New research analyzes inequities and health impacts of flooding

Flooding is the most expensive natural disaster in the United States, according to the National Oceanic and Atmospheric Administration (NOAA), costing the country more than $1 trillion in inflation-adjusted dollars since 1980. Rising sea level and more intense storms could be devastating for the more than 40 percent of Americans who live in coastal areas.

New research on the impacts of flooding and strategies for lowering those risks will be presented at the Society for Risk Analysis 2021 annual meeting, Dec. 5-9. Here are a few highlights:

More equitable flood risk protection in New Orleans

In a study examining the cost-benefit analysis of flood risk protection projects in New Orleans, Nathan Geldner of Purdue University considers the equity of residential flood risk protection. His analysis focuses on a mitigation project to elevate the foundations of single-family residences.

Most project investments are evaluated based on whether they efficiently reduce the cost of property damage. The trouble with this, Geldner argues, is that a purely economic objective may lead decision-makers to inadvertently prioritize the protection of wealthier areas over those with fewer economic resources.

His analysis compared the risk-reduction benefits from an optimally cost-effective strategy to one that minimizes normalized structure damage so that every residence is weighted equally. The results indicated that the traditional strategy assigned nearly all investments to a single majority-white neighborhood with severe flood exposure. This resulted in those white residents being substantially more protected than nearby black communities because their homes were more expensive to replace. The second strategy, using an equity-oriented approach that weighed each residence equally, resulted in a larger portion of funds going into nearby majority-Black neighborhoods as those homes were less expensive to protect.

Of all neighborhoods in New Orleans, the one with the greatest flood risk and exposure is a majority-white neighborhood outside of the levee system with moderately expensive homes. Within the New Orleans levee system, however, Black communities generally have the greatest burden of flood risk, more flood exposure, and typically smaller homes that are less expensive to elevate. "The intent of this analysis is to understand the distributional impacts of coastal protection projects and ensure they do not inadvertently worsen existing racial and ethnic disparities," says Geldner.

Health impacts of flooding

The benefit-cost analysis used to determine funding for national flood risk reduction projects primarily considers loss of life and the monetary value of physical impacts to buildings and infrastructure.

But flooding impacts public health in many other costly ways, according to the authors of a new study funded by the U.S. Army Corps of Engineers. In an effort to quantify the wide-ranging health effects of flooding, researchers are conducting a systematic review of academic articles on the human impacts of flooding published from 2000-2020.

Preliminary results of their analysis indicate that the mental health impacts of flooding include PTSD, depression, anxiety, and distress. Other health impacts include diseases, injuries, and chronic illness. The project is also looking into community-specific factors that may exacerbate or mitigate these health outcomes, such as gender, age, income, and education level.

These demographic and socioeconomic factors will help us assess how adverse health impacts of flood hazard exposure differ across vulnerable communities."

Emily Wells, study co-author, PhD student in engineering and public policy, Carnegie Mellon University

The findings will be synthesized into a modelling framework that can be adopted by engineers to estimate health impacts from floods and incorporate them into their risk assessment and project planning.