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.

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 the mean Enhanced Vegetation Index (EVI) of two Landsat 5 Thematic Mapper scenes from the summer of 2010 in the DVFS. The data were used to evaluate and estimate groundwater discharge by evapotranspiration by relating the mean of EVI calculated from July 24 and August 25, 2010 Landsat scenes to evapotranspiration measured at 4 eddy-covariance sites located in phreatophytic vegetation of varying types and densities in Kobeh Valley, Nevada. Evapotranspiration was extrapolated for all valleys in the study area using the relation developed for Kobeh valley.

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 the mean Enhanced Vegetation Index (EVI) of two Landsat 5 Thematic Mapper scenes from the summer of 2010 in the DVFS. The data were used to evaluate and estimate groundwater discharge by evapotranspiration by relating the mean of EVI calculated from July 24 and August 25, 2010 Landsat scenes to evapotranspiration measured at 4 eddy-covariance sites located in phreatophytic vegetation of varying types and densities in Kobeh Valley, Nevada. Evapotranspiration was extrapolated for all valleys in the study area using the relation developed for Kobeh valley.

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. ETg 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 were constrained by the groundwater discharge area (GDA) represented by this dataset. The GDA 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. The GDA was delineated during field reconnaissance of the study area.

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.

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 represent the extent and spatial distribution of irrigated acreage delineated from maximum Normalized Difference Vegetation Index (NDVI) derived from Landsat scenes in the Walker River Basin, California and Nevada, at five-year intervals from 1975-2010. The field boundaries in this data set are digitized from one-year composite maximum NDVI data derived from atmospherically corrected Landsat 2 Multispectral Scanner (MSS), Landsat 5 MSS, and Landsat 5 Thematic Mapper (TM) scenes. NDVI was calculated from the corrected reflectance data for each selected scene during the growing season (May through early October) and a single, composite image of maximum NDVI values was derived for each five-year interval. Selecting the maximum NDVI value removed low values associated with plant phenology, harvest cycles, and irrigation operations. Initial field boundaries were digitized from the 2010 National Agriculture Imagery Program (NAIP) data and boundary geometries were divided and shaped based on temporal changes in irrigation practices, crop rotations, and other changes identified in the Landsat-derived maximum NDVI data. Each polygon is attributed with an estimated irrigation status of irrigated or non-irrigated. Mapped fields were classified as irrigated during a growing season if more than 45-percent of a field had a maximum NDVI value greater than or equal to 0.4.

These data represent the extent and spatial distribution of irrigated acreage delineated from maximum Normalized Difference Vegetation Index (NDVI) derived from Landsat scenes in the Walker River Basin, California and Nevada, at five-year intervals from 1975-2010. The field boundaries in this data set are digitized from one-year composite maximum NDVI data derived from atmospherically corrected Landsat 2 Multispectral Scanner (MSS), Landsat 5 MSS, and Landsat 5 Thematic Mapper (TM) scenes. NDVI was calculated from the corrected reflectance data for each selected scene during the growing season (May through early October) and a single, composite image of maximum NDVI values was derived for each five-year interval. Selecting the maximum NDVI value removed low values associated with plant phenology, harvest cycles, and irrigation operations. Initial field boundaries were digitized from the 2010 National Agriculture Imagery Program (NAIP) data and boundary geometries were divided and shaped based on temporal changes in irrigation practices, crop rotations, and other changes identified in the Landsat-derived maximum NDVI data. Each polygon is attributed with an estimated irrigation status of irrigated or non-irrigated. Mapped fields were classified as irrigated during a growing season if more than 45-percent of a field had a maximum NDVI value greater than or equal to 0.4.

This dataset, created in support of USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Nevada, 2016-18, represents a Normalized Difference Vegetation Index calculated for vegetated areas in the Stump Spring groundwater discharge area (GDA) and Area of Critical Environmental Concern (ACEC). Vegetated areas within the GDA are composed of phreatophytic shrubs interspersed with xeric vegetation and bare soil. The GDA was delineated by visual interpretation of 1-meter National Agriculture Imagery Program (NAIP) aerial imagery acquired in May of 2015. The NDVI was calculated from a June 2017 WorldView 2 image resampled to 1-meter cell size and masked to remove bare ground areas identified from a supervised classification based on the same 2015 NAIP image used to define the GDA.

This dataset, created in support of USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Nevada, 2016-18, represents a Normalized Difference Vegetation Index calculated for vegetated areas in the Stump Spring groundwater discharge area (GDA) and Area of Critical Environmental Concern (ACEC). Vegetated areas within the GDA are composed of phreatophytic shrubs interspersed with xeric vegetation and bare soil. The GDA was delineated by visual interpretation of 1-meter National Agriculture Imagery Program (NAIP) aerial imagery acquired in May of 2015. The NDVI was calculated from a June 2017 WorldView 2 image resampled to 1-meter cell size and masked to remove bare ground areas identified from a supervised classification based on the same 2015 NAIP image used to define the GDA.