CALIFORNIA’S HYDROCLIMATIC VARIABILITY AND ITS INFLUENCE ON WATER SUPPLY THROUGH DROUGHT AND DELUGE

California has one of the largest economies in the world and provides 1/3 of the vegetables and 2/3 of the fruits and nuts produced in the United States. However, California’s precipitation variability continues to make headlines due to extreme wet and dry years. One of the biggest problems is the mismatch between when water is needed and when it falls, as most of the annual precipitation is received during the winter months but highest demand is during the summer. Further complicating the dynamic is that over the last couple of years there has been an annual swing from one extreme to the other, which has directly or indirectly caused droughts, wildfires, and floods resulting in billions of dollars in damage. Precipitation and streamflow data have shown an increasing trend in variability during the winter, which is mostly driven by wet extremes getting wetter in northern and southern California over the last 80 years. Moreover, this increasing 20^th century trend in hydroclimatic variability driven by wetter extremes seems to be unprecedented compared to the past 600 years as shown by tree-ring reconstructions. These trends drive our current work to investigate the past, present, and future of one of the most important watersheds in northern California for water supply—the upper Feather River watershed. This watershed drains about 8,300 square kilometers (km²) and provides access to water for 27 million people and 3,000 km² of farmland. Wildfires in 2020 and 2021 burned over 50% of the watershed. We quantify the burned watershed response to CMIP5 (Coupled Model Intercomparison Project Phase 5) monthly precipitation output from 2010–2100 using the Basin Characterization Model, a monthly water-balance model. We recognize the urgent need to gain a clearer understanding of the intricate connections between climate extremes, water resources, and the environment.