Improved Guidelines for the Use of the Rising Air Float Technique for River Gauging

The rising air float technique is a method of river discharge measurement involving the release of air bubbles from a perforated pipe laid across the bed of a river. This paper describes field and laboratory analyses which seek to extend previous work and to assess the potential of the technique as an alternative for conventional methods of spot and continuous gauging. The results have confirmed that the technique is a cheap, accurate and robust alternative to other methods of spot gauging, and is sensitive to the operating pressure, with a value of 10 psi producing an optimum bubble envelope at the surface. A major constraint to the implementation of the technique for continuous monitoring remains the procedure for automatic processing of a photographic image of the bubble envelope. Guidelines are presented for the optimum configuration of equipment for both spot and continuous gauging.