Two neighbors live on the same Houston street. A heavy storm moves through, bringing torrential rain. One home floods. The other stays dry.
Even if both homes take on water, the consequences could be vastly different. One might be newer, well maintained and covered by flood insurance. The other could be older, in poor condition and uninsured.
New research from Rice University shows why these differences matter — and why traditional flood risk assessments may be missing much of the picture.
In a study published in Applied Geography , researchers analyzed nearly 1 million residential buildings across Harris County and found that nearly two-thirds of the variation in flood vulnerability occurs within neighborhoods, rather than between them.
"The biggest finding is that flood vulnerability varies significantly within neighborhoods, not just between them," said Yilei Yu, a researcher at Rice's Center for Coastal Futures and Adaptive Resilience and lead author of the study. "Even homes on the same street can face very different consequences from the same storm."
Yu and her colleagues developed a Flood Vulnerability Index that looks beyond whether a home is in a flood zone. It considers four factors: potential flood depth, a home's age and condition, nearby roads that could be disrupted and financial exposure, including property values and flood insurance coverage.
"Knowing whether a home is inside or outside a flood zone doesn't tell us how much damage it could experience or how prepared the household is to recover," Yu said.
For homeowners, that means taking a closer look at their own property. Yu recommends reviewing a home's age and condition, checking whether flood insurance is in place and considering whether nearby roads are prone to flooding. Most standard homeowners insurance policies don't cover flood damage, and flood insurance is available outside designated flood zones.
The findings could also help local officials make better decisions about where to invest limited flood mitigation resources.
"Two homes in the same neighborhood may have very different vulnerability scores," Yu said. "Looking at individual properties can help communities direct resources to the people and places that need them most."
Yu and her colleagues offer additional guidance for homeowners in an article for The Conversation , explaining how residents can assess risks that traditional flood maps may overlook.
The message for Houstonians is simple: Just because your neighbor is safe doesn't mean you are, and knowing your home's vulnerabilities is the first step toward being better prepared.
