Rubber dams are long tubular-shaped fabrics placed across channels, streams and weir crest to raise the upstream water level when inflated. The membrane is a multi-layer fabric made of synthetic fibre which may be rubberised on one or both
sides, and possibly coated with plastic film. The fabric is quite flexible and yet exhibits very large resistance characteristics. The inflatable flexible membrane dams were developed in the early 1950s. In open channels, they are used to divert water for irrigation, for raising existing dams, for flood controls. Other applications include remedy measure to prevent dam overtopping and control of chemical spills in streams. Inflatable dams can be filled with water, air or both. The present trend s ests an increased use of air-filled membranes because they can be deflated or inflated more rapidly, and they are little affected by freezing conditions. Characteristic dimensions cover typically lengths of about 100 m with specially-made membranes up to 200-m wide, dam heights usually less than 5-m but some special designs might be up to 10-m high. The membrane is usually deflated for large overflows.
Low cost compared to other controllable gates