the inflatable flexible membrane dams (ifmd, or rubber dams) were developed in the early 1950s - flexidam - imbertson. they are installed in stream and river beds, generally being bolted into a concrete foundation. they are used to divert water for irrigation, temporarily raising existing dams, flood control, water retention for aquifer recharge, reducing or preventing salt water intrusion into fresh water areas, protect low-lying coastal areas from tidal flooding, enabling fish passage past diversion works, by deflation, and for sewage retention/separation during flood events.