Author: Jyotirindra Narayan Lahiri/ Photographs: Abhijit Chakraborty
Within a very short period, two big cyclones, Bulbul and Amphan, absolutely pulverized a large chunk of the Indian part of Sunderbans. These have left a trail of devastation all around and have made a long-lasting impression on the river dams of the region. Though a cliché, the phrase “river dams are the lifeline for the Sunderbans” is still relevant. These earthen dams are used as shields to protect the human settlements from the hungry tidal waves.
The 3.5 million people who live in this archipelago, started coming to this part during the British period. The English masters brought a decent population to this region and made them settle down here by cleaning up the adjoining vegetation and cultivate lands. Their sole purpose was to collect revenue, even from the mangrove area. Thus went on a century-long land acquisition episode which is far from being over even now. It is not possible to cultivate lands once the tidal waters enter there every high tide, so the plan is to enclose the entire land with dams to prevent saline waters from entering.
These dams, built almost 200 years ago, have undergone many changes in these two centuries, but their necessity and importance remain the same. Even now, when a super cyclone like Amphan hits the island, the dams erode and break down due to the current and the saline water that gushes into the island. This sort of incidents not only happens during Aila, Bulbul, Amphan.
If we visit various settlements across the Sunderbans during the monsoon, we can almost hear people expressing concern over the longevity of the dams. Only when heavy downpours occur here and quite a large amount of people fall into hapless condition, does the media cover the issues of this region.
During the Aila destruction of 2009, dams were damaged in a large part of the Indian Sundarbans. About 700 km of river dams were destroyed during the calamity. Further hundreds of kilometres of river dams were severely damaged. Constructions of dams were started by various initiatives of Central and State government afterwards. Unfortunately, even after eleven years, reconstruction work has not been completed everywhere. A reason for it being the lack of land needed to construct the earthen dams.
Though geographically located in a very vulnerable zone, the islands adjacent to the Indian Sunderbans are densely populated. The official plan to construct dam after the Aila destruction had decided to keep the slope of the dam towards the embankment to a much lower degree (3:1) — hence the angle between the imaginary hypotenuse and the tip of the land was around 18.4 degree.
The main reason behind keeping the slope low was to push the tidal waters towards the seabed as much as possible so that the earthen dams could withstand the force with which the waters hit the walls of the dams. A large area of the landmass is needed to construct such dams. But the question why the construction of such dams has not yet been completed, even after a decade of the Aila destruction, still reverberates around the Sunderbans today.
A visit to the various villages to find the answer reveals that in most cases, the main reason is the inability to acquire lands officially. The common people of the region often got influenced by the views of the local political leaders (irrespective of any political party). The long-term solution may be a proper construction of a concrete dam, which can be an immediate remedy to this grave issue.
Another issue is that after the construction of these officially sanctioned dams, planting of mangroves on the riverside was made compulsory, but in most places, this work was not completed. The mangrove bed can protect dams from the initial push of water. Though at initial look, the mangrove cover seems not so effective yet its role cannot be denied. Recently, we came across many images showing the eroded conditions of the earthen dams at various places of the Sunderbans, all thanks to the media. However, we observed that wherever there’s no mangrove cover in front of the concrete dams, the damage has been most in those areas.
Notably, the construction of concrete dams was announced in those areas which were completely devastated by the Aila. Now the thing is a wide stretch of river dams remained next to these ‘earthen dams’ as a result. There is no guarantee that the next storm will only hit the newly constructed part of the concrete. Weak river dams cannot withstand the impact of a cyclone hitting the adjacent earthen dams.
Meanwhile, the monsoon season has started in the Sundarbans. Naturally, the water is rising in the river; the pressure on the dam is increasing. Sending relief for Amphan is not an immediate necessity now. Hurried attempts are being made now to somehow make the dams (or at least its skeleton) stand. The question remains as to how much pressure these dams will be able to withstand in the coming monsoon.
Though the dams built during the Aila episode didn’t suffer any noticeable damage in the recent Amphan devastation, a question remains. Will the construction of concrete dams everywhere done during Aila is a permanent solution? This isn’t that simple a matter. One thing that we must keep in mind is that Sunderbans is still a new landmass; the process of its formation is still going on.
The course of the river here is ever-changing; it is very common in the Sundarbans for the sudden rise of a huge landmass out of nowhere in a river or a very high rate of erosion on a particular side of a river.
A large part of the dam in Rangabelia village of Gosaba Block has been damaged due to the storm. If we take a good look at the map there, we can understand how the Vidya and Gomor rivers from both sides of the island have been trying to come closer with dangerous turns in the last few decades. The land between the two rivers is only two hundred and fifty meters. In this narrow part between Rangabelia and Bagbagan, the river Gomor can be seen on the east while standing on the bank of Vidya, which is situated on the west.
The bottom line is that tidal water has not been able to accumulate sediment in the islands that have been surrounded by dams for a long time. Most of these sediments, which were washed away by the tide during the tide, could not accumulate in the islands and got assimilated at the bottom of the river. As a result, the water pressure on the shallow river is increasing, generating heavy pressure on the dams. It should be clearly understood that the area which is called ‘intertidal space’ needs to be left alone for the flow of the river.
Looking at the real situation, we can see that it is impossible to acquire this amount of land to build dams in the densely populated Indian Sundarbans villages. We must drop this initiative for the river to flow naturally. The people of the Sundarbans have to face dangers again and again by constantly battling with nature. This settlement has to be maintained by proper coexistence with nature.