Numerical simulations of land cover roughness influence on tsunami inundation in Ulee Lheue Bay, Aceh-Indonesia

Abstract

Most of the flat area at Ulee Lheue Bay of Aceh Besar is affected by tsunami wave during the 2004 Indian Ocean Tsunami. The coastal area with no significant barrier caused tsunami wave inundating further inland. Coastal forest is known as an effective way to reduce tsunami impact in the coastal environment. In this paper, we used 2 Dimensional Horizontal (2DH) numerical model Cornell Multi-grid Coupled Tsunami (COMCOT) and Delft3D to evaluate the coastal forest influence which interpreted by variable Manning's coefficient of tsunami inundation. We also discussed the hydrodynamic characteristic of tsunami wave such as maximum water elevation and flow velocities to evaluate how effective is the coastal forest in reducing tsunami impacts at Ulee Lheue Bay. The results showed that the coastal forest effect is not significant difference both water elevation and tsunami inundation. Meanwhile, the coastal forest with 100 m width can reduce tsunami wave velocities about 40 %. It is important because high tsunami velocities caused severely eroded in the coastal area.