Hydrogeologic aspects of the Knippa Gap area in eastern Uvalde and western Medina counties, Texas

Fact Sheet 2014-3045
Prepared in cooperation with the U.S. Army Corps of Engineers
By: , and 

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Abstract

The Edwards aquifer is the primary source of potable water for the San Antonio area in south-central Texas. The Knippa Gap area is a structural low (trough) postulated to channel or restrict flow in the Edwards aquifer in eastern Uvalde and western Medina Counties, Tex. To better understand the function of the Knippa Gap, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, developed the first detailed surficial geologic map of the Knippa Gap area with data and information obtained from previous investigations and field observations. A simplified version of the detailed geologic map depicting the hydrologic units, faulting, and structural dips of the Knippa Gap area is provided in this fact sheet. The map shows that groundwater flow in the Edwards aquifer is influenced by the Balcones Fault Zone, a structurally complex area of the aquifer that contains relay ramps that have formed in extensional fault systems and allowed for deformational changes along fault blocks. Faulting in southeast Uvalde and southwest Medina Counties has produced relay-ramp structures that dip downgradient to the structural low (trough) of the Knippa Gap.

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Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Hydrogeologic aspects of the Knippa Gap area in eastern Uvalde and western Medina counties, Texas
Series title Fact Sheet
Series number 2014-3045
DOI 10.3133/fs20143045
Year Published 2014
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Texas Water Science Center
Description 6 p.
Country United States
State Texas
County Medina County, Uvalde County
Other Geospatial Knippa Gap
Datum North American Datum of 1983
Projection Universal Transverse Mercator projection
Scale 250000
Online Only (Y/N) N
Additional Online Files (Y/N) N