Rising waves threaten our coasts, govt does little

A high tide at Marine Drive promenade in Mumbai. pti

Septuagenarian Bankim Hazra doesn’t believe in doomsayers who claim Sundarban delta is being slowly devoured by the rising waves. For decades, he has heard of such reports but none of the islands had actually been wiped off the map.

“I have been hearing about the sinking of the Ghoramara island for decades. Now I am close to 70 years and the island is still there, isn’t it,” says Hazra, a local politician.



Fifteen hundred kilometres down south, Jagan, a middle-aged fisherman, differs. A resident of Bommiyarpalayam village close to the scenic East Coast Road in Tamil Nadu, Jagan has seen too many houses in his hamlet collapsing due to an eroding coast.

Read: ‘Mumbai sinking’ is not just an alarm
 

“More than 70 houses have been completely spoiled as the ocean made ingress in the past 10 years,” he says looking haplessly at the hamlet sandwiched between the road and the sea.

Both Hazra and Jagan are right from their standpoints. Sea level rise due to an increasingly warmer planet is a reality and threat to millions living on the coast. But its mechanism is gradual and complex for people to consider it as an immediate threat.

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The science, however, is unambiguous. “While sea level has risen globally by around 15 cm during the 20th century, it is currently rising more than twice as fast – 3.6 mm per year – and accelerating. Sea levels will continue to rise for centuries. It could reach around 30-60 cm by 2100 even if greenhouse gas emissions are sharply reduced and global warming is limited to well below two degrees Celsius, but around 60-110 cm if greenhouse gas emissions continue to increase strongly,” the UN Intergovernmental Panel on Climate Change said in a report released in September.

In Sundarban, Ghoramara is the worst-affected island that lost about 50% of its landmass due to coastal erosion and sea-level rise between 1975 and 2012. As locals and researchers raise red-flags, the hungry sea continues to chip off the island.

“The erosion at Ghoramara shows no signs of slowing down. The northern and eastern part of the island is being eroded at an alarming rate. We have informed the state government several times but so far no substantial steps have been taken to either save the island or rehabilitate the residents,” says Sanjit Sagar, head of the Ghoramara Gram Panchayat.

The West Bengal island is not an isolated case. In recent decades, the rate of sea-level rise has accelerated all over the world, due to growing water inputs from ice sheets in Greenland and Antarctica, in addition to the contribution of meltwater from glaciers and the expansion of warmer sea waters. The impact would be on 680 million people living in coastal areas.

Rising sea level threatens coastal zones through a range of hazards including permanent submergence of land; more frequent or intense coastal flooding; enhanced coastal erosion; loss and change of coastal ecosystems; salinisation of soils, ground and surface water; and impeded drainage.

Coastal cities and mega-cities are at risk. According to the Intergovernmental Panel on Climate Change report, four Indian cities – Mumbai, Kolkata, Surat, and Chennai – are among 45 coastal cities where even a marginal rise would lead to flooding.

Read:  Islanders are fighting a losing battle

The once-in-a-century kind of flooding would be far more common. In vulnerable areas, even minor flooding would turn out to be a severe flood event.

The signs are visible on the west coast. Surat, one of the most industrialised and one of India’s fastest-growing cities has been witnessing massive floods while soil erosion in the neighbouring coastal areas like Valsad and Navsari has been rampant. Several nearby areas like Danti, Machiwad, Borsi and Udwada (a famous Parsi town that houses the Fire temple) have witnessed the Arabian sea eating away their land, homes and temples over the last two decades. Destruction can be spotted all along the coast.

“There are changes in the coastline that we witnessed in the past three to four decades. Soil erosion is something that has been eroding the land. Soil erosion in the whole of south Gujarat is the biggest threat and it needs to be taken care of,” said Kamlesh Yagnik, chief resilience officer at Surat Municipal Corporation whose job is to tackle issues arising due to climate change.

Similar signatures are there on the east coast too though scientists like Satheesh Shenoi, director of the Indian National Centre for Ocean Information Service, Hyderabad, say local factors are equally responsible.

Precarious situation

In Puducherry, 40-50 mt of the beach has gone missing putting those living near the shore in a precarious position. As the beach shrunk, fishermen are forced to park their boats far away and shift their houses due to the fear of their home being consumed by the ocean. “The erosion in Puducherry is mostly man-made as it accelerated due to a harbour that disturbed the equilibrium,” notes Shenoi, who studied the area extensively.

Observations since 1961 show average global ocean temperature has increased up to a depth of 3,000 mt and the ocean has been absorbing more than 80% of the heat added to the climate system. Widespread decreases in glaciers and ice caps have contributed to sea-level rise beside the melting of Greenland and Antarctic ice sheets.

The average sea-level rise along the Indian coast is about 1.7 mm, per year, which is close to the global average.

The region most vulnerable to accelerated sea-level rise is the low lying coral atolls of Lakshadweep archipelago while the Karnataka coast is the least vulnerable.

The east coast with a larger frequency of storms and lower continental slopes is more vulnerable.

From the tide gauge data maintained by Indian port authorities, the highest sea-level rise was recorded at Diamond Harbour (5.16 mm/year) in the Sundarban areas of West Bengal while the least rise was seen in Chennai (0.3 mm/year) and Mumbai (0. 74 mm/year).

The alarming figure recorded at Diamond Harbour, according to Shenoi, could be due to a combination of sea-level rise and subsidence (natural land sinking).

Haphazard interventions

As the sea-level rises, a common refrain on both sides of the coast is of government inaction. Jan Imhoff, a civil engineer who lives in the Auroville township of Puducherry, said while growing human presence couldn’t be avoided due to rising population, things turned worst when interventions are carried out haphazardly.

“The risks to the coastal areas could not be ascertained at the moment in the absence of an accurate digital elevation model as the existing ones have big error margins,” said Shenoi.

Just 600 mt from the Town Beach in Puducherry stands Vaithikuppam village protected by a natural wall of rocks. “Since the Cyclone Thane in 2011, the rocks that used to defend us began to roll over to the sea allowing water to cross the boundary. Many houses were indeed consumed by the ocean,” said Natarajan, 55, a local fisherman.

While Puducherry had protected itself by constructing sea walls and immersing a reef on the new beach, the nearby villages have no such protection. “The government had plans to construct sea walls and groins, but nothing has moved in the past few years. The villages need sea walls if they want to be in peace,” Imhoff added.

“But can the government really do anything to control nature,” wondered Hazra.

(With inputs from Soumya Das in Kolkata, Satish Jha in Surat, E T B Sivapriyan in Puducherry)

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