Impacts of category 5 tropical cyclone Fantala (April 2016) on Farquhar Atoll, Seychelles Islands, Indian Ocean

Abstract : This paper provides newinsights on the impacts of a category 5 tropical cyclone on Indian Ocean atoll reef islands. Using multi-date aerial imagery and field observations, the contribution of tropical cyclone Fantala to shoreline and island change, and to sediment production and transport,was assessed on Farquhar Atoll, Seychelles Islands. Results showthat the twolargest islands (N3km2) only suffered limited land loss (−1.19 to−8.35%)while small islets lost 13.17 to 28.45% of their initial land area. Islands and islets exhibited contrasting responses depending on their location, topography and vegetation type. Depending on islands, the retreat of the vegetation line occurred either along all shorelines, or along ocean shoreline only. The structure (wooded vs. grassy) and origin (native vs. introduced) of the vegetation played a major role in island response. Five days after the cyclone, beach width and beach area were multiplied by 1.5 to 10, depending on the setting, and were interpreted as resulting from both sediment reworking and the supply of large amounts of fresh sediments by the reef outer slopes to the island system. Fourth months after the cyclone, extended sheets of loose sediments were still present on the reef flat and in inter-islet channels and shallow lagoon waters, indicating continuing sediment transfer to islands.
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https://hal.archives-ouvertes.fr/hal-01633439
Contributeur : Virginie Duvat <>
Soumis le : lundi 13 novembre 2017 - 08:51:07
Dernière modification le : lundi 4 juin 2018 - 16:50:02

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Virginie K.E. Duvat, Natacha Volto, Camille Salmon. Impacts of category 5 tropical cyclone Fantala (April 2016) on Farquhar Atoll, Seychelles Islands, Indian Ocean. Geomorphology, Elsevier, 2017, 298, pp.41 - 62. 〈https://authors.elsevier.com/a/1VrAQ,3sl3bVp2〉. 〈10.1016/j.geomorph.2017.09.022〉. 〈hal-01633439〉

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