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Research about San Antonio, Texas

Source-linked reports with geographic coverage including San Antonio, Texas.

29 records · Page 2Linked to original sources
USGS1987

Simulation of flow in the Edwards Aquifer, San Antonio region, Texas, and refinement of storage and flow concepts

The Edwards aquifer is a complexly faulted, carbonate aquifer lying within the Balcones fault zone of south-central Texas. The aquifer is recharged mainly by streamflow losses in the outcrop area of the Edwards aquifer and is discharged by major springs located at considerable distances, as much as 150 mi, from the areas of recharge, and by wells. Groundwater flow within the Edwards aquifer of the San Antonio region was simulated to investigate concepts relating to the storage and flow characteristics. A general purpose, finite difference model, modified to provide the capability of representing barrier faults, was used to simulate groundwater flow and storage in the aquifer. The simulations investigated the effects of complex geologic structures and significant changes in transmissivity, anisotropy, and storage coefficient, with initial values based on concepts developed in previous studies. Results of the simulations confirmed the original estimates of transmissivity values (> 100 sq ft/sec) in the confined zone of the aquifer between San Antonio and Comal Springs. A storage coefficient of 0.05 in the unconfined zone of the aquifer produced the best simulation of water levels and springflow. A major interpretation resulting from the simulations is that two essentially independent areas of regional flow were identified in the west and central part of the study area. Flow from the two areas converges at Comal Springs. The directions of computed flux vectors reflected the presence of major barrier faults which locally deflect patterns of groundwater movement. The most noticeable deflection is the convergence of flow through the geologic structural opening, the Knippa gap, in eastern Uvalde County. A second significant interpretation is that groundwater flow in northeastern Bexar, Comal, and Hays Counties is diverted by barrier faults toward San Marcos Springs, a regional discharge point. (Lantz-PTT)

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USGS1986

Hydrogeologic sections of the Edwards Aquifer and its confining units in the San Antonio area, Texas

Twenty-seven geohydrology sections illustrate structural and stratigraphic relationships within the 180-mi-long Edwards aquifer. These sections were used to interpret the location of barriers within the Edwards aquifer. The sections are oriented generally south-southeast, which is approximately normal to both the east-northeast trending Edwards aquifer and the strike of the major faults of the Balcones fault zone. Section lengths represent the distance necessary to cross the aquifer, which is 5 to 40 mi wide. The updip (north) end of the sections are drawn to indicate exposures of the Glen Rose Formation; from there the sections indicate downdip geologic conditions within the freshwater zone and the saline water zone. The sections are approximately parallel and illustrate geologic conditions at 5- to 10-mile intervals. The sections indicate the geologic conditions from near the eastern boundary of the aquifer in Hays County to near the western boundary of the aquifer in Uvalde County. Several sections show places where faults have sufficient vertical displacement to offset the entire, or almost entire, thickness of the aquifer. At these places the faults are barriers to groundwater flow directly downdip across the fault. (Author 's abstract)

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USGS1982

Hydrologic data for urban studies in the San Antonio, Texas, metropolitan area, 1979-80

Hydrologic investigations of urban drainage basins in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Houston, and San Antonio. Studies were completed in the Fort Worth metropolitan area at the end of the 1977 water year, and in the Dallas metropolitan area at the end of the 1979 water year. The Geological Survey, in cooperation with the Texas Department of Water Resources, expanded the existing streamflow network in the San Antonio metropolitan area in May 1968 to begin urban hydrology studies in this area. In September 1968, the program was further expanded to include the collection of water-quality data. The operation and maintenance of stations 08178000, San Antonio River at San Antonio; 08178700, Salado Creek (upper station) at San Antonio; and 08178800, Sal ado Creek (lower station) at San Antonio are funded by the San Antonio River Authority in conjunction with the Texas Department of Water Resources and the U.S. Geological Survey. The operation and maintenance and collection of water-quality data at station 08178720, Lorence Creek at Thousand Oaks Blvd., San Antonio, station 08178640, West Elm Creek at San Antonio, and station 08178645, East Eln Creek at San Antonio, are funded by the Edwards Underground Water District in cooperation with the Texas Department of Water Resources and the U.S. Geological Survey. Station 08178640, West Elm Creek at San Antonio, and station 08178645, East Elm Creek at San Antonio will provide hydrologic data on similar and adjacent watersheds. The West Elm watershed is still predominately rural but is undergoing extensive urbanization in some areas. The East Elm watershed is relatively stable and undeveloped. The objectives of the San Antonio urban hydrology study are: To provide data showing the effects of various stages of urbanization on flood discharge and runoff. To provide water-quality data on surface-water runoff from floods of various magnitudes, during all seasons of the year from areas with different types of urban development. Annual publication of the San Antonio urban studies was initiated in 1969. A defination of terms related to streamflow, water quality, and other hydrologic data, as used in this report, are defined in the U.S. Geological Survey's 1979 and 1980 "Water resources data for Texas" reports.

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USGS1978

Method of estimating natural recharge to the Edwards Aquifer in the San Antonio area, Texas

The method of estimating annual recharge is based on data collected from a network of stream-gaging stations and on assumptions related to applying the runoff characteristics from gaged areas to ungaged areas. The basic approach is a water-balance equation, in which recharge within a stream basin is the difference between measured streamflow above and below the infiltration area of the aquifer plus the estimated runoff in the zone that includes the infiltration area. Recharge in the Medina River basin also includes seepage losses from Medina Lake and Diversion Reservoir. The principal errors in the estimates of annual recharge are related to errors in estimating runoff in ungaged areas, which represent about 30 percent of the infiltration area. The estimated long-term average annual recharge in each basin, however, is probably representative of the actual recharge because the averaging procedure tends to cancel out the major errors.

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USGS1976

Hydrologic data for urban studies in the San Antonio, Texas metropolitan area, 1976

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Dallas, Dallas County, Fort Worth, Houston, and San Antonio. The Geological Survey, in cooperation with the Texas Department of Water Resources, expanded the existing streamflow network in the San Antonio metropolitan area in May 1968 to begin urban hydrology studies in this area. In September 1968, the program was further expanded to include the collection of water-quality data.

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