Application of RAGA-SA on Solving Critical Water Depth of Trapezoid Section in Open Channel

Critical water depth is an important hydraulic parameter in open channel hydraulics, which is a key sign of distinguishing the flow state of water in an open channel. The traditional methods for calculating critical water depth of trapezoid section in an open channel are the trial-and-error method, approximate solution and iteration method, whose shortcomings were that the solution process needed a large number of calculations and result with low accuracy. For this reason, the method of Real-coded Accelerating Genetic Algorithm based on Simulated Annealing (RAGA-SA) was built in this paper to solve this problem. The Simulated Annealing algorithm was used to improve the convergence rate and quality of individuals during the late of evolution in RAGA. Practicality and accuracy of RAGA-SA were tested through calculating critical water depth of an open channel with trapezoid section. SA can prevent from a local optimal value in RAGA and made the quality of solution improved at 7%. The results of case study showed that convergence speed of RAGA-SA was faster than SGA and the accuracy was higher than traditional methods to calculate the critical depth at trapezoid section and the result was right. Furthermore, the RAGA-SA can be used in optimization problems in other fields such as determining the water surface curve of a natural channel and contraction section depth of an overflow dam in downstream.