PENGEMBANGAN KRITERIA PERINGATAN BENCANA ALIRAN LAHAR DINGIN DI WILAYAH KALI GENDOL GUNUNG MERAPI

After the eruption of Mount Merapi in 2010 led to the lahar flow disaster on the region of the volcano slopes. Given the dangers and impact caused by the lahar flow, it needs to develop a warning criteria for lahar flow disaster with a simple method that use the limited of existing data and parameters. One of method which is most likely to perform is analysis of rainfall data to predict occurence of lahar flow in Gendol River. The method of analysis is done by using a setting of standard rainfall for warning and evacuation used for the prediction of sediment disasters based on Guidelines for the Development of Warning and Evacuation System Against Sediment Disasters in Developing Countries, published by the Ministry of Land, Infrastructure and Transport (MLIT) Infrastructure Development Institute - Japan, 2004 by setting the critical line, warning line and evacuation line based on correlation graph between rainfall intensity (mm/h) with working rainfall (mm). In this research can be arranged the critical line (CL) which can be used to predict the occurrence of lahar flow based on the rain characteristics namely working rainfall and rainfall intensity. Furthermore it can be established the warning line (WL) and the evacuation line (EL) as a basis for determining the standard rainfall for warning (R1) and standard rainfall for evacuation (R2). The value of R1 obtained ± 6 mm and for R2 ± 29 mm. The value of R1 and R2 is strongly influenced by availability of rainfall data and occurrence of lahar flow. The results of this research expected can be used as input for the warning criteria development of early warning system lahar flow disaster on the slopes of Mount Merapi, particularly in the area of Gendol River