Hydropedogenic dynamics of arid urban soils under episodic soil waterlogging in Oman

Abstract In the hyperarid Arabian Gulf, climate change and urbanization intensify hydropedogenesis; in Muscat, rising shallow moisture waterlogs urban depressions, producing episodic, near-saturated topsoils. These shifts reflect profound disturbances in the soil–water–atmosphere continuum. This study aims to (i) characterize the morphological, physico-chemical, and mineralogical properties of urban arid soils subjected to nearly five decades of waterlogging, and (ii) examine hydropedological signatures and pedogenic evolution driven by fluctuating moisture regimes in an alluvial urban wadi. A multi-faceted approach was employed, including morphological and micromorphological analyses, XRD-SEM, and petrography, alongside geophysical surveys and hydrogeochemical profiling. Pedons were excavated across the wadi and sampled for texture, pore-water EC and pH, and mineralogy. Rapid pedogenesis in the studied arid vadose zone is driven by seasonal wetting–evaporation cycles, shallow fluctuating moisture levels (few cm to 3 m), and elevated salinity (TDS 8–22 g/L). Hardpans of caliche and gypsum, formed by upward evaporative fluxes, impede percolation and intensify salt accumulation near the surface. XRD–SEM and micromorphology confirmed salt features and palygorskite formation driven by salinity and carbonate enrichment. Surface expressions include blistered microrelief and friable, heaved patches. Geophysics mapped moisture-retention zones; groundwater chemistry indicated mineral dissolution and episodic saturation. Chronic waterlogging from altered hydrology accelerates soil transformation in arid urban areas. The study underscores the importance of incorporating shallow soil saturation dynamics into urban water management and land-use planning. Under intensifying anthropogenic and climatic pressures, waterlogging renders urban arid soils early sentinels of environmental stress. This framework anticipates degradation trajectories and guides adaptive infrastructure.