Seite - 694 - in Book of Full Papers - Symposium Hydro Engineering

Fig. 8. Upper Cisokan spillway model with discharge of Q100yrs Based on the experiment, the deepest local scour reaches –3 m measured from elevation El. + 729.00 m, located at the toe of downstream left and right wing walls as can be seen in Figure 9. This scouring phenomenon may harm the structure, therefore downstream protection is needed. Fig. 9. Scouring condition at downstream of spillway (Scenario 1) To minimize the scouring effect at downstream of the spillway, the kinetic energy dissipation needs to be optimized using stone riprap. Considering available material on site, stone riprap protection is recommended to use as downstream protection because there are many stone quarry. Scenario 2 was conducted at the 694