Research On Suitability Evaluation And Optimal Design Of Irrigation District Water Conveyance System

China is short of water resources,water resources are distributed unevenly in time and space,and water resources per capita is insufficient,water shortage has become an important factor restricting China’s economic development and social progress.Irrigation district is the main aspect of China’s agricultural water,the sustainable development of irrigation is an important factor to decide the development of irrigated agriculture in our country.At present,large and medium-sized irrigation districts in our country generally have run,take,drop,leakage and other engineering problems,rebuilding and water-saving work is imperative.At the same time,irrigation water loss mainly occurred in the water system,has become an important part of restricting the sustainable development of irrigation.Irrigation water conveyance system suitability reflects the suitability between irrigation development and irrigation water conveyance system,therefore,establish the evaluation index system and evaluate the suitability of irrigation district water conveyance system from the perspective of the sustainable development of irrigation districts,and then improving the efficiency of agricultural water use,reducing the proportion of agricultural water,can provide new ideas for rebuilding and water-saving work,promote sustainable development of the irrigation district and promote economic and social development.The water conveyance system suitability evaluation of Hamatong irrigation district,Woken River irrigation district and Jiangchuan irrigation district is conducted in this paper,and the channel section and layout optimization of Hamatong and Woken River irrigation district are also elaborated.The main research contents and conclusions are as follows:(1)The paper analyzes the suitability of irrigation water conveyance system based on the existing research and the actual situation of the irrigation district,selects the channel lining rate,investment channels for the construction unit,irrigation area,irrigation water use per unit area,irrigation efficiency,per capita income of farmers,the mining rate of groundwater,the unit length of channel irrigation area and water channels covering rate as the evaluation index to construct the irrigation district water conveyance system suitability evaluation index system,and determine the weight of evaluation index using AHP and entropy method.Use fuzzy matter-element model,TOPSIS model and fuzzy comprehensive evaluation method to evaluate water system suitability of Hamatong irrigation district,Woken River irrigation district and Jiangchuan irrigation district,according to the established evaluation index system and determine the suitability level.The evaluation results show that the water conveyance system suitability of Hamatong irrigation district is Ⅱ,and the water conveyance system suitability of Woken River and Jiangchuan irrigation district are Ⅲ.(2)According to the present situation of the water conveyance canal layout,in order to optimize the layout of irrigation canal,the shortest path of the channel is taken as the objective function.To the Hamatong irrigation district it is divided into without considering the current situation of the channel and taking the status quo into account two situations.The discrete firefly algorithm is used to solve the problem,and the channel length is reduced by 19% and 1.2% respectively,the optimization effect is obvious.The channel length is reduced by 19% to the Woken River irrigation district.At the same time,to verify the effectiveness and superiority of the discrete firefly algorithm in solving the problem of channel layout optimization,the layout optimization process of water distribution channel in irrigation area is compared among discrete firefly algorithm,particle swarm optimization and genetic algorithm.The result shows that compared with the genetic algorithm and particle swarm optimization algorithm,the discrete firefly algorithm has faster convergence speed and stronger robustness.(3)In order to optimize the main channel cross section of Hamatong and Woken River irrigation district,the objective function is determined to minimize the area and the velocity error of the channel,the velocity and channel width depth ratio are taken as the constraint condition.The optimization result shows that,the area of the channel is reduced on the basis of the constraints.to the Hamatong irrigation district,the second main canal channel cover area reduced by 15.89%,the third main canal channel cover area reduced by 5.1% and the fourth main canal channel cover area of reduced by 6.5%,to the Woken River irrigation district,the Lianhe main canal channel cover area reduced by 5.1% and the Sanhe main canal channel cover area reduced by 5.1%the optimization effect is obvious.