Weir as a hydraulic structure with an upstream and downstream flow pattern has been of key importance to many researchers in the field of civil engineering. Energy dissipation is considered a challenge that forces researchers to make it high priority. The aim of this study is to examine the impact of the use of different shapes as obstacles at the downstream of a weir on the scour hole depth downstream of its structure. The speculated results will then be compared with actual measurements to present the efficiency of CFD techniques to current actual hydraulic-structure problems. The flow 3-D package will be considered as the simulation tool in this study. In order to achieve the highest energy dissipation, thus, the minimum scour depth at the downstream, nine various models of different shapes of weirs were numerically and experimentally analyzed. The shapes of the weir models were optimized by numerical simulations then they were physically tested in laboratory experiments. The models have a width of 0.8m and a height of 0.59m, while their lengths range from 0.72 to 1.12m. The bottom of the channel was covered by a sand layer of 0.2 m thickness with a grain gradient rate of 0.002m. Three different discharge values of 0.015, 0.02 and 0.025m3 s-1 were utilized in the experiments. The experimental and numerical simulation results showed similarities with the maximum depths of scour for all analyses were noted to be between 0.003m and 0.012m. Six models have been explored, the model SU3 was found to demonstrate the minimum scour depth ranging from 0.003 to 0.005m under all flow conditions, In this model, the scour has settled during the first (15) minutes of experiment for the first and second discharges (0.015, 0.020 m3s-1) to be (0.018, 0.02 m) (Table 2) while the scour has settled for the third discharge (0.025 m3s-1) after four hours to reach (0.03 m), therefore, presenting the best performance in terms of energy dissipation.