Final answer:
Urban floods are dangerous due to impeded water receding, rapid pollutant and disease spread, and the fact that many cities are in low-lying coastal areas or flood zones.
Step-by-step explanation:
Floods in urban areas are particularly dangerous due to a combination of factors. Firstly, dense urban infrastructure can prevent floodwaters from receding efficiently, exacerbating the impact of flooding. Secondly, floods in urban environments can rapidly spread pollutants and diseases, which is intensified by the high population density and often inadequate public water works and sewage systems.
Moreover, in urban settings, the presence of industrial wastes and agricultural runoff contributes to the pollution problem. Finally, many populated cities are located in low-lying coastal areas or flood zones, which heightens the risk of substantial economic losses and health hazards during flooding events.