Hydraulic Calculation And Optimal Design For Subsurface Drip Irrigation Network

Becourse China was a water-scarcity country, that has influenced seriously our national economy and society's sustainable development.The modern water-saving irrigation techniques alleviated the shortage of water resources contradictions, but the water-saving irrigation economic investment higher, disadvantage in this technical expansion and exaltation. Subsurface drip irrigation is an efficient way of the water-saving irrigation Hydraulic calculation of pipe network redounds to investigating the hydraulic characteristic of the subsurface drip irrigation network. Design optimization of the SDI system can effectively reduce the overall investment of the system. It is of great significance to promote further the development of subsurface drip irrigation.On the base of analyzed the technology developments of the subsurface drip irrigation and reviewed hydraulic calculation of pipe network and the optimization theory of optimum planning of SDI, the main content of this paper is as following:Firstly, analyze the hydraulic calculation of SDI networks and the evaluation criteria and the system condition to establish optimization model. Through the analysis the hydraulic characteristic of the circular network pipe, to study along the regulation flood peak difference and the node current capacity computation of the subsurface drip irrigation circle network, to lay the foundation for proposing the system conditions that restraint the pipe network optimizal model.On the base of using for reference of models which is founded by the elders, through taking annual minimum cost as the objective function, taking the cost formula of pipe network as the foundation, taking diameter as optimization variable, the nonlinear programming models by working in turn is founded. According to the model, the solution of technology & economy and flow bounds approach is detruded.Secondly, stochastic non-linear programming by random irrigating are presented to optimize the diameters of network. In SDI, the mode of working in turn did not concern the different of crop, so the paper take net benefit as the objective function, a new model for optimal design of SDI network by random irrigating is developed, this can be used in choosing reasonable irrigation schedule and saving much more investment.Thirdly, the author introduced the theory of genetic algorithm and solved the two models which have the characters of many discrete and mixed variables and nonlinear by genetic algorithm. Furthermore, the author took the calculation and analysis by combing each model with living example and get satisfactory result. All these proved that these models and solution had both notable economic benefits and highly practical value.