Man’s impact on the ground-water resources within the Mississippi Embayment Regional Aquifer Study (MERAS) area is a primary component in the preparation of the MERAS ground-water flow model. The MERAS model area encompasses approximately 70,000 square miles in parts of Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee.

Water-use data were compiled for 130,000 ground-water withdrawal points representing over 130 years of withdrawals. Water-use data for the following categories were collected: irrigation, agriculture, industry, commercial, mining, power generation, and public supply. Site-specific data were used for some of the published water-use reports from 1980-2000. Summation of yearly and 5 year withdrawal amounts and number of withdrawal points by aquifer from 1980 to 2005 were tabulated to calculate an average withdrawal amount per withdrawal point (by aquifer). A exponential trend line was used to estimate withdrawals by aquifer for each model stress period where there was no available data. The average withdrawal amount per withdrawal point was used to calculate the number of points required to produce the estimated withdrawal amount for each stress period. The points were then distributed randomly to existing locations selected from the Ground Water Site Inventory database for each stress period. Monthly water-use data were used to determine seasonal water-use variation. This process was repeated for each aquifer being modeled. The procedures and process used to estimate water use will be invaluable for future withdrawal input for ground-water modeling.