These data represent potential areas of ground-water discharge for selected hydrographic areas in eastern Nevada and western Utah. The data are based on phreatophyte boundaries published by the U.S. Geological Survey (USGS) and on unpublished boundaries mapped by the Southern Nevada Water Authority (SNWA). Selected basins also were mapped by the USGS during an aerial field reconnaissance. The largest phreatophyte extent from all the sources was typically selected as the final boundary where a basin was covered by multiple boundaries. Selected basins were field verified and modified to reflect the ground condition during the summer of 2005. This data set also includes subbasin boundaries identified by Sweetkind and others (2007) (See Source_Information). The table below lists the boundary sources for each valley and whether the data were ground verified. > Valley Sources Field > verified ------------------------------------------------------------------------------------------ >Little Smoky Nichols, 2000; Harrill, 1988 Yes >Newark Nichols, 2000; Harrill, 1988 Yes >Long Nichols, 2000; Harrill, 1988; SNWA Yes >Jakes Nichols, 2000; SNWA Yes >Butte Nichols, 2000; Harrill, 1988; SNWA Yes >Steptoe Nichols, 2000; Harrill, 1988; SNWA No >Tippett Nichols, 2000 No >Spring Nichols, 2000; Harrill, 1988; SNWA Yes >Snake Harrill, 1988; SNWA; Aerial No >Lake Harrill, 1988; SNWA; Aerial Yes >Cave SNWA; Aerial No >White River Harrill, 1988; SNWA; Aerial Yes

This data set consists of sub delineations of the hydrographic area (HA) boundaries and polygons drawn at 1:1,000,000 scale for the Great Basin supplemented by information from HA drawn at 1:750,000 scale where necessary. See the process steps for more information.

This data set contains polygons representing potential areas of groundwater discharge (PAGWD) for the upper Humboldt River Basin, northeastern Nevada.

This data set contains polygons representing potential areas of groundwater discharge (PAGWD) for the upper Humboldt River Basin, northeastern Nevada.

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 groundwater discharge area (GDA) in the DVFS. Vegetated areas within the GDA are composed of phreatophytic shrubs with smaller areas of grassland, marshland, xeric vegetation, bare soil, and agricultural lands where phreatophytic shrubs historically were present. Vegetated areas outside the GDA are primarily composed of xeric vegetation and bare soil although very sparse phreatophytic shrubs may be present on the outer margins of the boundary. The GDA was mapped in the summer of 2011 using field reconnaissance and supporting digital data. Additional supporting field information was gathered in fall of 2014.

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 groundwater discharge area (GDA) in the DVFS. Vegetated areas within the GDA are composed of phreatophytic shrubs with smaller areas of grassland, marshland, xeric vegetation, bare soil, and agricultural lands where phreatophytic shrubs historically were present. Vegetated areas outside the GDA are primarily composed of xeric vegetation and bare soil although very sparse phreatophytic shrubs may be present on the outer margins of the boundary. The GDA was mapped in the summer of 2011 using field reconnaissance and supporting digital data. Additional supporting field information was gathered in fall of 2014.

Accurate estimates of ground-water discharge are crucial in the development of a water budget for the Basin and Range Carbonate-rock Aquifer System (BARCAS) study area. One common method used throughout the southwest United States is to estimate ground-water discharge from evapotranspiration (ET). ET is a process by which water from the Earth's surface is transferred to the atmosphere. The volume of water lost to the atmosphere by ET can be computed as the product of the ET rate and the acreage of vegetation, open water, and moist soil through which ET occurs. The procedure used in the study, groups areas of similar vegetation, water, and soil conditions into different ET units and assigns an average annual ET rate to each unit. The data sets and the procedures used to delineate the ET-unit map are described in this metadata.

Accurate estimates of ground-water discharge are crucial in the development of a water budget for the Basin and Range Carbonate-rock Aquifer System (BARCAS) study area. One common method used throughout the southwest United States is to estimate ground-water discharge from evapotranspiration (ET). ET is a process by which water from the Earth's surface is transferred to the atmosphere. The volume of water lost to the atmosphere by ET can be computed as the product of the ET rate and the acreage of vegetation, open water, and moist soil through which ET occurs. The procedure used in the study, groups areas of similar vegetation, water, and soil conditions into different ET units and assigns an average annual ET rate to each unit. The data sets and the procedures used to delineate the ET-unit map are described in this metadata.

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. 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.