Research On The Construction Of Indicator System And Evaluation Method Of Water-Saving Ecological Irrigation Area

Irrigation districts are a key pillar of China’s agricultural development and a production base for commercial grain,cotton and oil,and are extremely important in promoting rural economic growth and improving the ecological environment However,the traditional irrigation district earthen channels could hardly meet the demand for efficient irrigation water transmission,the farmland ditches were fully lined and the side slope masonry hardening works affected the ecological function of the channels,and the irrigation retreat produced many ecological problems,so building water-saving ecological irrigation districts has become a necessary measure to implement the water security strategy and promote the construction of ecological civilization in China.This paper discussed the basic theory of water-saving ecological irrigation districts,and established an index system,grading criteria and evaluation model,and used the Jiaokou Irrigation District in Shaanxi Province as a research example to evaluate its construction and development level.The primary findings are shown below:(1)Through the analysis of the national and international scholars’ findings,and combining the characteristics of irrigation district development,the definition,construction principles and key technologies of water-saving ecological irrigation districts were summarized to build a sustainable and coordinated development of irrigation districts.(2)According to the actual large irrigation areas in China,a set of indicators system for water-saving ecological irrigation areas was constructed using eight selection principles and an optimisation screening model,covering 6 criterion layers and 19 indicator layers of irrigation water-saving system,irrigation area environmental quality,irrigation area ecological resources,socio-economic effects,service management system and human ecological environment,which expressed 85.57%of the information with 52.78%of the indicators,comprehensively reflected the characteristics of water-saving ecological irrigation areas,corresponding to the number of indicators in the criterion layers of 3,2,5,2,3 and 4.The evaluation criteria were determined according to the current national standards and relevant research results,with five levels of"excellent,good,medium,fair and failing" to reflect the development level of irrigation district construction.(3)Analysis of the advantages and disadvantages of subjective and objective weighting methods commonly used in irrigation district evaluation,this paper adopted the genetic hierarchy analysis method for subjective assignment,which generalized the consistency of the judgment matrix to a nonlinear optimization problem and was able to quickly construct the judgment matrix and tested its consistency,and the contribution rate method was used for objective assignment from the structural characteristics of the data itself,and a combined weighting model was established to take into account the sequential and intensity information for the comprehensive weight of each indicator.In the criterion layer,the largest weight was for ecological resources of irrigation area,the smallest was for service management system,in the indicator layer,the concentration of ammonia nitrogen in surface water and irrigation water utilization coefficient had larger weights,while the implementation of "two fees" and the business quality of irrigation management personnel had smaller weights.The combination weight ranking was consistent with the subjective weight ranking,and at the same time took into account the strength information of objective weights,and solved the problem of single adjustment coefficient of subjective and objective weights of traditional combination weighting.(4)In view of the advantages and disadvantages of the existing evaluation models,three evaluation models,including the fuzzy integrated assessment model,the hybrid centroid triangular whitening power function grey assessment model and the improved variable weight object element topologizable model,were improved and established to evaluate the construction status of the water-saving ecological irrigation district in Jiaokou,Shaanxi Province in 2020 respectively,and the results unanimously showed that the development level of the irrigation district construction was in the medium level,its service management system and human ecological environment were in the excellent level,and the rest of the criterion layers were in the medium level,and the constraints of each criterion layer were analysed.Sensitivity studies were performed at the same time using ± 10%,±20%,±30%,±40%and ±50%of the measured values of the indicators to obtain the magnitude of change in the weights and the characteristic values of the rank variables,as well as the main sensitivity indicators when the characteristic values of the rank variables change with the value of a single indicator respectively.Finally,the problems currently faced by the Jiaokou Irrigation District are analysed and corresponding countermeasures were proposed to guide the healthy development of water-saving eco-irrigation district construction.