KOCHI: Kerala could certainly learn a thing or two from Aizawl, the capital of Mizoram. While Kerala continues to battle landslides in its hill ranges, this small city in the Northeast has made much progress in what seems elusive to Kerala.
After a devastating landslide in 2013 that tragically took 17 lives, Aizawl’s municipal corporation sprang into action, crafting comprehensive landslide hazard maps and enforcing strict slope modification regulations.
Despite being in an earthquake-prone area that has experienced several landslides and loss of lives, these new measures have allowed Aizawl to significantly reduce disaster risks, setting a commendable example for Kerala and the rest of the country.
Hari Kumar, Regional Coordinator for South Asia, GeoHazards International, pointed out that the recent landslide in Wayanad’s Chooralmala was a natural event triggered by intense, concentrated rainfall. “While the concentrated rainfall caused the landslide, the debris flow’s quantity and speed could not be predicted with current technology,” he said.
Kumar, however, noted that the number of people in harm’s way would have been smaller if there had been clear regulations to prevent construction within the floodplains of rivers, which is missing in most parts of the country. He emphasised that human activities, such as constructions along riverbanks, exacerbated the risk, although this landslide itself was a natural event.
Kumar, who had served on the National Disaster Management Authority (NDMA) Task Force when the National Landslide Risk Management Strategy 2019 was formulated, told TNIE that most landslide maps available across the country are at a scale of about 1:50,000, which is not helpful for planning or regulatory purposes.
“Though Kerala has prepared district-level hazard maps, I am unsure if these can be used for development control. It is important to create maps of at least 1:5,000 scale in populous locations in our hilly regions and to establish specific regulations for each zone in the map (maybe extreme, high, moderate, and low hazard),” he said.
Aizawl faces a high risk of earthquakes from several major active faults. Annual monsoon rains trigger frequent, sometimes deadly, landslides. Even a moderate earthquake can unleash hundreds of landslides at once.
“The Aizawl story started with the development of an earthquake scenario, a scientific study conducted by GeoHazards International (GHI) and the Disaster Management and Rehabilitation Department of Mizoram,” Kumar said.
“This brought together international, national, and local teams of experts to study the effects of a plausible earthquake striking Aizawl. As can be seen from any photograph of Aizawl, the earthquake risk to the built environment is evident. However, one of the disturbing findings was that the earthquake would trigger hundreds of landslides within the Aizawl municipal corporation (AMC) area during the few seconds of shaking.
That awakening motivated decision-makers to work with various departments to develop a landslide risk reduction plan for Aizawl. The AMC first prepared 1:10,000 scale maps, followed by 1:5,000 scale maps. They are now aiming for 1:1,000 scale maps. AMC also developed and enforced the slope modification regulations, empaneled geologists, and brought the community on board through awareness programmes,” he said.
The Aizawl Municipal Corporation (Site Development and Slope Modification) Regulations, 2017, came into effect on April 4, 2017, to regulate human activities such as slope cutting, filling, increasing groundwater penetration into slopes, and disposing of sewage and drainage onto slopes in a poorly controlled manner, to avoid increasing slope instability.
C Lalmalsawma, Assistant Town Planner of AMC, emphasised the importance of these regulations, given Aizawl’s high earthquake-prone region and frequent landslides. “While natural landslides cannot be prevented, man-made ones can be reduced through proper scientific methods,” he said.
“First, we established a landslide committee, and fortunately, experts from GHI gave technical support in formulating the regulations and landslide hazard maps. We then hired geologists on a contract basis to support our efforts,” Lalmalsawma explained.
“Our procedure requires applicants to submit a Geo-technical Assessment report prepared by accredited laboratories before applying for site development. We have also empaneled geologists, issuing them technical licences and enabling them to submit applications on behalf of applicants. Our in-house geologists conduct site visits and process files.
Additionally, we have a Geologic Review Board (GRB) comprising senior geologists. The GRB reviews high-risk landslide areas, providing recommendations on construction types, floor numbers, and soil and slope conditions. This ensures that development is safe and sustainable,” he added.
Lalmalsawma noted that the corporation has significantly reduced the occurrence of human-made landslides, although it cannot claim a 100% success rate. “The reduction is drastic, and the community has recognised the efforts and is willing to cooperate due to prior experiences,” Rinpuii Tlau, a resident of Aizawl said.
Additionally, the AMC strictly bans all slope-cutting work or excavation from July to October during the rainy season to mitigate landslide risks.
Kumar pointed out that since the regulations were enforced in 2017, there have not been any landslide-related deaths until this year when some slides occurred during Cyclone Remal.
“I think it is a great achievement of Aizawl Municipal Corporation and the people of Aizawl to take this forward. Though NDMA cited Aizawl as a model to be followed by hill towns across the country, I don’t think there has been enough replication of this model in other states,” he said.
Kumar feels that studying the Aizawl model for landslide risk reduction would benefit Kerala and the rest of the country. The Kerala Post Disaster Needs Assessment report after the 2018 floods and landslides also recommended this. “We need to avoid creating risks rather than managing disasters after,” he added.
Strict measures
April 4, 2017
Aizawl Municipal corporation (Site Development and slope Modification) Regulations, 2017, came into effect
Applicants must submit a geo-technical assessment report for site development
In-house geologists conduct site visits and process files
Geologic Review Board (GRB) reviews high-risk landslide areas, providing recommendations on construction types, floor numbers, and soil and slope conditions
(concluded)
