URBAN FLOODING

Nuisance flooding of streets, underpasses, basements and other low-lying urban areas. Should not be confused with flash flooding. Usually due to poor drainage, or limited drainage capacity of urban systems. The amount and rate of precipitation that causes urban or Small Stream Flooding is usually constant for a specific community. In general, 0.5-1.0 inch (1.3-2.5 cm) of precipitation in one hour will cause at least minor urban/small stream flooding in most urbanized areas. Over one inch of rainfall in an hour will cause general urban flood problems, and may cause flash flooding.