Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 829, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2022.154547
Keywords
Ganges-Brahmaputra-Meghna delta; Anthropogenic climate change; Relative sea-level rise; Sedimentation; Sustainability
Categories
Funding
- 'ESPA Deltas' by ESPA programme - Department for International Development (DfID) [NE/J002755/1]
- Economic and Social Research Council (ESRC)
- Natural Environment Research Council (NERC), UK
- National Water Resources Database
- DECCMA Project part of the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA) [IDRC 107642]
- UK Government's DfID
- International Development Research Centre (IDRC), Canada
- WARPO
- MoWR, GoB
- ACCORD project - UK NERC (through National Oceanographic Center, NOC) [NE/R000123/1]
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The research examines the sedimentation and sustainable development of the Ganges-Brahmaputra-Meghna (GBM) delta. The study finds that under quasi-natural conditions, sedimentation can exceed the current rates of relative sea-level rise and potentially create new land mass. Encouraging quasi-natural conditions through the widespread application of sediment management measures has the potential to promote more sustainable outcomes for the GBM delta.
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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