Long-term trend analysis of effect of the Yangtze River on water level variation of Poyang Lake (1960 to 2007)

Abstract

The Poyang Lake water level is heavily influenced by the watershed inflows and also by the Yangtze River from the north of the lake basin. Observed river discharge and water level from the Yangtze River and the Poyang Lake catchment are used in this paper to further investigate the variation of the Yangtze River (blocking) effect on the change of Poyang Lake water level. The preliminary results indicate that the strong Yangtze River effect shows a long-term decrease trend according to the increase of warm season rainfall in the Poyang Lake basin. Poyang Lake water level increased obviously during 1960–2000, however, the pattern of annual lake water level variation was somewhat altered due to the modifications to the river-lake interactions caused by various reasons, especially after the completion of the Three Gorges Dam (TGD) project in 2003. In accordance to the regulation of the Three Gorges Reservoir, the Poyang Lake water level varied correspondingly with decrease in October-December and slight increase in January-March. In particular, the operation of the Three Gorges Dam project may promote an earlier coming of low water season for Poyang Lake, and aggravate water supply in the lake area, especially in dry years.