Storm surge induced by 2019 Tropical Storm Pabuk and impact on the shoreline in Kuala Nerus Terengganu, east coast of Peninsular Malaysia

Abstract

This study investigates the one-year shoreline impacts of 2019 Tropical Storm Pabuk and the morphological changes of beaches in the study area of Kuala Nerus in Malaysia mediated by the hydrodynamic conditions. The study used a numerical model that utilised the two-way coupling of the wave and hydrodynamic model of MIKE 21 to simulate the event. The impact of the event was determined by employing the Digital Shoreline Analysis System, along with regular in-situ measurements of beach profiles carried out monthly. The results show a significant retreat rate of −58 m/year at Tok Jembal, highlighting the significant erosive impact, particularly on the northwest side of the airport. Despite a storm surge height below the extreme thresholds (>1 m), the beach morphology and the presence of coastal protection structures exerted a significant modulating influence. Batu Rakit, which is characterised by a wide beach, exhibited increased wave run-up and erosion resulting from the combined effect of a tidal surge of 0.64 m and significant wave heights of more than 1.12 m. UMT and Teluk Ketapang, on the other hand, which are shielded by coastal structures and influenced by longshore currents, experienced beach accretion. The intensification of the recirculation current with the surge is postulated to have contributed to the pronounced erosion at Pengakalan Maras. Although the overall magnitude of the storm surge was not exceptional, this study emphasises the importance of studying the effects of storm surges on monsoonal coasts. The intricate interplay between waves and currents, elucidated by coupled hydrodynamic and wave modelling, is crucial for understanding the consequences of storms and for proactive coastal management strategies. This study emphasises the crucial role of detailed hydrodynamic modelling in developing effective erosion control measures, which is an ongoing challenge for coastal communities.