Delineation of spring capture zones in southern Great Basin, USA based on modeling results and geochemical data

Abstract

The protection zones or capture zones of springs in desert environments can be hard to identify, but they are critical to spring protection. Most springs fed by regional aquifers are susceptible to contamination and groundwater development. The U.S. Environmental Protection Agency has established hydrogeologic mapping methods to delineate protection zones for springs. However, it is often difficult to determine a regional aquifer system's flow pattern with this technique alone, and the use of these methods is not conducive to efficient groundwater management. Particle tracking analysis using a well-conceptualized and calibrated numerical model for the three-dimensional groundwater flow domain feeding a given group of springs can help facilitate the identification of spring capture zone boundaries. Building upon this basis, a multifaceted approach was developed to define clear boundaries of the capture zones for the springs in the Furnace Creek, Ash Meadows, and the Muddy River areas in the southern Great Basin, USA. Capture zones were first delineated from inverse particle tracking and Hydrologic Unit 12 watersheds. Afterwards, they were adjusted based on water budgets, geology, and hydrologically significant faults. Finally, a geochemical analysis of the groundwater chemistry and isotopic data was conducted to verify the extent of each spring capture zone. This multifaceted approach adds confidence to the new delineations.