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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

A pathway of global food supply adaptation in a world with increasingly constrained groundwater

Many of the world’s major freshwater aquifers are being exploited unsustainably, with some projected to approach environmentally unsafe drawdown limits within the 21st century. Given that aquifer depletion tends to occur in important crop producing regions, the prospect of running dry poses a significant threat to global food security. Here we use the Global Change Assessment Model (GCAM) to explore the response of land use and agriculture sectors to severe constraints on global water resources. We simulate a scenario in which a number of important groundwater aquifers become depleted beyond environmental or economically viable drawdown limits within the 21st century. Results are then benchmarked against scenario that neglects constraints on water extractions. We find that groundwater depletion and associated water price increases drive two distinct responses in the agriculture sector: an expansion of rain fed agriculture, and a shift in irrigated crop production toward regions with cheaper water resources. Losses in crop production are most pronounced in water stressed regions where groundwater is being depleted unsustainably to meet irrigation demands—namely northwest India, Pakistan, the Middle East, western United States, Mexico, and Central Asia. While these results highlight substantial risks for the affected regional agricultural economies, we show that modest changes in irrigation and location of crop growth could ensure global food demands are met despite severe water constraints.

Turner, Sean WD↗
DOE OSTI2013

Y-12 Groundwater Protection Program Extent Of The Primary Groundwater Contaminants At The Y-12 National Security Complex

This report presents data summary tables and maps used to define and illustrate the approximate lateral extent of groundwater contamination at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee. The data tables and maps address the primary (i.e., most widespread and mobile) organic, inorganic, and radiological contaminants in the groundwater. The sampling locations, calculated contaminant concentrations, plume boundary values, and paired map format used to define, quantify, delineate, and illustrate the approximate extent of the primary organic, inorganic, and radiological contaminants in groundwater at Y-12 are described.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Results of Temporary Shutdown Testing and Groundwater Pump-Testing at Agra, Kansas, February-September 2016 and march 2017, and Assessment of Groundwater and Contaminant Migration

In 2005, the Commodity Credit Corporation/U.S. Department of Agriculture (CCC/USDA) conducted a comprehensive investigation of potential contaminant source areas on, and in the vicinity of, the former CCC/USDA grain storage facility in Agra, Kansas (Argonne 2006). The data collected during this investigation identified three primary source areas for carbon tetrachloride contamination. One source is located on the former CCC/USDA property, and the other two (western and eastern) sources are located on adjacent property owned by Pro-Ag Marketing. The soil source located at the western end of the Pro-Ag property has been identified as the sole source of carbon tetrachloride contamination to the groundwater in this portion of the Agra site, and is not associated with any grain storage activities on the former CCC/USDA property. In 2008-2009, to address the carbon tetrachloride contamination detected on its former property, the CCC/USDA initiated source area cleanup as an interim measure (IM). The cleanup employs five large-diameter boreholes (LDBs) that were excavated by auger drilling. The purposes of these borings were to (1) physically remove soils impacted by carbon tetrachloride from the most contaminated area for treatment by onsite land farming and (2) provide locations for the installation of coupled soil vapor extraction (SVE) and air sparging (AS) wells to facilitate in-situ treatment of the carbon tetrachloride in the soils and underlying groundwater. With the approval of the KDHE, operation of the SVE/AS systems began in May 2009, and has generally continued with minimal interruption since that time. Land farming operations to treat contaminated soil excavated from the LDBs were successfully completed in October 2010.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Effects of groundwater pumping on ground surface temperature: A regional modeling study in the North China Plain

Over-exploitation of groundwater (GW) in the North China Plain (NCP) since the 1960s has many environmental consequences. However, understanding of the dominant mechanisms remains limited, particularly at regional scale. In this study, the coupled ParFlow.CLM model representing subsurface and land-surface processes and their interactions was applied in the NCP at high spatio-temporal resolutions. The model was validated using the water and energy fluxes reported in previous studies and from the JRA-55 reanalysis. Numerical experiments were designed to examine the relative impacts of GW pumping and irrigation on the ground surface temperature (GST). Results show significant effects of GW pumping on GST in the NCP. Generally, the subsurface acts as a buffer to temporal variations in heat fluxes at the land-surface, but long-term pumping can gradually weaken this buffer, resulting in increases in the spatio-temporal variability of GST, as exemplified by hotter summers and colder winters. Considering that changes of water table depth (WTD) can significantly affect land surface heat fluxes when WTD ranges roughly between 0.01–10 m, the 0.5 m/year increase of WTD simulated by the model due to pumping can continue to increase the average WTD and hence, disturb GST, for about 20 years from the pre-pumping WTD in the NCP, before the WTD exceeds 10 m. The variations of GST are expected to be faster initially and gradually slow down due to the nonlinear behaviors of GST with WTD. The findings from this study in the NCP may also have implications for other regions with GW depletion.

Yang, Chen↗
DOE OSTI2015

Baseline groundwater model update for p-area groundwater operable unit, NBN

This report documents the development of a numerical groundwater flow and transport model of the hydrogeologic system of the P-Area Reactor Groundwater Operable Unit at the Savannah River Site (SRS) (Figure 1-1). The P-Area model provides a tool to aid in understanding the hydrologic and geochemical processes that control the development and migration of the current tritium, tetrachloroethene (PCE), and trichloroethene (TCE) plumes in this region.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Independent Review of Groundwater Remediation Strategy for Hexavalent Chromium and RDX Groundwater Plumes at Los Alamos National Laboratory (Rev. 1)

Site operations at the Los Alamos National Laboratory (LANL) resulted in the release of oxidized chromium, Cr(VI), into Sandia Canyon from cooling tower effluent from 1956 until 1972. The chromium traveled with the surface water approximately 3 miles downstream before migrating below ground surface. Chromium concentrations exceed 50 μg/L in the upper portion of the aquifer. Another LANL groundwater plume of concern is associated with RDX (Royal Demolition Explosives, 1,3,5-trinitro-1,3,5-triazine). Between 1951 and 1996, RDX was released to the mesa-top facilities' process water outfall, adjacent and underlying soils, and alluvial sediments, along with surface water in Cañon de Valle. Between 2000 and 2010, two remedial actions were deployed, removing much of the near-surface RDX, however, recharge due to precipitation has transported RDX into the perched-intermediate zone and into the regional aquifer. The report documents an independent technical review by scientists from the Department of Energy (DOE) Network of National Laboratories for Environmental Management and Stewardship (NNLEMS) to provide recommendations for potential near term actions to address and optimize remediation for both the Cr(VI) and RDX plumes. The proposed near-term remedial actions include design of pump and treat systems for Cr(VI) and monitoring and study for natural attenuation for RDX. The review assesses existing data, conceptual and numerical modeling, and it recommends a technical integration process to support identifying and implementing strategic, effective and efficient remedies. The DOE Environmental Management Los Alamos Field Office (EM-LA) and their cleanup contractor Newport News Nuclear-BWTX, LLC Los Alamos (N3B) provided the information required for the review. Interviews were also conducted with regulators to obtain the full spectrum of technical, regulatory and scientific perspectives. The independent review team was impressed by the capabilities, experiences, innovativeness, and insightfulness of the technical representatives from both the regulator, the New Mexico Environment Department (NMED) and N3B. Incorporation of vadose zone flow pathways in the conceptual site model (CSM) and configuring the numerical modeling for the site was generally state-of-the-practice (or better). This could be considered state-of-the-art by addressing uncertainties related to spatial extent of hydraulic windows. The reviews from the regulators were thorough and often provided useful concepts for consideration and future/study resolutions. The overarching consensus recommendation of independent review team is that the LANL groundwater plumes should be addressed in context of the emerging "management of complex sites" paradigm.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2001

In-Situ Chemical Reduction and Oxidation of VOCs in Groundwater: Groundwater Treatability Studies

This paper presents NASA Marshall Space Flight Center's treatability studies for volatile organic compounds in groundwater. In-Situ groundwater treatment technologies include: 1) Chemical Reduction(Ferox); 2) Chemical Oxidation (Fenton Reagents, Permanganate, and Persulfate); and 3) Thermal (Dynamic Underground Stripping, Six-Phase Heating). This paper is presented in viewgraph form.

Keith, Amy↗
DOE OSTI2015

The long road to groundwater RODs on the ORR: development of a regional groundwater model - 15632

This paper describes the first year of planning and development for the Oak Ridge Reservation (ORR) regional groundwater flow model (ORGFM). The first stage involved the creation of a groundwater model Technical Advisory Group (TAG), made up of local and national industry experts to support the model development. As a first step in the model development process, a smaller-scale model (a Test Case Model) is being developed to test the modeling tools and approach being considered for the regional model. The Test Case Model is allowing the team to identify and develop work-flow processes on a small scale prior to developing the large, regional-scale model. The modeling team currently is testing the combined use of EarthVision{sup R} and MODFLOW-USG (a modular finite-difference flow model using un-structured grids) to develop the regional-scale model. It is anticipated that the ORGFM will be completed by 2016. This paper presents the progress of the ORGFM model development. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Is there a geomorphic expression of interbasin groundwater flow in watersheds? Interactions between interbasin groundwater flow, springs, streams, and geomorphology.

Interbasin groundwater flow (IGF) can play a significant role in the generation and geochemical evolution of streamflow. However, it is exceedingly difficult to identify IGF, and to determine the location and quantity of water that is exchanged between watersheds. How does IGF affect landscape/watershed geomorphic evolution? Can geomorphic metrics be used to identify the presence of IGF? We examine these questions in two adjacent sedimentary watersheds in northern New Mexico using a combination of geomorphic/landscape metrics, springflow residence times, and spatial geochemical patterns. IGF is expressed geomorphically in the landscape placement of springs, and flow direction and shape of stream channels. Springs emerge preferentially on one side of stream valleys where landscape incision has intercepted IGF flowpaths. Stream channels grow toward the IGF source and show little bifurcation. In addition, radiocarbon residence times of springs decrease and the geochemical composition of springs changes as the connection to IGF is lost.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Potential for Small Unmanned Aircraft Systems Applications for Identifying Groundwater-Surface Water Exchange in a Meandering River Reach: sUAS in Groundwater-Surface Water Study

The exchange of groundwater and surface water (GW-SW), including dissolved constituents and energy, represents a critical yet challenging characterization problem for hydrogeologists and stream ecologists. Here we describe the use of a suite of high spatial resolution remote sensing techniques, collected using a small unmanned aircraft system (sUAS), to provide novel and complementary data to analyze GW-SW exchange. sUAS provided centimeter-scale resolution topography and water surface elevations, which are often drivers of exchange along the river corridor. Additionally, sUAS-based vegetation imagery, vegetation-top elevation, and normalized difference vegetation index mapping indicated GW-SW exchange patterns that are difficult to characterize from the land surface and may not be resolved from coarser satellite-based imagery. We combined these data with estimates of sediment hydraulic conductivity to provide a direct estimate of GW “shortcutting” through meander necks, which was corroborated by temperature data at the riverbed interface.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Groundwater Contamination, Subsurface Processes, and Remediation Methods: Overview of the Special Issue of Water on Groundwater Contamination and Remediation

This special issue of Water brings together ten studies on groundwater contamination and remediation. Common themes include practical techniques for plume identification and delineation, the central role of subsurface processes, the pervasiveness of non-Fickian transport, and the importance of bacterial communities in the broader context of biogeochemistry.

Mays, David↗