The Study Of A New Estimated Method Of Sediment Scouring And Silting In The Downstream Reach Of The Dam

Sediment deposition is a vexing issue all the time. The key lies in the variability and complexity of it. The affecting elements of sediment deposition are often various.Broadly speaking, it changed the flow-sediment conditions, channel forming discharge and flow fluvial effect of downstream after the completion of the hub. In small ways,the affecting elements of sediment deposition include velocity, depth, gradient, gravity,viscosity, effective unit weight, settling velocity, particle size, the composition of bed material, river width and so on. According to the development tendency of water resource, it is inevitable to adopt laddering layout in the river. After the change of downstream original flow-sediment conditions, how to estimate the situation of sediment silting appears especially important, which will offer a reliable gist for upper sediment deposition analyze.After the completion of the hub, sediment-carrying capacity of water discharge will greatly decrease during an interval of time. It will experience a long-time erosion process and then reach relatively balance. Then, we can analysis the silting situation based on sediment-carrying capacity of flow. Sediment-carrying capacity of flow is an important issue in research field of sediment. It involved sediment transportation,pollutant dispersion, coastal evolution, scouring and silting in bed, and some other problems. From the research situation at home and abroad, most of the formulas of sediment-carrying capacity of flow are the extension of Zhang Ruijin’s. Also these formulas mainly aim at specific river. The main reasons for this phenomenon are people didn’t completely control some tensile mechanism of sediment- carrying capacity of flow and we didn’t reach a consensus of conclusive in the elements that affect sediment.This paper consults the tensile mechanism analyze for lower reach sediment deposition by famous scholars, and then ensuring the key influencing factors of sediment-carrying capacity of flow, after that, adopting perturbation theory to analysis the key influencing factors of sediment-carrying capacity of flow. At the same time,collecting measured data of representative rivers at home and abroad. Then using the methods of dimensional analysis and multivariate linear regression combining with least square method to match the measured data and derive a new formula of sediment-carrying capacity of flow. After the process of derivation, we verify the formula by measured data and flume test data. Last, estimating the situation of sediment deposition by the derived formula and the estimated method with measured results andthe physical model results. At the same time, analyzing the situation of sediment deposition by numerical model. Compared the estimated results with measured results and numerical model results to make further ion on the availability of the derived formula. The main achievements are as follows:(1)Briefly review the predecessors’ researches of sediment-carrying capacity of flow and sediment deposition of downstream. Summarizing the analysis on tensile mechanism of sediment-carrying capacity of flow by them. Putting forwards the advantages and disadvantages in their process of researches and then coming forward the solutions preliminary.(2)By adopting perturbation theory, dimensional analysis, multivariate linear regression and least square method to derive sediment-carrying capacity of flow. Using measured data of representative rivers and flume tests result at home and abroad to verify the derived formula. Compared the verified results with other common formulas,and judging the reasonability of derived formula.(3) Based on the derived formula, a new estimation method of sediment deposition is presented. Then use the new method to analysis the siltation of total 19 km river in the downstream of Baishiyao Hub.(4)Estimating the sediment deposition by derived formula with measured results and physical model results in the 19 km downstream below the Baishiyao dam. Also analyzing the sediment deposition by numerical simulation of the same area. Compared the estimated results with the results of measured(tests result) and numerical simulation.According to the comparison results, the error between the estimated sediment deposition(tests result) and result of numerical simulation is not large, all of which are within the error range. It shows that the derived formula is reasonable in theory and the new calculated method has certain feasibility, it can offer a reference for sediment erosion and deposition analysis of the engineering, but whether fits for other rivers needs a further verification.