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Land raising as a solution to sea-level rise: an analysis of coastal flooding on an artificial island in the Maldives

Land raising as a solution to sea-level rise: an analysis of coastal flooding on an artificial island in the Maldives
Land raising as a solution to sea-level rise: an analysis of coastal flooding on an artificial island in the Maldives
The Maldives (land elevation approximately 1m above mean sea-level) is often associated with the threat of rising sea-levels. Land scarcity due to population pressure is also a major issue. In the late 1990s a new 1.9km2 2m high artificial island, Hulhumalé was created for urban expansion, including an allowance for sea-level rise. This paper assesses flood exposure through an extreme water level scenario on Hulhumalé taking into account sea-level rise and analyses potential adaptation options to extend island life.

Results indicate that overtopping is likely to occur with 0.6±0.2m of SLR, with more severe, widespread flooding with 0.9±0.2m of sea-level rise. If the Paris Agreement goals are met, flooding is not anticipated this century, but under a non-mitigation scenario, flooding could occur by the 2090s. Building seawalls 0.5m, 1.0m and 1.5m high could delay flooding for 0.2m, 0.4m and 0.6m of sea-level rise, respectively.

Land raising has been successful in Hulhumalé in reducing flood risk simultaneous to addressing development needs. Whilst new land claim and raising can be cost-effective, raising developed land provides greater challenges, such as timeliness with respect to infrastructure design lives or financial costs. Thus the transferability and long-term benefits of land raising requires further consideration.
adaptation, defence, flooding, island, land claim, sea-level rise
Brown, Sally
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Wadey, Matthew
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Nicholls, Robert
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Shareef, Ali
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Khaleel, Zammath
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Hinkel, Jochen
9c7e8026-955c-42cd-9179-6113efbf1339
Lincke, Daniel
8b279c5b-dd6e-46f4-9c8d-adf83f6ea2cd
McCabe, Maurice V.
682a275f-fee6-4dd1-8a99-1eda586f365d
Brown, Sally
dd3c5852-78cc-435a-9846-4f3f540f2840
Wadey, Matthew
e712b840-f36b-41aa-ae28-d4d81de31831
Nicholls, Robert
4ce1e355-cc5d-4702-8124-820932c57076
Shareef, Ali
87d79c30-9d8c-458b-95fd-4a8ea13e56c5
Khaleel, Zammath
0b06a7c3-28f0-4fc6-bb12-95b9d837f390
Hinkel, Jochen
9c7e8026-955c-42cd-9179-6113efbf1339
Lincke, Daniel
8b279c5b-dd6e-46f4-9c8d-adf83f6ea2cd
McCabe, Maurice V.
682a275f-fee6-4dd1-8a99-1eda586f365d

Brown, Sally, Wadey, Matthew, Nicholls, Robert, Shareef, Ali, Khaleel, Zammath, Hinkel, Jochen, Lincke, Daniel and McCabe, Maurice V. (2020) Land raising as a solution to sea-level rise: an analysis of coastal flooding on an artificial island in the Maldives. Journal of Flood Risk Management, 13 (S1), [e12567]. (doi:10.1111/jfr3.12567).

Record type: Article

Abstract

The Maldives (land elevation approximately 1m above mean sea-level) is often associated with the threat of rising sea-levels. Land scarcity due to population pressure is also a major issue. In the late 1990s a new 1.9km2 2m high artificial island, Hulhumalé was created for urban expansion, including an allowance for sea-level rise. This paper assesses flood exposure through an extreme water level scenario on Hulhumalé taking into account sea-level rise and analyses potential adaptation options to extend island life.

Results indicate that overtopping is likely to occur with 0.6±0.2m of SLR, with more severe, widespread flooding with 0.9±0.2m of sea-level rise. If the Paris Agreement goals are met, flooding is not anticipated this century, but under a non-mitigation scenario, flooding could occur by the 2090s. Building seawalls 0.5m, 1.0m and 1.5m high could delay flooding for 0.2m, 0.4m and 0.6m of sea-level rise, respectively.

Land raising has been successful in Hulhumalé in reducing flood risk simultaneous to addressing development needs. Whilst new land claim and raising can be cost-effective, raising developed land provides greater challenges, such as timeliness with respect to infrastructure design lives or financial costs. Thus the transferability and long-term benefits of land raising requires further consideration.

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Accepted/In Press date: 26 August 2019
e-pub ahead of print date: 9 September 2019
Published date: January 2020
Additional Information: Funding Information: is located in the Appendix A4 S.B., R.N., A.S., Z.K., J.H., and DL received funding from the European Union Seventh Framework Programme FP7/2007–2013 under grant agreement no. 282746 (IMPACT2C: Quantifying projected impacts under 2°C of warming). S.B., M.W., R.N., J.N., and D.L. received funding from the European Union Framework Programme through the grant of the budget of the Collaborative Project RISES‐AM‐, Contract ENV‐2013‐two‐stage‐603396. The authors are grateful to Land and Marine Environmental Resource Group (La Mer), Maldives for providing the bathymetry data used in this research, and to numerous students who helped in the early stages of the analysis of this data. Data for Figure . Data for other figures is not publically available due to commercial sensitivities. Sea‐level data was freely downloaded from the University of Hawaii Sea Level Centre ( http://uhslc.soest.hawaii.edu/ ) and WaveWatch III data from the NOAA/National Weather Service National Centers for Environmental Prediction Environmental Modelling Center Marine Modelling and Analysis Branch ( http://polar.ncep.noaa.gov/waves/download.shtml ). We thank Sandy Bisaro for help on land claim valuation. S.B. helped design the study, led the work, wrote the paper, and analysed the data. M.W. undertook the modelling and data analysis, assisted by M.M. M.W. and M.M. helped write the Appendix, with M.W. writing parts and creating figures of the manuscript taken from earlier project reports. R.N. helped design and co‐ordinate the study. A.S. and Z.K. set up the research problem, collated/commissioned the data and led the fieldwork. R.N., J.H., and D.L. helped with the study analysis and fieldwork. All authors commented on the manuscript text. Publisher Copyright: © 2019 The Authors. Journal of Flood Risk Management published by Chartered Institution of Water and Environmental Management and John Wiley & Sons Ltd.
Keywords: adaptation, defence, flooding, island, land claim, sea-level rise

Identifiers

Local EPrints ID: 433764
URI: http://eprints.soton.ac.uk/id/eprint/433764
PURE UUID: b91c1d6f-6d9e-4aa8-90fc-4391dbc206c2
ORCID for Sally Brown: ORCID iD orcid.org/0000-0003-1185-1962
ORCID for Robert Nicholls: ORCID iD orcid.org/0000-0002-9715-1109

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Date deposited: 03 Sep 2019 16:30
Last modified: 29 Jul 2022 04:01

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Contributors

Author: Sally Brown ORCID iD
Author: Matthew Wadey
Author: Robert Nicholls ORCID iD
Author: Ali Shareef
Author: Zammath Khaleel
Author: Jochen Hinkel
Author: Daniel Lincke
Author: Maurice V. McCabe

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