USGS Pennsylvania Water Science Center
In cooperation with the U.S. Environmental Protection Agency
Presentation at the 2014 Pennsylvania Groundwater Symposium, May 7, 2014, State College, Pennsylvania.
Streamflow Depletion by Groundwater Pumping from Fractured-Rock Aquifers of the Newark Basin
by Daniel J. Goode,
Lisa A. Senior, and Dennis W. Risser
Seepage measurements and simulation of groundwater pumping from Brunswick Group and Lockatong Formation aquifers in and around Lansdale, Montgomery County, southeastern Pennsylvania, showed depletion of base flow in headwater streams. Groundwater base flow to streams occurs through a shallow weathered zone, which generally has lower permeability than the unweathered fractured rock. Simulations verified that long-term, large-scale water-supply pumping of groundwater has substantially depleted base flow in headwater streams, despite the slow response of shallow water levels to pumping from deeper strata and the resultant lag in changes to base flow. The simulated 1994 water budget indicated that 51 percent of groundwater recharge was removed by pumping and only 49 percent discharged as base flow. By 2010 base flow had recovered somewhat because water supplies shifted to surface-water sources and groundwater withdrawals decreased by 42 percent. Several waste-water-treatment plants discharge to local streams, resulting in increases in down-stream flow, but these plant discharges represent an interbasin transfer of groundwater because some of the water transported to these plants originated in an adjacent groundwater basin. Simulated groundwater basins, defined as land-surface areas through which distributed recharge becomes base flow to the stream network, are not fully coincident with the surface-water drainage basins.
Goode, D.J., Senior, LA., and Risser, D.W., 2014, Streamflow depletion by groundwater pumping from fractured-rock aquifers of the Newark Basin (abs.): 2014 Pennsylvania Ground Symposium, May 7, 2014, State College, Pennsylvania. [https://pa.water.usgs.gov/projects/groundwater/frhr/goode2014b.php]