Coastal protection structures in Tarawa Atoll, Republic of Kiribati

In the context of rapid population growth and urbanization, atoll countries have engaged in reclamation works and in the construction of coastal defences to extend inhabitable areas and reduce the threats posed by coastal erosion and flooding. Despite their major role in asset protection, coastal structures are still poorly documented. However, a better knowledge of the characteristics of these structures (location, type, condition, management status, etc.) would facilitate the establishment of consistent construction and maintenance programmes, and also contribute to a better understanding of shoreline changes. To address this need, this paper provides an assessment of coastal structures on Tarawa Atoll in Kiribati. The results highlight the abundance of structures, mostly seawalls (94.7 % of the total), which stretch along 29 % of the coastline. The protected shoreline decreases from urban (53.9 % at Bairiki) to rural islands (27.3 % at Buota), in proportion to population pressure. The occurrence and height of structures are greater on windward, ocean shores than on lagoon shores. Seawall condition is better in rural islands, compared to urban and semi-urban areas. The observed differences in the characteristics and physical condition of coastal structures mainly reflect differences in the management status of structures and the availability of building materials and funding. More generally, the occurrence and characteristics of coastal structures are strongly correlated to population densities, land-use dynamics and shoreline mobility. At some locations, the failure of coastal protection highlights the seriousness of the problems raised by land-use practices in Tarawa.