सेप्टेम्बर 09, 2013
The devastating landslide that hit Sindhupalchowk district in Nepal on August 2 has wiped out an entire village and affected two others, killing at least 156 people and blocking the Sunkoshi river with possibility of flash floods threatening downstream areas in Nepal and India.
A similar disaster struck Malin village in the Indian state of Maharashtra on July 30 when a landslide killed over 130 people, transforming a salubrious countryside into a corpse-strewn wreck.
Both disasters have swivelled the spotlight back on this natural calamity that routinely wreaks havoc across swathes of South Asia, especially the Himalayan region. Landslides caused rivers and lakes to burst their banks and kill almost 6,000 people in one of the country’s worst tragedies in Uttarakhand last June.
Geologists define a landslide as “a natural phenomenon causing the downward and outward movement of slope materials like rocks, soil and so on under the influence of gravity.” Erosion by rivers, weakening of rocks and soils by torrential rains heighten a region’s susceptibility to landslides.
Most of these disasters occur during the monsoon (June to September) when excess rainwater pushes the soil triggering a chain of events intensified by man-made constructions and deforestation. According to the Geological Survey of India (GSI), roughly 15% of India’s landmass is highly vulnerable to landslides.
India’s National Disaster Management Authority (NDMA) – an autonomous federal institution responsible for disaster management and preparedness in the country – lists the Himalayan states, Arakan-Yoma belt in the north east, the Meghalaya plateau, Western Ghats and Nilgiri hills as most landslide-prone areas.
The Himalayan landscape, say geologists, is especially susceptible to landslides. The mountain range was formed due to the collision of Indian and Eurasian plates. The northward movement of the Indian plate causes continuous stress on the rocks, rendering them friable, weak and prone to landslides and earthquakes.
Mountainous slopes combined with rugged topography as well as high seismic vulnerability and rainfall creates a toxic cocktail in the Himalayan region augmenting the susceptibility to landslides.
“The larger narrative that emerges from the recent Malin mishap as well as the Uttaranchal landslide last year,” explains geologist T. Nanda Kumar, formerly with NDMA, “is that it is critical to treat vulnerable slopes with extreme caution. As these are ecologically sensitive areas, construction activity here should be severely restricted here and deforestation avoided.”
According to Kumar, road construction has been found to be especially toxic to the environment of these fragile areas as it involves rock blasting which throws the rock-soil balance off kilter.
Early warning systems could reduce damage
Geologists add that what worsens India’s situation is that the country lacks a sophisticated warning system for predicting landslides. Preparedness for the hazard and a suitable warning system are vital to preventing loss of human lives and property.
Sensitive terrains across the country are also often found to be deficient in a good drainage system, thus heightening the risk to human life and property, say experts.
“Monsoonal rains,” adds Prateek Kamaraj, a geologist-scientist formerly with the Indian Council of Scientific Research, “which are critical for crops, are both a boon and a bane for many South Asian countries. Heavy downpours create floods and landslides and the problem gets aggravated with man-made constructions. Relentless rain is the trigger. But the use of heavy machinery to flatten land for agriculture or other purposes aggravates the crumbling of hilltops.”
The Indian government has identified the areas where landslides occur repeatedly through Landslide Hazard Zonation maps. The NDMA – sadly, a headless body today – has also published comprehensive guidelines on the management of landslides and snow avalanches to whittle down their destructive potential and minimise the consequential losses by institutionalising landslide hazard mitigation efforts.
The guidelines include regulatory and non-regulatory frameworks with defined timelines for all activities. These also include everyday measures like keeping direct storm water away from slopes and regular cleaning and inspection of drains for litter, leaves, plastic bags or rubble. There are tips for citizens as well: not to keep the seep holes open and to avoid storing water on rooftops.
Experts say the contribution of an aware and vigilant community that is aware of the warning signs of impending landslides is pivotal. Early warning systems should also comprise a “scientific and technological base, mechanisms of dissemination and transmission of information, and response capability on receipt of warning information,” says NDMA on its website.
Apart from these, green measures like growing more trees that can hold the soil through roots and identifying areas of rock fall as well as cracks that indicate landslides are crucial too.
“Even muddy river waters indicate landslides upstream. Ensure that the toe of the slope is not cut, remains protected and don’t uproot trees unless re-vegetation is planned. The warning signs are all out there,” says Kumar. “It’s just a matter of mitigation and management for which hazard zones have to be identified and monitoring and early warning systems put in place.
Management of landslides requires a coordinated and multi-faceted approach among many stakeholders strengthened by the requisite operational, legal, institutional, and financial support.