Study On Optimization Of Dual-Use Irrigation And Drainage Channels In Sanjing Plain Irrigation Area Of Heilongjiang Province

In human production and life,water resources are an indispensable material basis and an extremely important active factor in the natural and social environments.For agricultural development,it is related to the future of a country,and agriculture is the foundation of a country.As the country’s first industry,agriculture is an important guarantee for the maintenance and development of the national economy.In recent years,irrigation and drainage channels in Sanjiang Plain Irrigation Area of Heilongjiang Province is developing rapidly.How to reasonably dispatch irrigation and drainage channels is the central link of irrigation management.The quality of irrigation and drainage dual-purpose channel scheduling directly affects the benefit of irrigation and drainage projects and the increase of agriculture.The main tasks of the plan irrigation are allocating irrigation flow,irrigation time and irrigation water level.Herefore,it is of great significance to study the water scheduling problem of irrigation and drainage channels in irrigation area.The paper takes Yangmu irrigation area of Heilongjiang Province as the research object,studies the irrigation and drainage channels and field channels optimization scheduling of irrigation and drainage,and realizes the real-time optimization scheduling of irrigation and drainage channels based on the rainfall forecast during the growth period.The research contents and results show that:(1)In this paper,MATLAB software is used to establish LSTM model to predict the rainfall in 2021 growth period,so as to realize the real-time optimal operation of irrigation channels.The root mean square error of rainfall prediction in each growth stage is 6.63,6.95,7.34,7.6,8.3,6.82 and 8.34 respectively.The error analysis shows that the rainfall prediction error in the heading flowering period and the yellow maturity period is relatively large,but the rainfall error is within the allowable error range,and the overall prediction effect is good.Based on the rainfall prediction of LSTM model,the rainfall of each growth stage of crops in the Yang Mu irrigation area in 2021 was predicted.The predicted values are 20.6 mm,37.4 mm,92.8 mm,21.1 mm,6.2 mm,22.0 mm and 10.8 mm respectively.According to the predicted rainfall data,the irrigation schedule is formulated to prepare for the real-time optimal scheduling of irrigation and drainage channels.(2)Based on the basic situation of irrigation and drainage channels in the irrigation area,the paper analyzes the effects of the flow and water level of the irrigation and drainage channels on the benefits of waterlogging.It is concluded that the irrigation water level is always higher than the drainage water level during the crop growth period.Part of the stagnant water cannot be eliminated,and the retention of precipitation causes the crops to suffer from waterlogging for too long,and the benefits of waterlogging are reduced.When the irrigation water level rises,the drainage benefit will also decrease.(3)In this paper,the multi-objective optimal operation model of trunk and branch canals is established with the objectives of less water loss of irrigation and drainage dual-purpose canals,minimum fluctuation of water flow of upper canal and maximum benefit of irrigation and drainage engineering.The real-time irrigation water quantity,irrigation flow,irrigation time and irrigation water level were taken as constraints.The non-dominated sorting genetic algorithm with elite strategy is used to optimize the scheduling model to solve the water delivery flow,water delivery time and corresponding gate opening height during irrigation and drainage,drainage flow,drainage time and gate opening height during waterlogging.After optimization,the water delivery time of the canal is relatively shortened during crop irrigation,and the water delivery flow is uniform and stable during the water delivery process.During the period of crop drainage,the gate can be opened on time,which can ensure that the surplus water can be discharged within the duration of crop flood resistance.When the irrigation and drainage requirements are satisfied,the actual water conveyance scheme of irrigation and drainage dual-purpose channel is determined.(4)In order to achieve the overall scheduling of regional channels,this paper studies the optimal scheduling of field channels in irrigation area based on the results of optimal scheduling of backbone channels.In order to minimize the difference of continuous irrigation time among different irrigation groups,the optimal scheduling of field canal water delivery is divided into irrigation groups.The irrigation time and process of irrigation group are solved with the constraints of irrigation cycle,actual water delivery flow and time of upper canal.After optimization,the combination of rotation irrigation groups with the smallest difference of continuous irrigation time was obtained,and the water intake flow of each rotation irrigation group was less than the upper channel limit flow.According to the irrigation process diagram of each field channel obtained from the division model of rotation irrigation group,the irrigation process of the ditch and agricultural channel is stable in the whole irrigation cycle,which makes less water loss of each channel,and it is conducive to the management of irrigation channel scheduling.