【摘要】 利用小波分析方法对1951￣2004年大通站系列水、沙和流域降水资料进行周期性和趋势性分析,利用Arc-GIS软件对长江三角洲海图进行滩涂面积计算和冲淤剖面分析,并于2002年5月￣2005年7月在长江三角洲前缘的南汇岸段进行逐日潮滩高程测量,以进行三峡水库蓄水前后滩面冲淤的对比。结果表明:尽管气候变化导致流域平均降水量以及大通径流量和输沙率存在2￣3年和8￣9年的波动周期(P<0.05),但大通输沙率从1960年代末开始出现明显的下降趋势(P<0.001),三峡工程运行后的2003年(6月开始蓄水)和2004年连续2年创历史新低,流域水库的修建是导致这一下降趋势的根本原因。长江来沙量的锐减正在导致三角洲前缘滩涂从淤涨向侵蚀转化。预测认为:流域人类活动还将继续导致长江入海泥沙量的下降,今后几十年的大通输沙率将从目前的1.5×108￣2×108t/a下降到1×108t/a左右;泛长江三角洲海岸滩涂资源将面临严峻挑战。更多还原

【Abstract】 The periodicity and trends of 1951-2004 time series of water and sediment discharges at Datong Station and precipitation in the catchment were analyzed using wavelet method. Bathymetric data were processed for coastal area and profile using Arc-GIS software. A typical intertidal flat was daily measured from May 2002 to August 2005 for comparison of bed level between pre- and post-impoundment of the Three Gorges Reservoir. The results indicate that the sediment discharge shows a decreasing trend from the late 1960s (P < 0.001) while it varies in periods of 2-3 years and 8-9 years together with water discharge and precipitation. The decreasing trend is attributed mainly to dam construction while the periodicity is attributed to climate variability. After the impoundment of the Three Gorges Reservoir, the sediment discharge was reduced to the lowest level in the history. As a result of the drastic decrease in riverine sediment supply, the delta is transforming from progradation to recession. The sediment supply from the Yangtze is forecasted to decrease from 1.5×108-2×108 t/a at the present to -1×108 t/a in the coming decades, which will result in crisis of coastal resources.更多还原