长江中下游洪水灾害成因及洪水特征模拟分析

长江中下游地区洪水灾害的发生是自然地理条件及人类活动共同作用的结果。流域水系构造和地理特征决定了其洪水多发性，气候变化和土地利用/地表覆盖变化导致该地区水循环过程发生较大改变，而大量水库、堤防的建设以及城市化的发展使得洪水过程发生显著变化，因此在各种因素的综合作用下，长江中下游地区近年来洪水灾害频繁发生。综述了气候变化对长江中下游降水的影响，探讨了长江中下游水系特征与洪水灾害的关系，分析了人类活动对洪水灾害的影响规律，在此基础上，开展了气候和下垫面特征变化条件下的暴雨洪水模拟研究，以长江下游太湖东苕溪流域的南苕溪为研究区，进行了流域降雨径流过程的动态模拟验证和特征分析，并取得了较满意的成果，从而为长江中下游地区防洪减灾研究打下了基础。

ANALYSIS ON THE CAUSE OF FORMATION OF FLOOD DISASTER AND FLOOD CHARACTERISTICS IN THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER

The flood disaster in the middle and lower reaches of the Yangtze River is the combined consequence of its geography and human activities. The structure of water system and the geographical characteristics decide its flood-prone, and the climate variability and land use/land cover changes make the water circulation change greatly; whereas the construction of a number of reservoirs and dikes and the development of urbanization cause the flood process verified remarkably. Therefore, under the influence of these factors, the flood disaster in the middle and lower reaches of the Yangtze River occurs frequently in recent years. This paper summed up the impact of climate variability on precipitation in the middle and lower reaches of the Yangtze River, discussed the relationship between water system properties and flood disasters, and analyzed the laws of influence of human activities on flood disasters. Based on these studies, the rainstorm-flood simulation under the variational condition has been developed. We took the Nantiaoxi of Dongtiaoxi Valley as a study area to verify dynamically the precipitation-runoff process. In one word, all of the works provide the support for flood proofing and disaster reduction in the middle and lower reaches of the Yangtze River.