Changing coastline
The Sundarban islands have been shaped by the powerful forces of erosion and sedimentation over many years. But the coastline is now eroding quickly, threatened by both natural and human-induced processes. Rising sea levels, increased cyclones and reduced sediment flow from upstream are contributing factors. As a result, the delicate balance between land and water is disrupted, causing land loss and habitat degradation.
How has the coastline of Sundarbans changed over the years?
The change in the lay of the land—as seen through satellite images
Drag the slider to see how these 2 islands- Bhangaduani and Bulchery have lost their area since 1984
Vanishing islands
In the last 20 years, four islands—-Bedford, Lohachara, Kabasgadi, and Suparibhanga, have been permanently inundated. Ghoramara island is also rapidly vanishing. Here are the snapshots of the vanished islands from Google Maps.
Ghoramara island
88% of the island area has eroded. Currently it is 3 km², has a population of 4500 people currently.
Lohachara island
Completely inundated since 1980s, used to be inhabited. Most of the people have migrated to Sagar island.
Bedford island
Completely inundated. Since it was uninhabited, it did not directly affect the people.
Why the unnatural erosion?
We know that islands sink and form all the time in an estuarine dynamic system. But the rate at which sinking and erosion is happening in high What really caused this unnatural erosion?
Are there any anthropogenic (man-made) factors behind the phenomenon?
The islands' constant state of transformation has been disturbed by anthropogenic activities like—multiple dams and interventions on the Ganga, construction of guide walls near Haldia port in addition to sea level rise.
Incomplete Guidewalls
To solve shallow waters of the Haldia port so that ships could dock, and improvement of drought in Hugli estuary— 7 guide walls (concrete walls) had been suggested to the Kolkata Port Trust in 1980s.
Out of the 7, only 2 were constructed. The project was abandoned midway. This led to a disbalance. Nayachar island grew tremendously whereas Ghoramara and Lohachara eroded away.
Natural defence
Mangroves are a highly effective natural defence against cyclones and tidal surges. Reducing wind and wave impact, stabilizing shorelines, slowing down water and reducing energy of waves are its main functions apart from providing a marine ecosystem.
Unfortunately, mangrove coverage has drastically gone down in the Sundarbans. Human activities like deforestation, rising sea levels have also contributed to the decline of mangrove cover in the Sundarbans.
Up next, read how the sea is getting warmer and rising in level
Made with ♥ in IDC | Alivia Chaudhuri