Developing a Radar-Based Flood Alert System for Sugar Land, Texas

Abstract

In recent years, there have been an increasing number of watersheds that relied on weather radars to provide accurate precipitation information for flood warning purposes. The major impetus for using a radar-based flood warning system is the increased flood warning lead time because of its wider spatial and temporal coverage when compared with rain and stream gauges alone. This paper presents a framework for a radar-based flood alert system (FAS) for the Oyster Creek Watershed to aid the City of Sugar Land in flood forecasting. Precipitation from two actual storm events in 2009 and 2010 were processed in the hydrologic model Hydrologic Engineering Center–hydrologic modeling system (HEC-HMS) to obtain storm hydrographs. After model calibration, the simulated peak flows were then inputted into the hydraulic model, Hydrologic Engineering Center river analysis system (HEC-RAS), to produce water surface elevations. The study includes two flood warning features of Sugar Land’s FAS: the flood plain map library (FPML) and the flood warning indicator (FWI). The FPML has the capability of portraying inundation levels in real time by displaying predelineated floodplain maps that best represent the current condition during storm events, whereas FWI could serve as a first line of defense by delineating specific areas with potential flooding problems within a watershed by using calibrated radar rainfall data. Both features aim to help city officials and emergency personnel plan for flood monitoring, evacuation planning, and traffic routing.