Geology topics

Research about Texas

Source-linked reports with geographic coverage including Texas.

At least 55 records · Page 3Linked to original sources

USGS2025

Texas coastal wetland surface elevation static survey campaign report

Surface elevation data along the Texas Coast is limited, despite having some of the highest rates of relative sea-level rise in the country (Sweet et al., 2022). To narrow these knowledge and data gaps, the U.S. Fish and Wildlife Service (USFWS) established the first landscape-scale rod surface elevation table (RSET) monitoring project aimed at examining surface elevation dynamics of coastal marshes in Texas (Moon et al., 2022). The project, conducted cooperatively between the USFWS and the U.S. Geological Survey (USGS), has focused on 14 coastal marsh sites located within five National Wildlife Refuges (Figure 1). The main objective of this project’s RSET data collection is to quantify the impacts of sea-level rise on coastal properties owned by the USFWS and similar surrounding areas. Data from RSETs will be used to determine areas that are at the greatest risk for potential habitat loss and degradation by examining subsidence and accretion rates. However, for the RSET data to be tied into the national vertical datum of 1988 (NAVD88) and, therefore, linked to the relative sea-level change calculations, it is necessary to establish primary vertical control at each study site through highly accurate and precise global navigation satellite systems (GNSS) surveys. Having a clear methodology for standardization is important for quality data. This report focuses on the methods, with particular emphasis on post-processing, used to survey benchmarks for the RSET data collection along the Texas Coast for the USFWS. Furthermore, this report serves as a general reference guide on the technical aspects of performing and processing GNSS surveys within the Texas coastal refuges to maintain quality and consistency.

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USGS2025

Mortality of fledged whooping cranes in the Aransas-Wood Buffalo Population

Maintaining accurate mortality records for endangered species is important for guiding management and conservation actions. Mortalities of whooping cranes ( Grus americana ) in the Aransas-Wood Buffalo Population (AWBP) are documented in published records from 1950 through 2010. This paper documents publicly available records of known mortalities from 2011 through 2023, and updates historic records from 1950 to 2010. Public sightings and telemetry carcass records were restricted to fledged whooping cranes from the AWBP and stratified by confirmed, suspected, and unknown causes across the annual range (i.e., summer, migration, and winter). This mortality update provides more certainty associated with available carcass data and reduces discrepancies in existing published information.

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USGS2025

Stream gauge network assessment

The purpose of this chapter is to assess the current (2023) performance and capabilities of the streamgauge network installed for the “Evaluate Improved Streamflow Measurement Technologies at TxDOT Bridges” project. The U.S. Geological Survey (USGS) traditionally employs a method of discharge computation relating continuously measured stage to an associated discharge (Rantz and others, 1982). This stage-discharge relation is built using numerous physical discharge measurements, which is labor-intensive. A primary research objective of this project is to evaluate the feasibility of methods alternative to the traditional USGS stage-discharge relation for computing discharge, namely the computation of discharge using surface velocimetry.

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USGS2024

The 3D Elevation Program—Supporting the Texas economy

Introduction High-resolution elevation data for Texas inform decision making to improve the State’s economy. Existing elevation data coverage is used to improve resiliency to natural disasters, manage energy infrastructure, and assess natural resources. The expanding availability of current and more accurate elevation data helps better support natural resources conservation, agriculture and precision farming, flood risk management, infrastructure and construction management, geologic resource assessment and hazard mitigation, coastal zone management, and identification of features of interest or concern, such as archaeological and historic sites. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed three-dimensional (3D) model of the Earth’s surface and aboveground features. The 3D Elevation Program (3DEP) is managed by the U.S. Geological Survey (USGS) in partnership with Federal, State, Tribal, U.S. territorial, and local agencies to acquire consistent lidar coverage at quality level 2 or better to meet the many needs of the Nation and Texas. The status of available and in-progress 3DEP baseline lidar data in Texas is shown in figure 1. 3DEP baseline lidar data include quality level 2 or better, 1-meter or better digital elevation models, and lidar point clouds, and must meet the Lidar Base Specification version 1.2 ( https://www.usgs.gov/3dep/lidarspec ) or newer requirements. The National Enhanced Elevation Assessment identified user requirements and conservatively estimated that availability of lidar data would result in at least $53.1 million in new benefits annually to the State. The top 10 Texas business uses for 3D elevation data, which are based on the estimated annual conservative benefits of 3DEP, are shown in table 2.

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USGS2024

Viability modeling for decision support with limited data: A lizard case study

Plateau spot-tailed earless lizards, Holbrookia lacerata, are a species of ground lizard in central Texas that are under review for listing as endangered under the US Endangered Species Act, but heretofore no predictive models of population dynamics or viability have been developed. We used limited available data and published demographic rates in a PVA model to predict future status of these lizards under parametric and ecological uncertainty and temporal variability. Even in cases where data are sparse and life history information are limited, viability models can help clarify the consequences of management choices given the uncertainty. Our model predicted that on average populations will decline in in the future. Quasi-extinction probability was low 20 years into the future but up to 0.60. Extinction risk was highly dependent on the road mortality effect and the proportion of the population exposed to roadways, both of which are currently uncertain quantities. Despite these unknowns, our model enables managers to consider the future abundance and extinction risk for the species and make decisions about management to project the populations and also identifies key uncertainties for future research and monitoring.

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USGS2024

Geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Medina County, Texas

During 2023–24, the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, revised a previous publication of the geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers that was completed during 2018–20 within northern Medina County, Texas. The purpose of this report is to present the updated geologic framework and hydrostratigraphy of the rocks containing the Edwards and Trinity aquifers in northern Medina County from field observations of the surficial expressions of the rocks. The report includes a detailed 1:24,000-scale hydrostratigraphic map with names and descriptions of the geologic and hydrostratigraphic units (HSUs) in the study area. This study includes updates to the geology of the Kainer Formation (or its stratigraphic equivalent, the Fort Terrett Formation) with the addition of a burrowed unit between the basal nodular and dolomitic members. The hydrostratigraphy was also updated with the addition of HSU IIA for the upper part of the Devils River Limestone and the Seco Pass HSU for the burrowed member of the Kainer (or Fort Terrett) Formation. The Cretaceous age rocks (listed in ascending order) in the study area are part of the Trinity Group, Edwards Group and stratigraphically equivalent Devils River Limestone, Washita Group, Eagle Ford Group, Austin Group, and Taylor Group, with isolated areas where Late Cretaceous age igneous rocks have intruded. The groups and formations are composed primarily of relatively thick layers of clays, shales, and limestone. The igneous rocks are coarse-grained ultramafic in composition. Hydrostratigraphically, the rocks exposed in the study area (listed in descending order from land surface) are igneous, the upper confining unit to the Edwards aquifer, the Edwards aquifer, the upper zone of the Trinity aquifer, and the upper part of the middle zone of the Trinity aquifer. The karstic carbonate Edwards and Trinity aquifers developed because of their original depositional history, primary and secondary porosity, diagenesis, fracturing, and faulting. These factors have resulted in development of modified porosity, permeability, and transmissivity within and between the aquifers.

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USGS2024

Sod farms drive habitat selection of a migratory grassland shorebird during a critical stopover period

Migratory shorebirds are one of the fastest declining groups of North American avifauna. Yet, relatively little is known about how these species select habitat during migration. We explored the habitat selection of Buff-breasted Sandpipers ( Calidris subruficollis ) during spring and fall migration through the Texas Coastal Plain, a major stopover region for this species. Using tracking data from 118 birds compiled over 4 years, we found Buff-breasted Sandpipers selected intensively managed crops such as sod and short-stature crop fields, but generally avoided rangeland and areas near trees and shrubs. This work supports prior studies that also indicate the importance of short-stature vegetation for this species. Use of sod and corn varied by season, with birds preferring sod in spring, and avoiding corn when it is tall, but selecting for corn in fall after harvest. This dependence on cropland in the Texas Coastal Plain is contrary to habitat use observed in other parts of their non-breeding range, where rangelands are used extensively. The species' almost complete reliance on a highly specialized crop, sod, at this critical stopover site raises concerns about potential exposure to contaminants as well as questions about whether current management practices are providing suitable conditions for migratory grassland birds.

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USGS2024

Effects of release strategy, source population, and age on reintroduced scaled quail reproduction

Translocation is one strategy to reestablish populations of scaled quail ( Callipepla squamata ). Initial reproductive success post-translocation is important for establishing short-lived species such as quail, but factors influencing reproductive success are poorly understood. We evaluated the effect of source population and variation in delayed release strategy (1−9 weeks) on nest initiation and nest survival of wild-caught, translocated scaled quail. We trapped and translocated scaled quail in 2016–2017 from source populations in the Edwards Plateau and Rolling Plains ecoregions of Texas, USA, to a large contiguous (>40,000 ha) release site in Knox County, Texas. We used a multi-state mark-recapture model with state uncertainty to test for effects of release treatment, source population, age, release location, and year on nest initiation and survival. Increased length of holding time decreased re-nesting effort. Yearlings were more likely to initiate nests than adults and the probability of re-nesting was lower during the year with drought conditions. There was no effect of source population on any of the parameters we evaluated. Future scaled quail reintroduction efforts may benefit from prioritizing translocation of yearlings and conducting translocations when drought conditions are not forecasted.

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USGS2024

Review of the life history and conservation of federally endangered plant species of the Lower Rio Grande Valley, Texas, U.S.A.

This review aims to summarize information critical to the conservation of the federally listed endangered species of South Texas, which occur along the border of Texas and Mexico. This paper describes the characteristics, habitat, population status, distribution, life history, threats, and restoration of endangered plant species of the Lower Rio Grande Valley, Texas, which includes Cameron, Willacy, Hildago, and Starr County. Seven federally listed species are considered including Ambrosia cheiranthifolia, Asclepias prostrata, Astrophytum asterias, Ayenia limitaris, Manihot walkerae, Lesquerella thamnophila (syn. Physaria thamnophila), and Thymophylla tephroleuca. An eighth species, Physostegia correllii is under consideration for federal listing by the U.S. Fish and Wildlife Service. This paper assembles information on the background, biological status, major threats, and conservation to aid managers and the scientific community in restoring and managing these species.

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USGS2024

Management implications of habitat selection by whooping cranes (Grus americana) on the Texas coast

Effective habitat management for rare and endangered species requires a thorough understanding of their specific habitat requirements. Although machine learning models have been increasingly used in the analyses of habitat use by wildlife, the primary focus of these models has been on generating spatial predictions. In this study, we used machine learning models in combination with simulated management actions to guide planning and inform managers. We used data from 61 whooping cranes ( Grus americana ) tagged with GPS telemetry collars between 2009 and 2018 near Aransas National Wildlife Refuge in coastal Texas. We included variables based on topography, land use classification, vegetation height, plant phenology, drought, storm surge events, and both wild and prescribed fires. We then built models at multiple scales: population level, home range level, and roosting and daytime within home range level. We simulated responses to the two primary management actions used to enhance whooping crane habitat on Aransas National Wildlife Refuge: prescribed fire and removal of woody vegetation. At the population and home range scales, land use classification variables had the highest importance values, whereas the combined elevation and bathymetry layer was the most important predictor at both roosting and daytime within home range scales. Our findings revealed that the effects of fire, although generally modest, varied spatially. Areas dominated by estuarine wetlands exhibited higher predicted use within the first months after a fire, whereas those dominated by palustrine wetlands were more likely to be avoided in the immediate postfire years. Our simulation of vegetation removal identified the areas on Aransas National Wildlife Refuge where whooping cranes were predicted to benefit the most if vegetation were removed. These techniques can be used by other researchers wanting to examine and predict the effects of potential management actions on target species habitat.

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USGS2024

Land-use and land-cover change in the Lower Rio Grande Ecoregions, Texas, 2001–2011

Urban growth and other land-use changes were examined in the Lower Rio Grande Valley and Alluvial Floodplain ecoregions in Texas, along the U.S.-Mexico border. The analysis focused on understanding the types and causes of land change as well as the recovery of natural land-cover types between years 2001 and 2011. The purpose was to develop improved capabilities for understanding land change dynamics in urbanizing ecoregions and to provide data for further analyses. The spatial data, including metadata, allows further exploration and characterization of changes affecting this dynamic region.

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USGS2024

Spatial distribution of API gravity and gas/oil ratios for petroleum accumulations in Upper Cretaceous strata of the San Miguel, Olmos, and Escondido Formations of the south Texas Maverick Basin—Implications for petroleum migration and charge history

The Maverick Basin of south Texas is currently undergoing active exploration and production of gas and oil from tight sandstone reservoirs. The most productive tight sandstones in the basin are in the Upper Cretaceous San Miguel, Olmos, and Escondido Formations. These units are second only to the Eagle Ford Shale in terms of cumulative production volumes. The structural history of the Maverick Basin, from rifting to subsidence to exhumation, has had a profound effect on the characteristics of these reservoirs and the petroleum resources contained therein. This U.S. Geological Survey review of the production history of these strata reflects a recent shift from conventional production to horizontal drilling (unconventional) that exploits low permeability reservoirs in previously overlooked areas of existing oil and gas fields in southern Texas, typically outside of established field boundaries. To investigate the physical properties of the Maverick Basin hydrocarbon accumulations, this case study compiled American Petroleum Institute (API) gravity measurements and calculated cumulative gas/oil ratios (GOR) for thousands of producing wells from the San Miguel, Olmos, and Escondido Formations. Maps were generated from the compiled well production data to show the spatial heterogeneity of API gravity and GOR values for the three formations within the Maverick Basin and immediately outside the basin to the northeast. Within the Maverick Basin, the spatial patterns of API gravity values indicate lighter oils downdip towards the southern basin edge. GOR values indicative of wet and dry gases within the basin are seen interspersed, with values that correspond to black and heavy oils. Differences in the spatial patterns of the petroleum properties within the Maverick Basin are interpreted as effects of Eocene basin inversion caused by Laramide orogenic deformation, and the resulting reservoir exhumation of basin strata. East of the Maverick Basin, spatial distributions of API gravity and GOR values show progressively heavier oils updip to the northwest, grading to dry gases downdip to the southeast, which correlates to the oil and gas windows of the underlying Eagle Ford Shale. Correlation of API gravity and GOR values from the San Miguel, Olmos, and Escondido Formations with thermal maturity data from the Eagle Ford Shale suggests that the Eagle Ford Shale is the petroleum source, and that petroleum migration was approximately vertical for areas to the east of the Maverick Basin. The discontinuity of API gravity and GOR properties within the Maverick Basin implies a complex petroleum charge history, possibly involving the remigration of petroleum and the addition of petroleum from other source intervals in Mexico, to the southwest. Depressurization of exhumed, overpressured reservoirs of the San Miguel, Olmos, and Escondido Formations can explain the intermittent occurrence of gas production throughout the southern Maverick Basin by exsolution of gas from formation brines and the resulting dry gas flushing of hydrocarbon-charged reservoirs. The introduction of dry gas through flushing can, in turn, explain why the patterns of API gravity and GOR values are so dissimilar in the Maverick Basin. This process has implications for possible future production of unconventional resources from undiscovered tight-gas reservoirs in strata of the San Miguel, Olmos, and Escondido Formations, and a different approach to petroleum exploration may be needed in the Maverick Basin relative to exploration techniques applied in other basins within the northern Gulf of Mexico.

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USGS2024

Geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within parts of Bandera and Kendall Counties, Texas

The karstic Edwards and Trinity aquifers are classified as major sources of water in south-central Texas by the Texas Water Development Board. During 2019–23 the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, mapped and described the geology and hydrostratigraphy of the rocks composing the Edwards and Trinity aquifers within parts of Bandera and Kendall Counties from field observations of the surficial expressions of the rocks. The thicknesses of the mapped lithostratigraphic and hydrostratigraphic units were also estimated from field observations in the study area. The Cretaceous rocks in the study area are part of the Trinity Group and Edwards Group. The groups, formations, and members are composed primarily of layers of marls, shales, and limestones. The limestones are composed of mudstone through grainstone, framestone and boundstone, dolomite, and argillaceous and evaporitic rocks. The principal structural feature in the study area is the Balcones fault zone. The Balcones fault zone is the result of late Oligocene and early Miocene extensional faulting and fracturing that was a result of the eastern Edwards Plateau uplift. In the Balcones fault zone, most of the faults in the study area are high-angle to vertical, en echelon, normal faults that are predominantly downthrown to the southeast. Hydrostratigraphically, the rocks exposed in the study area are those that contain the Edwards aquifer, the upper zone of the Trinity aquifer, and the middle zone of the Trinity aquifer. Descriptions of the hydrostratigraphic units, thicknesses, hydrologic function, porosity types, and field identification and observations are provided, including those for the informal Bandera and Love Creek hydrostratigraphic units of the Edwards aquifer, which were identified through the mapping for this study.

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USGS2024

Status of water-level altitudes and long-term and short-term water-level changes in the Chicot and Evangeline (undifferentiated) and Jasper aquifers, greater Houston area, Texas, 2023

Since the early 1900s, groundwater withdrawn from the primary aquifers that compose the Gulf Coast aquifer system—the Chicot, Evangeline, and Jasper aquifers—has been an important source of water in the greater Houston area, Texas. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of water-level altitudes and water-level changes in these aquifers in the greater Houston area. In this report, the Chicot and Evangeline aquifers are treated as a single aquifer for the purposes of providing annual assessments of regional-scale water-level altitudes and water-level changes over time. In 2023, shaded depictions of water-level altitudes for the Chicot and Evangeline aquifers (undifferentiated) ranged from about 286 feet (ft) below the North American Vertical Datum of 1988 (NAVD 88) to about 169 ft above NAVD 88. The largest decline in water-level altitudes indicated by the 1977–2023 long-term water-level-change map was in south-central Montgomery County southeast of The Woodlands. In comparison, the 1990–2023 long-term water-level-change map depicts the largest declines in water-level altitudes in localized areas at or near certain wells in parts of northwestern Harris County and south-central Montgomery County. The largest rise in water-level altitudes for 1977–2023 is depicted in a relatively large area in southeastern Harris County, whereas the largest rise in water-level altitudes for 1990–2023 is depicted in a relatively large area in central Harris County. The 5-year short-term water-level-change map depicts the largest declines at three wells in northern Fort Bend County, one well in western Harris County, and three wells in south-central Montgomery County and the largest rise at one well in central Harris County. The 1-year short-term water-level-change map depicts the largest declines at one well in northern Fort Bend County and two wells in southwestern Harris County and the largest rises at one well in northern Brazoria County and one well in south-central Montgomery County. In 2023, shaded depictions of water-level altitudes for the Jasper aquifer ranged from about 242 ft below NAVD 88 to about 218 ft above NAVD 88. The 2000–23 long-term water-level-change map depicts water-level declines throughout the study area where water-level-measurement data from the aquifer were collected, with the largest declines in north-central Harris County and south-central Montgomery County south of The Woodlands. The 5-year short-term water-level-change map depicts the largest declines at two wells in central Montgomery County near Conroe and two wells in south-central Montgomery County southeast of The Woodlands and the largest rise at one well in western Montgomery County. The 1-year short-term water-level-change map depicts the largest declines at four wells in south-central Montgomery County southeast of The Woodlands and one well in central Montgomery County near Conroe and the largest rises at two wells in western Montgomery County.

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USGS2024

Examining water and proppant demand, and produced water production, associated with petroleum resource development in the Eagle Ford Group, Texas

More than 20,000 horizontal wells have been drilled and hydraulically fractured in the Eagle Ford Group since the discovery well in 2008, but a considerable amount of undiscovered petroleum remains. Recently, drilled wells have been hydraulically fractured with an average of nearly 13 million gallons of water and 16 million lb of sand, yielding a million or more gallons of produced water. To inform future petroleum development in the Eagle Ford, the U.S. Geological Survey (USGS) conducted a water and proppant assessment using a geology-based approach that builds on the 2018 USGS assessment of undiscovered technically recoverable petroleum. Using probabilistic input values and a Monte Carlo simulation, we determined that production of the remaining undiscovered technically recoverable oil and gas in the Eagle Ford Group would require approximately 687,565 Mgal (millions of gallons) of water and 839,702,000,000 lb of proppant (both are mean values of output distributions). This possible future petroleum production would also include 176,817 Mgal (mean value) of produced formation water. On average, oil wells require water volumes that are approximately twice the volume of oil that will be produced, and Eagle Ford gas wells require approximately 5.21 Mgal of water per billion cubic feet of gas (bcfg). Produced formation water volumes are approximately 60% of the produced oil volume and, for gas wells, will yield approximately 1 Mgal formation water per bcfg. Understanding the water and proppant requirements associated with petroleum exploration and the resulting volume of produced water can inform decisions regarding the future of Eagle Ford development.

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USGS2024

Mapping Arundo donax (Arundo cane) with multispectral imagery before, during, and after herbicide treatment along the Rio Grande in Webb County, Texas, 2020–21

Arundo donax , commonly called Arundo cane, giant reed, or Carrizo cane, is an invasive bamboo-like perennial grass common in riparian areas throughout the southwestern United States. In Texas, not only does it negatively affect riparian ecosystems, but it has also become a problem for border security because it reduces visibility along the Rio Grande. To address these problems, in 2015 the Texas State Soil and Water Conservation Board was authorized by the Texas State Legislature to develop a program to eradicate Arundo cane along the Rio Grande. In 2020, the Texas State Soil and Water Conservation Board applied imazapyr and glyphosate herbicides along a 19.3-kilometer reach of the Rio Grande, northwest of Laredo, Texas. The U.S. Geological Survey, in cooperation with the Texas State Soil and Water Conservation Board and the Webb Soil and Water Conservation District, used WorldView-3 Standard high-resolution satellite imagery to map Arundo cane extent along the reach before , during , and after the herbicide-treatment period on June 30, 2020, September 26, 2020, and May 7, 2021, respectively. A maximum likelihood supervised classification analysis was computed on the images to map the spatial extent and estimate the area covered by Arundo cane. The estimated area covered by Arundo cane in the before classification was 1,282,000 square meters, in the during classification was 1,064,000 square meters, and in the after classification was 1,108,000 square meters. The qualitative comparison of the three images shows that there was an overall decrease in vegetation classified as Arundo cane throughout the study area.

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USGS2024

Hyperspectral (VNIR-SWIR) analysis of roll front uranium host rocks and industrial minerals from Karnes and Live Oak Counties, Texas Coastal Plain

VNIR-SWIR (400–2500 nm) reflectance measurements were made on the surfaces of various cores, cuttings and sample splits of sedimentary rocks from the Tertiary Jackson Group, and Catahoula, Oakville and Goliad Formations. These rocks vary in composition and texture from mudstone and claystone to sandstone and are known host rocks for roll front uranium occurrences in Karnes and Live Oak Counties, Texas. Spectral reflectance profiles, 569 in total, were reduced to 125 representative spectral signatures, which were analyzed using the U.S. Geological Survey's (USGS) Material Identification and Characterization Algorithm (MICA). MICA uses an automated continuum-removal procedure together with a least-squares linear regression to determine the fit of observed sample spectral absorption features to those of reference mineral standards in a spectral library. The reference minerals include various clay, mica, carbonate, ferric and ferrous iron minerals and their mixtures. In addition, absorption feature band-depth analysis was done to identify rock surfaces exhibiting absorption features related to uranium and zeolite minerals, which were not included in the command files used to execute MICA. Rocks from each of the four geologic units produced broadly similar spectral signatures as a result of comparable mineral compositions, but there were some notable differences. For example, Ca- and Na-montmorillonite was matched most frequently to the spectral absorption features in 2-μm (∼2000–2500 nm) wavelengths, while goethite occurred often at 1-μm (∼400–1000 nm) wavelengths. The latter is related to limonitic iron-staining in and around oxidized zones of the uranium roll front as described in previous papers. Rocks of the Jackson Group differed from those of the Catahoula, Oakville and Goliad units in that the former exhibited spectral features we interpret as being due to the presence of lignite-bearing mudstone layers. Goliad rocks exhibit spectral features related to dolomite, gypsum, anhydrite, and an unidentified green clay mineral that is possibly glauconite . Jackson Group rocks also exhibit weak but well-resolved absorption features at 964 and 1157 nm related to either or both zeolite minerals clinoptilolite and heulandite. These zeolite minerals and a few spectra exhibiting hydrous silica absorption features are indicative of alteration of volcanic glass in tuffaceous mudstone and claystone layers. A few sample spectra exhibited strong absorption features at around 1135 nm related to the uranium mineral coffinite. Both the 1135 nm coffinite and 1157 nm zeolite absorption features overlap somewhat, potentially making them difficult to distinguish without additional hyperspectral field, laboratory or remote sensing data. The results of this study were compared to mixtures of minerals described for ore, gangue and alteration minerals in deposit models for sandstone-hosted uranium, sedimentary bentonite and sedimentary zeolite. Use of these spectra can help facilitate mapping of both waste materials from the legacy mining of the above commodities, as well as future exploration and resource assessment activities.

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USGS2024

Hydrologic changes in the Brazos River Basin and implications for Great Plains fishes

Alteration of natural flow regimes from surface water and groundwater resource development has adversely impacted aquatic habitats of resident fish throughout the Great Plains. Two endangered cyprinids, Sharpnose Shiner Notropis oxyrhynchus and Smalleye Shiner N. buccula , were historically found throughout the Brazos River Basin in Texas. However, their range has been greatly reduced by construction of impoundments and stream depletion from groundwater pumping. Successful recruitment requires flowing, unobstructed river reaches of sufficient velocity to suspend semi-buoyant fertilized fish ova. The wide, shallow stream habitats the shiners utilize are now limited to the Upper Brazos River Basin upstream of Possum Kingdom Reservoir. This study assesses the relative importance of long-term climate variability, reservoir construction, and groundwater development on Upper Brazos streamflow regimes by (1) calculating flow metrics (2) evaluating groundwater-surface water interactions and long-term groundwater inflows, and (3) using mixed-effects regression models and Poisson regression. Results show that fish habitat has been threatened through several impacted hydrologic processes: (1) groundwater development has resulted in reduced mean daily flows, peak flows, and zero-flow days, (2) upstream impoundments have increased zero-flow days and reduced mean daily flows, and (3) lower mean daily flows and peak flows now occur during droughts, suggesting water resource development—particularly after 1970—has exacerbated drought effects. We illustrate this approach using the Upper Brazos River Basin; however, the methodology applied can inform management actions to maintain spawning flows for streams in similar altered basins.

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