Effectiveness of an Elevated Road in Reducing Inundation Area of the Coast of Palu, Sulawesi, Indonesia

The 2018 Sulawesi Earthquake and Tsunami was triggered by an earthquake with a magnitude of Mw 7.4. The event severely damaged coastal areas along the coast of Palu. Thus, mitigation plans are urgently needed. We assessed the effectiveness of an elevated road for tsunami protection along the coast of Palu. Delft3D and Delft Dashboard were used to simulate hypothetical earthquake-generated tsunamis. There are four fault failure scenarios based on three tectonic faults: the North Sulawesi Megathrust, North Makassar Strait, and Central Makassar Strait. The model simulates the tsunami propagation from the source to the coast. The highest tsunami is generated by a combination of the North and Central Makassar Straits. The effectiveness of an elevated road was assessed for four scenarios. Simulation was conducted with various heights of an elevated road along the coast of Palu, and Palu Barat and Ulujadi districts. These districts were chosen since they are densely populated and were severely damaged or destroyed by the 2018 Sulawesi Earthquake and Tsunami. The optimum tsunami impact reduction is obtained when the height of the seawall is no less than 6 m, which can reduce up to 81.7% of total inundation area without any protection.