Dredging operations in navigable waterways are based upon the rate of sediment deposition. The study of the rate of sediment deposition can be greatly enhanced by collecting unbiased water-sediment samples from rivers and streams.
The life expectancy of a water reservoir is determined by the rate at which it is filled with sediment from the rivers and streams that feed it. In order to determine the rate of sediment deposition in a water reservoir, it is necessary to have a means to take accurate and reliable samples from the flowing waters that feed the reservoir.
The U.S. Government is currently involved in comprehensive studies of the quality of the rivers in the United States. For the past 30 years the U.S. Geological Survey has conducted the National Stream Quality Accountingcarefully lifted out of the water and the samples removed. The major problem with the arrangement was that the bags were unprotected and had to be handled very carefully.
The Rhine Works Authority sampler consisted of a latex balloon, a nozzle, and a metal frame with a tail fin. When sampling, a pinch clamp located at the neck of the balloon was operated by an auxiliary line to allow flow into the balloon. The sampler was not streamlined, and the requirement for an auxiliary line limited the use of the sampler.
Stevens and others (Stevens et al, 1980) fabricated 1-gallon and 2-gallon samplers using plastic bags. The samplers consisted of a wide-mouth, perforated, rigid container enclosed in a cage-like metal frame attached above a sounding weight. The head of the