MAAPnext Background & Innovation

MAAPnext Project Overview

Funded through a combination of FEMA grants and local funding provided by Harris County, 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.

MAAPnext (Modeling, Assessment and Awareness Project) brings local data and modern flood modeling together to show where stormwater goes during heavy rain and storm surge, giving residents clearer information to better manage risk.

Background & History

Initiated in 2019, MAAPnext represents the most comprehensive flood risk study ever conducted in Harris County. This multi-year effort brings together cutting-edge science, local knowledge, and federal and local partnerships to transform how the region understands and prepares for flooding.

Through MAAPnext, the Harris County Flood Control District and FEMA are using updated data and advanced modeling tools to create maps that reflect how heavy rainfall causes flooding under today’s conditions.

By combining lessons from historic storms like Harvey with the latest modeling tools, MAAPnext lays the foundation for a more resilient Harris County, where residents, businesses, and community leaders can make decisions informed by the best data available.

Partnership with FEMA

MAAPnext is led by the Harris County Flood Control District in partnership with FEMA, aligning national resources and local knowledge to deliver better flood risk information, and in collaboration with local Floodplain Administrators.

MAAPNEXT PROJECT PARTNERS

MAAPnext is a collaboration that brings together national resources and local knowledge.

HARRIS COUNTY FLOOD CONTROL DISTRICT

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 this process, 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

Harris County 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.

Purpose

MAAPnext was created to give Harris County residents, businesses, and local officials the most detailed, up-to-date, and actionable flood risk information available. By updating flood maps and modeling with new data and technology, MAAPnext helps Harris County residents understand their specific flood risks by:

Providing clear, up-to-date flood risk information that residents and businesses can use to make confident, informed decisions about safety, property, and insurance.

Supporting smart planning by providing reliable data that helps communities grow safely and sustainably.

Strengthening community resilience by giving Harris County residents the tools to prepare, adapt, and recover more effectively before the next storm.

MAAPNEXT GOALS

MAAPnext is a forward-looking investment in transparency, innovation, and public safety.

The overarching goal for MAAPnext is to provide you with the flood risk information you need to make important life decisions in Harris County.

Empower

Empower Harris County residents by providing flood risk information and education, which will result in furthering the resilience of our region in the face of extreme storm and weather events.

Lead

Lead the nation in the delivery of an innovative and reliable approach to floodplain mapping and flood risk analysis.

Ensure

Ensure that the county is equipped with the most up-to-date and comprehensive floodplain mapping and flood risk tools to inform future growth, development, and mitigation strategies.

Approach

MAAPnext combines science, technology, and local insight to show how water really moves through Harris County — across bayous, streets, and areas influenced by coastal events and storm surge. This comprehensive, data-driven approach provides a clearer picture of flood risk than ever before through:

Updated rainfall estimates (Atlas 14): Using the latest National Oceanic and Atmospheric Administration data to reflect today’s rainfall patterns and intensities.
High-resolution LiDAR elevation mapping: Capturing the terrain of Harris County with nine times more detail than before, improving how we predict water flow and ponding.
Modern Hybrid 1D/2D hydraulic modeling: Simulating flooding across bayous, neighborhoods, and areas affected by tides and storm surge with greater accuracy than older models.
Integrated data and collaboration: Combining local project data, historical storm information, and FEMA standards to ensure consistency and transparency.

MAAPNEXT APPROACH

MAAPnext will incorporate different types of flooding—including riverine, urban, and coastal flooding—into the modeling to analyze and depict our flood risks in Harris County in a way that was not technologically feasible before. This new, more comprehensive type of analysis and hydrology and hydraulics modeling is heavily data dependent, and we have not previously had the technological capability to map our flood risks in this way.

What's the Difference Between 1D and 2D Hydraulic Modeling?

A hydraulic model is a mathematical model of a stream flow. These models are used to analyze stream behavior, such as flow direction, speed, and water volume. Hydraulic modeling for floodplain analysis generally falls into two categories: 1D and 2D modeling. And, MAAPnext will incorporate both types of modeling into its analysis to develop the most comprehensive flood risk data available to date.

1D Modeling

Dimensional (1D) modeling looks at a stream as a series of slices, or cross sections, perpendicular to the direction of flow. 1D models can be built with less detailed data, but require many assumptions of how water flows into and through a stream.

2D Modeling

Dimensional (2D) modeling considers the way water flows in a detailed grid of the terrain. 2D models avoid many of the assumptions required by their 1D counterparts and, as a result, provide a more accurate representation of complex hydraulic conditions encountered in the real world.

WHAT IS A HYDROLOGIC AND HYDRAULIC MODEL?

Engineers are able to utilize an integrated system of software to simulate real world conditions in our region’s bayous, streams, and channels. These simulations are completed using hydrologic and hydraulic, or H&H, models. These models predict how precipitation will impact the landscape with estimates of how deep the water will get at different locations under different weather conditions and how frequently this water depth is likely to occur.

FREQUENTLY ASKED QUESTIONS

How will communities and builders use this information?

The flood risk information developed through MAAPnext will help local governments, engineers, and developers make better-informed decisions about where and how to build safely once FEMA releases official flood maps.

Communities can use this data to plan future growth, guide infrastructure investments, and identify areas where flood mitigation projects will have the greatest impact. Builders and planners will have access to clearer, more accurate flood information, helping ensure that new structures meet modern standards for safety and resilience.

This information empowers everyone, from homeowners to policy makers, to take proactive steps that reduce flood damage and improve long-term community resilience.

When will the public be able to review new maps?

FEMA is anticipated to release the Preliminary Flood Insurance Rate Maps (FIRMs) for Harris County after completion of its federal review and publishing process. Following the release, FEMA will initiate a formal public review and appeal period.

Learn more about the FEMA map review process

What does 1D vs. 2D modeling mean in plain terms?

Flood models are computer simulations that show how water moves during a storm. MAAPnext uses hybrid 1D (one-dimensional) and 2D (two-dimensional) models to better capture complex flooding conditions.

1D modeling looks at how water moves along a defined path such as a bayou, ditch, or creek. It measures depth and flow speed along a single channel.
2D modeling simulates how water spreads across the surface — over streets, yards, and open areas — to represent flooding that can occur away from main channels in a realistic manner.

By combining both methods, MAAPnext can show how rainfall and runoff interact across thecounty, resulting in more complete and realistic flood risk information.

How do updated rainfall and elevation data improve results?

Rainfall and elevation are two of the most critical inputs in flood modeling. The updated rainfall data from NOAA’s Atlas 14 reflects more recent observations and provides revised rainfall frequency estimates for Harris County based on updated statistical analyses.

Similarly, new LiDAR elevation data, collected in 2018, offers a much more detailed 3D view of the county’s surface, including roads, neighborhoods, and drainage channels. This enhanced data helps engineers and modelers simulate water flow more precisely, improving the accuracy of flood maps and reducing uncertainty about where and how flooding may occur.

What makes MAAPnext different from past flood studies

The project integrates local data, cutting-edge modeling, and technology that were not available in earlier studies, such as updated rainfall estimates from NOAA’s Atlas 14 and high-resolution LiDAR terrain data. These improvements provide a clearer, more detailed, and more realistic picture of flood risk across every part of Harris County.