Analisis Jaringan Sungai Ciliwung Hulu untuk Menentukan Hidrograf Banjir

Abstract

Hydrograph is a graphical representation of flow with time. Hydrograph shape is determined by the rainfall input and morphometry of the watershed. Upper Ciliwung watershed contributes greatly to the floods that hit Jakarta. This study aimed to determine the characteristics of the Upper Ciliwung river networks and analyze the flood hydrograph pattern formed by the river network density. Determination of the characteristics of stream network is based on SRTM DEM 90 m x 90 m, and it is obtained that the Upper Ciliwung river has four Strahler river order with length ratio (RL) and branching ratio (Rb) that were different for each river order . Flood hydrograph was calculated using geomorphology convolution method and the simulated discharges were compared to observed discharges recorded at the Katulampa station for two rainfall events on January 16, 2013 and March 4, 2013. Based on the values of Nash-Sutcliffe coefficient obtained from the comparison of simulated discharge and observed discharges that were 0.72 for January 16, 2013 flood and 0.66 for March 4, 2013 flood, it is concluded that flood could be determined using geomorphology convolution method based on the river network density from SRTM DEM data.