Study On The Channel Regulation Of Santan In Xi Jiang Under Influence Of Tides

We desperate need a combining transportation to improve the economy of the pear cities around the river and to develop a mutual improvement of economy of earas which locate around river and sea.finally,we can make a direct transportation from river to sea by this mean. Riverbed of Xijiang's main stream from Wuzhou to Yunan, about 45 kilometers, is mainly sandy and stoney. For the construction of hydro junction upstream on Xijiang, this changed the conditions of stream and sand in it, which caused (), water surface broaden, riverbed getting wide and shallow, main stream swinging, dredged channel changed several times, riverbed becoming quite unstable and evolving rapidly, dangerous shoal getting more, such as Jilongzhou, Jieshou(Dayuanchong, Qicha and Liaotang), Santan(Panlong, Xintan and Dule) and etc. Santan locates on the end of tidal reach edge, and has come under the influence of construction of hydro junction upstream, as well as has a complicated boundary conditions on sand, water and riverbed. This becomes the choke point on the development of Xijiang.The main reasons that tidal reach riverbed changes are unbalance conveying of sand and interaction among tide, radial flow and riverbed. The rinsing silt of reach and how shoal come into being have something to do with degree and direction of rising and ebb tide. The main factors that influences evolving of riverbed are sand and water conditions of reach entrance and exit, conditions on geology and physiognomy of reach and the relationship between water level and flow rate on the fault surface of the reach's exit. Tidal reach has a complicated movement between stream and silt, and the influence on tide varies from part to part. So the analysis of tidal reach evolving should comprise the upstream and downstream with current reach and consider them as a whole. Some reach's reshaping may influence the upstream and downstream nearby.Currently, there are three kind of method on channel regulation research: Analyses of channel regulation, experiment on physical model and numerical simulation calculation. This article take advantage of theory on hydraulics, fluvial (costal) dynamics and interrelated subjects, fixed the water undertaking's hydrology and silt feature, exploit tendency of history, recent and future evolution of topography, as to provide a scientific dependencies for feasible evaluation; begin with movement equation of water and silt, according to the similar theory, expound the discipline that still and motional riverbed model should obey. Design the current channel model, and experiment on still and motional riverbed model. Analyze the result obtained, compare each scheme with its advantage and disadvantage, and optimize each scheme.