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Research about Texas

Source-linked reports with geographic coverage including Texas.

At least 1,171 records · Page 65Linked to original sources
USGS1979

Key to the common marine molluscs of Texas

A dichotomous key is developed which provides the investigator a means for identifying the common marine molluscs on the Texas coast. The key is written as to allow the user to stop or begin at any desired taxonomic level (class, order, superfamily, family, genus, species) depending on prior knowledge or specific need (Table 1). Because of the special importance of bivalves to many studies, species-specific information is provided pertaining to feeding type, relation to substrate, and distribution (Table 2). An illustrated glossary is also provided.

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USGS1979

Use of the STORM model for estimating the quantity and quality of runoff from the metropolitan area of Houston, Texas

The "STORM" model, developed by the U.S. Army Corps of Engineers, was selected from existing models and adapted to use available data to compute runoff from the Houston, Texas, area and to compute the loads and concentrations of biochemicaloxygen demand, dissolved solids, total phosphorus, total organic carbon, total nitrogen, and fecal-coliform bacteria. The water-quality data simulated by the STORM model will be used by the Texas Department of Water Resources to refine and verify a model of the Calveston Bay estuarine system. Discharge and precipitation data for the 1975 water year and all available waterquality analyses were used to calibrate the model for the Buffalo, Whiteoak, Brays, Sims, Hunting, Greens, and Vince Bayous. Data for the 1974 water year were used to verify the model for discharge. After verification, the calibrations were adjusted to balance the difference between the 1974 and 1975 error predictions for discharge. The adjusted model was used with records of precipitation and evaporation to simulate a 20-vear record of the quantity and quality of runoff from the modeled area.

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USGS1979

Water quality of Livingston Reservoir on the Trinity River, southeastern Texas

The concentrations of dissolved solids, chloride, and sulfate in Livingston Reservoir on the Trinity River in southeastern Texas usually average less than 250 mg/l (milligrams per liter), 40 mg/l, and 50 mg/l, respectively. The water is usually hard or moderately hard (61 to 180 mg/l as calcium carbonate). The concentrations of principal dissolved constituents in the reservoir are usually maximum during summer and fall when evaporation is high and inflow is low. Thermal stratification of the reservoir usually begins in March and persists until September or October. Neither the seasonal variation of dissolved constituents in inflow to the reservoir nor thermal stratification has resulted in significant stratification of the principal dissolved constituents. However, thermal stratification has resulted in significant seasonal and areal variations of dissolved oxygen, which results in higher concentration of dissolved iron, dissolved manganese, total phosphorus, and total inorganic nitrogen. Oxygen utilized in the stabilization of unoxidized material from upstream sources, decaying algae, and pre-existing organic material along the bottom of the reservoir is not replaced during periods of summer stagnation; and water below depths of 25 to 35 feet (8 to 11 meters) usually contains less than 1.0 mg/l dissolved oxygen. During periods of summer stagnation, reducing conditions often result in the solution of iron and manganese from bottom sediments in the deep parts of the reservoir. At site A C , a deep site near Livingston Dam, dissolved-iron concentrations in water near the bottom of the reservoir during summer have ranged from 80 to 2,300 μg/l (micrograms per liter) and have averaged about 750 μg/l. The concentrations of dissolved manganese in water near the bottom of the reservoir at this site during summer have ranged from 230 to 4,700 μg/l and have averaged about 2,600 μg/l. Water near the surface of the reservoir throughout the year and water near the bottom during periods of winter circulation usually contain less than 100 μg/l of dissolved iron and 100 μg/l of dissolved manganese. The concentrations of total phosphorus and inorganic nitrogen in water near the bottom at deep sites near Livingston Dam are usually maximum during periods of summer stagnation when decay of aquatic organisms and chemical reduction of bottom sediments release phosphorus and nitrogen to the water. The concentrations of phosphorus in the bottom stratum of water at site A C average about 2.0 mg/l. The concentrations of inorganic nitrogen in the bottom and surface strata at this site during summer average about 4.0 mg/l and 0.1 mg/l, respectively. Seasonal temperature and dissolved oxygen cycles have resulted in significant quantities of dissolved iron, dissolved manganese, total phosphorus, and total inorganic nitrogen being trapped and recycled within the reservoir.

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USGS1979

A digital model for simulation of ground-water hydrology in the Houston area, Texas

This report documents the construction and calibration of a digital model for the simulation of hydrologic conditions in the Chicot and Evangeline aquifers in the Houston area of southeastern Texas. The model is a five-layer finite-difference model, with a grid pattern of 63 x 67 nodes representing an area of 27,000 square miles, for simulation of three- dimensional ground-water flow. The hydrologic properties and processes modeled were ground-water withdrawals, transmissivities, storage coefficients of the aquifers and clays, quantity of water derived from storage in the clays, and vertical hydraulic conductivity and vertical leakage. The model, which simulates water-level declines, changes in storage in the clay layers, and land-surface subsidence, was calibrated by use of historical records from 1890 to 1975. It is very sensitive to variations in transmissivities and to variations in water-table and artesian storage. It is less sensitive to variations in clay storage.

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USGS1978

Origin of a South Texas roll-type uranium deposit; I, Alteration of iron-titanium oxide minerals

The detrital Fe-Ti oxide minerals and their authigenic alteration products in samples from cores spanning 1.7 km across a roll-type uranium deposit in the mid-Tertiary Catahoula Tuff, south Texas, record important information on host-rock preparation and on development of the altered tongue of the deposit. In reduced rock, in front of and enveloping the altered tongue, iron disulfide minerals (pyrite and marcasite) have partially to completely replaced titanomagnetite and, to a lesser extent, titanohematite. Subsequent oxidation of these sulfidized Fe-Ti oxides, by processes that formed the altered tongue and uranium roll, produced ferric oxide and hydroxide phases (limonite) pseudomorphous after the sulfides. Fe-Ti oxides 1.0 km updip from the roll front were never sulfidized; titanomagnetite (partly replaced by hematite) and martite constitute nearly half of the heavy mineral fraction and limonite is absent. Oxidized rocks 210 m and closer to the nose of the roll front, however, are nearly devoid of titanomagnetite and contain abundant limonite. The redox interface that bounds the altered tongue, therefore, moved more than 210 m but less than 1.0 km. Detrital Fe-Ti oxide minerals are increasingly sulfidized in the downdip direction indicating that initial sulfidizaton was more intense in that direction. Organic carbon content is uniformly very low throughout the host sandstone, which implies that heterotrophic sulfate-reducing bacteria were not involved in the generation of sulfide. The H 2 S for the initial sulfidization may have been derived from oil and gas in formations that underlie the Catahoula Tuff. The H 2 S probably invaded the Catahoula along a fault that is 1.5 km downdip from the present roll front.

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USGS1978

Origin of a South Texas roll-type deposit; II, Sulfide petrology and sulfur isotope studies

Petrologic and sulfur isotopic studies have been carried out on drill core samples from a roll-type uranium deposit in the mid-Tertiary Catahoula Tuff, Webb County, south Texas. Epigenetic iron disulfide minerals formed in two distinct stages. The first stage involved sulfidization of the host rock by sulfide (H 2 S, HS-)-bearing solutions that emanated from a fault about 1.5 km downdip from and subparallel to the orebody. Pyrite was the dominant iron disulfide mineral formed from this fault sulfide. The isotopic composition (delta 34 S) of first-stage iron disulfide is quite heavy (>0 per mil), in part because the fault-derived H 2 S was isotopically heavy. The development of the second-stage sulfides was related to processes that formed the uranium roll. Iron disulfide minerals produced during this second stage commonly occur as rims around the first-stage sulfides. The rims are exclusively marcasite in and adjacent to ore, but the pyrite content in these rims increases with increasing distance from ore. The sulfur of the second-stage sulfides in the vicinity of the roll front is isotopically light (--25 to --40 per mil). The virtual absence of organic carbon in the host sand precludes a bacterial origin for the ore-stage iron disulfide minerals and, therefore, eliminates bacterial metabolism as the mechanism for isotopic fractionation. Instead, the sulfur source for ore-stage sulfides was preore (first stage) sulfides, remobilized via partial oxidation to soluble metastable sulfur oxyanions.

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USGS1978

A sediment-dispersal model for the South Texas continental shelf, northwest Gulf of Mexico

Textural-distribution patterns of sea-floor sediments on the South Texas continental shelf between Matagorda Bay and the U.S.-Mexico international boundary were evaluated as part of a regional environmental-studies program. Sediment textural gradients support a conceptual model for the regional sediment-dispersal system, which is characterized by both net offshore transport and net south-trending coastwise transport components on a wind-dominated shelf. Coastwise transport results in the net southward migration of both palimpsest sandy mud composing the ancestral Brazos-Colorado delta flank in the northern sector, and modern mud composing the central sector; these migrating sediments are encroaching southward onto immobile relict muddy sands composing the ancestral Rio Grande delta in the southern sector. In the proposed model, the suspension transport of modern silt-enriched mud derived mainly from coastal sources is the dominant dispersal mechanism. Net offshore transport is attributed both to diffusion, and to the advective ebb-tide discharge of turbid lagoonal-estuarine waters from coastal inlets. Net southward transport is attributed mainly to advection by seasonally residual coastwise drift currents reflecting a winter-dominated hydraulic regime. Frequent winter storms characterized by relatively high-speed northerly winds that accompany the passage of cold fronts appear to be dominant regional dispersal agents.

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USGS1978

Factors controlling heavy-mineral variations on the South Texas outer continental shelf, Gulf of Mexico

Heavy-mineral distribution on the outer continental shelf off the southern coast of Texas shows regional variability induced by provenance and local variability reflecting genetic differences in sea-floor sediments. Q-mode factor analysis showed that three suites of heavy minerals are present. The southern ancestral Rio Grande delta sediments contain a distinct opaque-pyroxene-garnet suite, whereas the northern ancestral Brazes-Colorado delta sediments contain a tourmaline-green hornblende suite. An interdelta region contains a heavy mineral suite that is mixed owing to contributions from both ancestral deltas. Analysis of variance, correlation, and regression methods indicate that heavy-mineral variations in each sedimentary province have been significantly influenced by hydraulic fractionation by size, shape, and density, and by a selective chemical decomposition of unstable minerals. These factors have operated at varying degrees on the relict, palimpsest, and modern sediment populations of the sedimentary provinces since the end of Pleistocene time. The differential effects of these processes on the sediments have resulted in local variations that contribute to the total mineralogical variability. A comparison of the heavy mineral suites of the modern and relict Rio Grande delta sediments, which are derived from a common provenance, also shows mineral variations resulting from factors other than provenance.

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USGS1978

Ground-water data for the Salt Basin, Eagle Flat, Red Light Draw, Green River Valley, and Presidio Bolson in westernmost Texas

From October 1971 through October 1974, the U.S. Geological Survey collected ground-water data in the basins in Texas west of the Pecos River drainage area and northwest of the Big Bend country. The basins included are, from east to west: The Presidio Bolson; the Salt Basin; Green River Valley, Eagle Flat, and Red Light Draw. These data, which were collected in cooperation with the Texas Department of Water Resources (formerly Texas Water Development Board), will provide information for a continuing assessment of water availability within the State. The data-collection program consisted of an inventory of all major irrigation, municipal-supply, and industrial wells; selected stock and domestic wells; and selected springs. Water samples were collected from representative wells and springs for chemical analyses. These data, together with data from geophysical surveys and test drilling, will be used to prepare a report on the availability of ground water in the basins of westernmost Texas. Data collected prior to this study are contained in the reports listed in the selected references. The well-numbering system is shown on figure 1, and the locations of the wells, test holes, and springs are shown on figures 2-8. The records of wells and springs are given in table 1, and the water levels in selected observation wells in the Salt Basin are given in table2. The chemical analyses of water samples from selected wells, test holes, and springs are given in table 3.

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USGS1978

Hydrologic data for North Creek, Trinity River basin, Texas, 1976

The U.S. Soil Conservation Service is actively engaged in the installation of flood- and soil-erosion reducing structures in Texas under the authority of "The Flood Control Act of 1936 and 1944" and Watershed Protection and Flood Prevention Act" (Public Law 566), as amended. The Soil Conservation Service has found that approximately 3,500 floodwater-retarding structures would be physically and economically feasible in Texas. As of September 30, 1976, 1,673 (corrected figure) of these structures had been built. This watershed-development program will have varying but important effects on surface- and ground-water resources of river basins, especially where a large number of the floodwater-retarding structures are built. Basic hydrologic data under natural and developed conditions are needed to appraise the effects of the structures on the yield and mode of occurrence of runoff. During the period 1951-62, the U.S. Geological Survey began hydrologic investigations in 12 small watersheds (fig. 1). As of Sept. 30, 1976, data collection in ten of these study areas has been completed and is now in progress in the remaining two. These studies are being made in cooperation with the Texas Water Development Board, the Soil Conservation Service, the San Antonio River Authority, the city of Dallas, and the Tarrant County Control and Improvement District No. 1. The 12 study areas were chosen to sample watersheds having different rainfall, topography, geology, and soils. In five of the study areas (North, Little Elm, Mukewater, Little Pond-North Elm, and Pin Oak Creeks), streamflow and rainfall records were collected prior to construction of the floodwater-retarding structures, thus affording the opportunity for analyses of the conditions "before and after" development. A summary of the development of the floodwater-retarding structures in each study area as of Sept. 30, 1976, is shown in table 1.

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USGS1978

Profiles showing potentiometric surfaces and changes in effective stress in aquifers in Harris and Galveston counties, Texas, 1977-78

These profiles were prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Counties Coastal Subsidence District and the Texas Department of Water Resources to show the changes in the altitudes of the potentiometric surfaces and, consequently, the changes in effective stress on the framework of the aquifers as a result of changes in the distribution and amount of ground-water pumping. In general, and in most areas, the profiles show for the dates indicated that water levels have increased and that the effective stress has decreased.

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USGS1978

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

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 and 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. The objectives of the Austin urban hydrology study are as follows:1. To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume.; 2. To determine the effect of urban development on flood peaks and volume.; 3. To ascertain the variation in water quality for different seasons from selected basins of varying urban development. This report presents the basic hydrologic data collected in the Austin urban area for the 1976 water year (Oct. 1, 1976 to Sept. 30, 1976). To facilitate the pubication and distribution of this report at the earliest feasible time, certain material has been included that does not conform to the formal publication standards of the U.S. Geological Survey.

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