Analysis of water and sediment characteristics during flood and low water period of Yong River

Based on the observated data of hydrology and sediment in July,2010(flood period) and January,2011(low-flow period),tidal level,fluctuation-tide duration,velocity,tidal quantity,distribution of sediment concentration and sediment transport capacity are discussed in this paper.Ultimately,some conclusions are achieved.Firstly,the tidal level eigenvalues such as the maximum,minimum,average and extreme tidal range are little bigger during flood than those during the low.Secondly,the average flood-tide duration is longer during flood than low water period at spring tide.The average ebb-tide duration of spring tide is taken shorter time during flood.However,the law is opposite when it is a neap tide,whether it is in flood or in low water period.Thirdly,characteristics of each cross section′s mean velocity in vertical increased along the way are spring higher than neap,ebb higher than flood during flood and low-flow period.Tidal influx and flood tidal level difference are linear correlation.Finally,the characteristics of each cross section′s mean sediment concentration in vertical are low-flow period higher tean flood,spring higher than neap.And the sediment concentration distribution in vertical is Ⅱ type.A formula of sediment transport capacity of which background sediment concentration is brought into is developed during flood and low-flow period.