There are lessons to be learnt from the Uttarakhand tragedy. Topping the list is the need to immediately stop mindless construction activity in the Himalayan hills, says Nitish Priyadarshi
The disaster at Kedarnath is one of the most challenging till date. Even after a week since the nature unleashed its fury, it has been really tough for a human mind to calculate the loss.
The incident has made everyone busy. Amidst the media spotlight, the focus has been on saving human lives.
Still death has been uncountable along with other losses.
Analysis differs. While the administration insists that it was a natural calamity, environmentalists hold that this was a man-made disaster waiting to happen.
Though it was nature’s fury but the after-effects were purely man-made. It happened because geology of the area was always neglected while carrying out construction and expansion in the affected areas.
Observations suggest that inadequate consideration of geology and geomorphology during the road alignment and poor faulty engineering techniques were major factors responsible for the recent landslides and disaster.
To make a hill road, you have cut through the hill. When you cut through an unstable hill, you are creating conditions for more landslides that are a natural and frequent phenomenon.
Several hydropower projects and mining projects are going on in Uttarakhand.
The blasts along the fault lines, rocks fractured during tunnel construction or mining are leading to landslides. The debris raises the water level in the river which leads to flash floods when it rains heavily.
During the monsoon such floods have become very common and cause a lot of destruction.
A large number of trees are also cut for these projects, causing soil erosion and leading to massive landslides.
More than 220 power and mining projects are running in 14 river valleys in Uttarakhand.
Several rivers are being diverted through tunnels for these projects leading to major disasters in the state.
Himalayan hill slopes are known for their instability due to ongoing tectonic activity.
However, increasing anthropogenic intervention in the recent times appears to be contributing to terrain instability in addition to natural factors, as observed by the increasing frequency and magnitude of landslides since 1970.
In July 1970, a cloud burst in the upper catchment area led to a 15 metre rise in the Alaknanda river in Uttarakhand. The entire river basin, from Hanumanchatti near the pilgrimage town of Badrinath to Haridwar, was affected. An entire village was swept away.
During August and September 2010, Uttarakhand Himalaya witnessed large-scale slope destabilization, particularly along the roads where widening work was in progress. The landslides killed about 220 people in the entire rainy season of 2010.
The tectonic fault lines, which are active and see back-and-forth movements, have been cut in many places by roads.
More dangerously, roads are built along the fault lines at many places.
As a result, tiny seismic movements in the fault lines weaken the rocks at the base of the roads, making these stretches susceptible to cave-ins and slides.
Buildings have been constructed over flood ways, old drains and streams, blocking the natural pathways of rainwater.
It is also true that once a river is flooded it will continue to be so for 100 more years. People and local administration neglected this theory in the ongoing constructions on the old flood ways.
Another reason for the devastation at Kedarnath was that people had constructed houses on the west stream of the Mandakini river that had been dry for decades.
When the river returned to its old course following the deluge these constructions were washed away.
This area is characterised by different types of rocks, undulating terrain and cold climate.
The removal of the forest cover has accelerated the rate of erosion and mass wasting in the area.
Steeper slopes, high relative relief and presence of weathered, fractured/sheared rocks in addition to unfavourable hydrological conditions are characteristic features of the area.
A number of landslide zones are observed in the area. Debris flows, toppling failures and ground subsidence are frequently observed. Every year, a number of landslides cause heavy damage to life and property.
A very high hazard zone has already been identified by geologists near Kedardome, Bhartiyakunta peak, Brahma Gupha, Salya, Devangan and Gaurikund in Uttrakhand State. Medium hazard zones are mostly present around Okhimath, Guptkashi, Kalimath and Rambara areas.
Maximum numbers of landslides after a cloud burst have been observed to occur within a distance of one kilometre on either side of the tectonic planes. Some major fault zones in Uttarakhand are Rawanganga fault, Madhyamahashwar fault, Mandakni fault, Godwanala fault and Kaldungnala fault along which a number of landslides occur.
It has been indicated that a maximum frequency of landslides occurs along Madhyamahashwar, Godwanala and Rawanganga faults. Such areas must be taken into consideration before any construction activity is taken up.
Such disasters have both short-term and long term impact on society and the environment.
The short-term impact accounts for loss of life and property at the site and the long term impact includes changes in the landscape that can be permanent, including the loss of hills, cultivable land and the environmental impact in terms of erosion and soil loss, population shift and relocation of populations and establishments.
The frequent obstructions caused to the movement of traffic by numerous landslides during the rainy season, sometimes for days together, particularly in the Himalayan and north eastern regions of the country, bring untold misery to the people inhabiting the villages and townships in the landslide-prone hilly regions.
The author is a geologist who was previously lecturer in the Department of Environment and Water Management, University of Ranchi.
