Preliminary Investigation to Elucidate Volcanic Aquifer Characteristics and Potential Climate Change Impacts

The Fall River Springs system, located in northeastern California and part of the Northwest Volcanic Aquifer Province, is a valuable water resource for the state's agriculture and hydropower industries and is also of ecological significance. While efforts have been made to define the aquifer system and examine regional climatic changes, this project aims to further determine aquifer properties and characteristics that can be incorporated into a predictive model, creating a valuable tool for water resource management. A MODFLOW model is manually calibrated using observed spring discharge rates to determine the bulk hydraulic conductivity. This groundwater flow model is coupled with MT3DMS, a heat transport model, to determine the bulk thermal conductivity. Measurements of observed spring discharge temperature and recharge temperature, which are obtained from noble gas sampling, are used to constrain the heat model. These estimates and measurements serve to expand the basis of knowledge and supplement recent work on the spring system. Additionally, the recharge temperature data is compared to similar noble gas samples that were take 20 years prior. Differences in recharge and discharge temperatures between the two events provides understanding to climatic changes over time and insight to possible future changes.