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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5078

Evapotranspiration Rate Measurements of Vegetation Typical of Ground-Water Discharge Areas in the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah, September 2005–August 2006

Prepared in cooperation with the Bureau of Land Management

By Michael T. Moreo, Randell J. Laczniak, and David I. Stannard

Abstract

Evapotranspiration was measured at six eddy-correlation sites for a 1-year period between September 1, 2005, and August 31, 2006. Five sites were in phreatophytic shrubland dominated by greasewood, and one site was in a grassland meadow. The measured annual evapotranspiration ranged from 10.02 to 12.77 inches at the shrubland sites and 26.94 inches at the grassland site. Evapotranspiration rates correlated to measured vegetation densities and to satellite-derived vegetation indexes. Evapotranspiration rates were greater at sites with denser vegetation. The primary water source supporting evapotranspiration was water derived from local precipitation at the shrubland sites, and ground water at the grassland site. Measured precipitation, ranging from 6.21 to 11.41 inches, was within 20 percent of the computed long-term annual mean. The amount of ground water consumed by phreatophytes depends primarily on local precipitation and vegetation density. The ground-water contribution to local evapotranspiration ranged from 6 to 38 percent of total evapotranspiration at the shrubland sites, and 70 percent of total evapotranspiration at the grassland site. Average depth to water ranged from 7.2 to 32.4 feet below land surface at the shrubland sites, and 3.9 feet at the grassland site. Water levels declined throughout the growing season and recovered during the non-growing season. Diurnal water-level fluctuations associated with evapotranspiration were evident at some sites but not at others.

Contents

Foreword
Abstract
Introduction
Evapotranspiration
Limitations of Methodology
Summary
Acknowledgments
References Cited
Appendix A. Evapotranspiration data for the Basin and Range carbonate-rock aquifer system study area, Nevada and Utah, September 2005-August 2006

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Download Appendix A (Excel, 7 MB)

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Send questions or comments about this report to the author, M.T. Moreo, (702) 564-4625.

For more information about USGS activities in Nevada, visit the USGS Nevada Science Center home page.