Context: The deadly landslide in Wayanad, Kerala, highlights the region's vulnerability, as identified by the Indian Space Research Organisation's (ISRO) Landslide Atlas of India in 2023.

• Western Ghat: The Western Ghats, a UNESCO World Heritage Site, is a mountain range that runs parallel to India's western coast. Spanning six states, it is known for its rich biodiversity, dense forests, and unique ecosystems. The region is crucial for monsoon weather patterns and houses numerous endemic species of flora and fauna.

• Eco Sensitive Zone(ESZ): An Eco Sensitive Zone (ESZ) is an area surrounding protected wildlife sanctuaries, national parks, or biodiversity hotspots that is designated to minimize human impact and preserve ecological balance. These zones restrict industrial activities, regulate tourism, and promote sustainable development to protect the environment and its native species.

About the Landslide Atlas of India

• A landslide is defined as the movement of a mass of rock, debris, or earth down a slope.

• Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity.

• Landslides occur mainly in mountainous terrains where there are conducive conditions of soil, rock, geology and slope.

• The Landslide Atlas, prepared by ISRO's National Remote Sensing Centre, evaluates landslide exposure in 147 districts across 17 states and 2 Union Territories based on socio-economic parameters.

Causes

• Natural Causes that trigger it include heavy rainfall, earthquakes, snow melting and undercutting of slopes due to flooding.

• Landslides can also be caused by Anthropogenic Activities such as excavation, cutting of hills and trees, excessive infrastructure development, and overgrazing by cattle.

• In India, rainfall-induced landslide events are more common.

Key Findings

• Kerala's Rankings: Wayanad ranked 13th, while Thrissur, Palakkad, Malappuram, and Kozhikode ranked 3rd, 5th, 7th, and 10th respectively.

• Top Ranking: Rudraprayag in Uttaranchal ranked first, focusing on landslide-prone areas in the Western Ghats and Himalayan regions.

Possible reasons behind Wayanad Landslide

• Heavy rainfall

• Extremely heavy rainfall, a fragile ecology particularly vulnerable to landslides, and steadily increasing population pressures all combined to trigger multiple landslides.

• The region received more than 140 mm of rainfall in the 24 hours between the mornings of Monday and Tuesday, about five times more than what is expected.

• Heavy rains during the monsoon season trigger landslides in Kerala almost every year.

Hilly terrain with sharp slopes

• The whole of western Kerala, which is a hilly terrain with sharp slopes, is susceptible to landslides.

• According to the landslide atlas released by the Indian Space Research Organisation's (ISRO) National Remote Sensing Centre in 2023, 10 out of the 30 most landslide-prone districts in India were located in Kerala, with Wayanad ranked 13th.

• The terrain here has two distinctive layers, a layer of soil sitting atop hard rocks.

• When a lot of rain happens, the soil gets saturated with moisture and water reaches the rocks and flows between the soil and the rock layers.

• This weakens the force that binds the soil to the rocks and triggers the movement.

Loss of green cover

• A 2021 study on landslide hotspots in India revealed that 59 per cent of the total landslides in Kerala occurred in plantation areas.

• Loss of forests increase the fragility of the terrain, especially in areas prone to heavy rains in the western ghats.

Climate change

• Climate scientists have pointed towards the warming of the Arabian Sea as one of the causes for the extremely heavy and unpredictable rain patterns in the state.

• The southeast Arabian Sea is becoming warmer, causing the atmosphere above this region, including Kerala, to become thermodynamically unstable.

• Scientists have noticed a trend of deep cloud systems forming due to the warming of the Arabian sea.

• This causes extremely heavy spells of rain in shorter periods of time, increasing the risk of landslides, especially when these intrude into land.

Vulnerability of Kerala

• Kerala is prone to heavy rains and flooding, with an estimated 14.5 per cent of land area seen as vulnerable.

• The Kerala State Disaster Management Authority (KSDMA) has identified 1,848 square kilometres, 4.75 per cent of the state’s total area, as High Landslide Hazard Zone.

• About 8 per cent of the area in the Western Ghats in the southern state is labelled as a critical zone for mass movements, including debris flow, landslides, rock falls and slumps.

• Western Ghats: High population and household density increase vulnerability despite fewer landslides compared to the Himalayan regions.

• Soil Cover: Landslides in the Western Ghats are primarily influenced by soil cover on steep slopes.

• Globally, landslides rank third in terms of deaths among natural disasters.

• India is among the four major countries where the risk of landslides is the highest.

About Madhav Gadgil Committee Report

• The Madhav Gadgil Committee Report, recommended that 64% of the Western Ghats be designated as ecologically sensitive zones.

• The report specifically highlighted the need to protect Kerala's highly sensitive areas, which were marked for no-development, and criticised the state government for ignoring these recommendations.

• The Madhav Gadgil Committee Report was submitted in 2011.

• However, the recommendations are not implemented yet.