A newly released study from Texas A&M University’s Institute for a Disaster Resilient Texas (IDRT) reinforces a key message behind the Harris County Flood Control District’s MAAPnext initiative: flood risk in Harris County extends beyond the boundaries shown on today’s effective Federal Emergency Management Agency (FEMA) flood maps. While the two efforts use different methodologies—the specific analytical approaches, data, and modeling techniques used to evaluate flood risk—they arrive at the same overarching conclusion: many properties outside FEMA’s current mapped floodplain still face meaningful flood risk. The finding reinforces a central message of MAAPnext: residents should not assume that living outside the current mapped floodplain means living without flood risk

Texas A&M’s Buyer Aware model estimates that approximately 389,500 Harris County properties have at least a 1% annual chance of flood damage. That is more than twice the approximately 184,800 properties located within the 1% annual-chance floodplain on FEMA’s current effective maps. For comparison, the draft updated floodplain developed using MAAPnext data includes approximately 345,400 properties. 

The two efforts use different methods and serve different purposes. The IDRT’s Buyers Aware tool uses historical flood insurance claims, property characteristics, and machine learning to estimate flood risk at individual properties. MAAPnext uses advanced engineering, updated rainfall data, and hydraulic modeling to estimate where flooding may occur and how deep the water could become during defined rainfall events. MAAPnext data also support FEMA’s process for updating Harris County’s official regulatory flood maps.

The broad alignment is significant: despite using different methodologies, both efforts indicate that substantially more Harris County properties face meaningful flood risk than FEMA’s current effective maps show. The results should not be treated as a property-by-property comparison or as interchangeable findings. Instead, Buyer Aware and MAAPnext offer different, but complementary information that helps residents understand the many ways flood risk is assessed.

For the Flood Control District, it also reinforces the importance of investing in updated flood science. Through MAAPnext, the Flood Control District has developed updated flood-risk information for residents, local officials and emergency managers while providing the technical foundation for FEMA’s ongoing map-update process. The goal is simple: equip the community with better information to make better decisions.

FEMA flood maps remain the regulatory standard for floodplain management and determining where federally backed mortgages generally require flood insurance. However, as both MAAPnext and the IDRT research demonstrate, flood risk is not limited to the boundaries shown on older maps. Looking at multiple sources of information gives residents a more complete picture of their potential flood risk and helps them make informed decisions about preparedness, insurance and future investments.

As flood science continues to evolve, the Flood Control District remains committed to ensuring Harris County residents have access to the best available information because understanding flood risk is one of the most important steps toward building a more resilient community. Residents can learn more about MAAPnext at https://www.maapnext.org/, explore their current mapped flood risk at https://www.maapnext.org/Interactive-Map, and speak with an insurance professional about coverage options.