Comparison: US P‐61 and Delft Sediment Samplers

Abstract

The US P-61 suspended-sediment sampler has an electrically operated valve in the nozzle and samples isokinetically the entire mass of water and sediment entering its nozzle. The Delft Bottle (DB) is a continuous flow-through device that collects by deposition most of the coarse sediment entering its nozzle but allows the water and finer sediments to pass through it. The minimum size of particle that deposits in the DB increases with increasing stream velocity. When the samplers were compared on the basis of computed total sand transport (material > 0.062 mm), the transport rates computed from samples collected by the P-61 were about twice those of the DB. DB transport rates in the 0.062–0.125 mm size fraction were much lower than P-61 rates for the same size. In the 0.125–0.250 mm size fraction, the DB and P-61 rates were nearly equal for transport, less than 200 g/m