Changing Rainfall Patterns in an Era of Climate Change: A Multiparameter Spatiotemporal Analysis of Trends & Impacts for India

Abstract The hydrological cycle that starts with rainfall has been under major threat from the global temperature rise and climatic changes. In India, rainfall changes not only jeopardize water security but also have a major set-back for socio-economic stability. There have been attempts to decode the changing rainfall patterns in India but most of them conducted at wider spatial resolution (such as national, state, or sub-divisional level) fail to capture the essence of spatial variation in rainfall characteristics. To get a clearer understanding of change in key rainfall parameters, this paper analyses more than 197 million 0.25˚ x 0.25˚ gridded rainfall data points. The fine resolution 117 years (1901-2017) of daily rainfall data is utilized to test significant spatiotemporal trends in the quantum of rainfall and other key rainfall parameters such as rainy days, monsoon onset and withdrawal dates, occurrences of extreme rainfall events, and frequency of drought and high rainfall years. With an emphasis on changing climatic patterns since perceived climate change onset in the 1970s, the study identifies the regions with significant changes in rainfall patterns by comparing key parameters pre- & post- 1970s. The paper also highlights the major repercussions and challenges for the identified regions with significant changing rainfall patterns.