Japan Geoscience Union Meeting 2025

Presentation information

[E] Poster

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG37] Water and Sediment Dynamics from Land to Oceans [En]

Tue. May 27, 2025 5:15 PM - 7:15 PM Poster Hall (Exhibition Hall 7&8, Makuhari Messe)

convener:Dhruv Sehgal(Project Researcher, University of Tokyo), Dai Yamazaki(Institute of Industrial Sciences, The University of Tokyo), Janaka Bamunawala(Tohoku University), Moein Farahnak(Ecohydrology Research Institute of University of Tokyo)

5:15 PM - 7:15 PM

[ACG37-P07] Quantifying sediment outflow and related uncertainties from rivers in Japan to the ocean

*Dhruv Sehgal1, Dai Yamazaki1 (1.Institute of industrial Science, The University of Tokyo)

Keywords:Sediment flux, Global sediment transpot model, Suspended sediment, Extreme events

Sustenance of the marine life cycle is important for long term sustainability of the planet. Marine life feeds on the sediment and nutrient outflow from rivers to the oceans. Rivers serve as vital conduits, transporting sediment and nutrients from terrestrial landscapes to coastal oceans. In global-scale river studies, this process plays a significant role in shaping the hydrodynamics and ecosystems of coastal regions. However, the interactions between river discharge, sediment transport, nutrient flux, and their impacts on coastal oceans remain insufficiently understood. Furthermore, climate change leading to high discharge events and anthropogenic changes affect the accurate quantification of sediment fluxes. This research aims to address this knowledge gap by investigating the dynamics of sediment outflow from rivers in Japan and its broader implications for coastal ocean systems in the world.

The primary objective is to estimate the sediment outflow from terrestrial areas during periods of heavy discharge. Utilizing advanced numerical modeling techniques, such as the CaMa-Flood model, we aim to quantify the magnitude and spatial distribution of sediment transport from rivers to coastal oceans. By integrating data on river discharge, soil erosion, land use patterns, and precipitation, we seek to develop a comprehensive understanding of the dynamics driving sediment fluxes across Japan. However, reasonable parameterization of global sediment transport equations is required to determine an appropriate time step for sediment transport estimation. Catchment characteristics define the appropriate sediment time step used in physical sediment transport models. Fluctuations in sediment yield/flux from rivers to the oceans can result from variations in the sediment time step used in modeling sediment transport.

In summary, we seek to address the following research questions: How do large-scale runoff events from terrestrial areas impact the hydrodynamics and ecosystems of coastal oceans through the supply of freshwater, sediment, and nutrient elements? How does the selection of an appropriate modelling timestep reduce uncertainty in sediment flux predictions? Thus, this research aims to advance our scientific knowledge on riverine and coastal sediment management strategies.