MSc: Ms. Lavenia Tawake - Institute of Applied Science
Degree: Master of Science in Marine Science
Researcher: Lavenia Tawake
Thesis title: Coastal processes affecting beach erosion; a case study of Votua village in Sigatoka on the Coral coast, Fiji Islands.
Thesis Title: Coastal processes affecting beach erosion; a case study of Votua village in Sigatoka on the Coral coast, Fiji Islands.
Principal supervisor: Dr. Suzanne Pohler
Co-supervisor: Dr. Paulo Vanualailai
The purpose of this research was to assess beach erosion at the village of Votua along the Coral Coast of Viti Levu in the Fiji Islands. The history of coastline change (1967 to 2000) was determined using the GIS MapInfo software and historic information obtained from the community. In addition beach profile changes were determined over a period of one and half years (from mid April 2004 to mid October 2005) and the dominant coastal processes were observed. Information gathered from this study will form part of the baseline data for further beach monitoring and optimum management of the beach environment.
The results of the study have demonstrated that the beach at Votua has been experiencing chronic erosion over the 33 years between 1967 to 2000. The shore has been receding at approximately 0.8m/year resulting in the loss of the white sandy beach and most of the large coastal trees that used to exist there in the past. The geomorphology and bathymetric structure of the coastline to the inshore area governs the characteristics that determine the coastal processes that occur at Votua. The consistent current circulation inside the basin-like structure bounded by the east and west ridges, the coastline and the reef crest causes water to move toward the deeper areas of the reef flat then toward the channel regardless of the tide. This indicates the major transport pattern of sediments from the beach to the channel and out into the Votua canyon.
The beach profiling study showed that the erosion rates vary significantly with time with more erosion in the wet summer seasons from November to April than in the dry winter season from May to October. Erosion rates also vary across the length of the beach in relation to the sources and sinks of beach material and exposure to wave action. Overall erosion occurred during the one and half years research time at approximately 2 to 7cm/year. The different temporal scales of analyses yield different erosion rates (i.e. 0.8m/yr for 1967 - 2000 vs. 2 to 7cm/yr for 2004 – 2005) because other factors such as the impact of climate change, sea level rise and cyclones over the years contribute to the longer term erosion. More research and monitoring are required to better evaluate and understand beach erosion at Votua.