Geology topics

Research about Austin, Texas

Source-linked reports with geographic coverage including Austin, Texas.

At least 19 recordsLinked to original sources

USGS2023

Seed banks of rare Physostegia correllii (Lamiaceae) in Lady Bird Lake, Austin, Texas, U.S.A.

Rare species threatened by climate and land-use change may harbor seeds in soil seed banks for periods of time even if adults have disappeared from the site. Soil samples were collected from sites with current Phyostegia correllii populations and from sites with former populations in Lady Bird Lake (a reservoir of the Colorado River, Austin, Texas. A seedling emergence study was conducted under greenhouse conditions, and the presence/absence of seedling emergence was recorded for two years. Seeds germinated from the seed banks of all current and former colonies tested. The presence of seed banks in a historical site (Blunn Creek) of Physostegia correllii suggests that management to encourage the germination of seeds might help to encourage the establishment of populations of this species. The re-establishment of disturbance fugitives might be facilitated by removing overhanging ground vegetation or imposing water management regimes that mimic natural floodplain dynamics.

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USGS2022

Community-powered urban stream restoration: A vision for sustainable and resilient urban ecosystems

Urban streams can provide amenities to people living in cities, but those benefits are reduced when streams become degraded, potentially even causing harm (disease, toxic compounds, etc.). Governments and institutions invest resources to improve the values and services provided by urban streams; however, the conception, development, and implementation of such projects may not include meaningful involvement of community members and other stakeholders. Consequently, project objectives may be misaligned with community desires and needs, and projects may fail to achieve their goals. In February 2020, the 5 th Symposium on Urbanization and Stream Ecology, an interdisciplinary meeting held every 3 to 5 y, met in Austin, Texas, USA, to explore new approaches to urban stream projects, including ways to maximize the full range of potential benefits by better integrating community members into project identification and decision making. The symposium included in-depth discussion about 4 nearby field case studies, participation of multidisciplinary urban stream experts from 5 continents, and input from the Austin community. Institutional barriers to community inclusion were identified and analyzed using real-world examples, both from the case studies and from the literature, which clarified disparities in power, equity, and values. Outcomes of the symposium have been aggregated into a vision that challenges the present institutional approach to urban stream management and a set of strategies to systematically address these barriers to improve restoration solutions. Integrating community members and other stakeholders throughout the urban restoration process, and a transparent decision-making process to resolve divergent objectives, can help identify appropriate goals for realizing both the ecological and social benefits of stream restoration.

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USGS2014

PAH concentrations in lake sediment decline following ban on coal-tar-based pavement sealants in Austin, Texas

Recent studies have concluded that coal-tar-based pavement sealants are a major source of polycyclic aromatic hydrocarbons (PAHs) in urban settings in large parts of the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of coal-tar sealants. We evaluated the effect of Austin’s ban by analyzing PAHs in sediment cores and bottom-sediment samples collected in 1998, 2000, 2001, 2012, and 2014 from Lady Bird Lake, the principal receiving water body for Austin urban runoff. The sum concentration of the 16 EPA Priority Pollutant PAHs (∑PAH 16 ) in dated core intervals and surficial bottom-sediment samples collected from sites in the lower lake declined about 44% from 1998–2005 to 2006–2014 (means of 7980 and 4500 μg kg –1 , respectively), and by 2012–2014, the decline was about 58% (mean of 3320 μg kg –1 ). Concentrations of ∑PAH 16 in bottom sediment from two of three mid-lake sites decreased by about 71 and 35% from 2001 to 2014. Concentrations at a third site increased by about 14% from 2001 to 2014. The decreases since 2006 reverse a 40-year (1959–1998) upward trend. Despite declines in PAH concentrations, PAH profiles and source-receptor modeling results indicate that coal-tar sealants remain the largest PAH source to the lake, implying that PAH concentrations likely will continue to decline as stocks of previously applied sealant gradually become depleted.

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USGS2005

Acoustic doppler velocity monitoring within Main Spring, Barton Springs, Austin, Texas, April-September 2004-enhancing the accuracy of springflow data

Acoustic Doppler velocity (ADV) meters are sophisticated underwater monitoring instruments that use sound waves to measure water velocity in as many as three directions. In April 2004, an ADV meter was installed inside the principal orifice and discharge point of Main Spring at Barton Springs in Austin, Texas. This instrument collects velocity data that can be used to enhance the accuracy of springflow data and identify previously unrecognized hydrologic patterns. An accurate record of springflow at Barton Springs is important for several reasons. First, Barton Springs is the only known habitat for the Barton Springs salamander ( Eurycea sosorum ), a federally-listed endangered species that is dependent on reliable springflow to survive. Determination of sustainable Edwards aquifer yields compatible with the survival of the species is impossible without an accurate springflow record. Second, the 3-acre swimming pool fed by Barton Springs is enjoyed by about 340,000 people per year (2003) and is an important tourist attraction. Third, Barton Springs provides a part of Austin's municipal water supply; water from Barton Springs discharges into Town Lake on the Colorado River about 0.4 mile upstream from one of Austin's three water-supply plants. Fourth, flow in Barton Springs reflects water levels in the Barton Springs segment of the Edwards aquifer, which currently (2005) is designated a sole-source aquifer by the U.S. Environmental Protection Agency. This report, prepared by the U.S. Geological Survey, briefly summarizes the results of recent ADV-based velocity and springflow data acquisition at Barton Springs and describes an application of velocity monitoring to enhance the accuracy of springflow data.

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USGS2004

Concentrations of polycyclic aromatic hydrocarbons (PAHs) and major and trace elements in simulated rainfall runoff from parking lots, Austin, Texas, 2003

Samples of creek bed sediment collected near seal-coated parking lots in Austin, Texas, by the City of Austin during 2001–02 had unusually elevated concentrations of polycyclic aromatic hydrocarbons (PAHs). To investigate the possibility that PAHs from seal-coated parking lots might be transported to urban creeks, the U.S. Geological Survey, in cooperation with the City of Austin, sampled runoff and scrapings from four test plots and 13 urban parking lots. The surfaces sampled comprise coal-tar-emulsion-sealed, asphalt-emulsion-sealed, unsealed asphalt, and unsealed concrete. Particulates and filtered water in runoff and surface scrapings were analyzed for PAHs. In addition, particulates in runoff were analyzed for major and trace elements. Samples of all three media from coal-tar-sealed parking lots had concentrations of PAHs higher than those from any other types of surface. The mean total PAH concentration in particulates in runoff from parking lots in use were 3,500,000, 620,000, and 54,000 micrograms per kilogram from coal-tar-sealed, asphalt-sealed, and unsealed (asphalt and concrete combined) lots, respectively. The probable effect concentration sediment quality guideline is 22,800 micrograms per kilogram. The mean total PAH (sum of detected PAHs) concentration in filtered water from parking lots in use was 8.6 micrograms per liter for coal-tar-sealed lots; the one sample analyzed from an asphalt-sealed lot had a concentration of 5.1 micrograms per liter and the one sample analyzed from an unsealed asphalt lot was 0.24 microgram per liter. The mean total PAH concentration in scrapings was 23,000,000, 820,000, and 14,000 micrograms per kilogram from coal-tar-sealed, asphalt-sealed, and unsealed asphalt lots, respectively. Concentrations of lead and zinc in particulates in runoff frequently exceeded the probable effect concentrations, but trace element concentrations showed no consistent variation with parking lot surface type.

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USGS2003

Quality of sediment discharging from the Barton Springs system, Austin, Texas, 2000-2002

Four spring outlets of the Barton Springs system provide the only known habitat for the Barton Springs salamander ( Eurycea sosorum ), a federally listed endangered species. After heavy rainfall, sediment is flushed through the Barton Springs segment of the Edwards aquifer and springflow often becomes turbid (cloudy). Sediment in urban areas often has high concentrations of hydrophobic contaminants, such as DDT, polycyclic aromatic hydrocarbons (PAHs), and lead. In response to concerns that sediment discharging from the Barton Springs outlets could contain contaminants at levels that pose a threat to the health of the salamander or its prey, the U.S. Geological Survey (USGS), in cooperation with the U.S. Fish and Wildlife Service, collected samples of suspended sediment discharging from each of the four spring outlets after two rainstorms and analyzed them for a suite of hydrophobic contaminants.

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USGS1999

Town Lake bottom sediments : a chronicle of water quality changes in Austin, Texas, 1960-98

Town Lake, the last in the chain of Highland Lakes on the Colorado River, runs through the center of Austin, Texas. On any given day, grebes and coots dot the water, rowers skim alongside, and the sparkle of the sun on the water can be admired from the adjacent hike and bike path and from the windows of nearby office buildings. During the summer months, crowds gather along the shores of Town Lake to watch as many as 1 million Mexican Free-Tail bats emerge from under the Congress Avenue bridge. But below the lazily moving azure water lies a bed of sediment about 1 meter (m) thick?sediment that has been deposited gradually since the reservoir was formed in 1959 and that has been recording changes in water quality since that time. What can this sediment tell us about the history of water quality in the Colorado River? And what does it say about the effects of the rapid urbanization of Austin and the future health of our environment?

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USGS1987

Hydrologic data for urban studies in the Austin metropolitan area, Texas, 1985

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, and Houston. Studies have been completed in the Dallas, Fort Worth, and San Antonio areas. The Geological Survey, in cooperation with the Texas Department of Water Reources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones Fault Zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representative watersheds with various types of urban development. To quantitatively appraise the ground-water resources of the Edwards aquifer in hydraulic circulation with Barton Springs, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the aquifer. This report presents the basic hydrologic data collected in the Austin urban area for the 1985 water year (Oct. 1, 1984 to Sept. 30, 1985). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-85-3, 1985.

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USGS1987

Effects of runoff controls on the quantity and quality of urban runoff at two locations in Austin, Texas

Rapid urban development in the Austin metropolitan area, Texas, is causing concern about increasing peak discharges from storm runoff and the degradation of the quality of water in receiving streams, lakes, and aquifers. In an attempt to decrease peak discharges and improve water quality, runoff controls are being required in some watersheds. This report summarizes the precipitation, streamflow, and water-quality data collected from September 1982 to September 1984 upstream and downstream from runoff controls at two locations, and presents the effects of these runoff controls on streamflow and the quality of runoff water. The two controls are a detention and filtering pond near Barton Creek Square Shopping Center, a large shopping center southwest of downtown Austin, and a grass-swale control in the Al ta Vista Planned Unit Development, a multipie-family housing area. At Barton Creek Square Shopping Center, rainfall for the storms analyzed ranged from 0.14 to 2.88 inches. The rainfall rate for the September 7, 1983, storm exceeded the 100-year return period for the 5- and 10-minute duration and was equal to the 50-year return period for the 15-minute duration. Peak discharge at the inflow station to the detention pond was closely related to the maximum rainfall during a 5-minute period and occurred about 10 minutes later. The maximum inflow at this station was 185 cubic feet per second and appeared to be the limit of the storm sewer system. For small- and moderate-sized storms, the runoff is contained in the detention pond and passes through a filter system. Runoff from large storms overflows into the drop outlet. For storms contained in the pond, peak discharges at the outflow station generally were less than 3.1 cubic feet per second. As time passed, the outflow peak discharges tended to decrease as a result of reduced permeability of the filter. Cleaning the filter appeared to increase the peak flows but did not restore them to the previous level. The runoff-rainfall ratio averaged 0.85 at the inflow station and 0.36 at the outflow station. A water budget shows unexplained losses to average 20 percent. At the Barton Creek Square Shopping Center, discharge-weighted densities of fecal-col iform and fecal-streptococci bacteria and discharge-weighted concentrations of biochemical oxygen demand, chemical oxygen demand, total organic carbon, suspended solids, total ammonia plus organic nitrogen, and total phosphorus generally were larger in the inflow than in the outflow. Discharge-weighted concentrations of dissolved lead, dissolved iron, and dissolved zinc generally were small in both the inflow and outflow; however, the larger discharge-weighted concentrations of these constituents generally were found in the inflow. Discharge-weighted concentrations of volatile dissolved solids were smaller in the inflow than in the outflow for 10 of the 22 storms analyzed. Discharge-weighted concentrations of total nitrite plus nitrate nitrogen and dissolved solids generally were much smaller in the inflow than in the outflow. It is likely that organic and ammonia nitrogen trapped in the pond from previous storms and in the inflow water as it flows through the pond is being oxidized to nitrite and nitrate nitrogen. Similarly, dissolved solids retained in the filter or on the bed of the pond from previous storms are being leached to the outflow. Measured peak concentrations or densities of most constituents in the inflow were significantly larger than those in the outflow for most constituents. An exception was noted for concentrations of total nitrite plus nitrate which were larger in the outflow than the inflow as indicated by discrete sample analysis for six storms. Loads of most constituents and total numbers of bacteria were significantly larger in the inflow than in the outflow. The total numbers of bacteria were reduced by approximately 80 percent. Average removal efficiencies for suspended solids, biochemical oxygen demand, total phosphorus, total organic carbon, chemical oxygen demand, and dissolved zinc ranged between 60 and 80 percent. The average loads of dissolved solids were approximately 13 percent larger in the outflow than the inflow. Average loads of total nitrite plus nitrate nitrogen were approximately 110 percent larger in the outflow than in the inflow. The increase in loads of these constituents is due to material being leached from the bed of the pond or from the filter system. At Al ta Vista, rainfall for the storms analyzed ranged from 0.25 to 2.00 inches. The maximum rainfall intensity was 0.30 inch for a 5-minute interval. The runoff-rainfall ratio averaged 0.42 and appeared to be evenly distributed about the mean ratio line. The peak discharge at the inflow station to the grass-covered swale area was 0.93 cubic foot per second. Inaccuracies of discharge at the outflow station and variations in the ungaged drainage area with the size of the storm prevented a hydrologic analysis of the basin above this station. Discharge-weighted concentrations of total phosphorus were larger in the outflow than in the inflow for each of the 19 storms analyzed. Discharge-weighted concentrations of dissolved solids, volatile dissolved solids, biochemical oxygen demand, chemical oxygen demand, and total organic carbon were larger in the outflow than in the inflow for at least 12 of the 19 storms analyzed. Discharge-weighted densities of fecal streptococci were decreased between the inflow and outflow, with discharge-weighted densities of fecal streptococci being less in the outflow for 15 of the 19 storms analyzed. Because of the relatively small variations in concentrations and densities of constituents between the inflow and outflow sites, and because of the errors in discharge at the outflow gage, it is not feasible to determine the effect of the grass-covered swales on discharge-weighted concentrations and densities of water-quality constituents. Discrete concentrations or densities of most constituents were not decreased. Peak concentrations of dissolved solids in the outflow exceeded peak concentrations in the inflow for all five of the storms analyzed with discrete samples. Peak concentrations of suspended solids, total ammonia plus organic nitrogen, total nitrite plus nitrate nitrogen, total nitrogen, and dissolved iron were larger in the outflow than in the inflow for four of the five storms analyzed. Load-removal efficiencies of water-quality constituents could not be determined because of inaccuracies in measuring discharge at the outflow site,

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USGS1986

Hydrologic data for urban studies in the Austin metropolitan area, Texas, 1984

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, and Houston. Studies have been completed in the Dallas, Fort Worth, and San Antonio areas. The Geological Survey, in cooperation with the Texas Department of Water Reources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones Fault Zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representative watersheds with various types of urban development. To quantitatively appraise the ground-water resources of the Edwards aquifer in hydraulic circulation with Barton Springs, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the aquifer. This report presents the basic hydrologic data collected in the Austin urban area for the 1984 water year (Oct. 1, 1983 to Sept. 30, 1984). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-84-3, 1984.

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USGS1986

Hydrology and water quality of the Edwards Aquifer associated with Barton Springs in the Austin area, Texas

Urban development over the Edwards aquifer in the Austin, Texas, area has caused concerns about the availability and quality of water in the aquifer. The study area, the Edwards aquifer that discharges to Barton Springs, includes parts of Travis and Hays Counties and extends from the city of Kyle to the Colorado River. A large part of the aquifer lies within the Austin metropolitan area one of the fastest growing areas in the Nation. As of 1985, only about 30,000 people used water from the aquifer, however, according to recent official city of Austin population projections, about 86,000 more people will be living in the study area by the year 2000, many of whom will depend upon the aquifer for water. Barton Springs, which discharges from the aquifer, serves as a supplemental source of drinking water for Austin and as a major recreational attraction. The aquifer is a karst system composed of limestone and dolomite of Cretaceous age. The water occurs in solution channels in the Edwards and Georgetown Limestones. Yields of adjacent wells often differ by as much as four orders of magnitude. Storage within the aquifer is about 306,000 acre-feet, of which about 31,000 acre-feet is within the "transient" part of storage the change in volume occurring between high flow and the lowest known flow of Barton Springs. The average specific yield of the aquifer is 0.017. Within the study area, the Edwards aquifer covers 155 square miles, of which about 151 square miles discharge to Barton Springs, and the remaining 4 square miles discharge to Cold and Deep Eddy Springs. The westernmost 79 percent of the aquifer is under water-table conditions, and the remaining 21 percent is under confined conditions. Three geologic sections are presented in the report, as well as maps showing the altitudes of the base and the top of the Edwards aquifer. Recharge occurs predominantly along faults and fractures crossing six creeks in the recharge area, which covers the westernmost 90 square miles of the aquifer. Leakage probably occurs into the Edwards aquifer from the underlying upper Trinity aquifer. A small amount of subsurface recharge also occurs as "bad-water" encroachment during lovnflow periods. Monthly values for water levels, total surface-water recharge, and total discharge (springflow and pumpage) for the aquifer are available for 4 years. Water-budget analyses show that surface recharge and ground-water discharge (springflow and pumpage) are reasonably balanced, suggesting that the ground-water system is in dynamic equilibrium. Based on 65 years of measurements, Barton Springs has a long-term mean discharge of 50 cubic feet per second and a minimum and maximum discharge of 10 and 166 cubic feet per second. As of 1982, the estimated total ground-water pumpage of about 3,800 acre-feet per year represented just over 10 percent of the average annual discharge of 36,000 acre-feet to Barton Springs. Increased pumpage associated with future ground-water development could reduce the discharge at Barton Springs and reduce ground-water availability. Substantial pumpage increases could cause increased subsurface flow into the aquifer in the form of "bad-water" encroachment, leakage from underlying aquifers, or both. Water-quality data for 1979-83 are available for each creek that recharges the aquifer, from Barton Springs, and for 38 wells. Water quality from Barton Springs and the wells is better than the creeks providing surface recharge, which have fecal-bacteria values as high as 100,000 colonies per 100 milliliters. Significant densities of fecal bacteria have been found in water from Barton Springs. Significant concentrations of nitrate nitrogen, fecal-group bacteria, and fluoride have been identified in samples from wells. Fluoride originates in the aquifers that underlie the Edwards aquifer. Nitrate nitrogen and fecal-group bacteria originate in residential developments and cattle ranches located in the area.

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USGS1986

The effects of urbanization on floods in the Austin metropolitan area, Texas

The effects of urbanization on flood peaks in streams in the Austin metropolitan area were studied in two separate analyses. In the first analysis, annual peak discharge records at 13 streamflow-gaging sites were used to compute a recorded flood frequency relation for each site. Rainfall and streamflow data for 10 to 20 storms for each of these sites were used to calibrate a rainfall-runoff model in which a 55-year rainfall record was used to simulate 55 annual peak discharges. These simulated discharges also were used to develop a flood-frequency relation at each site. The flood-frequency relations from recorded and generated data were then combined by weighting the recorded flood frequency by the years of record at each site to produce a combined (or weighted) flood frequency at each site. Flood frequencies for all 13 sites were subsequently regressed against basin characteristics at each site to determine possible effects of urbanization. The regression analysis of the combined flood-frequency data for the 13 sites yielded an equation for estimating floods of a given recurrence interval at ungaged sites in the Austin area as a function of the contributing drainage area, the total impervious area percentage, and basin shape. The regression equation estimates that a near fully developed hypothetical drainage basin (impervious area percentage, 45) would have discharges for the 2- and 100-year recurrence interval that are 99 percent and 73 percent greater, respectively, than discharges for those frequencies from a rural drainage basin (impervious percentage, 0). In the second analysis, records at one streamflow-gaging site on Waller Creek were analyzed for changes in rainfall-runoff and flood-frequency relations due to urbanization. Annual peak discharges from 1956 to 1980 and data from a total of 80 storms at the Waller Creek site were analyzed. Both analyses showed increases comparable to those predicted using the equations developed from the 13-station analysis. The last 14 years of record (the near fully developed land-use stage for the Waller Creek analysis) at the two sites on Waller Creek were part of the 13-station analysis.

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USGS1985

Hydrologic data for urban studies in the Austin, Texas, metropolitan area, 1983

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, and Houston. Studies have been completed in the Dallas, Fort Worth, and San Antonio areas. The Geological Survey, in cooperation with the Texas Department of Water Reources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones Fault Zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representative watersheds under various types of urban development. To quantitatively appraise the ground-water resources along the Balcones Fault Zone, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the Edwards aquifer that is in hydrologic circulation with Barton Springs. This report presents the basic hydrologic data collected in the Austin urban area for the 1983 water year (Oct. 1, 1982 to Sept. 30, 1983). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-83-3, 1983.

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USGS1985

Simulation of the flow system of Barton Springs and associated Edwards Aquifer in the Austin area, Texas

A digital model of two-dimensional groundwater flow was used to estimate the hydraulic properties of the Edwards Aquifer in a 151 sq mi area near Austin, Texas. The transmissivity, hydraulic conductivity, and specific yield were estimated for the part of the aquifer that discharges at Barton Springs in Austin. The aquifer is composed of the Edwards and overlying Georgetown Limestones of Cretaceous age and ranges in thickness from about 100 ft to about 450 ft. More than 60 years of discharge measurements and 5 years of gaged discharge for Barton Springs were used to adjust springflow for the simulations. Barton Springs accounts for about 96% of springflow from the study area and 90% of the total discharge. The remaining discharge was pumpage from wells which was entered in the model. Four years of gaged recharge were used in the simulations. The potentiometric surfaces used by the models were constructed from water level measurements in as many as 75 wells. The transmissivity was calibrated through steady-state simulations that used the mean value of recharge and mean potentiometric surface to represent average conditions for the aquifer. The transmissivities vary from about 100 sq ft/day in the western part of the aquifer to > 1 million sq ft/day near Barton Springs. Specific yield was calibrated through transient-state simulations for 5 consecutive months using time-dependent data for recharge, discharge, and water levels. The mean specific yield for the aquifer is 0.014 and ranges from 0.008 to 0.064. Additional aquifer properties used in the simulations include storage coefficient, altitudes of the base and top of the aquifer, and hydraulic conductivity. A simulation for the year 2000 using projected pumping rates for municipal, industrial, agricultural, and domestic supplies indicates that the aquifer would be dewatered in the southwestern part of the study area and have large declines in the southeastern part of the study area. Another simulation of projected conditions using potential recharge enhancement predicts a rise in the potentiometric surface of about 50 feet in the southwestern part of the aquifer and moderate water-level declines in the southeastern part of the aquifer.

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USGS1982

Flood of May 24-25, 1981, in the Austin, Texas, metropolitan area

Hydrologic data pertaining to the magnitude and areal extent of flooding that occurred on May 24-25, 1981, along Shoal, Walnut, and Little Walnut Creeks in the Austin, Texas, metropolitan area are presented in this atlas. The flood boundary maps and other flood data provide a technical data base for land-use planning.

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USGS1982

Hydrologic data for urban studies in the Austin, Texas, metropolitan area, 1980

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, Houston, and San Antonio. Studies have been completed in the Dallas and Fort Worth areas. The Geological Survey, in cooperation with the Texas Department of Water Resources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones fault zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representatives watersheds under various types of urban development. To quantitatively appraise the ground-water resources along the Balcones fault zone, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the Edwards aquifer that is is hydrologic circulation with Barton Springs. This report presents the basic hydrologic data collected in the Austin urban area for the 1980 water year (Oct. 1, 1979 to Sept. 30, 1980). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-80-3, 1980.

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USGS1981

Hydrologic data for urban studies in the Austin, Texas, metropolitan area, 1979

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USGS1980

Hydrologic data for urban studies in the Austin, Texas metropolitan area, 1978

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. 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, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations and the collection of water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones Fault Zone.

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