The impacts of the tide on the hydraulic geometry and flow division in the distributaries channel.

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Thursday 2 july 2015

17:33 - 17:36h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Morphodynamics of estuaries and coastal areas, Poster pitches

Parallel session: Poster pitches: 13A. Sediment - Coast

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Hydraulic geometry is the relations between the channel's width, depth, flow velocity, as well as the flow fluxes. However, in a tidally influenced river deltas, the hydrodynamics are determined by the interaction of the upstream discharge and the downstream tidal flow. Therefore, the channel geometry is developed with not only the river discharge but also the tidal prism. In this paper, the maximum tidal discharge amplitude is used to represent the relationship with the channel geometry in the Pearl River Delta (PRD). Splitting the tidal prim and river discharge, the relationship between the channel geometry and discharge can present different trend and transition from the delta apex to the downstream, respectively. Meanwhile, the river discharge, tidal prism, velocity and depth decrease along the distance, because of the increase of the number of the distributary channel. The ratio of the tidal prism and river discharge is increasing, which indicate that the influence of the tide in the downstream is more serious than it was in the upstream. Based on the numerical model, a 2-D model is used to simulate the hydrodynamic process in the different period morphology of the PRD. The result indicates that the tide in Pearl River networks generally counteract the asymmetry of flow division.