Amid Western Ghats landslides, revisiting need for developing early warning systems
A fresh spell of landslides across the Western Ghats during the monsoon season renewed scrutiny of India's landslide early warning infrastructure
Heavy rainfall saturated hill slopes in vulnerable stretches, including transport corridors, triggering slope failures and boulder falls
State disaster monitoring agencies issued localised landslide warnings for multiple villages and gram panchayats in Western Ghats districts based on rainfall thresholds
The recurrence of such events highlighted persistent gaps in ground-level sensor networks and real-time monitoring capacity, despite existing national guidelines on landslide risk management
National Landslide Risk Management Strategy (NDMA, 2019)
The National Disaster Management Authority (NDMA) released the National Landslide Risk Management Strategy in 2019, prepared in line with India's commitments under the Sendai Framework for Disaster Risk Reduction (2015-2030), which calls on countries to substantially increase national and local disaster risk reduction strategies. The strategy sets out a framework covering landslide inventory and hazard mapping, early warning, monitoring, and land-use regulation in hill areas.
Key Details
- Recommends zoning of mountain areas by landslide susceptibility, with no new construction permitted in hazardous zones, spring lines, first-order streams, and on slopes inclined more than 30 degrees
- Notes that building regulations in many Indian hill towns are adapted from plains-based codes (such as the Delhi Master Plan framework) and are unsuited to the geo-environmental conditions of hill terrain
- Identifies the need for landslide-specific building codes and stricter enforcement of hill-town master plans
- Assigns the Geological Survey of India (GSI) the nodal role for landslide hazard mapping and maintaining a national landslide inventory database
The recurring Western Ghats landslides illustrate the implementation gap between the 2019 Strategy's recommendations on zoning and construction regulation and actual enforcement on the ground in hill districts.
GSI's Landslide Susceptibility Mapping and Early Warning Systems
The Geological Survey of India (GSI) is the designated nodal agency for landslide hazard zonation and monitoring under the Ministry of Mines. It maintains the National Landslide Susceptibility Mapping (NLSM) programme and operates rainfall-threshold-based early warning systems for select high-risk sectors.
Key Details
- GSI conducts landslide hazard zonation mapping typically at 1:50,000 scale nationally, with more detailed 1:10,000 scale mapping for specific vulnerable sectors, and site-specific 1:1,000 scale investigations on request from state governments or road agencies
- NDMA's 2019 Strategy identified 47 priority sectors for large-scale landslide studies; GSI has since identified around 100 additional vulnerable sectors from its own database
- A key infrastructure gap flagged repeatedly is the lack of localised, real-time ground sensors (extensometers, piezometers, smart rain gauges) that can detect early soil movement and trigger automated evacuation alerts, as opposed to broader rainfall-threshold-based advisories
- State-level agencies, such as Karnataka's State Natural Disaster Monitoring Centre (KSNDMC), issue their own localised landslide warnings using rainfall and terrain data for the Western Ghats districts under their jurisdiction
The gap between broad rainfall-threshold warnings (currently the norm) and localised, sensor-based real-time early warning (the recommended but largely unimplemented standard) is the core issue the article revisits after the latest landslide spell.
Western Ghats as an Ecologically Sensitive, Landslide-Prone Region
The Western Ghats, a UNESCO World Heritage Site (natural criteria, inscribed 2012) running along India's west coast through Gujarat, Maharashtra, Goa, Karnataka, Tamil Nadu, and Kerala, is geologically classified as an escarpment of the Deccan Plateau with steep slopes, high rainfall, and lateritic/weathered soils — conditions inherently prone to slope failure, which are compounded by deforestation, hill-cutting for infrastructure, and unregulated construction.
Key Details
- The Gadgil Committee (Western Ghats Ecology Expert Panel, 2011), chaired by Madhav Gadgil, recommended classifying the entire Western Ghats into three Ecologically Sensitive Zones (ESZ I, II, III) with graded restrictions on mining, quarrying, and construction
- The Kasturirangan Committee (High-Level Working Group, 2013) scaled this back, recommending about 37% (roughly 60,000 sq km) of the Western Ghats be declared an Ecologically Sensitive Area (ESA), with a ban on mining, quarrying, and red-category industries within it
- Neither report's recommendations have been fully notified or implemented by the concerned states as of the latest draft ESA notifications, a gap repeatedly linked to recurring landslide disasters, including the 2024 Wayanad landslides in Kerala
- Key landslide contributing factors in the region: intense monsoon rainfall raising groundwater pore pressure, deforestation removing root-cohesion in topsoil, and unscientific hill-cutting for roads and rail alignments
The Western Ghats landslides recur along a fault line between scientific recommendations for ecological zoning (Gadgil and Kasturirangan reports) and the pace of ground-level regulatory implementation and early warning deployment.
- NDMA's National Landslide Risk Management Strategy released: 2019, aligned with the Sendai Framework for Disaster Risk Reduction (2015-2030)
- GSI landslide hazard mapping scales: 1:50,000 (national), 1:10,000 (vulnerable sectors), 1:1,000 (site-specific)
- NDMA identified 47 priority sectors for landslide study; GSI added around 100 more from its own database
- Gadgil Committee (2011): recommended full Western Ghats ESZ classification (three zones)
- Kasturirangan Committee (2013): recommended ~37% (~60,000 sq km) of Western Ghats as Ecologically Sensitive Area
- Western Ghats inscribed as UNESCO World Heritage Site: 2012, under natural criteria
- NDMA construction-restriction threshold: slopes inclined more than 30 degrees to the ground