鄱阳湖水位多时间尺度动态变化特性分析

RESEARCH ON MULTI-TIME-SCALE DYNAMIC CHARACTERISTICS OF WATER-LEVEL FLUCTUATION OF THE POYANG LAKE IN CHINA

利用鄱阳湖湖口、星子、都昌、吴城、棠荫和康山水位站多年逐日水位资料,采用统计分析法、趋势分析法、Mann-Kendall非参数检验法和Morlet小波分析法分析了鄱阳湖水位年内变化特征、年际变化趋势、极值变化、突变特征及其周期性。结果表明:鄱阳湖水位在年内具有高动态变化的特征,月最高水位一般出现在7月份,平均水位为17.75 m,最低水位一般出现在1月份,平均水位为10.8 m,年内变化幅度达6.95 m;鄱阳湖水位在多年尺度上呈现微弱的下降趋势,但是自2003年以来下降幅度较大,并多次出现极低枯水位;按年代际来对比,则2000年以后的平均水位是所有年代中最低的;鄱阳湖日、月、年最高水位出现在1954年和1998年,年最低水位出现在2011年,月和日最低水位出现时间不一致,但都主要集中在2003年之后;鄱阳湖水位有2个比较明显的突变点,即1965年附近和2006年附近,其中都昌站突变前后最大水位差达到了1.3 m;鄱阳湖水位受多种因素的影响,并没有表现出明显的周期特性,只在28时间尺度上表现出微弱的周期特性。

The natural hydrological rhythm has been altered under the combined effect of climate change and intensifying anthropocentric activities during the past decades at Poyang Lake, the largest freshwater lake in China. The main objective of this paper is to analyze the change process of water-levers at different time scales. In this research, the fluctuation characteristics of water-lever, such as monthly changing feature, annual variance tendency, extreme values, saltation feature and periodicity, were evaluated by using statistical analysis, trend analysis, Mann-Kendall non-parameters test and wavelet analysis methods based on the observed daily water-level time series from Hukou Station, Xingzi Station, Duchang Station,Wucheng Station, Tangyin Station and Kangshan Station at Poyang Lake. The main findings are shown as follows： the water-level drastically fluctuated during months and the highest water level（17.75m） and lowest water level（10.8 m）generally appeared in July and January, respectively, with an amplitude of 6.95 m; although the water-level presented a feeble downward trend during the past decades, a rapidly descending amplitude occurred after 2003, accompanying extremely low water level situation; there are three obvious saltation points at 1955, 1965 and 2006, and the maximum water-level variation is close to 2 m; periodicity, effected by many factors, is inconspicuous only with a weak periodic in 28 time scale. Results of this study demonstrate the change situations of water-level at Poyang Lake in annual and inter-annual,which will provide instruction for water security associated with flood control, drinking water usage and water ecology in the lake basin. Furthermore, the results can be applied as a foundation for drawing scheduling rules of reservoirs.