Nevada Water Science Center

Evaluating Groundwater Discharge Rates, Nye County

Numerous studies completed by USGS have developed estimates of groundwater discharge in Amargosa Desert. Areas outside the influence of major springs and seeps, characterized by xerophytic vegetation, were assumed to contribute only minimally to groundwater discharge. Nye County representatives have expressed concerns that a substantial amount of groundwater discharge does occur in areas dominated by xerophytic vegetation where the depth to water is less than 50 feet. Nye County contends that 27,500 acre feet of groundwater discharge may have been overlooked in previous studies.

Research Plan

Groundwater discharge rates will be quantified using a combination of micrometeorological, plant, unsaturated zone, and groundwater measurements. Two instrumented sites established for this study will be located along a groundwater-well transect where depth to water increases from less than 10 feet to 50 feet and vegetation is xerophytic. A third site located at the USGS Amargosa Desert Research Site will serve as a control site. All three instrumented sites will be maintained for 3 continuous years to provide a longer-term data set that will capture seasonal and annual changes in climate, and be more representative of average-annual climatic conditions.

Background

Numerous studies completed by the U.S. Geological Survey (USGS) have developed estimates of groundwater discharge in Amargosa Desert (Czarnecki and Stannard, 1997; Laczniak and others, 1999; Laczniak and others, 2001). Groundwater discharge was estimated by measuring groundwater discharge rates in long-established groundwater discharge areas. In southern Nevada, traditional groundwater discharge areas are typified by various species of phreatophytic vegetation situated near major springs and seeps, and discharging playas. Areas outside the influence of major springs and seeps, characterized by xerophytic vegetation, were assumed to contribute only minimally to groundwater discharge.

Nye County representatives have expressed concerns that a substantial amount of groundwater discharge does occur in areas dominated by xerophytic vegetation where the depth to water is less than 50 feet. These areas, as mapped by Nye County, consist of 46,000 acres where the depth to groundwater is less than 10 feet, and 45,000 acres where depth to water is between 10 and 50 feet. The groundwater discharge rate estimated by Nye County for each respective area is 0.5 and 0.1 ft/yr. Based on these estimates, Nye County contends that 27,500 acre feet of groundwater discharge may have been overlooked in previous studies.

USGS has been estimating water budgets in Nevada since the 1940’s. The Office of the State Engineer historically has relied upon USGS water-budget estimates as the basis for determining perennial yield, and to allocate available water resources. If the hypothesis advanced by Nye County is confirmed, a substantial revision of the water budget and perennial yield would likely result.

USGS scientists measuring a sample from the study area

Quick Facts

 

Location: Nye County, southern Nevada

Start Date: 2010

End Date: 2014

Cooperator: Nye County

Contact Information

 

Mike Moreo

USGS Nevada Water Science Center

160 N. Stephanie St.

Henderson, NV 89074

phone: (702) 564-4625

Email: mtmoreo@usgs.gov

 

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page Last Modified: May 2, 2012