TAMILNADU SEA COAST : CHANGES AHEAD

ACCOSTING THE SEA COAST 

n.nandhivarman

Nowadays seas frighten the fisher folk. For centuries fisher folk had established unassailable bond of love with seas, but in post tsunami phase every change in the sea causes nightmare. The sea recedes and people become panicky. Waves enter villages lashing out the beaches. People run hither thither for safety. Kanyakumari to Cuddalore almost for a week people of the coast spent sleepless nights and anxious days. This scenario had wakened up the social thinkers and scientists to look for solutions to coastal erosion. Changes due to continental drift are inevitable. Here too if we look at the projections made by scientists, the future world map of 100 million years and 250 million years show changes in India’s position but India always remain attached to the Asian continent. This should be viewed with consolation, because in past India was an island nation separated from Asia.

 “Our planet is a tri-axial ellipsoid, moving around the Sun in an elliptical orbit at 30 kilometers per second and rotating around its axis at 1,666 kilometers per hour which is faster than speed of sound. Such high speed rotation has resulted in polar areas being compressed towards the center and equatorial areas being bulged out” says Professor Vishal Sharma. Apart from these changes the coast of Tamil Nadu had undergone variations in the past but the present causes more concern. As per a study by the School of Earth Sciences of Bharathidasan University “Before 1.5 million years ago Sea extended up to Madurai. Around 90,000 years before Chennai, Pondicherry and Vedranyam were encircled by seas. Since sea level subsided 65,000 years ago India and Ceylon got connected. When sea level rose by 27,000 years ago both parted and when it fell by 17,000 years before joined again to part again". And amidst panic reaction to such studies, if we look at the map of coastal changes in Tamil Nadu, one could know that the coast instead of moving inwards had extended seawards. This is enough to give us fresh hope for survival braving the fury of Nature.

 VARYING TAMIL NADU COAST

The sea erosion of coast is not an India specific problem. "More than 80 percent of the world shorelines are eroding at the rates varying from centimeters to meters per year." says Orrin.H.Pelkey, Professor of Geology and Director of the Program for the study of Developed Shorelines in the Duke University, North Carolina, USA. He had authored two books and one of its titles has a message to all of us. “Living by the Rules of the Sea" is his book and it is high time we learn to live by the rules of the seas. 

A walk in the beach and breathing its salubrious breeze is world wide habit. But how many of those who visit beaches is aware on how beaches are formed? People are worried about erosion. But it is a fact that without erosion beaches could not be formed. "Without the process of erosion, we would not have beaches, dumes, barrier beaches and the highly productive bays and estuaries that owe their existence to the presence of barrier beaches" opines Jim O'Connell, the Coastal Processes Specialist of Woods Hole Oceanographic Institution. Well erosion might have helped beach formation, but it is sending alarm bells from Kanyakumari to Chennai and beyond. Let us look for some scholarly opinion in this regard. After a close study at the Pitchavaram forests near Chidambaram, M.S.Swaminathan Research Foundation reveals that "in between 1930 and 1970, the seashore had eroded by 550 meters. Between 1970 and 1992 the rate of erosion was about 12 meters." The writing on the wall is clear. In past Sirkazhi was a coastal town, which now is interior by kms. The Harbour of Choza Empire, Poompuhar is now beneath the seas. At present warning from Pitchavaram must awaken us. 

Apart from facing Nature's onslaughts with preventive measures, human errors too needs to be corrected. Sand is the food for beaches, and it is needless to say that our rivers are not supplying that food to the beaches. Human exploitation and drying of rivers depletes sand supply to beaches. Interlinking of rivers as often advised by our President A.P.J.Abdul Kalama will not only solve water crisis but will save dying beaches. 

Sea level rise is primarily due to the thermal expansion of the sea water and melting of the glaciers and ice caps. Artic Climate Impact assessment by 250 scientists says that “global warming is heating the Artic almost twice as fast as rest of the planet” United Nations sponsored Inter Governmental panel on climate change will be bringing out its fourth assessment by 2007. Changing Winds and currents in the Indian Ocean in 1990’s contributed to the global warming says a NASA study in the Geophysical Research Letters. The recent lashing of waves of Tamil Nadu coast was triggered by a storm near Australia, scientists say.

The National Hurricane Center of USA reports that “hurricanes release heat energy at the rate of 50 trillion to 200 trillion watts. This is equivalent to 10 mega ton nuclear bomb exploding about every 20 minutes.” But we in India are in one way lucky. Our coast will not be hit by hurricanes. Our cyclones are less intense. Storms that hit continental America have almost the full width of Atlantic Ocean to gain strength, since our cyclones emanate from Bay of Bengal there is neither room nor time for them to grow, and this natural phenomenon helps us in one way.

 Global warming also causes rise in sea level inundating coastal areas. We must know that most of the ice sheet rests on land that's below sea level. At a point called the "grounding line" it starts floating, thus displacing its own weight in water. And as it turns out, the line may not move much because the flow of the ice streams seems to be restrained by friction against rocks at the bottom and sides rather than the ice shelf. So if the ice shelf melts, the flow of the streams should not change appreciably. And since the volume added to the ocean depends on how much ice moves from land to water -- as determined by the grounding line -- the upshot seems to be relative stability. "The ice streams do not appear to be susceptible to the kind of unstable retreat once envisaged," says Bentley. "Their flow is largely insensitive to the presence of the ice shelf so the grounding line would remain the same."  Instead of possibly collapsing in 100 years, as was considered possible 10 years ago, Bentley says the West Antarctic Ice Sheet is more likely to collapse -- if at all -- in perhaps 5,000 years at the soonest. By this scientific prediction it becomes evident that sea level rise by global warming too will not cause more harm in near future, if we are well prepared for it with preventive measures. If governments have plans for beach nourishment with vegetation, which is the cheapest preventive measure, it will go a long way in arresting coastal erosion. Our survival instincts will save us in planet Earth, but let us strive to survive with forethought.

Courtesy: The New Indian Express-week end 4.06.2005