On CMORPH Rainfall for Streamflow Simulation in a Small, Hortonian Watershed

The objective is to assess the use of the Climate Prediction Center morphing method (CMORPH) (similar to 0.073 degrees latitude-longitude, 30 min resolution) rainfall product as input to the physics-based fully distributed Gridded Surface-Subsurface Hydrologic Analysis (GSSHA) model for streamflow simulation in the small (21.4 km(2)) Hortonian watershed of the Goodwin Creek experimental watershed located in northern Mississippi. Calibration is performed in two different ways: using rainfall data from a dense network of 30 gauges as input, and using CMORPH rainfall data as input. The study period covers 4 years, during which there were 24 events, each with peak flow rate higher than 0.5 m(3) s(-1). Streamflow simulations using CMORPH rainfall are compared against observed streamflows and streamflow simulations using rainfall from a dense rain gauge network. Results show that the CMORPH simulations captured all 24 events. The CMORPH simulations have comparable performance with gauge simulations, which is striking given the significant differences in the spatial scale between the rain gauge network and CMORPH. This study concludes that CMORPH rainfall products have potential value for streamflow simulation in such small watersheds. Overall, the performance of CMORPH-driven simulations increases when the model is calibrated with CMORPH data than when the model is calibrated with rain gauge data.