Simulated effects of alternative withdrawal strategies on ground-water-flow patterns, New Jersey Pinelands

A steady-state, three-dimensional ground-water- flow model of the unconfined part of the Kirkwood- Cohasey aquifer system beneath the upper parts of the Rancocas Creek and Wading River Basins in the New Jersey Pinelands was developed to (1) define ground-water-flow patterns and residence times in an aquifer system typical of the New Jersey Coastal Plain and (2) demonstrate the effects of alternative withdrawal strategies of ground- water-flow patterns and streams. Ground-water flow near the McDonald's-Middle Branch area was analyzed by using a particle tracker to demonstrate the effects of three hypothetical withdrawal scenarios on the configurations of source areas of ground-water flow to withdrawal wells, streams, and other discharge outlets in the Kirkwood-Cohansey aquifer system. Under natural conditions, most ground-water discharge to streams and wetlands. Ground-water residence times ranged from slightly greater than zero to about 200 years. Much of the ground water remained in the system for less than 20 years because it discharged to streams. Residence times of ground water were reduced significantly by persistent withdrawals. The configurations of source areas of flow to local stream systems and to the Piney Point aquifer are affected by the location of a withdrawal well. Results of withdrawal simulations indicate that well-location strategies applied in the Kirkwood-Cohansey aquifer system can alleviate the adverse effects of withdrawals on streams and that large-scale regional withdrawals in confined aquifers can adversely effect streams although the effects are dispersed over numerous streams.