Numerical modelling of silt sedimentation and delta evolution
摘要
The dynamical theory of sedimentation is valuable for hydraulic engineering as well as for the understanding of evolution of the natural environment. An attempt is made at developing a two-dimensional dynamical model to study the sedimentation phenomena. The results show that sediment is first accumulated in the vicinity of coming flow, where the thickness of water column becomes smaller and the water velocity becomes larger during the sedimentation process; after the sediment is accumulated to some amount, the water velocity exceeds a critical value, and the enhanced turbulent process raises silt particles up from the bottom and transports them to the downstream and the lateral shallow areas, where deposition takes place; eventually a mature underwater delta is formed and extended gradually to the downstream region, and an isolated underwater island is also generated in the centre of the river. The slope of the delta formed in such a way is very sharp and frontwise.