Shoreline changes of small atoll nation, Tuvalu: A brief review

Abstract

Tuvalu is a small country (26 km2) in the South-Western Pacific Ocean composed of nine widely scattered coral atolls and islands. Its land areas are highly vulnerable to changes due to many natural and some man-made causes. Very low height of its most of the land areas than the mean sea level as well as its location in a zone of high sea-level rise prediction in the Pacific Ocean made it vulnerable to coastal subsidence. It possesses very long coastline due to presence of many small but long and narrow islets of the atolls. The soil qualities of the coastal regions generally are poor due to high contents of calcareous sand. Moreover, it faces frequent tropical cyclones of which some strong cyclones have made drastic changes to its coastlines. Thus, in this study the coastline changes over a century were reviewed based on published documents. Most of the works were done on the capital islet Funafuti. The early studies were mainly done based on surveys, maps, historical images, etc. whereas the recent works are mainly done by using satellite images where the edge of vegetation was considered to study coastline changes in most cases. It is found that the Cyclone Bebe in 1972 caused formation of 118km rubble rampart and Cyclone Pam in 2015 caused 2.75ha sudden accretion of land though different areas of the islets faced accretion and erosion as well. However, lagoon basin dredging in 1990’s was supposed to accelerate coastal erosion, and afterwards no major changes due to anthropogenic activities were identified. In Funafuti very high rate of accretion occurred to Te Afualiku, Motugie, Amatuku, Fuafatu, Matiko, Luamotu, Funafala, Avalau-Teafuafou, and Falaoigo islets, major net erosion occurred to Faugea and Tefala, and only Vasafua was found to lost after 2005.