Diversion canal to decrease flooding at Kemuning river, Sampang district

Abstract

Flooding occurs when rain runoff water cannot be accommodated by a river, due to the flow of water that exceeds its drainage capacity. Flooding can occur anywhere, one of which occurs in the Kemuning river, Sampang Regency. The existing ag factor of the river profile that is experiencing siltation is also a cause of flooding, especially in the rainy season. This study aims to reduce flood discharge in the Kemuning river by planning a diversion channel as a solution using HEC HMS and HEC RAS modeling. Diversion channel is a divider discharge channel or shortcut to reduce flood discharge in rivers that flow directly into the sea. In this study three alternative solutions are planned, alternative 1 is planned to use a rectangular cross-section, alternative 2 is planned to use a trapezoidal cross-section and alternative 3 is planned to use a trapezoidal cross-section and adding and raising existing river embankments. The results of the analysis and planning showed that the flood discharge plan for the 25 year return period in the HEC HMS modeling was 781.9 m3/sec. The results of the HEC RAS modeling with flood hydrograph input during the 25-year return period, Kemuning river conditions overtopping at all stations as high as 1-4 m. From the trial and error results in the HEC RAS modeling, the maximum capacity of the Kemuning river is 90 m3 / second. Based on the maximum capacity of the Kemuning river, alternative diversion channels 1 and alternative 2 are planned to accommodate flood discharge of 681.9 m3 / sec. An alternative diversion channel 3 is planned to only discharge flood discharges of 300 m3 / sec by adding and raising embankments on the Kemuning river. All alternative diversion channel planning can reduce flood discharge by a percentage of 88.5% for alternatives 1 and 2, 38.4% for alternative 3. Based on the maximum capacity of the Kemuning river, alternative diversion channels 1 and alternative 2 are planned to accommodate flood discharge of 681.9 m3 / sec. An alternative diversion channel 3 is planned to only discharge flood discharges of 300 m3 / sec by adding and raising embankments on the Kemuning river. All alternative diversion channel planning can reduce flood discharge by a percentage of 88.5% for alternatives 1 and 2, 38.4% for alternative 3. Based on the maximum capacity of the Kemuning river, alternative diversion channels 1 and alternative 2 are planned to accommodate flood discharge of 681.9 m3 / sec. An alternative diversion channel 3 is planned to only discharge flood discharges of 300 m3 / sec by adding and raising embankments on the Kemuning river. All alternative diversion channel planning can reduce flood discharge by a percentage of 88.5% for alternatives 1 and 2, 38.4% for alternative 3.