Evaluating micrometeorological estimates of groundwater discharge from Great Basin desert playas

Ground Water
By: , and 

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Abstract

Groundwater availability studies in the arid southwestern United States traditionally have assumed that groundwater discharge by evapotranspiration (ETg) from desert playas is a significant component of the groundwater budget. However, desert playa ETg rates are poorly constrained by Bowen Ratio energy budget (BREB) and eddy-covariance (EC) micrometeorological measurement approaches. Best attempts by previous studies to constrain ETg from desert playas have resulted in ETg rates that are within the measurement error of micrometeorological approaches. This study uses numerical models to further constrain desert playa ETg rates that are within the measurement error of BREB and EC approaches, and to evaluate the effect of hydraulic properties and salinity-based groundwater-density contrasts on desert playa ETg rates. Numerical models simulated ETg rates from desert playas in Death Valley, California and Dixie Valley, Nevada. Results indicate that actual ETg rates from desert playas are significantly below the uncertainty thresholds of BREB- and EC-based micrometeorological measurements. Discharge from desert playas likely contributes less than 2 percent of total groundwater discharge from Dixie and Death Valleys, which suggests discharge from desert playas also is negligible in other basins. Simulation results also show that ETg from desert playas primarily is limited by differences in hydraulic properties between alluvial fan and playa sediments and, to a lesser extent, by salinity-based groundwater density contrasts.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Evaluating micrometeorological estimates of groundwater discharge from Great Basin desert playas
Series title Ground Water
DOI 10.1111/gwat.12647
Volume 56
Issue 6
Year Published 2018
Language English
Publisher Wiley
Contributing office(s) Nevada Water Science Center
Description 12 p.
First page 909
Last page 920
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