A Study for Application of Vertical Infiltration in Runoff Analysis Model to Long- and Short- Term Evaluation

In general, the runoff phenomenon at the time of a flood is consisted of a series of runoff components. For example, Horton (1933) proposed that when the rainfall amount is over then the limit capacity of soil permeation, the other water would be output as the surface runoff. Kikkawa et. al (1979) considered that sub-system of the discharge decreasing progressively for the tank model. And Kure et. al (2005) recommended the smallest scale tank for unique slope including of the characteristics of soil, topography to calculate the rainfall- runoff volume. However, the physical meaning of these researches was not very clearly. Therefore, the authors would focus on it and develop the multi-layers flow as the main model to evaluate the flood runoff in a short term and long term period.

First the historically rainfall-runoff model considering multi-layer flow in a slope is proposed. The purpose of this study is to propose the runoff model in consideration of multi-layer flow and to indicate possible application of long-and short-term runoff analysis. It shows outline of proposed rainfall-runoff model considering multi-layer flow in a slope. Additionally, it argues over the difference of reproducibility from existing model. And finally, this model is applied to long-and short-term runoff analysis at a small dam basin (254km²) in Japan. In conclusion, the model considering multi-layer flow was able to be proposed by incorporating no difficulty involved vertical infiltration mechanism to the existing model. As a result of runoff analysis at the dam basin, the availability of the proposed model is shown.