Measuring Bed Load Transport Rates by Grain-Size Fraction Using the Swiss Plate Geophone Signal at the Erlenbach

The Swiss plate geophone system is a bed load surrogate monitoring technique that is used to quantify bed load transport in steep streams. The amplitude of the signal recorded by the Swiss plate geophone contains information about the grain-size distribution of the transported bed load. To extract this information, the authors computed the number of impulses and packets (representing a single particle impact) registered for different amplitude ranges, the so-called amplitude histograms, for 46 samples when bed load was measured independently with automatic basket samplers at the Erlenbach. Amplitude histograms can be interpreted as a statistical distribution of the signal's amplitude over a given time interval. Using the number of bed load particles per unit mass, absolute bed load masses for each grain-size class can be calculated. The results show that the grain-size distribution of the transported bed load for particles larger than 9.5mm can be continuously monitored at the Erlenbach with the Swiss plate geophone system. (C) 2016 American Society of Civil Engineers.