Rainfall dynamics observed over India during last century (1901-2020) using innovative trend methodology

This study investigates the spatio-temporal distribution and trends of seasonal rainfall for different meteorological sub-divisions (MSDs) of India using statistical analysis and the innovative trend analysis (ITA) method. The gridded dataset of daily rainfall for 120 years from 1901 to 2020 was obtained from the India Meteorological Department (IMD) and analysed using statistical results of mean rainfall, standard deviation, coefficient of variation, skewness, kurtosis, maximum seasonal rainfall, percent deviation of rainfall, number of rainy days, rainfall intensity, rainfall categorization, trend detection, and cross-correlation coefficients. The period was divided into three quad-decadal times (QDT) of 40 years each (i.e., 1901-1940: QDT1, 1941-1980: QDT2, and 1981-2020: QDT3). A general decrease in the number of rainfall events was observed in all the seasons except for a few MSDs of northwest India showing a rise throughout the pre-monsoon season in recent times (QDT3). Significant trends were detected using the ITA method in seasonal rainfall in nearly all the MSDs of India. Our findings are highlighting the qualitative and quantitative characteristics of seasonal rainfall dynamics at the MSDs level which will be useful for comprehending the rainfall dynamics as impacted by climate change and climate variability in India, and may further lead the policymakers and stakeholders for making the best use of available water resources.