Saturday, June 29, 2013

Uttrakhand disaster in India is nature’s fury but consequences are man made.




A short film on causes and impact of disaster in Uttrakhand state in India.
By
Dr. Nitish Priyadarshi
Geologist. 


 


This was one of the most challenging disasters till date at Kedarnath so much so that even after few days also it was really tough for a human mind to calculate the loss. It made everyone busy. Media is covering as much as they can. Indian army, air force, navy all are focusing here to save the human lives. Still death is 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 was purely man made. It happened because geology of the area was always neglected in construction and expansion of 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 Uttarakand. The blasts along the fault lines, weathered, jointed and fractured  rocks during tunnel constructions or mining is leading to landslides.

The debris raises the water level in the river which leads to flash floods when it rains heavily. During 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.

Hill slopes in the Himalaya 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 increasing frequency and magnitude of landslides since 1970. In July, 1970 — Cloudburst in the upper catchment area led to a 15 metre rise in the Alaknanda river in Uttarakhand. 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 land-slides killed about 220 people in the en-tire 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’s also true that once river is flooded it will again be flooded in coming 100 years. People and local administration neglected this theory in ongoing constructions on the old flood ways. Other 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 characterized by different types of rocks, undulating terrain, and cool climate.
The removal of the forest cover has accelerated the rate of erosion and mass wastings 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, rockfalls, toppling failures and ground subsidence are frequently observed. Every year, a number of landslides cause heavy damage to life and property.

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 cloud burst have been observed to occur within a distance of one km on either side of the tectonic planes. Some major fault zones in Uttrakhand 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 constructions.

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.  

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