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Field study on planted forest structures and their role in protecting communities against tsunamis: experiences along the coast of the Biobío Region, Chile

Rodríguez, Rolando, Encina, Pamela, Espinosa, Miguel, Tanaka, Norio
Landscape and ecological engineering 2016 v.12 no.1 pp. 1-12
Cupressus macrocarpa, Pinus radiata, coastal forests, coasts, field experimentation, remote sensing, salinity, shelterbelts, stems, trees, tsunamis, villages, Chile
A field study using satellite images was carried out to analyze the effect of coastal vegetation in mitigating the impact of a catastrophic tsunami on coastal villages in the Biobío Region, Chile, in February 2010. Two types of stand, Pinus radiata D. Don forests and Cupressus macrocarpa Hartw. shelterbelts, appear to have protected coastal areas behind them from the direct impact of the tsunami. The impacts of the horizontal and vertical structures of these coastal forests on the drag forces were analyzed by observing the characteristics of Pinus radiata forests and Cupressus macrocarpa shelterbelts. The stands absorbed the impact of the tsunami without incurring broken stems or uprooted trees due to their diverse horizontal structure, as they contained short trees with various diameters. However, small areas of the stands were damaged by salinity after the tsunami. For this tsunami, which was less than 3 m high, the horizontal and vertical structures of the P. radiata and C. macrocarpa stands provided effective protection for coastal villages since they reduced the velocity and height of the tsunami. A shelterbelt consisting of three rows of C. macrocarpa in front of the tsunami and a P. radiata forest with a density of 11 trees/100 m² and a width of >50 m immediately behind the shelterbelt are suggested as a means of protecting communities along the coastline of the Biobío Region against tsunamis.