ANALISIS KEJADIAN BANJIR MENGGUNAKAN METODE AMBANG BATAS

Abstract

Flood is a puddle of water on the soil surface, which occurs due to the bad drainage system, so that the rain water spill or water delivery from upstream areas cannot be accommodated by the river. Threshold Level Method (TLM) is a method used to determine the threshold of flooding which is further processed into data on the number and duration of flood events and the number of exceedance stream flow. This research was conducted from July 2014 to January 2015. The aim of this research was to determine the discharge thresholds expressed as a threshold value of flooding in 24 watersheds in three areas of UPT PSDA (Water Resource Departmet) East Java using discharge data records in period 1996-2001. The determination of flooding threshold used TLM method using percentile value of 90 (Q90) from the data on discharge record of each watershed observed. Thus, the occurrence of discharge that exceeded the predetermined threshold would be categorized as a flood event. Based on the data analysis in 24 watersheds spread over UPT PSDA Malang, Madiun and Bojonegoro regions using discharge data obtained for 6 years, the biggest flood discharge threshold was in Babat Watershed by 990 m3/s.