Study On Optimization Design Method Of Gravity Drip Irrigation Pipe Network System With Two-Level Pivot

Gravity drip irrigation is a drip irrigation technology that uses the natural drop to form water head required for irrigation,which has significant water saving,energy saving and increasing production.In recent years,gravity drip irrigation technology has been widely applied in our country.The construction scale of project is increasing,and the independent field drip irrigation system has been developed into large-scale drip irrigation system combined with multiple field drip systems.A two-level drip irrigation system generally uses a first-level pivot as the water source.The water is delivered to each second-level pivot in field subsystems through the main water distribution pipe network system(MWDPNS).Subsequently,it is irrigated to farmland through field drip irrigation pipe network subsystems(FDIPNSs).In the past,most of optimization design for drip irrigation pipe network focused on the research of the independent field pipe network system,but did not study the optimization design of drip irrigation pipe network with two-level pivot.Therefore,in this paper,the optimization design method of gravity drip irrigation system with two-level pivot was proposed,and the construction scale optimization method of field pipe network project of gravity drip irrigation system was studied.The main results are as follows:(1)By analyzing the optimized design points of gravity drip irrigation system with two-level pivot,the mathematical model for simultaneous optimization of the pipe network layout and pipe diameter selection in two-level gravity drip irrigation system was established,and the method and steps based on atom search optimization(ASO)was proposed.First,all the FDIPNSs are optimized;then,the MWDPNS is optimized with the optimization results of each subsystem as the basic design parameters.For the MWDPNS,the other available water diversion nodes,except the second-level pivot nodes,are added.By comprehensively considering the topological and hydraulic constraints,the topology design and pipe diameter selection are simultaneously optimized when the selection of the water distribution nodes is uncertain.For the FDIPNSs,the field width is regarded as a linear piecewise function of the field length,and the constraints such as the pipeline layout,flow velocity,discharge,pressure,and rotational irrigation scheme are considered.The model can realize the optimization design of most irregular shaped fields.(2)Taking the gravity drip irrigation pipe network project with two-level pivot in Xinjiang,China as an example,the effectiveness and superiority of the optimization model and algorithm proposed in this paper were verified.In addition,ASO was compared with genetic algorithm(GA)and particle swarm optimization(PSO).The optimization results showed that the optimal investment based on ASO,GA,and PSO were reduced by 18.37%,16.45%,and 16.85%,respectively,compared with the investment of the original design scheme.The optimal investment of ASO was the lowest and the convergence speed was the fastest.Furthermore,ASO is simple and easy to implement.The proposed optimization method has good application value for the pipe network optimization design of two-level gravity drip irrigation system with multiple drip irrigation subsystems.(3)Considering the influence of construction scale of field pipe network project of two-level gravity drip irrigation system on investment,a mathematical model for the construction scale optimization of field pipe network project was established and solved by ASO.In this model,the objective function was the lowest comprehensive cost per unit area considering the service life of the project,and the constraints such as pipe network layout,pipe diameter,selection of head pivot and pressure were comprehensively considered.Taking the gravity drip irrigation system with two-level pivot in Xinjiang,China as an example,this method was used to calculate the optimal scale of its field pipe network project.The results showed that the optimal project scale of the project was 89.00 hm~2.The comprehensive expense per unit area of the optimal project scale was lower than 23.02%that of the typical pipe network scale in the original design.The proposed optimization method provides a new idea and optimization calculation method for the scale division of gravity drip irrigation system.(4)Using the graphical user interface(GUI)of MATLAB,all parameters that need to be set in drip irrigation system and ASO were designed as"editable text"to realize visual operation.The auxiliary optimization design software for gravity drip irrigation pipe network with two-level pivot and the optimization calculation software of field gravity drip irrigation pipe network system were developed.The example test showed that the two sorts of software developed in this paper have simple operation,simple and beautiful interface and complete functions.They can be used by designers to optimize the gravity drip irrigation pipe network system with two-level pivot quickly and efficiently.