[A-OS10] Continental Oceanic Mutual Interaction - Planetary Scale Material Circulationn

[AOS10-02] River-ocean interaction across a mega-delta

*Shinichiro Kida¹, Dai Yamazaki² (1.Research Institute for Applied Mechanics, Kyushu University, 2.Institute of Industrial Sciences, The University of Tokyo)

Keywords:River-ocean interaction, Delta

The Ganges-Brahmaputra river is a major source of freshwater for the Bay of Bengal. River discharge occurs through the Ganges-Brahmaputra Delta, which consists of multiple river mouths. The seasonal cycle of this river discharge is observed with a minimum from late winter to early spring and a maximum from late summer to early fall. We investigated how the dynamics of this river discharge occurs near the river mouth based on a high-resolution numerical model that resolves the various channels of the Ganges-Brahmaputra Delta. The model simulates the basic seasonal cycle of the river discharge that is comparable to observations, with a river plume forming from the major river mouth and along the coast. We find that the river outflow through the main channel influences the surrounding narrow channels through the formation of this river plume by raising the sea level at the river mouth and reversing the direction of the flow. While the widths of these narrow rivers are narrow and less than the deformation radius, our model results suggest active river-ocean interaction occurring across the delta.