Study on evolvement law of urban flood disasters in China under urbanization

Based on the national flood disaster data from 1990 to 2015, the evolvement characteristics of the urban flood disasters and the relationship between Chinese flood disaster and urbanization rate were explored mathematical statistics, GIS technology, gray correlation analysis and other methods. The results indicate that the urban flood disasters in southern and mid-eastern China were more serious than those in the northern and western regions. Cities suffering frequent floods were mainly distributed in the Yangtze River Basin and the Pearl River Basin, especially among the urban agglomerations of the middle and lower reaches of the Yangtze River, Chengdu-Chongqing region and the Pearl River Delta. With the rapid urbanization in China, the total number of urban flood disasters decreased first and then gradually increased. Meanwhile, the frequency of flood disasters dropped in the north and rose in the south. The interannual affected and dead population due to urban flood disasters had great and occasional variations, whereas both had a decreasing trend in general. However, economic losses have generally rose over the time. It was shown that the dead and affected populations and direct economic losses were strongly correlated with the urbanization rate.