Strategi mitigasi tsunami berbasis ekosistem mangrove dalam aplikasi pemanfaatan ruang pantai timur Pulau Weh

Abstract

Pulau Weh located in the path of earthquake zone is an area vulnerable to disasters that can be followed by a tsunami earth quake. Geological disasters which occurred on 24 December 2004 with magnitude 9.0MW power resulted in lost of lives and properties, and damage to mangrove ecosystems, especially on the eastern side of Pulau Weh which is facing the Teluk Loh Pria Laot. The impacts of tsunami on mangrove ecosystem namely lodging, uprooting and breaking. The purposes of this study are:1.Mapping of after tsunami land cover and land use to identify the damage caused by the tsunami inundation, 2. Mapping mangrove ecosystem after tsunami in Taman Wisata Alam Alur Paneh, Teluk Boih, Pantai Lhok Weng 2/Teupin Layeu 1,Pantai Lhok Weng 2b/Teupin Layeu 1b, Lhok Weng 3/Teupin Layeu 2, Pantai Lhut dan Pantai Lhok Weng 1/Lam Nibong, 3.Creating a distribution model based on run up, 4. Creating a level of vulnerability to tsunami hazards, 5. Developing mitigation strategies to reduce tsunami hazards by optimizing the local carrying capacity including increasing the density of mangrove ecosystems and expanding the area of mangrove ecosystems. To know the spread of inundation tsunami, a model builder as one of the GIS applications is used. In this research a run up of 30 meter is applied to know the extent of the inundation distribution that can occur in the land use. The composition of total puddle area of 427.9633 ha is as follows: Mangrove forests: 39,7549 ha, Forest of 303,0701 ha, Vegetation: 25,6609 ha, Land Built: 6,1840 ha, Open land: 53,0234 ha and the area not affected by the tsunami: 568, 4441 ha. Mitigation efforts were carried out by mangrove vegetation. The inundation was reduced to 290.7681 ha with the distribution of mangrove vegetation. Inundation was still there on the east coast of Weh Island, then as mitigation strategies to reduce inundation are by planting mangroves to 102 meters ocean ward and increasing the mangrove ecosystem density to 15 trees per 100m2.

Secara geologi Pulau Weh merupakan daerah yang rawan akan bencana gempabumi yang dapat diikuti tsunami. Hal ini disebabkan Pulau Weh berada pada zona yang rentan akan gempabumi. Seperti bencana gempabumi yang terjadi pada tanggal 24 desember 2004 dengan kekuatan 9,0 MW atau 9,3 diikuti dengan tsunami. Tsunami dengan tinggi gelombang datang (run up) setinggi antara 2-5 m yang terjadi berulang kali sebanyak 4 kali mengakibatkan sebaran genangan/ inundasi seluas 50 m dari garis pantai, sehingga menimbulkan kerusakan. Kerusakan yang terjadi antara lain ekosistem mangrove, bangunan seperti rumah penduduk, sekolah, kantor, kedai, tempat penginapan dan infrastruktur. Lokasi kerusakan terdapat di sisi timur Pulau Weh yang berhadapan langsung dengan Teluk Lho Pria Laot. Jenis kerusakan pada ekosistem mangrove seperti batang pohon patah, tercabut dari akarnya, bahkan ada yang tersapu oleh tsunami. Lokasi kerusakan ekosistem mangrove terdapat di pantai TWA Alur Paneh, Lhok Weng 2/ Teupin layeu 1, Lhok Weng 2b/ Teupin Layeu 1b, Lhok Weng 3/Lam Nibong, Pantai Lhut 1, Pantai Lhut 2 dan Lhok Weng 1/Lam Nibong.