Evaluation Of Water Cycle And Crop Growth Interaction Under Changing Environment In Typical Irrigation District

Affected by human factors and environmental factors,groundwater funnels appeared in many places in north China,and the temperature continued to rise,which has a negative impact on local agricultural development.To make full use of local natural resources,optimize agronomic measures,and achieve sustainable development of high yield in north China,it is necessary to analyze and evaluate the impact of groundwater and climate resources on crops,and further optimize crop irrigation systems.In this paper,a main economic crop in the Shijin Irrigation District–summer maize was selected as the research object.The main research achievements were depicted as follows:（1）The fluxes and variations of this area were analyzed according to the bivariate comprehensive model of water cycle in Shijin Irrigation District.It can be seen that the average irrigation water and rainfall infiltration replenishment in Shijin Irrigation District is insufficient to meet the total consumption of groundwater,resulting in a downward trend of groundwater depth.Agricultural water competition and changes in reservoir inflow lead to a decrease in irrigation water consumption,and the vertical evapotranspiration increases slowly.（2）Based on the AquaCrop model,the effects of groundwater depth on summer maize growth were evaluated.The results showed that the suitable groundwater depth of summer maize in Shijin Irrigation District was 1.5-2.0m,the optimal groundwater depth was 1.5m,and its affection can be negligible when the depth exceeded 3.5m.（3）The effects of climate change on summer maize yield were quantitatively analyzed by combining the climate scenario RCP4.5 and AquaCrop model.The results showed that under the RCP4.5 scenario,the future yield of summer maize in Shijin Irrigation District was mainly reduced,but the yield change showed an upward trend.When the direct impact of CO₂ is not considered,the yield change ranged from–6.72%^–3.04%,when considering the direct impact of CO₂,the yield change ranged from–4.04%⁺0.11%.（4）The irrigation schedule of summer maize is optimized with the aim of maximum net profit of single water.The results showed that in wet year,the irrigation water was not needed.In normal year,summer maize can be irrigated at seedling and jointing stage respectively with an irrigation quota of 25mm,the total amount irrigation is 50mm,and the summer maize yield reaches a maximum value of7.23t/hm²,the water use efficiency is 2.250kg/m³.In dry year,summer maize can be irrigated at seedling,jointing and flowering stage respectively with an irrigation quota of 46.6mm,the total amount irrigation is 140mm,and the summer maize yield reaches a maximum value of 7.198t/hm²,the water use efficiency is 1.992kg/m³.