ANALYSIS OF FLOOD CAPACITY ON A CROSS-SECTION OF THE SADAR RIVER FOR RIVER NORMALIZATION PLANNING

Abstract

Based on flood event records, the Sadar River often experiences flooding problems, therefore research is needed to overcome the flood problems in the Sadar River. The purpose of this study is to calculate the capacity of the Sadar River cross-section to accommodate the incoming planned flood discharge and to find out which river cross-section locations are potentially flooded. This study uses manual calculations for the planned flood discharge and the HEC-RAS application in its flood inundation modeling. For the calculation of rainfall distribution, the method used is the Gumbel method. The calculation of the planned flood discharge uses the Nakayasu synthetic unit hydrograph, Snyder synthetic unit hydrograph and ITB-1 synthetic unit hydrograph. Because ITB-1 synthetic unit hydrograph is the largest planned flood discharge, the planned flood discharge of ITB-1 synthetic unit hydrograph is used with a planned flood discharge of Q100 = 502.03 m3/sec. In flood modeling using HEC-RAS, it was found that the river cross-section points that experienced evaporation were at STA 500, 600, 2208, 2950, 4400, 4850, 6400, 6550, 7991, 8300, 12445, and 19400. The solution to the river cross-section points that experienced flooding is to carry out normalization by raising the river cross-section at all STAs by 20 - 100 cm, and normalization in the form of dredging the river at STA 600 to a depth of 50 cm.