Z-10 County-wide Floodplain Mapping Update
The Harris County Flood Control District and the Federal Emergency Management Agency (FEMA) are partnering on a flood hazard assessment that will use the most up-to-date technology and data to produce the county’s most comprehensive and complete set of flood hazard maps and information.
Using new methodologies and technologies, the Flood Control District will provide a more complete understanding of flood risks throughout Harris County, including previously unmapped overland and non-riverine flooding. The effort will be completed in phases and will cover the county’s 22 major watersheds, all 34 local communities and unincorporated Harris County. The first phase will consist of 11 watersheds and begin in early 2019. The Flood Control District applied for and has received a grant from FEMA to provide funding for this phase. A second grant application for the remaining watersheds will be submitted, allowing the second phase to begin by the end of 2019, depending on when the second grant is awarded.
Project results, including new hydrologic and hydraulic models, floodplain mapping, and other flood risk products will be delivered to FEMA for review by the second quarter of 2021. The project will conclude with the Flood Control District creating new flood hazard communications tools and FEMA releasing new preliminary Flood Insurance Rate Maps (FIRMs) by the end of 2023.
The multi-year assessment will include new rainfall frequency data, updated terrain data, and improved hydrologic and hydraulic modeling technology and methods. The project will improve the understanding of the risk of flooding in Harris County so that the public, local communities and emergency managers can make informed decisions to protect life and property that may be at risk during flood events. The Flood Control District expects many changes to be reflected in the resulting flood risk maps that will impact how future projects, new development, and their associated mitigation strategies are implemented.