Alternatives to Reduce Pumping Effects in Glacial Stratified Drift Aquifers During Periods of Low Stream Flow

摘要

Low stream flows in the Fenton River, part of a hydrogeological setting characterized by glacial stratified drift, forces the University of Connecticut to frequently reduce groundwater withdrawals during the months of June-October. The objective of this study was to investigate stream/aquifer interactions in such a hydrogeologic system in order to increase water withdrawals while minimizing adverse impacts to in-stream flow. A ground-water flow model was developed using MODFLOW to investigate the influence of well location and pumping timing on in-stream flow in the vicinity of the water supply wells. The numerical model comprised detailed geophysical data and decadal hydrologic data (2000-2009) to assess well placement, rest periods and cyclical pumping. The relocation of a water supply well up to 228 m from the river had a positive but minimal improvement to stream flows (＜2.83 L/s). When the well field was shut off for more than 45 days, stream flows returned to the no pumping condition with only slight impact at 30 days, whereas a 30 day rest period gave 4 weeks of dampened pumping influence on stream flows. A management scenario of 1 week cyclical pumping between two water supply wells following a 45 day rest period can allow for current restriction thresholds to be reduced by 28.3 L/s with minimal impact to stream flows (7.36 L/s) and would allow additional water to be pumped for all years in which there was a demand for water.