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By Ranit Mukherji Rising sea levels in the Sundarbans have seen excess salinity in the soil and river water, leading to the slow death of the magnificent mangroves that protected these 102 islands and the hinterland from the cyclones that sweep across the Bay of Bengal. Massive replantation programmes are the only solution, and community plantations are already under way on some islands
The mangroves of the Sunderbans are dying. This is bad news for Kolkata and the rest of Gangetic West Bengal, still reeling from the onslaught of Cyclone Aila. For the people here, it will mean less peaceful days and more stormy nights. With the mangroves gone, cyclones generated in the Bay of Bengal and sweeping across the Bangladesh hinterland will hit them much harder than they have done so far. Are we ready for our second innings with a tsunami? Perhaps not. Environmentalists believe prevention is better than cure. How big is the scare really? Let’s take a look at this little landmass off the southwest coast of Bangladesh -- Jhorkhali. The name translates as ‘land of storm’. Everything here lives under constant threat. Humans. Farmland. Cattle. In less than five years, random cyclones have ransacked homes, destroyed cattle, and swept dead marine life ashore. It’s a signal that all production cycles here must come to a standstill. Whatever little human habitation there was has moved further up, putting pressure on the socio-economic setup of the mainland. If you want to walk on the grey shores of Jhorkhali, take off your shoes to feel the slimy, gooey, anaerobic mud that intermittently shows up the dead remains of mangrove trees. Geologists have taken samples of this mud and the near-fossilised mangrove biomass to try and find out what went wrong in Jhorkhali. The results are startling: there has been a remarkable increase in salt content. Rains apart, these mangrove belts are watered by freshwater rivers like the Jhila, Raimangal, Ichhamati and Harenbhanga. With sea levels rising due to global warming, the water in these rivers is being replaced by seawater. Saline water now sweeps across the fragile mud embankments of the Sunderban islands, adding to the existing salinity of the soil. Around 400 years ago, the islands of the Sunderbans used to be guarded by 3,700 km of mud-flats. Four centuries on, many of these mud-flats have disappeared. And saline levels in the water have increased substantially, making it impossible for the remaining few embankments to act as shields any longer. Geologists say that in many of the mangrove wetlands, the amount of freshwater reaching the mangroves has declined considerably from the late-19th century onwards due to diversion of freshwater upstream. Some say that the Bengal basin is slowly tilting east due to geo-tectonic movements, forcing more freshwater input into the Bangladesh Sunderbans. Images captured by Cartosat reinforce the contention among marine experts that geo-tectonic movements could be responsible for the increase in salinity as well. As a result, salinity in the Bangladesh Sunderbans is much lower than in the Indian Sunderbans. The gross area of this forest land, once measuring around 16,700 sq km, has dropped to two-thirds of its original size, thanks to increased salinity wreaking havoc on most of the 102 islands. Consequently, only 40 islands are today capable of supporting human habitation. Salinity has destroyed regeneration density, say officials of the state forest department. Lean riverwater flows have failed to push away the salty seawater. The Sunderbans tract, as we see it today, is of recent origin. Its sub-stratum consists mainly of quaternary-era sediment, sand and silt mixed with marine salt deposits and clay. As a result, the soil of the Sunderbans mangrove forests differs from other mainland soils as they have been subjected to the effects of salinity and waterlogging. The consequence? Serious salinity has arrested the growth of mangroves, stultifying or killing them, and destroying the natural biotic shield that protects thousands of Gangetic and marine villages. It’s left them exposed to frequent storms that sweep across the Bay of Bengal. This has been the case with most of the 64 species of mangrove in the region. On average, the height of mangroves like Keora ranges between 20 and 30 feet, while that of species like Abicinia marina grow to around 15 feet. “These heights are sufficient to serve as breaks to slow down rapidly advancing cyclones which gain speed as they enter the mainland,” says Suhrid Sarkar, a meteorologist conducting a study on the changing nature of cyclones in Gangetic Bengal. His research shows that the mangrove shield is capable of bringing down the speed of cyclones like Cidar and Nargis from 240 kph to about 100 kph. Located south of the Tropic of Cancer and bounded by the northern limits of the Bay of Bengal, this forest is categorised as tropical moist forest raised by the deposition of sediment formed due to soil erosion in the Himalayas. The increase in salinity is killing trees faster than ever before. Those that manage to survive grow only very slowly. The phenomenon is called ‘top-dying’ and is related to sudden excess saline water creeping into the water table. The rot starts at the top and percolates downwards. ‘Case Studies on Climate Change and World Heritage’, a 2007 report by UNESCO, states that according to the Intergovernmental Panel on Climate Change an anthropogenic 45 cm increase in sea level is likely by the end of the 21st century. This, combined with other forms of anthropogenic stress on the Sunderbans, could lead to the destruction of 75% of the Sunderbans’ mangroves. What then is the solution? “Right now there is no better solution than to start a massive re-plantation programme,” says Biswajit Roychowdhury of Nature Environment and Wildlife Society, or NEWS. “As the trees get killed or their growth is arrested, a huge and sustained re-plantation drive is necessary to make up for what is lost.” Over the last two years, NEWS has been conducting a mangrove plantation and re-habitation workshop in five Sunderbans villages: Sonagaan, Dulki, Mathurakhand, Amlamethi and Tridibnagar. Funded first by the British High Commission and later by the Royal Bank of Scotland, the Rs 1.2 crore project missed its deadline because of Cyclone Aila. Around 20% of trees that were planted were destroyed in the storm and by local relief workers trampling over the saplings as they walked. “No drive can be a success without the involvement of local people,” says Roychowdhury. “It is they who are responsible for maintaining and propagating a system that we have started here.” The women of Jhorkhali and Gosaba actively participate in the plantation drive. Waking up to the impending disaster that the gradual extinction of their forest is likely to bring about, they plant and look after the mangrove saplings with utmost care. After about three months of being nurtured in a nursery, the saplings are ready to be planted. Experience has told local people that the crisis is more serious than meets the eye. Livelihood in the Sunderbans depends on two main occupations: fishing and honey-collection. Extensive salination is also causing fish patterns to change in the rivers of the Sunderbans. Commercially viable fish species like bhetki and parshe are being replaced by Bombay duck and amodi. If the trend continues, fishing could cease to be a viable livelihood option here.  “Limited awareness among the fishermen has rendered the soil unsuitable for mangrove plantation,” says Samir Basak, a local environmental activist. “Take prawn seed collection, for instance. As women collect the seeds, they dump the waste along the embankments, adding over 100 tonnes of waste to the soil every month. This heavy wasteload causes alarming loss of marine biodiversity, destroying the marine ecological balance.” Although he and his team are trying to increase awareness through workshops, Basak admits that no amount of persuasion works when it’s an issue involving earning one’s daily bread. Incidentally, human beings and mangrove forests are not the only species affected by the increased salinity in the rivers and soil of the Sunderbans. Naturalists point to countless instances of gradual fauna extinction as water salinity crosses tolerance levels. Much has been said about the threat faced by the Royal Bengal tiger. But the list has become longer with time to include the Javan rhino, water buffalo, swamp deer, barking deer and Batagur baska, a river terrapin that became extinct both in Indian and Bangladeshi forest areas. “What we need is a joint action plan with the government of Bangladesh,” says the director of the Sunderbans Biosphere Reserve, N C Bahuguna. “With this huge forest stretch spanning two countries, no one can expect to work in isolation.” Be that as it may, the Sunderbans mangrove forests require immediate attention by all thinking minds. The area was declared a reserve forest in 1875 and a UNESCO World Heritage Site in 1997. Ten years down the line it is shedding saline tears. (Ranit Mukherji was appointed Indian media specialist by the European Institute of Asian Studies for its EU-India Ethics in Media Exchange Programme. At present he is with Prasar Bharati, Broadcasting Corporation of India) Infochange News & Features, August 2009 |
