描述：The Poyang lake is currently the largest freshwater lake in China. Hydrologic properties of this lake, including precipitation, runoff, flood, sediment transport and so on have been analyzed on basis of large amount of measurements. Variation of these properties within a year and among years and the regional distribution are explored. The encounter probability of the outflow from Poyang Lake with that from Changjiang River is computed and the detention volume of Poyang Lake is analyzed. In accordance with water balance theory, the detention storage volume of Poyang Lake and Changjiang River corresponding to the annual maximum 60-day flood volumes in 9 typical heavy flood years of 1968, 1969, 1973, 1980, 1983, 1996 and 1998 have been calculated. The detention storage capacity of both the Lake and the River ranges from 5.6 billion to 16.5 billion m\+3, 11.5 billion m\+3 at average. Among which, the detention storage capacity of Poyang Lake is 9.5 billion m\+3, accounting for 82.6%. Poyang Lake has played a very important role in detaining floods from the five rivers of the Lake system as well as floods on the river section from Changjiang to Bali. There would have more frequent and more serious flooding on the middle and lower Changjiang River, especially in the region around Hukou if there were no Poyang Lake to detain and store the floodwater.
全文：The Poyang lake is currently the largest freshwater lake in China. Hydrologic properties of this lake, including precipitation, runoff, flood, sediment transport and so on have been analyzed on basis of large amount of measurements. Variation of these properties within a year and among years and the regional distribution are explored. The encounter probability of the outflow from Poyang Lake with that from Changjiang River is computed and the detention volume of Poyang Lake is analyzed. In accordance with water balance theory, the detention storage volume of Poyang Lake and Changjiang River corresponding to the annual maximum 60-day flood volumes in 9 typical heavy flood years of 1968, 1969, 1973, 1980, 1983, 1996 and 1998 have been calculated. The detention storage capacity of both the Lake and the River ranges from 5.6 billion to 16.5 billion m\+3, 11.5 billion m\+3 at average. Among which, the detention storage capacity of Poyang Lake is 9.5 billion m\+3, accounting for 82.6%. Poyang Lake has played a very important role in detaining floods from the five rivers of the Lake system as well as floods on the river section from Changjiang to Bali. There would have more frequent and more serious flooding on the middle and lower Changjiang River, especially in the region around Hukou if there were no Poyang Lake to detain and store the floodwater.