Temporal Trends of Dry Spells in Indian Meteorological Subdivisions During Southwest Monsoon 1951–2023

Abstract

Amidst the backdrop of climate change, the monsoon rainfall pattern is experiencing alterations over time. A precise evaluation of monsoon rainfall distribution throughout the season is crucial for effective water management in agriculture, conducting drought assessments, and evaluating associated risks. Our study focused on analysing dry and wet spells within the Indian meteorological subdivisions over the past 73 years (1951–2023). It examines the spatial distribution of southwest monsoon rainfall and dry days, revealing a correlation between limited rainfall and extended dry periods, especially noticeable in regions like Western Rajasthan and Jammu & Kashmir. Vulnerability to drought is evident in regions with moderate monsoon rainfall and a high frequency of dry days. The study reveals that 65% of meteorological subdivisions experience over 60 dry days during the monsoon season, underscoring the need for a detailed analysis of dry day patterns. July and August are vital for Indian agriculture, as crop growth relies on consistent monsoonal rainfall; extended dry spells during this period cause moisture stress, affecting key stages like flowering and grain filling. The study reveals an alarming trend, with 44% of meteorological subdivisions showing an increase in dry days during August, and 29% exhibiting a similar trend for the overall monsoon season. The study also investigated the relationship between dry days and ENSO events, finding that Central and Northwest India are predominantly affected by moderate to strong events, resulting in a high probability of increased dry days. This increase in dry spells, driven by shifts in monsoon variability and intensity, reduces water availability during the growing season and raises the risk of crop failure. These findings emphasise the importance of implementing effective mitigation strategies to address the challenges posed by prolonged dry spells and their detrimental impact on crop yields.