Using MPE and Rain Gauges Precipitation Products for Uniform Rainfall on The Upper Guadalupe River Basin of the Texas Hill Country in Physically Based Distributed Parameters Rainfall Surface Runoff Models

Introduction: The validating MPE product which mainly composed of NEXRAD product as a remote sensing product with the rain gauges precipitation product for uniform rainfall on the Upper Guadalupe River Basin in the Texas Hill Country has been studied in a very detailed study using a different statistical method such as probability of rain detection (POD) by Xianwei Wang et al. (2007). This product also has been used into different rainfall runoff model such as HEC HMS and GSSHA model (Gridded surface subsurface hydrological assessment) in the region. The validity of this product using physically based rainfall runoff distributed model is still remain a challenge in using the NEXRAD - MPE Stage III product in these applications putting into consideration the spatial and temporal distribution variability. To Study the rainfall distribution effect on surface runoff and infiltration to achieve the accurate surface water budget. GSSHA model is sensitive to rainfall (Ogden et al. Methodology: The study is used the MPE product as an input parameter in GSSHA model to produce the simulated discharge and then compared with the rain gauges data which used as an input parameter in a second model run. The two results were compared with the measured discharge to confirm the use MPE product in GSSHA. Data: The MPE data (4 km * 4 km) for the period of 11/1/2004 to 11/30/2004 is processed form its row binary format to match the GSSHA model format as well the rain gauges data. Other data was needed to be included in the model such as land use, soil parameters data, channel bathymetry and DEM, was also processed to match GSSHA format. Results: The results showed a significant match in comparison between measured and simulated outlet discharge since the rainfall data from MPE or rainfall data from gauges is effecting the spatial and temporal distribution of the surface runoff, infiltration and channel discharge. The spatial and temporal distributions of MPE and Rainfall from rain gauge data are also matched. On the other hand some calibrations were applied to some uncertain parameters within its' physical limits such as Green and Ampt soil parameters.