Over 80 Million People Live in Flood Zones

As urban centers around the world grow, sea levels rise, and extreme weather becomes more common, "the proportion of the world’s population living in flood zones has increased exponentially," writes Linda Poon. According to new research published in the journal Nature, "[f]rom 2000 to 2015, the number of people living in flood-prone areas increased by an estimated 58 million to 86 million," a 24% increase.

"The study uses a trove of satellite imagery to map 913 major flood events since 2000, which the flood monitoring startup Cloud to Street says offers planners a more detailed scope than flood projection models of the crisis facing cities." The resulting maps "combine flooding imagery with global human settlement data to show population growth in flooded areas, which the researchers attribute to increased economic development and migration to flood zones."

"Nearly 90% of the floods analyzed occurred in South and Southeast Asia, with high flood exposure in areas that have large river basins and that saw large population growth, like Dhaka and Bangladesh. In 32 countries across four continents, the population exposed to flood is increasing at a rate higher than total population growth, with India and some countries in Africa experiencing particularly large increases in flood exposure."

Flooding also poses a risk to basic infrastructure. "From the recent flooding of New York City’s nearly 120-year-old subway to Zhengzhou’s metro system in China’s Henan province, much of the urban infrastructure built decades ago is not designed to handle the kind of historic rainfall that cities often see today."

The researchers are making the database public "to help policymakers improve the accuracy of global flood risk models, which can be rife with uncertainties," and "improve the quality of vulnerability assessments, which in turn can increase the efficacy of climate adaptation measures."