The International Information Center for Geotechnical Engineers

Friday, 05 October 2018 01:00

Co-seismic landslides threaten the development of hydropower plants in Nepal

Co-seismic landslides threaten the development of hydropower plants in Nepal Co-seismic landslides threaten the development of hydropower plants in Nepal.

A study reveals that the greatest risk of hydropower development in the Himalayas, one of the most beneficial regions for this energy resource, is landslides triggered by earthquakes.

In spring of 2015, a massive Mw 7.8 struck the Himalayan regions causing damage to hydropower plants and killing 9,000 people. The structures repair cost is about $200 million. Now, researcher Wolfgang Schwanghart, geologist at the University of Potsdam in Germany and his colleagues state that the severe damage to the structures was not caused due to ground shaking (the buildings were designed in line with the earthquake design regulations) but due to the landslides that the tremblor triggered. Earlier in 2015, Schwanghart had visited the Himalayan terrains and he was shocked by how many hydropower plants lie on steep slopes. "They looked rather precarious," he said.

According to the team, the steepness of river banks was a good indicator of the destruction at hydropower plants where the ground shaking was not severe. They created a map that overlaid the steepness of rivers in the Himalayan region onto a ground-shaking intensities map produced from the 2015 earthquake. It is shown that there is combined effect of ground shaking and river steepness that caused the greater damage to the constructions. This procedure mitigated the damage caused after the seismic event, confirming that the landslides threaten the sites. Schwanghart said: "They survived the quake, but got wiped out by moving debris."

The study shows that at least 25% of the hydropower projects in in the Indian, Nepalese and Bhutanese Himalayas are likely to face severe damage from co-seismic slides. However, the hazard is rarely addressed when these projects are realized.

Another research by David Gernaat, a computer modeller at the PBL Netherlands Environmental Assessment Agency in The Hague and his colleagues indicates that the selection of hydropower plants location should be re-evaluated. When only rick from earthquakes were taken into consideration in the analyses, "We have overestimated the hydropower potential in the region and underestimated the cost", says Gernaat.


Read 115 times Last modified on Friday, 05 October 2018 13:59

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