Evaluation of the impacts of harbour engineering, Anibare bay, Republic of Nauru (RON)

Abstract

In summary, the coast is part of an emergent, Holocene reef-carbonate system, with the beach being comprised entirely of carbonate sediments developed on phosphate-rich, cavernous, dolomite limestone bedrock. The coastline is partly rocky with classic karst limestone pinnacles found throughout the bay. The reef is a coral dominated system and is narrow and well-flushed, with many closely-spaced reef channels. The coastline at Anibare Bay is an active and dynamic one. The relatively coarse admixture of abraded sand and gravel and highly abraded karts pinnacles testify to this. The beach at the development site is moderately steep and has experienced erosion in the recent past and show sign of recent and current erosion, with fresh erosion scarps. The harbour development appears to have increased this erosion at the localized level, at the adjacent, undeveloped coastal segments. The topographic elevation of the coastal land areas are relatively low with respect to CDL and MSL and under EHWST or during windy and low pressure systems, when large (3 m +) waves approach shore, from the East, the beach, coastal road and adjacent areas can be easily overtopped. The relatively nanow and almost flat backreef and reef flat, together with the numerous closely-spaced reef channels make it almost impossible to dissipitate significant wave energy and prevent overtopping during these conditions. In addition, the almost featureless backreef cannot trap sediments entrained in longshore currents and therefore, sediments removed from the local areas can be completely lost from the coastal system in Anibare Bay.