Implications of surface runoff recharge in semi-arid regions on groundwater sustainability

Omar Mohammad Al-Qudah, University of Texas at El Paso

Abstract

Amargosa Desert, Nevada regional groundwater studies show that the surface runoff infiltration occurring in the arroyos following runoff producing storms, and this infiltration is considered to be a major source of groundwater recharge. Groundwater infiltration through alluvium was investigated in the Amargosa Desert using borehole drill cuttings, groundwater chemistry, and applying a novel method for collecting runoff water. The sampling process included sediment, precipitation, and runoff water. In total, 176 runoff, 182 sediment, and 45 precipitation samples were collected between January, 2009 and January, 2011.Water chemistry, chloride concentrations, and stable isotopes of water collected from specially designed runoff samplers, placed in the main ephemeral arroyo and its tributaries in the Amargosa Desert, closely match the chemistry of underlying groundwater where a plume of low chloride water underlies the arroyos until it connects with the Amargosa River. This evidence indicates that current and past infiltration of surface runoff (stormwater) is the primary source of the underlying groundwater plume. The results suggest that infiltration of surface runoff from large storm events in this region is a source of recharge more important that previously realized. Furthermore, the analyses of results indicate that the dominant processes and reactions responsible for the hydrochemical evolution in the Amargosa Desert water system are (1) evaporative concentration prior to infiltration, (2) carbonate equilibrium, (3) silicate weathering reactions, (4) limited mixing with saline water, (5) dissolution/precipitation of calcite, dolomite and fluorite, and (6) ion exchange. The results also indicate that the northern west face of Yucca Mountain groundwater is fresh water, Fortymile Wash groundwater is dilute, and the carbonate signature is shown in the Ash Meadows and Death Valley waters. Moreover, the results show three main groundwater signatures indicating groundwater evolution, potential flowpaths, and recharge areas. The flowpaths are the trace of the Amargosa River, the trace of Fortymile Wash, and its convergence with the Amargosa River. This appears to represent not just a groundwater flow path, but traces of surface runoff infiltration as well.^

Subject Area

Hydrology|Engineering, Chemical|Engineering, Environmental

Recommended Citation

Al-Qudah, Omar Mohammad, "Implications of surface runoff recharge in semi-arid regions on groundwater sustainability" (2011). ETD Collection for University of Texas, El Paso. AAI3469317.
http://digitalcommons.utep.edu/dissertations/AAI3469317

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