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SwRI study to focus on Edwards Aquifer's "Knippa Gap" in Uvalde County

San Antonio -- November 2, 2004 -- Southwest Research Institute® (SwRI®) scientists will study the geology and hydrology of the western portion of the Edwards aquifer, an area that contains some unusual geologic formations, under contract with the Edwards Aquifer Authority.

The 16-month study is intended to determine whether subsurface structures known as the "Knippa Gap" in Uvalde County, 75 miles west of San Antonio, may alter or restrict the gradual, eastward-trending movement of Edwards water through the giant limestone reservoir that stretches from the area of Brackettville in Kinney County to the area of Kyle in Hays County. In particular, the study will attempt to provide characterization of the hydraulic relationship between the "Uvalde" pool and the "San Antonio" pool portions of the Edwards aquifer.

"To accomplish this objective, the study will refine the characterization of the groundwater environment in Uvalde and surrounding areas," said Staff Scientist Dr. Ronald Green, a hydrogeologist with the CNWRA Division at SwRI, which is conducting the study.

"The Knippa Gap is not well understood," he said. "Hydrogeologically it's a complex area, but effective management of the Edwards aquifer depends on this kind of information."

Scientists and geologists from the Institute will survey existing wells in Uvalde, Kinney and western Medina counties and analyze the chemistry of water from those wells as a means to identify the origins and movement of water through the aquifer.

They also will perform a geologic structural analysis that will include mapping faults and geologic units such as igneous bodies and sedimentary strata, determining the depth and thickness of the aquifer and producing a model of the groundwater system beneath the Uvalde area. They will team with Raba-Kistner Consultants Inc. and Robert Maclay.

For more information about the project contact Green at (210) 522-5305 or

For more information contact Joe Fohn, Communications Department, at (210) 522-4630, PO Drawer 28510, San Antonio, TX 78228-0510.

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