Shoreline Change Dynamics using Digital Shoreline Analysis in Cemara Besar Island

Abstract

This paper will describe a study to find out the shoreline changes that occurred on Cemara Besar Island along with the accretion and abrasion. Data taken from the images was obtained through google earth as a result of radiometry and geometry correction from Landsat satellites in the last 5 years. Wind data is obtained from ecmwf interm every season for 5 years. Analysis of shoreline changes was carried out using the DSAS (Digital Shoreline Analysis) method and analyzed by wind and sea wave factors in each season. The results of the analysis obtained LRR and EPR values for 5 years, the extent of changes in island land mass, the value of Hs and Ts from the results of wave forecasting using wind data. To simplify the analysis, Cemara Besar Island is divided into 9 segments based on variations in LRR values. The results show that in general Cemara Besar Island have very high accretion in segments A, B and E with an average of 3.61 m and very high abrasion occurred in segment F with an average of -1.01 m. Abrasion occurs with the greatest speed of change in segment A with an average of 4.64 m/year and the largest accretion rate in segment F with an average of -1.21791 m/year. Analysis of oceanographic factors through wave forecasting shows that in the west and transition I season, waves occur with Hs 1.21 m, greater than the eastern season and transition II season with Hs 0.91 m. wind direction from north dominant direction 377.50 in west season and transition I, and from east direction 67,25 in east season and transition I season. Direction of wind blowing influences wave propagation and direction of wave coming towards shore which affects sediment transport which produces accretion and abrasion on the Cemara Besar Island.