TY - JOUR

T1 - Hydrodynamic Drivers and Morphological Responses on Small Coral Islands—The Thoondu Spit on Fuvahmulah, the Maldives

AU - David, C.G.

AU - Schlurmann, T.

N1 - Funding information: This study took place in the project Dealing with change in SIDS: societal action and political reaction in sea level change adaptation in Small Island Developing States (DICES), grant no. SCHL 503/17-1. The project was framed within the priority program (SPP 1889) ‘Regional Sea Level Change and Society’ (SeaLevel, see www.spp-sealevel.de) of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG). The publication of this article was funded by the Open Access fund of Leibniz Universität Hannover. The authors would like to thank Ali Ahmed, Pablo Ballesteros, Tatiana Ivanova, René Klein, Nina Kohl, Manò Schütt, Ibrahim Shiyan (Panda), Zahid as well as Marion, and Uwe Zander for their help in the field campaigns. On the Maldives, the authors were supported by the Maldives Meteorological Service (MMS), Fuvahmulah Island Council, and Fuvahmulah DIVE School. The authors would like to thank Ali Ahmed, Pablo Ballesteros, Tatiana Ivanova, Ren? Klein, Nina Kohl, Man? Sch?tt, Ibrahim Shiyan (Panda), Zahid as well as Marion, and Uwe Zander for their help in the field campaigns. On the Maldives, the authors were supported by the Maldives Meteorological Service (MMS), Fuvahmulah Island Council, and Fuvahmulah DIVE School. The authors further appreciate the involvement of the working group of Maike Paul for reviewing the manuscript. We further acknowledge the working group of Jan Visscher, Rik Gijsman, as well as our project members in DICES Susann Adloff, Arne Henning, Beate Ratter, and Katrin Rehdanz for their professional input. Additionally the authors thank Volker Roeber and Jannek Gundlach for their feedback concerning numerical models as well as Jean Bidlot, Mark Hemer, and Todd Spindler for their help in accessing climate reanalysis data. Also, Elisa Casella and Alessio Rovere gave valuable insights and feedback to UAV-based photogrammetry, while Tobias Kersten helped with geodetic questions before the third field campaign and while post-processing. Funding. This study took place in the project Dealing with change in SIDS: societal action and political reaction in sea level change adaptation in Small Island Developing States (DICES), grant no. SCHL 503/17-1. The project was framed within the priority program (SPP 1889) ?Regional Sea Level Change and Society? (SeaLevel, see www.spp-sealevel.de) of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG). The publication of this article was funded by the Open Access fund of Leibniz Universit?t Hannover.

PY - 2020/10/29

Y1 - 2020/10/29

N2 - Assessing the resilience of islands toward altered ocean climate pressures and providing robust adaptation measures requires an understanding of the interaction between morphological processes and the underlying hydrodynamic drivers. In this sense, this study presents changing sediment volumes on various temporal scales for the fringing reef island Fuvahmulah. Based on three field campaigns, conducted over 2 years, aerial imagery provides information on marine aggregates of the island's beaches. In addition, high resolution climate reanalysis data serves as input into an empirical and a numerical approach. Together, both approaches describe the driving processes behind volumetric seasonal and interannual changes: On the one hand, the empirical method quantifies sediment transport rates for calcareous sediments over the whole time span of the data set by considering wind and swell waves from multiple directions. On the other hand, the numerical method gives insights into the complexity of currents induced by dominant wave components. Combining these methods facilitates hindcasting and predicting morphological changes under varying wave climate, assessing sediment pathways over the whole reef, and describing the seasonal and interannual evolution of the sand spit Thoondu. As a result, this study reveals sediment distribution on different spatio-temporal scales and elucidates their significance in the design of conventional and alternative low-regret coastal adaptation.

AB - Assessing the resilience of islands toward altered ocean climate pressures and providing robust adaptation measures requires an understanding of the interaction between morphological processes and the underlying hydrodynamic drivers. In this sense, this study presents changing sediment volumes on various temporal scales for the fringing reef island Fuvahmulah. Based on three field campaigns, conducted over 2 years, aerial imagery provides information on marine aggregates of the island's beaches. In addition, high resolution climate reanalysis data serves as input into an empirical and a numerical approach. Together, both approaches describe the driving processes behind volumetric seasonal and interannual changes: On the one hand, the empirical method quantifies sediment transport rates for calcareous sediments over the whole time span of the data set by considering wind and swell waves from multiple directions. On the other hand, the numerical method gives insights into the complexity of currents induced by dominant wave components. Combining these methods facilitates hindcasting and predicting morphological changes under varying wave climate, assessing sediment pathways over the whole reef, and describing the seasonal and interannual evolution of the sand spit Thoondu. As a result, this study reveals sediment distribution on different spatio-temporal scales and elucidates their significance in the design of conventional and alternative low-regret coastal adaptation.

KW - climate change adaptation

KW - coastal management

KW - coral reefs

KW - global climate data

KW - low-lying islands

KW - Maldives

KW - morphology

KW - sand spit

KW - climate change adaptation

KW - coastal management

KW - coral reefs

KW - global climate data

KW - low-lying islands

KW - Maldives

KW - morphology

KW - sand spit

UR - http://www.scopus.com/inward/record.url?scp=85095988626&partnerID=8YFLogxK

U2 - 10.3389/fmars.2020.538675

DO - 10.3389/fmars.2020.538675

M3 - Article

VL - 7

JO - Frontiers in Marine Science

JF - Frontiers in Marine Science

SN - 2296-7745

M1 - 538675

ER -