Abstract: [1] Concurrent measurements of bed load transport velocity (v) from the bottom tracking feature of an acoustic Doppler current profiler (aDcp) and bed load transport rate (gb) from conventional pressure difference samplers are presented. Data sets were collected from both gravel bed and sand bed reaches of the Fraser River, covering a bed material range of 0.25–25 mm. Strong relations, in which v explained >70% of the variability of measured gb, were observed in a gravel bed and a sand bed reach. Differences in correlation between v and gb among the contrasting environments are attributed to variations in both the bed load particle size and aDcp operating parameters. Similar values of v were associated with lower mass transport rates in a sand bed than in a gravel bed reach. A nondimensional data collapse, accounting for differences in bed load particle size, explained 42% of the observed variance of the combined data set. Longer averaging times were required in the gravel bed reach, likely due to the stochastic nature of bed load entrainment in gravels and the resulting heterogeneous bed load velocity field. Bed load transport was modeled using both shear stress models and a kinematic model that utilizes the estimated bed load velocity. The standard shear stress models provided poor matches to the measured bed load transport rates: the sand bed data were overpredicted, and the gravel bed predictions correlated poorly with the measured predictions. Use of the kinematic model yields an estimate for the product of bed load concentration and bed load layer depth. This work highlights the potential of acoustic techniques for estimating bed load.

Abstract: A proprietary one-dimensional numerical model was developed for predicting the amounts of sediment flushed and deposited in the reservoirs in series, the bed evolutions, and variations of the suspended solids concentrations along a river during the concerted sediment flushing events. The model consists of a flow movement module and sediment transport module in which the bed material load is taken as sediment mixture. The nonuniform property of the bed material load is modeled by the introduction of a mixing layer, transition layer, and deposition strata. The model was calibrated on the basis of the field data at Dashidaira and Unazuki reservoirs on the Kurobe River in Japan. The calculated results are in good agreement with the measurements. For the reservoirs out of Japan, the Ashida and Michiue bed load formula used in the model should be verified or replaced by other formulas.

Abstract: The environmental impacts of sediment flushing are predicted by a one-dimensional model for prediction and evaluation of sediment flushing (PESF1D). The model computes one-dimensional unsteady flow and non-equilibrium transport of non-uniform sediment mixtures. In the sediment transport module, bed material load is taken as sediment mixtures for calculating the bed evolution and wash load concentration is computed in consideration of the mixing action between the fine sediments in the flowing water and bed porewater. The influences of tributaries on the concentrations are taken into account in diffusion equations of wash load and suspended load. The non-uniform property of the bed material load is modeled by introduction of a mixing layer, transition layer and deposition strata. PESF1D was calibrated on the basis of the observations during the concerted flushing at Dashidaira and Unazuki reservoirs in 2001. The suspended solid concentrations predicted for potential flushing in 2002 are in good agreement w...

Abstract: Study of total sediment load transport is an important consideration of the fluvial process in many nowaday rivers. In order to improve the prediction of sediment transport and morphological behavior of the channel bed, a mathematical model taking bed load, suspended load and wash load into account has been developed. In contrast to previous researches, wash load has been especially accentuated from the perspective of cohesive sediment transport. For a better simulation of the interrelationship between different sediment loads and the river bed, cohesive and non-cohesive regimes were distinguished for the bed depending on the critical clay content. Two cases of with and without wash load have been performed using a 1D numerical modeling approach. The comparison between the computational results and field data exhibited its advantages over the conventional models.

Abstract: By the indoor flume model experiment, this paper studies the influence of vegetation dam on flow pattern and bed load sediment transportation of upper reaches end before the dam. The experiment was done under 1/150, 1/100 and 1/50 three base slopes with 5.09 L·s~(-1), 9.08 L·s~(-1) and 13.08 L·s~(-1) three discharges. The experiment showed that vegetation dam can cause backwater of upper reaches and reduce flow velocity. After add in sediment, bed load sediment's kinematic velocity of upstream is reduced obviously. And it makes much coarse-grained sediment deposit before the dam. This shows that vegetation dam can retard water and sediment. In the process of transportation, sediment group leading end appears triangle distribution at first. And when more and more it nears the dam body, the triangle distribution disappears gradually. This shows that backwater and velocity gradient change the feature of sediment transportation. And it proves that base slope has prodigious influence on the feature of sediment transportation and sediment kinematic velocity. Finally, we analyzed theoretically the relations between inlet section sediment discharge and bed load sediment's kinematic velocity of upper reaches before the dam.

Abstract: The infulence of sediment-laden flow on bed material composition of the active layer in the process of degradation and aggreagtion are considered to be composed of two parts with different sacle and mechanism. One is the turbulence burst taken place on the bed surface inducing the exchange between the sediment carried by flow and those setting on the bed surface. The other is the periodical deformation of the bed forms, especially the sand waves, which causes the mixing of bed material within the active layer. The equation describing these two processes is derived on the basis of mass conservation in the active layer.The variables of the equation are decomposed into two parts, one is corresponding to the average movement of sediment in active layer and the other one is corresponding to the disturbance due to bed form deformation.This partical difference equation appears to be a diffusion equation with source term.The application of the proposed equation to a simplified case of bed degradation is presented.The result shows it is reasonable.

Abstract: Zhutuo and Cuntan gauging station are the main reference points into Three Gorges Reservoir. The survey data of gravel bed load in Cuntan station from 1996 to 2001 and Zhutuo station from 1975 to 2001were analyzed. It was found that the bed load transportation has decreased systemically, the sediment granule diameter has become smaller, the sand starting flow velocity has aggrandized and the relation between flow and sand has changed obviously in Cuntan station since 1981 and Zhutuo station since 1991. Finally, it was concluded that the variations be caused by more sediment excavated from the watercourse and more water works block and keep water and soil from running off.

Abstract: Most computer models used in the flood risk analysis of rivers have inadequate functions in its spatial analytical capabilities and without sediment transport simulation capacity or suitable equations to represents correctly in-situ hydraulic processes. As a result, the current research presents the development of a new total bed material load equation using multiple linear regression analyses that is applicable for rivers in Malaysia. It was developed and embedded as a modified version of HEC-6 model and named SEDFlood model. The model is best suited for rivers having uniform sediment size distribution with a d50 value within the range 0.37 mm and 4.0 mm and performs better than the commonly used Yang, Graf and Ackers-White total bed material load equations. A user-friendly, menu-driven GUI for two and three-dimensional (2D & 3D) digital floodplain delineation was developed through ArcView GIS and SEDFlood tight coupling procedure. It is capable to produce quick analysis (snapshots) at any desired discharge time steps in flood risk mapping procedure. Field measurements were carried out to validate the hydraulic setting and the accuracy of model outputs. The feasibility of simulating a flood event along a river channel and floodplain was tested for Pari River catchment’s area located in Perak, Malaysia. Flood risk analysis were conducted for the design flood events for 10, 50, 100-year Average Recurrence Interval (ARI). The design rainfall duration of 30, 60 and 120 minutes for the present and future land use conditions (year 2020) were considered in the simulation scenarios. The result of this research indicates that GIS is an effective environment for floodplain analysis and its integration with hydraulic model is not only feasible but also mutually beneficial for both GIS users and hydraulic modelers.

Abstract: On the basis of the physical background that bed loads exchange with bed materials and suspended sediments mainly exchange with bed loads, this paper uses Einstein's bed load theory to characterize the initiation motion of bed material and bed load transport, uses Lane and Kalinshe's theory, in which river bed sands are entrained into suspension by vertical flow fluctuations, to describe the process of the lifted bed sands coming into suspension motion, suggests a thickness of bed layer, and finally establishes a formula for suspended sediment equilibrium concentration at near-bottom reference level. The present formula is calibrated with data set measured. It is verified by independent field data and flume test data, and the accuracy of the prediction is in an acceptable range. Based on the present definition of thickness of bed layer and the formula for equilibrium sediment concentration at it, this paper also gives a calculation method for suspended load transport, and this method gives a satisfactory accuracy in verification. As for suspended load transport of fine sand with a diameter less than 0.1mm, the present method overcomes the limitations of Einstein's one.