KAJIAN EFEKTIVITAS NORMALISASI SUNGAI BEKASI DALAM MEREDUKSI RESIKO BENCANA BANJIR DI KOTA BEKASI

Abstract

This study evaluates the effectiveness of Bekasi River Improvement based on rainfall data, land coverage, and the characteristics of Bekasi watershed. This study aims to calculate the design flood discharge with return period of 2, 5, 10, 25, 50, and 100 years, also designing a new cross section of Bekasi River. The modeling of the flood also carried out to evaluate the effectiveness of Bekasi River improvement in the present year 2022 and in the future in 2050. Flood simulation will be done using HEC-RAS V.6.0 with the use of design flood discharge with 25 years return period. The rainfall data will be processed with Thiessen Polygon methode to obtain the value of average rainfall, then the average rainfall is calculated using the Normal, Gumbel and Log Pearson III method to obtain the value of design rainfall. The design rainfall that has been obtained are tested using the Chi Square and Kolmogorov-Smirnov method to know which distribution method that can represent the whole rainfall data. The design rainfall that is chosen are used to calculate the rainfall intensity using Mononobe equation. Using Nakayasu Synthetic Unit Hydrograph, the characteristics of Bekasi watershed can be processed to obtain the value of unit hydrograph. The result of rainfall data processing is the value of the design flood discharge with return period of 2, 5, 10, 25, 50, and 100 years. Flood discharge with 25 years of return period is used as the based of Bekasi River cross section design and used for the flood simulation. Based on the flood simulation that has been done using the HEC-RAS V.6.0 software, it can be known that the Bekasi River improvement program able to reduce 95% of flood area that is formed in the year 2020 and 93% in the year 2050.