Water Resources Simulation And Optimization In Canal And Well Combined Irrigation District Based On NSGA-?

Due to the influence of terrain and climate,although the total amount of water resources in China is abundant,the spatial and temporal distribution is uneven,especially in the northsouth distribution.China is a traditional large agricultural country.In order to ensure food production,it has been vigorously developing irrigated agriculture for many years.Therefore,agricultural water consumption is large,especially in arid and semi-arid areas in the northwest,where agricultural water consumption accounts for 70%.The misalignment of the spatial distribution of land and water resources makes large irrigation areas decisive for high and stable agricultural production in the north.The sustainable use of water resources in irrigation areas is the basis for sustainable agricultural development and plays an important role in economic and social development.The combination of canal and well irrigation modes can effectively improve the irrigation water utilization efficiency of the irrigation area.By determining the appropriate ratio of canal and well water use,the groundwater level of the irrigation area can be controlled to maintain a reasonable range.However,in recent years,due to the shortage of water resources,unreasonable water allocation in canals and wells,and imperfect management systems,the groundwater extraction in many irrigation areas has been too large,resulting in an imbalance in mining and replenishment,and the groundwater level has continued to decline,which has led to a series of ecological and environmental problems.How to reasonably use the surface water and groundwater resources in the irrigation area and control the groundwater in the irrigation area to maintain a reasonable interval is an urgent problem to be solved in the channel-well irrigation area.Constructing water resources simulation and optimization model to optimize the allocation of water resources in irrigation districts based on surface water and groundwater is an important way to solve water problems in irrigation districts and achieve sustainable and efficient utilization of water resources in irrigation districts.The current research trend at home and abroad is to try to combine the simulation model and the optimization algorithm from multiple aspects to construct a new water resources simulation optimization model.Due to the complexity of water resources simulation and optimization models,heuristic optimization algorithms currently rely on genetic algorithms,ant colony algorithms and particle swarm optimization algorithms.These algorithms sometimes need to frequently call and run simulation models.With the optimization model optimization With the increase of goals,the simulation optimization model is easy to reduce its practicality due to the long running time.Therefore,there is an urgent need to improve the running speed of the simulation model and the solution efficiency of the optimization model through a variety of ways.In this study,a typical representative canal irrigation area in the north—Jinghui canal irrigation area in Shaanxi Province was selected.Based on Python language,the canal and well combination was constructed by tightly coupling the current multi-objective genetic algorithm NSGA-? and groundwater numerical simulation software Flo Py The optimization model of water resources simulation in the irrigation area has important theoretical significance and application value for solving the shortage of water resources in the irrigation area,realizing the sustainable use of water resources in the irrigation area and the virtuous cycle of the ecological environment.The main conclusions of the study are as follows:(1)Generalized the water circulation system in the irrigation area,pointing out that precipitation and air temperature are the natural factors that have a greater influence on the water circulation in the irrigation area;the amount of channel irrigation diversion,groundwater exploitation,and land cover type are the most influential human factors.And calculated and analyzed the effective rainfall in the irrigation area,the annual irrigation water demand of the main crops at various levels and the net irrigation water demand.(2)According to the specific underlying surface conditions of the irrigation area and land cover data,the crop planting structure and spatial distribution are obtained.Combined with the annual irrigation system of different levels in the irrigation area,Flo Py is used to set different source and sink for each grid in the groundwater numerical simulation model grid This item makes the numerical simulation model of groundwater flow in the irrigation area more in line with the reality of the irrigation area.(3)Select the maximum water productivity as the social goal,the maximum total economic benefit of the irrigation area as the economic goal,the minimum irrigation water loss as the resource goal,the minimum Gini coefficient of the drainage channel of each administrative area as the fair goal,and the groundwater level provided by the coupled groundwater numerical simulation model Fluctuation target construction Canal and well combination multi-objective water resources simulation optimization model in irrigation area,using Flo Py and Pymoo written in Python language,using computer memory to share data,greatly improves the calculation speed and solution efficiency.The tight coupling of the simulation optimization model was achieved,and the NSGA-? algorithm under the Pymoo framework was used to optimize the solution.A set of water resources optimization allocation schemes for different levels of Jinghuiqu Irrigation District was obtained.(4)The optimal optimal allocation plan shows that reasonable adjustment of the diversion of canal irrigation and well irrigation in the different irrigation seasons of each administrative region can slow down the fluctuation of the groundwater level during the year and keep the groundwater level of the irrigation area within a reasonable interval.The water consumption ratio of canals and wells in the orchards and cultivated land in the irrigation area is 1.63 and 1.45 in the high water year,1.46 and 0.93 in the normal water year,and 1.66 and 1.62 in the extremely dry water year.In the water year,the groundwater level drops,and the goal of regulating and storing the groundwater is achieved.