Optimal Design and Hydraulic Performance Improvement of Labyrinth Spillway using Cuckoo Search Algorithm

One of the appropriate procedures to increase discharge capacity of spillway in dams, particularly when increase of overflow width is not possible, is using labyrinth spillways. Due to the fact that a considerable portion of costs of dams is allocated for construction of spillways, the search for methods to optimize these structures becomes important. In the present research, the Cuckoo Search (CS) algorithm has been used to find the best geometry of the trapezoidal labyrinth spillway. For this purpose, concrete volume of the spillway was considered as objective function. Aslo, the spillway design considered different hydraulic constraints. Optimal parameters of this algorithm were selected by performing sensitivity analysis. Then, CS was run randomly for 15 iterations. The coefficient of variation and convergence speed obtained from random runs for the proposed algorithm were equal to 0.00001 and 1000 iterations, respectively. Finally, minimum value of the objective function of the proposed algorithm was compared to the results obtained from spillway design and the results of Genetic Algorithm (GA) and Differential Evolution (DE) proposed in the previous studies. It was found that the proposed spillway dimentions using CS resulted to 38.91% less concrete with respect to the real prototype. In the proposed model, other than reduction of the spillway concrete volume, the overflow discharge of the spillway was increased. On the other side, concrete volume reduction obtained by CS was 12% less than classic optimization algorithms (GA and DE). Considerable decrease (more than 1/3) in the volume of concrete in the proposed spillway indicates high ability of CS in solving the problems of optimizing spillways and the necessity of using it.