Comparing Physically-Based Hydrologic Model Streamflow Simulations for a Small Mixed-Land Use Catchment Utilizing S- and X-Band Dual-Polarization Radars and Terrestrial Based Tipping Buckets

Quantitative precipitation estimations (QPE) are one of the most fundamental properties hydrometeorologists consider when conducting hydrologic simulations. Rainfall provides the largest amount of water input to a watershed for the majority of watersheds in arid regions, which is mandatory for closing off the water-mass balance equation necessary for simulations. Over the past few decades, multiple studies have been conducted to calculate rainfall rates estimated by weather radars through algorithms consisting of combinations reflectivity (Z), differential reflectivity (ZDR), and specific differential phase shift (KDP). Furthermore, recent studies have been conducted to test the performance of radar rain rates for streamflow prediction with conflicting results in the literature as to the performance of radar rainfall rates compared to the standard, broadly-spaced rain gauge data being implemented. The purpose of this study was to test the performance of over 100 radar rain rate algorithms from two distant S-band Weather Surveillance Radar 1988-Doppler (WSR-88D) radars in conjunction with a nearby X-band as precipitation input to a small mixed-use watershed with a physically-based hydrologic model, Vflo® in estimating streamflow. The results were compared to forcing areal-averaged tipping-bucket data to the catchment to determine whether significant (CI = 0.05) differences between the input methods existed. Results indicate that utilization of weather radars provide more accurate streamflow estimates, but require more calibration than standard rain gauges.