India’s extreme rainfall ‘corridor’

Subject :Geography

Section: Physical geography

Context:

The Indian monsoon has well-known features, such as the onset of the monsoon, the withdrawal, the active and break periods, and the low-pressure systems (or monsoon depressions).
Every aspect of the monsoon has been affected by global warming.

Where does extreme rain occur?

India’s monsoon forecasts rely heavily on its relation to the El Niño and the La Niña phenomena, although this relation holds only about 60% of the time.
A new study has found that a remarkable stationary element exists in terms of where synchronised extreme rainfall events occur.
The large-scale extreme rainfall events are actually simultaneous or near-simultaneous heavy rain episodes that are strewn across a ‘highway’ that extends from parts of West Bengal and Odisha to parts of Gujarat and Rajasthan.
This corridor has remained unchanged from 1901 to 2019.

What does this mean for the monsoon’s stability?

Traditional statistical methods tend to miss the complex relations between multiple nodes of rainfall centres.
This study shows that the most active nodes have followed this ‘highway’ for more than a century.
The link lengths between nodes, or the scales of synchronicity, have remained nearly constant, at an average value of about 200 km.

What do the findings mean for forecasts?

Researchers had earlier considered that stationary elements no longer exist in climate systems because of global warming. But the Indian monsoon is able to synchronise heavy rain events as well as stick to the ‘highway’ for such a long time.
One of the main factors for this synchronised and stable heavy rainfalls is the range of mountains running along the west coast and across Central India.
This finding will help in better predictions and forecasts of heavy rainfall.
It will also help in reducing risk in the fields of agriculture, water, energy, transportation, health, etc.