Changing Rainfall Patterns in India’s Sub-Districts

Context: 

The study of the Council on Energy, Environment and Water (CEEW), a research and policy think-tank — analyzes high resolution meteorological data spanning four decades, from 1982 to 2022 which has been recorded by the India Meteorological Department (IMD). 

• For the first time a rainfall pattern analysis at the sub-district level has been done. 

Changing Rainfall Patterns in India’s Sub-Districts (Tehsil-level): Key Findings of the Report

• Results: It points to a rapid shift in monsoon behaviour, with erratic patterns emerging due to the accelerating pace of climate change.
  • While 55% of tehsils have seen a rise (over a 10% rise) in rainfall, about 11% of them have experienced decreasing rainfall in the southwest monsoon rainfall in the last decade (2012-2022).
• Extreme Weather: 23 districts — including New Delhi, Bengaluru, Nilgiris, Jaipur, Kachchh, and Indore — experienced both extremes, with a higher number of both deficient as well as excessive rainfall years.
• Increase: Increase in rainfall during the southwest monsoon, with the excess coming from short-duration, heavy rainfall events leading to flash floods. 
  • 31% of tehsils reported an increase of four or more days of heavy rainfall annually during the southwest monsoons over the past decade compared to the previous 30 years.
• Delayed Retreat: The report finds a rise in October rainfall by more than 10%, possibly due to the delayed retreat of the southwest monsoon. 
• Locations: Drier regions like Rajasthan, Gujarat, central Maharashtra, and parts of Tamil Nadu saw a pronounced rainfall increase of over 30% during the June to September period.
• Reason of Increase: Monsoon’s convergence with a low-pressure weather system in the Himalayas in recent years has caused extremely heavy rains, due to rising temperature. 
• Reduction: Of the tehsils experiencing lower rainfall: 
  • About 68% saw reduced rainfall in all the monsoon months from June to September, 
  • About 87% showed a decline during the initial monsoon months of June and July, which are crucial for the sowing phase of kharif crops. 
• Location of reduction: The tehsils that recorded deficient rain are located in the rain-fed Indo-Gangetic plains, northeast India and the upper Himalayan region. 
• Impact of Reduction: These areas are crucial for agricultural output which contribute to more than half of India’s agricultural production and are home to fragile ecosystems particularly vulnerable to extreme climate events.

Recommendation of the Report

• Mapping monsoon performance at more localized level: Considering the high month-to-month variability and increasing occurrence of wet extremes, localized decision-making is crucial. 
  • Therefore granular level data is needed to provide comprehensive, actionable insights, enhancing disaster preparedness and response.
• Development of district-level climate action plans: In line with the MoEFCC’s 2019 directive, revision of State Action Plans on Climate Change (SAPCCs) is taking place. 
  • It is recommended  to develop district-level climate action plans, for detailed climate risk assessments in critical sectors like agriculture, water, and energy. 
• Investing in automatic weather stations and community-based recordings to capture rainfall variabilities at a hyper-local level: The need for hyperlocal climate adaptation strategies through initiatives such as the national Weather Information Network and Data System (WINDS) and community efforts. 

News Source: The Hindu