THE DEATH VALLEY REGIONAL GROUNDWATER FLOW SYSTEM MODEL: SOUND SCIENCE

Determining whether the development and application of a regional groundwater flow model is worth the effort is difficult to quantify. The Death Valley regional groundwater flow system (DVRFS) is an area of approximately about 80,000 sq. km. that includes Yucca Mountain, Death Valley National Park, and the Nevada National Security Site (formerly the Nevada Test Site). The cost to develop the numerical model over 10 years was significant at more than $20 million from the Yucca Mountain Project, other Department of Energy programs, and other Federal agencies. In contrast, the benefits derived from developing and applying the DVRFS model are numerous. Scientists, cooperators, and stakeholders have gained a better understanding of the hydrologic relationships between the Paleozoic carbonate rocks and volcanic rocks, the likely flow paths for potential contaminants, and the possible impacts from natural and anthropogenic stresses such as climate change or pumping. Additionally, a great deal of data have been collected and hydrologic information on the flow system has been documented, including: (1) geologic and geophysical data and synthesizing this information into a 3D hydrogeologic framework model; (2) water budget components such as evapotranspiration, spring flow, water levels, groundwater pumping, and recharge; (3) system boundary fluxes; (4) hydraulic properties; (5) numerical code enhancements, including several packages for MODFLOW; (6) a calibrated flow model; and (7) information products such as datasets, and reports.

The development of the DVRFS model was beneficial. In addition to the model, the supporting studies documented hydrologic conditions in a nationally significant, arid region were affected minimally by anthropogenic activities. The studies described techniques and produced peer reviewed data that have been and will continue to be applied to similar areas outside of DVRFS.