The Current and Future State of Snowpack in the Colorado Rocky Mountains

Water available for ecological and human needs in the western U.S. is largely derived from seasonal mountain snow that accumulates during the winter and spring, and melts during the spring and summer each year. Mountain snowpacks are experiencing climate-induced changes that include earlier snowmelt, declining snow covered area, and decreases in the fraction of precipitation falling as snow. These changes pose a major risk to future water availability in the western U.S., yet there is currently uncertainty about future snow dynamics given its complex interactions with the atmosphere, land cover, and terrain. In addition, the hydrology of ungauged basins is often poorly understood, due to a lack of meteorological and hydrometric measurements. When such basins are important runoff contributors, this absence of knowledge often yields poor runoff forecast estimates. Thus, this study simulates snowpack conditions and streamflow in ungauged basins using the SnowModel, a spatially-distributed physically-based snow evolution modeling system, driven by high-resolution regional climate model output to more accurately predict future changes in snowpack across the Colorado Rocky Mountains. We will show specific results related to (1) each simulated component of the water balance, (2) the distribution of snow and variability in snowpack properties, and (3) future anticipated changes in forest structure and their influences on snow water resources.