| Comprehensive evaluation of water use efficiency in irrigated district is the foundation and key work for comprehensively understanding the operation status and construction level of irrigated district.However,the evaluation of water use efficiency in large-scale irrigated district is characterized by many influencing factors and difficulty in obtaining evaluation index data,The current research is still deficiency.Therefore,it is of great significance for seeking scientific,suitable comprehensive evaluation index system and evaluation method for large-scale irrigated district water use efficiency,which can improve comprehensive evaluation of water use efficiency in large-scale irrigation district,guide scientific innovation and reasonable allocation of regional water resources,improve agricultural water management,ensure the safety of food production and promote the healthy development of the regional ecological environment and regional economy.In this pape,a comprehensive evaluation study on water use efficiency was carried out in the large-scale irrigation areas in Inner Mongolia diverted from the Yellow River,and the main conclusions follow:1.According to the influencing factors of water-use efficiency in irrigated areas,a water-use efficiency evaluation index system consisting of 16 evaluation indexes including water use level,project status,management level,planting structure and ecological environment in the arid area with fragile eco-environment was established.2.The decision tree classification was applied to interpret the area of different surface features and the planting area of crops using remote sensing image data of LandSat8 in Hetao irrigation area in 2016.The confounding matrix is used to verify the accuracy of land use classification and crop classification.The results showed that the overall accuracy of land use classification and crop classification were 86.72%and 83.23%with Kappa coefficient of 0.76 and 0.78.The accuracy of land use classification and crop classification were ideal.The interpretation area of crop using remote sensing is 50.4×104ha with relative error of-4.69%,while the statistical area is 53.5×104ha.SEBAL model was used to calculate the crop evapotranspiration and the crop evapotranspiration in Hetao irrigation area in 2016 was 24.68×10° m°.The penman formula was used to verify the accuracy of the model.Results show that the estimation accuracy of SEBAL model is good.Then the water balance model was used to calculate the utilization coefficient of irrigation water of 0.431 in 2016 in Hetao irrigation area.3.Three evaluation models were constructed,including fuzzy matter-element method based on improved entropy weight,grey relation approximation ideal solution based on improved entropy weight,and principal component analysis and grey relation approximation ideal solution decoupling method,to comprehensively evaluate the water use efficiency of 5 large-scale Yellow River irrigation areas in Inner Mongolia.On this basis,the average value method,the Board method and the Copeland method were used to evaluate the different evaluation results.Result.s show that the evaluation results of the ideal solution method of grey correlation approximation and the coupling method of principal component analysis and grey correlation approximation ideal solution are more reasonable.It is consistent with the actual situation of each evaluation irrigation area.The range and variation coefficient based on principal component analysis and grey correlation approach to the ideal decoupling method is larger,which is more conducive to visually distinguish the irrigation water efficiency level of each irrigation area.4.The 5-grade evaluation standard from high to low water use efficiency in large-scale irrigation areas were determined,and the 5-grade grading standard corresponding to the evaluation index was determined,too.Based on the coupling evaluation value of principal component analysis and grey relational approximate ideal solution,combined with the rank sum ratio method,the variable fuzzy theory analysis method and the set pair analysis method,the water-use efficiency grading evaluation model in irrigation areas were established and the water-use efficiency of five large-scale irrigated areas in Yellow River diversion in Inner Mongolia were graded.Results show that the classification results of the three methods are basically same,and the classification standards of the determined evaluation indicators are basically reasonable.According to the principle that the minority obeys the majority,comprehensively considering evaluation results of three methods,it is concluded that the level of the southern bank of the Yellow River in Ordos is class ?with Higher level.The level of water use efficiency in Hetao irrigation district is class? with above average level.The level of water use efficiency in Unite irrigation area,Madihao irrigation area and Dengkou irrigation area are class ? with middle level,class ? with lower average level and class ? with low level.5.According to the difference between the evaluation level of water use efficiency in each evaluation irrigation area and the grade of corresponding indicators,the evaluation indicators are divided into three categories.According to the characteristics of indicator categories,the main control factors for the improvement of water use efficiency in each evaluation irrigation area are identified.On this basis,the countermeasures for the improvement of water use efficiency in each evaluation irrigation area are proposed. |
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