USGS Science⌕ Search

Geology topics

Research about Texas

Source-linked reports with geographic coverage including Texas.

At least 811 records · Page 45Linked to original sources
USGS1996

Techniques to estimate generalized skew coefficients of annual peak streamflow for natural basins in Texas

This report presents two techniques to estimate generalized skew coefficients used for log-Pearson Type III peak-streamflow frequency analysis of natural basins in Texas. A natural basin has less than 10 percent impervious cover, and less than 10 percent of its drainage area is controlled by reservoirs. The estimation of generalized skew coefficients is based on annual peak and historical peak streamflow for all U.S. Geological Survey streamflow-gaging stations having at least 20 years of annual peak-streamflow record from natural basins in Texas. Station skew coefficients calculated for each of 255 Texas stations were used to estimate generalized skew coefficients for Texas. One technique to estimate generalized skew coefficients involved the use of regression equations developed for each of eight regions in Texas, and the other involved development of a statewide map of generalized skew coefficients. The weighted mean of the weighted mean standard errors of the regression equations for the eight regions is 0.36 log 10 skew units, and the weighted mean standard error of the map is 0.35 log 10 skew units. The technique based on the map is preferred for estimating generalized skew coefficients because of its smooth transition from one region of the State to another.

Texas↗
USGS1996

Ground-water quality, water year 1995, and statistical analysis of ground-water-quality data, water years 1994-95, at the chromic acid pit site, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas

The Chromic Acid Pit site is an inactive waste disposal site that is regulated by the Resource Conservation and Recovery Act of 1976. The 2.2-cubic-yard cement-lined pit was operated from 1980 to 1983 by a contractor to the U.S. Army Air Defense Artillery Center and Fort Bliss. The pit, located on the Fort Bliss military reservation in El Paso, Texas, was used for disposal and evaporation of chromic acid waste generated from chrome plating operations. The site was closed in 1989, and the Texas Natural Resources Conservation Commission issued permit number HW-50296 (U.S. Environmental Protection Agency number TX4213720101), which approved and implemented post-closure care for the Chromic Acid Pit site. In accordance with an approved post-closure plan, the U.S. Geological Survey is cooperating with the U.S. Army in monitoring and evaluating ground-water quality at the site. One upgradient ground-water monitoring well (MW1) and two downgradient ground-water monitoring wells (MW2 and MW3), installed adjacent to the chromic acid pit, are monitored on a quarterly basis. Ground-water sampling of these wells by the U.S. Geological Survey began in December 1993. The ground-water level, measured in a production well located approximately 1,700 feet southeast of the Chromic Acid Pit site, has declined about 29.43 feet from 1982 to 1995. Depth to water at the Chromic Acid Pit site in September 1995 was 284.2 to 286.5 feet below land surface; ground-water flow at the water table is assumed to be toward the southeast. Ground-water samples collected from monitoring wells at the Chromic Acid Pit site during water year 1995 contained dissolved- solids concentrations of 481 to 516 milligrams per liter. Total chromium concentrations detected above the laboratory reporting limit ranged from 0.0061 to 0.030 milligram per liter; dissolved chromium concentrations ranged from 0.0040 to 0.010 milligram per liter. Nitrate as nitrogen concentrations ranged from 2.1 to 2.8 milligrams per liter; nitrite plus nitrate as nitrogen concentrations ranged from 2.4 to 3.2 milligrams per liter. Water samples from wells MW1 and MW2 were analyzed for volatile organic compounds for the first quarter; no confirmed volatile organic compounds were detected above laboratory reporting limits. Detected chemical concentrations in water from the chromic acid pit monitoring wells during the four sampling periods were below U.S. Environmental Protection Agency-established maximum contaminant levels for public drinking-water supplies. Overall, water-quality characteristics of water from the chromic acid pit ground-water monitoring wells are similar to those of other wells in the surrounding area. Statistical analyses were performed on 56 of the chemical constituents analyzed for in ground water from the chromic acid pit monitoring wells. Concentrations of chloride, fluoride, sulfate, and potassium were significantly less in water from one or both downgradient wells than in water from the upgradient well. Concentrations of nitrate as nitrogen, nitrite plus nitrate as nitrogen, and dissolved solids were significantly greater in water from the downgradient wells than in water from the upgradient well. Concentrations of nitrate as nitrogen, chloride, and potassium were significantly different in water from the two downgradient wells. Statistical analysis of chemical constituents in water from the chromic acid pit monitoring wells did not appear to indicate a release of hazardous chemicals from the chromic acid pit. There was no indication of ground-water contamination in either downgradient well.

Texas↗
USGS1996

Measurement of flows for two irrigation districts in the lower Colorado River basin, Texas

The Lower Colorado River Authority sells and distributes water for irrigation of rice farms in two irrigation districts, the Lakeside district and the Gulf Coast district, in the lower Colorado River Basin of Texas. In 1993, the Lower Colorado River Authority implemented a water-measurement program to account for the water delivered to rice farms and to promote water conservation. During the rice-irrigation season (summer and fall) of 1995, the U.S. Geological Survey measured flows at 30 sites in the Lakeside district and 24 sites in the Gulf Coast district coincident with Lower Colorado River Authority measuring sites. In each district, the Survey made essentially simultaneous flow measurements with different types of meters twice a day once in the morning and once in the afternoon at each site on selected days for comparison with Lower Colorado River Authority measurements. One-hundred pairs of corresponding (same site, same date) Lower Colorado River Authority and U.S. Geological Survey measurements from the Lakeside district and 104 measurement pairs from the Gulf Coast district are compared statistically and graphically. For comparison, the measurement pairs are grouped by irrigation district and further subdivided by the time difference between corresponding measurements less than or equal to 1 hour or more than 1 hour. Wilcoxon signed-rank tests (to indicate whether two groups of paired observations are statistically different) on Lakeside district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological Survey measurements are not statistically different. The median absolute percent difference between the flow measurements is 5.9 percent; and 33 percent of the flow measurements differ by more than 10 percent. Similar statistical tests on Gulf Coast district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological Survey measurements are not statistically different. The median absolute percent difference between the flow measurements is 2.6 percent; and 30 percent of the flow measurements differ by more than 10 percent. The differences noted above between Lower Colorado River Authority and U.S. Geological Survey measurements with 1 hour or less between measurements and the differences between essentially simultaneous U.S. Geological Survey measurements are of similar orders of magnitude and, in some cases, very close.

Texas↗
USGS1996

Geologic framework and hydrogeologic characteristics of the Edwards aquifer outcrop (Barton Springs segment), northeastern Hays and southwestern Travis Counties, Texas

The hydrogeologic subdivisions within the Barton Springs segment of the Edwards aquifer outcrop in northeastern Hays and southwestern Travis Counties generally are porous and permeable. The most porous and permeable appear to be hydrogeologic subdivision VI, the Kirschberg evaporite member of the Kainer Formation; and hydrogeologic subdivision III, the leached and collapsed members, undivided, of the Person Formation. Hydrogeologic subdivision II, the cyclic and marine members, undivided, of the Person Formation, also is quite porous and permeable in Hays County. The porosity of the rocks in the Edwards aquifer outcrop is related to depositional or diagenetic elements along specific stratigraphic horizons (fabric selective) and to dissolution and structural elements that can occur in any lithostratigraphic horizon (not fabric selective). Permeability depends on the physical properties of the rock such as pore size, shape, distribution, fissuring, dissolution, and interconnection of pores and vugs. The Edwards aquifer rocks that crop out in the Barton Springs segment of the Edwards aquifer generally have the same lithologic characteristics as the Edwards aquifer rocks that crop out in Comal and southwestern Hays Counties. However, in the northeastern part of the segment in Travis County, the rock unit that is apparently equivalent to the basal nodular member of the Kainer Formation is called the Walnut Formation. Because the units appear to be stratigraphically and lithologically equivalent, the basal nodular member is used instead of the Walnut Formation for this report. Essentially all of hydrogeologic subdivision II, which is about 70 feet thick in Hays County, is missing in Travis County. In the Barton Springs segment of the Edwards aquifer, the aquifer probably is most vulnerable to surface contamination in the rapidly urbanizing areas on the Edwards aquifer outcrop. Contamination can result from spills or leakage of hazardous materials; or runoff on the intensely faulted and fractured, karstic limestone outcrops characteristic of the recharge zone.

Texas↗
USGS1996

Seagrass responses to long-term light reduction by brown tide in upper Laguna Madre, Texas: Distribution and biomass patterns

A brown tide caused by a very dense bloom of an as yet undescribed species of the new class Pelagophyceae was first reported in upper Laguna Madre, Texas, USA, in June 1990 and has been there continuously through December 1995. No change in response to reduced light was evident in the distribution of the seagrass Halodule wrightii along transects sampled before the brown tide in 1988 and resampled after initiation of the brown tide in 1991 and 1992; however, in winter 1993-94 losses were documented over 2.6 km 2 of bottom and by winter 1994-95 the area of vegetation lost had more than tripled to 9.4 km 2 . Changes in biomass presaged the changes in distribution. Decreases in biomass at depths >1.4 m were evident 2 yr before bare areas were detected. Reductions in biomass were more pronounced toward the south, in keeping with a gradient of increasing light attenuation from north to south. Support of a diminishing number of new shoots by reclamation of nutrients and stored reserves from senescing shoots and rhizomes may allow H. wrightii to persist under conditions of insufficient light for periods greatly in excess of the life span of any one shoot. This postulated capability would account for the pattern of diminishing biomass over time where the seagrass persists in deeper areas and the long lag between light reduction and change in distribution where the seagrass succumbed.

Texas↗
USGS1996

Biomass patterns in seagrass meadows of the Laguna Madre, Texas

The Laguna Madre of Texas supports the most extensive seagrass meadows in the western Gulf of Mexico, In 1988 seagrasses covered 730 km 2 or about three-quarters of the embayment. Halodule wrightii dominated the entire upper laguna, and total biomass was quite uniform near 160 g˙m -2 throughout. Four species shared dominance in the lower laguna. Where present mean biomass of Thalassia testudinum was 373 g˙m -2 ; Syringodium filiforme , 138 g˙m -2 ; Halodule wrightii , 78 g˙m -2 ; and Halophila engelmannii , 6 g˙m -2 . Macroalgae were widespread, at 71 g˙m -2 where present. Halodule wrightii was dominant and biomass was low on sand flats of the barrier island separating the laguna from the gulf. Halophila engelmannii was limited to the deep edges of meadows. Biomass >300 g˙m -2 was limited to one extensive T. testudinum meadow at the south end of the laguna at all vegetated depths and two small areas with S. filiforme dominant at intermediate depths. Laguna Madre was similar in biomass to the two regions of extensive development of seagrasses in the eastern gulf: the Big Bend region of Florida (Iverson and Bittaker, 1986) and Florida Bay (Iverson and Bittaker, 1986; Zieman, et al., 1989). The laguna differed from the eastern gulf sites in more turbid waters and much shallower maximum depths of occurrence of seagrasses (<2 m compared to 8–11 m), higher contribution of H. wrightii to system-wide biomass (although H. wrightii 's share has rapidly diminished in Laguna Madre as it has been displaced by S. filiforme and T. testudinum [Quammen and Onuf, 1993]), and much higher macroalgal biomass (limited to the section of the lower laguna receiving agricultural inflows). Similarities in the environments of Laguna Madre and inner Florida Bay suggest that, if cover and biomass of Thalassia continue to increase, the laguna may become vulnerable to mass mortalities as are now occurring in Florida Bay.

Texas↗
USGS1995

Landscape change and its effects on the wintering range of a lesser snow goose Chen caerulescens caerulescens population: A review

The Texas coast has experienced considerable urban, industrial, and agricultural growth during the 20th Century. The region provides important wintering habitat to many avian species, including lesser snow geese Chen caerulescens caerulescens . This paper draws the biological and ecological fields into an historical perspective by examining available literature on the development of the upper Texas coast and range changes of lesser snow geese. Historically, lesser snow geese wintered in the coastal marshes, but expanded their range into the adjacent prairies in the mid-1900s. Winter range expansion was negatively affected by urban and industrial encroachment in the coastal marshes and positively influenced by agricultural development in the prairies, which increased dramatically during World War II. The lesser snow goose population flourished alongside some human-induced landscape alterations. However, projected declines in agriculture and increased urbanization of prairie and coastal marsh habitats may result in significant negative effects on the lesser snow goose population.

Texas↗
USGS1995

Floods in southeast Texas, October 1994

Rainfall in southeast Texas, which ranged in amounts from about 8 to more than 28 inches during October 15&ndash;19, 1994, caused severe flooding in parts of a 38-county area. A combination of meteorological events&mdash;residual atmospheric moisture over southern Texas associated with Hurricane Rosa from the Pacific Coast of Mexico and low-level moisture from the Gulf of Mexico drawn inland to a warm front by a strong low-pressure system over the southern Rocky Mountains&mdash;spawned vigorous thunderstorms that produced rainfall amounts that may exceed records for the area.

Texas↗
USGS1995

National Water-Quality Assessment Program— Pesticides in the Trinity River Basin study unit, Texas, 1968-91

The Trinity River Basin National Water Quality Assessment (NAWQA) study-unit staff began assessment activities in 1991, and in 1992, undertook a retrospective review of existing data on pesticides. The main purpose of this review was to aid in the design of a pesticide-sampling network for the study unit. The review consisted of the compilation, screening, and analysis of available pesticide-sample information. In addition, important environmental factors, which influence the occurrence and distribution of pesticides in the study unit, were identified and compiled. A report of this review and analysis will be released in 1995 (Ulery and Brown, in press). This fact sheet provides a brief overview of significant findings.

Texas↗
USGS1995

Water-quality assessment of the Trinity River Basin, Texas—Data collection, 1992–95

Assessment activities in the Trinity River Basin study unit of the National Water-Quality Assessment (NAWQA) Program began in October 1991 with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks. In October 1993, a 3-year intensive data-collection program was initiated. Guidelines were provided by the NAWQA Program National Synthesis team, and suggestions for networks and surveys were made by the study unit&rsquo;s liaison committee. This fact sheet describes the data-collection activities.

Texas↗
USGS1995

National Water-Quality Assessment Program; summary of pesticide data collected on East Fork Double Bayou, near Anahuac, Texas, March to September 1994

The Trinity River Basin study-unit assessment began in October 1991, with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks, surveys, and studies. Then, a 3-year intensive data-collection program was initiated. The assessment followed guidelines provided by the National Water-Quality Assessment (NAWQA) Program National Synthesis team and considered suggestions made by the study unit's liaison committee. One of the issues selected for study concerned the quality of runoff in the coastal prairie. The study includes collecting streamflow, water-quality and watershed data on three streams, each representing watersheds in different parts of the coastal prairie. This fact sheet presents a summary of the pesticide data collected on East Fork Double Bayou from March to September 1994.

Texas↗
USGS1995

National Water-Quality Assessment Program; summary of pesticide data collected on Whites Bayou near Anahuac, Texas, March to September 1994

One water-quality monitoring site was established on Whites Bayou, at the downstream end of the study area. Sampling began in March 1994 and will continue for 1 year. Sampling frequency ranges from four times per month in May and June to once per month in July. Stream-stage measurements were made three times per week from April to September. Field measurements during sampling include stream stage and discharge, water temperature, pH, dissolved oxygen, and specific conductance. Laboratory analyses include major inorganic ions, nutrients, sediment, and pesticides.

Texas↗
USGS1995

National Water-Quality Assessment Program; summary of pesticide data collected on West Prong Old River near Dayton, Texas, March to September 1994

The Trinity River Basin study-unit assessment began in October 1991, with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks, surveys, and studies. Then, a 3-year intensive data-collection program was initiated. The assessment followed guidelines provided by the National Water-Quality Assessment (NAWQA) Program National Synthesis team and considered suggestions made by the study unit's liaison committee. One of the issues selected for study concerned the quality of runoff in the coastal prairie. The study includes collecting streamflow, water-quality, and watershed data on three streams, each representing watersheds in different parts of the coastal prairie. This fact sheet presents a summary of the pesticide data collected on West Prong Old River from March to September 1994.

Texas↗
USGS1995

Water Quality Assessment of the Trinity River Basin, Texas - Pesticides in a Suburban Watershed, Arlington, 1993-94

The Trinity River Basin was among the first 20 hydrologic systems under full inplementation of the National Water Quality Assessment (NAWQA) Program. Planning and analysis of existing information began in 1991. Intensive water-quality data collection began in 1993. As a part of the NAWQA Program, pesticide samples were taken from surface water, ground water, streambed sediment, and aquatic-organism tissue in the Rush Creek watershed in Arlington, Texas, during 1993?94.

Texas↗
USGS1995

Water-quality assessment in the Trinity River Basin, Texas; pesticide occurrence in streams, winter and spring 1994

A consistent, basin-wide set of data for streams in the Trinity River Basin is necessary to provide a baseline for current conditions, to compare with historical data, and to provide a reference for future studies by the National Water-Quality Assessment (NAWQA) Program. In addition, the basin-wide surveys begin the process of addressing the cause-effect relation for water quality in the basin. Effects of land use, geology, vegetation, soils, and reservoirs on water quality were considered by site selection. Seasonal differences were addressed by conducting two surveys, the first during the winter low-flow period and the second during the late spring high-flow period.

Texas↗
USGS1995

Flood frequency in Texas; calculation of peak-streamflow frequency at gaging stations

In 1991, the U.S. Geological Survey (USGS) began a 5-year study of floods in Texas. The study, which is being done in cooperation with the Texas Department of Transportation, uses streamflow data collected at streamflow-gaging stations to assess Texas flood characteristics. Two major objectives of the study are to determine for unregulated, rural basins (1) the most reliable method to calculate peak-streamflow frequency for Texas stations; and (2) a method to estimate peak-streamflow frequency at any Texas stream site (gaged or ungaged) using pertinent peak-streamflow information from nearby stations. This fact sheet pertains to the first objective of the study.

Texas↗