Author(s): S. Harish; B. Jochems; Jan Oetjen; Holger Schüttrumpf; V. Sriram; S. A. Sannasiraj

Linked Author(s): Sannasi Annamalaisamy Sannasiraj

Keywords: Tsunami bore; Vegetation; Force reduction; Froude number; Coastal forests

Abstract: During the 2004 Indian Ocean Tsunami and the 2011 Tōhoku Tsunami, traditional embankments were observed to offer insufficient damage protection for coastal settlements. In addition, the endangerment of coastal forests further necessitates the synergistic inclusion of coastal vegetation as a coastal flood mitigation measure. Therefore, in the present experimental study, the suitability of coastal vegetation for tsunami force reduction, with a particular focus on shorefront buildings, is investigated. In the experiments, the vegetation model of variable width in the streamwise direction was investigated with varied Froude flow regimes and discharge conditions. Evaluations encompassed the flow-directional horizontal force on the building, the bore depth in front of the building and overturning moment on the building during the quasi-steady flow phase. The applied variations of vegetation widths led to reductions of the above-mentioned investigated quantities of −1.15 to 37.79%, −0.25 to 20.64% and −3.89 to 40.61%, respectively. Furthermore, a set of empirical equations is proposed, estimating the reduction of force, moment, and bore depth at the structure front depending on the vegetation width and the Froude number. The provided insights emphasize the importance of coastal forests and support the development of design guidelines for buildings located behind natural tsunami defence systems.

DOI: https://doi.org/10.1007/978-981-97-6009-1_19

Year: 2022