Analysis of Causes of Waterlogging Disasters in Nanjing City

In recent years,with the acceleration of urbanization process in Nanjing,the city waterlogging disasters become more and more serious.The theories of hydrology,geography and planning are applied to analyze the causes of waterlogging disasters in Nanjing City.The natural and geographical environment of Nanjing is very special.Urbanization leads to the reality that the annual precipitations,flood season precipitations and frequencies of rainstorm of Nanjing City have been increasing.The change of the urban underlying surface condition leads to the increase of surface runoff and the decrease of conflux time.Inadequate urban planning reduces the enduring ability of the city for waterlogging disasters.Urbanization aggravates the damage degree of waterlogging.All these are the main reasons that cause the waterlogging disasters of Nanjing City.