Decadal Variation of Southwest Monsoon Season Rainfall over Central India under Global Warming

Abstract

This study examines the decadal variation of rainfall events over the central India region from 1971 to 2020. In the present study, we used daily station-level rainfall data during the monsoon season (June-September) from 1971to 2020. Results showed that during the last two decades, extreme (> 204.5 mm/day)and very heavy (64.5 – 204.5 mm/day) rainfall events have increased alarmingly over Central India, with their peak during the decade 2001 – 2010, followed by 2011-2020. Central India has observed increased heavy rainfall category activity from July 1971 to 2020. A significant increase in rainfall activity was found in Madhya Pradesh in all three rainfall categories. The western coastal state of India - Gujarat, also showed a continuous rise in all categories from 1981 onwards. A similar trend was observed for the eastern coastal state of Odisha due to the excessive moisture supply from the Bay of Bengal. Of all the rainy-day occurrences, both heavy to very heavy rainfall events and extreme rainfall are highest in Gujarat during July and August. The extreme rainfall events were more pronounced in coastal states (Gujarat and Odisha) than the inland states like Jharkhand and Chhattisgarh. At the same time, increase in the number of depressions/cyclones was found to be increased in the last two decades. For agriculture and water management, it is essential to accurately monitor the day-to-day rainfall variability and extreme rainfall cases in a densely populated country like India.