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Environment
Anger of Varunavrat
by VK Joshi
Preparations were on for celebrating Dushera when Varuna Mountain
started to slide down on the habitation of Uttarkashi on 24th September
2003. Property worth Rs.100 crores was razed to ground and 25000 people
lost their dwellings. It was perhaps the first time in August that year
that the State Government paid heed to the warnings of Geological Survey
of India (GSI) investigating the landslide hazard for the town. The
sharp eyes of the investigating experts noticed traces of movement and
the district authorities were immediately warned. Timely evacuation of
population avoided a major mishap. The fear of getting crushed under
huge boulders hurtling down from the mountaintop even now continues to
stalk the minds of the residents.
It is
quite an irony that most sacred places in the Himalayas are situated in
disaster prone areas. Uttarkashi, the gateway to Gangotri is no
exception. In the recent past Uttarkashi has seen the nature's wrath at
close quarters. A tributary of Bhagirathi River was blocked by landslide
in the mid seventies and the township had the harrowing experience of
flash floods. More recent are the Gyansu landslide in 1980 and a
devastating earthquake in 1991 are the geo-hazards that still haunt the
residents of Uttarkashi.
A landslide prone mass remains in a state of balance, as long as it
remains undisturbed. Often the so called 'developmental' projects
trigger landslides. Since Uttarksahi township is located on the bank of
Bhagirathi River and the valley is not wide enough to support further
construction or widening of the road, cutting of the toe of the hill was
resorted to make room for the multistoried hotels and tourist lodges and
also to widen the road. While the lose mountain mass is static and the
soil held in place by the roots of the trees, the place remains
tranquil. Cutting the toe of the hill was a reason enough to activate
the slide.
The geomorphology of Uttarkashi district has all the features that
induce landslides. The altitude of the area ranges from 2500 to 7138
meters. The higher reaches are snow clad. Glacial ice and seasonal snow
have carved the sharp ridges and pointed peaks. These agencies produce
plenty of rock flour and loosen the joints of rocks. The lower reaches
have steep valley sides as Bhagirathi River has cut its valley on an
earlier glacial valley. Thus the scenario is precarious, the gentler
slopes on higher reaches have the glacial flour and loosened rocks, and
the steeper slopes (>600) of lower reaches though have a forest cover
yet change in land-use pattern is alarming.
There are two phases in Uttarkashi area during which total water content
of the hill slope gets very high. One is during March-April, when the
snowmelt is considerable to soak the lose slopes and other during
monsoons. Thus water acts as a lubricant, loose material at top starts
to slide down the hill, deforestation abates the misery and the entire
mass of rocks, boulder, rock flour and trees and their stumps come
rolling on the booming population at the base.
The loss of property though a consequence of the slide is a glaring
example of self inflicted misery. The residents of the Mountain
districts seem to forget and ignore the destruction by the past
landslides and construct houses on the path of the old slides in blatant
violation of regulations for construction. This has what has happened in
Uttarkashi. It is for the residents to impose a self-discipline and
religiously follow the regulations of the land-use.
Shatanu Sarkar and his colleagues from the Central Building Research
Institute (CBRI), Roorkee, studied the slide in detail. In a paper
published in the Current Science, they state that the crown of the slide
is 700m above the road. In a satellite imagery the slide zone looks like
a trident, with the recent slide forming the middle fork.
Fortunately, this slide was anticipated as the debris had already
started falling. People and live stock were evacuated timely. Thus loss
of life was not there. Once the mass wasting process picked up momentum
there was no let up.
Varunavrat Parvat had already been affected in the past by landslides at
Tambakhani and Gyansu. These two had originated from the same crown. The
present one chose a middle path and dumped about 40, 000 to 50, 000
cubic metres of material on the buildings at the base. As per the
reports from district administration nearly 362 dwellings including
tourist hotels and lodges and part the buildings in the collectorate
compound were destroyed. Rishikesh-Gangotri road was blocked for a
length of about one kilometer at Uttarkashi. Clearing the blockage was
quite a job as the slide material kept on continuously pouring. The
slide material uprooted hundreds of trees in its wake. This compounds
the problem for the future.
Natural or anthropogenic activity on these slopes can trigger them to
slide down the hill. It is well known that earthquakes of MSK VII and
greater trigger landslides. The area is severely earthquake prone. It is
still a matter of investigation whether the present slide was instigated
by an earthquake or was it triggered by the incessant rains on preceding
days.
Anthropogenic activities are one of the major causes of landslide. It
has been found that approximately 30,000 to 40,000 cubic meters of soil
and rock needs to be excavated for construction of a kilometer of road
in Himalayan terrain. While Mussoorie—Chamba road was being constructed
it was found that construction triggered 148 landslides where the forest
cover was less than 40%. Parts where the forest cover was 60% the number
of slides was reduced to 118. Indiscriminate construction at the toe of
the mountain must have excavated unimaginable volume of soil and rocks.
A landslide under such circumstances is not an unexpected one.
Reports of geoscientists from various organizations that have
investigated the landslide have one common recommendation. The
habitation between Tambakahni and the present landslides are highly
vulnerable. It is time that they are shifted to safer areas. Engineering
solutions to contain the sliding mountain may not be possible.
The present slide was triggered after a gap of 12 years. The reasons
thereof are quite perplexing. However, the reasons are more of academic
interest. What matters is the safety of the population. People should
not take Varunavrat for granted. Settling close to the base of the
mountain may invite wrath of the Varunavrat Parvat again.
The state of Uttaranchal is on a fast track of development. It would be
worth knowing about some more landslides of the state in the next issue
that would haunt the development process for the times to come.
November 12, 2006
Image courtesy GSI
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