Spatial and vertical variability of soil physico‐hydraulic properties and subsurface lithology in the Upper Indus Plain of Pakistan

Abstract Accurate characterization of soil physico‐hydraulic properties is critical for irrigation and drainage design, solute transport, soil–water–plant, and rainfall–runoff relationships. However, spatially representative datasets for these properties remain limited for the Indus Basin of Pakistan, where hydrological studies often rely on generalized parameters derived from other regions, introducing uncertainties in model‐based assessments. This study presents a basin‐scale integrated assessment of soil texture, bulk density, infiltration behavior, and soil moisture retention characteristics covering the Upper Indus Plain of Pakistan. Field‐based in situ measurements were conducted at 66 spatially distributed sites across four doabs (area between the two rivers) at surface, 0.5‐m, and 1.0‐m depths. An integrated methodological framework was employed, combining hydrometer analysis for soil texture, improved double‐ring infiltrometer tests for infiltration, pressure‐plate extractor for soil water retention, oven‐dried weight for bulk density, and resistivity survey for subsurface lithological assessment. Infiltration datasets were analyzed using the Horton and Philip cumulative infiltration models, while soil water retention behavior was quantified using hanging water column and pressure plate methods and parameterized using the van Genuchten model. Results indicate that the Horton infiltration model outperformed the Philip model for estimation of cumulative infiltration. Silty clay loam, sandy loam, and silt loam are the dominant texture classes. The soil with infiltration rates up to 30 mm/h remain predominant across the study area. This study provides robust and accurate baseline datasets along with an integrated methodological framework to support basin‐scale improved hydrological modeling, flood simulations, recharge estimation, and effective water resource management.