Flood Water Level along the Main Channel of the Lower Reaches of the Yangtze River in the Past 40 Years： Variations and Causes

最近十年来,江苏境内长江下游干流汛期最高潮位连续偏高,持续时间亦明显偏长.造成防汛工作紧张,引起政府有关部门的重视,水利部门将治理长江作为重点工作、本文利用长江下游干流大通水文站和以下各潮位站的实测水位流量资料,对1998和1954年的特大洪水水情进行了对比,分析了从六十年代到九十年代长江下游平均洪水量、平均最高水位和平均最高潮位、超过防洪警戒水位的平均天数等的变化规律.通过对长江中、上游来水量和下游东海潮汐等影响因素分析,初步探讨了近十年来长江市游高水位频繁出现的原因.;The highest water level of the lower reaches of the Yangtze River in the area of Jiangsu Province is continuously higher and its duration is obviously longer than before during the last decade. Therefore, the flood control became heavier and heavier, the regulation of the Yangtze River is payed the important attention by central and local government. In the paper, the heavy flood in 1998 is compared with that in 1954, based on data of practical measurements of Datong Hydrologic Station in the main channel and others in its down stream. The variable regularities of the average flood volume, mean of the highest water level, mean of the highest water and the average days when the water level is over the warning water level for flood control in down stream from the 1960s to the 1990s are discussed. Through the analysis of such factors as the water volume from upper and middle reaches of the Yangtze River, the tide from East China Sea, etc., the reason of frequent occurrences of high water level in the lower reaches of the Yangtze River is approached.