Optimization Of Irrigation Pipe Network Under Different Length Scales

Pipe irrigation is a common irrigation technique for developing water-saving irrigation.In order to save the investment of irrigation pipe network,the layout of pipe network,pipe diameter and pump head must be considered in the design of irrigation pipe network.This paper summarizes the related theories of optimal design of irrigation pipe network,and the economy of different pipes is compared.The section flow,inner diameter of pipe and pipe network investments change with pipe network scale were analyzed in this paper,Influence of pipe network layout form,calculation method of pipe diameter and irrigation time to pipe network investment were analyzed too,taking the shape of"?"and"?"as an example.Finally,a method of pipe diameter optimization based on Excel programming is proposed.The main conclusions of this paper are as follows:(1)The unit price of pipeline is expressed as a function of pipe material coefficient,pressure coefficient and pipe diameter,which facilitates the economic comparison of pipelines with different pipe materials and design pressures.The results show that,steel pipe should be used for large diameter pipe,and plastic pipe should be used for small diameter pipe;(2)When the network scale between 0.5~3200 hm~2,the shape of"?"and"?"are different economically.The shape of"?"arrangement is suitable for the case of the pipe network scale of 8 hm~2 or more,both two arrangements can be used under 8 hm~2;(3)The pipe flow rate has a quadratic function relationship with the scale of pipe network;the inner diameter and the pipe network scale are in a power function relationship;the infrastructure fee and the annual cost per unit area are in a power function relationship with the pipe network scale,and the annual operating fee has a quadratic function relationship with the pipe network scale;Full costs are reduced with the increase of the irrigation time;(4)For the calculating the pipe diameter,the one-time investment of empirical formula and derivative method is lower;the annual operating cost of economic velocity method and empirical formula method is less;all things considered,the economical flow rate method is recommended when the pipe network scale is below 2 hm~2,the empirical formula method is used at the pipe network scale is 2 to 800 hm~2,and the derivation method is used at the pipe network scale is 800~3200 hm~2;(5)Excel programming method is economical and convenient,and the optimized results do not need to be adjusted to the standard pipe diameter,and can meet various constraints.