An unprecedented flash flood in the tributaries of the river Ganga in Uttarakhand on February 7 devastated the high terrain along with the dams and power projects across them. Heavy water with enormous sediments, debris, boulders and pebbles rushed down overloading the courses of the Dhauli Ganga, Rishi Ganga and Alakananda rivers to result in extreme damages to lives and developmental projects.
At least 40 people were found dead during rescue operation and over 164 are still missing, most of whom are construction workers engaged in the hydropower projects. The furious flash flood was later understood to be on account of glacial burst on the high altitude.
The disaster designate glacier burst down-poured into the Rishi Ganga hydroelectric project first and wiped it out. Subsequently, the flash flood dashed in the Dhauli Ganga river and severely damaged the Tapovana power project. Almost all the workers engaged there were thrust away and trapped by thick piles of sediments.
This disaster happened as a reminder of the deadly flood in June 2013 in the State due to heaviest monsoon rain, which killed around 6,000 people. The present flash flood caused by the glacial burst on the high-rise mountain has been proven to be an unpredictable phenomenon. Managing the pre-disaster activities like warning, evacuation in such disasters is quite unattainable, which leads to ineffective real-time rescue actions and challenging post-disaster relief and rehabilitation operations.
The abrupt outburst nature of the present glacial break flash flood leaves hardly any scope to annul the havoc that costs lives of people. The expertise rescuers including ITBP, NDRF, SDRF and Army applied all the proficient means and methods to remove buried victims, but the heavy overburden consumed lot of time that lessened the probability of life on rescue. You may categorise this disaster at par with an earthquake so far as its predictability, preparedness and rescue activities are concerned.
While the rescue operation is in full swing, experts are scheduling their research activities to find out the exact reasons of the massive flash flood. It was too early when people were talking of the cases of landslides or glacial break causing the flood. A common perception attests that voluminous water causing flash flood without rainfall must be the outcome of glacial melt. And the Uttarakhand part of the Himalayas is very much sensitive to climate change, the scientists claim.
Now, on further investigation, it is found that the flash flood is due the Glacial Lake Outburst Flooding (GLOF). Occurrence of stern incidents like GLOF can well be explained by the geology and geomorphology of the area. The eastern Chamoli district consists of the utmost mountain ranges elevating from 800 to 8,000 metres above MSL.
Nandadevi, the second highest mountain peak in India after Kanchanjangha, holds group of glaciers sitting over high grade metamorphic and volcanic rocks. Down the slope in the southern sectors, the mountains comprise of soft and loose litho types including low grade metamorphic and sedimentary rocks. Glaciers are the main feeders to the gradient rivers, which perennially supply water by steady melting and without dammed at the top. But what has occurred this time is the blockade of glacial melt in glacier lakes by moraines constituting unfastened sediments, rock and ice fragments.
On accumulation of massive water and heavy pressure generated thereof, the glacial lake broke out to release large volume of water downstream through the Dhauli Ganga with high speed accompanied by massive erosion. Hence occurred the disastrous flash flood originated by Glacial Lake Outburst Flooding.
The climate change-induced glacial retreat has produced many new glacial lakes in most part of the Hindu Kush Himalaya, which are causing GLOF, the NDMA says. Such natural phenomena of varying intensity occur often in this area. There are about 283 glacial lakes located in the Ganga basin found by the National Remote Sensing Centre during 2011-15. The recent GLOF reminds the disaster managers how challenging the management of such gigantic tragedy is. Particularly, when the timing of the glacial outburst is unknown, the preparedness and rescue operations become more indecisive and scarce. Breaching of the glacial lakes may be predicted by accessing the activation of risk factors through detailed mapping.
Accordingly, they can be classified into in a scale of stable, dangerous or alarming on basis of the climatic pattern, landscape configuration, geologic and geotechnical settings. Also, the developmental projects in the proximity should be monitored with regards to their impacts on surrounding geomorphology and structural pattern.
As per the NDMA’s recommendation, a Synthetic Aperture Radar may be installed to detect the physical conditions of glacial lakes. Thorough geological investigations with special focus on the structural mapping of active faults and lineaments must be undertaken to discern the risk owing to earthquakes and tremors. The Early Warning System, the first and foremost tool, is lacking or in nascent stage while managing GLOF. Very few instances, you may see, like the Landslide Lake Outburst Flooding (LLOF) in Uttarakhand in 1984, which was successfully handled with efficient early warning.
In case of GLOF, we are yet to catch hold the early information due to lack of monitoring mechanism of glacial lakes. Management failed at this stage leaves a little scope for further action plan and the disaster turns unprecedented, instant and disparaging.
So as the rescue operation, that also happens to ineffective without prior information and preparation. All the top rescuing agencies of the country engaged in the Uttarakhand flash flood could not succeed fast in the operation as situation demanded. Maybe, a minimum time of deployment of rescuers seems much more against the rapid outbreak of the disaster. Deep burial of victims under thick mud and sediment layer could be the hindrance for searching and rescuing work.
It is observed in many instances that local people can handle the rescue and relief operations very effectively by their instant presence. In the GLOF vulnerable areas, the locale should be trained and equipped adequately to deliver emergency services including their vigilant observation of the physical condition of lakes before they collapse.
The extreme experience in handling the recent GLOF must have given us a big lesson to develop more innovative and effective management skill for future mishaps.
(Dr Beura is Head, PG Department of Geology, Utkal University. Email: debanandabeura@rediffmail.com Mob: 91-9861213472)