Flood discharge safety of high-head and large-capacity spillway tunnels is important for the hub operation

and the layout method of the spillway tunnels is the key influencing flood discharge safety. Currently

the layout of the spillway tunnels is mainly demonstrated by model tests

and there is still alack of systematic evaluation indicators. This paper presents the evaluation index by river capacity for the spillway tunnels

and constructs the layout method of the spillway tunnels based on the coordination of energy dissipation and scouring. Furthermore

the rationality of the layout method has been verified by the energy dissipation schemes of many 300-meter high dams.