HR: 0830h
AN: H21C-03    [Abstracts]
TI: Improved Flood Prediction in an Urban Watershed Using a Physically-Based Modeling Approach
AU: * Adams, R
EM: russella@engin.umass.edu
AF: University of Massachusetts, Department of Civil and Environmental Engineering 18 Marston Hall, Amherst, MA 01003-5205 United States
AU: Rees, P L
EM: rees@ecs.umass.edu
AF: University of Massachusetts, Department of Civil and Environmental Engineering 18 Marston Hall, Amherst, MA 01003-5205 United States
AU: Bedient, P B
EM: bedient@rice.edu
AF: Rice University, Department of Civil and Environmental Engineering, Houston, TX United States
AU: Vieux, B E
EM: bvieux@ou.edu
AF: University of Oklahoma, School of Civil Engineering and Environmental Science, Norman, OK United States
AB: A modeling strategy has been developed to improve the real-time forecasting of medium to large magnitude floods in an urban watershed, Brays Bayou (260 km²), in Houston, TX. Severe flooding of downstream areas of the watershed around the Texas Medical Center (TMC) has been an increasing problem over the past few decades, particularly during Tropical Storm (TS) Allison in June 2001. Since late 2003, the physically-based distributed hydraulic model, Vflo^TM, using a relatively coarse (122m) finite element grid, has been run alongside HEC-1 as an ensemble for real-time flood forecasting at strategic locations on the main channel. The models are driven by local NEXRAD L2 radar data. Both Vflo^TM and HEC-1 are incorporated into the Flood Alert System 2 (FAS2), which was developed for the TMC through Rice University. Both FAS2 and its predecessor FAS have done well in predicting the magnitude and timing of flooding. However, during TS Allison, stormwater in Harris Gully (20.7 km²) overflowed, resulting in millions of dollars in damages. In addition, the City of Houston is currently installing new stormwater conduits which will change the pattern of flow from Harris Gully to the larger Brays Bayou. The SWMM model has been applied to this subcatchment; however its long run-time precludes its use for real-time forecasting. It is intended to develop a more detailed Vflo^TM model of the smaller Harris Gully subcatchment to explore several questions, including: 1) in order to improve real-time forecasts further for the TMC, highly accurate quantitative precipitation estimate data at the spatial resolution relevant for urban areas (e.g. a city block) and a distributed hydrologic model of the same spatial resolution are necessary, 2) even in heavily urbanized areas, dependence on flood properties on a basin scale derives from the space-time scaling properties of rainfall, 3) urbanization, particularly in small (less than 100 km²) basins, alters traditional scaling theories of flood response. The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) aims to provide a new archetype of precipitation product data for the TMC region of downtown Houston. Data available through CASA will enable the research questions to be addressed. In addition, improvement in real-time flood forecasting attributable to the development of new weather radar precipitation estimation (QPE) techniques will be assessed.
DE: 1821 Floods
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2005 Joint Assembly