3D Image‐Based Pore‐Network Simulations to Analyse Soil Pore Architecture Variations due to Wetting and Drying Cycles

Soils are frequently exposed to wetting–drying (W‐D) cycles, which strongly influence pore structure and flow properties. Although prior studies have investigated their effects on absolute permeability ( k ) and capillary pressure, the impact on relative permeability remains poorly understood. Here, we used high‐resolution X‐ray microtomography and pore‐network modelling to investigate how repeated W‐D cycles (zero and six cycles) alter pore architecture and flow properties of an Oxisol under four management systems (minimum tillage, conventional tillage, no‐tillage and forest). We quantified k , capillary pressure curves, wetting‐ and nonwetting‐phase relative permeabilities, as well as pore‐scale descriptors. Our results showed that W‐D cycles generally increased k and pore connectivity but caused little change in specific surface area. Shifts in capillary pressure curves highlighted the role of larger pores, particularly at higher water contents. To better evaluate flow behaviour, we applied the total relative permeability deficit concept, which integrates wetting‐ and nonwetting‐phase relative permeabilities over drainage and imbibition processes. The total relative permeability deficit proved more sensitive than relative permeability alone in distinguishing management effects: it remained similar for minimum tillage and forest soils but differed significantly for conventional and no‐tillage systems. These findings demonstrate that the total relative permeability deficit is a robust metric for capturing management impacts on soil hydraulic behaviour and provides new insights into how W‐D cycles affect flow processes in structured soils.