Water-salt transport characteristics of saline soil under hydraulic remediation measures in the Yellow River Delta region of China

To understand the water-salt transport process of saline soils in the Yellow River Delta region under traditional hydraulic remediation measures and to determine its engineering parameters, this study made laboratory investigations to measure the soil salt content using three remediation practices under simulated rainfall conditions. The results indicated that under the rainfall intensity of 100 mm/h, 6-8 h are needed for the soil salt content to tend to be constant. The distribution of the salt content presents a typically symmetrical shape regardless of the position of the saline soil relative to the concealed pipe, the open ditch, or the vertical shaft. The two-parameter exponential function indicates the relationship between the soil desalination rate and the horizontal distance from the pipe, ditch, or shaft. The maximum spacings to build the salt drainage engineering projects of the concealed pipe, open ditch, or vertical shaft in the laboratory are 4.79 m, 2.88 m, and 2.19 m, respectively. The effectiveness of salt drainage for coastal saline soils can be ranked from highest to lowest as first the concealed pipe, then the open ditch, and finally the vertical shaft. The findings provide an experimental basis and reference for the application of hydraulic measures to remediate saline soils in this region.