To address the difficulty of explaining the causes of patchy salinization in the Hetao Irrigation District using traditional two-dimensional frameworks, this study aims to examine whether the interaction between shallow clay layers and the groundwater table is associated with the spatial differentiation of salinization. Employing a multi-scale investigation approach based on sampling data from 114 shallow boreholes and 3 typical deep boreholes, and combined with principal component analysis, this research evaluates the role of matrix configuration in water and salt redistribution. The spatial relationship between the burial depth of the shallow clay layer and the groundwater table may play an important role in regulating vertical water–salt redistribution and influencing salt retention, thereby representing a potential structural mechanism contributing to patchy salinization. When the clay layer is located within the groundwater fluctuation zone, a positive feedback process is potentially associated with severe salt patches (surface mean of 6.17 g/kg); When the clay layer is situated above the phreatic water level, bidirectional retardation occurs, leading to moderate salt accumulation (mean of 2.71 g/kg); under the deep salt storage pattern, the surface shows relatively low salinity (mean of 1.61 g/kg), but a possible deep salt accumulation zone may occur at depth. This study extends traditional two-dimensional evaluation frameworks by proposing that the three-dimensional reshaping of water and salt evolution pathways by the dynamic interaction between the clay layer and the groundwater table may represent a potential structural mechanism contributing to patchy salinization formation. These findings provide a useful scientific basis for salinization diagnosis and potential zonal management in the irrigation district.
Tai et al. (2026) studied this question.