In Tempe, Ariz., a city of about 182,000 people, a complex system of inflatable dams constructed along a usually dry stretch of the Salt River has created a 2-mile-long lakeside district.

The city demonstrated how reusable dams, inflated with water, can block floods caused by heavy rainfall. (NY1/Ari Ephraim Feldman) City’s latest plan to face down flooding: Inflatable dams ...