APLIKASI SISTEM INFORMASI GEOGRAFIS UNTUK MENDETEKSI POTENSI BENCANA TANAH LONGSOR DAN BANJIR BANDANG (Studi Kasus: Daerah Aliran Sungai Podi Kabupaten Tojo Una-una Propinsi Sulawesi Tengah)

Abstract

There are many landslide disaster potential area in Eastern Central Sulawesi. This landslide is potentially triggering flashflood. I the middle 2007, a massive flash flood was struck in 4 district in Morowali residence. Beside Morowali Residence, the other residence which has the same problem is Tojo Una-una Residence. It since the two residence was located on the same mountain. So, it means the same catastrophic disaster would possible occurred in the Tojo Una-una Residence in the next. From many rivers in Tojo Una-una’s residence, the most frequently occurred flash flood is Podi River. However, the geospatial survey and field survey has worked on the site directly. The geospatial survey was made by satellite imaging then analyze it by some computer software, and make some interpretation. The field survey has worked further by visual analyzing, taking picture for documentation, taking soil or rock sample, and interviewing the local citizens. The result is critical slope and damaged was observed, sedimented area, the potential area to sledge has appear. There is many additional important information got, such as the + 169,84 Ha critical slope fail area, the + 300 m height of critical slope, and the potential volume of the next landslide material is + 509.250.000 m3. From land survey, the information gets is the vegetation on the location is still in good condition. The top soil for plant nutrition and grew media just 1,0 – 2,0 m depth. The clay layer is only about 30,0 cm depth. The weathered rock is dominating on this soil stratification. Finally, it can conclude that the remote sensing technology is very helpful and useful to makes some preliminary interpretations. This results most followed by field survey to make sure and high accuracy about the real situations there. The landslides were caused by weathered rock, high rainfall intensity, mega landslides was occurred in upstream, The new landslide profile was made the contour bowl alike and this condition is believed why does The Podi River always caused flash flood in the huge amount. Keywords: Geographic Information System, remote sensing, natural disaster, landslides, flash flood.