Decadal shoreline changes and effectiveness of coastal protection measures post-tsunami on 26 December 2004

Abstract

Shoreline changing position along the coast is an immediate and long-term indicator determined by the interplaying driving forces across the dry and wet parts of coastal areas. Extreme waves, such as tsunamis, may result in a remarkable shift of shoreline position and a change of sediment transport regime, thus potentially inducing coastal hazards. This work investigates the multi-temporal changes and development of shorelines at the tsunami-affected coast nearly two decades after the Indian Ocean tsunami on 26 December 2004. Additionally, the dynamic responses of the coast to the man-made coastal structures as a means of protection measures during the observed period are also evaluated. This study uses the US Army’s Digital Shoreline Analysis System (DSAS) extension in the ArcGIS to calculate the multi-temporal shoreline changes and erosion/accretion rates. Multi-temporal shoreline vectors delineated from the LANDSAT satellite images are utilized to calculate the Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR) for the respective short-term and decadal-term shoreline change analysis. The shoreline change rates are examined at the three shoreline segments at Aceh coast, the north tip of Sumatra Island of Indonesia. The results show that Segment A has the highest erosion rate due to the 2004 tsunami (− 395.19 m/year) compared to Segment B (− 26.46 m/year) and Segment C (− 74.26 m/year). The 2004 tsunami has changed the coastal states from erosional coast prior to the tsunami to accretional coast in Segment A and C, and the eastern side of Segment B in almost two decades since the tsunami. Consequently, ignoring such phenomena in designing coastal protection measures may lead to structural failures such the ones identified in the investigated coast. Thus, a thorough investigation of shoreline change is fundamental for coastal managers, particularly in determining appropriate coastal protection measures.