Dec 02, 2011

USGS Says Groundwater Storage Losses Substantial Across Aquifer System

Mississippi embayment aquifer system covers areas in eight states

More than 280 million acre-ft of groundwater has been withdrawn from the Mississippi embayment aquifer system between 1870 and 2007, according to a new water modeling tool developed by the U.S. Geological Survey (USGS). The cumulative withdrawal, which is the equivalent of 5 ft of water over 78,000 sq miles, contributes to one of the largest losses of groundwater storage anywhere in the United States.

The new USGS modeling tool was designed to help resource managers find a balance between water supply and demand for future economic and environmental uses. The 3-D model provides a holistic picture of how water flows below ground and how it relates to surface water. The Mississippi embayment aquifer system encompasses approximately 78,000 sq miles in Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri and Tennessee. A report documenting past and current groundwater conditions, and tools to forecast regional response to human use, climate variability and land-use changes are available online.

"This model can assist water resource managers faced with increasing management challenges and constraints," said USGS hydrologist Brian Clark. "This model could be used to evaluate regional issues, such as streamflow declines from groundwater pumping, or conservation scenarios to lessen water level declines."

The Mississippi embayment aquifer system includes one of the nation’s most productive agricultural regions, with an annual value of $3 billion per year. Two of the region’s most important aquifers lie beneath the Mississippi embayment. The pumping from the Mississippi River Valley alluvial aquifer accounts for more than 12% of all groundwater pumped in the United States.

The report is a product of a four-year study being funded by the USGS Groundwater Resources Program. Information derived from it and future studies of more than 30 regional aquifers will provide a collective assessment of America's groundwater availability.

To develop the model, scientists examined more than 2,600 geophysical logs, some dating back to the early 1960s. Researchers examined groundwater and surface water data from the early 1900s to 2007, groundwater withdrawal information, and thousands of miles of surface water bodies to illustrate how the water system works and how supplies have changed.