Hydrometeorological analysis of flooding events in San Antonio, Texas

Flash flooding is the second leading cause of weather-related deaths in the United States. Texas is the state with most flood/flash flood deaths. San Antonio, the 7th largest city in the nation, is located in one of the most flash-flood prone regions in North America and has experienced a number of flooding events in the last decade (2002, 2004, and 2007). South Central Texas is particularly vulnerable to floods due to: (1) proximity to a moist air source (the Gulf of Mexico); (2) the Balcones Escarpment, which concentrates rainfall runoff; (3) a tendency for synoptic scale features to become cut-off and stall over the area; and (4) decaying tropical cyclones stalling over the area. Research into the benefits and potential applications of a physically-based, distributed hydrological model is being encouraged by increases in the availability of distributed watershed data and advances in computing power. This study used the Gridded Surface Subsurface Hydrological Model (GSSHA) to examine the hydrologic response of Leon Creek, Salado Creek, and Upper San Antonio River basins located in San Antonio, Texas to four major floods. The main source of precipitation input to the hydrologic model was the NEXt-generation RADar (NEXRAD) Multi-sensor Precipitation Estimator. Simulated discharges of flooding events produced by GSSHA model compared very well with the observed discharges.