Objectives: Determine the impact of a now flow boundary on
groundwater pumping in a confined aquifer.
1. Groundwater drawdowns in wells can be impacted in
aquifers that are adjacent to no flow boundaries, such as impermeable faults or
even building foundations. These no flow
boundaries cause an asymmetry in the cone of depression. In order to solve this style of problem, we
can use image wells, which are imaginary wells that are added to the system to
represent drawdown at the no flow boundary.
The foldable aquifer model that is provided in the problem below asks
you to solve one of these drawdown problems, where the pumping well is adjacent a no
flow boundary. Before pumping there is no
gradient across the confined aquifer as shown by the dashed line. Use the foldable aquifer model provided to
answer the following question
A. Determine the pumping rate at the well needed to cause
the confined limestone aquifer to become unconfined adjacent to the fault.
B. Once the confined limestone aquifer becomes unconfined adjacent
to the fault what is the direction of groundwater flow. If you were to then turn the pumping well off
how would this direction of groundwater flow change.
C. If the fault was replaced by a lake of infinite volume
what would the pumping rate would be needed to cause the limestone aquifer to
become unconfined.
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