| With the development of our society and economy,the contradiction of water among industry,agriculture and life became increasingly fierce,the pressure of agricultural water continues to increase.However,due to the lack of scientific management in most agricultural irrigated areas,the coexisting phenomenon of water shortage and waste in irrigated areas is inconsistent with the actual needs of crops,and the low efficiency of agricultural water use adversely affects the sustainable development of agriculture.In order to timely meet the realtime water demand of crops in irrigated areas and reduce water loss in the process of channel water delivery and distribution,this paper takes the three-level channel in Sanliuzhai Yellow River Irrigation District of Henan Province as the research object to carry out the research on real-time optimization water distribution technology in medium-sized irrigated areas,in order to provide certain theoretical support for real-time optimization allocation of water resources in canal system in irrigation districts.In view of the problem that the existing real-time irrigation forecast ignored the multiple cropping and continuous cropping in the actual production,the changes of soil water budget in the interval period of crop planting in the next and next seasons were considered comprehensively.Based on the short-term weather forecast and measured soil water data,the real-time irrigation forecast model of crop multiple cropping and continuous cropping was established,and the calculation and modification methods of related parameters in the model were expounded.According to the existing data in Sanliuzhai Yellow River Irrigation District,the model was simulated and applied by taking summer corn-winter wheat multiple cropping from 2014 to 2019 as an example,and the irrigation system schedule was generated.Then,based on the simulated real-time irrigation system,a systematic study was carried out on the reasonable distribution of water flow and water distribution time of the three-level canal system in Sanliuzhai Yellow River Irrigation District.Based on the principle of large system decomposition and coordination,a real-time optimization water distribution model of multilevel channel under the condition of unequal flow of the lower-level channel was established.In this model,the water distribution flow and water distribution time of canal system in irrigation area were rationally planned with the goal of minimizing the total water loss of canal system and the minimum water shortage of subordinate water users,and the model was solved by non-dominated sorting genetic algorithm with elite strategy(NSGA-Ⅱ).Finally,taking the actual water distribution process of the 4th irrigation of 2019 winter wheat in Sanliuzhai Yellow River Diversion Irrigation District as an example,the model was applied to obtain the optimal water distribution scheme.The main research results and conclusions are as follows:(1)Compared with the traditional irrigation system,the real-time irrigation system determined by the real-time irrigation forecasting model of crop multiple cropping and continuous cropping conforms to the law of crop water demand,and effectively saves irrigation water and improves water use efficiency.Among them,the average annual irrigation quota of summer corn and winter wheat during the whole growth period decreased by 31.5% and 12.8%respectively,and the average annual irrigation water consumption of Sanliuzhai Yellow River Irrigation District was saved by 11.38 million m3.The total output of summer maize and winter wheat increased by 2.4%,2.2%,0.8%,2.4% and 6.1%,respectively,and the water use efficiency increased by 13.6%,12.3%,18.3%,11.6% and 15.7%,respectively.This model can provide a theoretical reference for the formulation of water-saving irrigation system under multiple cropping and continuous cropping.(2)Compared with the empirical water distribution plan of irrigation district,the water distribution scheme obtained by using the real-time optimization water distribution model of canal system can meet the design flow of 0.6～1.2 times,and most of the water distribution is more than 0.8 times of the design flow,realizing the large flow of water transmission;In Sanliuzhai Irrigated area of Yellow River Diversion,the total water loss decreased by 25.12%,the water loss rate decreased by 5.43%,and the water distribution time at the head of the main trunk canal,the West Trunk Canal and the Gushitun Trunk Canal decreased by 46 hours,58 hours and 40 hours,respectively.The optimal water distribution scheme solved by the model in this paper can achieve the irrigation goal of saving time and water according to the actual water requirements of crops.The results show that the real-time irrigation forecast considering crop multiple cropping can effectively save irrigation water resources,achieve water saving and yield increase,promote the development of precision irrigation in irrigated areas,and promote the sustainable development of agricultural economy.The water distribution scheme in irrigated areas can realize efficient water distribution in irrigated areas by taking into account the requirements of real-time crop irrigation and the actual operation of canal system,and provide theoretical basis and technical support for realizing agricultural water-saving and modern management in irrigated districts. |
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