Flooding from rain-on-snow events in the Sierra Nevada

Abstract

The most damaging floods in rivers of the Sierra Nevada of California have occurred during warm storms when rain fell in snow covered catchments. These large floods have inundated communities and farms in California's prime agricultural region. Forecasting of runoff from rain-on-snow events has been difficult for managers of dams and power plants within the Sierra Nevada and for downstream flood control agencies because of uncertainties about runoff production at high altitudes and snowmelt contributions at low altitudes. The high potential for flood generation from rain-on-snow events is related to their large contributing area, intensity and duration of rainfall, opportunity for snowmelt contributions, and the timing of water release from the snowpack.