Risk of flash flood and landslide in Nepal

Scientists warn that earthquakes and aftershocks in Nepal could lead to thousands of landslides, melting glacial lakes, leading to flooding in the near future.

Risk of flash flooding and landslide in Nepal after the earthquake

"The steep terrain and high elevation in the epicenter area, along with the high frequency of shaking will trigger thousands of landslides ," said Dr. Robert Parker, a researcher at the Department of Earth and Oceanic and Oceanic Sciences. Cardiff study, he said.

Last month's 7.8-magnitude earthquake may drag thousands of landslides.(Photo: Rex)

Based on past experiences in high mountain terrain earthquakes, such as the Kashmir, India earthquake (2005) and Van Xuyen district, China (2008), a number of large landslides created a temporary dam that blocked the river. The part of the lake created by the above dams can cause great damage to the downstream area, because they can break at any time, when those temporary dams are not strong enough, usually after a few days. when the lake is full.

Nepalese officials say they have information about landslides in some areas, including Gorkha district, the epicenter, but they still do not have a complete view of the landslide situation in the region. The villages in Langtang area, west of the capital Khathmandu were buried under the landslides. Mountain villages slide down steep slopes. Experts also said there were many landslides in Tibet, along the Nepalese border, after the recent earthquake.

Satellite images also failed to show the risk and situation of landslides because this area is being covered by a thick cloud layer.

How can earthquakes in Nepal cause flooding?(Graphic: BBC)

" Large earthquakes in the mountains often leave a lot of landslides behind, depending on the variety of natural conditions that some of us still cannot explain , " said Professor Dave Petley of the University of East Anglia. , who has spent 15 years studying landslides in Nepal, said.

Seasonal rains that begin in the next few weeks will exacerbate landslides in the high mountains. " Normally, the first rains after the earthquake are the starting point of a series of landslides that took place soon after," explained the professor.

Earthquakes and snowslides also affect ice lakes in the Everest area . The tremors can weaken the lake's sediments or flatten the glacier surface above, causing great future landslides. The ice lake landslide at Dig Tsho, near Everest, took place in 1985 due to a large snow and ice erosion.

"We have concrete evidence of rock and snow avalanches in Mount Everest," said Professor Jeffrey Kargel at the University of Arizona, USA. Floodwaters from glacial lakes will quickly submerge hydropower plants and other infrastructure. Many ice lakes are scattered across the Himalayan mountains, after the last earthquake, small lakes also need special attention.

About 40 glacial lake breaks in the region last century in Nepal, Pakistan, Bhutan and China, according to the United Nations.

Location of epicenter and glacial lakes in Nepal (red square).(Graphic: BBC)