Yuichi INO

Infiltration Analysis for Unsaturated Soils and Distributed Runoff Model

Norio HAYAKAWA

In development of the distributed runoff model, a reservoir-type model like the Xinanjiang model which generates the surface outflow and the infiltration flow out of the rainfall is incorporated in the distributed way. In this kind of the reservoir model, the inputted rainfall is first stored in the fictitious reservoir first and the excess surpassing the reservoir capacity is discharged as the runoff. There remains a doubt in this kind of the reservoir model whether the parameters involved in the model actually correspond to the movement of infiltrated water within the soil layer. In this study, therefore, the infiltration process of rain water to the unsaturated soil layer is analyzed numerically by solving the partial differential equation of infiltration flow. The calculation result is then used to estimate the parameters in the Xinanjiang model.