Quantifying the groundwater/surface-water interactions under the changing climatic conditions in a mountainous watershed

Abstract:

More and more attentions have been paid on depletion of groundwater in the past years in the Central Valley, California, USA, where groundwater plays a critical role in agriculture. However, surface water has received less attentions than groundwater, especially in the headwater basins serving as important water source areas and aquatic habitats. The Sacramento River is one of the most important natural water sources in the Central Valley, California, USA. Its headwater basins which include the Sacramento Head River, the McCloud River and the Pit Rivers originating from Mountain Shasta and Cascade Range may significantly affect surface water and groundwater discharge of the downstream watersheds. Due to complex surface-water and groundwater interactions in the mountains as well as the limited hydrogeologic and climatic data, the hydrological responses to climate change in headwater catchments are usually difficult to predict. The potential feedbacks of surface water and groundwater and their interactions on a changing climate in mountainous catchments are largely unknown. The objective of this study is to analyze the responses of the headwater basins of Sacramento River to climate change as well as quantify the interactions of surface-water and groundwater in the mountainous blocks to promote the comprehensive utilization of surface- and groundwater resources of the downstream Sacramento River. An integrated hydrological model, GSFLOW coupled with climate projections from CMIP6 is used. The research outputs will be helpful for enhancing the understanding of the key factors controlling the flow of headwater systems and improving the vulnerability of downstream catchment to both human activities and climate change for sustainable groundwater management.