New USGS groundwater model offers better understanding of Edwards Aquifer
Thanks to a new groundwater flow model developed by the U.S. Geological Survey in cooperation with San Antonio Water System, scientists now have a better understanding of how water flows throughout the San Antonio, Texas, segment of the Edwards aquifer.
July 23, 2015 -- Thanks to a new groundwater flow model developed by the U.S. Geological Survey (USGS) in cooperation with San Antonio Water System (SAWS), scientists now have a better understanding of how water flows throughout the San Antonio, Texas, segment of the Edwards aquifer.
The Edwards aquifer is one of the most prolific aquifers in the world and provides more than 50 percent of the drinking water consumed in the San Antonio and Austin areas. The aquifer supplies water to south-central Texas for residential, recreational, industrial, and agricultural uses. Several endangered and threatened species are also sustained by groundwater discharged at Comal, San Marcos and Barton Springs.
The focus of the new USGS model is to simulate the interaction between fresh water and saline (salt) water and where the two mix, called the brackish-water transition zone. Model results indicate that effects on fresh water during a severe drought, such as the drought-of-record during 1950-56, would be minor.
This model improves on a previous USGS model that did not include analysis of the transition or saline zones. While this new model is capable of making predictions of spring flow, salinity concentrations and water levels in nearby wells, the reliability of these predictions are also measured through use of a tool known as uncertainty analysis, which few groundwater modeling studies currently provide.
The model, coupled with uncertainty analysis, improves understanding of the potential effects of severe drought on the movement of water within and between the different water-quality zones. The full USGS report on the model is available here.
"While the model shows little potential for movement of brackish water into fresh water, the research suggests there is a need for an improved understanding of some parts of the Edwards aquifer flow system," said USGS scientist Linzy Brakefield. "Better knowledge of how the aquifer is recharged and the relationship between recharge, pumping and spring flow is needed."