Beijing, Sep 3: Glaciers on the Tibetan Plateau are likely to become more unstable, which may lead to more collapses and collateral disasters similar to last week’s deadly flash flood at the Tibet-Nepal border, a senior Chinese climate official has warned.
The flash floods, triggered by an ice-rock avalanche near the Nepal-Tibet border on August 26, devastated towns and villages in northern and central Nepal, leaving a trail of destruction and killing hundreds.
“Over the past 60 years, the glacier area on the Tibetan Plateau has shrunk by around 24 per cent, with around 7,000 small glaciers disappearing completely,” said Gao Rong, deputy director of China’s National Climate Centre, an official body of the Chinese government.
“Looking ahead, the structural stability of glaciers across the Tibetan Plateau will decline further. Glacial disasters are likely to become more frequent and could amplify in destruction and reach through cascading effects,” Gao was quoted as saying by the Hong Kong-based South China Morning Post.
According to the figures released by Chinese officials on Wednesday, 21 people died and 541 missing in last week’s flash flood at Gyirong Port on the Tibet side of the Nepal border.
According to figures released on August 30, the missing included 261 foreigners, including 49 from India and 22 other countries, state-run Xinhua news agency reported, quoting an official briefing in Tibet.
In Nepal, the death toll due to the devastating flash floods rose to 1,252 on Thursday as more bodies were recovered from the affected areas.
The Institute of Tibetan Plateau Research, Chinese Academy of Sciences, another official body, in its report on the recent disaster, said the mudslide created by the glacier collapse travelled 22km along the valley and reached the Gyirong Port at the Tibet border crossing in just seven minutes.
Scientists stress that hazard evaluations can no longer rely solely on measuring initial collapses.
Analysing satellite and field data from Gyirong county, researchers found that collapsing ice and rock swept down the 22km valley, scouring the riverbed, dragging bank debris with it, and mixing with water, turning a high-elevation collapse into a devastating mudslide, the Post reported.
Therefore, the Chinese research suggested, disaster risk assessment in the high-mountain cryosphere – or frozen areas – must look beyond the initial failure volume of material breaking away from the mountain, and include the valley bulking potential – the capacity to increase the size of a landslide as it travels downhill – and downstream exposure.
“What truly determines risk is not just how much collapsed on the mountain, but how much can be entrained in the gully, and what critical infrastructure and populations downstream are exposed to the hazard chain,” it said.
An article published in Nature on Wednesday highlighted the urgent need to upgrade future monitoring and forecasting systems.
The disaster proved difficult to predict because it was triggered by the sudden failure of a high-altitude glacier-rock system rather than typical signals, such as extreme rainfall or rising glacial lakes, the Post reported.
Manoochehr Shirzaei, a geophysicist at Virginia Tech in Blacksburg, told Nature that conventional monitoring tools fell short in predicting such disasters, and stressed the need to have better integrated detection systems.
“What is still largely missing is a regional satellite-based system that routinely searches for accelerating glacier and rock-slope deformation and then connects that information directly to downstream flood and avalanche modelling,” the article said.
