Author(s): Professor Ben Chie Yen; Professor Ali Osman Akan

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Abstract: Soil properties have profound effects on overland flows over porous media. These effects are investigated by using a surface-subsurface flow conjunctive simulation model which solves the Saint- Venant equations for the overland flow and Richards' equation for the two-dimensional unsaturated and saturated porous medium flow. Guided by a dimensional analysis, four soil properties are studied, namely, porosity, vertical and horizontal saturated hydraulic conductivities, and unsaturated soil hydraulic characteristics which is expressed in two pairs of parameters describing the relationships between the degree of saturation and suction pressure, and between the relative conductivity and suction pressure, respectively. The results confirm the common belief that overland flow increases for decreasing soil porosity or saturated conductivity while the infiltration into the soil decreases. The effect of the ratio between horizontal and vertical saturated conductivity is insignificant, indicating the soil anisotropic effect is unimportant. Moreover, the overland flow decreases and infiltration increases for soils having small suction pressure head in the saturation and relative conductivity vs. suction pressure relationships, corresponding to, e.g., increasing soil particle sizes, than for soils having large suction pressure head.

DOI: https://doi.org/10.1080/00221688309499442

Year: 1983