黄河三角洲浅表层渗透系数时空格局及对变化环境的响应OA

To investigate the spatiotemporal distribution characteristics of the shallow subsurface hydraulic conductivity(K)and its response to changes in the sedimentary environment,the Yellow River Delta was selected as the study area.In July 2024,a total of 96 soil samples were collected from the surface and depths of 10 cm,30 cm,and 50 cm below ground level in the Yellow River Delta.Particle size analysis was conducted,and empirical formulas were applied to calculate the average hydraulic conductivity at each depth as well as the equivalent shallow subsurface hydraulic conductivity.The calculated results were validated through in-situ standpipe tests.The study found that the shal-low subsurface sediments in the delta primarily consist of clay and sand.The mean particle sizes at the surface,10 cm,30 cm,and 50 cm depths were 28.8 μm,26.1 μm,29.9 μm,and 29.1 μm,respectively.Compared with sampling results from 2015,the standard deviations of particle sizes d10,d50,and d90 decreased by 26.2％,47.8％,and 30.4％,respectively.The K values ranged from 0.02-3.10 m/d in 2015 to 0.10-1.54 m/d in the current study,indicating improved sediment sorting.Although the mean K value showed little change,spatial varia-bility decreased significantly.In the Diaokou River protected area,the spatial variability of K was relatively low.In the general protected zones of the Yellow River Delta wetlands,K values were generally higher than those in the core protected areas.The horizontal equivalent hy-draulic conductivity of shallow subsurface sediments in the protected areas ranged from 0.07 to 1.78 m/d,while the vertical equivalent hy-draulic conductivity ranged from 0.03 to 1.51 m/d.The ratio of horizontal to vertical K was 1.18,indicating significant isotropy.These chan-ges reflect the comprehensive influence of factors since 2015,including variations in water and sediment discharge from the Yellow River,wetland water replenishment operations,and conservation measures.