The USFS Portable Bedload Trap was developed for representative sampling initiation of gravel motion and coarse bedload transport rates in wadable gravel and cobble bed mountain streams. The trap is 0.3 m wide, 0.2 m high and has a 0.9 m long trailing net with a 3.5 mm mesh width. The trap can be quickly installed on a stream bottom with little disturbance of the bed and can be operated by 1-3 persons over a wide range of flow. For sampling, the trap is temporarily fastened onto ground plates anchored into the stream bottom. Usually the traps are deployed in sets of 5 to 6 traps on riffles or runs in mountain gravel-bed streams. Sampling time is usually one hour and facilitates representative samples of a wide range of transport rates (up to 7 orders of magnitude) and bedload particle sizes (4-90 mm). This capability for representative sampling provides valuable bedload data-sets suitable for performing initial motion computations.
E-504-406-001 USFS Bedload Trap 8 lbs.