396 research outputs found
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Surface fissures in the Hueco Bolson and adjacent basins, West Texas
No full textBureau Publication GC9202 - to purchase a print copy please go to: https://store.beg.utexas.edu/geologic-circulars/520-gc9202.html Research funded by the Texas Low-Level Radioactive Waste Disposal Authority under Interagency Contract Number IAC(90-91)0268Surface fissures have been observed in many desert basins in the western United States. These surface-collapse features are usually discovered after a normally dry surface has been covered with water, either by runoff from intense rainfall, by flooding, or by irrigation. Their sudden appearance attracts the attention of local residents, especially when the fissures render unpaved roads impassable. Collapse features begin as near-surface tension fractures that are enlarged by erosion and piping. Uneroded tension fractures are typically 0.1 to 7.6 cm wide and are filled with fine-grained sediment. Surface-collapse features may coalesce to form fissures, some up to 15 km long. Maximum reported depth of fissures or fractures is 25 m. Most tension fractures have formed where ground water has been pumped and water levels have dropped significantly (30 to 140 m). However, some fractures exist where no substantial pumping has occurred and no corresponding drop in water tables has been recorded. These features may have formed as a result of the lowering of ground water over geologic time. Tensional stress leading to fracture formation may result from differential compaction of unconsolidated sediments over bedrock irregularities or abrupt sedimentary facies boundaries or from desiccation. Seismic activity, although not a prerequisite for formation of collapse features, in some instances may trigger the development of tension fractures. Near-surface tension fractures may remain undetected until they are enlarged by piping and the surface above them collapses. Polygonal and branching patterns of fissures suggest desiccation as a cause of fracture genesis, but this origin remains unproven.
Fissures at the Hueco Bolson study area in western Texas are located on a flat-lying alluvial slope on Cenozoic sediments that fill a small basin in Cretaceous bedrock. The basin is separated from the main part of the Hueco Bolson by the Campo Grande fault. All three fissures at the Hueco Bolson study area are in topographic lows, indicating that overland flow is important to their development. The conditions necessary for piping to occur probably exist in the study area only in topographic lows during and after heavy rains.
Detailed study of fractures reveals that walls of fractures that underlie fissures match across each fracture's midline, evidence of simple tensional separation. These fractures are filled with silty, clayey sediment that contains vertical, clayey laminae, suggesting multiple periods of filling or fracturing or both. Fracture fill conducts water more readily than surrounding sediments, as seen at fissure 1. Low chloride concentrations down to 4.6 m below the surface near this fissure indicate that relatively high moisture fluxes occur there, compared with moisture fluxes in sediments in ephemeral stream channels and on low-lying interfluves. Unlike in fissured areas elsewhere in the desert Southwest, there has been no significant ground-water pumping in the vicinity of the study area. However, four factors have led to lower ground-water levels in the study area over geologic time: incision of the Rio Grande, change to a warmer, drier climate, fault movement on the Campo Grande fault, and preferential drainage of relatively permeable basin fill beneath the study area. These fissures and those that form where ground water has not been pumped are natural geomorphic features of the desert Southwest.Bureau of Economic GeologyUT Librarie
Amarillo National Resource Center for Plutonium
No full textThis report was prepared with the support of the U.S. Department of Energy (DOE) Cooperative Agreement No. DEFC04 -95AL85832. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the author(s) and do not necessarily reflect the views of DOE. This work was conducted through the Amarillo National Resource Center for Plutonium. This page intentionally left blank. ANRCP-1999-14 AMARILLO NATIONAL RESOURCE CENTER FOR PLUTONIUM/ A HIGHER EDUCATION CONSORTIUM A Report on Recharge Monitoring in an Interplaya Setting Bridget R. Scanlon, Robert C. Reedy, and Jinhuo Liang Bureau of Economic Geology The University of Texas at Austin Austin, Texas 78712 Submitted for publication to ANRC Environmental Program March 1999 This page intentionally left blank. i
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Assessing linkages between climate teleconnections and freshwater inflows to Texas bays and estuaries
No full textUnderstanding spatiotemporal variability in freshwater inflows to the bays and estuaries along the Gulf of Mexico is critical for water resources management to maintain the health of the ecosystem and marine life. The objective of this study was to assess linkages between climate teleconnections (e.g. El Nino Southern Oscillation [ENSO], North Atlantic Oscillation [NAO], and Pacific Decadal Oscillation [PDO]), precipitation, and freshwater inflows to the Gulf of Mexico. Seasonal Trend Decomposition using LOESS (STL) analysis was used to decompose monthly precipitation and freshwater inflows (1941-2015) to each bay and estuary, isolating long-term variability, and comparing it to ENSO during warm and cool PDO phases and NAO. Results show that there are moderately strong positive correlations between ENSO and precipitation (R = 0.37 to 0.7) with mostly higher precipitation during El Nino and lower precipitation during La Nina. These correlations were weakened during PDO warm phase (R = 0.16 to 0.41) and amplified during PDO cool phase (R = 0.66 to 0.8). Temporal variability in precipitation was linked to bay and estuary freshwater inflows, showing high flows during El Nino and low flows during La Nina. Additionally, there are moderately strong positive correlations between NAO and freshwater inflows to two of the 10 bays/estuaries in the northeast (Sabine-Neches and Trinity San Jacinto, R = 0.45 and 0.41). These correlations tend to occur within the year of the driving conditions in the Pacific and Atlantic oceans. Identifying these linkages and the corresponding response times can help predict and manage the hydrologic response to wet and dry climate cycles linked to climate teleconnections along the Texas Gulf Coast to help protect and maintain the health of the vital estuarine environmentsEnergy and Earth Resource
The food-energy-water nexus: Transforming science for society
No full textEmerging interdisciplinary science efforts are providing new understanding of the interdependence of food, energy, and water (FEW) systems. These science advances, in turn, provide critical information for coordinated management to improve the affordability, reliability, and environmental sustainability of FEW systems. Here we describe the current state of the FEW nexus and approaches to managing resource conflicts through reducing demand and increasing supplies, storage, and transport. Despite significant advances within the past decade, there are still many challenges for the scientific community. Key challenges are the need for interdisciplinary science related to the FEW nexus; ground-based monitoring and modeling at local-to-regional scales; incorporating human and institutional behavior in models; partnerships among universities, industry, and government to develop policy relevant data; and systems modeling to evaluate trade-offs associated with FEW decisions
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Dissolved noble gases in groundwater
No full texttextAtmospheric noble gases (He, Ne, Ar, Kr, and Xe) dissolved in groundwater are a valuable tool in hydrology. Numerous studies have relied on groundwater recharge temperatures calculated from dissolved noble gas data (noble gas temperatures, NGT) to infer paleoclimate conditions. This research investigated gas dissolution during groundwater recharge and critically examined the use of dissolved noble gas data in groundwater research. A detailed investigation of an agriculturally impacted shallow aquifer allowed comparison of measured water table temperatures (WTT) with calculated NGT. Results suggest that NGT calculated from widely used noble gas interpretive models do reflect measured WTT, supporting the use of dissolved noble gases to deduce recharge temperatures. Samples having dissolved gas concentrations below the equilibrium concentration with respect to atmospheric pressure were attributed to denitrification induced gas stripping in the saturated zone. Modeling indicated that minor degassing (<10% [Delta]Ne) may cause underestimation of groundwater recharge temperature by up to 2 °C. In another study a large dissolved noble gas data set (905 samples) from California was analyzed. Noble gas modeling using the same interpretive models indicates that multiple models may fit measured data within measurement uncertainty, suggesting that goodness-of-fit is not a robust indicator of model appropriateness. A unique aspect of this study was the high Ne and excess air concentrations associated with surficial artificial recharge facilities. A final study examined whether climatic/hydrologic changes occurring over glacial-interglacial time periods could impact the accuracy of NGT used in paleoclimate studies. Numerical modeling experiments estimated WTT sensitivity to changes in: 1) precipitation amount, 2) water table depth, and 3) air temperature. Precipitation and water table depth had a minor impact on WTT (~0.2 °C). In contrast, the impact of air temperature changes on WTT was more pronounced. Results suggest that air temperatures inferred from NGT data may underestimate actual air temperature change since the last glacial maximum by ~1 °C at sites having seasonal snowcover. These results suggest despite uncertainty in the exact physical processes controlling gas dissolution during groundwater recharge, NGT do reflect WTT. However, inferring paleo-air temperatures from NGT are subject to error, especially locations with seasonal snowcover.Earth and Planetary Science
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Optimal electrification planning in Sub-Saharan African countries
No full textAccess to reliable, sustainable, and affordable electricity services is essential for quality of life and economic development. However, ~53% of the population in Sub-Saharan Africa (SSA) live without access to electricity. Due to its rapid population growth and accelerated urbanization, Africa is a key driver of global energy demand growth. However, to meet the United Nations Sustainable Development Goal 7, which aims to achieve 100% electricity access by 2030, the region is faced with dual challenges of providing access to the 600 million people who currently lack electricity access while reaching the millions born every year in areas without access to electricity. A variety of local and national studies have been undertaken in recent years to provide feasible electrification solutions. This study first investigates the historical evolution and the current situation of electricity supply and demand, in order to reveal the links between electrification and socio-economic factors as well as energy resources exploration. Next, utilizing an open-source Spatial Electrification Tool (OnSSET), this study seeks the least cost electrification options for SSA countries, including grid-connection, mini-grid, and stand-alone systems, and analyzed the sensitivity of the results to projected population, energy targets, grid generation costs, diesel prices, and solar costs, etc. The results show that electrification rates vary spatially across SSA. Large electrification gaps exist between urban and rural areas in SSA, with 78% of the urban population and 27% of the rural population in SSA having electricity access in 2018. Electrification increased substantially in SSA from 25% in 2000 to 47% in 2018. East African countries, such as Ethiopia and Kenya, were leading the increase. The OnSSET model results suggest that, in urban areas with most of the population and close to transmission lines, grid extension is usually the least cost option, while stand-alone or mini-grid options are more economical in rural areas with less population and electricity demand. Detailed analysis of Angola and Senegal using the OnSSET model shows that for a certain level of access, the projected population connected to the grid ranges from ~70% in Angola to ~90% in Senegal by 2030. Considering a scenario with emission costs and renewable subsidies, with higher grid generation costs and lower solar cost, mini-grid solar or stand-alone solar options are favorable for more areas than grid extensionEnergy and Earth Resource
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Energy and water production trends in the Powder River Basin
No full textEnergy extraction and water are intrinsically linked. Quantifying this relationship is critical to develop effective management strategies that minimize adverse environmental impacts and potentially reduce production costs. The objective of this study was to assess the spatiotemporal variability in water use and water production through hydrocarbon extraction from conventional and unconventional reservoirs using data from the Powder River Basin in Wyoming as a case study. Field level and detailed well-by-well analyses were conducted to quantify the spatiotemporal variability of oil and gas volumes and the corresponding co-produced water from conventional oil reservoirs and coal bed methane (CBM) reservoirs, and additional water used for hydraulic fracturing in unconventional shale reservoirs. Results show that conventional oil and CBM gas production has markedly declined along with produced water. The water demands of unconventional oil and gas development in the last decade have increased with increasing unconventional oil production, however water use per unit of energy produced has increased. Produced water from unconventional oil wells does not meet hydraulic fracturing water demands. CBM wells in proximity to new unconventional well development may be a source of water needing minimal treatment for growing hydraulic fracturing water demands.Energy and Earth Resource
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Cost of desalinating brackish groundwater using stochastic estimates of groundwater storage volumes and salinity
No full textStrategic water planning in Texas is an important way to ensure Texans have enough water. With increasing climate extremes (droughts and floods) and climate change, new drought resistant supplies, such as brackish groundwater desalination, will become more important in the overall water portfolio in Texas. Current brackish groundwater studies produced by the state provide deterministic estimates of brackish groundwater storage volumes and groundwater salinity estimates. These estimates have high uncertainties; however, these uncertainties are not quantified or communicated. In this thesis two stochastic workflows were developed to reevaluate results of a deterministic brackish groundwater study: Monte Carlo simulation to produce stochastic storage estimates and ensemble learning to produce stochastic groundwater salinity estimates. These workflows were tested against the results of deterministic estimates, showing that the stochastic P50 storage estimate was about two times greater than the deterministic storage estimate when a lithologically appropriate specific yield distribution was sampled. The stochastic analysis also revealed that the aquifer storage estimates are highly uncertain due to a lack of measured data in the brackish aquifers. In reprocessing data from the original deterministic analysis, uncertainty in salinity estimates was found to increase with increasing salinity, which is expected due to the limited number of brackish and saline water quality samples in the public record. Finally, the stochastic estimates of storage and salinity were used to assess the cost of desalinating groundwater from a San Antonio Water System project in the 2022 State Water Plan. Results show that brackish groundwater salinity uncertainties had a greater effect on the cost of desalinated groundwater than the uncertainties in the storage volume estimates. Overall, by developing stochastic workflows and estimates, stakeholders can target specific data to acquire to reduce uncertainties for specific projects. The additional context provided by uncertainty analysis could greatly benefit stakeholdersEnergy and Earth Resource
Use of flow modeling to assess sustainability of groundwater resources in the North China Plain
No full textThe North China Plain (NCP) is one of the global hotspots of groundwater depletion. Currently, our understanding is limited on spatiotemporal variability in depletion and approaches toward more sustainable groundwater development in this region. This study was intended to simulate spatiotemporal variability in groundwater depletion across the entire NCP and explore approaches to reduce future depletion. Simulated predevelopment groundwater recharge (similar to 13 km(3)/yr) primarily discharged as base flow to rivers and evapotranspiration. Initial groundwater storage was estimated to be 1500 km(3) of drainable storage in shallow aquifers and 40 km(3) of compressive storage in deep aquifers. Simulated groundwater depletion from 1960s to 2008 averaged similar to 4 km(3)/yr. Cumulative depletion was 50 km(3) (similar to 20% of pumpage) in the piedmont district, 103 km(3) (similar to 20%) in the central plain, and 5 km(3) (12%) in the coastal plain. However, depletion varied with time: similar to 2.5 km(3)/yr in the 1970s, similar to 4.0 in the 1980s, similar to 2.0 in 1990-1996; similar to 7.0 in 1997-2001, and similar to 4.0 in 2002-2008. Recharge also varied spatially, averaging similar to 120 mm/yr and concentrated in the piedmont district (200-350 mm/yr) while lower in the central and coastal plains (50-100 mm/yr). Simulation of several alternatives, including managed aquifer recharge, increased water use efficiency, brackish water use, and interbasin water transfer, indicated that the combination of these strategies could be used to recover groundwater storage by 50 km(3) over a 15-year period. This study provides valuable insights for developing more sustainable groundwater management options for the NCP; the methods are useful for managing other depleted aquifers. Citation: Cao, G., C. Zheng, B. R. Scanlon, J. Liu, and W. Li (2013), Use of flow modeling to assess sustainability of groundwater resources in the North China Plain, Water Resour. Res., 49, doi:10.1029/2012WR011899.Environmental SciencesLimnologyWater ResourcesSCI(E)EI23ARTICLE1159-1754
Author Correction: Global water resources and the role of groundwater in a resilient water future
No full textIn the version of this article originally published, reference 9 was incorrectly cited in the last sentence of the second paragraph under ‘Introduction’ and in the first sentence of the second paragraph under the ‘Water scarcity’ subsection. Scanlon et al. (Environ. Res. Lett. https://doi.org/ 10.1088/1748-9326/ac3bfc, 2022) was incorrectly cited in the last sentence under ‘Drivers of water-resource variability’ but is now replaced with reference 38, and Figure 3 was wrongly stated to be adapted from reference 19 instead of reference 36. Reference 40 was mistakenly cited in the last sentence of the second paragraph under the ‘Increasing water access and supplies’ subsection, and reference 37 was inadvertently duplicated in the reference list. References 28 (now reading ‘Winter, T. C., Harvey, J. W., Franke, O. L. and Alley, W. M. Ground Water and Surface Water: A Single Resource. Circular 1139 (United States Geological Survey, 1998)’) and 94 (now reading ‘Scanlon, B. R., Reedy, R. C., Faunt, C. C., Pool, D. and Uhlman, K. Enhancing drought resilience with conjunctive use and managed aquifer recharge in California and Arizona. Environ. Res. Lett. 11, 035013 (2016)’) initially referred to incorrect sources. Lastly, the name of author Hannes Müller Schmied was incorrectly spelled Hannes Mueller Schmied, and an affiliation for him was missing: Senckenberg Leibniz Biodiversity and Climate Research Centre (SBiK-F), Frankfurt am Main, Germany. The errors have been corrected in the HTML and PDF versions of the article
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