Hydrology of the Mississippi River valley alluvial aquifer, south-central United States

Ground-water flow simulation indicates that pumpage from the aquifer since the early 1900's has caused a decrease in ground-water outflow to rivers, an increase in flow from rivers into the aquifer, and an increase in flow to the aquifer through the overlying confining unit. By the mid-1970's, rivers became a source of more than 30 percent of total flow into the aquifer rather than the sink of net outflow, and by 1982 inflow through the overlying confining unit increased about 60 percent. Areas with the greatest potential for additional pumpage are northwestern Mississippi and northern parts of the area east of Crowleys Ridge.