Parameterization of a Distributed Rainfall-Runoff Model in Japan Based on Soil Particle Distribution Information

Abstract

Regionalization of hydrological models is considered as a potential solution to address Discharge Predictions in Ungauged Basins (PUB). Differing from conventional regionalization, a few studies have considered within-catchment heterogeneity and integrated it into grid-based distributed hydrological models. This approach aims to assign a corresponding parameter set to each grid cell accordingly to enhance the parameter transferability. Our previous study performed the grid-based regionalization of a distributed hydrological model 1K-DHM over Japan, with applying an identified model parameter sets (IP) for seven geospatial type. However, it is believed that particle information of the soil is more related to hydrologic processes in rainfall-runoff phenomena. In this study, we reclassified spatial soil distribution information according to particle size information and hence, added three more geospatial types, which were named as “fine-grain soil”, “coarse-grain soil” and “gravel-grain soil”. Compared to the previous one, our intention is to explore a more stable regionalization considering soil particle information.