Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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Event-Based Streamflow Simulation using the TREX Distributed Model

Huiling Yuan, Jonathan J. Gourley, Paul J. Schultz, John A. McGinley, and Christopher J. Anderson

Short-range quantitative precipitation forecasts (QPF) not only provides useful weather information also adds value to river forecasts. This study is to investigate the usefulness of high-resolution QPF in simulating streamflow over the North Fork American River Basin in Northern California through a spatially distributed hydrologic model. Event-based streamflow simulation is conducted for selected heavy rainfall events using the Two-Dimensional Runoff Erosion and Export (TREX) model. During the Hydrometeorological Testbed (HMT)-West campaign, ensemble forecasts at 3-km resolution were implemented in the Northern California region, including four mesoscale model configurations based on the Weather Research and Forecasting (WRF) model. All models were diabatically initialized by the local analysis and prediction system (LAPS), which greatly reduces the "spin-up" problem for the 0-6-h QPF. The 0-6h ensemble-mean QPF and the 6-h quantitative precipitation estimate (QPE) are disaggregated to hourly rainfall at 150 x 150 m pixels as the input to the TREX model. The TREX parameters are calibrated for one heavy rainfall event using the QPF and QPE respectively and applied to the rest events for validation. Statistical scores are computed based on the time, peak, and volume of the simulated discharge compared to the USGS observations. For some events, the simulation results using the QPF show increased value versus the simulation using the QPE. The TREX model also shows deficiencies in simulating snowmelt events. A snowmelt model is recommended in future research and operation.