Harris County Floodplain Remapping

Harris County Floodplain Remapping

Harris County Floodplain Remapping

Harris County (which contains the City of Houston) has suffered numerous catastrophic floods over the years, and the public demands progress in terms of flood risk communication and flood damage reduction. This demand was evidenced on August 25, 2018, when Harris County voters overwhelmingly supported a $2.5 billion bond program. 

The public wants to rebuild sustainable communities. They need high-quality, detailed flood risk and hazard maps that are easily accessed and understood. Most importantly, they need to develop a better understanding of flood risks in order to make key life decisions such as when and where to buy a home, and the flood insurance premiums for that home (all Harris County residents are encouraged to buy flood insurance). In order to provide this vital information, the Harris County Flood Control District  and County leadership have determined that updated Flood Insurance Rate Maps are needed for Harris County, and the District has worked with the Federal Emergency Management Agency to develop a Map Activity Statement to guide the development of updated Risk Map products for all of Harris County’s 22 major watersheds. 

HDR has been selected to provide professional engineering, project management and control, and quality control services to support the HCFCD in delivering these important products for the citizens of Harris County. A highly qualified team of engineering firms and drainage professionals has been assembled to complete this effort, with HDR serving as the prime consultant with primary responsibility for project management, oversight, and quality control. In that role, our team, which includes Pape-Dawson Engineers, Inc., Walter P. Moore and Associates, Inc., Crouch Environmental Services, Inc., and Kleinschmidt, will oversee the efforts of other consultants selected by the HCFCD to perform floodplain modeling and mapping services. 

In addition, our team will be responsible for floodplain modeling and mapping services for selected watersheds. Hydraulic modeling will involve linked 1D/2D HEC-RAS models, with hydrograph inputs developed using HEC-HMS. A number of innovative approaches and techniques will be utilized in this study, including rain-on-grid analyses aimed at identifying flood risks that traditional floodplain studies do not take into account. Floodplain mapping products may include non-National Flood Insurance Program layers that contain information specific to Harris County and representative of the types of flooding experienced in this portion of the Gulf Coastal Plain.

The project will be completed in two phases. Phase I will involve studies of 11 watersheds located in the northern and western portions of Harris County. Phase II will involve studies of the remaining 11 watersheds located in the southern and eastern portions of the county. The project duration for modeling and mapping will be approximately three years, with an additional one to two years allocated for developing and perfecting the new floodplain maps.

Harris County Floodplain Remapping
Harris County Flood Control District

Harris County, TX
United States

Watershed area of about 2,270 square miles and about 1,150 miles of streams studied