If you have plans of levelling a hill side with a JCB to build a home; it is wise to think again. Have we forgotten how an engineering college built in Munnar in the same manner was buried under a landslide? When the delicate balance of the eco system is tampered with, a calamity cannot be averted.
Be it in the form of landslides or earthquakes, nature has its own ways of getting even with man’s greed. The next doubt could be regarding the relation between global warming and landslides in the high ranges.
Across the world, the frequency and severity of natural calamities is unusually on the rise. If it is rain, then it is a downpour of terrifying magnitude like; if it is the wind, then it is as fierce as Katrina Tornado; if it is a heatwave, it gets severe; and yet again if it is in the form of cold, it gets bone-chilling.
After the Himalayas, the place with the highest probability of landslides is Kerala that lies towards the west side of the Western Ghats. This also includes parts like the west coast of Karnataka and the Konkan belt.
Apart from a 30-40 km bend along the Palakkad Ghats, the remaining stretch are ranges of the Western Ghats. Earth scientists estimates these to have formed about 15 crore years back. In Kerala, districts like Iddukki, Wayanad & Calicut are most prone to earthquakes. Right from the Panchyath level to various agencies, the people are well aware of the precautions or guidelines to follow in the instance of a disaster.Landslides due to heavy rains happen quite often and still timely warnings are not given to the people. There aren’t any systems in place for this need. Except for the Allepey district, all the other districts in Kerala feature in the list for possible landslides. In the case of Munnar, the landslides were due to the excessive encroachment, massive construction undertakings and uprooting of trees. Global warming will, in the future increase the speed and intensity of rains and this will pave way for disastrous landslides.
The landslide hit list in Kerala are the Ghats of Mannarkkad, Peerimedu, Wayanad & Periya. These Ghats happen to be as old as 250 crore years. In general, the factors which influence whether a landslide will occur typically include slope angle, climate, weathering, water content, vegetation, over-loading, geology, and slope stability. If heavy rains continues for hours together; people living in areas that lie at a 15-20 degree slant should be prepared for a probable landslide. It is better for them to be evacuated to a safer area, if weather conditions turn unfavourable. Areas that lie towards the South-West direction are more prone to landslides. Another reason is the large scale deforestation in the high ranges. Crops like tapioca or plantain requires excessive ploughing and water filled ditches for better yield. During heavy rains, water overflows in these ditches and proves detrimental too. When the vegetation in the high ranges change from large trees to yield crops, the fine ecological balance no doubt gets affected.
The high ranges where most of the rivers originate, gives rise to various smaller rivulets during the monsoons. When numerous rivulets are formed in the same area, there will be accumulation of silt and debris. This will, in the future lead to landslides.
Bunds or ledges being built in such places is another cause. Levelling areas like this to build a home is a sure call for disaster. Areas where the terrain is predominantly solid laterite are ideal for construction and terrains where mud and rocks intermingle are not fit for building purposes. It is wise to watch out for warning signs like small cracks forming on the grounds following heavy water inflow. Such cracks that run for kilometres were observed in the recent rains, in places like Peerimedu & Kuttikanam in the Iddukki district. In Pullupara, a place along the K K Road; rains washed away entire layers of mud in certain rocky areas.
When large forests are uprooted, the trees that remain seem too feeble to stop or block massive boulders. Encroachment, the greed for commercial benefits and a wave of resorts and colleges sprouting up by the minute in the high ranges of Iddukki, is nothing but man’s folly going haywire, warns the geologists. Along the Konkan belt, the huge boulders that are likely to fall or disintegrate are fastened by thick ropes of steel. A survey ought to be conducted to identify such areas in the high ranges and similar belts should be put in place.
A map prepared by the Trivandrum Centre for Earth Science Studies of the Landslide susceptible locations in Western Ghats is by itself a good reference for precautionary disaster management. Disaster prone areas from Perambra in Calicut district to South Kattakada has been featured in the map, based on the danger levels. If the government took initiatives to strictly stop people from building homes or settling in such places, mishaps could be avoided. Covering up the water sources on mountainous terrains is sure to bring in landslides. Though dense vegetation and rivulets help in preventing landslides; crops like tapioca, banana or tuber crops are not favourable to prevent landslides. Rain gardens or storm water ditches should not be built in high ranges.
Also ensure to never construct a house, building or ledge by blocking a rivulet.In the recent times, heavy rains of 15-20 cm that fall continuously for 4 to 5 hours is quite common in Kerala. In certain high range areas that are surrounded by mountains on all sides, there have been instances when the rain clouds were blocked and cut off from the rest. This led to heavy rainfalls that continued for long. The electric charge from the clouds caused lightning & thunder which in turn led to landslides. Such dangerous situations should be foreseen, hours before it can occur with the help of satellites. If the people are warned well in advance, the numbers of causalities could be brought down significantly.
The importance of the Disaster Management System that operates under the Revenue Department is the highest in situations like this. When it rains heavily and if things were to continue in the present manner; by the time the authorities report for work, a good amount of damage will already be done. The future monitoring of the monsoons & disaster control systems calls for a 24 hour danger alert mechanism.
Monsoons in the times of Global Warming are likely to be unpredictable. We could anytime expect heavy spells like the torrential downpour that flooded Mumbai in 2005 July.