Maryam Abdolahpour - MSc in Hydraulic Structures, Hydraulic Structures Division, Water Research Institute, Tehran, Iran
Reza Roshan - M.Scin Hydraulic Structures, Hydraulic Structures Division, Water Research Institute, Tehran, Iran
Abdorreza Karaminezhad - B.Sc. in Water Resources, Hydraulic Structures Division, Water Research Institute, Tehran, Iran
Hamed Sarkardeh - Ph.D. Candidate in Hydraulic Structures, Hydraulic Structures Division, Water Research Institute, Tehran, Iran

Scouring at downstream of dams is one of the most important issues in designing of outflow structures. In design of flood discharge systems, the goal is passing flow in a way which causes minimum scouring in the downstream of dam body. Otherwise if the scoured hole be more than the predicted value, the dam safety encountered withserious problems. Using physical models is the best way to get ensure about hydraulic performance of the dam. In the present study the scour hole which produced byreleased water jet from the crest spillway of Khersan III Dam was studied by itsconstructed physical model with scale of 1:40. Experimental study has been done to predict scour pattern downstream the dam by using three different flow discharges.Three dimensional scour hole at downstream of the spillway was plotted in different hydraulic conditions. Concluded data also were compared with some empiricalequations. Results showed that there is a good agreement between empirical equationsand experimental data of the present study.

3D Scour Hole; Physical Model; Spillway; Khersan III Dam, Plunge Pool