The geographical condition of Indonesia lies in the circum pacific volcanic arc and the trans-Asiatic volcanic belt with many mountain range. The existence of 129 active volcanoes or 17 percent of the total active volcanoes in the world, plus the heterogeneous relief of the land contours with relatively high slope, has quite high potential for disasters. Not to mention the diverse patterns and long rivers with many courses. This condition causes frequent sediment disasters, including landslides, sedimentation of reservoirs, cold lava floods, and flash floods.
This issue is a challenge for the government, professionals, business, academia and society, which require preventive measures and mitigation of natural disasters in an integrated, effective, and efficient way. It must be done so that the risks and negative impacts can be reduced as much as possible. "Natural disaster management must be more integrated since the start of planning, programming, action plans, and implementation with adequate monitoring and evaluation," said the Professor of Hydrology UGM, Prof. Ir. Djoko Legono, Ph.D., in National Seminar on sediments Disaster Management, which is a cooperation between Masters in Management of Natural Disasters UGM with Ministry of Public Works and JICA, Thursday (21/10).
Djoko Legono expressed that the current extreme climate change is causing a quite high intensity of rainfalls. This is very influential on sediment disasters in some regions. "The condition of our region which is dominated by a high slope, unstable areas, and many rivers and streams resulted in high number of sediment disasters in an incessantly high rainfall," he explained.
Meanwhile, Drs. Endro Santoso, M.Si. of the Meteorology and Geophysics Agency (BMKG) said that the current high level of rainfall is more influenced by El Nino-La Nina and Dipole Mode. He explained that the dynamics of atmosphere and marine conditions will continue until February 2011, indicating early rainy season in most parts of Indonesia. "As much as 58.6 percent of regions have normal rainfall level, 37.3 percent above nomal, and 4.1 percent below normal," he said.
Endro mentioned Sumatra regions that experienced above normal rainfall level, including Central Aceh, most of North Sumatra, Lampung and Bangka. In Java this includes Jakarta, part of West Java (Sukabumi, Cianjur, Garut, Tasikmalaya, Sumedang), parts of Central Java (Tegal, Brebes, Pekalongan, Kendal, Banyumas, Surakarta, Rembang, Bojonegoro), some parts of Yogyakarta, and part of East Java (Pacitan, Malang, Lumajang, Sidoarjo, Pasuruan, and northern parts of Jember). Regions outside Java which experienced above normal rainfall include most of Bali, West and Central Lombok, and part of Kupang, East Kalimantan, South Sulawesi, Gorontalo, North Sulawesi, North Maluku, Sanana, Saumlaki, and the south of Merauke.