scholarly journals Characterization and occurrence of confined and unconfined aquifers in Quaternary sediments in the glaciated conterminous United States

2019 ◽  
Author(s):  
Richard M. Yager ◽  
Leon J. Kauffman ◽  
David R. Soller ◽  
Adel E. Haj ◽  
Paul M. Heisig ◽  
...  
Keyword(s):  
United States ◽  
Quaternary Sediments ◽  
Unconfined Aquifers ◽  
Confined And Unconfined Aquifers

Nitrate in aquifers beneath agricultural systems

2002 ◽  
Vol 45 (9) ◽  
pp. 19-29 ◽  
Author(s):  
M.R. Burkart ◽  
J.D. Stoner
Keyword(s):  
United States ◽  
Groundwater Vulnerability ◽  
The United States ◽  
Point Sources ◽  
Nitrate Contamination ◽  
Agricultural System ◽  
Agricultural Systems ◽  
Fertilizer Use ◽  
Unconfined Aquifers ◽  
The World

Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey’s NAWQA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable and shallow carbonate aquifers provide a substantial but smaller contamination risk. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger. Irrigated systems can compound this vulnerability by increasing leaching facilitated by additional recharge and additional nutrient applications. The agricultural system of corn, soybeans, and hogs produced significantly larger concentrations of groundwater nitrate than all other agricultural systems, although mean nitrate concentrations in counties with dairy, poultry, cattle and grains, and horticulture systems were similar. If trends in the relation between increased fertilizer use and groundwater nitrate in the United States are repeated in other regions of the world, Asia may experience increasing problems because of recent increases in fertilizer use. Groundwater monitoring in Western and Eastern Europe as well as Russia over the next decade may provide data to determine if the trend in increased nitrate contamination can be reversed. If the concentrated livestock trend in the United States is global, it may be accompanied by increasing nitrogen contamination in groundwater. Concentrated livestock provide both point sources in the confinement area and intense non-point sources as fields close to facilities are used for manure disposal. Regions where irrigated cropland is expanding, such as in Asia, may experience the greatest impact of this practice.

scholarly journals On the Use of Electrical Resistivity Method in Mapping Potential Sources and Extent of Pollution of Groundwater Systems in Lapai Town, Niger State, Nigeria.

2021 ◽  
Vol 5 (1) ◽  
pp. 18
Author(s):  
Matthew Tersoo Tsepav ◽  
Aliyu Yahaya Badeggi ◽  
Obaje Nuhu George ◽  
Usman Yusuf Tanko ◽  
Ibrahim Samuel Ibbi
Keyword(s):  
Electrical Resistivity ◽  
Lateritic Soil ◽  
Protective Capacity ◽  
Unconfined Aquifers ◽  
Resistivity Method ◽  
Electrical Sounding ◽  
Groundwater Systems ◽  
Electrical Resistivity Method ◽  
Resistivity Meter ◽  
Confined And Unconfined Aquifers

<p>Electrical resistivity method employing the Schlumberger array was used to occupy forty four (44) vertical electrical sounding points in Lapai town with the aim of determining the depth to aquifers, aquifer thicknesses and aquifer protective capacity. The G41 Geotron resistivity meter was used in obtaining the apparent resistivity data which was processed using Interpex 1XD resistivity interpretation software. The results revealed four lithologic sections which include top lateritic soil, sandy clay, fractured basement and fresh basement. Both confined and unconfined aquifers were identified within the area, with four classes of aquifer proactive capacities as high, moderate, weak and poor. While the aquifer at VES 20 was highly protected, twenty other aquifers were moderately protected, eight others had weak protection and fifteen aquifers were poorly protected. The aquifers were generally of good thicknesses and at varying reasonable depths, making them good reservoirs of water in appreciable quantity. The average aquifer thickness was estimated to be 48.36m while the average depth to aquifers was estimated to be 56.68m.</p>

scholarly journals Analytical and Numerical Groundwater Flow Solutions for the FEMME-Modeling Environment

Hydrology ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 27 ◽  
Author(s):  
Mustafa El-Rawy ◽  
Okke Batelaan ◽  
Kerst Buis ◽  
Christian Anibas ◽  
Getachew Mohammed ◽  
...  
Keyword(s):  
Water Level ◽  
Numerical Solutions ◽  
Groundwater Model ◽  
One Dimensional ◽  
Water Interaction ◽  
Unconfined Aquifers ◽  
Different Types ◽  
Groundwater Surface Water Interaction ◽  
Confined And Unconfined Aquifers ◽  
Good Agreement

Simple analytical and numerical solutions for confined and unconfined groundwater-surface water interaction in one and two dimensions were developed in the STRIVE package (stream river ecosystem) as part of FEMME (flexible environment for mathematically modelling the environment). Analytical and numerical solutions for interaction between one-dimensional confined and unconfined aquifers and rivers were used to study the effects of a 0.5 m sudden rise in the river water level for 24 h. Furthermore, a two-dimensional groundwater model for an unconfined aquifer was developed and coupled with a one-dimensional hydrodynamic model. This model was applied on a 1 km long reach of the Aa River, Belgium. Two different types of river water level conditions were tested. A MODFLOW model was set up for these different types of water level condition in order to compare the results with the models implemented in STRIVE. The results of the analytical solutions for confined and unconfined aquifers were in good agreement with the numerical results. The results of the two-dimensional groundwater model developed in STRIVE also showed that there is a good agreement with the MODFLOW solutions. It is concluded that the facilities of STRIVE can be used to improve the understanding of groundwater-surface water interaction and to couple the groundwater module with other modules developed for STRIVE. With these new models STRIVE proves to be a powerful example as a development and testing environment for integrated water modeling.

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