Use of trees as a tsunami natural barrier for Concepcion, Chile - 11th International Coastal Symposium

Abstract

This paper presents some physical models, numerical simulations and field surveys as part of a research project on the use of tree barriers as a mitigation measure against tsunamis in the Bay of Concepcion, Chile. The physical model was performed using a mechanical system in one side of a flume, with a lock gate and steel frame, which maintained a water volume in order to generate a controlled increment of the mean water level. On the other side of the flume, a beach with slope 1:13 was installed. The tree barriers were modeled with cylindrical wooden sticks, and four different configurations were tested. Additionally, a numerical model of the 2010 Chilean tsunami was performed with TUNAMI-N. In all cases, the initial condition was defined by means of a static source. Finally, a field survey of the affected areas of the Biobio Region was carried out after the 2010 tsunami. The physical experiment demonstrated that these kinds of barriers can successfully absorb the impact of a tsunami in coastal regions. The numerical model showed that the area of flooding and the inundation height would decrease in developed areas, which could significantly reduce damage to property and individuals. Finally, the survey showed that in the most affected areas, pinus radiata and populus alba with trunk diameters larger than 20cm were not damaged. These observations demonstrate the feasibility of using this kind barrier as a mitigation measure.