Hydrogeology and stream interactions of the Edwards Aquifer in the Salado Creek Basin, Bell and Williamson Counties, Central Texas.

The northern extent of the Balcones Fault Zone Edwards aquifer discharges through more than 20 perennial springs into the lower reaches of the Salado Creek. In the upper reaches, Salado Creek is a losing stream and groundwater recharge occurs through the stream channel. The Balcones Fault Zone dissects, and displaces the Edwards aquifer within the Salado Creek basin. Fractures associated with faulting as well as weathering, diagenesis and neo-tectonic stresses contribute directly to the porosity and permeability of the aquifer. Groundwater flow is dominated by vertical fractures and bedding pane separations, augmented by dissolutioning, resulting in both diffuse and conduit flow. Lineations, observed on remote imagery, exhibit orientations related to regional structural trends. However, away from faulting, orientations become increasingly random. Lineation density increases near major faults zones, while the density away from faulting decreases. Field measurements of fractures, in differing lithologies, indicate localized heterogeneity and anisotropy. Fracture porosity that is not enhanced by cavernous development ranges from 0.41 percent to 4.25 percent. However, where localized cavernous porosity exists, the effective porosity may approach 10 percent (Baker and others, 1986, p. 50-56). The fracture-dominated flow system exhibits rapid water level responses to precipitation events, with groundwater rises corresponding to increases in stream flow. The groundwater flow systems are locally heterogeneous and anisotropic. However, the dominant regional control on the groundwater flow direction is the structural dip and topography, both of which slope eastward. An exception is the area near major Balcones Faults, south of the town of Salado. At this location appreciable regional anisotropy exists due to increased fracture occurrence, which dictates a northern groundwater flow direction. A water budget for the aquifer within the Salado Creek basin shows 88.34 percent of the annual rainfall is evaporated or transpired. The total yearly groundwater discharge (11.15%) and estimated yearly recharge (12.75%) is close. About 9.8 percent of the recharge is point source through the losing stream segment and about 90.2 percent of the recharge is areal.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Masters

Grantor

Baylor University.

Year dc:date.issued

1990

Author dc:creator

• Dahl, Suzanne Lisa.

Advisor dc:contributor.advisor

• Yelderman, Joe C.

• Hydrogeology.
• Groundwater flow -- Texas -- Salado Creek Basin.
• Edwards Aquifer (Tex.)
• Salado Creek Basin (Tex.)
• Bell County (Tex.)
• Williamson County (Tex.)

Statement dc:rights

• Baylor University works are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact libraryquestions@baylor.edu for inquiries about permission.

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2104/13620

OAI identifier oai:identifier

oai:baylor-ir.tdl.org:2104/13620