[A-CG42] Water and sediment dynamics from land to coastal zones

[ACG42-01] The fate of riverine freshwater in the ocean

*Shinichiro Kida¹, Ryo Abe², Yosuke Alexandre Yamashiki³ (1.Research Institute for Applied Mechanics, Kyushu University, 2.Interdisciplinary Graduate School of Engineering Sciences, 3.Graduate School of Advanced Integrated Studies in Human Survivability)

Keywords:river plume

Riverine freshwater is a buoyancy source for the ocean and spreads the coast as it mixes with oceanic water and establishes a river plume at the sea surface. Continental-scale rivers tend to create river plumes that are trapped along the coast and continue for a long distance. Regional-scale rivers, on the other hand, tend to create river plumes that mix close to the river mouth and are more short-lived. We investigated the fate of riverine freshwater after a heavy rain event for regional-scale rivers using a river-ocean seamless model. Model results show the formation of gravity-current like river plumes and that the roles of small-scale rivers are non-negligible for establishing the salinity distribution near the coast. We will also introduce recent high-resolution observations using drones which is becoming a convenient method to capture the behavior of river plumes.