Recalibration of a ground-water flow model of the Mississippi River Valley alluvial aquifer in southeastern Arkansas, 1918-1998, with simulations of hydraulic heads caused by projected ground-water withdrawals through 2049

To evaluate the effects of projected ground water withdrawals, three scenarios were used to simulate a range of possible withdrawals. Five additional stress periods of 10 years each were added to the model to facilitate predictive scenario generation. The predictive scenarios control pumpage by either continuing 1997 pumpage into the future (scenario 1) or by increasing water-use trends into the future (scenario 2 and 3). The ASWCC Critical Ground Water area designation includes a requirement that a 50-percent saturated formation thickness be maintained. For this reason, the level of 50-percent saturated formation thickness is used as a reference surface in the scenario output presented. Animations of simulated heads changing through time are included on the compact disc in the "Animations" folder. In the animations, the level of 50 percent saturated formation thickness is indicated by a mesh surface and the dry cells appear as voids in the model surface.