Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios
The densely populated delta of the three river systems of the Ganges, Brahmaputra and Meghna is highly prone to floods. Potential climate change-related increases in flood intensity are therefore of major societal concern as more than 40 million people live in flood-prone areas in downstream Banglad...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2022-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/ac8ca1 |
| _version_ | 1797747333500239872 |
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| author | Anne Gädeke Michel Wortmann Christoph Menz AKM Saiful Islam Muhammad Masood Valentina Krysanova Stefan Lange Fred Fokko Hattermann |
| author_facet | Anne Gädeke Michel Wortmann Christoph Menz AKM Saiful Islam Muhammad Masood Valentina Krysanova Stefan Lange Fred Fokko Hattermann |
| author_sort | Anne Gädeke |
| collection | DOAJ |
| description | The densely populated delta of the three river systems of the Ganges, Brahmaputra and Meghna is highly prone to floods. Potential climate change-related increases in flood intensity are therefore of major societal concern as more than 40 million people live in flood-prone areas in downstream Bangladesh. Here we report on new flood projections using a hydrological model forced by bias-adjusted ensembles of the latest-generation global climate models of CMIP6 (SSP5-8.5/SSP1-2.6) in comparison to CMIP5 (RCP8.5/RCP2.6). Results suggest increases in peak flow magnitude of 36% (16%) on average under SSP5-8.5 (SSP1-2.6), compared to 60% (17%) under RCP8.5 (RCP2.6) by 2070–2099 relative to 1971–2000. Under RCP8.5/SSP5-8.5 (2070–2099), the largest increase in flood risk is projected for the Ganges watershed, where higher flood peaks become the ‘new norm’ as early as mid-2030 implying a relatively short time window for adaptation. In the Brahmaputra and Meghna rivers, the climate impact signal on peak flow emerges after 2070 (CMIP5 and CMIP6 projections). Flood peak synchronization, when annual peak flow occurs simultaneously at (at least) two rivers leading to large flooding events within Bangladesh, show a consistent increase under both projections. While the variability across the ensemble remains high, the increases in flood magnitude are robust in the study basins. Our findings emphasize the need of stringent climate mitigation policies to reduce the climate change impact on peak flows (as presented using SSP1-2.6/RCP2.6) and to subsequently minimize adverse socioeconomic impacts and adaptation costs. Considering Bangladesh’s high overall vulnerability to climate change and its downstream location, synergies between climate change adaptation and mitigation and transboundary cooperation will need to be strengthened to improve overall climate resilience and achieve sustainable development. |
| first_indexed | 2024-03-12T15:50:12Z |
| format | Article |
| id | doaj.art-c196baf9323c417ba8f90ee923bb6d23 |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T15:50:12Z |
| publishDate | 2022-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-c196baf9323c417ba8f90ee923bb6d232023-08-09T15:16:23ZengIOP PublishingEnvironmental Research Letters1748-93262022-01-0117909403610.1088/1748-9326/ac8ca1Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenariosAnne Gädeke0https://orcid.org/0000-0003-0514-2908Michel Wortmann1https://orcid.org/0000-0002-1879-7674Christoph Menz2https://orcid.org/0000-0001-5127-1554AKM Saiful Islam3https://orcid.org/0000-0002-2435-8280Muhammad Masood4https://orcid.org/0000-0002-4627-1784Valentina Krysanova5https://orcid.org/0000-0002-9481-0148Stefan Lange6https://orcid.org/0000-0003-2102-8873Fred Fokko Hattermann7https://orcid.org/0000-0002-6046-4670Potsdam Institute for Climate Impact Research, Member of the Leibniz Association , Telegrafenberg, 14412 Potsdam, GermanyPotsdam Institute for Climate Impact Research, Member of the Leibniz Association , Telegrafenberg, 14412 Potsdam, Germany; School of Geography and the Environment, University of Oxford , South Parks Road, Oxford OX1 3QY, United KingdomPotsdam Institute for Climate Impact Research, Member of the Leibniz Association , Telegrafenberg, 14412 Potsdam, GermanyInstitute of Water and Flood Management, Bangladesh University of Engineering and Technology , Dhaka 1000, BangladeshBangladesh Water Development Board , Design Circle–9, Pani Bhaban (level-2), 72, Green Road, Dhaka 1215, BangladeshPotsdam Institute for Climate Impact Research, Member of the Leibniz Association , Telegrafenberg, 14412 Potsdam, GermanyPotsdam Institute for Climate Impact Research, Member of the Leibniz Association , Telegrafenberg, 14412 Potsdam, GermanyPotsdam Institute for Climate Impact Research, Member of the Leibniz Association , Telegrafenberg, 14412 Potsdam, GermanyThe densely populated delta of the three river systems of the Ganges, Brahmaputra and Meghna is highly prone to floods. Potential climate change-related increases in flood intensity are therefore of major societal concern as more than 40 million people live in flood-prone areas in downstream Bangladesh. Here we report on new flood projections using a hydrological model forced by bias-adjusted ensembles of the latest-generation global climate models of CMIP6 (SSP5-8.5/SSP1-2.6) in comparison to CMIP5 (RCP8.5/RCP2.6). Results suggest increases in peak flow magnitude of 36% (16%) on average under SSP5-8.5 (SSP1-2.6), compared to 60% (17%) under RCP8.5 (RCP2.6) by 2070–2099 relative to 1971–2000. Under RCP8.5/SSP5-8.5 (2070–2099), the largest increase in flood risk is projected for the Ganges watershed, where higher flood peaks become the ‘new norm’ as early as mid-2030 implying a relatively short time window for adaptation. In the Brahmaputra and Meghna rivers, the climate impact signal on peak flow emerges after 2070 (CMIP5 and CMIP6 projections). Flood peak synchronization, when annual peak flow occurs simultaneously at (at least) two rivers leading to large flooding events within Bangladesh, show a consistent increase under both projections. While the variability across the ensemble remains high, the increases in flood magnitude are robust in the study basins. Our findings emphasize the need of stringent climate mitigation policies to reduce the climate change impact on peak flows (as presented using SSP1-2.6/RCP2.6) and to subsequently minimize adverse socioeconomic impacts and adaptation costs. Considering Bangladesh’s high overall vulnerability to climate change and its downstream location, synergies between climate change adaptation and mitigation and transboundary cooperation will need to be strengthened to improve overall climate resilience and achieve sustainable development.https://doi.org/10.1088/1748-9326/ac8ca1floodsBangladeshCMIP6CMIP5ISIMIPtime of climate impact emergence |
| spellingShingle | Anne Gädeke Michel Wortmann Christoph Menz AKM Saiful Islam Muhammad Masood Valentina Krysanova Stefan Lange Fred Fokko Hattermann Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios Environmental Research Letters floods Bangladesh CMIP6 CMIP5 ISIMIP time of climate impact emergence |
| title | Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios |
| title_full | Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios |
| title_fullStr | Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios |
| title_full_unstemmed | Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios |
| title_short | Climate impact emergence and flood peak synchronization projections in the Ganges, Brahmaputra and Meghna basins under CMIP5 and CMIP6 scenarios |
| title_sort | climate impact emergence and flood peak synchronization projections in the ganges brahmaputra and meghna basins under cmip5 and cmip6 scenarios |
| topic | floods Bangladesh CMIP6 CMIP5 ISIMIP time of climate impact emergence |
| url | https://doi.org/10.1088/1748-9326/ac8ca1 |
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