Abstract:

On the basis of wetland hydrology,the minimum ecological water demand in three different periods was investigated for the Dongting Lake,a typical riverconnecting lake in China.The results showed that:(1) the minimum ecological water level was 24 m in either 1974 or 1988,but 246 m in 1998;(2) the minimum volumes of ecological water storage were 2106×108, 1804×108 and 1880×108 m3 in 1974,1988 and 1998,respectively;(3) the average minimum ecological water demands of lake outflow were 3 396,3 379 and 4 717 m3/s,and the minimum ecological water demands of lake inflow were 2 657 、2 704  and 3 745 m3/s in 1974～1987,1988～1997 and 1998～2007,respectively.Therefore,along with lake succession,the minimum ecological water level was significantly increased and the minimum ecological water demands of lake outflow and lake inflow were imbalanced in creased,but the minimum volume of ecological water storage was significantly decreased in 1998 compared with 1974.Finally,the re〖JP2〗asons for the changes of the minimum water demand were analyzed,and the strategies for ecological restoration were also provided