Hierarchical Analysis of Vertical and Horizontal Variability in Alluvial Soil Properties within the Wadi Souf Al-Jin Plain between Southern Tawergha and Qararat Al-Qataf, Libya

Abstract

This study aimed to analyze the hierarchical structure of vertical and horizontal variability in alluvial soil properties within the Wadi Souf Al-Jin floodplain, located between southern Tawergha and Qararat Al-Qataf, Libya, using linear mixed-effects modeling. The analysis was based on 162 soil prnjofiles comprising 505 genetic horizons. The investigated properties included soil pH, electrical conductivity (EC), calcium carbonate (CaCO₃), and particle size fractions. Descriptive statistics revealed that EC exhibited the highest coefficient of variation (156.93%) with strong positive skewness, whereas pH showed minimal relative variability (3.87%). Mixed-effects modeling indicated strong horizontal dominance for EC (ICC = 0.672), with 67.2% of total variance attributed to between-profile differences, while CaCO₃ showed vertical dominance (ICC = 0.139). Marginal and conditional R² values highlighted the importance of incorporating spatial hierarchy in explaining soil variability, particularly for salinity-related properties. The findings demonstrate a multi-scale hierarchical variability pattern consistent with depositional heterogeneity in arid floodplain environments and emphasize the need for spatially differentiated land management strategies in arid agricultural planning