Study on numerical simulation of morphodynamic processes of braided rivers

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Jian Sun, BINLIANG LIN

Tuesday 30 june 2015

14:20 - 14:35h at Oceania (level 0)

Themes: (T) Sediment management and morphodynamics, (ST) River morphodynamics

Parallel session: 6B. Sediment - River

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As one dynamic element in the earth surface, rivers have been concerned by geologists, geo-morphologists, sedimentologists, hydraulic engineers and so on. Although many efforts have been made by scientists in relative disciplines, the mechanism of river evolution is not fully known due to the complexity. The braided river is one of such river patterns with complex planform appearances and dynamic evolution properties, which contains a network of multi-thread streams that split off and re-join each other. The dynamical elements of braided rivers, such as the bars, bifurcations and confluences, have been investigated and measured both in fields and in laboratories. In recent years, both the cellular models with reduced-complexity method and physical-based models have been attempted to simulate the dynamic processes of braided channel patterns. In most of these numerical simulations, disturbances were widely introduced into the initial or boundary conditions: the perturbation of white noise in the initial bed elevation or the disturbance of an initial bar at the inlet. Although there are disturbances existing in real world, such as uneven sandy bed and the uncertain arrangement of sands, most of the disturbance are used as an artificial approach to induce the braiding pattern. However, the effect of disturbance in the development of braided pattern have not been clear so far. In this study, a physical-based model is established to simulate the braided channels. It is found that the disturbance is not a necessary prerequisite in the generation of braiding pattern. The impacts of the disturbance on the channel development are further investigated.