Examining Hurricane Rainfall Patterns in the Upper Gulf of Mexico

In conjunction with the SSPEED Center, rainfall patterns and large rainfall events in the upper Gulf of Mexico are being studied in an effort to better understand how to protect the region from hurricane events. Given the large size of the watersheds flowing from the north and west, statistical methodologies, such as the PMP and PDDF, were employed to better design and predict the shape, pattern, size, and intensity of large rainfall events. Using HMR 52, as well as local hydrologic reports, the 24 hour PMP was created for the upper Gulf of Mexico. In addition, large historic storms, such as Hurricane Katrina, Hurricane Rita, and Hurricane Ike, were simulated over the Houston-Galveston region in a hydrologic/hydraulic model with the use of radar and rain gauge data. VfloTM, a distributed hydrologic model was used to model these storms. The region was first calibrated to USGS stream gauge data from Greens Bayou, and the modeled results accurately depict key features of observed hydrographs, including time to peak, discharge, and the double peak phenomenon. Results from the design storms in the region indicate that flows from the north are greater than flows from the west; however, the flows from the west peak days earlier than those from the north. These hydrograph results are being used to model a surge gate to protect the Houston Ship Channel from hurricanes.