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Devsena Roychaudhury

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Sea level rise effect on inhabited river-deltaic estuarine islands in the tropical monsoon regions in the Indian Sundarbans

Rituparna Acharyya, Niloy Pramanick, Rishin Basu Roy, Masuma Begum, Arjan Basu Roy, Devsena Roychaudhury, Anasua Pal, Anushka Chakraborty, Prasun Majumder

Geographia Polonica (2025) vol. 98, iss. 2, pp. 121-147
doi: https://doi.org/10.7163/GPol.0296

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Abstract

Coastal deltaic landscapes under tropical monsoon regions are sensitive to sea level changes exacerbated by human interventions. In low-lying areas, rising relative sea level (RSL) and such interventions are intensifying geohazards like coastal erosion and land subsidence. This study examines erosion and flooding risks in the Sundarbans mangroves along the Bay of Bengal using statistical models – Endpoint Rate (EPR) and Shoreline Change Envelope (SCE) incorporated in Digital Shoreline Analysis System (DSAS). “Patharpratima Block”comprises thirteen estuarine islands, part of the delta formed via confluence of three rivers, the Ganges, the Brahmaputra, and the Meghna. EPR and SCE were applied via geospatial modelling, and remote sensing to evaluate coastal changes between 1990-2020. Results show the shoreline undergoes gradual to significant changes due to fluctuating erosion and deposition, impacting local residents. Surendranagar and Dhanchiwere identified as the most vulnerable, followed by moderately vulnerable Lothian. With observed RSL rise, shoreline dynamics were modeled using EPR and SCE to estimate past and future changes. Additionally, the Sundarban Reserve Forest (SRF), the world’s largest mangrove forest, is at risk of disappearing. The region’s population has increased, while total area has shrunk due to erosion. Urgent sustainable measures are neededto prevent biodiversity loss and displacement of livelihoods into environmental refugees.

Keywords: sea level rise, river estuarine islands, shoreline, coastline, geospatial modeling, Patharpratima Block

Rituparna Acharyya [rituparna.acharyya@ukw.edu.pl], Faculty of Geographical Sciences Kazimierz Wielki University Plac Koscieleckich 8, 85-064 Bydgoszcz: Poland
Niloy Pramanick, School of Oceanographic Studies Jadavpur University Kolkata, West Bengal: India
Rishin Basu Roy, Department of Environmental Science University of Calcutta Kolkata, West Bengal: India
Masuma Begum, Directorate of Forests Government of West Bengal Kolkata, West Bengal: India
Arjan Basu Roy, Nature Mates-Nature Club Kolkata, West Bengal: India
Devsena Roychaudhury, Nature Mates-Nature Club Kolkata, West Bengal: India
Anasua Pal, Nature Mates-Nature Club Kolkata, West Bengal: India
Anushka Chakraborty, Nature Mates-Nature Club Kolkata, West Bengal: India
Prasun Majumder, Nature Mates-Nature Club Kolkata, West Bengal: India