Cypress Creek Floodplain Revision


Harris County Flood Control District


Service: Floodplain Management

Cypress Creek Floodplain Revision

Harris County

The 1% probability flood event elevation on the downstream side of a major road crossing of Cypress Creek was noted to be several feet lower than the hydraulic model based on field observations of two floods four years apart. As a result, Walter P Moore was asked to investigate, update, and recalibrate the hydrologic and hydraulic models to reflect conditions in the watershed as of the time of the Tropical Storm Allison Recovery Project (TSARP) and to incorporate more detailed information about the watershed. The study also provided supporting information for remapping as well as submittal and coordination with FEMA. The effort included field investigation of critical variables, recalibration of the models to three historical flood events, and reanalysis of the 10%-, 2%-, 1%-, and 0.2%-probability flood events, and the floodway for Cypress Creek. An innovative approach was taken in the methodology utilized for this study. A technical defense of methods was used on the project before a federally-appointed Scientific Resolution Panel. The panel decided unanimously in favor of the methodology used in this study.