[A-HW20] Hydrology & Water Environment

[AHW20-04] Investigating the validity of a meso scale constitutive equation using micro scale water dynamics simulations for hillslope rainfall-runoff processes

*Yutaka Ichikawa¹, Yuusuke Mori¹, Yasuto Tachikawa¹ (1.Graduate School of Engineering, Kyoto University)

Keywords:rainfall-runoff, hillslope, depth-discharge relationship, constitutive equation

A number of rainfall-runoff models have been developed in the field of hydraulic and hydrologic engineering, with a special attention on simulating temporal patterns of river discharge in order to meet practical demands such as discharge predictions. Conceptual rainfall-runoff models were initially developed, followed by physical-based models. The physical-based models have achieved a certain level of success, which was partly due to the considerable advancement of computers and the increasing availability of a variety of datasets. It is pointed out, however, that recent important findings based on field studies are not incorporated into rainfall-runoff models, especially used for engineering purposes. To examine the raised issue, this study conducted detailed simulations coupling surface flow and saturated-unsaturated flow for hillslope rainfall-runoff dynamics, and investigated the validity of a constitutive equation used in a rainfall-runoff model. The results revealed that the constitutive equation was capable of describing depth-discharge relationships for hillslopes with relatively shallow soil layers but not for those with thick soil layers.