Analysis of Shoreline Change in Southwestern Coast of Ternate, North Moluccas Province

Abstract

A study pertaining analysis of shoreline change in southwestern coast of Ternate Island, North Moluccas Province has been conducted to analyze the shoreline change (abrasion and sedimentation) for 11 consecutive years from 2001-2011. The background of this study was based on the reality that southwestern coast of Ternate Island has undergone serious abrasion and sedimentation reaching the residential villages. There were no comprehensive studies yet conducted on how serious the coastal changes occurred. This study was aimed to analyze the wave transformation and shoreline change in southwestern coast of Ternate Island. The transformation of wave spectra in coastal environments is predicted with Nearshore (NSW modeul) MIKE 21 DHI models. Wave the paramters include the effects of refraction, nonlinear wavewave interactions, and parameterizations of wave breaking and bottom friction. Analysis was done applying two approaches i.e. using MIKE LITPACK DHI model and image digitation using Landsat Image 7 ETM+. Results of wave tansformation analysis is a waves coming from the west direction parallel to the Sasa Beach in station C, so the station C have a major impact of the wave transformation. Results of image analysis was used as comparison to validate the output of MIKE LITPACK DHI model. Overlying between results of model analysis and results of image analysis showed similar contour patterns of shoreline changes. Based on the results of model analysis, the highest abrasion level was found at station C (Sasa Beach) as far as 83.67 m and sedimentation occurred at station B as far as 45.69 m, whereas, based on the results of image analysis, the highest abrasion was found at station C as long as 27.14 m and sedimentation was concentrated at stasiun E as long as 24.09 m. The extent of abrasion and sedimentation was influenced by wave action occurred and activity of sand mining by local people in southwestern coast of Ternate Island.