Every year hundreds of people lose their lives to landslides around the world. The most recent landslide that occurred in Jakarta, Indonesia on February 5, 2018, has impacted thousands and left two dead and eight missing (Sidiq, 2018). India too has had its share of devastating landslides which have taken numerous lives. Quite recently in August 2017, a landslide in the Mandi district in Himachal Pradesh took the lives of 46 people (TOI, 2017). Malin village in Pune, Maharashtra suffered a landslide in 2014, which destroyed a fair share of the village and killed over 150 people (GOI, 2014). The increasing population density and construction of unsafe structures in landslide-prone areas are adding to the crisis.
The danger of landslides in India is extremely grave and a report by Geological Survey of India in 2016 puts a stamp on it. According to the report, 12.6 per cent of the total land in India (excluding the snow-covered areas), approximately amounting to 0.4 million sq.km is prone to landslide hazard. Areas in North East and North West region of the Himalayas such as Sikkim, Darjeeling, Uttarakhand, Himachal Pradesh and Jammu & Kashmir fall under the vulnerable category. States such as Tamil Nadu, Maharashtra and Kerala also have some areas which are included in the susceptible zones.
To mitigate the effects of landslides, landslide hazard analysis and mapping of potential landslide areas are performed. They are used to identify multiple factors that are correlated to landslides and using the data, different zones are categorized based on their susceptibility. To execute the process, a Geographical Information System (GIS) is used, which can be used to collect, store, manipulate, analyse and display a huge amount of spatial data promptly and efficiently. To map the potential landslide zones, factors such as slope aspect, slope curvature, geomorphology and land use/ land cover are taken into account.
Natural Resources Data Management System (NRDMS), along with more than 12 institutions has initiated large-scale Geological & Geotechnical mapping along the susceptible routes in Uttarakhand in the wake of the major landslide and floods that occurred in June 2013. The institutions are working together to carry out research activities with the aim to develop a co-relation between geological and geotechnical aspects with the landslide occurrences. The study will be highly beneficial to demarcate the areas which will be safer for reconstruction and rehabilitation of the infrastructure facilities in Uttarakhand.
Figure: Landslide Locations encountered during mapping, Uttarakhand
Along with Uttarakhand, a network programme on landslide hazard mitigation and risk assessment has been launched by NRDMS, where 12 individual research projects are studying underlying causes and effects of landslides in North Eastern areas. These projects will provide critical information for adopting suitable preventive measures for mitigating landslide hazards.
Although these projects can help in mitigating the effects of a disaster, there is need of a system that helps the people before the disaster even occurs. As part of the research activities, a forewarning system for landslides is being tested in various geo-environmental conditions in the country. At present, 4 sites i.e. Munnar in Kerala, Ooty in Tamil Nadu, Rampur in Himachal Pradesh and Kunjethi in Uttarakhand are being monitored with suitable instruments to develop a co-relation between rainfall intensity with time and the threshold when a landslide takes place. Since forewarning requires site-specific characteristics, thus, no single forewarning system will work for such a big country like India. This aspect is being re-sharpened with more refinement in the observational data network.
NRDMS, under the Department of Science & Technology, is constantly working towards developing the spatial data infrastructure in the country for micro level planning across diverse terrain. To know more about NRDMS, visit wwww.NRDMS.gov.in