With increasing population growth and land-use change, urban communities in the desert southwest are progressively looking to remote basins to supplement existing water supplies. Recent applications for groundwater appropriations from Dixie Valley, Nevada, a primarily undeveloped basin neighboring the Carson Desert to the east, have prompted a reevaluation of the quantity of naturally discharging groundwater. The objective of this study was to develop a new, independent estimate of groundwater discharge by evapotranspiration (ET) from Dixie Valley using a combination of eddy-covariance evapotranspiration measurements and multispectral satellite imagery. Mean annual groundwater ET (ETg) was estimated during October 2009-2011 at four eddy covariance sites. Two sites were located in phreatophytic shrubland dominated by greasewood and two were located on a playa. Estimates were scaled to the basin level by combining remotely sensed imagery with field reconnaissance and site-scale ETg estimates. Vegetation index and brightness temperature data were used to partition Dixie Valley into five discharging ET units, and scale actual and potential ETg to the basin level. ET units are spatially constrained by a groundwater discharge area which represents the area where discharge from evaporation by open water or bare soil and transpiration from phreatophytic plants exceeds the volume of water contributed by precipitation. Each ET unit represents a generalized grouping of vegetation and soil conditions that were used as the basis of estimation of total ETg. ET units were partitioned as: playa lake, playa, sparse shrubland, moderate-to-dense shrubland, and grassland.

These data were created as part of a hydrologic study to characterize groundwater budgets and water quality in the Diamond Valley Flow System (DVFS), central Nevada. This dataset represents evapotranspiration (ET) units derived from the mean Enhanced Vegetation Index (EVI) calculated from two Landsat 5 Thematic Mapper scenes from the summer of 2010. ET units were defined within the DVFS groundwater discharge area (GDA) to group areas characterized by similar phreatophytic vegetation type and cover and to extrapolate site-scale groundwater ET estimates across the study area. This dataset represents three ET units: shrubland, grassland, and playa. The shrubland unit is composed of low to high density phreatophytic shrubs and bare soil while the grassland ET unit is composed of grassland, meadow, and marshland vegetation assemblages. The ET units were developed using a combination of EVI and site scale discharge measurements. The data were used to evaluate and estimate groundwater discharge by evapotranspiration in the study area. ET unit delineations reflect general spatial changes on the landscape and are not intended to be exact delineations of plant communities or soil conditions.

This vector dataset consists of 2 polygon shapefiles representing the groundwater discharge areas (GDA) and evapotranspiration (ET) units for the Amargosa Wild and Scenic River and contributing areas. GDAs were delineated by visual interpretation and subdivided into ET units of moist soil, open water, and vegetated areas.

With increasing population growth and land-use change, urban communities in the desert southwest are progressively looking to remote basins to supplement existing water supplies. Recent applications for groundwater appropriations from Dixie Valley, Nevada, a primarily undeveloped basin neighboring the Carson Desert to the east, have prompted a reevaluation of the quantity of naturally discharging groundwater.The objective of this study was to develop a new, independent estimate of groundwater discharge by evapotranspiration (ET) from Dixie Valley using a combination of eddy-covariance evapotranspiration measurements and multispectral satellite imagery. Mean annual groundwater ET (ETg) was estimated during October 2009-2011 at four eddy covariance sites. Two sites were located in phreatophytic shrubland dominated by greasewood and two were located on a playa. Estimates were scaled to the basin level by combining remotely sensed imagery with field reconnaissance and site-scale ETg estimates.The Enhanced Vegetation Index (EVI) was calculated for 10 Landsat 5 Thematic mapper scenes and combined with brightness temperature in an effort to reduce confounding (high) EVI values resulting from forbes and cheat grass in sparsely vegetated areas, and biological soil crusts from bare soil to densely vegetated areas. The resulting EVI/TB images represented by this dataset were used to calculate ET units and scale actual and potential ETg to the basin level.

This data release contains geospatial data for the lower Walker River basin from the 2009 publication: Allander, K.A., Smith, J.L., and Johnson, M.J., 2009, Evapotranspiration from the lower Walker River basin, west-central Nevada, water years 2005-07: U.S. Geological Survey Scientific Investigations Report 2009-5079, https://doi.org/10.3133/sir20095079.

This data release contains geospatial data for the lower Walker River basin from the 2009 publication: Allander, K.A., Smith, J.L., and Johnson, M.J., 2009, Evapotranspiration from the lower Walker River basin, west-central Nevada, water years 2005-07: U.S. Geological Survey Scientific Investigations Report 2009-5079, https://doi.org/10.3133/sir20095079.

This data release contains geospatial data for the lower Walker River basin from the 2009 publication: Allander, K.A., Smith, J.L., and Johnson, M.J., 2009, Evapotranspiration from the lower Walker River basin, west-central Nevada, water years 2005–07: U.S. Geological Survey Scientific Investigations Report 2009-5079, https://doi.org/10.3133/sir20095079.

Abstract from SIR 2017-5079: This report documents methodology and results of a study to evaluate groundwater discharge by evapotranspiration (GWET) in sparsely vegetated areas of Amargosa Desert and improve understanding of hydrologic-continuum processes controlling groundwater discharge. Evapotranspiration and GWET rates were computed and characterized at three sites over 2 years using a combination of micrometeorological, unsaturated zone, and stable-isotope measurements. One site (Amargosa Flat Shallow [AFS]) was in a sparse and isolated area of saltgrass (Distichlis spicata) where the depth to groundwater was 3.8 meters (m). The second site (Amargosa Flat Deep [AFD]) was in a sparse cover of predominantly shadscale (Atriplex confertifolia) where the depth to groundwater was 5.3 m. The third site (Amargosa Desert Research Site [ADRS]), selected as a control site where GWET is assumed to be zero, was located in sparse vegetation dominated by creosote bush (Larrea tridentata) where the depth to groundwater was 110 m. Results indicated that capillary rise brought groundwater to within 0.9 m (at AFS) and 3 m (at AFD) of land surface, and that GWET rates were largely controlled by the slow but relatively persistent upward flow of water through the unsaturated zone in response to atmospheric-evaporative demands. Greater GWET at AFS (50 ± 20 millimeters per year [mm/yr]) than at AFD (16 ± 15 mm/yr) corresponded with its shallower depth to the capillary fringe and constantly higher soil-water content. The stable-isotope dataset for hydrogen (δ2H) and oxygen (δ18O) illustrated a broad range of plant-water-uptake scenarios. The AFS saltgrass and AFD shadscale responded to changing environmental conditions and their opportunistic water use included the time- and depth-variable uptake of unsaturated-zone water derived from a combination of groundwater and precipitation. These results can be used to estimate GWET in other areas of Amargosa Desert where hydrologic conditions are similar.

This vector data set represents the evapotranspiration (ET) station location points in the lower Walker River basin.

This vector data set represents the evapotranspiration (ET) station location points in the lower Walker River basin.