| The basic laws of flow and sediment transport have been studied by using of a lot of measured sediment transport data, and a lot of theories and methods which both have theory basis and practical value have been proposed. The main contents and results of this paper consist of the following aspects.1. The sediment transport database has been put up. This database include 9112 sets of experimental data and 6013 sets of natural river data. Compared with existing sediment transport database, the database of this paper have more data sets than others.2. Five basic problems, which relate with sediment transport, have been discussed. First, based on the definition of bed material load and wash load, new method which delineating bed material load and wash load has been proposed. Secondly, based on the discussion of condition of sediment incipient motion, the dimensionless unit stream power at sediment incipient motion is put up, so that the theory of sediment incipient motion become more integrated. Thirdly, the problem of sediment transport states is discussed. By comparison of sediment transport laws in different sediment transport states, it is proposed that sediment transport laws in different sediment transport states are similar. Fourthly, the relationship between model of variation of "k" and model of Coleman in velocity distribution of sediment-laden flow is derived from theories, and the model of variation of "k" in velocity distribution of sediment-laden flow is further studied. It is believed that the value of "k" is varied in depth, so the model of variation of "k" can be used in full depth including near-bottom area. Fifthly, based on the consideration of sediment diffusion because of sediment particle interaction, the equation of vertical distribution of sediment concentration is derived.3.The calculation of sediment transport intensity has been studied. The precision of sediment transport equations is decided by choice of measures of flow intensity. Based on the analysis of existing flow intensities, a unified flow intensity index, which can summarize shear stress, mean velocity, power, et al., has been proposed, and the relationships between various flow intensities and measured sediment transport intensity, has been compared. A generalized sediment transport equation, which can derive various existing sediment transport equations, has been proposed. Meanwhile, calibration and verification of this generalized equation is done by using of a lot of measured data. The precision of 31 sediment transport equations, have been compared by using more than 5000 sets of measured data. The results show that among these equations, equations of this paper, Karim-Kennedy, Engelund-Hansen, Ackers-White, Brownlie, Peterson-Peterson, Basson, Yang, Wang Shiqiang, et al., are the most recommended equations.4. The movable-bed resistance problem has been studied. The methods of calculating movable-bed resistance have been studied from two methods. First, total resistance is derivedby summing different resistance components. The relationship between resistance of still plane bed and energy slope has been proposed from the similarity between sediment incipient motion and still bed resistance. And this relationship can be used in computing grain resistance. The additional resistance caused by sediment transport of bed-load and suspended load is derived from mean energy equation of sediment-laden flow, and the variation of resistance in sediment-laden flow is discussed. By introducing the resistance equations of sand wave by others, the total resistance can be computed. Secondly, the total resistance is studied directly. The relationship between total stream power and effective stream power is proposed by analogizing the method of Engelund. The precisions of 23 movable-bed resistance equations, which contain the equations of this paper, have been compared by using near 10000 sets of measured data. The comparison is between predicting flow depth and measured flow depth when given unit discharge, energy slope...
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