Study of Coastal Morphological Changes by Tsunamis in Aceh (Indonesia) Using Satellite Images

Abstract

This study identified the coastal morphological changes caused by tsunamis that occurred in Banda Aceh, Lampuuk-Lhoknga, and Meulaboh. The morphology of study areas was drastic changes during the 2004 tsunami and followed by the 2005, 2010, and 2012 tsunamis. Time series of Landsat satellite images and tidal data were collected during the period 1988-2020 and analyzed using DSAS (Digital Shoreline Analysis System) analysis method. The main aim of this study is to monitor recovery, trend development, and controlling factors of the coastal morphology before and after fifteen years of the 2004 tsunami. In Banda Aceh, the shoreline shift in the 2004-2005 period shows an inland retreat trend, with an average NSM (net shoreline movement) value of -644.69 m. The EPR (end point rate) value for the 2005-2020 period reached 21.31 m/year, but the recovery of the 2020 shoreline position has not returned to the original position before the 2004 tsunami. The significant shoreline retreat and land loss with an average NSM value of -40.59 m in the period 2004-2005 occurred on the Lampuuk and Lhoknga beaches. The 2020 shoreline of Lampuuk beach underwent a recovery with accretion. Nevertheless, Lhoknga beach is still experiencing apparent erosion. The recovery of the Meulaboh east coast was fast as evidenced by the development of the annual growth of spit features. The coastal morphological changes are influenced by complex interactions between natural and anthropogenic processes. The 2004 tsunami was the major factor to change the coastal morphology in the study areas.