Modeling Runoff Genera on in a Small Snow-Dominated Mountainous Catchment

Snowmelt in mountainous areas is an important contributor to river water fl ows in the western United States. We developed a distributed model that calculates solar radia on, canopy energy balance, surface energy balance, snow pack dynamics, soil water fl ow, snow–soil–bedrock heat exchange, soil water freezing, and lateral surface and subsurface water fl ow. The model was applied to describe runoff genera on in a subcatchment of the Dry Creek Experimental Watershed near Boise, ID. Calibra on was achieved by op mizing the soil water fi eld capacity (a trigger for lateral subsurface fl ow), lateral saturated soil hydraulic conduc vity, and ver cal saturated hydraulic conduc vity of the bedrock. Valida on results show that the model can successfully calculate snow dynamics, soil water content, and soil temperature. Modeled streamfl ow for the valida on period was underes mated by 53%. The ming of the streamfl ow was captured reasonably well (modeling effi ciency was 0.48 for the valida on period). The model calcula ons suggest that 50 to 53% of the yearly incoming precipita on in the subcatchment is consumed by evapotranspira on. The model results further suggest that 34 to 36% of the incoming precipita on is transformed into deep percola on into the bedrock, while only 11 to 16% is transformed into streamfl ow.