The Changing Character of the California Sierra Nevada as a Natural Reservoir

Abstract

The mountains of the Western United States provide a vital natural service through the storage and release of mountain snowpack, lessening impacts of seasonal aridity and satiating summer water demand. However, climate change continues to undermine these important processes. To understand how snowpack may change in the headwaters of California's major reservoirs, the North American Coordinated Regional Climate Downscaling Experiment is analyzed to assess peak water volume, peak timing, accumulation rate, melt rate, and snow season length across both latitudinal and elevational gradients. Under a high‐emissions scenario, end‐of‐century peak snowpack timing occurs 4 weeks earlier and peak water volume is 79.3% lower. The largest reductions are above Shasta, Oroville, and Folsom and between 0‐ and 2,000‐m elevations. Regional climate model and global forcing data set choice is important in determining historical snowpack character, yet by end century all models show a significant and similar decline in mountain snowpack.

The Future of Sediment Transport and Streamflow Under a Changing Climate and the Implications for Long‐Term Resilience of the San Francisco Bay‐Delta

“…In California, snow is the primary source of surface water storage, and the April 1st snowpack measurement is a vital metric of the potential water resources available through the dry summer months. In our model domain, which is below the major reservoirs, modeled April 1st snow water equivalent (SWE) in the Sacramento River basin decreased dramatically across all future scenarios by end-of-century ( Figure 3) and is consistent with other studies assessing changes in snowpack in the Sierra Nevada (Gergel et al, 2017;Rhoades et al, 2018;Thorne et al, 2015). Compared to the historical baseline for each scenario, monthly April 1st SWE by end-of-century decreased from −86% to −100% for RCP 8.5 scenarios.…”

Can Convection‐Permitting Modeling Provide Decent Precipitation for Offline High‐Resolution Snowpack Simulations Over Mountains?

“…For instance, in the western United States (WUS) mountainous areas, snowpack accounts for about 70% of the total runoff and supplies water demands for millions of people (Li et al, ; Mote et al, ). However, the WUS snowpack has experienced widespread declines in the past decades (Mote et al, ; Mote et al, ; Pederson et al, ) and is projected to continue decreasing under a future warming climate (e.g., Cayan et al, ; Rasmussen et al, ; Godsey et al, ; Li et al, ; Berg & Hall, ; Gergel et al, ; Musselman et al, ; Huning & AghaKouchak, ; Rhoades, Ullrich, & Zarzycki, , Rhoades, Jones, & Ullrich, ; Marshall et al, ; Sun et al, ). Therefore, it is imperative to accurately simulate snowpack evolution in order to support weather and hydrological forecasts, climate modeling and projection, and water resource management, especially over mountainous regions.…”

Domestic well vulnerability to drought duration and unsustainable groundwater management in California’s Central Valley

“…Climate change compounds the impact of water management decision-making. Warming will increase the frequency and duration of drought in California and other parts of the world [36,37,35,34,68], and if left unchecked, groundwater withdrawal will likely intensify as surface water becomes more scarce, as it has in the past [21]. As we demonstrate in this study, groundwater replacement of lost surface water during extended drought intensifies well failure due to already low groundwater levels.…”

“…Like many other semi-arid, agriculturally intensive regions worldwide, in the decades to come, California will grapple with the impacts of climate change and policy on its overdrafted aquifers. By the end of the 21st century, California's snowpack is projected to decline by as much as 79.3% [34], and drought frequency in the southern CV may increase by upwards of 100% [35]. It is in this increasingly drier and warmer climate [36,37] characterized by more frequent, more spatially extensive heat waves and extended droughts [38,39], that California will implement a statewide policy of sustainable groundwater management [40].…”