A combination of rising sea levels, intensified coastal erosion and human interventions is wreaking havoc along the Digha-Mandarmoni-Dadanpatrabar coastline, a stretch renowned for its scenic beauty and vibrant tourism. Recent studies have revealed alarming trends that pose significant threats to the region’s ecology, economy, and livelihood.

Data collected over the past 30 years shows a dramatic rise in sea levels along the Digha- Dadanpatrabar stretch, particularly during the monsoon, where levels have surged by a few meters. The annual mean sea level increase is measured at 3.4 mm per year, exceeding the global average of 3 mm.

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“This rise is partly driven by rapid climate change and the increasing frequency of cyclones, which bring storm surges that exacerbate coastal erosion,” explained Dr Ashis Kumar Paul, a geomorphologist from Vidyasagar University.

Additionally, land subsidence at an annual rate of 4 mm has compounded the sea level rise, effectively elevating it to 7.4 mm per year in the region, a figure Dr Paul describes as “alarmingly high.”

Erosion is rapidly altering the region’s coastline. Satellite imagery from 1992 to 2022 reveals long-term shoreline changes at Digha beach, which is eroding at an average rate of − 0.54 meters per year. The CRZ-II zone, in particular, has experienced severe erosion at a rate of −7.47 metres per year, while some areas show accretion rates as high as 8.55 metres per year.

Beaches along the stretch are narrowing, with Jhamra-Shyampur losing 3 metres per year, Shankarpur 2.5 metres, and Chandpur-Jaldah 2 metres. Although areas like Mandarmoni, Tajpur, and Gangadharpur have shown resilience due to protective vegetation, overall beach physiography is deteriorating.

Dr Paul highlighted three primary drivers of erosion. First one is climate change. Rising sea temperatures are increasing the intensity of cyclones, which generate higher waves and stronger storm surges that erode the shoreline. The second is sea level rise and subsidence. The combined impact of global sea level rise and local land subsidence is accelerating the retreat of the coastline. The last one is reduced silt deposition. Rivers such as Hooghly, Subarnarekha and Rasulpur, which previously deposited silt to protect the shoreline, now carry reduced loads due to human-controlled discharge patterns.

“The lack of silt deposition weakens the natural defenses against erosion, leaving the coastline more vulnerable,” Dr Paul noted.

The erosion crisis threatens the region’s booming beach tourism industry, particularly at Mandarmoni, a popular resort destination. As beaches narrow and infrastructure remains vulnerable to high waves, tourism revenue is at risk of significant decline.

Efforts to mitigate the crisis face additional hurdles due to widespread violations of Coastal Regulation Zone (CRZ) norms. The CRZ Act, first introduced in 1999 and enforced stringently in 2011, prohibits construction within 100 metres of the high tide line. However, many hotels and restaurants along the Digha-Mandarmoni stretch have been built in violation of these guidelines.

“Unchecked construction has not only increased vulnerability to erosion but also hampered natural processes that protect the coast,” said an official from the State Coastal Management Authority.

The challenges faced by the Digha-Mandarmoni coastline were highlighted at the COP29 Climate Change Conference. World leaders pledged to address coastal vulnerabilities globally, announcing the establishment of an adaptation fund to support affected regions.

Experts and environmentalists are urging immediate action. Dr Paul stressed the need for stricter enforcement of CRZ regulations and sustainable coastal management practices. “We must control the drivers of erosion and plan for sustainable tourism if we are to preserve the Digha-Mandarmoni coastline,” he said.