2D modelling of wave propagation at the Palu estuary after the 2018 tsunami

Abstract

In September 2018, the powerful and shallow earthquake with a magnitude of 7.4 rattled Sulawesi Island. This earthquake triggered a tsunami disaster in Palu Bay which caused changes in the morphology of the Palu Bay coastline. The coast along Palu Bay underwent significant changes due to the impact of the tsunami waves. Changes in the morphology of the beach also affect the characteristics and current waves that enter the mouth of the Palu River. This study aims to analyse the propagation and transformation of waves entering the Palu River estuary. Wave analysis and simulation was performed using the Surface-water modelling system (SMS) package generated from the Meteorological, Climatological, and Geophysical Agency (BMKG) wind data. Statistical analysis of wind data was carried out using Windrose Software and the Shore Protection Manual method to predict deep sea waves. This forecasting method is employed in a hybrid manner with the Weibull method to determine extreme wave heights for 50-year return periods. The simulation results using the CGWAVE model show that the maximum wave height coming from north direction approaching the mouth of the Palu River is 1.3 m. Furthermore, the wave height coming from the northwest approaching the Palu River estuary is 0.8 m.