Implementing Anisotropy Ratio to Modeling of Water Flow in Layered Soil

Abstract

Anisotropy of saturated hydraulic conductivity (Ks, m s‐1) is a major input datum required for the modeling of saturated and unsaturated water flow in soils, significantly improving the reliability of the models. But, there are several known literature reports presenting positively verified examples of modeling of infiltration in horizontally layered small‐scale soil profiles without taking anisotropy into consideration. The objective of this paper is to analyze the influence of implementing the anisotropy ratio to the two‐dimensional mathematical model of unsaturated flow in a selected small‐scale multilayered soil profile on the possible improvement of calculations results. Two methods of soil sampling for anisotropy measurement were considered—small cylinder and cubic sampling. Our numerical model reflected the profile of a single bench terrace equipped additionally with draining sand ditch, located in Olszanka, Poland. The simple regression analysis indicated that implementing the ratio of anisotropy of saturated hydraulic conductivity to the mathematical model of variably saturated water flow in the studied horizontally layered soil profiles did not result in more precise effects of time‐variable soil moisture calculations (R2 = 0.773–0.883, P = 0.05). Moreover, results of the statistical calculations for volumetric water content and vertical flow velocity, assuming isotropic and anisotropic medium with anisotropy coefficient obtained on the basis of cylindrical and cubic samples, appeared to be comparable; the notable differences were observed only in the case of calculated horizontal flow velocity.