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Improving Our Data

Better Data, Better Flood Risk Management

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.

MAAPNEXT GOALS

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.

MAAPNEXT DATA ADVANCEMENTS

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.

Updated rainfall and terrain data
Helps us create better analysis tools

This updated information will be used to create and run a more comprehensive type of analysis and hydrologic and hydraulic modeling (H&H) modeling, which is heavily data dependent.

MAAPNEXT TECHNOLOGY ADVANCEMENTS

Recent advancements in hydrologic and hydraulic modeling software and methodologies will allow the Flood Control District to identify and evaluate flood risks to a greater degree of accuracy and detail than was previously possible. These advancements will allow HCFCD to understand and map flooding related to bayous, creeks and other natural drainage patterns. Additionally, urban flooding, flood risk due to rainfall run-off draining through streets and neighborhoods on the way to the bayous, will also be assessed.

New modeling software and methodologies
Enhance the accuracy of our flood risk analysis

The resulting data will produce a variety of flood mapping products that will allow Harris County to better understand flooding risks to support their decisions in the future.

Light Detection And Ranging, or LiDAR, is a surveying method that measures distance to a target by scanning an area with a laser and measuring how long it takes the light to return to a sensor. This data can be used to make a 3-D map of an area.

LiDAR technology has improved since the last floodplain mapping effort in 2001. LiDAR data collected in 2018 provides 9 times greater details for development of hydraulic models and mapping of update floodplains.

lidar-plane

2001 LiDar
9-Foot Resolution

2018 LiDAR
3-Foot Resolution

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-1.PNG


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.PNG


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.

Assessment

USE NEW DATA AND TOOLS

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.

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

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 feasibile countywide 1D/2D analysis.

Updated permeability data based on 2018 aerial imagery.

Completed flood damage reduction projects will also be incorporated.

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Products

DATA-DRIVEN DELIVERABLES

MAAPnext results, including new hydrologic and hydraulic models, Flood Insurance Rate Maps, and other flood risk products developed by the Flood Control District and its team of consultants will be delivered to FEMA for review by the end of 2021.

Public Review

RESULTS

Once reviewed by FEMA, preliminary data will be made available for public review and comment before they become effective.

Impacts

PROTECTION FOR THE FUTURE

Many changes to existing mapped floodplains are expected. It is anticipated that this updated information will impact how future projects, new development, and associated flood mitigation strategies are planned and implemented throughout Harris County.