Effects Of Climate Change And Fire On Sediment In The Southern Rockies Ecoregion

Forests in the Southern Rockies Ecoregion are critical sources of water to many states in the western and central USA. The quality of that water, particularly with regard to sediment, is dependent on weather and land cover, which are both likely to change in response to changes in climate and related wildfires. This study used the Revised Universal Soil Loss Equation (RUSLE) to calculate the sediment produced on forests for the timeframes 2010 to 2040 and 2041 to 2070 at 90 m resolution. A new method to calculate rainfall erosivity was devised to incorporate the effects of climate change from statistically downscaled GCM data for IPCC SRES scenarios A2 and B1. Soil erodibility, topography, and management practices were held constant over time, but projected changes in land cover were incorporated from a previous study that estimated the effects of climate change on wildfire. We calculated 90 iterations of RUSLE for each climate scenario and timeframe for downscaled weather projections from two global climate models, ECHAM5 and HadCM3. We estimate potential increases of up to 67% in mean sediment delivered when climate change and land cover changes due to wildfire were included. Effects on sediment were greatest using the ECHAM5 climate model for the B1 scenario. Results of this study provide land and water resource managers estimates of the location, amount, and trend of changes in sediment delivered to streams under future conditions.