Using a Three-Dimensional Hydrogeologic Framework to Investigate Potential Sources of Water Springs in the Death Valley Regional Groundwater Flow System

Abstract:

The Death Valley regional groundwater flow system encompasses a proposed site for a high-level nuclear waste repository of the United States of America, the Nevada National Security Site (NNSS), where nuclear weapons were tested, and National Park and BLM properties, and provides water for local communities. The model was constructed using a three-dimensional hydrogeologic framework and has been used as a resource planning mechanism by the many stakeholders involved, including four United States (U.S) federal agencies (U.S. Department of Energy, National Park Service, Bureau of Land Management, and U.S. Fish and Wildlife Service) and local counties, towns, and residents. One of the issues in recent model development is simulation of insufficient water to regional discharge areas which form springs in valleys near the center of the system. Given what seems to be likely rock characteristics and geometries at depth, insufficient water is simulated to reach the discharge areas. This “surprise” thus challenges preconceived notions about the system. Here we use the hydrogeologic model to hypothesize alternatives able to produce the observed flow and use the groundwater simulation to test the hypotheses with other available data. Results suggest that the transmissivity measurements need to be used carefully because wells in this system are never fully penetrating, that multiple alternatives are able to produce the springflow, and that one most likely alternative cannot be identified given available data. Consequences of the alternatives are discussed.