Untitled - Teknik Kelautan / ITB

Investigation of Coastal Vegetation Characteristics and Field
Experiment on Strength of Casuarina in Indonesia
Aloysius Bagyo Widagdo 1 , Chaeroni 1 , Jainindra Setiawan 1 , Hideo Matsutomi 2
& Kenji Harada 3
1 Coastal Dynamics Research Center, Agency for the Assessment and Application of
Technology, Yogyakarta, INDONESIA
2 Graduate School of Engineering and Resource Science, Department of Civil and
Environmental Engineering, Akita University, JAPAN
3 Center for Integrated Research and Education of Natural Hazards, Shizuoka
University, JAPAN
Email: bagyowidagdo@yahoo.com
Abstract. Indonesia’s coast has been recognized as an area that has a risk of tsunami
hazard. Coastal forest is considered as affective countermeasure against tsunami
disaster in Indonesia. One of vegetation that was assessed for the purpose is
casuarina (coastal pine tree). Physical modeling as well as numerical simulation has
been used to assess the effectiveness. In this study, field investigation was preferred
to compliment the previous tool. The field investigation was held not only to
investigate characteristic of the trees, but also to measuring strength of the trees.
Relation of the forces used to pull the tree and bending positions of the tree were
recorded. Uprooting experiments were also conducted Results of the investigation
showed that the diameter is increased linearly by tree age, and the tree height is
increased logarithmically by tree age. For trees with age of 5-7 years old, generally
the tree will be collapse for the force bigger than 10 kN. Meanwhile, for uprooting
the tree, it requires force almost 3 times, i.e. up to 27- 30 kN.
Keywords: coastal vegetation characteristics; field experiment; strength of tree;
tsunami runup.
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