Hydraulic flow and downstream scouring behavior on spillway system of Surumana Dam

Surumana Dam is designed to meet various needs of water in Donggala, Central Sulawesi, and its surroundings. It is planned to be equipped with a side channel spillway, which sequentially consists of an approach channel, side spillway, side channel, transition channel, slide channel, energy absorber type USBR II, and an escape channel to the main river. The safety of the spillway system design, which affects the overall safety of the dam, is determined by the hydraulic behavior. This study aims to investigate the hydraulics flow in the side spillway system and scouring in downstream due to the flood discharge through the spillway dam by using a physical model test in the laboratory with a scale of 1:60. The model was used to measure the hydraulic parameter as velocity, depth, and pressure, under Q₁₀₀, Q₁₀₀₀ and Q_PMF discharge. The result of the analysis showed the hydraulic flow behavior, especially in the phenomenon of damping the energy of water flow in stilling ponds (energy damper) and scouring in the downstream river bed. The results of this hydraulic model test provided a better picture of the flow behavior of the spillway system in terms of energy dissipation and scour.