Landslides in Kerala: Causes, Vulnerability & Disaster Management

Subject: GS Paper 3: Disaster Management

Context: Two years after the 2024 Wayanad tragedy, extremely heavy monsoon rainfall (August 1–2, 2026) triggered fresh landslides, mudslides, and floods across Kerala. 

Background

• ISRO Landslide Atlas (2023): Released by the National Remote Sensing Centre (NRSC), ISRO, based on landslide events recorded during 1998–2022 across the Himalayas and the Western Ghats.
  • Key Finding: Although the Western Ghats recorded fewer landslide events than the Himalayas, Kerala accounted for a disproportionately high share of landslide fatalities.

IAS coaching

About Landslide

• A landslide is the downward movement of rock, soil, earth or debris along a slope under the influence of gravity.

Classification of Landslides

• Falls: Sudden detachment and free fall of rock or debris from steep slopes or cliffs.
• Slides: Downslope movement of rock, soil, or debris along a well-defined failure surface.
  • They are broadly classified into rotational slides (curved slip surface) and translational slides (planar slip surface).
• Flows: Rapid movement of water-saturated soil, mud, and debris behaving like a fluid (e.g., debris flows, mudflows).
• Topples: Forward rotation and overturning of rock blocks or columns around a pivot point due to gravity, weathering, or erosion at the base of the slope.
• Creep: Extremely slow, continuous downslope movement of soil or weathered rock under the influence of gravity. 
  • Though gradual, it can damage roads, buildings, and other infrastructure over time.

Causes of Landslides

• Conditioning Factors: Steep slopes, geology, geomorphology, soil characteristics and topography determine inherent slope susceptibility.
• Natural Triggers: Most landslides in India are rain-induced, triggered by intense or prolonged rainfall.
  • Earthquakes, snowmelt and flood-induced undercutting of slopes.
• Anthropogenic Triggers: Hill cutting, excavation, quarrying, unscientific construction, deforestation, haphazard land use and overgrazing.

Meteorological Trigger of the 2026 Landslide in Kerala

• Offshore Trough: Extended from the south Gujarat coast to Kerala, intensifying the monsoon flow.

• Southwesterly Winds: Strong winds over the Arabian Sea enhanced moisture transport.
• Pressure Gradient: A strong north-south pressure gradient along the west coast strengthened rainfall.
• Widespread Rainfall: Heavy to extremely heavy rainfall occurred across Kerala, with several stations recording over 20.4 cm in 24 hours.
• Cumulative Rainfall: Antecedent rainfall saturated slopes, while intense rainfall acted as the immediate trigger for landslides.

Reasons for Kerala Being Highly Vulnerable to Landslides

• Fragile Western Ghats Terrain: Landslide-prone districts include Idukki, Wayanad, Kozhikode, Malappuram, Kottayam, and Pathanamthitta.
  • The region has steep slopes, deeply weathered soil, and hard rock beneath, making slopes inherently unstable.
• Soil–Rock Interface Mechanism: Rainwater infiltrates the loose soil and reaches the soil-bedrock interface.
  • Water flows between the soil and underlying hard rock, weakening the bond between them.
  • As the soil becomes saturated, shear strength decreases, leading to slope failure.
• Human-Induced Drivers: Quarrying, road construction, and hill cutting destabilise slopes.
  • Expansion of plantations alters natural drainage patterns.
  • Monocropping replaces native deep-rooted forests with tea and coffee plantations, whose shallow roots provide weaker slope reinforcement.

Click to Know UPSC Offline Courses

Way Forward

• Early Warning: Strengthen rainfall-based landslide forecasting and early warning systems.
• Promote nature-based slope stabilisation: Restore natural drainage pathways and plant deep-rooted native vegetation on vulnerable slopes to reduce erosion, improve soil binding, and minimise landslide risk.
• Land-use Planning: Enforce scientific land-use planning in vulnerable hill regions.
• Ecological Conservation: Regulate quarrying and hill cutting while restoring native forests.
• Disaster Preparedness: Promote risk-informed planning and community-based disaster management.
• Scientific Hazard Mapping: Classify areas into very low, low, moderate, high, and very high landslide hazard zones (LHZ).
  • Base zonation on slope, geology, rainfall, land use, drainage, and past landslide history.
  • Integrate LHZ maps into land-use planning, infrastructure development, road construction, and disaster risk reduction.

Check Out UPSC CSE Books

Visit PW Store