[A-HW22] Material transportation and cycling at the land-sea interface: from headwaters to the ocean

[AHW22-P05] Evaluating sediment transport influences and management in steep sediment disaster vulnerable catchment

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

Keywords:steep slope, sediment, SWAT, disaster management, curve number

Rainfall-induced floods and suspended sediments impact water quality and human well-being. Steep slope catchments with rapid flow in Japan are susceptible to flood and sediment disasters under torrential rainfall despite forests being the dominant land use type. Precipitation intensity increased with the changing climate, resulting in increased sediment loading in Japanese rivers. This study used the Soil and Water Assessment Tool (SWAT) on a steep catchment to identify factors influencing high sediment yield and evaluate the effectiveness of the sediment filter strips in reducing sediment disaster risk. The calibrated and validated model simulated the streamflow and sediment transport of the studied catchment satisfactorily and highlighted the areas requiring the prevention of high sediment yield. We found that the slope is the most influencing factor for high sediment yield, followed by the daily average curve number. The filter strips for controlling the high sediment contribution to the river from steep-high-sediment-yield areas showed that strip with 5-m width was the most efficient for sediment retention, reducing the catchment sediment output by 14%.

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