A University of Vermont study says flooding along the Winooski River, home to more than 140,000 Vermonters, can be expected to cause more than $2 billion in property damage in the next century — and, when climate change is factored in, the total jumps to $5.29 billion.
Floods will become considerably more frequent, the study predicts, and the brunt of the damage will be felt by lower-income households, particularly mobile home owners, because their homes are often in areas vulnerable to flooding.
However, it’s not too late to change the math, says Jesse Gourevitch, one of the study’s lead researchers and a former Ph.D. student at UVM.
The study, published Jan. 10 in the journal People and Nature, examined the potential economic cost of floods through the next 100 years in Vermont. Using a new mapping tool, it projected baseline costs of $2.13 billion in property damage in the Winooski River basin. Researchers also found that, when climate change was added to the analysis, the damage total increased to $5.29 billion.
As climate change warms Earth’s atmosphere, Vermont is expected to experience heavier and more frequent rainfall, swelling rivers and extensive flooding.
The rule-of-thumb for extreme floods used to be defined as 100-year and 500-year floods — so awful that they likely would occur only once per century or once per half-millennium. But climate change makes it likely that flooding of that magnitude will occur far more frequently.
Using light detection and ranging technology, the UVM researchers were able to create a more in-depth data set than used in previous flood maps. In addition, they calculated costs based on watershed, property type and socioeconomic group, making damage estimates considerably more precise than the data used previously.
Using the new information, the researchers found that lower-income households will be disproportionately hammered by flooding costs, and in particular residents of mobile home parks, which often are located in low-lying areas prone to flooding. Those households are less likely to have savings or flood insurance that could help them rebound from a severe flood.
The researchers said they hope their LIDAR flood mapping tool, when it is made publicly available, will be used in the future by municipalities and regional planning commissions to help plan for and minimize future flooding. LIDAR is an acronym for a combination of 3-D scanning and laser scanning, and now is commonly used to make high-resolution maps.
While the costliest flood damage will involve commercial and high-value properties, the study found, those properties tend to benefit most from wetlands restoration — an effort to minimize flood impacts. Wetlands act like sponges, absorbing excess water — and reducing the amount of floodwaters racing downstream.
One thing to be wary of, said Gourevitch, one of the study’s lead researchers, is a tendency to protect the highest-value properties in a community, rather than the properties where people would be affected the most. Using that framework, Gourevitch said, makes inequalities even worse by creating “perverse incentives for allocating resources toward the wealthiest individuals and does not help those who are most vulnerable.”
The study recommends a number of environmental and policy solutions to reduce the risk not only of increased flooding overall, but also the disproportionate impact on lower-income households. Among them are economic support and guidance for people who live in floodplains, said Nate Lantieri of the Champlain Valley of Economic Opportunity’s Mobile Home Program.
Gourevitch said the state could look into the affordability of flood insurance in vulnerable areas, and at other types of insurance in locations where flood insurance is not affordable.
In addition, prevention is an important way to minimize flood damage, and a hard look at land use could well pay off. Wetlands have gotten short shrift in many developed areas, and that was a mistake, the study suggests. Restoring wetlands could reduce flood-related damages by up to 20%, the study says; that effort would involve plantings, reshaping riverbanks, and rebuilding wetlands where they’ve been badly damaged.
A connected report by Rebeca Diehl, also a researcher at UVM, found that restoring wetlands can reduce phosphorus runoff into waterways — phosphorus that’s causing algae blooms and other problems in Lake Champlain. Diehl reported that wetlands are effective in absorbing phosphorus that otherwise would head for the lake.
While the study outlines future flooding threats, steps can be taken to change the story, Gourevitch said.
“These damages are not fixed, they’re not set in stone, and there’s a lot of opportunity to mitigate the worst impacts of climate change, both in terms of reducing carbon emissions, but then also putting measures in place that help people adapt to these impacts of climate change,” Gourevitch said.
Correction: An earlier version of this story referred incorrectly in one instance to the surname of a UVM researcher. He is Jesse Gourevitch. Also, a photo caption misstated the area covered by the projected costs of future flooding. It is the entire state of Vermont.