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Affordable Coastal Protection in the Pacific Islands

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Affordable Coastal Protection in the Pacific Islands Affordable coastal protection in the Pacific islands DESKTOP REVIEW Tonkin + Taylor, in association with the University of New South Wales Water Research Laboratory (WRL), was engaged by the Pacific Region Infrastructure Facility (PRIF) to undertake an engineering study of affordable options for coastal protection. The objective is to build on existing knowledge in an effort to develop innovative solutions to protect coastlines in such a way that will maximise the use of local materials and labour while, at the same time, minimising the need for imported goods and equipment. This report not only catalogues the existing approaches to shoreline protection in the Pacific region, based on technical, social and environmental criteria; it also provides an evaluation of each. This report is published by PRIF, a multi-development partner coordination, technical assistance and research facility that supports infrastructure development in the Pacific. PRIF member agencies: Asian Development Bank (ADB), Australian Department of Foreign Affairs and Trade (DFAT), European Investment Bank (EIB), European Union (EU), Japan International Cooperation Agency (JICA), New Zealand Ministry of Foreign Affairs and Trade (NZMFAT), and the World Bank Group. The views expressed in this report are those of the authors and do not necessarily reflect the views and policies of ADB, its Board of Governors, the governments they represent, or any of the other PRIF member agencies. None of the above parties guarantees the accuracy of the data included in this publication or accepts responsibility for any consequence of their use. The use of information contained in this report is encouraged with appropriate acknowledgement. The report may only be reproduced with the permission of the PRIF Coordination Office. February 2017. More information and copies of this review can be obtained from: PRIF Coordination Office c/- Asian Development Bank Level 20, 45 Clarence Street Sydney, New South Wales, Australia, 2000 Email: [email protected] Phone: +61 2 8270 9444 Web: www.theprif.org Cover photo: ©World Bank. Photo by Lauren Day, building seawalls, Tarawa, Kiribati. Acknowledgements Acknowledgement is given to the following individuals and the organisations they represent for their contribution to the research: Name Organisation Yann Balouin BRGM, Orléans, France Jacqueline Bell Bioresearches Group Ltd., Auckland, New Zealand Sofia Bettencourt World Bank, Washington, DC, USA Stuart Bettington AECOM, Los Angeles, California, USA Chris Brown Chris Brown Consulting, Sacramento, California, USA Gillian Cambers Secretariat of the Pacific Community, Suva, Fiji Gildas Colleter Aurecon, Australia Nicolas Desramaut World Bank, Washington, DC, USA Siulai Fioana Elisala Tuvalu Alessio Giardino Deltares, Delft, The Netherlands Angus Gordon Coastal Zone Management and Planning Niels Holm-Nielsen World Bank, Washington, DC, USA Misti Hood TropSEA Engineering & Environmental, Queensland, Australia John Hughes Ministry of Infrastructure Development, Honiara, Soloman Islands Ian Iercet Public Works Department, Port Vila, Vanuatu Cliff Juillerat Ocean Caraibes—Coastal Environmental and Water Resources Engineers, Dominica Hugh Milliken Downer Group, Auckland, New Zealand Ken Munro Ministry of Infrastructure Development, Honiara, Soloman Islands Heather O’Keeffe GHD, USA Simon Restall International GeoSynthetic Society, Florida, USA Steven Sapalo World Bank, Washington, DC, USA Nick Smith McConnell Dowell, Victoria, Australia Helen Sykes Marine Ecology Consulting, Fiji Yusuke Taishi United Nations Development Programme, New York, USA Liz Watson Go Logistics (NZ) Ltd., Auckland, New Zealand In addition, thanks is given to the PRIF project team, comprising the Project Manager Lorena Estigarribia, Sanjivi Rajasingham, Oliver Whalley and Jack Whelan for their review, input and discussions relating to the project. Additional comments were provided by the PRIF Transport Sector Working Group and by the external reviewer, Doug Treloar of Cardno Emerging Markets (Australia) Pty. Ltd. Gratitude is also expressed to the authors of the review, Dr. Tom Shand from Tonkin + Taylor and James Carley from the University of New South Wales Water Research Laboratory, as well as to Margie Peters- Fawcett who copy edited the publication. Abbreviations ARI Annual Recurrence Interval BoM Bureau of Meteorology ENSO El Niño-Southern Oscillation km kilometre m3 Cubic metre MSL Mean sea level PIC Pacific island country PRIF Pacific Region Infrastructure Facility PVC Polyvinyl chloride ii Affordable coastal protection in the Pacific islands DESKTOP REVIEW Table of Contents 1 Introduction...........................................................................................................................................................1 1.1 Background and study objective..................................................................................................................................1 1.2 Scope of works ...................................................................................................................................................................2 1.3 Report outline ....................................................................................................................................................................2 2 Pacific environmental context .............................................................................................................................3 2.1 Introduction ........................................................................................................................................................................3 2.2 Geology .................................................................................................................................................................................4 2.3 Climate ..................................................................................................................................................................................6 2.3.1 Tropical cyclones .................................................................................................................................................7 2.4 Water levels .........................................................................................................................................................................8 2.4.1 Mean water levels ...............................................................................................................................................8 2.4.2 Tides ........................................................................................................................................................................9 2.4.3 Storm surge ........................................................................................................................................................10 2.4.4 Sea level rise......................................................................................................................................................11 2.5 Waves .................................................................................................................................................................................13 2.6 Reef-top processes ........................................................................................................................................................13 2.7 Sediment transport .......................................................................................................................................................14 2.8 Shoreline processes ......................................................................................................................................................15 3 Coastal protection in Pacific island countries .................................................................................................16 3.1 Introduction .....................................................................................................................................................................16 3.2 Alternatives to hard protection .................................................................................................................................18 3.2.1 Avoidance of or retreat from hazard .........................................................................................................18 3.2.2 Maintaining sediment budgets ...................................................................................................................18 3.2.3 Ecological-based approaches ......................................................................................................................18 3.3 Coastal protection structures ...................................................................................................................................19 3.3.1 Structural type ..................................................................................................................................................20 3.3.2 Failure mechanisms .......................................................................................................................................22 3.3.3 Effects of seawalls on beaches ..................................................................................................................23 3.4 Overview of coastal protection in Pacific island countries .............................................................................24
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