Jan. 19, 2021
Study finds that dams reduce global flood exposure in climate change
A collaborative worldwide study led by researchers at the National Institute for Environmental Studies-Japan, the University of Tokyo, and Michigan State University has revealed for the first time the role of large dams in mitigating global flood risk under climate change.
Yadu Pokhrel, associate professor of civil and environmental engineering in the MSU College of Engineering and a co-author of the study, said the research developed a modeling framework that is the first of its kind.
Details of the new study have been published in the journal Nature Communications.
“We found that the number of people exposed to historically once-in-100-year floods occurring downstream of dams could be reduced by about 20 percent during the 21st century. That would spare us from the massive human and economic toll created by costly natural disasters.”
Pokhrel said flood risk is projected to increase around the world, driven by climate change and increased global population living in floodplains.
“Dams generally regulate river flows and reduce flood risks, but dam failures during unprecedented weather extremes can also cause severe downstream damages. That’s why we are interested in finding out more on ways to possibly mitigate future flooding.”
More than 50,000 large dams currently regulate about half of the world’s major river systems. Add to that, another 3,700 major dams are planned or under construction.
Pokhrel said it is critical to understand the exact role that existing and future dams will play in intensified climate extremes.
“As existing dams become older and new dams continue to be built, there is a need for comprehensive assessments that consider both potential benefits of dams in reducing flood risk and their adverse effects on the environment.”
Also see Pokhrel’s recent research, Number of people suffering extreme drought will double, in the journal "Nature Climate Change."
This work was mainly supported by Environment Research and Technology Development Fund (2RF-1802) of the Environmental Restoration and Conservation Agency (grant number JPMEERF20182R02), Japan. It was also partially supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI grant number 16H06291 and the National Science Foundation (CAREER Award, grant #: 1752729).