“According to National Weather Service data, freshwater flood losses in the United States amount to nearly $8 billion a year over the past three decades—as if the damage from a very bad hurricane were spread throughout the country. Even during tropical cyclones, however, 2 in 3 flood insurance claims relate to freshwater flooding, not storm surge. Some flooding comes from swollen rivers or occurs on low-lying properties. But a surprisingly large degree of rainfall damage, based on local case studies, appears to be determined by man-made landscapes of asphalt, concrete, and iron. After scanning reports from local NWS field offices, the authors believe that the nation experienced some 3,600 urban flooding events in the past 25 years—about one every two to three days.”
— Slate