| Field comparisons of sampling characteristics of six pressure-difference bedload samplers, modeled after the Helley-Smith bedload sampler, were made in a natural stream having turbulent, high-velocity flow and high bedload transport rates. The samplers have intake nozzles with entrance dimensions (width and height) ranging from 76 x 76 millimeters to 305 x 152 millimeters and include nozzle area expansion ratios of 1.40 and 3.22. Hydraulic efficiencies of the bedload samplers range from 1.35 to 1.54. Two of the sampler nozzles were also tested with modified sampler frame and tail configurations. Data from thirteen field tests were used to compare bedload samplers. -- Childers, 1999 |
