Western Himalayan at more risk than eastern Himalayan in India: IIT Madras Study

A recently developed climate risk index by researchers from the Indian Institute of Technology, Madras (IIT-M),

By Ground report 16 Mar 2024

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Western Himalayan at more risk than eastern Himalayan in India: IIT Madras Study

A recently developed climate risk index by researchers from the Indian Institute of Technology, Madras (IIT-M), highlights that the Western Indian Himalayan Region faces higher climate change risks compared to the Eastern Himalayan ranges. This innovative index is the first of its kind to utilize the latest framework from the Intergovernmental Panel on Climate Change (IPCC) to evaluate climate risk in the Himalayas. It combines both physical and socio-economic indicators for a comprehensive assessment.

Himalayas, vital, climate change, vulnerable

The Himalayas, often referred to as the "third pole" due to their extensive ice and water resources, are highly susceptible to climate change impacts. Certain areas within the Himalayas, such as the Hindu Kush Himalayan Range, are experiencing accelerated warming rates exceeding the global average. Over recent decades, there has been a noticeable decline in snow cover and glacier mass across the Himalayan region, underscoring the urgency of addressing climate change challenges in this ecologically vital area.

The researchers from IIT Madras conducted a comprehensive analysis to determine district-level climate risks by considering three key components: hazard, vulnerability, and exposure. Hazard refers to the likelihood or trend of an event occurring, vulnerability indicates the tendency to be negatively impacted, and exposure measures the extent of adverse consequences a system may face due to a hazard.

publive-image — The Western Himalayas have a higher risk index than the East, a new study shows. Photo Credit: Sharada Prasad CS/Wikimedia Commons.

Various hazards such as earthquakes, cold wave days, flood events, drought, rainfall, and lightning days were assessed using data from reliable sources like the India Meteorological Department and Census. Vulnerability was evaluated by examining disadvantaged populations likely to be harmed and assessing households' adaptive capacity to cope with changing conditions. Exposure factors included population growth rate, population density, percentage of built-up area, area under agriculture, and grazing land percentage.

Shimla most hazardous, flood-prone

The study identified Shimla district in Himachal Pradesh as the most hazard-prone due to experiencing numerous flood events from 1969 to 2019 and ranking fourth in annual snowfall days from 1981 to 2010. Following Shimla, East Sikkim stood out for its high average number of fog days and Solan in Himachal Pradesh for experiencing significant hailstorm days. On the contrary, districts in Nagaland and Mizoram showed the least hazard-prone characteristics among Himalayan districts.

Aayush Shah, the co-author of the paper, told Mongabay-India, "Each of these elements contributes crucial information that aids in understanding and mitigating potential threats. Ignoring any of these factors could lead to incomplete or inaccurate risk assessments, which would result in inadequate preparedness and response measures."

Using a method called TOPSIS, or Technique for Order of Preference by Similarity to Ideal Solution, they calculated the index. This method compares alternatives based on several different criteria using existing data and presents the best option by assessing factors that negatively and positively affect the risk. They used this method to produce separate indices for each component of the risk – hazard, vulnerability, and exposure – as well as an overall risk index by multiplying all three variables.

East Himalayas most vulnerable

In terms of vulnerability, the Eastern Indian Himalayan Region stood out, with 43 out of 62 districts classified as the most vulnerable. Dhalai district in Tripura emerged as the most vulnerable due to its inadequate adaptive capacity indicators, highlighting the urgent need for targeted adaptation strategies in these regions.

The study identified Imphal West in Manipur as the most exposed district due to its high population density and extensive built-up area. Following closely, KurungKumey district in Arunachal Pradesh ranked second due to its rapid population growth rate, while districts in Uttarakhand, specifically Hardwar and Udham Singh Nagar, ranked third due to their extensive agricultural land.

Upon combining the hazard, vulnerability, and exposure indices to form an overall risk profile, Darjeeling district in West Bengal emerged as the most "risk-prone" among all Himalayan districts. However, the study did not specify the nature of the risk. Following Darjeeling, the West and North Tripura districts showed higher risk levels.

On a broader regional scale, the Western Himalayan Region exhibited higher "risk-prone" characteristics, with around two-thirds of its districts falling into the highest and high-risk categories. Conversely, most districts in the Eastern Himalayan Region were classified as either low or low-risk districts, highlighting regional variations in climate risk across the Himalayas.

“Looking at each aspect of risk is important because it can help form more targeted policies for mitigation,” said Krishna Malakar, Assistant Professor at IIT-M and co-author of the study.

The index proves the Western Himalayan Region to be more "risk prone" on a regional scale, because it categorizes more than two-thirds of them (32 out of 47) in the highest and high-risk districts category. By contrast, the Eastern Himalayan Region has most districts (93 out of 62) categorized as either the lowest or low risk districts.