Analysis on flow and sediment transportation variation of the Poyang lake into the Yangtze lake

By the flow and sediment observation data at Hukou hydrologic station from 1956 to 2005,the variation law of flow and sediment transportation of the Poyang lake into the Yangtze river in decades,overyears and seasons are analyzed.The research demonstrates that: ① The flow volume of the Poyang lake into the Yangtze river varied obviously,increasing obviously in 1990s and decreasing in the 21th century;the sediment transportation volume into the Yangtze river had a obvious increment tendency from 1950s to 1990s and a obvious decrease tendency in the 21th century.② In different years,the variation amplitude of flow and sediment transportation into the Yangtze river is great and the variation amplitude of sediment transportation into the Yangtze is greater than that of flow.③ The seasonal variation amplitude of flow and sediment transportation into the Yangtze river is obvious,the flow into the Yangtze river is mainly in flood season from April to September,which reaches over 68% of annual runoff.For the inversed flow of the Yangtze river into the Poyang lake, the variation of the Poyang lake sediment transportation into the Yangtze river is not in accordance with the flow into the Yangtze river,the sediment transportation is mainly in spring and autumn,especially in intermittent period of the Yangtze river flood season and the Poyang lake flood season from March to May.④ The correlativeness of annual sediment transportation and annual runoff is low,but the variation consistency of the flow and sediment transportation into the Yangtze river from dry season to pre-period of flood season is good.