Simulating infiltration into stony soils with a dual‐porosity model

Soils containing rock fragments are widely distributed in the world. However, literature on the dynamic simulation of water movement in stony soils is scarce. In this paper, a dual‐porosity model was used to simulate water infiltration into soils containing rock fragments. Sensitivity analysis of the dual‐porosity model parameters demonstrates that the increase of rock fragment content clearly decreased infiltration into stony soils. Big stones hampered infiltration more than small stones. Spherical stones accelerated infiltration compared with solid, cylindrical stones and rectangular, slab‐like stones. Numerical analysis was also performed to test and compare a non‐equilibrium dual‐porosity model (NDPM) with an equilibrium dual‐porosity model (EDPM) and an equilibrium single‐pore model (ESPM). Infiltration experiments on disturbed soils were carried out to verify the ability of the NDPM to simulate infiltration into stony soils. Based on hydraulic parameters of soils without rock fragments and mass transfer coefficients obtained independently, the extrapolated cumulative infiltrations calculated by the NDPM were in good agreement with the observed data. Fitted model parameters of the NDPM indicate that rock fragments not only act as a source or sink to affect infiltration but also change the pore structure of the fine earth, apart from reducing the cross‐sectional area for water flow. Though further studies are required to improve the dual‐porosity model, it already describes more characteristics of infiltration into stony soils and explains more phenomena than does the single‐porosity model.