Summary

Description

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.