Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream?

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Van Khanh Triet, Nguyen
dc.contributor.author Viet Dung, Nguyen
dc.contributor.author Fujii, Hideto
dc.contributor.author Kummu, Matti
dc.contributor.author Merz, Bruno
dc.contributor.author Apel, Heiko
dc.date.accessioned 2017-10-15T20:56:24Z
dc.date.available 2017-10-15T20:56:24Z
dc.date.issued 2017-08-07
dc.identifier.citation Van Khanh Triet , N , Viet Dung , N , Fujii , H , Kummu , M , Merz , B & Apel , H 2017 , ' Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream? ' Hydrology and Earth System Sciences , vol 21 , no. 8 , pp. 3991-4010 . DOI: 10.5194/hess-21-3991-2017 en
dc.identifier.issn 1027-5606
dc.identifier.issn 1607-7938
dc.identifier.other PURE UUID: d7749bbe-38f9-4f85-bb62-642a5a2790c5
dc.identifier.other PURE ITEMURL: https://research.aalto.fi/en/publications/has-dyke-development-in-the-vietnamese-mekong-delta-shifted-flood-hazard-downstream(d7749bbe-38f9-4f85-bb62-642a5a2790c5).html
dc.identifier.other PURE LINK: http://www.scopus.com/inward/record.url?scp=85027346513&partnerID=8YFLogxK
dc.identifier.other PURE FILEURL: https://research.aalto.fi/files/15226408/hess_21_3991_2017.pdf
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/28317
dc.description.abstract In the Vietnamese part of the Mekong Delta (VMD) the areas with three rice crops per year have been expanded rapidly during the last 15 years. Paddy-rice cultivation during the flood season has been made possible by implementing high-dyke flood defenses and flood control structures. However, there are widespread claims that the high-dyke system has increased water levels in downstream areas. Our study aims at resolving this issue by attributing observed changes in flood characteristics to high-dyke construction and other possible causes. Maximum water levels and duration above the flood alarm level are analysed for gradual trends and step changes at different discharge gauges. Strong and robust increasing trends of peak water levels and duration downstream of the high-dyke areas are found with a step change in 2000/2001, i.e. immediately after the disastrous flood which initiated the high-dyke development. These changes are in contrast to the negative trends detected at stations upstream of the high-dyke areas. This spatially different behaviour of changes in flood characteristics seems to support the public claims. To separate the impact of the high-dyke development from the impact of the other drivers - i.e. changes in the flood hydrograph entering the Mekong Delta, and changes in the tidal dynamics - hydraulic model simulations of the two recent large flood events in 2000 and 2011 are performed. The hydraulic model is run for a set of scenarios whereas the different drivers are interchanged. The simulations reveal that for the central VMD an increase of 9-13cm in flood peak and 15 days in duration can be attributed to high-dyke development. However, for this area the tidal dynamics have an even larger effect in the range of 19-32cm. However, the relative contributions of the three drivers of change vary in space across the delta. In summary, our study confirms the claims that the high-dyke development has raised the flood hazard downstream. However, it is not the only and not the most important driver of the observed changes. It has to be noted that changes in tidal levels caused by sea level rise in combination with the widely observed land subsidence and the temporal coincidence of high water levels and spring tides have even larger impacts. It is recommended to develop flood risk management strategies using the high-dyke areas as retention zones to mitigate the flood hazard downstream.. en
dc.format.extent 20
dc.format.extent 3991-4010
dc.format.mimetype application/pdf
dc.language.iso en en
dc.relation.ispartofseries Hydrology and Earth System Sciences en
dc.relation.ispartofseries Volume 21, issue 8 en
dc.rights openAccess en
dc.subject.other Water Science and Technology en
dc.subject.other Earth and Planetary Sciences (miscellaneous) en
dc.subject.other 218 Environmental engineering en
dc.title Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream? en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department Helmholtz Centre Potsdam - German Research Centre for Geosciences
dc.contributor.department Yamagata University
dc.contributor.department Department of Built Environment
dc.subject.keyword Water Science and Technology
dc.subject.keyword Earth and Planetary Sciences (miscellaneous)
dc.subject.keyword 218 Environmental engineering
dc.identifier.urn URN:NBN:fi:aalto-201710157177
dc.identifier.doi 10.5194/hess-21-3991-2017
dc.type.version publishedVersion

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