| Our country is a big food production country,promoting irrigation agriculture has been the general focus of agricultural development for a long time,along with the social economic level and the increase of people’s happiness,new requirements for scientific crop planting.In recent years,due to the rapid expansion of the planting area of corn and other crops in some areas of north China,the irrigation water consumption has increased significantly,resulting in serious overextraction of groundwater,forming a large area of falling funnel,and causing a series of ecological and environmental problems.The new maize variety TK601 is suitable for planting in Erdos City,Inner Mongolia and spring maize planting area in northern Shaanxi.Due to the lack of local surface water sources,irrigation mainly relies on groundwater mining.The ecological environment in these regions is relatively fragile,and large-scale planting will inevitably have an impact on groundwater ecological environment.Therefore,the influence of irrigation on regional groundwater dynamics must be taken into account.Therefore,when the new maize variety TK601 is widely promoted in arid and semi-arid well irrigation areas,the influence of irrigation on maize yield and regional groundwater should be taken into account to formulate appropriate irrigation system.In order to explore the irrigation system that considers the sustainable utilization of groundwater resources and the negative impact of irrigation on ecological environment in arid and semi-arid areas,as well as the maize yield,this study constructed the maize growing crop model based on AquaCrop.Considering the actual irrigation situation in the experimental area,the typical scenario of groundwater extraction for maize drip irrigation was generalized.Based on FloPy,a groundwater numerical simulation model was constructed to quantitatively evaluate the influence of irrigation on groundwater level,and 100 non-bad solutions were obtained by using NSGA-Ⅲ,a multi-objective genetic algorithm in Pymoo framework,aiming at the variation of groundwater level and the yield.Ten schemes with different trends were selected based on the comprehensive consideration of the yield and the influence on groundwater dynamics.Finally,the entropy weight TOPSIS method is used to recommend irrigation systems in different hydrological years,and the variation of groundwater level under different aquifer permeability coefficients is quantitatively assessed.The following main research results were obtained:(1)Field drip irrigation experiments were carried out to obtain the yield data of new maize varieties TK601 under different water and fertilizer treatments.In low water low fertilizer,water fertilizer,high water high fertilizer and other ten different water fertilizer treatment,corn measured the highest per mu yield of 813.88kg,the lowest per mu yield of668.66kg,the average per mu yield of 794.32kg,which high water and high fertilizer average per mu yield of 797.74kg,water fertilizer average per mu yield of 778.57kg,The average yield of low water and low fertilizer per mu was 678.89kg.(2)The TK601 maize growing crop model was constructed based on AquaCrop-OSPy,and the parameter calibration and model verification were carried out.The results of crop model parameter calibration showed that the yield fitting degree was the best under W1N1treatment,and RMSE,d,NRMSE and R~2were 65.17 kg/hm~2,0.68,1.49%and 0.78,respectively.Under W2N2 treatment,RMSE,d,NRMSE and R~2were 5.22%,0.99,13.16%and 0.93,respectively.The biomass of upper corn field under W3N3 treatment had the highest degree of fitting,RMSE,d,NRMSE and R~2were 88.27kg/hm~2,0.88,15.33%and0.95,respectively.The results showed that AquaCrop-OSPy could accurately simulate the dynamic change process of yield under different irrigation scenarios.The simulation results fit well with the field measured results and both meet the accuracy requirements.(3)The hydrogeological conceptual model under corn drip irrigation scenario was generalized,and the numerical simulation model of groundwater under corn drip irrigation scenario was constructed based on FloPy.FloPy can be used to quickly construct,run and modify the groundwater numerical simulation model,and can be easily coupled with the optimization algorithm to construct the simulation optimization model.The results of the coupled model show that:Under the condition of stable precipitation in normal water years,the irrigation mode of corn planting in the experimental area in dry water years was more dependent on groundwater,which showed that during the growth period of corn,the groundwater level of corn growing at seedling stage,jointing stage and grouting stage was0.6m,1.1m and 0.5m,respectively,and the yield decreased by about 53.4kg/mu.The groundwater table distribution of aquifer permeability coefficient k=5m/d was compared.When the permeability coefficient k=10m/d,there were great changes in the groundwater table at each stage of maize growth:seedling stage:1.1m,jointing stage:0.9m,spinneret stage:1.8m,grouting stage:1.9m,maturity stage:1.9.When the permeability coefficient is k=15m/d,the change of groundwater level is as follows:seedling stage:2.1m,jointing stage:2.6m,silking stage:2.6m,grouting stage:2.0m,maturity stage:2.4m.(4)The simulation results of the coupling model better meet the needs of different decisions,and can provide reference value for different decision-making departments.The determined irrigation system totals 10 irrigation times,2 irrigation times each from seedling stage to silking stage,and 1 irrigation time respectively at grouting and maturity stage.The results showed that compared with the irrigation system that only considered the yield,the recommended irrigation system could lead to a slight decrease in corn yield of about 45.36kg/mu.However,during the maize growth stage,filling stage and maturity stage,the decrease of groundwater level was reduced by about 1.2m and irrigation water consumption was reduced by 255m~3/hm~2.The effect of irrigation on groundwater is reduced. |
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