Estimating Upland Recharge in the Yucca Mountain Area
Field and modeling studies were conducted recently for the Fortymile Canyon watershed and the Rock Valley area near the site of the proposed high-level nuclear waste repository at Yucca...
Source of Atrazine and Desethylatrazine in a River, During Base Flow
A budget of atrazine and desethylatrazine loads was computed for a 116-kilometer reach of the Cedar River in Iowa to determine where these compounds enter the river during base-flow conditions....
Water Quality of Shallow Groundwater Reused for Irrigation
Drainage water was collected by subsurface drains and reapplied to half of a drained alfalfa field in Fallon, Nevada, during the 1989 irrigation season. Irrigation district water was applied...
Hydrologic and Geochemical Approaches for Determining Ground-Water Flow Components
Lyman Lake is an irrigation-storage reservoir on the Little Colorado River near St. Johns, Arizona. The main sources of water for the lake are streamflow in the Little Colorado River and...
A Coupled Surface-Water and Ground-Water Model
In areas with dynamic and hydraulically well connected ground-water and surface-water systems, it is desirable that stream-aquifer interaction be simulated with models of equal sophistication...
Ground Water Modeling Using the Method of Lines (MOL)
The development of robust general purpose numerical algorithms for initial-boundary value ordinary differential equations (ODEs) which use the method of lines (MOL) makes the solution...
Surface Water/Groundwater Interaction Studies
Studies were performed on a high elevation (2440 meters or 8000 feet) valley stream system and a high (1980 meters or 6500 feet) cold desert stream system in Wyoming, to analyze the surface...
Underground Water Conservation Districts: A Case Study in Water Resources Management
Ground water supplies approximately half of the annual water use in the state of Texas. The water law system in the state is extremely complex and non-integrated, making the management...
Use of Stable Isotopes, Tritium, Soluble Salts, and Redox-Sensitive Elements to Distinguish Ground Water from Irrigation Water in the Salton Sea Basin
Evaporative concentration of irrigation water diverted from the Colorado River to the Salton Sea basin for several decades has produced an overlying system (that includes drainwater and...
Uncertainty in Pesticide Leaching Potential
Uncertainty in the pesticide leaching index AF is examined for the pesticides Atrazine and Diuron with attention to the contribution of temporal variability and estimation error in recharge....
Economic Evaluation of Farning Systems to Protect Surface and Ground Water Quality
Two approaches are discussed for evaluating the economic and environmental effects of farming systems designed to protect water quality. The scenario approach evaluates specific farming...
Ground Water Impacts from Irrigated Ridge-Tillage
The Northern Cornbelt Sand Plain Project is a cooperative research effort between the State Agricultural Experiment Stations, USDA/Agricultural Research Service and U.S. Geological Survey...
Impact of Nitrogen and Water Management on Ground Water Quality
Nitrate-nitrogen (NO3-N) concentrations in shallow ground water of the Platte River Valley in Central Nebraska have been increasing since the 1950s...
Impact of Farming Systems on Water Quality in Iowa
Increased detection of nitrate and pesticides in surface and ground water has prompted concern about the impact of farming systems on water quality. A number of studies have been incorporated...
Long-Term Effects of Tillage and Crop Rotation on the Leaching of Nitrate and Pesticides to Shallow Groundwater
Contamination of groundwater by nitrate-nitrogen (NO3-N) and pesticides is a serious problem and concern in Iowa. The extent of contamination can...
The National Water-Quality Assessment (NAWQA) Program?A Basis for Water-Resource Policy Development
The concepts that are the basis for the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program began forming in the early 1980's. By 1986,...
Effects of Wastewater Irrigation on Aqueous Geochemistry
A comprehensive assessment of the environmental impact of a full-scale, operating overland flow (OLF) land treatment system was made of the Campbell Soup, Inc. OLF system in Paris, Texas....
Common Mistakes in Model Applications
To apply models to groundwater problems, the hydrologist generally uses the following three-phased approach: (1) system conceptualization, (2) history matching (or model calibration),...
Impact of Grid Orientation on Groundwater Contaminant Transport Modeling Using the U.S.G.S. MOC Model
The U.S.G.S. method of characteristics (MOC) model was enhanced to include the input of measured contaminant concentrations, the calculation of computed and measured contaminant plume...
Evaluating Probability Measures Related to Subsurface Flow and Transport: Overview of Technical Considerations and Modeling Philosophy
Probabilistic modeling approaches are being used increasingly in order to carry out quantified risk analysis and to evaluate the uncertainty existing in subsurface flow and transport analyses....
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