This project represents a transformative step in the management and regulation of Harris County’s floodplains, further contributing to our county’s resilience.
New methodologies and technologies will provide a better understanding of flood risks throughout Harris County.
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.
WHAT ARE WE DOING?
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 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.
NEW METHODOLOGIES AND TECHNOLOGIES
Using new methodologies and technologies and the most granular data available, the Flood Control District will provide a better understanding of flood risks throughout Harris County, including previously unmapped urban flooding.
NEW DATA
Other new data and information that will be utilized include updated terrain data and improved hydrologic and hydraulic modeling technology and methods.
RESULTS THAT IMPACT FUTURE PLANNING
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.
ATLAS 14
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.”
The MAAPnext project is being done to improve the understanding of the risk of flooding in Harris County so that the public, the District, our communities, and emergency managers can make more informed decisions to protect life and property against flooding.
MAAPnext aims to improve Harris County's flood risk toolkit by:
Using the latest estimates of rainfall risk to update our Flood Insurance Rate Map
Studying and mapping additional miles of streams to update our Flood Insurance Rate Map
Developing additional maps that will more thoroughly communicate flood risk
PROJECT RESULTS
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.
Flood Insurance Rate Maps (FIRMS)
A FIRM displays the floodplains—more explicitly, special hazard areas and risk premium zones—as delineated by FEMA.
A FIRM will generally show:
Roads and map land marks
Flood zones
Base flood elevations
Floodplain boundaries
Water surface elevation change grids
Representations of the difference between the effective and revised 1% annual chance floodplain water surface elevations.
Flood depth grids
Representations of the modeled water surface elevation for various flood frequencies, primarily the 10%, 4%, 2%, 1% and 0.2% annual chance flood events.
Urban Flooding Map
Representation of flood risk due to rainfall run-off draining through streets and neighborhood on the way to bayous.
Percent annual chance grids
Provide a better understanding of the relative probability of being flooded for any given location within the mapped floodplain.
Percent 30-year chance grids
Representation of the percent chance of a discrete location experiencing flooding at least one time during a 30-year period.
Water surface elevation grids
Representations of the modeled water surface elevation for various flood frequencies, primarily the 10%, 4%, 2%, 1% and 0.2% annual chance flood events.
These flood risk products will allow Harris County to understand flood risk by visualizing flood depths, flood water surface elevations, interpolated annual chance risk, and percent 30-year chance flood hazards.
MAAPNEXT PROJECT SCHEDULE
The MAAPnext effort will be completed in phases and will cover all of the county’s 22 major watersheds, all 34 local communities and unincorporated Harris County.
Phase 1 Watersheds
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.
Phase 2 Watersheds
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.
MAAPNEXT PROJECT PARTNERS
MAAPnext is a collaboration that brings together national resources and local knowledge.
HARRIS COUNTY FLOOD CONTROL DISTRICT (HCFCD)
Since its inception in 1937, the Harris County Flood Control District has continually worked to better understand flood risk throughout the county. The Flood Control District's ongoing partnership with FEMA has led to MAAPnext, as well as the previous Tropical Storm Allison Recovery Project (TSARP), which resulted in new FEMA Flood Insurance Rate Maps for all of Harris County in 2007.
FEDERAL EMERGENCY MANAGEMENT AGENCY (FEMA)
The Flood Control District is participating in partnership with FEMA to deliver this effort, providing local matching funds and authorizing negotiations with expert engineering firms to support delivery of MAAPnext.
FLOODPLAIN ADMINISTRATORS
Throughout MAAPnext, the Flood Control District will work closely with the floodplain administrators within Harris County, all of whom have their own drainage design criteria. In unincorporated areas of Harris County, the County Engineer's office is the floodplain administrator. In all, there are 35 floodplain administrators in the county. (The Harris County Flood Control District is not one of them.)
HARRIS COUNTY RESIDENTS
The Flood Control District is committed to including Harris County residents throughout implementation of MAAPnext by implementing a consistent, continuous education program for the Harris County population to more easily understand and more clearly communicate about flood risks. If you would like to participate in the program, please contact us.
ABOUT MAAPNEXT
