At-Stream-Velocity Pumping Sediment Sampling System

The sampling system collects water-sediment samples at local stream velocity from any point in an open channel flow. The system uses a flow-through Pitot tube as a combination velocity sensor and sampler nozzle. The main advantage of the sampling system over existing suspended sediment samplers such as the US-P series samplers is that a sample of any desired volume can be collected without changing the position of the sampler nozzle. To compare the performance of the system with that of other samplers, suspended-sediment samples were collected from a flat-bed flow using the system, a US DH-48 sampler modified for point sampling, and a siphon sampler. On the basis of these samples, at the 99% confidence level, the relative percent difference between the concentrations of the samples from the system and the siphon sampler was between -5.45 and 4.45 and the relative percent difference between the concentrations of the samples from the system and from the US DH-48 was between -0.54 and 7.78.