Geospatial Analysis of Coastline Erosion Along Pulau Tuba, Langkawi

Abstract The erosion in Malaysia has brought attention to many authorities especially the coastline in the eastern part of Peninsular Malaysia. Although the erosion in the northern part of Peninsular Malaysia does not receive as much attention as the eastern part of Peninsular Malaysia, however, the issue should not be neglected. High spatial resolution satellite imageries were used for the extraction of coastline and classification level of erosion rate along with the Pulau Tuba. The coastline data was extracted using two different methods known as Maximum Likelihood (ML) and On-Screen Digitizing (OSD) in the determination of the best approach of coastline detection from the Sentinel-2 data of the year 2016 and 2019. Furthermore, the level of erosion is made based on the physical and economic parameters outlined by the National Coastal Erosion Study 2015 (NCES). Due to some inevitable constraints of Movement Control Order by the Malaysian government due to the COVID-19 pandemic, physical observation data of Pulau Tuba were collected via Google Maps. The information acquired includes type of coastal geomorphology, land use, development on the area, activities conducted, and adaptation of erosion if any. These data were utilized to determine the erosion rate and categories using the proposed model by NCES for five divided management units (MU) of the Pulau Tuba areas utilizing Erdas Imagine and ArcGIS software. The analysis found that the ML approach has under-detected the coastline length between 3.19% to 45.0% as compared to OSD for both years of 2016 and 2019. Rate of erosion for Pulau Tuba based on the NCES approach found that the highest erosion rate occurred at the MU1 (Pulau Dayang Bunting- Pulau Tuba causeway) with 2.91% and classified as K1 (critical erosion category) with a value of 4.39 m/yr−1 and the highest accretion rate at the MU3 with 3.06%. The critical erosion category was associated with the MU that has significant development and on-going activities that occurred in the area especially in MU 4 (Pulau Tuba) and MU 5 (Teluk Berembang). Other than that, the high number of erosions occurred in that section is due to the exposure of waves, wind, currents, and tides.