Steady-state computer model of the water-table aquifer in the Mullica River basin, the Pine Barrens, New Jersey

A two-dimensional steady-state model of the water-table aquifer of the Mullica River basin was made to evaluate the flow system and data required to simulate it. The Mullica River basin covers 570 sq mi and is drained by numerous shallow streams. The water-table aquifer consists of sand and gravel intermixed with clay and silt. The computer model is based on a finite-difference method with stream-seepage equations coupled to the groundwater equation. The model was applied to the approximately steady-state conditions of March 1979. Initial estimates of streambed hydraulic conductance and aquifer hydraulic conductivity were adjusted until model water level matched measured water level within 5 ft for 41 of 42 wells. Also, model streamflow was within 20 percent of measured streamflow at 12 of 15 sites. The 5,000-ft grid spacing should be adequate for a future predictive model. The natural flow system is adequately simulated by a two-dimensional model. (USGS)