Z-10 Countywide Floodplain Mapping Update

Z-10 Countywide Floodplain Mapping Update

Recent Action

May 11, 2021 – Harris County Commissioners Court approved an agreement to increase funds by $1,047,000 for engineering and related consulting services in support of this project.

October 13, 2020 – Harris County Commissioners Court approved $250,000 for engineering services and project management quality control services in support of this project.

May 19, 2020 – Harris County Commissioners Court approved updates to project details in the 2018 Bond Program List. Update changes project title and description of benefits to mention web-based flood-education tool.

project description

The Harris County Flood Control District and the Federal Emergency Management Agency (FEMA) are partnering on a flood hazard assessment project that will use the latest available 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 better understanding of flood risks throughout Harris County, including previously unmapped overland and non-riverine flooding.

Project Milestones

February 12, 2019 - Harris County Commissioners Court awarded contracts for floodplain mapping and related engineering services in support of this project.) 

January 29, 2019 - Harris County Commissioners Court approved a $2.5 million contract with an engineering firm for engineering, project management and control, and quality control services in support of this project

Project Name Project ID Current State Budget Funded Spent
Modeling, Assessment,
and Awareness Project
Z100-00-00-P025 Feasibility $ 15.5M
$ 14.5M $ 2.2M

Learn More about MAAPnext

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. This assessment will incorporate the National Oceanic and Atmospheric Administration’s (NOAA) recently released Atlas 14 results which included increased estimates to the total precipitation in standard return period events such as the “100-year”. 

Learn more about ATLAS 14

Other new data and information that will be utilized include 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.


Since its inception in 1937, the Harris County Flood Control District has continually worked to better understand flood risk throughout the county. This project represents a transformative step in the management and regulation of Harris County’s floodplains. Recent advancements in hydrologic and hydraulic modeling software and methodologies will allow HCFCD to identify and evaluate flood risks to a greater degree of accuracy and detail than was previously possible.

Figure 1. MAAPnext Watersheds - Phase 1 & 2

These advancements will allow HCFCD to understand and map flooding related to bayous, creeks and other natural drainage patterns. Additionally, flood risk due to rainfall run-off draining through streets and neighborhoods on the way to the bayous will also be assessed. The resulting data will produce a variety of flood mapping products that will allow area residents and business owners the opportunity to better understand flooding risks to support their actions and decisions in the future. 

The Harris County Modeling, Assessment and Awareness Project (MAAPnext) will develop the next generation of flood mapping. Along with new Flood Insurance Rate Maps (FIRMs), new tools will be developed for communicating the results of this project. Changes are on the way for Harris County flood maps, and we are ready to bring the region’s flood resistance and resilience to the next level.

(Click on graphic to expand)