Mountain Disaster Risks

Rising temperature, a global phenomenon triggered by the excessive emissions of greenhouse gases, is having its negative ramifications on various sectors of the environment. One of them is the melting of ice mass in the Himalayan mountains.

There is a change called glacial retreat which involves disappearance of the glaciers in the lower regions and their shifting in higher elevations. It means that the permanent snowline is shifting upwards, turning the lower areas into exposed rock and soil. These unprecedented changes have been happening over the years and decades in an irreversible manner.

The ice and snow cover can return to the former level of existence only if there is a drastic cut in the emissions of greenhouse gases which may take decades and centuries if mitigation measures are taken in a concrete manner. Such steps are not in sight at present despite frequent climate meetings and discussions.

Scientific data show that the adverse impacts of global temperature rise are more visible in the mountains compared to the global average. Nepal, being a mountainous country harbouring largest number of Himalayan peaks, is prone to bear the brunt of potential disastrous events caused by ice melting. 

Scientific observations and studies have identified the formation of hundreds of glacial lakes across the Himalayan mountain range in Nepal, China, Bhutan and Pakistan. Such lakes come into existence when natural dams up in the mountains get filled with water after the increasing ice melt. Not only new lakes are being formed over the years and decades, they are ever increasing in their size and depth.

This has raised the danger of the disaster arising out of what the scientists call Glacial Lake Outburst Flood (GLOF). Glacial lakes are volatile as they have limited capacity to hold the increasing volume of water in the accumulation. Increasing temperature and further melting of the ice mass naturally raises the chance of bursting of the lakes when the rock and sediment-made moraine can no longer hold the water in place. 

As the fragile edge of a glacial lake gives way, the flashflood racing down the mountain slope unleashes immense devastations in the downstream areas. When it concerns the risks of potential GLOF events and their disastrous ramifications, it can be said that Nepal lies in highly sensitive zone. Occurrence of such events is not just fictitious and far-fetched. They have happened in the past and are likely to happen in the future as well.

A scientific report released by the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) has revealed that 63 GLOF events have occurred in Nepal's upper Koshi basin region between 1921 and 2021. This area harbours 18 potentially dangerous glacial lakes in Nepal and 24 others in China. 

An outburst of a glacial lake can cause widespread devastations in the downstream regions. People in the disaster risk area may be caught unprepared because these floods do not necessarily happen during rainy time. We see that many marketplaces, towns and other settlements are located on river banks in Nepal. They are at high risk as they are not in safe distance from the rivers. Riverside settlements along all the snow-fed rivers need to rethink from safety point of view.

An early warning system needs to be installed to notify the risk-prone people downstream when a disaster happens. Many of the roads lying close to river banks may need to be shifted to safer distance. The flood calamity faced by the Arniko Highway has taught us important lessons. Other vital infrastructures such as bridges, powerhouses and power transmission lines lying near the rivers are also likely to be destroyed in the event of such flash floods.