Study On The Model And Algorithm Of Optimal Arrangement Of Canal System In Arid And Water-saving Irrigation Area

Water-saving irrigation is one of the important symbols of the modernization of irrigation areas.Scientific and rational planning and management of irrigation water resources is of great significance to improve the utilization rate of water resources,ensure food security and achieve sustainable utilization of water resources.With the implementation of supplementary projects and water-saving renovation projects in irrigation districts,the hardware facilities of water supply and distribution and water supply regulation systems in irrigation districts on the northern slope of Tianshan Mountains in Xinjiang have tended to be improved,and drip irrigation and other field water-saving irrigation technologies have matured.However,in the management of canal system in irrigation area,manual water use plan is still used to allocate the amount of water in the canal system.The process is extensive.There are many problems in the process of water distribution,such as large amount of discarded water,long time of water distribution and large loss of water transmission.In view of the above problems,based on the comprehensive analysis of domestic and foreign research results,this paper studied the optimal grouping model of canal system water distribution suitable for water-saving irrigation areas,and studied the efficient and robust model solving algorithm,and Manas irrigation area was selected as the research object,The results obtained in this paper can improve the efficiency of irrigation water utilization and provide a reference for the future optimization of water distribution in canal system.the specific contents are as follows:(1)The method of dividing the combination of rotation irrigation was adopted to formulate the channel water distribution plan,aiming at the problems of unstable water delivery and large amount of discarded water in the existing two-stage irrigation canal system optimal water distribution model based on the mode of "continuous between-group irrigation and inter-group rotation irrigation".The channel optimization grouping model under the condition of changing water distribution mode was studied deeply.The existing water distribution mode was changed to "between-group rotation irrigation and continuous irrigation within the group" and the water distribution flow of each group was adjusted so that the distribution time of lower canals in the same rotation irrigation group is the same.On this basis,the optimal grouping model of canal system allocation aiming at minimizing the leakage loss of water conveyance was established.(2)In view of the complexity of the established optimal water distribution model of canal system and the problem that it is easy to fall into the local optimal solution,particle swarm optimization was improved from two aspects to achieve the solution of the model.On the one hand,by using the particle coding method based on particle position integer operation and the scientific design of fitness function,the difficulty of handling constraints in the model was reduced,and the algorithm was guided to converge to the smallest feasible region space.On the other hand,the idea of crossover and mutation in simulated annealing algorithm and genetic algorithm was introduced into the computational framework of particle swarm optimization to improve the convergence speed and global search ability of the algorithm.(3)Taking the canal system allocation of the Touersangong canals in Manas County Irrigation District in early July 2017 as an example,the study was carried out.The results of water distribution show that the flow rate of upper canal was 1.191 m3/s,the time of water distribution was 3.8 days shorter than the actual time of water distribution.Most of the lateral canals in the process of water distribution meet the requirements of "large flow and short duration",and the results of water distribution meet the requirements of canal system operation and management in irrigation area.Compared with the traditional water distribution scheme,the upper channel inlet gate is adjusted only once during the water distribution period,and the channels in each rotation irrigation group are centralized to simplify the water distribution process of the canal system.The water distribution flow is stable and the water transmission loss is small.The improved algorithm has high calculation accuracy,strong ability to jump out of local optimal solution,and can significantly accelerate convergence speed and improve computational stability.