Effects of topography on soil salinity distribution under freeze-thaw processes

Soil salinity distribution in cold regions is often affected by freeze-thaw processes, yet the influence of surface topography on salt transport dynamics remains poorly understood. Based on a validated numerical model, we investigate the effects of topography on salinity distribution under freeze-thaw conditions. Results show that freeze-thaw processes on a flat surface induce unstable convective fingering. In contrast, ridge-furrow topography promotes the development of stable salt plumes that preferentially form beneath surface depressions. Compared to the flat surface, ridge-furrow topography significantly accelerates downward salt transport following the thawing phase. Further quantitative analysis reveals that increasing ridge height promotes deeper vertical descent of high-salinity plumes and enhances the downward migration of the centroid of salt mass. These findings provide critical insights for understanding subsurface salinity dynamics and optimizing soil management in cold regions.