When the village of Blatten was flattened by an ice-rock avalanche last year in Switzerland (pictured above), only one life was lost. The debris flow two weeks ago in Nepal killed thousands.
While Nepal’s flooding was unprecedented, cryosphere experts are exploring whether detection and warning systems used in the Alps may be relevant to the Himalaya.
Blatten was evacuated after tiny rock movements and slope deformations were detected by interferometric radar prior to the collapse. Precise measurement equipment deployed by the monitoring company GeoPrevent helped manage the disaster.
Nepal has monsoon flood warning gauges on its rivers, but is unprepared for transboundary glacial lake outburst floods and massive ice-rock debris flows like the one that devastated the Trisuli Valley on 26 August.
“If you compare Switzerland and Nepal, there are a lot of stark differences,” says cryosphere analyst Tenzing Chogyal Sherpa. Switzerland has a dense data network that includes extensive Light Detection and Ranging (LIDAR) services and numerous ground monitoring stations.
Besides being costly, these high-tech solutions require maintenance. The Himalaya is three times as vast as the Alps, and its glaciers are more elevated and remote—making the task of installing and servicing such a network daunting.
“That’s the scenario that I hope for in Nepal,” Sherpa says, adding that data density can save lives, “but I don’t see when it will happen here.”
Until then, a continuously updated glacial inventory combined with careful land use planning and participatory flood preparedness could make Nepal’s river valleys safer.
MONITORING RISK
Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) did complete a glacial survey in 2020, but many of the 47 dangerous lakes in China and Nepal identified then have already expanded because of global warming. The inventory needs to be updated because the Himalayan cryosphere is dynamic, and risk is constantly shifting.
“We are losing glaciers almost everywhere,” explains Mohan Bahadur Chand, a glaciologist at Tribhuvan University. As permafrost continuously freezes and thaws in a warming atmosphere, the rocks that support glaciers can become unstable. Gradually, some glaciers begin to hang over the space where rocks have crumbled away, ready to collapse at any time.
Chand says such hazards are becoming more frequent, although in remote valleys and at smaller scales they often go unnoticed. Likewise, there are thousands of glacial lakes in Nepal, and not all of them pose an immediate risk to human life.
Monitoring every glacier and glacial lake precisely is impossible, but Chand agrees that a continuously updated, high-level inventory would be a good first step. Such an inventory could inform priority areas for precision monitoring and early warning system pilot projects.
FUNDING RESEARCH
Preparedness requires resources. Funding, for both research and physical equipment, is a concern in a country where meeting basic needs is the public sector’s priority. It is difficult to marshal political will and public funding to build and maintain monitoring stations, for example (especially when they do not come with a 100% safety guarantee).
However, Sherpa notes that private hydropower producers operating along Nepal’s vulnerable waterways stand to lose the most in a flood event. While some companies have invested in early warning and digital monitoring systems, many have not.
The Trisuli has a cascade of 12 hydropower stations, and all of them were either damaged or destroyed by the recent floods. Some plants had installed flood gauges upstream, but these were designed for monsoon flooding — they were no match for the 26 August deluge, which surged 100m high in some areas.
It is in the best interest of hydropower companies to better understand growing risks upstream, the floods are only the most recent in a string of climate disasters that make this clear. Encouraging private investment in not only flood preparedness systems but also cryosphere research could be a pathway towards more comprehensive and precise monitoring in the future.
ENGAGING PEOPLE
Relocation of floodplain settlements would be a difficult task in Nepal. Yet, limiting density along riverbanks, providing adequate evacuation routes, and even designating certain areas off-limits could save lives.
The recent floods demonstrate that many areas in the floodplain are uninhabitable and should be declared as such, says Sherpa, adding: “When the locals have accountability and ownership, it is more sustainable.”
Sherpa and Chand collaborated on a community-based flood warning system in which evacuation drills helped residents better prepare for a disaster scenario, making where and how to run “muscle memory.”
On 26 August, many residents who received SMS warnings from the government underestimated the scale of the flood and chose not to evacuate. Meanwhile, community-based warning systems, like the phone call to a school principal downstream, saved many lives.
Where people choose to live and how they perceive or react to risk is deeply personal. It is unlikely that putting a simple regulation down on paper will influence these patterns in Nepal.
By building on existing social infrastructure, researchers, public officials, and residents can work together to implement sustainable land use practices and early warning systems.
Only 2% of Nepal’s area is glacier-covered, but these dynamic systems pose disproportionate risk downstream. “We can always do more research,” Sherpa acknowledges, “but things are already happening quite fast.”