Numerical Simulation of Groundwater Flow Within the Atlantic Coastal Plain Aquifers of North and South Carolina

The Atlantic Coastal Plain aquifer system of North and South Carolina is an important source of potable water for a growing population. The 2000 Census reported that the combined populations of Coastal Plain counties in North Carolina and South Carolina totaled nearly 6 million people with 3.2 million located in North Carolina and 2.5 million in South Carolina. In North Carolina, the population grew by 21-percent from 1990-2000. The population is projected to grow another 13-percent by the year 2015. The numbers are similar in South Carolina with a population increase of 15-percent from 1990-2000 and a projected 13-percent increase by 2015. The Atlantic Coastal Plain aquifer system has a large aerial extent, covering approximately 25,000 square miles in North Carolina and approximately 20,000 square miles in South Carolina. Most of the Coastal Plain is underlain by at least one and in some areas, several highly productive aquifers. Although groundwater resources have been intensively developed in some areas of the Atlantic Coastal Plain, large areas remain relatively undeveloped. The complicated history of water use, along with substantial areal variations in aquifer properties pose challenges for the State agencies charged with managing these important resources. As more users demand more water, the need for scientifically based management tools has increased. A numerical groundwater-flow model is such a tool that can be used to integrate and evaluate large volumes of groundwater data to assist in the management of these important groundwater resources. To help State agencies address issues concerning the management and development of the Atlantic Coastal Plain aquifers in North and South Carolina, steady-state and transient groundwater flow models are being developed by the U.S. Geological Survey (USGS) using the USGS finite-difference groundwater flow model, MODFLOW-2000.