Page - 1067 - in Book of Full Papers - Symposium Hydro Engineering

Figure 7. Final design of new spillway’s stilling basin One-dimensional numerical modelling of the river flow showed that the difference between water stages at low and high floods is significant. Therefore, the governing condition for the basin design corresponds to a downstream water level that results from the full discharge through the new spillway, with the existing spillway closed. In figure 8, the energy dissipation is shown at a discharge of 475 m3/s merely from the new spillway. Due to the low downstream water stage, the end-sill location should be placed as close as possible to the river course. A too large distance would not help hold up the basin water level and form a proper hydraulic jump, as the high- velocity outflow from the basin pushes away the water in the river. The end sill location is, to some extent, limited by the terrain and the rock quality of the river bank. End sill 1067