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一、汉江下游洪水灾害概况汉江自湖北省锺祥以下通称下游。下游河道全长380公里,集水面积32,000平方公里,为一广大平原区(包括16个县及武汉市),共有耕地 1,280万亩,人口724万,是一个经常遭受洪灾威胁的地区。据统计,该区受汉江于流洪水威胁的总面积(包括东荆河右岸部分地区)约为15,000平方公里,内有耕地800余方亩,人口410万,是长江中游洪水灾害严重地区之一。下游河床为两岸堤防所约束,沿河泄洪能力愈向下游愈小,与中上游(集水面积计有142,000平方公里),汇来的洪峰流量不相适应。小洪水则造成下游堤防的下段溃决,大洪水则酿成整个下游堤
First, the Han River flood disaster in the lower reaches of the Han River from Hubei Province Zhongxiang commonly known as the lower reaches. The lower reaches of the river is 380 kilometers in length and covers an area of 32,000 square kilometers. It is a vast plains area (including 16 counties and Wuhan) with a total area of 12.8 million mu and a population of 7.24 million. It is a region frequently subjected to flood threats. According to statistics, the total area threatened by the flood in the Hanjiang River (including the part of the right bank of Dongjing River) is about 15,000 square kilometers. There are more than 800 mu of cultivated land and a population of 4.1 million. It is one of the flood disaster-hit areas in the middle reaches of the Yangtze River . The downstream riverbed is restricted by the embankments across the Taiwan Strait, and the more the flood discharge capacity along the river, the smaller the downstream reach is, which is not compatible with the flood peak flow received by the middle and upper reaches (with a catchment area of 142,000 km2). Small floods caused the lower section of the embankment downstream to collapse, while the flood caused the entire downstream embankment