NEON Intermountain Region Observatory Network (IRON)

Basin and Range, Steppe and Land Transition (BAR SALT)

Great Basin Carbonate and Alluvial Aquifer System (GBCAAS)

The following information regarding this study comes from the USGS - Utah Water Science Center website.

Purpose: The objective of the USGS Water Availability Program is to assess water availability in the Nation's major aquifer systems. The Great Basin Carbonate and Alluvial Aquifer System (GBCAAS) is part of this federally funded program. Specific objectives of this study include quantifying current ground-water resources, evaluating how those resources have changed over time, and developing tools to assess system responses to stresses from future human uses and climate variability.

Description of Study Area: The GBCAAS study covers an area of more than 100,000 mi2 encompassing most of the Great Basin regional auifer system. The area is characterized by numerous arid to semi-arid basins with unconsolidated alluvial aquifers separated by mountain ranges often comprised of carbonate aquifers. Population is concentrated within 100 miles of Salt lake City and in the Las Vegas area and is growing rapidly. The area includes two national parks and numerous national wildlife refuges.

Approach: This study will compile and interpret pertinent information related to the region's geology and hydrology to develop a conceptual understanding of water movement within the system and then use the knowledge to construct a numerical model for bette understanding the current system response to natural and human stresses. This tool will also be used to forecast how the system might respond to future climate variability and water use.

Timeline: The first year of this four-year (FY2007-FY2010) study focused on compiling hydrogeologic information and analyzing a previous REgional Aquifer Systems Analysis (RASA) numerical ground-water flow model for guidance in prioritizing additional data needs. During the second year, water budget components will be evaluated and a generalized hydrogeologic framework model will be developed. These will be incorporated into a new steady-state ground-water flow model. A transient ground-water flow model will be developed during the third year. Future projection simulations will be conducted during the fourth year and all water budget information will be summarized and interpreted in the context of both current and future ground-water availability.

Products: USGS reports will describe the geology, conceptual understanding of the hydrology, numerical ground-water models, and regional ground-water availability. A scientific journal article on the potential effects of climate variability and increased development on ground-water availability is also planned. In addition, all GIS data will be archived.

For more information on this project, please visit the GBCAAS website, or contact Victor Heilweil or Lynette Brooks.