Riparian or aquatic vegetation thrives with seasons. The understanding of canopies' Submergence‐Ratio (SR = stem height/water depth) influence on suspended sediment transport is still limited. Thus, Large Eddy Simulations coupled with the Discrete Phase Method are used to investigate the particles' three‐dimensional distribution in a partially vegetated straight channel. The spanwise distribution of particles are quantified by the probability density function (PDF), showing a non‐uniformity of particles in time as quantified by the PDF variance. We found that (a) with SR rising, the particles' depletion effects exerted by the vegetation‐side mixing layer is improved along the interface between vegetated and vegetation‐side bare channel region. However, the SR has little effect on the variance of the particles' PDF in the spanwise direction when the mixing layer is fully developed. (b) During the developing stage of the over‐canopy mixing layer, submerged vegetation with higher SR gains a stronger upwards (vertical) entrainment capability. The case (SR = 60%) has a higher sediment concentration than other cases in the fully developed vertical mixing layer region over canopy. (c) The vertical suspension of particles in the vegetation‐side bare channel region is analyzed. Particles migrating from the vegetated region are entrained into the vegetation‐side bare channel region by turbulent structures. Nevertheless, the vertical concentration profile is more uniform in the vegetated region than in the vegetation‐side bare channel at the same streamwise location. The cases SR = 40% and 60% still have higher sediment concentration than other cases in the vegetation‐side bare channel's upper region.

Rectangular short-crested weirs are widely used for simple structure and high discharge capacity. As one of the most important and influential factors of discharge capacity, side slope can improve the hydraulic characteristics of weirs at special conditions. In order to systemically study the effects of upstream and downstream slope coefficients S₁ and S₂ on overflow discharge coefficient in a rectangular short-crested weir the Volume of Fluid (VOF) method and the Renormalization Group (RNG) κ-ε turbulence model are used. In this study, the slope coefficient ranges from V to 3H:1V and each model corresponds to five total energy heads of H₀ ranging from 8.0 to 24.0 cm. Comparisons of discharge coefficients and free surface profiles between simulated and laboratory results display a good agreement. The simulated results show that the difference of discharge coefficients will decrease with upstream slopes and increase with downstream slopes as H₀ increases. For a given H₀, the discharge coefficient has a convex parabolic relation with S₁ and a piecewise linearity relation with S₂. The maximum discharge coefficient is always obtained at S₂ = 0.8. There exists a difference between upstream and downstream slope coefficients in the influence range of free surface curvatures. Furthermore, a proposed discharge coefficient equation by nonlinear regression is a function of upstream and downstream slope coefficients.

Combined orifice-weir flow is a complex phenomenon in hydropower and the discharge capacity of a structure affects the safety of the structure. It is essential to propose an equation for computing the discharge coefficient of combined orifice-weir flow. Based on theoretical analyses and physical experiments, 284 laboratory tests were performed to determine the discharge coefficient. The parameters affecting the discharge coefficient were determined and the relationships between the coefficient and four parameters, that is, the ratio of the water head to the upstream water level, the ratio of orifice height to orifice-weir height, the ratio of orifice height to the water head, and the ratio of the length to the height of the orifice-weir structure, were established. According to the dimensional analysis and the linear-fitting method of multidimensional ordinary least squares, five models were constructed to analyze the sensitivity of the model’s accuracy by using different parameters. The sensitivity to each parameter was also evaluated. The results were examined with statistical indices and they showed that one model yielded the best results, which were consistent with the experimental values. Thus, the proposed model is effective in estimating the discharge coefficient of combined orifice-weir flow.

The implementation of floating structures has increased with the construction of new sluices for flood control, and the hydrodynamic moment of a floating structure affects the safety and operation of that structure. Based on basic hydrodynamic theory, theoretical analysis and 121 physical model tests were conducted to study the relationships between the hydrodynamic moment and the influencing factors of floating structures, namely, the shape parameter, hydraulic conditions, and draft depth. Stepwise regression fitting based on the least squares method was performed to obtain a mathematical expression of the hydrodynamic moment, and the experimental results show that hydrodynamic factors significantly influence the hydrodynamic moment of such structures. The results predicted by the mathematical expression agree with the experimental results, and thus, the proposed expression can be used to comprehensively analyze and study the safety of a floating structure under the action of flow in finite water.