From the perspective of historical geography, the flood disasters of the middle reach of the Yangtze River results from the defect of its landscape and watersystem, the deterioration of its ecological environment, and the weakness of th e ability of its dykes to resist floods. In comparison with the past times, at present many large reservoirs to some extent have remedied the natural defect of its landscape and watersystem, but in the meantime, its ecological environment has been further deteriorated and the ability of its dykes to resist floods has still been rather weak, so that the ecologic...
