1954—2013年太湖水位特征要素变化及成因分析

Changes and cause analysis of water level characteristic factors in Taihu Lake during period from 1954 to 2013

采用1954—2013年的逐日水位资料,系统分析和比较了太湖年内最高水位、最低水位及年平均水位共3种水位特征要素的年际变化规律,结合太湖流域降水资料和工程引水资料,揭示了导致三者发生阶段性变化的控制性因素。结果表明:(a)1954—2013年,太湖年内最高水位总体上不具有显著的变化趋势,其年际变化主要受控于汛期降水的年际周期性振荡;太湖年内最低水位、年内平均水位均具有显著的上升趋势,尽管两者在2000年之前的年际变化主要受控于太湖流域降水丰枯振荡,但在2000年之后的"引江济太工程"等大规模引水活动已成为两者在流域降水整体偏枯情况下仍保持较高水平的主导性因素。(b)沿江引水使太湖的年内最低水位出现时间的季节性分布特征发生了明显变化。

Based on daily water level observations of Taihu Lake during the period from 1954 to 2013, changes of three water level characteristic factors, including the highest annual water level, lowest annual water level, and mean annual water level, were analyzed and compared. In combination with rainfall and water diversion data from the Taihu Lake Basin, the dominant factors driving the three water level characteristic factors are illustrated. Results showed that changes of the highest annual water level were not significant during the period from 1954 to 2013 and its inter- annual variation was mainly controlled by the inter-annual periodic fluctuation of flood season precipitation in the Taihu Lake Basin. However, the lowest annual water level and mean annual water level of Taihu Lake were increasing significantly, with their inter-annual variations mainly controlled by the precipitation fluctuation in the Taihu Lake Basin before 2000. After 2000, their inter-annual variations were mainly controlled by the massive water diversions, such as the water diversion from the Yangtze River to Taihu Lake, maintaining high levels of the lowest annual water level and mean annual water level in spite of less precipitation. In addition, water diversion from the Yangtze River to Taihu Lake causes significant changes of the seasonal distribution characteristics of the occurrence time of the lowest annual water level of Taihu Lake.