井渠结合灌溉对地下水时空分布及空间相关性影响OA

The eastern Shijin Irrigation District has long employed a conjunctive well-canal irrigation model.To investigate the impacts of irrigation activities on the spatiotemporal distribution and spatial correlation of groundwater,this study analyzed groundwater depth data from 64 monitoring wells(covering both deep and shallow aquifers)during 2018-2023 using spatial interpolation techniques.The research focused on elucidating the interannual and intra-annual evolution patterns of deep and shallow groundwater in the irrigation area,along with evaluating the influences of rainfall and irrigation practices on spatiotemporal groundwater depth variations.Key findings include:①Ordinary Kriging with a Gaussian function demonstrated superior interpolation accuracy,establishing it as the optimal model for groundwater analysis in the eastern Shijin Irrigation District.② Spatially,shallow groundwater depth generally exhibited lower values in the north and higher values in the south,showing a gradual increase from north outward.Deep groundwater depth displayed an opposite pattern,with lower values in the southeast and higher values in the northwest,increasing gradually from southeast to northwest.Temporally,during 2018-2023,shallow groundwater depth showed an increasing trend with an average rise of 1.36 m,while deep groundwater depth demonstrated a decreasing trend with an average reduction of 2.5 m.③ Shallow groundwater in the study area is predominantly brackish,with its intra-annual dynamics significantly influenced by rainfall cycles,showing average fluctuations of 1.42 m in brackish zones and 18.91 m in freshwater zones.Deep groundwater consists of unconfined freshwater,with its dynamics primarily driven by pumping activities,exhibiting a maximum fluctuation of 27.58 m.Both aquifers displayed remarkable seasonal co-variation and highly synchronized patterns:groundwater levels remained relatively high under natural conditions during January-February,progressively declined to their lowest levels due to intensive pumping from March to June,recovered during July-September with rainfall recharge and reduced extraction,and stabilized from October to December.④ Analysis of Gaussian model parameters through the nugget-to-sill ratio revealed moderate spatial correlation for both deep and shallow groundwater depths in January,February,and December,with strong spatial correlation observed during the remaining months.Deep groundwater consistently exhibited stronger spatial correlation than shallow groundwater.These spatial correlation patterns showed strong association with groundwater extraction processes,where intensified pumping correlated with enhanced spatial correlation,and vice versa.