ABSTRACT
This chapter provides the flow conditions at river diversions and methods for predicting their performance. Flow conditions in closed conduits that serve as river diversions during construction vary markedly with the magnitude of the discharge. For open channel flow, the capacity is dependent upon the entrance geometry, the slope and length of the conduit, and the outlet condition. In river diversion tunnels, three different flow conditions, open channel flow, part-full flow and full flow, may occur depending on discharge. The flow conditions in a tunnel have to be established before carrying out detailed calculations. For open channel flow, the discharge is a function of the outlet flow condition, the slope and the length of the conduit. The discharge for the full flow can be calculated by well established methods. In order to speed up the process of calculation, a criteria of low limit flow is presented.
