Rainfall rising in over half of India’s sub-districts, says four-decade study

Subject :Geography

Section: Indian Physical Geography

In the news:

A detailed analysis of Indian monsoon changes at the tehsil level reveals that over 55% of India’s 4,400 tehsils have experienced an increase in rainfall.
The study, conducted by the Council on Energy, Environment and Water (CEEW), analyzes high-resolution meteorological data from 1982 to 2022 recorded by the India Meteorological Department (IMD).

Study findings:

Approximately 11% of tehsils have observed decreasing rainfall, particularly during the critical southwest monsoon.
Among tehsils with reduced rainfall, about 68% experienced lower rainfall throughout the monsoon months from June to September, and 87% saw a decline during the crucial June and July period, impacting the sowing phase of Kharif crops.
Most affected tehsils are located in the Indo-Gangetic plains, northeastern India, and the Indian Himalayan region, which collectively contributes to over half of India’s agricultural production.

At district level:

An analysis at the district level in India over a period of time reveals that, collectively, the country experienced 29 ‘normal’, eight ‘above-normal’, and three ‘below-normal’ monsoon years.
However, when examining individual districts, 30% witnessed more years of deficient rainfall, and 38% saw many years of excessive rainfall.
Notably, 23 districts, including New Delhi, Bengaluru, Nilgiris, Jaipur, Kachchh, and Indore, experienced both deficient and excessive rainfall in higher proportions.
Regions historically considered dry, such as several tehsils in Rajasthan, Gujarat, central Maharashtra, and parts of Tamil Nadu, have been getting wetter, aligning with the overall trend of increasing rainfall reported by a majority of tehsils.
In the study of localized wet rainfall extremes, it was found that nearly 64% of Indian tehsils experienced an increase in the frequency of heavy rainfall days by 1-15 days per year in the past decade during the southwest monsoon.
This trend is particularly prominent in tehsils of states with the highest GDPs, including Maharashtra, Tamil Nadu, Gujarat, and Karnataka.
Additionally, in tehsils with increased rainfall during the southwest monsoon, the excess is attributed to short-duration, heavy rainfall events.

Increasingly erratic rainfall pattern:

Over the last decade (2012-2022), rainfall from the northeast monsoon, primarily affecting peninsular India from October to December, has increased by more than 10% in approximately 80% of tehsils in Tamil Nadu, 44% in Telangana, and 39% in Andhra Pradesh.
While the southwest monsoon contributes to 76% of India’s annual rainfall, the northeast monsoon accounts for about 11%.
Notably, several tehsils in Maharashtra, Goa, Odisha, and West Bengal have reported increasing rainfall during these winter months, possibly due to cyclonic activity in the Arabian Sea and the Bay of Bengal.
The monsoons play a crucial role in influencing food production, water availability, and energy transition.
Hyper-local climate risk assessments and action plans are essential for India to lead in climate action and disaster risk reduction, safeguarding lives, livelihoods, and infrastructure in the face of extreme weather events.

Source: TH