the water table.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Coal seams above the water table. 75.501-1 Section 75.501-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501...

30 CFR 75.501-1 - Coal seams above the water table.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Coal seams above the water table. 75.501-1 Section 75.501-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501...

30 CFR 75.501-1 - Coal seams above the water table.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Coal seams above the water table. 75.501-1 Section 75.501-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501...

30 CFR 75.501 - Permissible electric face equipment; coal seams above water table.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Permissible electric face equipment; coal seams..., DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501 Permissible electric face equipment; coal seams above water table. [Statutory...

30 CFR 75.501-1 - Coal seams above the water table.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Coal seams above the water table. 75.501-1 Section 75.501-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501...

30 CFR 75.501 - Permissible electric face equipment; coal seams above water table.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Permissible electric face equipment; coal seams..., DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501 Permissible electric face equipment; coal seams above water table. [Statutory...

30 CFR 75.501 - Permissible electric face equipment; coal seams above water table.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Permissible electric face equipment; coal seams..., DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Electrical Equipment-General § 75.501 Permissible electric face equipment; coal seams above water table. [Statutory...

Sugarcane Responses to Water-Table Depth and Periodic Flood

USDA-ARS?s Scientific Manuscript database

Sugarcane (Saccharum spp.) is routinely exposed to periodic floods and shallow water tables in Florida’s Everglades Agricultural Area (EAA). The purpose of this study was to examine the yields and juice quality of four sugarcane cultivars (CP 88-1762, CP 89-2143, CP 89-2376, and CP 96-1252) maintain...

30 CFR 75.501 - Permissible electric face equipment; coal seams above water table.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Permissible electric face equipment; coal seams... Equipment-General § 75.501 Permissible electric face equipment; coal seams above water table. [Statutory Provision] On and after March 30, 1974, all electric face equipment, other than equipment referred to in...

29 CFR 1910.110 - Storage and handling of liquefied petroleum gases.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (i) Containers used with systems embodied in paragraphs (d), (e), (g), and (h) of this section... unit of weight for containers with a water capacity of 300 pounds or less. (h) With marking indicating... Table H-23. Table H-23 Water capacity per container Minimum distances Containers Underground Aboveground...

29 CFR 1910.110 - Storage and handling of liquefied petroleum gases.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (i) Containers used with systems embodied in paragraphs (d), (e), (g), and (h) of this section... unit of weight for containers with a water capacity of 300 pounds or less. (h) With marking indicating... Table H-23. Table H-23 Water capacity per container Minimum distances Containers Underground Aboveground...

Effects of nearshore recharge on groundwater interactions with a lake in mantled karst terrain

USGS Publications Warehouse

Lee, Terrie M.

2000-01-01

The recharge and discharge of groundwater were investigated for a lake basin in the mantled karst terrain of central Florida to determine the relative importance of transient groundwater inflow to the lake water budget. Variably saturated groundwater flow modeling simulated water table responses observed beneath two hillsides radiating outward from the groundwater flow‐through lake. Modeling results indicated that transient water table mounding and groundwater flow reversals in the nearshore region following large daily rainfall events generated most of the net groundwater inflow to the lake. Simulated daily groundwater inflow was greatest following water table mounding near the lake, not following subsequent peaks in the water level of upper basin wells. Transient mounding generated net groundwater inflow to the lake, that is, groundwater inflow in excess of the outflow occurring through the deeper lake bottom. The timing of the modeled net groundwater inflow agreed with an independent lake water budget; however, the quantity was considerably less than the budget‐derived value.

Physiological and morphological response patterns of Populus deltoides to alluvial groundwater

USGS Publications Warehouse

Cooper, D.J.; D'Amico, D.R.; Scott, M.L.

2003-01-01

We examined the physiological and morphological response patterns of plains cottonwood [Populus deltoides subsp. monilifera (Aiton) Eck.] to acute water stress imposed by groundwater pumping. Between 3 and 27 July 1996, four large pumps were used to withdraw alluvial groundwater from a cottonwood forest along the South Platte River, near Denver, Colorado, USA. The study was designed as a stand-level, split-plot experiment with factorial treatments including two soil types (a gravel soil and a loam topsoil over gravel), two water table drawdown depths (∼0.5 m and >1.0 m), and one water table control (no drawdown) per soil type. Measurements of water table depth, soil water potential (Ψs), predawn and midday shoot water potential (Ψpd and Ψmd), and D/H (deuterium/hydrogen) ratios of different water sources were made in each of six 600-m2 plots prior to, during, and immediately following pumping. Two additional plots were established and measured to examine the extent to which surface irrigation could be used to mitigate the effects of deep drawdown on P. deltoides for each soil type. Recovery of tree water status following pumping was evaluated by measuring stomatal conductance (gs) and xylem water potential (Ψxp) on approximately hourly time steps from before dawn to mid-afternoon on 11 August 1996 in watered and unwatered, deep-drawdown plots on gravel soils. P. deltoides responded to abrupt alluvial water table decline with decreased shoot water potential followed by leaf mortality. Ψpd and percent leaf loss were significantly related to the magnitude of water table declines. The onset and course of these responses were influenced by short-term variability in surface and ground water levels, acting in concert with physiological and morphological adjustments. Decreases in Ψpd corresponded with increases in Ψmd, suggesting shoot water status improved in response to stomatal closure and crown dieback. Crown dieback caused by xylem cavitation likely occurred when Ψpd reached −0.4 to −0.8 MPa. The application of surface irrigation allowed trees to maintain favorable water status with little or no apparent cavitation, even in deep-drawdown plots. Two weeks after the partial canopy dieback and cessation of pumping, gs and Ψxp measurements indicated that water stress persisted in unwatered P. deltoides in deep-drawdown plots.

River stage influences on uranium transport in a hydrologically dynamic groundwater-surface water transition zone

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

Zachara, John M.; Chen, Xingyuan; Murray, Chris

In this study, a well-field within a uranium (U) plume in the groundwater-surface water transition zone was monitored for a 3 year period for water table elevation and dissolved solutes. The plume discharges to the Columbia River, which displays a dramatic spring stage surge resulting from snowmelt. Groundwater exhibits a low hydrologic gradient and chemical differences with river water. River water intrudes the site in spring. Specific aims were to assess the impacts of river intrusion on dissolved uranium (U aq), specific conductance (SpC), and other solutes, and to discriminate between transport, geochemical, and source term heterogeneity effects. Time seriesmore » trends for U aq and SpC were complex and displayed large temporal and well-to-well variability as a result of water table elevation fluctuations, river water intrusion, and changes in groundwater flow directions. The wells were clustered into subsets exhibiting common behaviors resulting from the intrusion dynamics of river water and the location of source terms. Hot-spots in U aq varied in location with increasing water table elevation through the combined effects of advection and source term location. Heuristic reactive transport modeling with PFLOTRAN demonstrated that mobilized U aq was transported between wells and source terms in complex trajectories, and was diluted as river water entered and exited the groundwater system. While U aq time-series concentration trends varied significantly from year-to-year as a result of climate-caused differences in the spring hydrograph, common and partly predictable response patterns were observed that were driven by water table elevation, and the extent and duration of river water intrusion.« less

River stage influences on uranium transport in a hydrologically dynamic groundwater-surface water transition zone

DOE PAGES

Zachara, John M.; Chen, Xingyuan; Murray, Chris; ...

2016-03-04

In this study, a well-field within a uranium (U) plume in the groundwater-surface water transition zone was monitored for a 3 year period for water table elevation and dissolved solutes. The plume discharges to the Columbia River, which displays a dramatic spring stage surge resulting from snowmelt. Groundwater exhibits a low hydrologic gradient and chemical differences with river water. River water intrudes the site in spring. Specific aims were to assess the impacts of river intrusion on dissolved uranium (U aq), specific conductance (SpC), and other solutes, and to discriminate between transport, geochemical, and source term heterogeneity effects. Time seriesmore » trends for U aq and SpC were complex and displayed large temporal and well-to-well variability as a result of water table elevation fluctuations, river water intrusion, and changes in groundwater flow directions. The wells were clustered into subsets exhibiting common behaviors resulting from the intrusion dynamics of river water and the location of source terms. Hot-spots in U aq varied in location with increasing water table elevation through the combined effects of advection and source term location. Heuristic reactive transport modeling with PFLOTRAN demonstrated that mobilized U aq was transported between wells and source terms in complex trajectories, and was diluted as river water entered and exited the groundwater system. While U aq time-series concentration trends varied significantly from year-to-year as a result of climate-caused differences in the spring hydrograph, common and partly predictable response patterns were observed that were driven by water table elevation, and the extent and duration of river water intrusion.« less

Viscoelastic Properties of Advanced Polymer Composites for Ballistic Protective Applications

DTIC Science & Technology

1994-09-01

ofthe Damaged Sample 78 Figure 69: Fracture Surface of Damage Area Near the Point of Penetration 79 Figure 70. Closer View ofthe Damaged Area...LIST OF TABLES Table 1. Basic Mechanical Properties of the Materials 6 Table 2. Initial DMA Test Results 23 Table 3. Flexural Three Point Bend... point bend testing was conducted using an Instron 1127 Universal Tester to verify the DMA test method and specimen clamping configuration. Interfacial

"How low can it go?" - Scenarios for the future of water tables and groundwater irrigated agriculture in India

NASA Astrophysics Data System (ADS)

Modi, V.; Fishman, R.

2010-12-01

Groundwater irrigation, while critical for food production and rural livelihood in many developing countries, is often unsustainable. India, the world’s largest consumer of groundwater, mostly for irrigation, is a prime example: data suggests water tables are falling in the most of its productive regions. Because of the long-term consequences for the viability and efficiency of agriculture, it is important to know how far water tables might fall and what will eventually stabilize them: will it be a reduction in water use and increases in water use efficiency (a sustainable path) or more pessimistically, an energy ‘crunch’ or the hydrological ‘bottom’. Using national-level data, we document an alarming trend of non-decreasing water withdrawals supported by increasing energy use and little, if any, improvement in efficiency. We also study in detail a particular hot spot of advanced depletion that presents a grave warning signal of how far things can go if allowed to proceed on their present course. In our study area, water tables have been falling rapidly for three decades now and reach as much as 200m, with the astounding consequence that energy use for pumping, subsidized by the state, is now worth more than the income farmers generate from its use. Despite this, the large potential for water savings in agriculture there is still unexploited. We discuss policy measures that can prevent other parts of the country from following the same disastrous trajectory.

The impact of long-term changes in water table height on carbon cycling in sub-boreal peatlands

NASA Astrophysics Data System (ADS)

Pypker, T. G.; Moore, P. A.; Waddington, J. M.; Hribljan, J. A.; Ballantyne, D.; Chimner, R. A.

2011-12-01

Peatlands are a critical component in the global carbon (C) cycle because they have been slowly sequestering atmospheric greenhouse gases as peat since the last glaciation. Today, soil C stocks in peatlands are estimated to represent 224 to 455 Pg, equal to 12-30% of the global soil C pool. At present, peatlands are estimated to sequester 76 Tg C yr-1. The flux of C to and from peatlands is likely to respond to climate change, thereby influencing atmospheric C concentrations. Peatland C budgets are tightly linked to their hydrology, hence, it is critical we understand how changes in hydrology will affect the C budgets of peatlands. The main objective of the project was to determine how long-term changes in water table height affect CO2 and CH4 fluxes from three adjacent peatlands. This study took place in the Seney National Wildlife Refuge (SNWR) in the Upper Peninsula of Michigan. SNWR is home to the largest wetland drainage project in Michigan. In 1912, ditches and dikes were created in an effort to convert approximately 20,000 ha of peatland to agriculture. The ditches and dikes were unsuccessful in creating agricultural land, but they are still in place. The manipulation of water table heights provides an opportunity to research how long-term peat drying or wetting alters C cycling in peatlands. From May to November in 2009, 2010 and 2011, we monitored CO2 fluxes using eddy covariance and chamber techniques in three adjacent peatlands with lowered, relatively unaltered ("control") and raised water table heights. In 2011, we installed CH4 analyzers to continuously monitor CH4 fluxes at the sites with high and relatively unaltered water table heights. The results are compared across sites to determine how changes in water table height might affect C fluxes sub-boreal peatlands.

Topographic Controls on Hillslope-Riparian Water Table Continuity in a set of Nested Catchments, Northern Rocky Mountains, Montana

NASA Astrophysics Data System (ADS)

Jencso, K. G.; McGlynn, B. L.; Gooseff, M. N.; Wondzell, S. M.; Bencala, K. E.; Payn, R. A.

2007-12-01

Understanding how hillslope and riparian water table dynamics influence catchment scale hydrologic response remains a challenge. In steep headwater catchments with shallow soils, topographic convergence and divergence (upslope accumulated area-UAA) is a hypothesized first-order control on the distribution of soil water and groundwater. To test the relationship between UAA and the longevity of hillslope-riparian-stream shallow groundwater connectivity, we quantified water table continuity based on 80+ recording wells distributed across 24 hillslope-riparian-stream cross-sections. Cross-section upstream catchment areas ranged in size from 0.41 to 17.2 km2, within the Tenderfoot Creek Experimental Forest (U.S. Forest Service), northern Rocky Mountains, Montana, USA. We quantified toe-slope UAA and the topographic index (TI = ln a/tanβ) with a Multiple-D- Infinity (area routing in multiple infinite downslope directions) flow accumulation algorithm analysis of 1, 3, 10, and 30m ALSM derived DEMs. Indices derived from the 10m DEM best characterized subsurface flow accumulation, highlighting the balance between the process of interest, topographic complexity, and optimal grid scale representation. Across the 24 transects, toe-slope UAA ranged from 600-40,000 m2, the TI ranged from 5-16, and riparian widths were between 0-60m. Patterns in shallow groundwater table fluctuations suggest hydrologic dynamics reflective of hillslope-riparian landscape setting. Specifically, correlations were observed between longevity of hillslope-riparian water table continuity and the size of the UAA (r2=0.84) and its topographic index (r2=.86). These observations highlight the temporal component of topographic-hydrologic relationships important for understanding threshold mediated hydrologic variables. We are working to quantify the characteristics and spatial distribution of hillslope-riparian sequences and their water table dynamics to temporally link runoff source areas to whole catchment hydrologic response.

Stochastic analysis of unsaturated steady flows above the water table

NASA Astrophysics Data System (ADS)

Severino, Gerardo; Scarfato, Maddalena; Comegna, Alessandro

2017-08-01

Steady flow takes place into a three-dimensional partially saturated porous medium where, due to their spatial variability, the saturated conductivity Ks, and the relative conductivity Kr are modeled as random space functions (RSF)s. As a consequence, the flow variables (FVs), i.e., pressure-head and specific flux, are also RSFs. The focus of the present paper consists into quantifying the uncertainty of the FVs above the water table. The simple expressions (most of which in closed form) of the second-order moments pertaining to the FVs allow one to follow the transitional behavior from the zone close to the water table (where the FVs are nonstationary), till to their far-field limit (where the FVs become stationary RSFs). In particular, it is shown how the stationary limits (and the distance from the water table at which stationarity is attained) depend upon the statistical structure of the RSFs Ks, Kr, and the infiltrating rate. The mean pressure head ><Ψ>> has been also computed, and it is expressed as <Ψ>=Ψ0>(1+ψ>), being ψ a characteristic heterogeneity function which modifies the zero-order approximation Ψ0 of the pressure head (valid for a vadose zone of uniform soil properties) to account for the spatial variability of Ks and Kr. Two asymptotic limits, i.e., close (near field) and away (far field) from the water table, are derived into a very general manner, whereas the transitional behavior of ψ between the near/far field can be determined after specifying the shape of the various input soil properties. Besides the theoretical interest, results of the present paper are useful for practical purposes, as well. Indeed, the model is tested against to real data, and in particular it is shown how it is possible for the specific case study to grasp the behavior of the FVs within an environment (i.e., the vadose zone close to the water table) which is generally very difficult to access by direct inspection.

Three-dimensional saturated-unsaturated flow with axial symmetry to a partially penetrating well in a compressible unconfined aquifer

NASA Astrophysics Data System (ADS)

Tartakovsky, Guzel D.; Neuman, Shlomo P.

2007-01-01

A new analytical solution is presented for the delayed response process characterizing flow to a partially penetrating well in an unconfined aquifer. The new solution generalizes that of Neuman (1972, 1974) by accounting for unsaturated flow above the water table. Three-dimensional, axially symmetric flow in the unsaturated zone is described by a linearized version of Richards' equation in which hydraulic conductivity and water content vary exponentially with incremental capillary pressure head relative to its air entry value (defining the interface between the saturated and unsaturated zones). Unsaturated soil properties are characterized by an exponent κ having the dimension of inverse length or, equivalently, a dimensionless exponent κD = κb, where b is initial saturated thickness. Our treatment of the unsaturated zone is similar to that of Kroszynski and Dagan (1975), who, however, have ignored internal (artesian) aquifer storage. According to Kroszynski and Dagan, aquifers that are not excessively shallow have values of κD (their parameter a) much greater than 10. We find that in such typical cases, unsaturated flow has little impact on early and late dimensionless time drawdown a short distance below the water table. Unsaturated flow causes drawdown to increase slightly at intermediate dimensionless time values that represent transition from an early artesian-dominated to a late water-table-dominated flow regime. Delayed drainage from the unsaturated zone becomes less and less important as κD increases; as κD → ∞, this effect dies out, and drawdown is controlled entirely by delayed decline in the water table as in the model of Neuman. The unsaturated zone has a major impact on drawdown at intermediate time and a significant impact at early and late times, in the atypical case of κD ≤ 1, becoming the dominant factor as κD approaches zero (the soil water retention capacity becomes very large and/or saturated thickness becomes insignificant). Our new solution was used to analyze field data from a pumping test conducted by Moench et al. (2001) in a glacial outwash deposit at Cape Cod, Massachusetts. The solution was fitted individually and simultaneously to time-drawdown data from 20 piezometers and observation wells and simultaneously to data from three piezometers in each of two clusters at various depths and distances from the pumping well, with very good results. Our parameter estimates of hydraulic conductivities from the simultaneous fit are similar to those obtained previously by Moench (2004), but our estimates of specific yield and storage are smaller and larger, respectively, while our estimate of κ is not comparable with his estimates of three empirical parameters.

Land Retirement as a Habitat Restoration Tool

NASA Astrophysics Data System (ADS)

Singh, P. N.; Wallender, W. W.

2007-12-01

Use of intensive irrigation in arid and semi-arid areas usually leads to gradual salination of the soil leading to crop yield decline. The salination problem is mitigated by applying irrigation in excess of crop requirements, which leaches the excess salt load to the groundwater. Insufficient natural or man made drainage to dispose off this saline recharge to the groundwater leads to a gradual rise in the water table and eventual encroachment upon the root zone. This may ultimately make the land unfit for any economically productive activity. The abandoned land may even lead to desertification with adverse environmental consequences. In drainage basins with no surface outflow (sometimes called closed basins), land retirement has been proposed as a management tool to address this problem. Land retirement essentially entails intentionally discontinuing irrigation of selected farmlands with the expectation that the shallow water table beneath those lands should drop and the root zone salinity level should decrease. In the San Joaquin Valley of California, intensive irrigation in conjunction with a shallow underlying layer of clay, known as the Corcoran clay layer and absence of a drainage system caused the root zone to become highly saline and the shallow water table to rise. Land retirement would remove from production those farmlands contributing the poorest quality subsurface drain water. Based on numerical models results, it was expected that with land retirement of substantial irrigated lands with poor drainage characteristics, beneath which lies shallow groundwater with high salt load, the shallow water table beneath those lands should drop. A part of the retired lands could also be used for wildlife habitat. A potential negative side of the land retirement option that has to be considered is that in certain enabling evapotranspiration, soil and water table conditions, water will be drawn upwards and evaporated, leaving a deposit of salts on the surface and in the root zone. Salt on the surface may then be wind blown to adjacent areas creating a potential environmental hazard. Using field results from the U.S. Department of the Interior Land Retirement Demonstration Project at the Tranquillity site located in western Fresno County, principles of mass balance in a fixed control volume, the HYDRUS-1D Software Package for Simulating the One-Dimensional Movement of Water, Heat, and Multiple Solutes in Variably-Saturated Media, and PEST, a model-independent parameter optimizer, we have investigated the processes of soil water and salinity movement in the root zone and the deep vadose zone. Various combinations of evapotranspiration, soil water retention properties, water table condition and top and bottom boundary condition were tested. We show that certain Land Retirement scenarios decrease shallow water table and soil water salinity and enhance development of native plants as a means to facilitate habitat restoration for certain combination of soil and bottom boundary condition. Other combinations are not sustainable.

Flow to a well in a water-table aquifer: An improved laplace transform solution

USGS Publications Warehouse

Moench, A.F.

1996-01-01

An alternative Laplace transform solution for the problem, originally solved by Neuman, of constant discharge from a partially penetrating well in a water-table aquifer was obtained. The solution differs from existing solutions in that it is simpler in form and can be numerically inverted without the need for time-consuming numerical integration. The derivation invloves the use of the Laplace transform and a finite Fourier cosine series and avoids the Hankel transform used in prior derivations. The solution allows for water in the overlying unsaturated zone to be released either instantaneously in response to a declining water table as assumed by Neuman, or gradually as approximated by Boulton's convolution integral. Numerical evaluation yields results identical with results obtained by previously published methods with the advantage, under most well-aquifer configurations, of much reduced computation time.

The Stream Table in Physical Geography Instruction.

ERIC Educational Resources Information Center

Wikle, Thomas A.; Lightfoot, Dale R.

1997-01-01

Outlines a number of activities to be conducted with a stream table (large wooden box filled with sediment and designed for water to pass through) in class. Activities illustrate such fluvial processes as stream meandering, erosion, transportation, and deposition. Includes a diagram for constructing a stream table. (MJP)

Layered ejecta craters and the early water/ice aquifer on Mars

NASA Astrophysics Data System (ADS)

Oberbeck, V. R.

2009-03-01

A model for emplacement of deposits of impact craters is presented that explains the size range of Martian layered ejecta craters between 5 km and 60 km in diameter in the low and middle latitudes. The impact model provides estimates of the water content of crater deposits relative to volatile content in the aquifer of Mars. These estimates together with the amount of water required to initiate fluid flow in terrestrial debris flows provide an estimate of 21% by volume (7.6 × 107 km3) of water/ice that was stored between 0.27 and 2.5 km depth in the crust of Mars during Hesperian and Amazonian time. This would have been sufficient to supply the water for an ocean in the northern lowlands of Mars. The existence of fluidized craters smaller than 5 km diameter in some places on Mars suggests that volatiles were present locally at depths less than 0.27 km. Deposits of Martian craters may be ideal sites for searches for fossils of early organisms that may have existed in the water table if life originated on Mars.

Water movement through thick unsaturated zones overlying the central High Plains aquifer, southwestern Kansas, 2000-2001

USGS Publications Warehouse

McMahon, Peter B.; Dennehy, K.F.; Michel, R.L.; Sophocleous, M.A.; Ellett, K.M.; Hurlbut, D.B.

2003-01-01

The role of irrigation as a driving force for water and chemical movement to the central High Plains aquifer is uncertain because of the thick unsaturated zone overlying the aquifer. Water potentials and profiles of tritium, chloride, nitrate, and pesticide concentrations were used to evaluate water movement through thick unsaturated zones overlying the central High Plains aquifer at three sites in southwestern Kansas. One site was located in rangeland and two sites were located in areas dominated by irrigated agriculture. In 2000?2001, the depth to water at the rangeland site was 50 meters and the depth to water at the irrigated sites was about 45.4 meters. Irrigation at the study sites began in 1955?56. Measurements of matric potential and volumetric water content indicate wetter conditions existed in the deep unsaturated zone at the irrigated sites than at the rangeland site. Total water potentials in the unsaturated zone at the irrigated sites systematically decreased with depth to the water table, indicating a potential existed for downward water movement from the unsaturated zone to the water table at those sites. At the rangeland site, total water potentials in the deep unsaturated zone indicate small or no potential existed for downward water movement to the water table. Postbomb tritium was not detected below a depth of 1.9 meters in the unsaturated zone or in ground water at the rangeland site. In contrast, postbomb tritium was detected throughout most of the unsaturated zone and in ground water at both irrigated sites. These results indicate post-1953 water moved deeper in the unsaturated zone at the irrigated sites than at the rangeland site. The depth of the interface between prebomb and postbomb tritium and a tritium mass-balance method were used to estimate water fluxes in the unsaturated zone at each site. The average water fluxes at the rangeland site were 5.4 and 4.4 millimeters per year for the two methods, which are similar to the average water flux (5.1 millimeters per year) estimated using a chloride mass-balance method. Tritium profiles in the unsaturated zone at the irrigated sites were complicated by the presence of tritium-depleted intervals separating upper and lower zones containing postbomb tritium. If the interface between prebomb and postbomb tritium was at the top of the tritium-depleted interval and postbomb tritium detected beneath that interval was from the declining water table in the area, then the average water flux at the irrigated sites was estimated to be 21 to 54 millimeters per year. If postbomb tritium detected beneath the tritium-depleted interval was from bypass or preferential water movement through the local unsaturated zone instead of the declining water table, then the minimum water flux at the irrigated sites was estimated to be 106 to 116 millimeters per year. In either case, water fluxes at the irrigated sites were at least 4 to 12 times larger than the flux at the rangeland site, indicating irrigation was an important driving force for water movement through the unsaturated zone. The presence of postbomb tritium and large nitrate and total pesticide concentrations (24 milligrams per liter as nitrogen and 0.923 microgram per liter, respectively) in ground water at the irrigated sites indicates irrigation water also was an important driving force for chemical movement to the water table. The persistence of a downward hydraulic gradient from the deep unsaturated zone to the water table at the irrigated sites, in addition to large nitrate and atrazine concentrations in deep soil water (34 milligrams per liter as nitrogen and 0.79 microgram per liter, respectively), indicate that the deep unsaturated zone will be a source of nitrate and atrazine to the aquifer in the future.

Computer Program for Calculating Hydrodynamic Properties of Shock Waves in Sea Water.

DTIC Science & Technology

1982-02-01

White Oak Labs. 13. NUMG*CNOF WAGES tS. ed~eiYONwG AGECY NAM S AOOeSSl1 diffrent froem CooIn.1" Offieo) 1. SECURITY ’ CLASS. (of this ropoft) Unclassif...calculaNTwithout use of tables opies of the four magnetic 00 ~’ 1473 oo’-lo. or I NO 4S 51 OGSOLETZ SECURITY CLAISIPPICAAK -HIS CP5 AoG ’When Dove 60fed...initial pressure po-0. Neither of the two plane. In Fig. 1, the possible states of a given equations-of-state are complete in the sense that fluid just

Reference manual for data base on Nevada well logs

USGS Publications Warehouse

Bauer, E.M.; Cartier, K.D.

1995-01-01

The U.S. Geological Survey and Nevada Division of Water Resources are cooperatively using a data base for are cooperatively using a data base for managing well-log information for the State of Nevada. The Well-Log Data Base is part of an integrated system of computer data bases using the Ingres Relational Data-Base Management System, which allows efficient storage and access to water information from the State Engineer's office. The data base contains a main table, two ancillary tables, and nine lookup tables, as well as a menu-driven system for entering, updating, and reporting on the data. This reference guide outlines the general functions of the system and provides a brief description of data tables and data-entry screens.

Transient desorption of water vapor - A potential source of error in upper atmosphere rocket experiments

NASA Technical Reports Server (NTRS)

Kendall, B. R. F.; Weeks, J. O.

1974-01-01

Results of measurements of the outgassing rates of samples of materials and surface finishes used on the outer skins of rocket-borne experiment packages in simulated rocket ascents. The results showed outgassing rates for anodized aluminum in the second minute of flight which are two to three orders of magnitude higher than those given in typical tables of outgassing rates. The measured rates for aluminum with chromate conversion surface coatings were also abnormally high. These abnormally high initial rates fell quickly after about five to ten minutes to values comparable with those in the published literature. It is concluded that anodized and chromate conversion coatings on the aluminum outer surfaces of a sounding rocket experiment package will cause gross distortion of the true water vapor environment.

Selected hydrologic data from a wastewater spray disposal site on Hilton Head Island, South Carolina

USGS Publications Warehouse

Speiran, G.K.; Belval, D.L.

1985-01-01

This study presents data collected during a study of the effects on the water table aquifer from wastewater application at rates of up to 5 inches per week on a wastewater spray disposal site on Hilton Head Island, South Carolina. The study was conducted from April 1982 through December 1983. The disposal site covers approximately 14 acres. Water level and water quality data from organic, inorganic, and nutrient analyses from the water table aquifer to a depth of 30 ft and similar water quality data from the wastewater treatment plant are included. (USGS)

Groundwater Recharge Assessment in a Remote Region of Colombia Through Citizen Science

NASA Astrophysics Data System (ADS)

Gomez, A. M.; Wise, E.; Riveros-Iregui, D.

2017-12-01

Understanding water dynamic and storage is essential for decision making in hydrology issues. In remote groundwater-dependent regions affected by population displacement and land over exploitation, especially in developing economies, limited data hinders the production of information necessary to formulate and implement effective water management plans. The community science research approach, which seeks to solve scientific questions with the participation of the community at various levels, represents an opportunity in these regions. We present results of a citizen science project developed to improve the conceptualization of groundwater flow path and to estimate the monthly direct recharge to the shallow aquifer in a remote rural region, the Man River watershed, located in one of the last foothills between the Western and Central Andes cordillera in Colombia. This project was conducted by: i) implementing a water level monitoring network aided by the community to collect weekly data from 2007 to 2010; ii) comparing the precipitation data and water table time series to identify the response of the shallow aquifer to the wet season; iii) conceptualizing specific groundwater-surface interactions through water table spatial analysis; and iv) estimating direct groundwater recharge using the Water Table Fluctuation method. Water quality test results were shared with the local community. Results show that groundwater interacts with the main tributaries to the Man River. Two scenarios were identified related to water table temporal behavior: (1) the water table rises during the transition from the dry to the wet season (between March and April), and (2) it increases one month after this transition. In general, groundwater levels descend in November, which is the end of the wet season. The work with the community provided useful insights for interpreting the collected data and allowed for information exchange concerning the groundwater quality and methods for improving the sanitary conditions of the dug wells. This project represents a valuable strategy for adding information to the hydrogeological conceptual model at low cost. It also provides opportunities for the implementation of a more informed water management plan while improving water quality and accessibility at the domestic household level.

[The marketing evaluation of the consumers' preference as regards the use of medicinal and medicinal table mineral waters].

PubMed

Babaskin, D V; Babaskina, L I; Pavlova, A V

2017-12-28

The development of modern technologies in physiotherapy with the use of mineral waters, the expansion of the assortment of the medicinal and medicinal table waters as well as increasing the competitive advantages of domestic products require the more extensive marketing survey of the consumers' preferences in the market of mineral waters. The objective of the present study was the marketing evaluation of the consumers' preference in the segment of medicinal and medicinal table mineral waters in the city of Moscow. The survey involved 697 consumers of medicinal and medicinal table mineral waters. The sampling was carried out by the deterministic quota method. The field research was conducted by means of personal verbal interviews (32%) and the CATI to Web method (phone recruiting and on-line questioning) (68%) with the use of the structured questionnaire. Positioning was carried out making use of the two-dimensional schematic map and scoring assessment on an individual basis with calculation of integrated indicators. The marketing evaluation has demonstrated that the principal motive for purchasing mineral waters in more than 40% of respondents was the treatment and prevention of various diseases including disturbances in the urogenital system as well as digestive and respiratory disorders that appear to be the most frequent reasons for the consumption of mineral waters. The main factors that form the preferences of the consumers as regards the use of a concrete variety of mineral waters were elucidated. Of crucial importance for approximately 40% of the consumers (p<0.01) proved to be their health condition, the medical indications, and the available information about the therapeutic effectiveness of one or another type of mineral waters. Other factors were the quality of mineral water, its cost, the manufacturer and/or place of production, the attractiveness of the packaging, etc. The evaluation of the positioning of the mineral water consumers' preferences made it possible to identify the most preferable products in the group of medicinal mineral waters and in the group of medicinal table mineral waters. The mechanisms governing the formation of the consumers' preferences as regards the use of various mineral waters have been clarified in the course of the present study.

Ground-water resources of the Middle Loup division of the lower Platte River basin, Nebraska, with a section on Chemical quality of the ground water

USGS Publications Warehouse

Brown, Delbert Wayne; Rainwater, Frank Hays

1955-01-01

The Middle Loup division of the lower Platte River basin is an area of 650 square miles which includes the Middle Loup River valley from the confluence of the Middle and North Loup Rivers in Howard County, Nebr., to the site of the diversion dam that the U. S. Bureau of Reclamation proposes to construct in Blaine County near Milburn, Nebr. It also includes land in Howard and Sherman Counties designated by the Bureau of Reclamation as the Farwell unit. Irrigable land in this division is present on both sides of the Middle Loup River and along its tributaries. Most of the Middle Loup River valley is already irrigated by the Middle Loup Public Power and Irrigation District, which is strictly an irrigation enterprise. The uplands are not irrigated. Loess, dune sand, gravel, silt, and clay of Pleistocene or Recent age are exposed in the report area. These unconsolidated sediments rest on bedrock consisting of alternating layers of shale, mudstone, sandstone, and limestone, which are essentially fiat lying or slightly warped. The Ogallala formation, of Tertiary (Pliocene) age, immediately underlies the Pleistocene sediments and rests on the Pierre shale of Cretaceous age. Belts of alluvium occupy the Middle Loup River valley and the valleys of the principal streams in the area. The soils, dune sand, and terrace deposits are the most recent deposits. The Ogallala formation is water bearing and is the source of supply for some domestic and livestock wells. The saturated part of the sand and gravel formations of Pleistocene age, which yields water freely to wells, is the most important aquifer in the Middle Loup division. The water generally is under water-table conditions. The yields of properly constructed wells range from a few gallons per minute (gpm) to as much as 1,800 gpm. Some wells tap water in both the sand and gravel of Pleistocene age and in the underlying Ogallala formation. No wells are known to penetrate into formations older than the Ogallala. Fluctuations of the water table indicate changes in the amount of ground water stored in the water-bearing formations. The principal factors controlling the rise of the water table are the amount of precipitation within the area, the quantity of water coming into the area as underflow from the west and northwest, seepage from the Middle Loup River at times when the water surface in the river is higher than the adjoining water table, and the infiltration of irrigation water not utilized by vegetation or lost by runoff or evaporation. The principal factors controlling the decline of the water table are the discharge as effluent seepage into the Middle Loup River and its tributaries, the amount of water pumped from wells, evapotranspiration losses, and the amount of water leaving the area as underflow. Periodic water-level measurements were made in a total of 241 observation wells during the period 1948-50. Hydrographs of three observation wells having a longer period of record (1934-50) indicate that the water table rose slightly from 1934 until 1950 and that it remained nearly constant during the 1950 water year. The configuration of the water table in the Middle Loup division shows that, except north and northwest of Sargent, the Middle Loup River is an effluent, or gaining, stream throughout its entire length in this area. Thus any rise or fall in the ground-water level will increase or decrease the discharge of the river. The river recharges the ground- water reservoir only during periods when it is at flood stage. The depth to the water table from the land surface is governed largely by irregularities in topography. The depth to water is less than 10 feet near the river and increases to as much as 60 feet near the valley margins and the bordering intermediate slopes. In the Far- well unit the depth to water is more than 100 feet and in some parts more than 150 feet. Ground water pumped from wells is the source of supply for the principal municipalities in th

40 CFR 132.3 - Adoption of criteria.

Code of Federal Regulations, 2012 CFR

2012-07-01

... with: (a) The acute water quality criteria for protection of aquatic life in Table 1 of this part, or a... chronic water quality criteria for protection of aquatic life in Table 2 of this part, or a site-specific... QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM § 132.3 Adoption of criteria. The Great Lakes States and...

40 CFR 132.3 - Adoption of criteria.

Code of Federal Regulations, 2013 CFR

2013-07-01

... with: (a) The acute water quality criteria for protection of aquatic life in Table 1 of this part, or a... chronic water quality criteria for protection of aquatic life in Table 2 of this part, or a site-specific... QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM § 132.3 Adoption of criteria. The Great Lakes States and...

40 CFR 132.3 - Adoption of criteria.

Code of Federal Regulations, 2010 CFR

2010-07-01

... with: (a) The acute water quality criteria for protection of aquatic life in Table 1 of this part, or a... chronic water quality criteria for protection of aquatic life in Table 2 of this part, or a site-specific... QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM § 132.3 Adoption of criteria. The Great Lakes States and...

40 CFR 132.3 - Adoption of criteria.

Code of Federal Regulations, 2011 CFR

2011-07-01

... with: (a) The acute water quality criteria for protection of aquatic life in Table 1 of this part, or a... chronic water quality criteria for protection of aquatic life in Table 2 of this part, or a site-specific... QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM § 132.3 Adoption of criteria. The Great Lakes States and...

Chemical Characterization of Simulated Boiling Water Reactor Coolant

DTIC Science & Technology

1990-05-01

33 Table 3. 1: BCCL Sample Block Design Calculations ........................................... 45 Table 5.1: Gas Absorption...cover gas . The cool, degassed pure water is pumped through a regenerative heat exchanger and then through an electric feedwater heater. The feedwater is...POINTS DWCMRHEAT DOWNOMER---EXCHANGER CHEMICAL GAHP INJECTIOIN PUMP SYSTEM COIVER GAS IN-CLIRE SECTION CAGN TANK RECOMBINER! ______ DEMINERALIZER (Cic

Microtropography and water table fluctuation in a sphagnum mire

Treesearch

E.S. Verry

1984-01-01

A detailed organic soil profile description, 22 years of continuous water table records, and a hummock-hollow level survey were examined at a small Minnesota mire (a bog with remnants of poor fen vegetation). Variation in the level survey suggests that hollows be used to minimize variation when detailed topographic information is needed and to match profile...

Investigations on Local Seismic Phases and Modeling of Seismic Signals

DTIC Science & Technology

1993-10-31

basement is 1 km. The water table, wt , is from Doty and Thordarson (1983). It separates the dry, DT, and the wet, WT, tuff levels. Above these volcanic...regional variations of t*(f) in the United States. Geophys. J. R. astr. Soc. 82 , 125-140 Doty, G. C. and W. Thordarson , 1983. Water table in rocks of

Obliquity (41kyr) Paced SE Asian Monsoon Variability Following the Miocene Climate Transition

NASA Astrophysics Data System (ADS)

Heitmann, E. O.; Breecker, D.; Ji, S.; Nie, J.

2016-12-01

We investigated Asian monsoon variability during the Miocene, which may provide a good analog for the future given the lack of northern hemisphere ice sheets. In the Miocene Yanwan Section (Tianshui Basin, China) 25cm thick CaCO3-cemented horizons overprint siltstones every 1m. We suggest this rhythmic layering records variations in water availability influenced by the Asian monsoon. We interpret the siltstones as stacked soils that formed in a seasonal climate with a fluctuating water table, evidenced by roots, clay films, mottling, presence of CaCO3 nodules, and stacked carbonate nodule δ13C and δ18O profiles that mimic modern soils. We interpret the CaCO3-cemented horizons as capillary-fringe carbonates that formed in an arid climate with a steady water table and high potential evapotranspiration (PET), evidenced by sharp upper and basal contacts, micrite, sparite, and root-pore cements. The magnetostratigraphy-based age model indicates obliquity-pacing of the CaCO3-cemented horizons suggesting an orbital control on water availability, for which we propose two mechanisms: 1) summer monsoon strength, moderated by the control of obliquity on the cross-equatorial pressure gradient, and 2) PET, moderated by the control of precession on 35oN summer insolation. We use orbital configurations to predict lithology. Coincidence of obliquity minima and insolation maxima drives strong summer monsoons, seasonal variations in water table depth and soil formation. Coincidence of obliquity maxima and insolation minima drives weak summer monsoons, high PET, and carbonate accumulation above a deepened, stable water table. Coincidence of obliquity and insolation minima drives strong monsoons, low PET, and a high water table, explaining the evidence for aquatic plants previously observed in this section. Southern hemisphere control of summer monsoon variability in the Miocene may thus have resulted in large water availability variations in central China.

Investigating the role of gas bubble formation and entrapment in contaminated aquifers: Reactive transport modelling

USGS Publications Warehouse

Amos, Richard T.; Mayer, K. Ulrich

2006-01-01

In many natural and contaminated aquifers, geochemical processes result in the production or consumption of dissolved gases. In cases where methanogenesis or denitrification occurs, the production of gases may result in the formation and growth of gas bubbles below the water table. Near the water table, entrapment of atmospheric gases during water table rise may provide a significant source of O2 to waters otherwise depleted in O2. Furthermore, the presence of bubbles will affect the hydraulic conductivity of an aquifer, resulting in changes to the groundwater flow regime. The interactions between physical transport, biogeochemical processes, and gas bubble formation, entrapment and release is complex and requires suitable analysis tools. The objective of the present work is the development of a numerical model capable of quantitatively assessing these processes. The multicomponent reactive transport code MIN3P has been enhanced to simulate bubble growth and contraction due to in-situ gas production or consumption, bubble entrapment due to water table rise and subsequent re-equilibration of the bubble with ambient groundwater, and permeability changes due to trapped gas phase saturation. The resulting formulation allows for the investigation of complex geochemical systems where microbially mediated redox reactions both produce and consume gases as well as affect solution chemistry, alkalinity, and pH. The enhanced model has been used to simulate processes in a petroleum hydrocarbon contaminated aquifer where methanogenesis is an important redox process. The simulations are constrained by data from a crude oil spill site near Bemidji, MN. Our results suggest that permeability reduction in the methanogenic zone due to in-situ formation of gas bubbles, and dissolution of entrapped atmospheric bubbles near the water table, both work to attenuate the dissolved gas plume emanating from the source zone. Furthermore, the simulations demonstrate that under the given conditions more than 50% of all produced CH4 partitions to the gas phase or is aerobically oxidised near the water table, suggesting that these processes should be accounted for when assessing the rate and extent of methanogenic degradation of hydrocarbons.

Accounting for intracell flow in models with emphasis on water table recharge and stream-aquifer interaction: 1. Problems and concepts

USGS Publications Warehouse

Jorgensen, Donald G.; Signor, Donald C.; Imes, Jeffrey L.

1989-01-01

Intracell flow is important in modeling cells that contain both sources and sinks. Special attention is needed if recharge through the water table is a source. One method of modeling multiple sources and sinks is to determine the net recharge per cell. For example, for a model cell containing both a sink and recharge through the water table, the amount of recharge should be reduced by the ratio of the area of influence of the sink within the cell to the area of the cell. The reduction is the intercepted portion of the recharge. In a multilayer model this amount is further reduced by a proportion factor, which is a function of the depth of the flow lines from the water table boundary to the internal sink. A gaining section of a stream is a typical sink. The aquifer contribution to a gaining stream can be conceptualized as having two parts; the first part is the intercepted lateral flow from the water table and the second is the flow across the streambed due to differences in head between the water level in the stream and the aquifer below. The amount intercepted is a function of the geometry of the cell, but the amount due to difference in head across the stream bed is largely independent of cell geometry. A discharging well can intercept recharge through the water table within a model cell. The net recharge to the cell would be reduced in proportion to the area of influence of the well within the cell. The area of influence generally changes with time. Thus the amount of intercepted recharge and net recharge may not be constant with time. During periods when the well is not discharging there will be no intercepted recharge even though the area of influence from previous pumping may still exist. The reduction of net recharge per cell due to internal interception of flow will result in a model-calculated mass balance less than the prototype. Additionally the “effective transmissivity” along the intercell flow paths may be altered when flow paths are occupied by intercepted recharge.

Responses of riparian cottonwoods to alluvial water table declines

USGS Publications Warehouse

Scott, M.L.; Shafroth, P.B.; Auble, G.T.

1999-01-01

Human demands for surface and shallow alluvial groundwater have contributed to the loss, fragmentation, and simplification of riparian ecosystems. Populus species typically dominate riparian ecosystems throughout arid and semiarid regions of North American and efforts to minimize loss of riparian Populus requires an integrated understanding of the role of surface and groundwater dynamics in the establishment of new, and maintenance of existing, stands. In a controlled, whole-stand field experiment, we quantified responses of Populus morphology, growth, and mortality to water stress resulting from sustained water table decline following in-channel sand mining along an ephemeral sandbed stream in eastern Colorado, USA. We measured live crown volume, radial stem growth, annual branch increment, and mortality of 689 live Populus deltoides subsp. monilifera stems over four years in conjunction with localized water table declines. Measurements began one year prior to mining and included trees in both affected and unaffected areas. Populus demonstrated a threshold response to water table declines in medium alluvial sands; sustained declines ???1 m produced leaf desiccation and branch dieback within three weeks and significant declines in live crown volume, stem growth, and 88% mortality over a three-year period. Declines in live Crown volume proved to be a significant leading indicator of mortality in the following year. A logistic regression of tree survival probability against the prior year's live crown volume was significant (-2 log likelihood = 270, ??2 with 1 df = 232, P < 0.0001) and trees with absolute declines in live crown volume of ???30 during one year had survival probabilities <0.5 in the following year. In contrast, more gradual water table declines of ~0.5 m had no measurable effect on mortality, stem growth, or live crown volume and produced significant declines only in annual branch growth increments. Developing quantitative information on the timing and extent of morphological responses and mortality of Populus to the rate, depth, and duration of water table declines can assist in the design of management prescriptions to minimize impacts of alluvial groundwater depletion on existing riparian Populus forests.

Investigating the role of gas bubble formation and entrapment in contaminated aquifers: Reactive transport modelling

NASA Astrophysics Data System (ADS)

Amos, Richard T.; Ulrich Mayer, K.

2006-09-01

In many natural and contaminated aquifers, geochemical processes result in the production or consumption of dissolved gases. In cases where methanogenesis or denitrification occurs, the production of gases may result in the formation and growth of gas bubbles below the water table. Near the water table, entrapment of atmospheric gases during water table rise may provide a significant source of O 2 to waters otherwise depleted in O 2. Furthermore, the presence of bubbles will affect the hydraulic conductivity of an aquifer, resulting in changes to the groundwater flow regime. The interactions between physical transport, biogeochemical processes, and gas bubble formation, entrapment and release is complex and requires suitable analysis tools. The objective of the present work is the development of a numerical model capable of quantitatively assessing these processes. The multicomponent reactive transport code MIN3P has been enhanced to simulate bubble growth and contraction due to in-situ gas production or consumption, bubble entrapment due to water table rise and subsequent re-equilibration of the bubble with ambient groundwater, and permeability changes due to trapped gas phase saturation. The resulting formulation allows for the investigation of complex geochemical systems where microbially mediated redox reactions both produce and consume gases as well as affect solution chemistry, alkalinity, and pH. The enhanced model has been used to simulate processes in a petroleum hydrocarbon contaminated aquifer where methanogenesis is an important redox process. The simulations are constrained by data from a crude oil spill site near Bemidji, MN. Our results suggest that permeability reduction in the methanogenic zone due to in-situ formation of gas bubbles, and dissolution of entrapped atmospheric bubbles near the water table, both work to attenuate the dissolved gas plume emanating from the source zone. Furthermore, the simulations demonstrate that under the given conditions more than 50% of all produced CH 4 partitions to the gas phase or is aerobically oxidised near the water table, suggesting that these processes should be accounted for when assessing the rate and extent of methanogenic degradation of hydrocarbons.

Modelling of seasonal dynamics of Wetland-Groundwater flow interaction in the Canadian Prairies

NASA Astrophysics Data System (ADS)

Ali, Melkamu; Nussbaumer, Raphaël; Ireson, Andrew; Keim, Dawn

2015-04-01

Wetland-shallow groundwater interaction is studied at the St. Denis National Wildlife Area in Saskatchewan, Canada, located within the northern glaciated prairies of North America. Ponds in the Canadian Prairies are intermittently connected by fill-spill processes in the spring and growing season of some wetter years. The contribution of the ponds and wetlands to groundwater is still a significant research challenge. The objective of this study is to evaluate model's ability to reproduce observed effects of groundwater-wetland interactions including seasonal pattern of shallow groundwater table, intended flow direction and to quantify the depression induced infiltration from the wetland to the surrounding uplands. The integrated surface-wetland-shallow groundwater processes and the changes in land-energy and water balances caused by the flow interaction are simulated using ParFlow-CLM at a small watershed of 1km2 containing both permanent and seasonal wetland complexes. We compare simulated water table depth with piezometers reading monitored by level loggers at the watershed. We also present the strengths and limitations of the model in reproducing observed behaviour of the groundwater table response to the spring snowmelt and summer rainfall. Simulations indicate that the shallow water table at the uphill recovers quickly after major rainfall events in early summer that generates lateral flow to the pond. In late summer, the wetland supplies water to the surrounding upland when the evapotranspiration is higher than the precipitation in which more water from the root zone is up taken by plants. Results also show that Parflow-CLM is able to reasonably simulate the water table patterns response to summer rainfall, while it is insufficient to reproduce the spring snowmelt infiltration which is the most dominant hydrological process in the Prairies.

High temporal resolution modeling of the impact of rain, tides, and sea level rise on water table flooding in the Arch Creek basin, Miami-Dade County Florida USA.

PubMed

Sukop, Michael C; Rogers, Martina; Guannel, Greg; Infanti, Johnna M; Hagemann, Katherine

2018-03-01

Modeling of groundwater levels in a portion of the low-lying coastal Arch Creek basin in northern Miami-Dade County in Southeast Florida USA, which is subject to repetitive flooding, reveals that rain-induced short-term water table rises can be viewed as a primary driver of flooding events under current conditions. Areas below 0.9m North American Vertical Datum (NAVD) elevation are particularly vulnerable and areas below 1.5m NAVD are vulnerable to exceptionally large rainfall events. Long-term water table rise is evident in the groundwater data, and the rate appears to be consistent with local rates of sea level rise. Linear extrapolation of long-term observed groundwater levels to 2060 suggest roughly a doubling of the number of days when groundwater levels exceed 0.9m NAVD and a threefold increase in the number of days when levels exceed 1.5m NAVD. Projected sea level rise of 0.61m by 2060 together with increased rainfall lead to a model prediction of frequent groundwater-related flooding in areas<0.9m NAVD. However, current simulations do not consider the range of rainfall events that have led to water table elevations>1.5m NAVD and widespread flooding of the area in the past. Tidal fluctuations in the water table are predicted to be more pronounced within 600m of a tidally influenced water control structure that is hydrodynamically connected to Biscayne Bay. The inland influence of tidal fluctuations appears to increase with increased sea level, but the principal driver of high groundwater levels under the 2060 scenario conditions remains groundwater recharge due to rainfall events. Copyright © 2017 Elsevier B.V. All rights reserved.

Landscape heterogeneity, soil climate, and carbon exchange in a boreal black spruce forest.

PubMed

Dunn, Allison L; Wofsy, Steven C; v H Bright, Alfram

2009-03-01

We measured soil climate and the turbulent fluxes of CO2, H2O, heat, and momentum on short towers (2 m) in a 160-yr-old boreal black spruce forest in Manitoba, Canada. Two distinct land cover types were studied: a Sphagnum-dominated wetland, and a feathermoss (Pleurozium and Hylocomium)-dominated upland, both lying within the footprint of a 30-m tower, which has measured whole-forest carbon exchange since 1994. Peak summertime uptake of CO2, was higher in the wetland than for the forest as a whole due to the influence of deciduous shrubs. Soil respiration rates in the wetland were approximately three times larger than in upland soils, and 30% greater than the mean of the whole forest, reflecting decomposition of soil organic matter. Soil respiration rates in the wetland were regulated by soil temperature, which was in turn influenced by water table depth through effects on soil heat capacity and conductivity. Warmer soil temperatures and deeper water tables favored increased heterotrophic respiration. Wetland drainage was limited by frost during the first half of the growing season, leading to high, perched water tables, cool soil temperatures, and much lower respiration rates than observed later in the growing season. Whole-forest evapotranspiration increased as water tables dropped, suggesting that photosynthesis in this forest was rarely subject to water stress. Our data indicate positive feedback between soil temperature, seasonal thawing, heterotrophic respiration, and evapotranspiration. As a result, climate warming could cause covariant changes in soil temperature and water table depths that may stimulate photosynthesis and strongly promote efflux of CO2 from peat soils in boreal wetlands.

33 CFR Table 4 to Subpart H of... - Weights (Pounds) of Outboard Motor and Related Equipment for Various Boat Horsepower Ratings

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Weights (Pounds) of Outboard Motor and Related Equipment for Various Boat Horsepower Ratings 4 Table 4 to Subpart H of Part 183... or Less Pt. 183, Subpt. H, Table 4 Table 4 to Subpart H of Part 183—Weights (Pounds) of Outboard...

Simplifiying global biogeochemistry models to evaluate methane emissions

NASA Astrophysics Data System (ADS)

Gerber, S.; Alonso-Contes, C.

2017-12-01

Process-based models are important tools to quantify wetland methane emissions, particularly also under climate change scenarios, evaluating these models is often cumbersome as they are embedded in larger land-surface models where fluctuating water table and the carbon cycle (including new readily decomposable plant material) are predicted variables. Here, we build on these large scale models but instead of modeling water table and plant productivity we provide values as boundary conditions. In contrast, aerobic and anaerobic decomposition, as well as soil column transport of oxygen and methane are predicted by the model. Because of these simplifications, the model has the potential to be more readily adaptable to the analysis of field-scale data. Here we determine the sensitivity of the model to specific setups, parameter choices, and to boundary conditions in order to determine set-up needs and inform what critical auxiliary variables need to be measured in order to better predict field-scale methane emissions from wetland soils. To that end we performed a global sensitivity analysis that also considers non-linear interactions between processes. The global sensitivity analysis revealed, not surprisingly, that water table dynamics (both mean level and amplitude of fluctuations), and the rate of the carbon cycle (i.e. net primary productivity) are critical determinants of methane emissions. The depth-scale where most of the potential decomposition occurs also affects methane emissions. Different transport mechanisms are compensating each other to some degree: If plant conduits are constrained, methane emissions by diffusive flux and ebullition compensate to some degree, however annual emissions are higher when plants help to bypass methanotrophs in temporally unsaturated upper layers. Finally, while oxygen consumption by plant roots help creating anoxic conditions it has little effect on overall methane emission. Our initial sensitivity analysis helps guiding further model development and improvement. However, an important goal for our model is to use it in field settings as a tool to deconvolve the different processes that contribute to the net transfer of methane from soils to atmosphere.

Ground Water Atlas of the United States: Segment 12, Connecticut, Maine, Massachusetts, New Hampshire, New York, Rhode Island, Vermont

USGS Publications Warehouse

Olcott, Perry G.

1995-01-01

The State of New York and the six New England States of Maine, Vermont, New Hampshire, Massachusetts, Connecticut, and Rhode Island compose Segment 12 of this Atlas (fig. 1). The seven States have a total land area of about 116,000 square miles (table 1); all but a small area in southwestern New York has been glaciated. Population in the States of Segment 12 totals about 30,408,000 (table 1) and is concentrated in southern and eastern Massachusetts, Connecticut, Rhode Island, and especially New York (fig. 1). The northern part of the segment and the mountainous areas of New York and much of New Hampshire, Vermont, and Maine are sparsely populated. The percentage of population supplied from ground-water sources during 1980 was 54 to 60 percent in Maine, New Hampshire, and Vermont (table 1). Nearly all rural, domestic, and small-community water systems obtain water from wells that are, in comparison with other sources, the safest and the least expensive to install and maintain. Where water demand is great-in the urban areas of New York, Connecticut, Massachusetts, and Rhode Island-sophisticated reservoir, pipeline, and purification systems are economically feasible and are needed to meet demands. Surface water is the principal source of supply in these four States, and ground water was used to supply only 24 to 35 percent of their population during 1980 (table 1).

A prelanding assessment of the ice table depth and ground ice characteristics in Martian permafrost at the Phoenix landing site

USGS Publications Warehouse

Mellon, M.T.; Boynton, W.V.; Feldman, W.C.; Arvidson, R. E.; Titus, Joshua T.N.; Bandfield, L.; Putzig, N.E.; Sizemore, H.G.

2009-01-01

We review multiple estimates of the ice table depth at potential Phoenix landing sites and consider the possible state and distribution of subsurface ice. A two-layer model of ice-rich material overlain by ice-free material is consistent with both the observational and theoretical lines of evidence. Results indicate ground ice to be shallow and ubiquitous, 2-6 cm below the surface. Undulations in the ice table depth are expected because of the thermodynamic effects of rocks, slopes, and soil variations on the scale of the Phoenix Lander and within the digging area, which can be advantageous for analysis of both dry surficial soils and buried ice-rich materials. The ground ice at the ice table to be sampled by the Phoenix Lander is expected to be geologically young because of recent climate oscillations. However, estimates of the ratio of soil to ice in the ice-rich subsurface layer suggest that that the ice content exceeds the available pore space, which is difficult to reconcile with existing ground ice stability and dynamics models. These high concentrations of ice may be the result of either the burial of surface snow during times of higher obliquity, initially high-porosity soils, or the migration of water along thin films. Measurement of the D/H ratio within the ice at the ice table and of the soil-to-ice ratio, as well as imaging ice-soil textures, will help determine if the ice is indeed young and if the models of the effects of climate change on the ground ice are reasonable. Copyright 2008 by the American Geophysical Union.

Sequence stratigraphic distribution of coaly rocks: Fundamental controls and paralic examples

USGS Publications Warehouse

Bohacs, K.; Suter, J.

1997-01-01

Significant volumes of terrigenous organic matter can be preserved to form coals only when and where the overall increase in accommodation approximately equals the production rate of peat. Accommodation is a function of subsidence and base level. For mires, base level is very specifically the groundwater table. In paralic settings, the groundwater table is strongly controlled by sea level and the precipitation/evaporation ratio. Peat accumulates over a range of rates, but always with a definite maximum rate set by original organic productivity and space available below depositional base level (groundwater table). Below a threshold accommodation rate (nonzero), no continuous peats accumulate, due to falling or low groundwater table, sedimentary bypass, and extensive erosion by fluvial channels. This is typical of upper highstand, lowstand fan, and basal lowstand-wedge systems tracts. Higher accommodation rates provide relatively stable conditions with rising groundwater tables. Mires initiate and thrive, quickly filling local accommodation vertically and expanding laterally, favoring accumulation of laterally continuous coals in paralic zones within both middle lowstand and middle highstand systems tracts. If the accommodation increase balances or slightly exceeds organic productivity, mires accumulate peat vertically, yielding thicker, more isolated coals most likely during of late lowstand-early transgressive and late transgressive-early highstand periods. At very large accommodation increases, mires are stressed and eventually inundated by clastics or standing water (as in middle transgressive systems tracts). These relations should be valid for mires in all settings, including alluvial, lake plain, and paralic. The tie to sea level in paralic zones depends on local subsidence, sediment supply, and groundwater regimes. These concepts are also useful for investigating the distribution of seal and reservoir facies in nonmarine settings.

Disposal of high-level nuclear waste above the water table in arid regions

USGS Publications Warehouse

Roseboom, Eugene H.

1983-01-01

Locating a repository in the unsaturated zone of arid regions eliminates or simplifies many of the technological problems involved in designing a repository for operation below the water table and predicting its performance. It also offers possible accessibility and ease of monitoring throughout the operational period and possible retrieval of waste long after. The risks inherent in such a repository appear to be no greater than in one located in the saturated zone; in fact, many aspects of such a repository's performance will be much easier to predict and the uncertainties will be reduced correspondingly. A major new concern would be whether future climatic changes could produce significant consequences due to possible rise of the water table or increased flux of water through the repository. If spent fuel were used as a waste form, a second new concern would be the rates of escape of gaseous iodine-129 and carbon-14 to the atmosphere.

77 FR 10695 - Federal Housing Administration (FHA) Risk Management Initiatives: Revised Seller Concessions

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-23

... in Tables A and B. Table D--Borrower Closing Costs and Seller Concessions Descriptive Statistics by... accuracy of the statistical data illustrating the correlation between higher seller concessions and an...

Simulation of advective flow under steady-state and transient recharge conditions, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, Donald A.; Masterson, John P.

2003-01-01

The U.S. Geological Survey has developed several ground-water models in support of an investigation of ground-water contamination being conducted by the Army National Guard Bureau at Camp Edwards, Massachusetts Military Reservation on western Cape Cod, Massachusetts. Regional and subregional steady-state models and regional transient models were used to (1) improve understanding of the hydrologic system, (2) simulate advective transport of contaminants, (3) delineate recharge areas to municipal wells, and (4) evaluate how model discretization and time-varying recharge affect simulation results. A water-table mound dominates ground-water-flow patterns. Near the top of the mound, which is within Camp Edwards, hydraulic gradients are nearly vertically downward and horizontal gradients are small. In downgradient areas that are further from the top of the water-table mound, the ratio of horizontal to vertical gradients is larger and horizontal flow predominates. The steady-state regional model adequately simulates advective transport in some areas of the aquifer; however, simulation of ground-water flow in areas with local hydrologic boundaries, such as ponds, requires more finely discretized subregional models. Subregional models also are needed to delineate recharge areas to municipal wells that are inadequately represented in the regional model or are near other pumped wells. Long-term changes in recharge rates affect hydraulic heads in the aquifer and shift the position of the top of the water-table mound. Hydraulic-gradient directions do not change over time in downgradient areas, whereas they do change substantially with temporal changes in recharge near the top of the water-table mound. The assumption of steady-state hydraulic conditions is valid in downgradient area, where advective transport paths change little over time. In areas closer to the top of the water-table mound, advective transport paths change as a function of time, transient and steady-state paths do not coincide, and the assumption of steady-state conditions is not valid. The simulation results indicate that several modeling tools are needed to adequately simulate ground-water flow at the site and that the utility of a model varies according to hydrologic conditions in the specific areas of interest.

Air Sparging Versus Gas Saturated Water Injection for Remediation of Volatile LNAPL in the Borden Aquifer

NASA Astrophysics Data System (ADS)

Barker, J.; Nelson, L.; Doughty, C.; Thomson, N.; Lambert, J.

2009-05-01

In the shallow, rather homogeneous, unconfined Borden sand aquifer, field trials of air sparging (Tomlinson et al., 2003) and pulsed air sparging (Lambert et al., 2009) have been conducted, the latter to remediate a residual gasoline source emplaced below the water table. As well, a supersaturated (with CO2) water injection (SWI) technology, using the inVentures inFusion system, has been trialed in two phases: 1. in the uncontaminated sand aquifer to evaluate the radius of influence, extent of lateral gas movement and gas saturation below the water table, and 2. in a sheet pile cell in the Borden aquifer to evaluate the recovery of volatile hydrocarbon components (pentane and hexane) of an LNAPL emplaced below the water table (Nelson et al., 2008). The SWI injects water supersaturated with CO2. The supersaturated injected water moves laterally away from the sparge point, releasing CO2 over a wider area than does gas sparging from a single well screen. This presentation compares these two techniques in terms of their potential for remediating volatile NAPL components occurring below the water table in a rather homogeneous sand aquifer. Air sparging created a significantly greater air saturation in the vicinity of the sparge well than did the CO2 system (60 percent versus 16 percent) in the uncontaminated Borden aquifer. However, SWI pushed water, still supersaturated with CO2, up to about 2.5 m from the injection well. This would seem to provide a considerable advantage over air sparging from a point, in that gas bubbles are generated at a much larger radius from the point of injection with SWI and so should involve additional gas pathways through a residual NAPL. Overall, air sparging created a greater area of influence, defined by measurable air saturation in the aquifer, but air sparging also injected about 12 times more gas than was injected in the SWI trials. The pulsed air sparging at Borden (Lambert et al.) removed about 20 percent (4.6 kg) of gasoline hydrocarbons, mainly pentane and hexane, from the residual gasoline via sparging. A similar mass was estimated to have been removed by aerobic biodegradation. The extent of volatile recovery needs to be better defined and so post-sparging coring and analysis of residual LNAPL is underway. Impressively, the second SWI trial recovered more than 60 percent of the pentane-hexane from the NAPL. In both field experiments there was potential for minor additional recovery if the system had been operated longer. Comparison of efficiency of the pulsed air sparging and SWI systems is difficult in that the initial LNAPL residuals have different chemistry, but similar distribution, different volumes of gas were used, and biodegradation accounted for a significant removal of hydrocarbons only in the air sparging system. The SWI trial recovered an impressive portion of the volatile LNAPL, while using considerably less gas than the air sparging system, but the SWI delivery system was both more complex and more expensive than the air sparging system. Additional trials are underway in more complex aquifers to further assess the performance of the SWI technology, including costs and practical limitations.

Interactions of diffuse and focused allogenic recharge in an eogenetic karst aquifer (Florida, USA)

NASA Astrophysics Data System (ADS)

Langston, Abigail L.; Screaton, Elizabeth J.; Martin, Jonathan B.; Bailly-Comte, Vincent

2012-06-01

The karstic upper Floridan aquifer in north-central Florida (USA) is recharged by both diffuse and allogenic recharge. To understand how recharged water moves within the aquifer, water levels and specific conductivities were monitored and slug tests were conducted in wells installed in the aquifer surrounding the Santa Fe River Sink and Rise. Results indicate that diffuse recharge does not mix rapidly within the aquifer but instead flows horizontally. Stratification may be aided by the high matrix porosity of the eogenetic karst aquifer. Purging wells for sample collection perturbed conductivity for several days, reflecting mixing of the stratified water and rendering collection of representative samples difficult. Interpretive numerical simulations suggest that diffuse recharge impacts the intrusion of allogenic water from the conduit by increasing hydraulic head in the surrounding aquifer and thereby reducing influx to the aquifer from the conduit. In turn, the increase of head within the conduits affects flow paths of diffuse recharge by moving newly recharged water vertically as the water table rises and falls. This movement may result in a broad vertical zone of dissolution at the water table above the conduit system, with thinner and more focused water-table dissolution at greater distance from the conduit.

Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen

USGS Publications Warehouse

Chivers, M.R.; Turetsky, M.R.; Waddington, J.M.; Harden, J.W.; McGuire, A.D.

2009-01-01

Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen located just outside the Bonanza Creek Experimental Forest in interior Alaska. The drought (lowered water table position) treatment was a weak sink or small source of atmospheric CO2 compared to the moderate atmospheric CO2 sink at our control. This change in net ecosystem exchange was due to lower gross primary production and light-saturated photosynthesis rather than increased ecosystem respiration. The flooded (raised water table position) treatment was a greater CO2 sink in 2006 due largely to increased early season gross primary production and higher light-saturated photosynthesis. Although flooding did not have substantial effects on rates of ecosystem respiration, this water table treatment had lower maximum respiration rates and a higher temperature sensitivity of ecosystem respiration than the control plot. Surface soil warming increased both ecosystem respiration and gross primary production by approximately 16% compared to control (ambient temperature) plots, with no net effect on net ecosystem exchange. Results from this rich fen manipulation suggest that fast responses to drought will include reduced ecosystem C storage driven by plant stress, whereas inundation will increase ecosystem C storage by stimulating plant growth. ?? 2009 Springer Science+Business Media, LLC.

Relation between ground water and surface water in Brandywine Creek basin, Pennsylvania

USGS Publications Warehouse

Olmsted, F.H.; Hely, A.G.

1962-01-01

The relation between ground water and surface water was studied in Brandywine Creek basin, an area of 287 square miles in the Piedmont physiographic province in southeastern Pennsylvania. Most of the basin is underlain by crystalline rocks that yield only small to moderate supplies of water to wells, but the creek has an unusually well-sustained base flow. Streamflow records for the Chadds Ford, Pa., gaging station were analyzed; base flow recession curves and hydrographs of base flow were defined for the calendar years 1928-31 and 1952-53. Water budgets calculated for these two periods indicate that about two-thirds of the runoff of Brandywine Creek is base flow--a significantly higher proportion of base flow than in streams draining most other types of consolidated rocks in the region and almost as high as in streams in sandy parts of the Coastal Plain province in New Jersey and Delaware. Ground-water levels in 16 observation wells were compared with the base flow of the creek for 1952-53. The wells are assumed to provide a reasonably good sample of average fluctuations of the water table and its depth below the land surface. Three of the wells having the most suitable records were selected as index wells to use in a more detailed analysis. A direct, linear relation between the monthly average ground-water stage in the index wells and the base flow of the creek in winter months was found. The average ground-water discharge in the basin for 1952-53 was 489 cfs (316 mgd), of which slightly less than one-fourth was estimated to be loss by evapotranspiration. However, the estimated evapotranspiration from ground water, and consequently the estimated total ground-water discharge, may be somewhat high. The average gravity yield (short-term coefficient of storage) of the zone of water-table fluctuation was calculated by two methods. The first method, based on the ratio of change in ground-water storage as calculated from a witner base-flow recession curve is seasonal change in ground-water stage in the observation wells, gave values of about 7 percent using 16 wells) and 7 1/2 percent (using 3 index wells). The second method, in which the change in ground water storage is based on a hypothetical base-flow recession curve (derived from the observed linear relation between ground-water stage in the index wells and base flow), gave a value of about 10 1/2 percent. The most probable value of gravity yield is between 7 1/2 and 10 percent, but this estimate may require modification when more information on the average magnitude of water-table fluctuation and the sources of base flow of the creek become available. Rough estimates were made of the average coefficient of transmissibility of the rocks in the basin by use of the estimated total ground-water discharge for the period 1952-53, approximate values of length of discharge areas, and average water-table gradients adjacent to the discharge areas. The estimated average coefficient of transmissibility for 1952-53 is roughly 1,000 gpd per foot. The transmissibility is variable, decreasing with decreasing ground-water stage. The seeming inconsistency between the small to moderate ground-water yield to wells and the high yield to streams is explained in terms of the deep permeable soils, the relatively high gravity yield of the zone of water-table fluctuation, the steep water-table gradients toward the streams, the relatively low transmissibility of the rocks, and the rapid decreases in gravity yield below the lower limit of water-table fluctuation. It is concluded that no simple relation exists between the amount of natural ground-water discharge in an area and all the proportion of this discharge that can be diverted to wells.

Long-Term Changes In The Shallow Water Table In A Mining Area: The Lubin-Glogow Copper Region, Southwestern Poland

NASA Astrophysics Data System (ADS)

Bochenska, T.; Limisiewicz, P.; Loprawski, L.

1995-03-01

In regions of intense mining, shortages of water are common. Increased water demand is normally associated with industry in mining areas, and mine unwatering has negative effects on the natural groundwater balance. The study area occupies 3,300 square kilometers within the copper mining region of Lubin-Glogow, southwestern Poland. Pumping of groundwater to drain mines has created a cone of depression that underlies 2,500 square kilometers. The lowering of potentiometric surfaces has occurred in deep aquifers, which are isolated from the surface by thick confining units (loams and clays). Changes of hydraulic head in the shallow aquifer have not previously been observed. In this study, the authors analyzed the water-table changes in the shallow aquifer. The statistical analysis of the water table was based on two sets of water-level measurements in about 1,200 farm wells during dry seasons. The first set was done in the fall of 1986, the second in the fall of 1991. In addition to these measurements, multi-seasonal observations were made by the mining survey in several tens of wells. During five years, the head declined an average of 0.4 meter. Locally, the lowering was as great as five meters. The regional decline of head resulted in a loss of water resources about 2×108 cubic meters. Regionally, this loss is not directly related to the dewatering of copper mines. Locally, however, mining activity strongly influences the water table. The general trend of the decline is probably an effect of decreasing precipitation.

Peat characteristics and groundwater geochemistry of calcareous fens in the Minnesota River Basin, U.S.A

USGS Publications Warehouse

Almendinger, J.E.; Leete, J.H.

1998-01-01

. Calcareous fens in Minnesota are spring-seepage peatlands with a distinctive flora of rare calciphilic species. Peat characteristics and groundwater geochemistry were determined for six calcareous fens in the Minnesota River Basin to better understand the physical structure and chemical processes associated with stands of rare vegetation. Onset of peat accumulation in three of the fens ranged from about 4,700 to 11,000 14C yrs BP and probably resulted from a combination of climate change and local hydrogeologic conditions. Most peat cores had a carbonate-bearing surface zone with greater than 10% carbonates (average 27%, dry wt basis), an underlying carbonate-depleted zone with 10% or less carbonates (average 4%), and a carbonate-bearing lower zone again with greater than 10% carbonates (average 42%). This carbonate zonation was hypothesized to result from the effect of water-table level on carbonate equilibria: carbonate precipitation occurs when the water table is above a critical level, and carbonate dissolution occurs when the water table is lower. Other processes that changed the major ion concentrations in upwelling groundwater include dilution by rain water, sulfate reduction or sulfide oxidation, and ion adsorption or exchange. Geochemical modeling indicated that average shallow water in the calcareous fens during the study period was groundwater mixed with about 6 to 13% rain water. Carbonate precipitation in the surface zone of calcareous fens could be decreased by a number of human activities, especially those that lower the water table. Such changes in shallow water geochemistry could alter the growing conditions that apparently sustain rare fen vegetation.

Spectral detection of near-surface moisture content and water-table position in northern peatland ecosystems

Treesearch

Karl M. Meingast; Michael J. Falkowski; Evan S. Kane; Lynette R. Potvin; Brian W. Benscoter; Alistair M.S. Smith; Laura L. Bourgeau-Chavez; Mary Ellen Miller

2014-01-01

Wildland fire occurrence has been increasing in peatland ecosystems during recent decades. As such, there is a need for broadly applicable tools to detect and monitor controls on combustion such as surface peat moisture and water-table position. A field portable spectroradiometer was used to measure surface reflectance of two Sphagnum moss-dominated...

Understanding drivers of peatland extracellular enzyme activity in the PEATcosm experiment: mixed evidence for enzymic latch hypothesis

Treesearch

Karl J. Romanowicz; Evan S. Kane; Lynette R. Potvin; Aleta L. Daniels; Randy Kolka; Erik A. Lilleskov

2015-01-01

Aims. Our objective was to assess the impacts of water table position and plant functional groups on peatland extracellular enzyme activity (EEA) framed within the context of the enzymic latch hypothesis. Methods. We utilized a full factorial experiment with 2 water table (WT) treatments (high and low) and 3 plant functional...

Interactive plant functional group and water table effects on decomposition and extracellular enzyme activity in Sphagnum peatlands

Treesearch

Magdalena M. Wiedermann; Evan S. Kane; Lynette R. Potvin; Erik A. Lilleskov

2017-01-01

Peatland decomposition may be altered by hydrology and plant functional groups (PFGs), but exactly how the latter influences decomposition is unclear, as are potential interactions of these factors.We used a factorial mesocosm experiment with intact 1 m3 peat monoliths to explore how PFGs (sedges vs Ericaceae) and water table level individually...

Tank 241-B-108, cores 172 and 173 analytical results for the final report

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

Nuzum, J.L., Fluoro Daniel Hanford

1997-03-04

The Data Summary Table (Table 3) included in this report compiles analytical results in compliance with all applicable DQOS. Liquid subsamples that were prepared for analysis by an acid adjustment of the direct subsample are indicated by a `D` in the A column in Table 3. Solid subsamples that were prepared for analysis by performing a fusion digest are indicated by an `F` in the A column in Table 3. Solid subsamples that were prepared for analysis by performing a water digest are indicated by a I.wl. or an `I` in the A column of Table 3. Due to poormore » precision and accuracy in original analysis of both Lower Half Segment 2 of Core 173 and the core composite of Core 173, fusion and water digests were performed for a second time. Precision and accuracy improved with the repreparation of Core 173 Composite. Analyses with the repreparation of Lower Half Segment 2 of Core 173 did not show improvement and suggest sample heterogeneity. Results from both preparations are included in Table 3.« less

Ground-water age and atmospheric tracers: Simulation studies and analysis of field data from the Mirror Lake site, New Hampshire

USGS Publications Warehouse

Goode, Daniel J.

1998-01-01

The use of environmental tracers in characterization of ground-water systems is investigated through mathematical modeling of ground-water age and atmospheric tracer transport, and by a field study at the Mirror Lake site, New Hampshire. Theory is presented for modeling ground-water age using the advective-dispersive transport equation. The transport equation includes a zero-order source of unit strength, corresponding to the rate of aging, and can accommodate matrix diffusion and other exchange processes. The effect of temperature fluctuations and layered soils on transport of atmospheric gases to the water table is investigated using a one-dimensional numerical model of chlorofluorocarbon (CFC-11) transport. The nonlinear relation between temperature and Henry's Law coefficient (reflecting air/water phase partitioning) can cause the apparent recharge temperature to be elevated above the annual mean temperature where the water table is shallow. In addition, fine-grained soils can isolate the air phase in the unsaturated zone from the atmosphere. At the USGS' Mirror Lake, New Hampshire fractured-rock research site CFC concentrations near the water table are depleted where dissolved oxygen is low. CFC-11 and CFC-113 are completely absent under anaerobic conditions, while CFC-12 is as low as one-third of modern concentrations. Anaerobic biodegradation apparently consumes CFC's near the water table at this site. One area of active degradation appears to be associated with streamflow loss to ground water. Soil gas concentrations are generally close to atmospheric levels, although some spatial correlation is observed between depleted concentrations of CFC-11 and CFC-113 in soil gas and water-table samples. Results of unsaturated-zone monitoring indicate that recharge occurs throughout the year in the watershed, even during summer evapotranspiration periods, and that seasonal temperature fluctuations occur as much as 5 meters below land surface. Application of ground-water age and CFC-11 transport models to the large-scale ground-water system at Mirror Lake illustrates the similarities between age and chemical transport. Generally, bedrock porosities required to match observed apparent ages from CFC concentrations are high relative to porosities measured on cores. Although matrix diffusion has no effect on steady-state age, it can significantly reduce CFC concentrations in fractured rock in which the effective porosity is low.

Seasonal changes in Sphagnum peatland testate amoeba communities along a hydrological gradient.

PubMed

Marcisz, Katarzyna; Lamentowicz, Lukasz; Słowińska, Sandra; Słowiński, Michał; Muszak, Witold; Lamentowicz, Mariusz

2014-10-01

Testate amoebae are an abundant and functionally important group of protists in peatlands, but little is known about the seasonal patterns of their communities. We investigated the relationships between testate amoeba diversity and community structure and water table depth and light conditions (shading vs. insolation) in a Sphagnum peatland in Northern Poland (Linje mire) in spring and summer 2010. We monitored the water table at five sites across the peatland and collected Sphagnum samples in lawn and hummock micro-sites around each piezometer, in spring (3 May) and mid-summer (6 August) 2010. Water table differed significantly between micro-sites and seasons (Kruskal-Wallis test, p=0.001). The community structure of testate amoebae differed significantly between spring and summer in both hummock and lawn micro-sites. We recorded a small, but significant drop in Shannon diversity, between spring and summer (1.76 vs. 1.72). Strongest correlations were found between testate amoeba communities and water table lowering and light conditions. The relative abundance of mixotrophic species Hyalosphenia papilio, Archerella flavum and of Euglypha ciliata was higher in the summer. Copyright © 2014 Elsevier GmbH. All rights reserved.

Impact of Preservation of Subsoil Water Act on Groundwater Depletion: The Case of Punjab, India.

PubMed

Tripathi, Amarnath; Mishra, Ashok K; Verma, Geetanjali

2016-07-01

Indian states like Punjab and Haryana, epicenters of the Green Revolution, are facing severe groundwater shortages and falling water tables. Recognizing it as a serious concern, the Government of Punjab enacted the Punjab Preservation of Subsoil Water Act in 2009 (or the 2009 act) to slow groundwater depletion. The objective of this study is to assess the impact of this policy on groundwater depletion, using panel data from 1985 to 2011. Results from this study find a robust effect of the 2009 act on reducing groundwater depletion. Our models for pre-monsoon, post-monsoon, and overall periods of analysis find that since implementation of the 2009 act, groundwater tables have improved significantly. Second, our study reveals that higher shares of tube wells per total cropped area and increased population density have led to a significant decline in the groundwater tables. On the other hand, rainfall and the share of area irrigated by surface water have had an augmenting effect on groundwater resources. In the two models, pre-monsoon and post-monsoon, this study shows that seasonality plays a key role in determining the groundwater table in Punjab. Specifically, monsoon rainfall has a very prominent impact on groundwater.

Water-quality and ground-water-level trends, 1990-99, and data collected from 1995 through 1999, East Mountain area, Bernalillo County, central New Mexico

USGS Publications Warehouse

Rankin, D.R.

2000-01-01

Bernalillo County officials recognize the importance of monitoring water quality and ground-water levels in rapidly developing areas. For this reason, water-quality and ground-water- level data were collected from 87 wells, 3 springs, and the Ojo Grande Acequia in the east mountain area of Bernalillo County between January 1990 and June 1999. The water samples were analyzed for selected nutrient species; total organic carbon; major dissolved constituents; methylene blue active substances; and dissolved arsenic. Analytical results were used to compute hardness, sodium adsorption ratio, and dissolved solids. Specific conductance, pH, air and water temperature, alkalinity, and dissolved oxygen were measured in the field at the time of sample collection. Ground-water levels were measured at the time of sample collection. From January 1990 through June 1993, water-quality and ground- water-level data were collected monthly from an initial set of 20 wells; these data were published in a 1995 report. During 1995, water samples and ground-water-level data were collected and analyzed from the initial set of 20 wells and from an additional 31 wells, 2 springs, and the Ojo Grande Acequia; these data were published in a 1996 report. Additional water-quality and ground-water-level data have been collected from sites in the east mountain area: 34 wells and the acequia during 1997, 14 wells and 1 spring during 1998, and 6 wells during 1999. Water-quality and ground- water-level data collected in the east mountain area during 1995 through 1999 are presented in tables. In addition, temporal trends for ground-water levels, concentrations of total and dissolved nitrite plus nitrate, concentrations of dissolved chloride, and specific conductance are presented for 20 selected wells in water-quality and water- level hydrographs.

Experimental response of Salix cuttings to sudden water table changing dynamics

NASA Astrophysics Data System (ADS)

Gorla, L.; Signarbieux, C.; Turberg, P.; Buttler, A.; Perona, P.

2013-12-01

Hydropower production, agriculture and other human activities change the natural flow regime of rivers, in turn impacting the riparian environment. Inadequate flow rules (e.g., minimal or residual flows) reflecting our limited understanding of eco-hydrological processes have thus been applied since decades. The main challenge for an eco-sustainable water management is to quantify the effects of flow regulation on channel morphodynamics and biological processes. We present a controlled laboratory experiment to investigate riparian vegetation (Salix Viminalis) response to forced water table changing dynamics, from one water regime to another, in a temperate region (Switzerland). Three synthetic flow regimes have been simulated and applied to three batteries of Salix cuttings (60 in total) growing outdoor within plastic pots, each about 1 meter tall. After an initial period where all pots undergone the same oscillations in order to uniform the plants initial conditions, the experiment started, and the water dynamic was changed for two out of three batteries. In particular, one treatment simulated a minimal flow policy, which drastically impacts the low and the medium-low components of the hydrograph, but not the extremes. The other treatment reproduced only the low frequencies corresponding to the seasonal trend of the natural flow regime, still applied on the third battery. Cuttings transitory response dynamics has been quantified by continuous sap flow and water potential measurements, and by regularly collecting growth parameters, as well as leaves photosynthesis, fluorescence, and pictures of each plant. At the end of the experiment, all cuttings were carefully removed and the both above and below ground biomass analyzed in detail. Particularly, the 3D root structure was obtained by High Resolution Computer Tomography. Our analyses reveal a clear dependence between roots distribution and water regime reflecting the need for adaptation, which are also in agreement with field observations of Pasquale et al. (2012, in press). In particular, an initial strong difference in terms of stress and growth performances was then followed by a later adjustment in the roots system, notably detected from tomographic images. Roots tropic response resulted in spatial reallocation, which likely allowed survivors to adapt to new conditions. Macroscopic effects in terms of growth parameters at weekly time step have found correspondence at higher time resolution in terms of sap flow and stem pressure, strengthening our results interpretation. Other interesting effects detected by sap flow meters and psychrometers in the transition time, even if coherent to water regimes, have not led to macroscopic effects. A discussion with data from a parallel field installation along the Thur River (Switzerland) is also made. REFERENCES - Pasquale et al., Effects of streamflow variability on the vertical root density distribution of willow cutting experiments, Ecological Engineering,2011, 10.1016/j.ecoleng.2012.12.002 - Pasquale et al., Above and below-ground Salix dynamics in response to river processes, Hydrological Processes., in press, 10.1002/hyp.9993

The National Study of Water Management during Drought: A Research Assessment

DTIC Science & Technology

1991-08-01

Planning: June 1990 53 Table 11-6 Effectiveness of Drought Response Measures Implemented in Various Locations 61 Table 11-7 The Structure of Existing...Status of Drought Planning June 1990 52 Figure III-I The Short Term Effects of Severe Drought on the Aggregate Economy 72 Figure 111-2 Rationing in the...Market for Water 73 Figure 111-3 Soil-Water-Plant System 83 Figure 111-4 Farm System 87 Figure 1II-5 Economic Effects of Drought on Navigation 98

Self-potential monitoring of water flux at the HOBE agricultural site, Voulund, Denmark

NASA Astrophysics Data System (ADS)

Jougnot, D.; Linde, N.; Looms, M. C.

2013-12-01

The self-potential (SP) method is of interest in hydrology and environmental sciences because of its non-invasive nature and its sensitivity to flow and transport processes in the subsurface. The contribution to the SP signal by water flux is referred to as the streaming potential and is due to the presence of an electrical double layer at the mineral-pore water interface. When water flows through the pore, it gives rise to a streaming current and a resulting measurable electrical voltage between non-polarizable electrodes placed at different locations. This electrokinetic behavior is well understood in water saturated porous media, but the best way to model streaming currents under partial saturation is still under discussion. To better understand SP data within the vadose zone, we conducted field-based monitoring of the vertical distribution of the SP signal following different hydrologic events. The investigations were carried out at the Voulund agricultural test site that is part of the Danish hydrological observatory, HOBE, located in the Skjern river catchment (Denmark) in the middle of a cultivated area. It has been instrumented since 2010 to monitor suction, water content and temperature down to a depth of 3 m, together with meteorological variables and repeated geophysical campaigns (cross borehole electrical resistivity tomography and ground penetrating radar). In July 2011, we installed 15 non-polarizable electrodes at 10 depths within the vadose zone (from 0.25 to 3.10 m) and a reference electrode below the water table (7.30 m). More than 2 years of data acquired at a measurement period of 5 minutes are now available with periods indicative of various hydrologic events, such as natural infiltration, water table rises and a high salinity tracer test. We performed wavelet-based signal analysis and investigated the wavelet coherency of the SP data with other measurement variables. The wavelet coherency analysis displays an anti-correlation between SP and water content at high frequencies (periods smaller than 1 day) and between SP and temperature at lower frequencies. For the high salinity tracer test, the continuous wavelet power spectra of the SP time series indicate that most signal energy is initially located in the higher frequencies at the top of the soil profile and later at lower frequencies at depth as the plume migrates downwards. We use a numerical model of the test site to simulate water fluxes, ionic transport and SP during different hydrological events. The first simulation results compare fairly well to the measured data. These initial results will serve as starting point for a detailed assessment of the value of SP data in vadose zone hydrology, particularly as a tool for in situ monitoring of water flux.

Factors influencing CO2 and CH4 emissions from coastal wetlands in the Liaohe Delta, northeast China

USGS Publications Warehouse

Olsson, Linda; Ye, Siyuan; Yu, Xueyang; Wei, Mengjie; Krauss, Ken W.; Brix, Hans

2015-01-01

Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4sources emitting 1.2–6.1 g CH4 m−2 y−1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2. The main controlling factors for the CH4 emissions were water table, temperature and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1 mg CH4 m−2 h) at soil temperatures <18 °C. At salinity levels > 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m−2 h−1) probably because methanogens were outcompeted by sulphate reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.

Altitude and configuration of the potentiometric surface in the Triassic sandstones and shales, northeastern Chester County, Pennsylvania, September 1987 through January 1988

USGS Publications Warehouse

Senior, Lisa A.; Garges, John A.

1989-01-01

The altitude of the water levels in the Triassic sandstones and shales in northeastern Chester County is shown on a map at a scale of 1:24,000. The map is based on water levels in 173 non-pumping drilled and dug wells measured in 1956 and 1965, and on the altitude of two springs that were flowing in November and December 1987. Water level altitudes are contoured at an interval of 20 ft. The surface defined by the contoured water levels may approximately represent the water table. Water table altitudes range from 379 ft to less than 80 ft above sea level. (USGS)

Vertical Gradients in Water Chemistry and Age in the Southern High Plains Aquifer, Texas, 2002

USGS Publications Warehouse

McMahon, P.B.; Böhlke, J.K.; Lehman, T.M.

2004-01-01

The southern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of New Mexico and Texas. Despite the aquifer's importance to the overall economy of the southern High Plains, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S. Geological Survey's National Water-Quality Assessment Program, water samples from nested, short-screen monitoring wells installed in the southern High Plains aquifer at two locations (Castro and Hale Counties, Texas) were analyzed for field parameters, major ions, nutrients, trace elements, dissolved organic carbon, pesticides, stable and radioactive isotopes, and dissolved gases to evaluate vertical gradients in water chemistry and age in the aquifer. Tritium measurements indicate that recent (post-1953) recharge was present near the water table and that deeper water was recharged before 1953. Concentrations of dissolved oxygen were largest (2.6 to 5.6 milligrams per liter) at the water table and decreased with depth below the water table. The smallest concentrations were less than 0.5 milligram per liter. The largest major-ion concentrations generally were detected at the water table because of the effects of overlying agricultural activities, as indicated by postbomb tritium concentrations and elevated nitrate and pesticide concentrations at the water table. Below the zone of agricultural influence, major-ion concentrations exhibited small increases with depth and distance along flow paths because of rock/water interactions and mixing with water from the underlying aquifer in rocks of Cretaceous age. The concentration increases primarily were accounted for by dissolved sodium, bicarbonate, chloride, and sulfate. Nitrite plus nitrate concentrations at the water table were 2.0 to 6.1 milligrams per liter as nitrogen, and concentrations substantially decreased with depth in the aquifer to a maximum concentration of 0.55 milligram per liter as nitrogen. Dissolved-gas and nitrogen-isotope data from the deep wells in Castro County indicate that denitrification occurred in the aquifer, removing 74 to more than 97 percent of the nitrate originally present in recharge. There was no evidence of denitrification in the deep part of the aquifer in Hale County. After correcting for denitrification effects, the background concentration of nitrate in water recharged before 1953 ranged from 0.4 to 3.2 milligrams per liter as nitrogen, with an average of 1.6 milligrams per liter as nitrogen. The d15N composition of background nitrate at the time of recharge was estimated to range from 9.6 to 12.3 per mil. Mass-balance models indicate that the decreases in dissolved oxygen and nitrate concentrations and small increases in major-ion concentrations along flow paths can be accounted for by small amounts of silicate-mineral and calcite dissolution; SiO2, goethite, and clay-mineral precipitation; organic-carbon and pyrite oxidation; denitrification; and cation exchange. Mass-balance models for some wells also required mixing with water from the underlying aquifer in rocks of Cretaceous age to achieve mole and isotope balances. Carbon mass transfers identified in the models were used to adjust radiocarbon ages of water samples recharged before 1953. Adjusted radiocarbon ages ranged from less than 1,000 to 9,000 carbon-14 years before present. Radiocarbon ages were more sensitive to uncertainties in the carbon-14 content of recharge than uncertainties in carbon mass transfers, leading to 1-sigma uncertainties of about ?2,000 years in the adjusted ages. Despite these relatively large uncertainties in adjusted radiocarbon ages, it appears that deep water in the aquifer was considerably older (at least 1,000 years) than water near the water table. There was essentially no change in ground-water age with depth in deeper parts of the aquifer, indicating that water in that

A Hydraulic Nexus between Geographically Isolated Wetlands and Downstream Water Bodies

NASA Astrophysics Data System (ADS)

Mclaughlin, D. L.; Kaplan, D. A.; Cohen, M. J.

2014-12-01

Geographic isolation does not imply hydrological isolation; indeed, local groundwater exchange between geographically isolated wetlands (GIWs) and surrounding uplands may yield important controls on regional hydrology. Differences in specific yield (Sy) between aquifers and inundated GIWs drive differences in water level responses to atmospheric fluxes, leading to frequent reversals in hydraulic gradients that cause GIWs to act as both groundwater sinks and sources. When distributed across the landscape, these reversals in local groundwater fluxes are predicted to collectively buffer the surficial aquifer and its regulation of baseflow delivery, a process we refer to as landscape hydrologic capacitance. To test this hypothesis, we integrated models of daily soil moisture, upland water table, and wetland stage dynamics to simulate hydrology of a low-relief landscape with GIWs. Simulations explored the influences of cumulative wetland area, individual wetland size, climate, and soil texture on water table and baseflow variation. Increasing cumulative wetland area and decreasing individual wetland size reduced water table variation and the frequency of extremely shallow and deep water tables. This buffering effect extended to baseflow deliveries, decreasing the standard deviation of daily baseflow by as much as 50%. For the same total wetland area, landscapes with fewer (i.e., larger) wetlands exhibited markedly lower hydrologic capacitance than those with more (i.e., smaller) wetlands, highlighting the important role of small GIWs in regulating regional hydrology. Recent U.S. Supreme Court rulings have limited federal protections for GIWs except where a "significant nexus" to a navigable water body is demonstrated. Our results suggest that GIWs regulate downstream baseflow, even where water in GIWs may never physically reach downstream systems, providing a significant "hydraulic" nexus to distant water bodies.

Isotopic Survey of Lake Davis and the Local Groundwater

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

Ridley, M N; Moran, J E; Singleton, M J

2007-08-21

In September 2007, California Fish and Game (CAFG) plans to eradicate the northern pike from Lake Davis. As a result of the eradication treatment, local residents have concerns that the treatment might impact the local groundwater quality. To address the concerns of the residents, Lawrence Livermore National Laboratory (LLNL) recommended measuring the naturally occurring stable oxygen isotopes in local groundwater wells, Lake Davis, and the Lake Davis tributaries. The purpose of these measurements is to determine if the source of the local groundwater is either rain/snowmelt, Lake Davis/Big Grizzly Creek water or a mixture of Lake Davis/Big Grizzly Creek andmore » rain/snowmelt. As a result of natural evaporation, Lake Davis and the water flowing into Big Grizzly Creek are naturally enriched in {sup 18}oxygen ({sup 18}O), and if a source of a well's water is Lake Davis or Big Grizzly Creek, the well water will contain a much higher concentration of {sup 18}O. This survey will allow for the identification of groundwater wells whose water source is Lake Davis or Big Grizzly Creek. The results of this survey will be useful in the development of a water-quality monitoring program for the upcoming Lake Davis treatment. LLNL analyzed 167 groundwater wells (Table 1), 12 monthly samples from Lake Davis (Table 2), 3 samples from Lake Davis tributaries (Table 2), and 8 Big Grizzly Creek samples (Table 2). Of the 167 groundwater wells sampled and analyzed, only 2 wells contained a significant component of evaporated water, with an isotope composition similar to Lake Davis water. The other 163 groundwater wells have isotope compositions which indicate that their water source is rain/snowmelt.« less

Joint Improvised-Threat Defeat Agency Needs to Improve Assessment and Documentation of Counter-Improvised Explosive Device Initiatives (Redacted)

DTIC Science & Technology

2016-08-09

2 Slight rounding inconsistencies exist because auditor calculations included decimals. (FOUO) Table 2. (FOUO) No. Initiative Title1 FY Action...rounding inconsistencies exist because auditor calculations included decimals. Acronyms: USAF United States Air Force USMC United States Marine Corps...exist because auditor calculations included decimals. (FOUO) Table 3. FOR OFFICIAL USE ONLY FOR OFFICIAL USE ONLY Management Comments 30 │ DODIG-2016

Water-resources activities of the U.S. Geological Survey in Kansas; fiscal years 1983 and 1984

USGS Publications Warehouse

Combs, L.J.

1985-01-01

The principal mission of the U.S. Geological Survey, Water Resources Division, in Kansas is to investigate the occurrence, quantity, quality, distribution, and movement of surface and ground waters throughout the State. Primary activities include the systematic collection, analysis, and interpretation of hydrologic data, evaluation of water demands, and water-resources research. Hydrologic investigations are conducted through four basic types of projects: (1) data-collection programs, (2) local or areal investigations, (3) statewide or regional investigations, and (4) research projects. These projects are funded through cooperative agreements with State and local agencies, transfer of funds from other Federal agencies, and direct Federal funds. Fifty water-related projects were ongoing during fiscal years 1983 and 1984 in Kansas. This report describes for each of these water-resources activities the problem that initiated the study, the objectives of the project, and the approach designed to achieve these objectives. Information on data-collection stations in Kansas is presented in maps and tables. A list of the 40 reports approved for publication by the U.S. Geological Survey, its cooperators, or technical and scientific organizations during 1983 and 1984 is provided. (USGS)

Optimization of water-level monitoring networks in the eastern Snake River Plain aquifer using a kriging-based genetic algorithm method

USGS Publications Warehouse

Fisher, Jason C.

2013-01-01

Long-term groundwater monitoring networks can provide essential information for the planning and management of water resources. Budget constraints in water resource management agencies often mean a reduction in the number of observation wells included in a monitoring network. A network design tool, distributed as an R package, was developed to determine which wells to exclude from a monitoring network because they add little or no beneficial information. A kriging-based genetic algorithm method was used to optimize the monitoring network. The algorithm was used to find the set of wells whose removal leads to the smallest increase in the weighted sum of the (1) mean standard error at all nodes in the kriging grid where the water table is estimated, (2) root-mean-squared-error between the measured and estimated water-level elevation at the removed sites, (3) mean standard deviation of measurements across time at the removed sites, and (4) mean measurement error of wells in the reduced network. The solution to the optimization problem (the best wells to retain in the monitoring network) depends on the total number of wells removed; this number is a management decision. The network design tool was applied to optimize two observation well networks monitoring the water table of the eastern Snake River Plain aquifer, Idaho; these networks include the 2008 Federal-State Cooperative water-level monitoring network (Co-op network) with 166 observation wells, and the 2008 U.S. Geological Survey-Idaho National Laboratory water-level monitoring network (USGS-INL network) with 171 wells. Each water-level monitoring network was optimized five times: by removing (1) 10, (2) 20, (3) 40, (4) 60, and (5) 80 observation wells from the original network. An examination of the trade-offs associated with changes in the number of wells to remove indicates that 20 wells can be removed from the Co-op network with a relatively small degradation of the estimated water table map, and 40 wells can be removed from the USGS-INL network before the water table map degradation accelerates. The optimal network designs indicate the robustness of the network design tool. Observation wells were removed from high well-density areas of the network while retaining the spatial pattern of the existing water-table map.

A quantitative analysis of hydraulic interaction processes in stream-aquifer systems

PubMed Central

Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; Li, Junting; Duan, Lei; Wang, Zhoufeng; Zhu, Lin

2016-01-01

The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. This study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources. PMID:26818442

Predictability and Quantification of Complex Groundwater Table Dynamics Driven by Irregular Surface Water Fluctuations

NASA Astrophysics Data System (ADS)

Xin, Pei; Wang, Shen S. J.; Shen, Chengji; Zhang, Zeyu; Lu, Chunhui; Li, Ling

2018-03-01

Shallow groundwater interacts strongly with surface water across a quarter of global land area, affecting significantly the terrestrial eco-hydrology and biogeochemistry. We examined groundwater behavior subjected to unimodal impulse and irregular surface water fluctuations, combining physical experiments, numerical simulations, and functional data analysis. Both the experiments and numerical simulations demonstrated a damped and delayed response of groundwater table to surface water fluctuations. To quantify this hysteretic shallow groundwater behavior, we developed a regression model with the Gamma distribution functions adopted to account for the dependence of groundwater behavior on antecedent surface water conditions. The regression model fits and predicts well the groundwater table oscillations resulting from propagation of irregular surface water fluctuations in both laboratory and large-scale aquifers. The coefficients of the Gamma distribution function vary spatially, reflecting the hysteresis effect associated with increased amplitude damping and delay as the fluctuation propagates. The regression model, in a relatively simple functional form, has demonstrated its capacity of reproducing high-order nonlinear effects that underpin the surface water and groundwater interactions. The finding has important implications for understanding and predicting shallow groundwater behavior and associated biogeochemical processes, and will contribute broadly to studies of groundwater-dependent ecology and biogeochemistry.

Rhode Island Water Supply System Management Plan Database (WSSMP-Version 1.0)

USGS Publications Warehouse

Granato, Gregory E.

2004-01-01

In Rhode Island, the availability of water of sufficient quality and quantity to meet current and future environmental and economic needs is vital to life and the State's economy. Water suppliers, the Rhode Island Water Resources Board (RIWRB), and other State agencies responsible for water resources in Rhode Island need information about available resources, the water-supply infrastructure, and water use patterns. These decision makers need historical, current, and future water-resource information. In 1997, the State of Rhode Island formalized a system of Water Supply System Management Plans (WSSMPs) to characterize and document relevant water-supply information. All major water suppliers (those that obtain, transport, purchase, or sell more than 50 million gallons of water per year) are required to prepare, maintain, and carry out WSSMPs. An electronic database for this WSSMP information has been deemed necessary by the RIWRB for water suppliers and State agencies to consistently document, maintain, and interpret the information in these plans. Availability of WSSMP data in standard formats will allow water suppliers and State agencies to improve the understanding of water-supply systems and to plan for future needs or water-supply emergencies. In 2002, however, the Rhode Island General Assembly passed a law that classifies some of the WSSMP information as confidential to protect the water-supply infrastructure from potential terrorist threats. Therefore the WSSMP database was designed for an implementation method that will balance security concerns with the information needs of the RIWRB, suppliers, other State agencies, and the public. A WSSMP database was developed by the U.S. Geological Survey in cooperation with the RIWRB. The database was designed to catalog WSSMP information in a format that would accommodate synthesis of current and future information about Rhode Island's water-supply infrastructure. This report documents the design and implementation of the WSSMP database. All WSSMP information in the database is, ultimately, linked to the individual water suppliers and to a WSSMP 'cycle' (which is currently a 5-year planning cycle for compiling WSSMP information). The database file contains 172 tables - 47 data tables, 61 association tables, 61 domain tables, and 3 example import-link tables. This database is currently implemented in the Microsoft Access database software because it is widely used within and outside of government and is familiar to many existing and potential customers. Design documentation facilitates current use and potential modification for future use of the database. Information within the structure of the WSSMP database file (WSSMPv01.mdb), a data dictionary file (WSSMPDD1.pdf), a detailed database-design diagram (WSSMPPL1.pdf), and this database-design report (OFR2004-1231.pdf) documents the design of the database. This report includes a discussion of each WSSMP data structure with an accompanying database-design diagram. Appendix 1 of this report is an index of the diagrams in the report and on the plate; this index is organized by table name in alphabetical order. Each of these products is included in digital format on the enclosed CD-ROM to facilitate use or modification of the database.

Toward Creation of a National Table for Aboriginal Literacy and Essential Skills (NTALES). Report on Meeting of May 27, 2014

ERIC Educational Resources Information Center

Canadian Literacy and Learning Network, 2014

2014-01-01

The Canadian Literacy and Learning Network (CLLN), in partnership with Aboriginal community leaders and literacy experts, is leading an initiative to create a National Table for Aboriginal Literacy and Essential Skills (NTALES). A potential role of the National Table will be to represent First Nation, Metis and Inuit literacy and essential skills…

Comparison of stratified and non-stratified most similar neighbour imputation for estimating stand tables

Treesearch

Bianca N. I. Eskelson; Hailemariam Temesgen; Tara M. Barrett

2008-01-01

Many growth and yield simulators require a stand table or tree-list to set the initial condition for projections in time. Most similar neighbour (MSN) approaches can be used for estimating stand tables from information commonly available on forest cover maps (e.g. height, volume, canopy cover, and species composition). Simulations were used to compare MSN (using an...

Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen

Treesearch

M.R. Chivers; M.R. Turetsky; J.M. Waddington; J.W. Harden; A.D. McGuire

2009-01-01

Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open...

Water table response to harvesting and simulated emerald ash borer mortality in black ash wetlands in Minnesota, USA

Treesearch

Robert A. Slesak; Christian F. Lenhart; Kenneth N. Brooks; Anthony W. D' Amato; Brian J. Palik

2014-01-01

Black ash wetlands are seriously threatened because of the invasive emerald ash borer (EAB). Wetland hydrology is likely to be modified following ash mortality, but the magnitude of hydrological impact following loss via EAB and alternative mitigation harvests is not clear. Our objective was to assess the water table response to simulated EAB and harvesting to...

40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

Code of Federal Regulations, 2012 CFR

2012-07-01

... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen

Treesearch

Evan S. Kane; Merritt R. Turetsky; Jennifer W. Harden; A. David McGuire; James M. Waddington

2010-01-01

Boreal wetland carbon cycling is vulnerable to climate change in part because hydrology and the extent of frozen ground have strong influences on plant and microbial functions. We examined the response of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) across an experimental manipulation of water table position (both raised and lowered water table...

Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

Treesearch

Kristine M. Haynes; Evan S. Kane; Lynette Potvin; Erik A. Lilleskov; Randy Kolka; Carl P. J. Mitchell

2017-01-01

Climate change is likely to significantly affect the hydrology, ecology, and ecosystem function of peatlands, with potentially important but unclear impacts on mercury mobility within and transport from peatlands. Using a full-factorial mesocosm approach, we investigated the potential impacts on mercury mobility of water table regime changes (high and low) and...

Organizing groundwater regimes and response thresholds by soils: A framework for understanding runoff generation in a headwater catchment

Treesearch

John P. Gannon; Scott W. Bailey; Kevin J. McGuire

2014-01-01

A network of shallow groundwater wells in a headwater catchment at the Hubbard Brook Experimental Forest in New Hampshire, U.S. was used to investigate the hydrologic behavior of five distinct soil morphological units. The soil morphological units were hypothesized to be indicative of distinct water table regimes. Water table fluctuations in the wells were...

40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

Code of Federal Regulations, 2010 CFR

2010-07-01

... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

Code of Federal Regulations, 2011 CFR

2011-07-01

... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

Paleohydrologic controls on soft-sediment deformation in the Navajo Sandstone

NASA Astrophysics Data System (ADS)

Bryant, Gerald; Cushman, Robert; Nick, Kevin; Miall, Andrew

2016-10-01

Many workers have noted the presence of contorted cross-strata in the Navajo Sandstone and other ancient eolianites, and have recognized their significance as indicators of sediment saturation during the accumulation history. Horowitz (1982) proposed a general model for the production of such features in ancient ergs by episodic, seismically induced liquefaction of accumulated sand. A key feature of that popular model is the prevalence of a flat water table, characteristic of a hyper-arid climatic regime, during deformation. Under arid climatic conditions, the water table is established by regional flow and liquefaction is limited to the saturated regions below the level of interdune troughs. However, various paleohydrological indicators from Navajo Sandstone outcrops point toward a broader range of water table configurations during the deformation history of that eolianite. Some outcrops reveal extensive deformation complexes that do not appear to have extended to the contemporary depositional surface. These km-scale zones of deformation, affecting multiple sets of cross-strata, and grading upward into undeformed crossbeds may represent deep water table conditions, coupled with high intensity triggers, which produced exclusively intrastratal deformation. Such occurrences contrast with smaller-scale complexes formed within the zone of interaction between the products of soft-sediment deformation and surface processes of deposition and erosion. The Horowitz model targets the smaller-scale deformation morphologies produced in this near-surface environment. This study examines the implications of a wet climatic regime for the Horowitz deformation model. It demonstrates how a contoured water table, characteristic of humid climates, may have facilitated deformation within active bedforms, as well as in the accumulation. Intra-dune deformation would enable deflation of deformation features during the normal course of dune migration, more parsimoniously accounting for: the frequent occurrence of erosionally truncated deformation structures in the Navajo Sandstone; the production of such erosional truncations during bedform climb and aggradation of the accumulation; and the dramatic fluctuations in the water table required to deposit dry eolian sand, deform those deposits under saturated conditions, and then dry the deformed sand to enable deflation.

Water and nitrogen management effects on water and nitrogen fluxes in Florida Flatwoods.

PubMed

Hendricks, Gregory S; Shukla, Sanjay

2011-01-01

The effects of water and fertilizer best management practices (BMPs) have not been quantified for groundwater nitrogen (N) beneath seepage irrigated vegetable fields with shallow water table environments. This effect was evaluated by a 3-yr study conducted in the Flatwoods of south Florida for watermelon ( cv. Mardi Gras and Tri-X 313) and tomato ( cv. BHN 586) using three treatments of water and inorganic fertilizer N (N) rates: (i) high fertilizer and water rates with seepage irrigation (HR), (ii) recommended fertilizer and water rates (BMP) with seepage irrigation (RR); and (iii) RR with subsurface drip irrigation (RR-SD). These treatments were implemented on six hydraulically isolated plots. The N rate treatments for high (HR) and recommended (RR and RR-SD) were based on a grower survey and BMP recommendations, respectively. Water applied, water table depth, and soil moisture content were regularly monitored for each treatment. Plant, soil, and groundwater N sampling and analyses were conducted for each season of the 3-yr study. The average water applied in HR (187 cm) was greater than RR (172 cm) and RR-SD (94 cm). Soil N maintained in crop beds for HR was significantly higher than RR and RR-SD. Soil solution analyses showed that N leached beneath HR (112 mg L) was greater ( = 0.053) than RR (76 mg L) and RR-SD (88 mg L). Shallow groundwater concentrations of dissolved inorganic nitrogen (NH-N + NO-N) were higher ( = 0.02) in HR (37 mg L) compared with RR (15 mg L) and RR-SD (19 mg L). Decreased N and water table levels can improve groundwater quality by reducing N leachate in shallow water table environments with seepage irrigated vegetable production systems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Woody riparian vegetation response to different alluvial water table regimes

USGS Publications Warehouse

Shafroth, P.B.; Stromberg, J.C.; Patten, D.T.

2000-01-01

Woody riparian vegetation in western North American riparian ecosystems is commonly dependent on alluvial groundwater. Various natural and anthropogenic mechanisms can cause groundwater declines that stress riparian vegetation, but little quantitative information exists on the nature of plant response to different magnitudes, rates, and durations of groundwater decline. We observed groundwater dynamics and the response of Populus fremontii, Salix gooddingii, and Tamarix ramosissima saplings at 3 sites between 1995 and 1997 along the Bill Williams River, Arizona. At a site where the lowest observed groundwater level in 1996 (-1.97 m) was 1.11 m lower than that in 1995 (-0.86 m), 92-100% of Populus and Salix saplings died, whereas 0-13% of Tamarix stems died. A site with greater absolute water table depths in 1996 (-2.55 m), but less change from the 1995 condition (0.55 m), showed less Populus and Salix mortality and increased basal area. Excavations of sapling roots suggest that root distribution is related to groundwater history. Therefore, a decline in water table relative to the condition under which roots developed may strand plant roots where they cannot obtain sufficient moisture. Plant response is likely mediated by other factors such as soil texture and stratigraphy, availability of precipitation-derived soil moisture, physiological and morphological adaptations to water stress, and tree age. An understanding of the relationships between water table declines and plant response may enable land and water managers to avoid activities that are likely to stress desirable riparian vegetation.

Descriptions and characterizations of water-level data and groundwater flow for the Brewster Boulevard and Castle Hayne Aquifer Systems and the Tarawa Terrace Aquifer

USGS Publications Warehouse

Faye, Robert E.; Jones, L. Elliott; Suárez-Soto, René J.

2013-01-01

This supplement of Chapter A (Supplement 3) summarizes results of analyses of groundwater-level data and describes corresponding elements of groundwater flow such as vertical hydraulic gradients useful for groundwater-flow model calibration. Field data as well as theoretical concepts indicate that potentiometric surfaces within the study area are shown to resemble to a large degree a subdued replica of surface topography. Consequently, precipitation that infiltrates to the water table flows laterally from highland to lowland areas and eventually discharges to streams such as Northeast and Wallace Creeks and New River. Vertically downward hydraulic gradients occur in highland areas resulting in the transfer of groundwater from shallow relatively unconfined aquifers to underlying confined or semi-confined aquifers. Conversely, in the vicinity of large streams such as Wallace and Frenchs Creeks, diffuse upward leakage occurs from underlying confined or semi-confined aquifers. Point water-level data indicating water-table altitudes, water-table altitudes estimated using a regression equation, and estimates of stream levels determined from a digital elevation model (DEM) and topographic maps were used to estimate a predevelopment water-table surface in the study area. Approximate flow lines along hydraulic gradients are shown on a predevelopment potentiometric surface map and extend from highland areas where potentiometric levels are greatest toward streams such as Wallace Creek and Northeast Creek. The distribution of potentiometric levels and corresponding groundwater-flow directions conform closely to related descriptions of the conceptual model.

Impact of Persistent Degassing of Kilauea Volcano on Domestic Water Supplies

NASA Astrophysics Data System (ADS)

Thomas, D. M.; Macomber, T.

2010-12-01

In March, 2008, a small explosive eruption in the summit crater of Kilauea Volcano marked the initiation of a new, persistently degassing vent at Kilauea. Emission rates of sulfur dioxide initially exceeded 1000 tons per day but declined to a longer term rate of ~800 tons per day. Because of its location farther inland, the plume from this vent generated more severe and more frequent adverse air quality impacts on the surrounding and downwind communities than has the longer lived degassing vents at Pu'u O'o. Because many residents on Hawaii Island derive their domestic water supply from roof catchment systems, deposition of aerosols produced in the volcanic plume could pose a significant health threat to the community. In order to quantify that risk, a program of screening of water catchment systems was undertaken in three communities: Lower Puna, upwind of the vent; Volcano Village, immediately adjacent to the Kilauea summit; and Hawaiian Ocean View Estates, located ~65 km downwind from the vent. An aggregate of 439 samples were collected and analyzed for pH, and fluoride, chloride and sulfate ion concentrations; the median values and extrema are shown in Table I below. The pH values for the catchments proved not to be a good indicator of plume influence: the Volcano and Ocean View communities showed a bimodal distribution of values reflecting residents managing their water systems (median pH = 6.2 and 7.2 respectively) and those that didn't (median pH = 4.5 and 4.3 respectively); however, the lower extremes for pH gave values of 2.9 and 3.3 respectively. Chloride values were also variable due to the use of sodium hypochlorite to treat for biological contaminants. The median values for fluoride and sulfate show a progressive increase from the Puna catchments to Volcano and Ocean View. We believe that these values are consistent with the relative exposure of the communities to the volcanic plume: although the Volcano community is closer to the source, wind conditions conducive to exposure are infrequent whereas the more distant Ocean View community is exposed to a more dilute plume but at a much higher frequency. Even though the median values are within accepted limits for drinking water, the extreme values observed are cause for concern: the pH values are well below those recommended for drinking water and the fluoride values are approaching WHO recommended drinking water levels. With even modest increases in plume output or exposure times, some of the community catchment systems can accumulate sufficient acid or fluoride ion concentrations to pose a significant health threat if drinking water is drawn from those catchments. Continued monitoring of catchment water quality is recommended.Table I. Catchment Water Supply Analytical Results Concentrations in parts per million

Modelling water table drawdown and recovery during tunnel excavation in fractured rock: estimating environmental impacts and characterizing uncertainties in a heterogeneous domain

NASA Astrophysics Data System (ADS)

Sege, J.; Li, Y.; Chang, C. F.; Chen, J.; Chen, Z.; Rubin, Y.; Li, X.; Hehua, Z.; Wang, C.; Osorio-Murillo, C. A.

2015-12-01

This study will develop a numerical model to characterize the perturbation of local groundwater systems by underground tunnel construction. Tunnels and other underground spaces act as conduits that remove water from the surrounding aquifer, and may lead to drawdown of the water table. Significant declines in water table elevation can cause environmental impacts by altering root zone soil moisture and changing inflows to surface waters. Currently, it is common to use analytical solutions to estimate groundwater fluxes through tunnel walls. However, these solutions often neglect spatial and temporal heterogeneity in aquifer parameters and system stresses. Some heterogeneous parameters, such as fracture densities, can significantly affect tunnel inflows. This study will focus on numerical approaches that incorporate heterogeneity across a range of scales. Time-dependent simulations will be undertaken to compute drawdown at various stages of excavation, and to model water table recovery after low-conductivity liners are applied to the tunnel walls. This approach will assist planners in anticipating environmental impacts to local surface waters and vegetation, and in computing the amount of tunnel inflow reduction required to meet environmental targets. The authors will also focus on managing uncertainty in model parameters. For greater planning applicability, extremes of a priori parameter ranges will be explored in order to anticipate best- and worst-case scenarios. For calibration and verification purposes, the model will be applied to a completed tunnel project in Mount Mingtang, China, where tunnel inflows were recorded throughout the construction process.

Exploring the ground ice recharge near permafrost table on the central Qinghai-Tibet Plateau using chemical and isotopic data

NASA Astrophysics Data System (ADS)

Wang, Weihua; Wu, Tonghua; Zhao, Lin; Li, Ren; Zhu, Xiaofan; Wang, Wanrui; Yang, Shuhua; Qin, Yanhui; Hao, Junmin

2018-05-01

Thawing permafrost on the Qinghai-Tibet Plateau (QTP) has great impacts on the local hydrological process by way of causing ground ice to thaw. Until now there is little knowledge on ground ice hydrology near permafrost table under a warming climate. This study applied stable tracers (isotopes and chloride) and hydrograph separation model to quantify the sources of ground ice near permafrost table in continuous permafrost regions of the central QTP. The results indicated that the ground ice near permafrost table was mainly supplied by active layer water and permafrost water, accounting for 58.9 to 87.0% and 13.0 to 41.1%, respectively, which implying that the active layer was the dominant source. The contribution rates from the active layer to the ground ice in alpine meadow (59 to 69%) was less than that in alpine steppe (70 to 87%). It showed well-developed hydrogeochemical depth gradients, presenting depleted isotopes and positive chemical gradients with depth within the soil layer. The effects of evaporation and freeze-out fractionation on the soil water and ground ice were evident. The results provide additional insights into ground ice sources and cycling near permafrost table in permafrost terrain, and would be helpful for improving process-based detailed hydrologic models under the occurring global warming.

Increasing the utility of regional water table maps: a new method for estimating groundwater recharge

NASA Astrophysics Data System (ADS)

Gilmore, T. E.; Zlotnik, V. A.; Johnson, M.

2017-12-01

Groundwater table elevations are one of the most fundamental measurements used to characterize unconfined aquifers, groundwater flow patterns, and aquifer sustainability over time. In this study, we developed an analytical model that relies on analysis of groundwater elevation contour (equipotential) shape, aquifer transmissivity, and streambed gradient between two parallel, perennial streams. Using two existing regional water table maps, created at different times using different methods, our analysis of groundwater elevation contours, transmissivity and streambed gradient produced groundwater recharge rates (42-218 mm yr-1) that were consistent with previous independent recharge estimates from different methods. The three regions we investigated overly the High Plains Aquifer in Nebraska and included some areas where groundwater is used for irrigation. The three regions ranged from 1,500 to 3,300 km2, with either Sand Hills surficial geology, or Sand Hills transitioning to loess. Based on our results, the approach may be used to increase the value of existing water table maps, and may be useful as a diagnostic tool to evaluate the quality of groundwater table maps, identify areas in need of detailed aquifer characterization and expansion of groundwater monitoring networks, and/or as a first approximation before investing in more complex approaches to groundwater recharge estimation.

Influence of Dynamic Hydraulic Conditions on Nitrogen Cycling in Column Experiments

NASA Astrophysics Data System (ADS)

Gassen, Niklas; von Netzer, Frederick; Ryabenko, Evgenia; Lüders, Tillmann; Stumpp, Christine

2015-04-01

In order to improve management strategies of agricultural nitrogen input, it is of major importance to further understand which factors influence turnover processes within the nitrogen cycle. Many studies have focused on the fate of nitrate in hydrological systems, but up to date only little is known about the influence of dynamic hydraulic conditions on the fate of nitrate at the soil-groundwater interface. We conducted column experiments with natural sediment and compared a system with a fluctuating water table to systems with different water content and static conditions under the constant input of ammonia into the system. We used hydrochemical methods in order to trace nitrogen species, 15N isotope methods to get information about dominating turnover processes and microbial community analysis in order to connect hydrochemical and microbial information. We found that added ammonia was removed more effectively under dynamic hydraulic conditions than under static conditions. Furthermore, denitrification is the dominant process under saturated, static conditions, while nitrification is more important under unsaturated, static conditions. We conclude that a fluctuating water table creates hot spots where both nitrification and denitrification processes can occur spatially close to each other and therefore remove nitrogen more effectively from the system. Furthermore, the fluctuating water table enhances the exchange of solutes and triggers hot moments of solute turnover. Therefore we conclude that a fluctuating water table can amplify hot spots and trigger hot moments of nitrogen cycling.

The Coming and Going of Ice

NASA Image and Video Library

2015-12-10

Like Earth's water table, Mars has an ice table. Sometimes, the ice table coincides with the ground's surface as it does here. The knobby, pitted terrain is caused when ice is deposited and then sublimates over and over again. This geologic process is called "accrescence" and "decrescence" and also occurs on Neptune's moon Triton and on Pluto, though in the outer Solar System the ice is not water ice. Other evidence for ice here includes the rope-like, curved flow feature that resembles glacial flow. Solis Planum -- a huge mound south of Valles Marineris -- is the location of this image. http://photojournal.jpl.nasa.gov/catalog/PIA20208