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The amount of fine sediment deposition in some river reaches in the permanent backwater zone of the Three Gorges Reservoir has exceeded predictions made during the design period of the reservoir. In this study, a series of laboratory experiments were conducted on field samples of fine sediment from the Zhongxian reach, a typical reach in the permanent backwater region of the Three Gorges Reservoir. Compared with the existing formulas, an improved incipient velocity function for fine-grained sediment deposits was developed that includes the influence of water pressure and molecular force. Here we present a 2-dimensional (2D), depth-averaged, hydrodynamic-morphological model for simulating channel evolution processes. The proposed velocity formula was considered in the calculation of sediment transport, and the improved 2D numerical model was applied to the sedimentation process of the Zhongxian reach. Comparisons between model simulation results and field measurements were in acceptable agreement, ...

A 1-dimensional (1-D) numerical model was developed to simulate the formation and distribution of fine sediment deposition in the Three Gorges Reservoir. Based on the research of fluid mud in estuaries, a dynamic submodel of gravity-driven, fine sediment transport was developed using the staggered grids and finite volume method and a 2-order Runge-Kutta time processing format. This submodel was first verified for fine sediment deposition in a typical section of Three Gorges Reservoir and was then combined with a 1-D hydrosediment transport submodel to reproduce sedimentation in the dam area of the Three Gorges Reservoir. Results for selected variables indicated that the distribution of sedimentation is in acceptable agreement with field observations and demonstrate the ability of the 1-D model to improve understanding of the fine sediment deposition in the Three Gorges Reservoir.

In this study, the modified preparation method of combining planetary and vibratory ball milling was proposed to prepare Mg based hydrogen storage alloy powders. The comparison of micromorphology and hydrogen storage behaviour between Mg2Ni prepared using the modified and conventional preparation methods were investigated experimentally. The comparison results showed that the combination of first planetary and then vibratory ball milling has more favourable effect on improving both the kinetics and the thermodynamics of ball milled Mg2Ni alloys. The sample synthesised by first planetary milling for 40 h and then vibratory milling for 30 h has faster hydrogen absorption kinetics and lower dehydriding onset temperature than those prepared by the single method of planetary or vibratory milling and hydriding combustion synthesis owing to its popcorn-like microstructure. Moreover, this kind of modified method reduces the reaction enthalpy and activation energy by up to ∼18 and 22% respectively.