India’s western coast is hit by fewer cyclones than the eastern coast: Scientific reasons explained

earthobservatory.nasa.gov
  • Cyclones are among the most common natural disasters that strike India while the others include floods, draught, and landslides.

  • The 7517 km coastal area of India is hit by over 10 percent of the world’s tropical cyclones year on year.

  • The eastern coast of India is more vulnerable to cyclones than the western coast and there are strong scientific reasons why this is the case.
As per NCRMP (National Cyclone Risk Management Project), about 2% of India’s GDP and about 12% of the central government’s revenue are eroded away by the cyclones hitting the country’s long coastline. Estimates show that more than 32 crore people inhabiting the cyclone prone areas of the country are vulnerable to the hazards related to cyclone. This figure is almost one third of India’s population. In the eastern coast, the maximum damage due to cyclones happen in four states including Andhra Pradesh, Odisha, West Bengal and Tamil Nadu in addition to the UT Pondicherry.

40% of the total population in the cyclone affected regions live within 100 kms from the coastline, says the figures released by NCRMP. Cyclones bring winds of about 62 kms speed in an average. The data collected for the period between 1980 and 2000 reveal that about 370 million people in India are exposed to cyclones in the country. The peak periods that face the most cyclones are May – June and October – November. About 308 cyclones struck the coastline of India from 1980 to 2000, while only 48 cyclones crossed the western coast during this period. Recurring cyclones in the eastern coast cause huge number of deaths, loss of property, damage to infrastructure, loss of livelihood and reversal of developments. The scientific community cautions that the climate change and the resulting rise in sea level can considerably increase the coastal population’s vulnerability to cyclones.

Reasons why the western coast sees fewer cyclones than the eastern coast

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NCRMP data show that about 58 percent of the cyclones that are formed in the Bay of Bengal hit and cross the eastern coast while only 25 percent of the cyclones developing in the Arabian sea are seen approaching the western coast of India.

The temperature of the sea surface and humidity are the most important factors responsible for the formation of cyclones. The average rainfall seen by the Bay of Bengal is very high and hence the probability of the formation of cyclones in this region is also correspondingly very high.

Tropical depression is a predominant occurrence in the Indo-Gangetic plains and this natural phenomenon is highly responsible for the cyclone formation in the Bay of Bengal.

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Bay of Bengal witnesses an average temperature of 28 degree Celsius. Warm air and the fresh water pouring into the bay from the rivers in the region increase the surface temperature of the sea further resulting in tropical depression.

Cyclonic winds from other water bodies are transferred by Bay of Bengal. The lack of landmass in the Bay of Bengal basin means that the cyclones occurring in the region do not weaken and easily move towards the eastern coastline.



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