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....

Sensitivity Analysis of a Ground-Water-Flow Model
A sensitivity analysis was performed on 18 hydrological factors affecting steady-state groundwater flow in the Upper Floridan aquifer near Albany, southwestern Georgia. Computations were...

2-D Groundwater Transport of Reactive Solutes with Competitive Adsorption
This paper presents a 2-D model, with applications, for the groundwater transport with competitive adsorption of a metal, a ligand and a complex. The model, called METLI, computes advection-dominated...

Optimization of a Municipal Ground Water Production System in North-Central Oklahoma
A management model is being developed to optimize the municipal groundwater production system which supplies drinking water for the City of Enid, Oklahoma. The system is comprised of one...

Conjunctive Use of Surface Water and Groundwater Management
A mathematical model is presented for conjunctive management of connected surface and groundwater systems. The groundwater module is based on the linear, two-dimensional, horizontal flow...

Groundwater Management in the Main Aquifer of High Aswaan Dam
The High Aswaan Dam reservoir replenishes a groundwater aquifer which extends on both sides of the dam lake with variable thickness. The groundwater of this aquifer is used to irrigate...

Overview and Objectives of the Macrodispersion Experiment
TVA is conducting large-scale field experiments to better define movement and dispersion of contaminants in groundwater. This will support groundwater protection by making possible more...

Second Natural-Gradient Tracer Experiment
The Tennessee Valley Authority (TVA) has begun a second large-scale groundwater field experiment at the Columbus Groundwater Research test site in Mississippi. This research is a continuation...

Measurement and Analysis of Hydraulic Conductivity Variability of a Heterogeneous Aquifer
The spatial variability of hydraulic conductivity of a shallow alluvial aquifer was investigated using borehole flowmeter measurements. The study was conducted at the site of a large-scale...

 

 

 

 

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