Abstract
In the process of city expansion, irrational development brings about serious phenomenon, such as filling lakes to make land and occupation of the riverway, which results in shrinkage of urban rivers and lakes, decline of flood discharge capacity, weakening of water holding capacity of lakes, and reduction of areas of wetland and greenbelt. The flood control and retention capacity of the original ecosystem reduces, thus the frequency of flood disaster and extent of damage are aggravated. This article explains the close relationship between urbanization and urban flood disaster by discussing the formative factors of climate changes and urban flood disaster, and studying the formation mechanism of urban flood disaster. On the basis of studying the overall arrangement and flood control function of rivers, lakes, wetlands, and greenbelts, this article provides an idea of urban ecological flood control and analyzes the ecological flood control pattern of main urban areas of Chongqing by comprehensive utilization of GIS. The results show that the major transformation direction of main urban areas of Chongqing is transforming from cultivated land to urban construction land. Along with the completion and impoundment of the Three Gorges Project, water level of the upstream of the Yangtze River is rising continuously and there is a trend of increasing year by year in the water area of Chongqing section.