IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Poster presentation 1833
Study on the effect of coastal forest against tsunami, Case study on 2006
JAVA Tsunami around Pnagandaran, Indonesia
Dr. Kenji Harada
Disaster Reduction and Human Renovation Inst. Reserch Scientist IASPEI
Aditya Riadi Gusman, Hamzah Latief, Yuichi Nishimura, Yoshiaki Kawata
At the 2004 Indian tsunami, many stories on tree and forest were reported. Some people were survived
due to catch on tree. Some area was small damage by the forest effect of tsunami mitigation and
blocking driftage. These effects of coastal forest against tsunami were known before 2004 tsunami.
However several primary studies were discussed, the tsunami mitigation effect cannot be established
quantitatively. Regardless of this, coastal forest are used as the countermeasures to mitigate tsunami
impact in the rehabilitation and reconstruction plan. In such conditions, the concern and importance for
the role of coastal forest and mangrove on protection are growing big from many specialized fields. The
workshop on the coastal forest and tsunami are organized in 2006 by FAO (Food and Agriculture
Organization of United Nation) in Khao Lak, Thailand. In this workshop, various authorities related in
coastal forest and tsunami are joined and discussed on the role of coastal forest. The key results for
evaluation of this workshop are (1) The level of knowledge and understanding of the functions of
forests and trees in coastal protection is still insufficient and there is a lack of multidisciplinary research
and cooperation in this field, (2) The degree of protection offered by coastal bioshields depends on a
number of variables, including: i) the characteristics of the hazard itself, ii) the geomorphologic features
of the site and iii) the characteristics of the bioshield, (3) Care must be taken to avoid making
generalizations about the protective role of forests and trees based on evidence from one or a few
areas, (4) The options for protection include: soft solutions hard engineering solutions and a hybrid of
the two. If none of these are appropriate and viable, it may be necessary to zone coastal land use to
prevent (further) settlement and construction of valuable assets in the vulnerable zone. And scientific
knowledge should be translated into policy-relevant information for decision makers and into technical
guidelines.In this study, the coastal forest effect and its limit are discussed based on some tsunami field
investigation. The field investigation in the 2006 Java tsunami was carried out on coastal forest
conditions and tsunami inundation level around Pangandaran and Cilacap, Indonesia. In this field survey
case, species of tree are Coconuts tree, Casuarina, Pangdanus and Mangrove. On the type of tree, the
shape of tree, tree height, location from sea and so on are different and we measured these conditions.
Shuto(1987) is analyzing on the effect of coastal forest from five tsunami events. The limit conditions of
coastal forest effect are shown in the case of pine tree in Japan. Our measurement data and some other
field survey data in 2004 Indian Ocean Tsunami of are collecting and combined for compare the effect
of coastal forest against tsunami and limitation. From these analyses, the limit conditions are shown
depend on the kind of tree and local conditions.
Keywords: coastal forest, java tsunami 2006, bioshield