6B.5

Hydrologic Evaluation of Radar Rainfall Retrievals for Urban Flood Forecasting

Baxter E. Vieux, University of Oklahoma, Norman, OK; and S. Bell, R. Nichols, and P. B. Bedient

Improved technology using radar and processing algorithms have the potential to improve flood warnings at specific locations in an urban environment. Quantitative precipitation estimates (QPE) derived from radar are useful in runoff simulation in operational flood forecasting, drainage design, and flood mitigation efforts. Radar data used in this analysis are derived from both S-band (NEXRAD) and X-band radars. Using radar QPE derived from the existing WSR-88D (KHGX) as input to a physics-based hydrologic model of Brays Bayou provides a baseline for comparison and guides design of future radar networks. Results indicate that radar resolution is a critical determinant for accurate hydrologic forecasting at the small basin scale. The Collaborative Adaptive Sensing of the Atmosphere, Engineering Research Center is deploying the Houston Testbed for testing network-based radar retrieval. The X-band radars operate within a network and are referred to as NETRAD. The testbed initially focuses a small urban basin called Harris Gully (~10-km ²), which is interior to Brays Bayou. A high-resolution distributed hydrologic model, Vflo^TM is setup using LiDAR digital terrain for use with NEXRAD archival radar data, and for evaluating NETRAD radar products in preparation for real-time operational use. Both the main stem of Brays Bayou and the Harris Gully tributary have caused flood damages in the Houston Museum district, Rice University campus, and the Texas Medical Center during past tropical storms, viz., Tropical Storm Allison in June of 2001.

Session 6B, Weather to Climate Scale Flood Forecasting
Thursday, 18 January 2007, 1:30 PM-4:45 PM, 211

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