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Climate crisis in North East India: Why are rainfall patterns changing?

Published: 13th Sep, 2021


The weather of North East India is changing. Rainfall styles over the vicinity within the ultimate century have substantially modified, ensuing in its ordinary drying up.

What is the set pattern of rainfall in India?

  • The normal date for monsoon onset over India is June 1 and for monsoon withdrawal is October 15.
  • The India Meteorological Department (IMD) closes its monsoon seasonal data on September 30. The rainfall that happens after this period is post-monsoon rainfall.
  • This means that for the last 10 years, India’s monsoon rainfall pattern has been largely skewed.
  • Monsoon is said to withdraw from a region when the following criteria are met:
    • Rainfall activity ceases over the area for five continuous days
    • an anti-cyclone establishes in the lower troposphere around 1.5 kilometres above sea level
    • moisture content reduces
  • Similar criteria are followed for the declaration of monsoon withdrawal from the country. The wind patterns over the country change from south-westerly direction to a more westerly direction when the monsoon retreats.

How the pattern is changing in North East India?

  • The North East India, which normally receives heavy rainfall during the monsoon months (June-September), has changed character for the worse.
  • The flood-drought cycle now has begun to happen within a year, especially during the monsoon.
  • The rains come in quick bursts and flood the region, followed by elongated dry periods that border on drought.

Changing of Rainfall Patterns

The India Meteorological department’s recent forecast said that regular to below-normal rainfall changed into most in all likelihood to preserve over many areas of northwest and northeast India.

  • Weather exchange inflicting drying up of land: A thing of warming that affects rainfall is drying of the land, which increases the frequency and intensity of dry intervals and droughts. An increase in moisture and the drying up collectively alternate the rainfall patterns in unpredictable methods.
  • Increased snow fall inside the Eurasian area additionally affects monsoon rainfall in North East India. Immoderate blizzard in Eurasia causes cooling of the ecosystem of the location, which triggers activities ultimately leading to a susceptible summer time monsoon season there.
  • Sea floor temperatures: This changing pattern has additionally attributed a decrease in rainfall to sea floor temperatures over the subtropical Pacific Ocean, which vary in a cycle and every segment of which lasts a decade.
  • The peak comes every two decades and is referred to as the Pacific Decadal Oscillation (PDO).
  • PDO is being influenced through global warming as it decreases the difference of temperatures most of the layers of the ocean.
  • The peak of PDO will trade from 20 to twelve years, which may have an impact on the monsoon rainfall in North East India.

What is the future weather situation for the North East location?

The future climate situations look bleak for the region.

  • Increase in temp and rainfall: They display an increase in temperatures and in rainfall, in contrast with the evidence of a decrease in rainfall over the last century.
    • Various studies have projected that temperatures within the vicinity will upward thrust through 1.8-2.1 ranges Celsius by using the cease 2030.
    • Annual mean rainfall can have upward push by 0.3-3 per cent in the same length.
  • In Assam, the Indian nation’s most susceptible to weather alternate, models are expecting a boom in temperature of 1.7-2.0 degree Celsius among 2021-2050.

What are the results of a changing rainfall pattern?

A changing rainfall sample, specifically at some point of the monsoon season, has the subsequent impacts:

  • Affects the drift of rivers: There may be a few evidence of the changing path of rivers from numerous districts in Assam which includes Lakhimpur and Dhemaji, wherein the Subansiri, Dibang (tributaries of Brahmaputra) and Brahmaputra rivers are converting publications in unexpected approaches.
    • In Arunachal Pradesh, the Papum Pare district has also been stricken by the converting course of the Dikrong River.
  • Intense rainfall occasions being caused by worldwide warming trigger a cascade of activities together with elevated soil erosion along the hill slopes devoid of wooded area cover. This will increase the floor run-off of rivers and changes their path.
  • The new courses taken by means of the rivers are frequently the historic paleo-channels that it has deserted for centuries and in which people have settled to avoid flooding.
  • Quantity of snow cover and fitness of mountain springs, All this, in flip, has an impact on livelihoods, in particular agriculture and fishing, wooded area plants boom, animal and fowl habitat (and behaviour), and other ecosystem components.
  • Threat to water and food security: The changing rainfall pattern in India is a huge concern as the country’s water and food security is at a risk. 


There are several factors that have an impact on the changing course of rivers. All of them act together, which makes the issue difficult to study.

Verifying, please be patient.

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