The eastern coast along the Bay of Bengal from West Bengal to Tamil Nadu basically has two seasons when the coast is hit by deep depressions and tropical cyclones of different magnitudes from category-I cyclonic storms to category-V super cyclones.
The first is just before the setting up of the south-west monsoon, primarily between April and May and the second is before the north-east monsoon from October to November.
During both seasons, Andhra Pradesh is the most vulnerable State as the 975-km coastline is sandwiched between West Bengal and Tamil Nadu.
All cyclonic storms or depression form over the North Indian Ocean (NIO) region and during the southwest monsoon, the system moves from the NIO region to Odisha or West Bengal after touching the coast of A.P. and during the northeast monsoon, the system moves towards A.P. and Tamil Nadu. In both instances, A.P. coast is affected and many a time the landfall happens over the State’s coast, be it the northern part of Srikakulam or the southern part of Nellore, says honorary professor from the Department of Oceanography and Meteorology, Andhra University, S.S.V.S. Ramakrishna Rao. A.P. being in the middle, is hit by both, he adds.
The North Indian Ocean is a potential source of energy, as it is a land-locked ocean. Most of the super cyclones and category-IV very severe cyclonic storms such as the Diviseema cyclone of 1977, the Konaseema cyclone of 1996, the Odisha super cyclone of 1999, Phailin of 2013, and Hudhud of 2014 that hit the coastal areas, originated from this part of the ocean.
Climate change
According to senior meteorologists, the NIO region was the first to experience the effects of global warming and climate change, since late 1990s.
The Odisha super cyclone that left over 10,000 dead also had a devastating effect over north coastal A.P. This was an eye opener for the scientists dealing with oceanography and climate change. It was the first category-V super cyclone that brought forward the devastating effects of global warming and climate change, says Professor Emeritus of the Department of Oceanography and Meteorology, Andhra University, O.S.R.U. Bhanu Kumar.
The potential energy released in a category four or five cyclone is equal to the energy released by 100 hydrogen bombs, says Prof. Ramakrishna.
Due to global warming, there is a change in the land and ocean temperatures and it is rising in the oceans. This is decreasing the wind shear, which is resulting in the formation of the systems at a regular basis, he explains.
The A.P. coast was directly hit or had suffered the consequences of at least 60 such storms of different magnitude in the last two decades. And as per the predictions, it is only going to increase, he adds.
In October 2014, Visakhapatnam city was hit by very severe cyclonic storm Hudhud, which had a devastating effect over the coastal districts of Visakhapatnam, Srikakulam, Vizianagaram and parts of East Godavari.
During landfall, the wind speed picked up over 185 km per hour and lakhs of trees and thousands of electric poles were uprooted. The destruction left over 60 dead across the three districts and it took weeks for the districts to limp back to normalcy.
As per the latest report by the Intergovernmental Panel on Climate Change (IPCC), Visakhapatnam is among the six cities identified by scientists that could be exposed to coastal flooding, if the sea levels rise by 50 cm, due to global warming.
Scientists in the National Institute of Oceanography and INCOIS (Indian National Centre For Ocean Information Services) say that not only Visakhapatnam but every coastal city or town now faces some vulnerabilities due to the effects of climate change.
Apart from Visakhapatnam, Kakinada and Machilipatnam also face a threat of extensive flooding, says Prof. Ramakrishna.
According to scientists and experts, in the recent past it has been observed that many of the deep depressions over the bay that could have passed off as a cyclonic storm, enhanced into category -IV storms such as Hudhud, Titli and Amphan. They not only brought in a huge amount of rain along with high wind and gales but also contributed to an increase in the sea water level. This, associated with melting of glaciers, is causing the sea level to rise, which will eventually lead to inundation of coastal areas in A.P., says Prof. Rama Rao from the Department of Bay of Bengal Studies, Andhra University.
Preparedness
The 1977 Diviseema and 1999 Odisha cyclones each led to the death of more than 10,000 people. “But subsequently, we have learnt the lesson. Today, we are much prepared and have a very advanced warning system. That is why we have been able to minimise the death count. Despite Hudhud being a category-IV storm, we had only about 60 deaths,” says a senior officer from the Visakhapatnam district administration.
Due to the early warning systems associated with evacuation procedures, the districts have been able to minimise the loss of life. “Today, we have cyclone shelters, a well-drafted disaster management plan and dedicated and professional forces such as the NDRF and SDRF to handle the eventualities,” he adds.
