CALCULATION OF TRESHOLD VALUE DETERMINATION FOR EXTREME RAINFALL IN INDONESIA

• Main Author: Aprianda, Triyoza
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70786
• Institution: Institut Teknologi Bandung

Treshold value for extreme rainfall in Indonesia is contained in Perka BMKG No. Kep: 009 2010, that extreme rainfall has the lowest intensity of 50 mm/24 hours. Recently, the BMKG raised the threshold for extreme rainfall to 150 mm/24 hours, which is listed on the BMKG official website. However, there has not been a written concept on how to get this value and the reasons for its use. However, this value is set as a standard for extreme rainfall values for one Indonesia. Meanwhile, the unique territory of Indonesia makes the threshold for extreme rainfall values less precise if generalized to a certain value. In this study, will estimate the basis for determining the threshold for extreme rainfall values issued by the BMKG was carried out by identifying the rainfall value in a certain return period using the GEV (Generelized Extreme Value) method. This study uses observational daily rainfall data from 120 BMKG obervation stations in Indonesia.. Then recommend the threshold value of extreme rainfall based on the zoning system for the Indonesian region. The results showed that the extreme rainfall values for the five-year return period at 120 stations had an average a median value closed to the extreme rainfall standards issued by the BMKG. So it is assumed that the standard from the BMKG is the average value os extreme rainfall with a return period of five years. The zoning results show that there are two homogeneous areas as one group, namely the eastern part of south Sumatra with an average threshold value of extreme rainfall that is below the BMKG standard, and the central part of Kalimantan which has an average, 153 mm/day close to the BMKG standard,. Meanwhile, other areas with random patterns are divided into 14 zones, where each zone has various characteristics.