Developing Mathematical Models of Saturated Hydraulic Conductivity in Iraqi soils

Saturated hydraulic conductivity (Ksat) is a fundamental parameter in hydrology and modeling surface and groundwater flow, as well as the transport of dissolved materials within the soil. Estimating saturated conductivity by field or laboratory methods is often expensive and time-consuming. The hydraulic conductivity parameter is the most important parameter in modeling the hydraulic properties of soils in saturated and unsaturated soils and is subject to high variability and spatial differences across spatial scales. The study aims to develop a mathematical model for estimating the saturated hydraulic conductivity (ks) in Iraqi soils using basic physical properties. A theoretical model was initially proposed based on effective relative porosity ( er). However, regression analysis performed on empirical data collected from multiple soil samples across Iraq indicated that proposed theoretical relationship (ks = 75. er) did not hold under actual conditions. Instead, an empirical model was derived using linear regression Ks= 12.29 er+ 24.5, with a coefficient of determination (R2) of 0.443. This model suggests a moderate inverse correlation between er and ks, likely due to textural and structural characteristics specific to the studied soils. The findings emphasize the need for localized calibration of hydraulic models to ensure accuracy in soil-water management practices.