HOLISTIC APPROACH TO LANDSLIDE MANAGEMENT AND MITIGATION IN THE HILL AREAS OF
- Er. Upendra Mani Pradhan
B.Sc., B.Tech(Hons.), M.Tech(R.P.), A.I.T.P.(
Landslides may rightly be called the “Tsunami of the Hills”! It is, therefore, very encouraging to note that a Landslide Hazard Workshop is being hosted on 21st. November, 2008 at
NEED FOR A HOLISTIC APPROACH :
Over 40 years of experience in Urban and Rural Planning has taught me that a simplistic approach, of building a wall here and a drain there, will not solve the problems of landslides in the hills. Numerous inter-connected factors come into play, requiring a deeper study of cause and effect that will finally lead us to a more Holistic Approach. A few points for interaction during the Workshop are given below :
1. BANNING OF POLYBAGS BY IMPOSING FINES :
This has been tried out by several municipalities from time to time, but the duration of success is barely a couple of months, after which the polybags reappear! The main objection being most of the marketing of goods are done in modern, attractive, polythene packages, which the municipalities cannot control. It is said that polythene and plastic bottles take as many as 400-700 years to just begin to breakdown in a land-fill – and they constitute millions of tons in garbage heaps of urban areas! Why not recycle this environmentally degrading waste material of global nuisance value into long-lasting attractive coloured modular-sized bricks for the ever growing building industry? Are the Tatas, Birlas, Mittals and Ambanis listening?? They can get their raw materials free of cost !
2. “JHORAS” (HILL STREAMS) - WORTH WORSHIPPING! :
It is often believed that ‘Jhoras’ are the main cause for landslides in the hills. This is far from the truth. In fact, ‘Jhoras’ form part of the natural drainage system and are meant to be Nature’s ‘safety valves’ to quickly and safely carry away rainfall runoff from large hilly catchment areas, to the rivers and seas in the plain areas below, without causing any damages along the way. ‘Jhoras’ carry water and so maintain natural vegetation like trees, shrubs, grasses along their sides to prevent toe erosion. But Man, in his infinite wisdom, cuts down such trees and shrubs; indiscriminately throws waste-matter into them; removes stone boulders, cobbles and sand; blocks the ‘jhoras’ and constructs buildings on them, thereby violating all the unwritten environmental laws of Nature! Mother Nature revolts and retaliates through landslides!
Another reason is that our hill areas are bombarded with heavy rainfall during the monsoon (2000mm to 3000mm per annum). In the natural scheme of things, this precipitation partly permeates into the soil through open ground and partly flows as surface runoff and finds its way to the ‘jhoras’. But with intense urbanization in our towns, almost all open ground surfaces have been built upon or paved by roads, courtyards and footpaths, thereby all the rainfall now flows as surface runoff and enters the ‘jhoras’ with great velocity, far exceeding their normal carrying capacity. This results in toe erosion of the ‘jhoras’ which is the precursor to a landslide.
From the above it can be seen that our forefathers were no fools! They set up ‘Devi-Sthans’ (Place of worshipping Goddess) amidst ‘jhoras’for the simple reason that our ‘jhoras’ must be faithfully conserved as they have a vital role to play in our lives. ‘Jhora’ water can also be diverted into farm lands for irrigation purposes. However, in the hills, it is better not to use this water for surface-irrigating paddy crops, because stagnant water kept in the fields over a long stretch of time, may cause landslides. From careful observation, it can also be found that the percolated water through porous soil, normally finds its way back into the ‘jhoras’ at a lower point below – this is naturally filtered water, which is used by village folk for drinking purposes. Our ‘jhoras’ are sacred entities – let us spread awareness and restore them back to their pristene glory, through planned Conservation.
3. URBANIZATION PARADOX IN THE HILLS - NOWHERE TO GO, BUT UPWARDS! :
About a week ago, Newspapers carried bold headlines about the demolition drive taken up by
The same is true for Kurseong and
Kalimpong and Mirik are better situated, as the Municipal areas are surrounded by large tracts of Khasmahal farm-lands. Sikkim Towns also have restricted space for horizontal expansion, as a result of which heavy RCC high-rise buildings are fast coming up everywhere, giving nightmares to everyone – especially during the rainy season!
The only solution to this problem is to follow Gandhiji’s “Back to the Village” policy and prepare and implement Balanced Regional Growth Plans for the entire hill areas, interspaced with ideally located and well planned Satellite Townships
4. SOIL CONSERVATION POSSIBILITIES – ROADS VERSUS ROPEWAYS :
It has been found that bamboo groves near human settlements in the hills can be dangerous. As bamboo has very shallow roots, the entire grove, having dense interlocked root system, tends to slide down as a solid mass, thereby threatening to cause big landslide damages. Some fast growing native trees with deep root system were also tried out to conserve soil on landsides. However in a few years time, the trees became very tall , big and weighty and finally the trees themselves were responsible for causing fresh landslides. What should perhaps be done is to go in for light shrubs and grasses (e.g. Vitever) with deep root system. An inventory should be made of suitable plants by the Soil Conservation and Forest Departments for immediate testing and application at landslide sites and along both sides of ‘jhoras’. Stunting of suitable deep-rooted trees to reduce their weight may also help. ‘Soil Nailing Techniques’ also sound good – but need to be thoroughly investigated for applicability in the our hills.
It is seen that major road alignments, cutting across our hills, are responsible for triggering the maximum number of landslides during monsoon period. While extensive road connectivity is undoubtedly very important, taking a road upto a certain major focal point in the rural area and then connecting this centre with other secondary villages by ropeways, for movement of both passengers and goods, could be a viable alternative for economic development of the hills, Ropeways need minimum land for putting up their towers and, therefore, cause least damages to the hill sides. While constructing roads, use of blasting technology should be avoided as much as possible, as there is risk of sliding owing to vibrations under the soil. If geological formations permit, we can also think of constructing a series of tunnels (as they have in Pune), which will also reduce travel lengths considerably.
Of late, increase of vehicle population in the hills, is simply maddening! As a result, vehicles are forced to move at crawling speed and searching for suitable space to park the car becomes an impossible and frustrating task! Better to introduce and encourage a system of mass transportation by mini-buses.
In the beginning of British Rule around 1836 – it is said that the entire hill areas of
Not much is known about “Waste lands”, but one can presume that they belong to a category of land, which has not been put to any use so far! It is high time that thorough geological studies and mapping of Waste lands are carried out immediately and appropriate steps taken to put them to good use. First and foremost, we need to identify a number of large (say 5 sq.km. - 15 sq.kms. each ) suitable, physio-geographically stable areas for setting up Planned Satellite /
6. LAND RECLAMATION IN THE HILLS - FOR OUR LANDSLIDE-FREE,
For centuries in Human history, valuable lands in the plains have been reclaimed from the sea or marshes, on which planned cities and other infrastructure have been developed (e.g.
It is observed that the most stable lands in the hills are found on hill tops and spurs. The
OUR TOWNS ARE FAST TURNING INTO UNMANAGEABLE, UNHEALTHY SLUMS, AND IF WE DON’T TAKE PROMPT POSITIVE ACTION NOW, THEN WE HUMAN BEINGS OURSELVES WILL HAVE TO FACE THE REAL DANGER OF BEING ENLISTED UNDER THE “ENDANGERED SPECIES”!
My thanks to Mr UM Pradhan for this article and I would welcome photographs/ articles from anyone for this STH blog