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Exposure of atoll population to coastal erosion and flooding: a South Tarawa assessment, Kiribati

Abstract

Atoll countries are particularly vulnerable to coastal hazards in the context of global change, which justifies the interest in population exposure assessments. This paper contributes to addressing this need by assessing the current exposure of the population of two areas of the South Tarawa Urban District (Tarawa Atoll, Republic of Kiribati) to coastal erosion and flooding. The assessment is based on data relating to island morphology (digital terrain models and shoreline change), land use (building extension and coastal works) and environmental changes reconstructed for the 1969–2008 period. The results highlight rapid changes in land use and significant differences in current population exposure to coastal erosion and flooding between and within study sites. Between 1969 and 2007–2008, the built area located less than 20 m from the reference shoreline has increased by a factor of 4.2 at Bairiki and by a factor of 32.2 at Eita–Bangantebure, enhancing population exposure given that land elevation is low (12.6 and 77.4 % <2 m at Bairiki and Eita–Bangantebure, respectively). Nevertheless, in Bairiki, 87.5 % of the built area is currently not exposed to coastal erosion (>20 m from the coastline) and flooding (>1.5 m). Building exposure is higher at Eita–Bangantebure, where 71.3 % of the built area is currently not exposed (using the same criteria), but 17.1 % shows medium to very high levels of exposure, due to very low land elevation (22.3 % of the land area <1.5 m) and shoreline recession. The Eita–Bangantebure case study exemplifies the maladaptive trajectories of change that have been reported in other atoll countries.

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Notes

  1. 1.

    In official censuses, the week previous to the survey date is the reference point for describing a person's employment situation (What work did this person do last week and was it a paid job?).

  2. 2.

    The Government of Kiribati distinguishes these three housing types in national statistics.

  3. 3.

    “Common house”, public building.

  4. 4.

    The Nippon causeway connecting Bairiki and Betio is the most recent example. It was completed in 1987.

  5. 5.

    Buildings more than 3 m high represent only 2.0 % of the total number of buildings and 1.9 % of the total built area, and so we grouped them with buildings between 2 and 2.5 m high, and between 2.5 and 3 m high.

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Acknowledgments

First, the authors thank the Permanent Secretary of the Ministry of Fisheries and Marine Resources Development for granting the research permit for this study. The Ministry generously provided the aerial photographs without which this work would not have been completed. We address our very special thanks to Kabure Yeeting, Naomi Biribo and Romano Reo. Thanks to Amon Timan for interesting discussions on recent changes in South Tarawa and to Ueantabo Neemia MacKenzie (USP) for talks on coastal risks and social capital. Thanks to the many residents met on the coast who kindly agreed to answer our questions. Warm thanks to Arthur Webb (SOPAC) for interesting discussions about the South Tarawa situation. Thanks to Fabrice Lartigou (2D3DGIS) for giving us very helpful information before our first visit in Kiribati. This work was supported by the CNRS, the University of la Rochelle and the French National Research Agency (ANR). At LIENSs, special thanks to Cécilia Pignon-Mussaud and Dorothée James for the setting up of the GeoKiribati GIS, and to Camille Salmon for further work, particularly on the digitization of buildings. Great thanks to Pascal Brunello for help in finalizing maps. Last but not least, warm thanks to the anonymous reviewers and the editors for their helpful comments that improved this paper, and to James Johnson for his valuable support in English editing.

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Correspondence to Virginie Duvat.

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Handled by Donald L. Forbes, Geological Survey of Canada/Natural Resources Canada, Canada.

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Duvat, V., Magnan, A. & Pouget, F. Exposure of atoll population to coastal erosion and flooding: a South Tarawa assessment, Kiribati. Sustain Sci 8, 423–440 (2013). https://doi.org/10.1007/s11625-013-0215-7

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Keywords

  • Population exposure
  • Coastal erosion
  • Flooding
  • SIDS
  • Kiribati
  • Trajectories of change