[A-HW18] Material transportation and cycling at the land-sea interface: from headwaters to the ocean

[AHW18-19] Modelling suspended sediment transport in a large forested catchment of Western Japan using Soil and Water Assessment Tool

*Nang Yu War¹, Shin-ichi Onodera¹, Kunyang Wang¹, Yuta Shimizu², Mitsuyo Saito¹ (1.Graduate School of Advanced Science and Engineering, Hiroshima University, 2.Western Region Agricultural Research Center, National Agriculture and Food Research Organization)

Keywords:SWAT, streamflow, suspended sediment, modelling

In 2018, long-time precipitation over 48 hours in western Japan caused serious flooding along the Takahashi river, resulting in the damage of river banks, and loss of lives. The massive load of suspended sediments moves along with the high flow during the flooding, resulting in the accumulation of huge amount of sediments near the estuary area after the flooding. This event spotlights the requirement of the estimation of suspended sediment movement during flood for disaster prevention and preparedness. Takahashi is a large forested catchment with three main tributaries: Takahashi, Nariwa and Oda, each possessing its own characteristics. Moreover, the geology of the Takahashi catchment is complex since it is partially karstic watershed. This study aims to model the streamflow and suspended sediment transport in Takahashi river using the Soil and Water Assessment Tool (SWAT) and to test the effectiveness of SWAT modelling in the partially karstic characteristics catchment. The daily flow and suspended sediment data from three hydrological station (2002 – 2007) were used for calibration and validation of the model. The statistical indexes Nash-Sutcliffe Efficiency (NSE) value for calibration ranging from 0.66 - 0.74 and, validation ranging 0.55 – 0.7 with PBIAS values within ±15, indicating that the simulated model is satisfactory.

This research is supported by APN Project (CRRP2019-09MY-Onodera).