丘陵地斜面における macropores と雨水浸透

The presence of large continuous openings (macropores) close to the surface of the soil isvery important in the process of infiltration of rainfall. The influence of macropores on infiltra-tion is discussed on the basis of both field infiltration tests and theoretical studies.The results of infiltration tests using artificial rainfall equipment and of soil surveys in theslope of Tanida research basin, disclosed that the final infiltration rate is too large for theprevailing soil character and that a large number of cracks and holes has been formed in thesoil layer by the shrinking of the clay layer and rotting of roots.Based on these observations, a simulation model for predicting infiltration into soil withmacropores is developed. In this model, the flow in macropores and the clay soil is calculatedusing Richards equation and iterative Galerkin-type finite element method. The calculated re-sults agree well with the infiltration curves obtained from field tests.