Precipitation Erosivity Index Estimates in Cold Climates

ABSTRACT VARIATIONS in precipitation in mountainous regions increase the difficulty of estimating precipitation based parameters. Estimates of the USLE erosivity index (EI) are further complicated by snowfall in these and other cold climate areas. This report describes some of the variations in EI relationships observed at the Reynolds Creek Experimental Watershed in southwestern Idaho. Snowfall accounted for up to 71% of EI based on annual precipitation. Therefore, only summer EI values are considered valid for establishing the erosivity index. Summer EI values increased 28 to 59% when all storms were considered rather than only storms over 13 mm in volume..