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

[AHW22-08] High temporal resolution SWAT modeling for assessing extreme hydrological events and sediment transport in steep catchments

*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:sub-daily, SWAT, flood events, extreme climate, steep catchment

The steep slopes of Japanese river catchments are vulnerable to floods and sediment disasters. This study presents an advanced application of the Soil and Water Assessment Tool (SWAT) to model high-flow events in steep catchments on an hourly scale. SWAT is widely used for simulating both long-term continuous and short-term event-based processes. Focusing on the Takahashi River in Japan, known for its steep topography and heavy rainfall, the research evaluates the SWAT model's capability to simulate extreme flood events in hourly time steps, simulate flood events and sediment transport with a lack of observed data, and analyze the model's performance with the antecedent conditions of the pre-events. Among the flood events from 2002 to 2007, events with a daily average streamflow greater than 500 m^3/s are selected for calibration and validation. We found that the SWAT model can very well simulate the hourly extreme flood events. It is observed that the model's performance on both streamflow and sediment is more satisfactory if the events have moist antecedent conditions with low total precipitation during the event. This work contributes to the understanding of the complex hydrological processes in steep catchments and offers insights for effective flood and sediment management in similar environments, highlighting the importance of high-resolution modeling in predicting and mitigating disaster risks.

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