Effective hydraulic properties of 3D virtual stony soils identified by inverse modeling

Abstract. Stony soils that have a considerable amount of rock fragments (RFs) are widespread around the world. However, experiments to determine effective soil hydraulic properties (SHPs) stony soils, i.e., water retention curve (WRC) and conductivity (HCC), challenging. Installation measurement devices sensors in these is difficult, data less reliable because their high local heterogeneity. Therefore, especially under unsaturated conditions still not well understood. An alternative approach evaluate SHPs systems with internal structural heterogeneity numerical simulation. We used Hydrus 2D/3D software create virtual 3D simulate flow for different volumetric fractions RFs, f. values f from 11 % 37 were created by placing impermeable spheres as RFs sandy loam soil. Time series pressure heads at various depths, mean contents, fluxes across upper boundary generated evaporation experiment. Additionally, multistep unit-gradient simulation was applied near saturation up pF=2. The evaluated inverse modeling, assuming homogeneous system, identified. compared predictions available scaling models Our results showed WRC background based on only value gives acceptable case RFs. reduction could be simply scaled Predictions highly improved applying Novák, Maxwell, GEM scale HCC. Maxwell model matched numerically identified HCC best.