Enhanced Radar-Based Flood Alert System and Floodplain Map Library

Flood warning systems have become increasingly important for highly urbanized areas like the Texas Medical Center (TMC) area in the Brays Bayou Watershed of southwest Houston due to the watershed's flood characteristics and the difficulty of employing flood control measures under limited spatial conditions. An existing flood alert system (FAS2) has been developed incorporating adjusted higher-resolution next generation radar (NEXRAD) rainfall data, geographic information system, and hydrologic models to provide advanced real-time warning to TMC via the internet, e-mail, and cell phone during severe storms. This enhanced system utilizes 5-min NEXRAD rainfall data as input to hydrologic models and produces outputs at control points of choice in the form of hydrograph computation as a storm passes over the watershed. In this way, lead time for emergency managers to react is increased over other manual type systems. The FAS2 system has been tested with excellent results during three rainfall events in 2006 since the flood alert system was upgraded in 2004. Because of its forecasting capability, FAS2 is being used as a platform to develop a new hydraulic prediction tool-FloodPlain Map Library (FPML) in order to provide real-time visualized data on flood inundation levels as rainfall occurs. The linkage of NEXRAD rainfall data with improved hydrologic and hydraulic models improves FAS2 with a major step forward in prediction capability and visualization. This paper provides details of the FAS2 system, evaluates the performance of the existing FAS2 system during the 2006 season, and provides the theoretical basis for the development of the FPML system with some preliminary results.