In-situ checking the performance of bed-load samplers by underwater video

摘要

The process of bed-load transport and the performance of two sampler types (Karolyi and Helley-Smith) were studied in the field with the help of an underwater video camera mounted on the sampler's body. The phenomenon was viewed on board of the measuring vessel on the monitor of a video recorder connected with the camera. Effective sampling was restricted to part of the total measuring time. The rates of bed load transport obtained with the actual sampling time were more reliable than those calculated with the total time for which the sampler rested on the bottom. The main reasons for poor effectiveness were imperfect support of the sampler on the bottom and the high hydraulic resistance caused mainly by clogging of the wire mesh basket in which the trapped sediment was collected.