About MAAPnext

MAAPnext Project Overview

Funded by FEMA, 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?

MAAPnext will improve the understanding of the flood risk in Harris County so that the public, local communities, and emergency managers can make informed decisions to protect life and property.

The Harris County Flood Control District (Flood Control District) and the Federal Emergency Management Agency (FEMA) are partnering on a flood hazard assessment project that uses 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, FEMA and the Flood Control District will provide a better understanding of flood risks throughout Harris County, including previously unmapped urban flooding, which is flood risk due to rainfall run-off draining through streets and neighborhoods on the way to the bayous.

NEW DATA

Other new data and information that will be used include updated terrain data and improved hydrologic and hydraulic modeling technology and methods.

RESULTS THAT IMPACT FUTURE PLANNING

FEMA and the Flood Control District expect many changes to be reflected in the resulting flood risk maps. These changes will impact how future projects, new development, and their associated mitigation strategies are implemented.

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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.”

Interim Guidelines and Criteria for Atlas 14 Implementation

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WHAT DATA INFORMS MAAPNEXT?

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Impervious and Land Use Data Updated 2018

MAAPnext will use updated permeability data based on 2018 aerial imagery.

New 1D/2D Hydraulic Models

Up-to-date versions of the Hydrologic Modeling System and River Analysis System software products developed by the Hydrologic Engineering Center of the U.S. Army Corps Engineers now allows for feasible countywide 1D/2D analysis.

Topographic Data – LiDAR and Survey

Updated terrain data was obtained in 2018 and provides the foundation of hydraulics models and maps.

Public Outreach and Communication

If you have questions, concerns, or feedback related to MAAPnext, please visit the Get Involved. We look forward to working with you to deliver this significant project for our region and beyond!

Historical Storm Data and Atlas 14 Data

This assessment will incorporate updated rainfall depth, duration, and frequency data from the National Oceanic and Atmospheric Administration’s (NOAA) recently released Atlas 14, Volume 11 Precipitation-Frequency Atlas of the United States, Texas, and updated terrain data developed in 2018.

Completed flood damage reduction projects

In some cases, the Harris County Flood Control District may already be implementing a flood damage reduction strategy that will reduce flood risk for a given area. Data regarding completed flood damage reduction projects will be incorporated into MAAPnext.

WHY IS THIS PROJECT BEING DONE?

The MAAPnext project is being done to improve the understanding of the risk of flooding in Harris County so that the public, the Flood Control 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 will include new hydrologic and hydraulic models, floodplain mapping, and other flood risk products that were delivered to FEMA for review in the first quarter of 2022. The project will include the creation of new flood hazard communications tools by the Flood Control District and FEMA. FEMA will be releasing new preliminary Flood Insurance Rate Maps (FIRMs) when ready for public review.

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

MAAPnext was officially initiated in 2019 and is supported with funding from multiple FEMA grants and the 2018 Flood Control District Bond Program. The project will conclude with FEMA releasing new preliminary Flood Insurance Rate Maps (FIRMS) by the end of 2026 and the Flood Control District creating new flood hazard communications tools.

Grant 1 Watersheds

Grant 1 funded the hydrologic and hydraulic analysis of 11 of the County’s 22 watersheds. In early 2019, the Flood Control District received a grant from FEMA, which provided funding to start the county-wide study.

Grant 2 Watersheds

FEMA grant funding for the remaining 11 watersheds was received in late 2019, allowing the second phase of hydrologic and hydraulic analysis to begin.

Flood Insurance Rate Map Update Timeline

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 Flood Control District has continually worked to better understand and manage 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 FIRMs for all of Harris County in 2007.

FEDERAL EMERGENCY MANAGEMENT AGENCY (FEMA)

The Federal Emergency Management Agency (FEMA) is the federal agency responsible for leading the Nation's efforts to prepare for, protect and mitigate against, respond to, and recover from the impacts of natural disasters and man-made incidents or terrorist events. FEMA works to reduce disaster losses related to flooding by promoting initiatives, such as the development and adoption of national building or fire codes and standards, effective land use planning, increased use of disaster insurance (such as flood insurance), and provision of technical expertise on building techniques that minimize future losses. FEMA also administers the National Flood Insurance Program (NFIP) to reduce the financial impact of flooding disasters. Updated floodplain maps and flood risk information produced through MAAPnext will ultimately be finalized by FEMA.

FLOODPLAIN ADMINISTRATORS

In all, there are 35 floodplain administrators in the county. Throughout MAAPnext, the Flood Control District works 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. The Flood Control District is not a floodplain administrator.

HARRIS COUNTY RESIDENTS

The Flood Control District is committed to including Harris County residents throughout the implementation of MAAPnext by delivering 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 here.

Harris County MAAPNext