“…Difficult terrain and climatic conditions, high variability of bedload transport, and problems with estimation of measurement efficiency make it difficult to apply modern, direct, and continuous monitoring methods such as: luminescent, magnetic, radio-emitter, radioisotope, or acoustic method [e.g. 9, [16][17][18][19][20][21][22][23][24][25][26][27]. Due to the short term and spot character of measurement, application of Helley-Smith samplers can also result in low representativeness and limited measurement efficiency, particularly in the case of medium-and coarse-grained fractions [22,28,29].…”