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Sustainability of the coastal zone of the Ganges-Brahmaputra-Meghna delta under climatic and anthropogenic stresses

Sustainability of the coastal zone of the Ganges-Brahmaputra-Meghna delta under climatic and anthropogenic stresses
Sustainability of the coastal zone of the Ganges-Brahmaputra-Meghna delta under climatic and anthropogenic stresses
The Ganges-Brahmaputra-Meghna (GBM) delta is one of the world's largest deltas. It is currently experiencing high rates of relative sea-level rise of about 5 mm/year, reflecting anthropogenic climate change and land subsidence. This is expected to accelerate further through the 21st Century, so there are concerns that the GBM delta will be progressively submerged. In this context, a core question is: can sedimentation on the delta surface maintain its elevation relative to sea level? This research seeks to answer this question by applying a two-dimensional flow and morphological model which is capable of handling dynamic interactions between the river and floodplain systems and simulating floodplain sedimentation under different flow-sediment regimes and anthropogenic interventions. We find that across a range of flood frequencies and adaptation scenarios (including the natural polder-free state), the retained volume of sediment varies between 22% and 50% of the corresponding sediment input. This translates to average rates of sedimentation on the delta surface of 5.5 mm/yr to 7.5 mm/yr. Hence, under present conditions, sedimentation associated with quasi-natural conditions can exceed current rates of relative sea-level rise and potentially create new land mass. These findings highlight that encouraging quasi-natural conditions through the widespread application of active sediment management measures has the potential to promote more sustainable outcomes for the GBM delta. Practical measures to promote include tidal river management, and appropriate combinations of cross-dams, bandal-like structures, and dredging.
Anthropogenic climate change, Ganges-Brahmaputra-Meghna delta, Relative sea-level rise, Sedimentation, Sustainability
0048-9697
Rahman, Munsur
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Haque, Anisul
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Nicholls, Robert J.
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Darby, Stephen
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Urmi, Mahmida Tul
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Dustegir, Maruf
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Dunn, Frances
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Tahsin, Anika
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Razzaque, Sadmina
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Horsburgh, Kevin
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Talukder, Md Aminul Haque
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Rahman, Munsur
dfaeee62-6d84-443b-8362-fabf05517b51
Haque, Anisul
0d47d8f2-0195-4385-99d8-b91ec9387811
Nicholls, Robert J.
903cd62d-0d6d-4150-8e73-35dfe20f1aaf
Darby, Stephen
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Urmi, Mahmida Tul
405d4caa-cf5e-4259-bb54-68a2b43757cd
Dustegir, Maruf
2451b8b0-328b-4243-b0fc-42c3f821a212
Dunn, Frances
43ad074b-3134-4fc9-8c42-b330ee590f98
Tahsin, Anika
75cd8d66-93a4-4576-8750-1de83f235811
Razzaque, Sadmina
f6d73da7-3f84-451e-91be-fa54334b18c9
Horsburgh, Kevin
ae10571e-7441-4cfa-b44d-e8fa7bce7cce
Talukder, Md Aminul Haque
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Rahman, Munsur, Haque, Anisul, Nicholls, Robert J., Darby, Stephen, Urmi, Mahmida Tul, Dustegir, Maruf, Dunn, Frances, Tahsin, Anika, Razzaque, Sadmina, Horsburgh, Kevin and Talukder, Md Aminul Haque (2022) Sustainability of the coastal zone of the Ganges-Brahmaputra-Meghna delta under climatic and anthropogenic stresses. Science of the Total Environment, 829, [154547]. (doi:10.1016/j.scitotenv.2022.154547).

Record type: Article

Abstract

The Ganges-Brahmaputra-Meghna (GBM) delta is one of the world's largest deltas. It is currently experiencing high rates of relative sea-level rise of about 5 mm/year, reflecting anthropogenic climate change and land subsidence. This is expected to accelerate further through the 21st Century, so there are concerns that the GBM delta will be progressively submerged. In this context, a core question is: can sedimentation on the delta surface maintain its elevation relative to sea level? This research seeks to answer this question by applying a two-dimensional flow and morphological model which is capable of handling dynamic interactions between the river and floodplain systems and simulating floodplain sedimentation under different flow-sediment regimes and anthropogenic interventions. We find that across a range of flood frequencies and adaptation scenarios (including the natural polder-free state), the retained volume of sediment varies between 22% and 50% of the corresponding sediment input. This translates to average rates of sedimentation on the delta surface of 5.5 mm/yr to 7.5 mm/yr. Hence, under present conditions, sedimentation associated with quasi-natural conditions can exceed current rates of relative sea-level rise and potentially create new land mass. These findings highlight that encouraging quasi-natural conditions through the widespread application of active sediment management measures has the potential to promote more sustainable outcomes for the GBM delta. Practical measures to promote include tidal river management, and appropriate combinations of cross-dams, bandal-like structures, and dredging.

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Accepted/In Press date: 9 March 2022
e-pub ahead of print date: 15 March 2022
Published date: 10 July 2022
Additional Information: Funding Information: Collecting the bathymetry data was supported by the ‘ESPA Deltas (NE/J002755/1)’ project supported by the ESPA programme, funded by the Department for International Development (DfID), the Economic and Social Research Council (ESRC) and the Natural Environment Research Council (NERC), UK, and the National Water Resources Database hosted at Water Resources Planning Organization (WARPO), Ministry of Water Resources (MoWR), Government of the People's Republic of Bangladesh (GoB). The model development was supported by the DECCMA Project (Grant No. IDRC 107642 ), part of the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA), with financial support from the UK Government 's DfID and the International Development Research Centre (IDRC), Canada, the WARPO Projects, ‘Research on the Morphological processes under Climate Changes, Sea Level Rise and Anthropogenic Intervention in the coastal zone’ and ‘Research on Sediment Distribution and Management in South-West Region of Bangladesh’ funded from MoWR, GoB and the ACCORD project ( NE/R000123/1 ) funded by the UK NERC (through National Oceanographic Center, NOC). Publisher Copyright: © 2022 Elsevier B.V.
Keywords: Anthropogenic climate change, Ganges-Brahmaputra-Meghna delta, Relative sea-level rise, Sedimentation, Sustainability

Identifiers

Local EPrints ID: 456343
URI: http://eprints.soton.ac.uk/id/eprint/456343
ISSN: 0048-9697
PURE UUID: 703df1cb-0514-4ec5-8963-cea45e9ce144
ORCID for Stephen Darby: ORCID iD orcid.org/0000-0001-8778-4394
ORCID for Frances Dunn: ORCID iD orcid.org/0000-0003-3726-7158

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Date deposited: 27 Apr 2022 02:24
Last modified: 23 Mar 2024 05:01

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Contributors

Author: Munsur Rahman
Author: Anisul Haque
Author: Robert J. Nicholls
Author: Stephen Darby ORCID iD
Author: Mahmida Tul Urmi
Author: Maruf Dustegir
Author: Frances Dunn ORCID iD
Author: Anika Tahsin
Author: Sadmina Razzaque
Author: Kevin Horsburgh
Author: Md Aminul Haque Talukder

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