Peak Flood Discharge Analysis of the Gajah Wong Sub-Watershed, Indonesia

Abstract

Every year, during high rainfall, the Gajah Wong River overflows and inundates residential areas. The largest flood events on the Gajah Wong River occurred in early 2016 and mid-2016, this disaster caused the Gajah Wong River embankment to collapse, as a result the floods continued to overflow and enter residents' settlements as high as 2 meters. This is because the capacity of the river exceeds the peak discharge. This study aims to calculate the peak discharge using the rational method by utilizing data on daily maximum rainfall in the range from 2001 to 2021. The results of the study show that there was an increase in the inundation area for each flood return period. The peak flood discharge in the Gajah Wong River Segment using the rational method respectively for return floods of 2, 5, 10, 25 and 50 years is 61.41 m3/second, 98.94 m3/second, 123.79 m3/second , 155.18 m3/second and 178.46 m3/second.