Experimental Investigation of Energy Dissipation in Ogee Spillway Using New Distributions of Dissipation Blocks

Abstract

Ogee spillway is the most important structure used to get rid of excess water during flood. Scouring phenomenon occurring in the downstream region due to high energy dissapation is an envitable. This study aims to reduce the amount of scour occurred at the downstream stilling basin of the ogee spillway by using three dissipation energy blocks namely as baffle, triangle and stepped blocks. A new distribution was proposed for each type of dissipated block, which varied between one row, two rows, and three rows. The flow and scour experimental tests were carried out under Froude numbers ranging from 2.5 to 8.5. During the tests, sequent depths and transverse velocities distribution were measured. The results showed that the used blocks appeared with good results in minimizing flow velocities and sediment scouring within the stilling basin in accordance with proposed distributions, especially with the range of Froude number 4.5-8.5. Also, The stepped block is characterized by reducing the flow velocities compared to the baffle block and triangle block, as it can be seen that there is a decrease in velocities up to 0.85% for all used distributions (A1, A2, A3, B1, B2, and C1).