VALIDATION AND SENSITIVITY OF A CONVECTIVE PRECIPITATION MODEL FOR MOUNTAINOUS AREAS

A convective precipitation model for use in regions of complex terrain has been developed and applied to the Gunnison River Basin in southwe stern Colorado. Spring snowfall in the Rocky Mountain region often has a significant convective component which orographic precipitation mod els are unable to simulate. Additionally, summertime precipitation is predominately convective in this area and is responsible for a large p ortion of summer streamflow variability. Streamflow typically increase s by 50 to 100 percent of baseflow for moderate rainfall events for pe riods of up to one week. Larger precipitation episodes can produce pea k discharges that exceed the spring snowmelt peaks. Convective precipi tation also is important for plant growth, minimum streamflows and fir e hazard conditions. In addition, an accurate assessment of the respon se of hydrologic systems to climate variability and change requires an accurate estimate of convective precipitation in mountainous areas. T he convective model accurately reproduced the trend and amount of obse rved precipitation for the test period August 14-20, 1989. The convect ive model has applicability for downscaling large-scale model precipit ation to smaller scales for use in water quality and quantity assessme nts.