m pirestani - assistant professor
r riazy - graduate of hydraulic structure

Construction of large dams usually necessitiates the use of flip bucket spillways free falling jets as energy dissipaters using such structures when topographic conditions are well studied is the most economic one among other prevalent dissipaters by addinga tooth slot at the end of flip bucket the effect of different parameters such as flow rate spillway gate opening percetage and tail water depth on downstream bed topographic variations has been investigated some other charaters applied like non uniform bed material with the ratio of sediment mean size d50 anout 2.76 and the ratio of geometric SD is anout 2.11 .

scour , slotted flip bucket , tail water depth , free falling jet