A regional data-sharing mechanism is urgently needed to manage the escalating risks of glacial outbursts in the Himalayas, says Safi Ahsan Rizvi, an expert risk analyst, former adviser to the National Disaster Management Authority (NDMA), and a retired Indian Police Service (IPS) officer with extensive experience in disaster management and risk reduction.
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Rizvi → share → management
He argues that governments must treat such cooperation as a shared public good rather than a diplomatic favour.
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governments → argue → good
In an interview, Mr Rizvi said a rock-ice avalanche clearly triggered the recent devastating floods in Nepal, though the sheer volume of water involved remains a subject of scientific investigation.
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volume → say → investigation
He warned that climate change is accelerating glacial melt, expanding high-risk glacial lakes and increasing the frequency of extreme weather events across the Himalayas.
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change → warn → Himalayas
Stressing the need for stronger early-warning systems and regional cooperation, he called for real-time information-sharing between neighbouring countries to improve preparedness and reduce disaster risks.
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he → stress → risks
Edited excerpts:
What exactly happened in Nepal, and why did it become so destructive downstream?
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it → edit → Nepal
Based on assessments by scientists across the world, this was clearly a rock-ice avalanche.
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this → base → world
A rock face failed and collapsed, bringing glacier ice down with it.
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face → fail → it
What remains uncertain is the precise trigger.
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remains → remain → ?
We do not yet know whether glacier retreat and melting destabilised the slope or whether the geological failure happened first and then affected the glacier.
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failure → know → glacier
The bigger mystery concerns the volume of water involved.
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mystery → concern → water
The flood appears to have carried several times more water than the South Lhonak glacial lake outburst flood in Sikkim in 2023.
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flood → appear → 2023
Yet satellite imagery has not identified a large pre-existing glacial lake in the area.
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imagery → identify → area
One possibility is that the landslide temporarily dammed a river upstream, creating a landslide lake that later burst.
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that → dam → lake
Even so, scientists are still trying to understand where all the water came from and how the flood reached such extraordinary speeds.
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flood → try → speeds
The terrain also played a role.
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terrain → play → role
The avalanche fell nearly a kilometre vertically before racing down steep slopes.
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avalanche → fall → slopes
The combination of gravity, water and debris allowed the flood to travel extremely rapidly downstream.
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flood → allow → gravity
A conventional GLOF occurs when meltwater accumulates in front of a retreating glacier, forming a lake that is often held back by fragile moraine material rather than solid rock.
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that → occur → rock
As glaciers shrink, these lakes can grow larger and become increasingly unstable.
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lakes → shrink → ?
Such lakes can fail for several reasons: the moraine dam may collapse, a landslide may fall into the lake and trigger overtopping, extreme rainfall may cause it to overflow, or a rock or ice avalanche may strike it.
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avalanche → fail → it
In Nepal’s case, the event appears to have involved a significant geohazard component, namely a rock-ice avalanche.
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event → appear → component
The key question remains why the rock face failed.
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face → remain → ?
Preliminary satellite-based interferometric studies suggest the slope was moving more rapidly than usual in the days before the collapse, but the precise trigger is still being investigated.
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trigger → base → collapse
Are such disasters becoming more common in the Himalayas?
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disasters → become → Himalayas
Climate change is accelerating glacier melt, which means many glacial lakes are growing in size.
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lakes → accelerate → size
As these lakes expand, the associated risks increase.
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risks → expand → ?
However, growing risk does not mean disaster is inevitable.
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disaster → grow → ?
River valleys containing high-risk lakes should have early-warning systems, evacuation plans and risk-reduction measures.
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valleys → contain → systems
In some cases, engineering interventions such as syphoning or pumping water can reduce lake levels.
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interventions → syphon → levels
The challenge is that these lakes are often located at elevations of around 5,000 metres, where work is possible only for a few months each year and requires specialised equipment.
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work → locate → equipment
This was one of the reasons why India developed national programmes for GLOF risk reduction and landslide risk mitigation.
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India → develop → reduction
The objective was to identify the highest-risk locations and systematically reduce risk before disasters occur.
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disasters → identify → risk
Q: Could warning signs have been detected before the Nepal flood?
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signs → detect → flood
There are indications that residents observed reduced water flow in the river hours before the disaster.
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residents → be → disaster
That may suggest a landslide lake was forming upstream.
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lake → suggest → ?
Mountain communities are often highly observant and can recognise abnormal changes in river behaviour.
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communities → recognise → behaviour
However, while a sudden drop in river flow might indicate danger, it does not tell people how large the resulting flood will be.
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flood → indicate → people
That is where technology becomes important.
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technology → become → ?
Satellite monitoring, sensors and warning systems can complement local knowledge and provide crucial information on hazards that communities cannot directly observe.
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communities → complement → that
…and 52 more, not listed.
The Aporia
