Kerala assesses land use & landslips

A UN report stresses the need for research on the role of deforestation, quarrying, unscientific road construction, slope modification, sand-mining, construction on streams, and narrowing and blocking of drainage channels in aggravating landslips and flooding

A total of 50 teams, each comprising a geologist and a soil conservator, were dispatched by the Kerala State Disaster Management Authority (KSDMA) to Kannur, Malappuram, Wayanad, Palakkad, Kozhikode, Thrissur, Ernakulam, Idukki, Kottayam, and Pathanamthitta to do a rapid assessment of whether the areas susceptible to landslip in these districts were suitable for human habitation or agricultural activity.

The teams scouted these vulnerable zones, as mapped by the Centre for Earth Science Studies, since renamed NCESS, in 2010; the areas examined by the Geological Survey of India (GSI) for its interim report in the aftermath of the 2018 floods and landslips; and where the landslips caused devastation in the latest round of monsoon fury this year, before submitting their reports to the respective District Disaster Management Authorities (DDMA) late last week.

Immediate goal

The immediate goal, say top officials, is to ascertain and limit the extent of human intervention permissible in these zones. “That’s the call of the DDMAs, in consultation with the local bodies concerned. A consolidated report received by the KSDMA will be used for policy-level action. It is not disaster vulnerability but land use that should be at the centre of discussions,” says Sekhar L. Kuriakose, KSDMA member-secretary.

Kerala, he points out, had taken the lead in launching a hazard vulnerability-linked relocation plan for the people at the risk of natural hazards on the heels of the 2018 floods.

“We were the first State to roll out such a scheme in which ₹10 lakh was offered to the affected – ₹6 lakh for purchasing land, and ₹4 lakh for building a roof over their heads. Some 701 families were identified as beneficiaries, a majority of them from landslip vulnerability zones, and 200 of them have already made use of the plan. You cannot depopulate these hills without incentivising the people living there for decades. Their farmland remains their own, but housing is in safe areas,” he adds.

Data show that there were over 5,000 landslips in the State during the 2018 rains, with some 1,800 of them occurring in revenue land.

The Post Disaster Needs Assessment report prepared by the United Nations last year for the Kerala government stresses the need for “research on the role of deforestation, quarrying, unscientific road construction, slope modification, sand-mining from river beds, construction on stream channels, narrowing and blocking of drainage channels and so on, in aggravating landslips and flooding..”

“The risk of landslips was the highest along mountain slopes that were at an incline of more than 45 degrees and where a large number of buildings and roads had been cut into the sides,” it states further.

The Rebuild Kerala blueprint brought out early this year has identified 50 taluks across the State covering an area of 5,619.7 sq km with a population of 2,799,482 people as at the risk of landslips.

In the wake of last year’s calamity, it was found that the slopes prone to landslips should be examined by geologists for relocation of most vulnerable communities. Slopes, it was maintained, should be regulated with the help of hazard zonation maps of at least 1: 5,000 scale to aid local planning by municipalities and panchayats in hill terrains.

The process is already under way, with the GSI, the techno-legal entity as identified by the National Disaster Management Plan, set to ready the landslip susceptibility map for Kerala on a 1:50,000 scale by the middle of next year, in response to a formal request from KSDMA.

“Once this is done, we will focus on the high hazard zones/panchayats to have maps of 1;25,000 or 1;10,000,” says Sachin R., superintending geologist at GSI, Thiruvananthapuram.

Strengthening of laws

Meanwhile, there is an effort on the part of the Environment Department to strengthen the laws that govern mining, including stringent measures to arrest illegal quarrying and to restore abandoned quarries.

Scientists say that it is a combination of factors that has led to the landslips in Kerala. “While climate change-induced torrential downpour is the main trigger, the process is catalysed by the character of soil, phenomena such as soil piping in which water erodes the subsurface of the soil which is rampantly noticed in several districts in the State, slope failures caused by injudicious constructions and unwitting cropping patterns,” points out John Mathai, former senior scientist of the NCESS, who was part of the team that recceed areas, including Puthumala in Wayanad, for hazard zonation mapping 10 years ago.

“The goal then was to work at the micro-level for creation of tables, with hyperlocal hazard zonation with land survey numbers which would be of use while preparing district disaster management plans. One of the proposals that came up during a workshop then was to create monsoon safety shelters for people in vulnerable zones. These shelters could be used as modern community centres at other times,” Mr. Mathai says.

Soil study plan

The KSDMA is learnt to have written to the NDMA for deployment of systems such as ground penetrating radars and differential GPS for monitoring landslip susceptibility. Also on the cards is a detailed soil technical study in these areas.

While the studies will go on, the immediate need and a lasting solution is to have an integrated approach for landslip management, says a top official. This should include land use planning, good management practices in cropping, grazing and forestry, terrain-depended road building, terracing and other contour-aligned practices in fields and plantations, all with the participation of the local communities, as envisaged in the Rebuild Kerala roadmap, he says.

But the first and foremost is a workable land use policy. A humble beginning has been made with the State sending out teams to study habitability of hazard-prone areas and also to ascertain suitable farming practices in such zones. “But it is just the first step. Land use involves scores of departments and agencies and a comprehensive policy covering all aspects alone can tackle the situation,” says the official.

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Printable version | Apr 9, 2020 1:39:21 PM |

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