Climate Change and Coastal Development: A Case of Sunderbans, India

Climate Change and Coastal Development: A Case of Sunderbans, India


Mayilvaganan M

Urbanisation, coupled with climate change, is leading to growing concerns about land use change and the loss of beneficial green ecosystem systems in the coastal zones globally. Human and environmental wellbeing is supported by resources such as the coastal forest ecosystem, water filtration, and flood mitigation. Nonetheless, maintaining these features in fragile eco-sensitive coastal zones requires the conservation and equitable distribution of mangrove near the coast where local inhabitants live.

Studies show that climate change is further expected to impact mangroves in small deltaic islands due to sea level rise and a foreseen increase in the frequency and severity of frequent cyclones, among other causes. Regardless of this, augmenting religious tourism to the Gangasagar Island in Sunderbans in the state of West Bengal in India is also very likely to pose a burden to the ecologically sensitive island. This analysis examines the impacts of climate change and coastal urban development changes on the patterns of land use, population surge, and loss of green space.

The Sunderbans delta that is about 360 km2 wide in the Bay of Bengal, created by the sediment deposits of three major rivers in the region—the Ganges, Brahmaputra and Meghna—is one of the world’s largest rich ecosystems with an area of dominant sundari species of mangroves and other species such as the Royal Bengal tiger, and Gangetic dolphins, etc.

About 40 percent of nearly 10,000 km2 of the Sundarbans mangrove forest, lies within West Bengal of India, while the rest 60 percent is in Bangladesh. It is entwined with numerous tidal rivers, estuaries and creeks. The extended freshwater swamps and their intertwined mangrove forests act as a natural buffer, protecting the mainland from cyclones, rising sea tides and other extreme natural events.

Gangasagar or Sagar Island, as it is called locally in Sunderbans, is just off the Bengal coast in the Hooghly estuary, on the point where River Ganga meets the Bay of Bengal. The physiographic features of Sagar Island consist of mud flats, salt marshes, sandy beaches and dunes and mangroves. With an area of 224.3 kms, Sagar Island has about 68 km broad shoreline. It is a fully inhabited island and as per the 2011 national census estimates, the island population at 212037. The island houses local population along with those migrated from nearby islands like Ghoramara, Lohachahara and Suparibhanga.

Shrinking Land Space and Green Cover

Mangrove forest cover in the Sunderbans is decreasing due to both anthropogenic and non-anthropogenic changes. The rising mean sea-level of about 2.6-4mm/yr has hastened the rate of coastal erosion, flooding and tidal creeks around the Sagar Island. Besides, an increased intensity of cyclonic storms has a cumulative effect on the loss of mangrove that traditionally gives green cover in the Sunderbans.

The Sagar Island that is built primarily in silt and clay has witnessed higher storm surges, shoreline change, and embankment breaching with high tidal erosion in the last few decades from both the sea as well as from the Muri Ganga and Hoogly River system. As a consequence of coastal erosion, the landforms in the coastal area of the Sagar Island are eroded considerably. Furthermore, the rising sea level and the intensity of cyclonic storms affects land loss, shrinking of the land and green space of the Island, along with the intrusion of salinity and contamination of fresh groundwater.

Reportedly, Sagar Island has shrunk by about 20 square miles since the mid-20th century while the annual rising sea level has not only caused livelihood stress on the island’s local population but also on the green cover. The green cover in the deltaic islands that are provided by the Mangroves are lost noticeably due to the rise in sea level as they flourish largely in the intertidal zone due to terrestrial space constraints with existing human structures and change in land uses pattern in the coastal zone.

Also, barrage stress, sediment erosion and increased salinity in mangrove habitat are other reasons for the above phenomena. Evidently, the ecologically fragile Sundarbans region in India and Bangladesh has lost 24.55 percent of the mangroves (136.77 square km) due to erosion, over the past three decades. The loss of the mangrove green cover has also impacted commercially sought-after fish species that are traditionally found with the ones that do not have as much market value.

Religious Tourism and the Coastal Development

Gangasagar Mela, an annual Hindu festival, attracts thousands of pilgrims from all over the country, who come to take a holy dip at the confluence of river Ganga and Bay of Bengal apart from offering their homage to the Kapil Muni temple (holy Sage), built about 200 years ago, on Makar Sankranti. While the tourist flow throughout the year is negligible, the influx of pilgrims between the months of January and early March every year has gone up considerably. This overshoot has led to many infrastructural development facilities to be built on the susceptible island. Dense swamp tree forest and mangroves have been destroyed to accommodate the growing needs of the infrastructural developments.

Even though the tourist inflow has generated the temporal benefit by generating jobs and income to the local community, it has intensified the destruction of Sagar ecology. The accumulation of organic and inorganic wastes, environment degradation apparently looks inevitable.

The Way Forward

The battle to preserve the green cover mangroves in the fragile deltaic island ecosystem is getting increasingly complicated. The increasingly polluting mega construction projects with climate that keep changing, bringing erratic and severe storms and erosions are relentlessly jeopardising the mangroves. A better understanding of climate change and policy intervention strategies relating to it, safeguarding the vulnerable the estuarine ecosystem are the needs of the hour.

Dr. Mayilvaganan M is Associate Professor, International Strategic and Security Studies Programme, National Institute of Advanced Studies, Bangalore. He can be reached at