Validation and Sensitivity of a Convective Precipitation Model for Mountainous Areas

Abstract

A convective precipitation model for use in regions of complex terrain has been developed and applied to the Gunnison River Basin in southwestern Colorado. Spring snowfall in the Rocky Mountain region often has a significant convective component which orographic precipitation models are unable to simulate. Additionally, summertime precipitation is predominately convective in this area and is responsible for a large portion of summer streamflow variability. Streamflow typically increases by 50 to 100 percent of baseflow for moderate rainfall events for periods of up to one week. Larger precipitation episodes can produce peak discharges that exceed the spring snowmelt peaks. Convective precipitation also is important for plant growth, minimum streamflows and fire hazard conditions. In addition, an accurate assessment of the response of hydrologic systems to climate variability and change requires an accurate estimate of convective precipitation in mountainous areas. The convective model accurately reproduced the trend and amount of observed precipitation for the test period August 14-20, 1989. The convective model has applicability for downscaling large-scale model precipitation to smaller scales for use in water quality and quantity assessments.