To describe the complexity of flows accurately around side spillways, a 3D numerical flow model has been tested. In this study 3D numerical model SSIIM2.0 is used to simulate unsteady flows in side spillways in a schematic test channel. Side channel spillways are one of the types of outlet works at dams with wide applications in irrigation, drainage systems, in water and wastewater facilities.

Overflow side, known as cross overflow and overflow sections as a free overflow and flow diversion devices are used in hydraulic engineering. They are made in the side channels or rivers to overflow part of discharge’s crown at the top of the main level. When accidental drop of water happen, sediment transport capacity in the main channel of investment and deposits alluvium for deposition in downstream reduced. Reduce levels, provides back water, additional expansion, and contraction. So the height of the energy loss of the side spillway and overflow discharge increases.

Design discharge to offset increases in the flow of sediment transport. The present confrontation with the overflow stream bed morphology and bed load in a regular channel experiments conducted has not been studied. Results showed that increase in spillway length turbulence in the flow is reduced and morphological changes decrease. Intensity of erosion and sedimentation over time has been increased, in the early minutes of calculations, the rate changes over time in bed was significantly reduced.

The results demonstrate the ability of numerical models SSIIM2.0, to simulate the flow in the side spillway.