EVALUATION STUDY OF BANKFULL CAPACITY OF THE CITARUM RIVER IN MAJALAYA DUE TO SEDIMENTATION
The village of Majalaya has experienced an increasing frequency of floods each year. Notably, on February 22, 2018, floodwaters covered an area of 5.73 km². Considering the significant sedimentation in the Citarum-Majalaya River, an analysis and evaluation of the changes in the river's capac...
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| Format: | Theses |
| Language: | Indonesia |
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| Online Access: | https://digilib.itb.ac.id/gdl/view/84685 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | The village of Majalaya has experienced an increasing frequency of floods each
year. Notably, on February 22, 2018, floodwaters covered an area of 5.73 km².
Considering the significant sedimentation in the Citarum-Majalaya River, an
analysis and evaluation of the changes in the river's capacity are necessary. This
analysis was conducted using numerical modeling with HEC-RAS 6.3.1, based on
11 years of historical discharge data, comparing the river's condition before and
after normalization. The Nakayasu Synthetic Unit Hydrograph (HSS Nakayasu)
was used to calibrate the flood discharge for the February 22, 2018, event, where
the observed peak discharge was 155.08 m³/s, and the calibrated peak discharge
was 154.93 m³/s, with an NSE of 0.84. Hydraulic modeling calibration was
performed for Manning's roughness coefficient using water surface elevation data,
resulting in a Manning's roughness coefficient of 0.065, indicating a significant
presence of vegetation. For sedimentation calibration, the Englund-Hunsen method
was chosen due to its suitability for riverbed material composed of sand. The
sediment calibration was based on changes in the river cross-section from 2021 to
2022. The comparison of results for river cross-sections RS-1873 and RS-1690
showed similar outcomes. The actual cross-sectional area change for RS-1873 was
2.65 m², while the model's result was 2.97 m², and for RS-1690, the actual change
was 3.40 m², compared to the model's 3.61 m². Over 11 years of modeling after the
Citarum-Majalaya River was normalized, a decrease in river capacity of 50 m³/s
was observed, from the post-normalization capacity of 115 m³/s to 65 m³/s, with a
sediment volume of 1,280,536 m³. After normalization, the Citarum-Majalaya River
experienced changes for 1.5 years, but then stabilized as no significant changes
were observed from the second to the eleventh year. In this stable condition, the
Citarum-Majalaya River has a capacity of 65 m³/s, which is below ????1,25 , indicating
that flooding will occur if sedimentation is not addressed. |
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