Nepal Khabar Online February 17, 2021
Akosombo Dam on the Volta river in Ghana is spilling water through six floodgates because of the all time high water level in the dam.

Flood, natural disaster, is already a problem around the world due to its havoc nature. It is projected that it will even rise due to the climate change and population growth. A new collaborative study led by researchers from National Institute for Environmental Studies, the university of Tokyo, and Michigan State University exposed that there is some role of dams for mitigating flood risk under climate change. Research indicated that flood exposure to the people decrease by approx. 15% once in 100 years in downstream of dams during the 21st century.

According to the research, there are about 3700 major dams which are planned or under construction. And it is necessary to plan the current and future dam landscapes must be integrated into existing flood modeling frameworks. According to the river flood simulations, the number of people exposed to the historical once in 100 year flood below dams were 7.2 and 13.4 million and average over 2006-2099 given a low and a medium high greenhouse gas emission trajectory (RCP 2.6 and 6.9 resp. ). The population exposed to flooding below dams decreased on average by 16.3% and 12.8% for the two trajectories compared to simulations not accounting for the flow regulations produced by dams. At the end of the 21st century, the decrease was further extended to 20.6% and 12.9% respectively.

There are numerous negative environmental and social impacts of dams, but with comprehensive assessments it is possible to increase the benefits and reduce the adverse effects for sustainable development of water resources.

  1. Source : Julien Boulange, Naota Hanasaki, Dai Yamazaki, Yadu Pokhrel. Role of dams in reducing global flood exposure under climate changeNature Communications, 2021; 12 (1) DOI: 10.1038/s41467-020-20704-0

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