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Streamflow Depletion
Intermediate to Advanced - Multi-layer aquifer modeling. Background: In almost all streams, there is movement of water between the underlying groundwater and the surface water body. Because of this interaction, depletions to streams due to pumping can occur either by wells that intercept water that otherwise would have flowed to the surface water bodies or by causing water to move from the streams to the well. Pumping-induced reductions in base flow are not instantaneous nor do they occur only to streams closest to the well. There can be significant interaction among surface water bodies and it can take years or decades for depletions to be fully realized.
(Stream Depletion - 8)
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Transient stream depletion
Use MAGNET to perform an evaluation of the following situation:
A well located 5000 ft from a stream which is connected to the aquifer discharges 500 gpm. The transmissivity of the aquifer is 105 ft2t/day, and the specific yield is 0.25. If pumping from the well is to be regulated so that the rate of withdrawal from the stream is less than 50% of the well discharge, how long may the well be pumped?
(Stream Depletion - 8)
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Water Withdrawal Assessment
When pumping near a stream, we are interested not only in the resulting drawdowns, but also in the depletion of the stream flow, resulting in potentially adverse impact of groundwater dependent ecosystems. Develop a more general MAGNET numerical model that can reproduce the above analytical solution and perform a sensitivity analysis of stream depletion with respect to the following parameters: aquifer conductivity; storage coefficient; regional hydraulic gradient; stream bed leakance; heterogeneity; presence of other interacting sources and sinks.
(Stream Depletion - 8)
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Water supply expansion and wetlands
Intermediate - 2D flow modeling and water balance analysis. Background: The town of Hubertville is planning to expand its water supply by constructing a pumping well in an unconfined aquifer. The well is designed to pump constantly at a rate of 20,000 m3/day. Well construction was halted by the State Fish and Game Service who manage the Green Swamp Conservation area. The agency claimed that pumping would “significantly reduce” groundwater discharge to the swamp and damage a waterfowl habitat. The town claimed the fully penetrating river boundary to the north and the groundwater divide located near the center of the valley would prevent any change in flow to the swamp.
(Stream Depletion - 8)
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Bank Filtration and Well Field Design for a Large-scale Water Supply
The possibility of developing a well field taking advantage of bank filtration for large scale water supply is being studied for the unconfined aquifer. The aquifer is developed in the alluvial sand deposits of perennial river. Using the provided information and MAGNET, develop a preliminary groundwater model for assessing the aquifer’s potential and designing the pumping network.
(Stream Depletion - 8)
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