STUDY OF THE EFFECTIVENESS FLOOD AND SEDIMENT CONTROL ON THE OMU RIVER IN SIGI REGENCY

• Main Author: Eko Putranto, Angga
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70690
• Institution: Institut Teknologi Bandung

This study aims to analyze the effectiveness of sediment control structures in the form of sabo and dam consolidation as well as river improvement work in the form of strengthening of cliffs and river normalization in their effect on reducing floods and sediment in the Omu river after the earthquake on September 28, 2018, and the flood incident report on April 28, 2019, and April 26, 2020. Based on the results of hydraulic analysis using HEC-RAS, there was a decrease in the water level even though runoff still occurred at STA-A32 to STA-A35 which is the downstream part of the sabo dam, but at STA-A2 to STA-A15 which is the location of river improvement work (normalization), there was an average decrease in the flood water level of 24.64% and the flow velocity also decreased to an average of 3.66 m/sec. Then based on sediment transport simulations with low flow rates for 12 years under existing conditions, at STA-A2 which is the estuary of the Omu river, a total sediment value of 92,647.22 m3/12 years was obtained. After the construction of the sediment control building and river improvement in scenario-1 can reduce sediment to 82,633.98 m3/12 years or 10.81% with the equation y= 0.3206x2- 7.1263x+50.99 with R2=0.9923, and in scenario-3 it can reduce sediment to 71,175.91 m3 / 12 years or 23.18% with the equation y = 0.365x2-8.6538x+75.834 with R2 = 0.9829. Then by using the 100-year return period flood discharge (Q100) in the existing conditions, a total sediment of 2,566.84 m3 was obtained. After the construction of sediment control structures and river improvement, scenario-2 can reduce sediment to 1,355.91 m3 or 47.18%. and in scenario-4 can reduce sediment to 950.84 m3 or 62.96%. With this, it can be concluded that for flood control, river improvement or river normalization is more effective than using sabo dams, where sabo dams are designed and are more effective for controlling sediment and reducing the speed or energy of flood flow.