Pebble sampler suitable for small and medium river bottom boundaries

The utility model discloses a bottom boundary pebble sampler suitable for small and medium rivers. The bottom boundary pebble sampler comprises a bottom plate, a bottom side plate, a sampling side plate, an empennage, an upper longitudinal rod, a circular cross beam, a middle cross beam, a lower cross beam and a rear cross beam. The device has the beneficial effects that the lead blocks are reasonably increased and decreased according to different water flow and water depth conditions, so that an included angle of more than 10 degrees is formed between the low front part and the high rear partof the device body and the riverbed plane, the front edge declination teeth of the mouth door are smoothly inserted into the riverbed boundary and are stably ploughed on the riverbed, and then a sandy gravel sample in a certain depth can be collected; by adjusting the proper weight of the instrument, the testing safety is greatly improved when no high-horsepower measuring wheel exists in medium and small rivers; the samp