ENVIRONMENTAL MODELLING OF SOIL WATER CHARACTERISTIC CURVE FOR TWO CONTRASTING SOIL TEXTURE

Abstract: Recently, due to the growing concern about the quality of the environment for unsaturated subsoil, which is negatively affected by agricultural and industrial activities, it becomes necessary to increase knowledge about the mechanism of transmission and distribution of solute and pollutants in the soil environment by modeling their movement in the soil under different conditions. Predicting soil water characteristic curve from van Genuchten model was renowned for reducing the costs and time of measurement methods. The aim of this study was to determine the effect of two levels of compaction on the behavior of soil water characteristic curve of a sandy loam and clay soils, and then compare the measured results with the predicted results obtained from van Genuchten equation with using four different model classes of (m) parameters, then investigating the relationship between them. At the end of the incubation period, soil samples were sampled and thereafter compacted through soil core with known volume at soil bulk density (Pd) of 1.50 and 1.70 g cm-3 for a sandy loam soil and 1.20 and 1.35 g cm-3 for clay soil. The obtained results indicated that using van Genuchten equation to fitting water characteristic curve with variable (m) parameter had the highest correlation (R2), and lowest normalized root mean square error (NRMSE), as well as soil compaction significantly affected volumetric water content at the same observed section in both soil textures.