MANGROVE BELT EFFECT IN REDUCING TSUNAMI WAVE HEIGHT (Case Study: Tsunami at Nanggroe Aceh Darussalam)

Abstract

Mangrove forest is important ecosystem in coastal zone area. Mangrove forest, which is famous as a green belt or mangrove belt, except providing the habitat for wide range species, source of food and forestry product is also, protects the properties, infrastructure, lives and productive economic activity on coastline from wave and storm energy, which is the major caused of erosion process in coast. Mangrove belt is also proved to be a good natural barrier against tsunami. During the tsunami disaster in Indonesia, at December 26th 2004, an area, with extensive mangrove tree, were far less badly hit than places where the mangroves had ripped out and replaced by beachfront hotels and prawn farms. Mangrove trees have an intricate root system. It develops anchor or props for mangrove trees to stand up against the wave, wind and current. And it gives a roughness to bottom sea, so the wave celerity is reduced. By using a Delft-3D-Flow program, the effect of mangrove belt in reducing tsunami wave height could be simulated. The result is one hundred and twenty eight wide of mangrove belt, with density three trees per one meter square gives maximum twenty six percent of wave height reduction