Regional Aspects of Deviations of South-West Monsoon Rainfall in the Seven Sister States of North-Eastern India (1981-2021)

Regional Aspects of Deviations of South-West Monsoon Rainfall in the Seven Sister States of North-Eastern India (1981-2021)

ABSTRACT The South-West Monsoon (SWM) rainfall season is a distinct climatic season for India. It holds immense climatic significance as well is the lifeline of the country in ways more than one. The months of June to September mark the advancement of monsoonal rainfall in the form of a marked rainy season for majority of the landscape of the country. The progression of SWM rainfall is observed in two flow systems – The Arabian Sea Branch and the Bay of Bengal Branch. In the current context, it is important to note that the North-eastern part of the country encounters the initial stage of the Bay of Bengal Branch which is also a mark of onset of monsoon in half of the country. Monsoonal rainfall has been exhibiting variations as a consequence of climate change and the study of average rainfall during SWM over a substantial period of time can help identify its behaviour. In this regard, the North-eastern part of the country offers a very important case to analyse owing to its geography and the fact that it has the record of highest rainfall in the world, besides being a region extremely rich in biodiversity. The current study is an examination of  average SWM rainfall and its behaviour with regards to its trends and deviations in the Seven Sister states of the country from 1981-2021. Findings have indicated that there are mixed deviation trends of rainfall but a negative trend is becoming more pronounced in the last few years.

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