A Distributed Modeling System for Short-Term to Seasonal Ensemble Streamflow Forecasting in Snowmelt-Dominated Basins

This paper describes a distributed modeling system for short-term to seasonal streamflow forecasts with the ability to utilize daily remotely-sensed snow cover products and real-time streamflow and meteorology measurements. Canopy interception, snow accumulation and melt, and simplified soil water movement are simulated in each computational unit. The model is run at a daily time-step with surface runoff and subsurface flow aggregated at the basin scale. This approach allows the model to be updated with spatial snow cover and measured streamflow using an Ensemble Kalman-based data assimilation strategy that accounts for uncertainty in weather forecasts, model parameters, and observations used for updating. Model inflow forecasts for the Dworshak Reservoir in north-central Idaho are compared to observations and to April-July volumetric forecasts issued by the Natural Resource Conservation Service (NRCS) for Water Years 2000 - 2006. October 1 and March 1 volumetric forecasts are superior to those issued by the NRCS. The ensemble spread brackets the observed April-July volumetric inflows in all years except for the October 1, 2006 forecast.