And while the global population grew by 18.6% from 2000 to 2015, the population in these areas outpaced that growth, increasing by 34.1% over the same period. That means between 58 million and 86 million more people were exposed to flooding in those places over the course of 15 years.
“It’s not particularly surprising that floods would increase,” says Beth Tellman, cofounder of the flood-mapping startup Cloud to Street and the lead author of the study. “But what was striking to me was that people were moving into places where we’ve observed flooding in the past.”
The researchers looked at over 3,000 events in the Dartmouth Flood Observatory database, which logs floods reported in media coverage. They matched events that had location data to satellite images from MODIS, an instrument mounted on two NASA satellites that have each captured daily images of Earth since 2000.
The researchers used an algorithm to map where flooding had occurred by sorting out which pixels were covered with water and which weren’t. Then they added population data to see how trends in flooded areas changed over time.
Low- and middle-income countries saw the fastest population growth in flood-prone areas in the past two decades, with the highest growth rates in sub-Saharan Africa and South Asia.
Socioeconomic factors might explain some of the movement, Tellman says. Vulnerable groups might have no choice but to settle in flood zones, where land might be cheaper and more available.
By using satellite images, the researchers were able to describe the impacts of real floods more accurately than traditional models. Models can capture some types of floods, such as those that occur around rivers and on coasts. But for others caused by heavy rainfall or random events—like dams breaking, or a storm surge lining up with high tide—satellite images provide a clearer picture.
The 913 mapped floods are still only a fraction of the tens of thousands that happen globally each year. “It’s just the tip of the iceberg,” Tellman says.
MODIS takes images with a 250-meter resolution, about the length of two football fields. That means researchers couldn’t map smaller floods or those in most cities. Clouds also interfered with the image-processing algorithm, and since the satellites passed over a specific spot on Earth only once or twice each day, they missed short-term floods as well.
Newer instruments have much higher resolution and can see through clouds, says Bessie Schwarz, cofounder and CEO of Cloud to Street. These tools, along with artificial intelligence, can map floods even more accurately today. But to systematically map floods over time, the researchers had to stick with images from one source, using technology that’s been around for longer.
The effort gives scientists a clearer picture than any other resource of the scale and human impact of recent floods. And the results will be especially useful for modelers trying to predict risk, says Philip Ward, who studies flood risk assessment at Vrije Universiteit Amsterdam and wasn’t involved in the study.
Donald ’67, SM ’69, and Glenda Mattes
Don Mattes started giving to the Picower Institute for Learning and Memory at MIT before he himself was diagnosed with Alzheimer’s disease. Since his death in 2020, his wife, Glenda, has carried forward Don’s passion for its work. “My wish is that no one ever has to go through the horrors of Alzheimer’s disease ever again,” Glenda says. The Matteses have also supported the Koch Institute for Integrative Cancer Research at MIT.
Legacy sparks hope. An early key employee of Andover Controls who later ran the company’s European operations, Don visited six continents with Glenda during their 30-year marriage—often to ski or bicycle. “Don’s was a life well lived, just too short,” Glenda says. The couple made provisions in their estate plan to support the Picower Institute. After Don died, Glenda made a gift to MIT of real estate that established both endowed and current-use funds there to support research on Alzheimer’s, dementia, and other neurodegenerative diseases. Glenda is a cancer survivor, and the gift also endowed a fund in the couple’s name at the Koch Institute.
Great discoveries being made at MIT: “Don always said the best thing he got from MIT was being taught how to think,” Glenda says. “MIT is an amazing place. Picower Institute director Li-Huei Tsai and her team are doing more than looking for a treatment for Alzheimer’s. They’re looking for the root cause of the disease. I am also fascinated with the Koch’s melding of engineering and biology. The chances they are going to solve the cancer issue someday are very high.”
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Investing in women pays off
“Starting a business is a privilege,” says Burton O’Toole, who worked at various startups before launching and later selling AdMass, her own marketing technology company. The company gave her access to the HearstLab program in 2016, but she soon discovered that she preferred the investment aspect and became a vice president at HearstLab a year later. “To empower some of the smartest women to do what they love is great,” she says. But in addition to rooting for women, Burton O’Toole loves the work because it’s a great market opportunity.
“Research shows female-led teams see two and a half times higher returns compared to male-led teams,” she says, adding that women and people of color tend to build more diverse teams and therefore benefit from varied viewpoints and perspectives. She also explains that companies with women on their founding teams are likely to get acquired or go public sooner. “Despite results like this, just 2.3% of venture capital funding goes to teams founded by women. It’s still amazing to me that more investors aren’t taking this data more seriously,” she says.
Burton O’Toole—who earned a BS from Duke in 2007 before getting an MS and PhD from MIT, all in mechanical engineering—has been a “data nerd” since she can remember. In high school she wanted to become an actuary. “Ten years ago, I never could have imagined this work; I like the idea of doing something in 10 more years I couldn’t imagine now,” she says.
When starting a business, Burton O’Toole says, “women tend to want all their ducks in a row before they act. They say, ‘I’ll do it when I get this promotion, have enough money, finish this project.’ But there’s only one good way. Make the jump.”
Preparing for disasters, before it’s too late
All too often, the work of developing global disaster and climate resiliency happens when disaster—such as a hurricane, earthquake, or tsunami—has already ravaged entire cities and torn communities apart. But Elizabeth Petheo, MBA ’14, says that recently her work has been focused on preparedness.
It’s hard to get attention for preparedness efforts, explains Petheo, a principal at Miyamoto International, an engineering and disaster risk reduction consulting firm. “You can always get a lot of attention when there’s a disaster event, but at that point it’s too late,” she adds.
Petheo leads the firm’s projects and partnerships in the Asia-Pacific region and advises globally on international development and humanitarian assistance. She also works on preparedness in the Asia-Pacific region with the United States Agency for International Development.
“We’re doing programming on the engagement of the private sector in disaster risk management in Indonesia, which is a very disaster-prone country,” she says. “Smaller and medium-sized businesses are important contributors to job creation and economic development. When they go down, the impact on lives, livelihoods, and the community’s ability to respond and recover effectively is extreme. We work to strengthen their own understanding of their risk and that of their surrounding community, lead them through an action-planning process to build resilience, and link that with larger policy initiatives at the national level.”
Petheo came to MIT with international leadership experience, having managed high-profile global development and risk mitigation initiatives at the World Bank in Washington, DC, as well as with US government agencies and international organizations leading major global humanitarian responses and teams in Sri Lanka and Haiti. But she says her time at Sloan helped her become prepared for this next phase in her career. “Sloan was the experience that put all the pieces together,” she says.
Petheo has maintained strong connections with MIT. In 2018, she received the Margaret L.A. MacVicar ’65, ScD ’67, Award in recognition of her role starting and leading the MIT Sloan Club in Washington, DC, and her work as an inaugural member of the Graduate Alumni Council (GAC). She is also a member of the Friends of the MIT Priscilla King Gray Public Service Center.
“I believe deeply in the power and impact of the Institute’s work and people,” she says. “The moment I graduated, my thought process was, ‘How can I give back, and how can I continue to strengthen the experience of those who will come after me?’”