UBC Theses and Dissertations
Calibrating and measuring bed load transport with a magnetic detection system Rempel, Jason
A series of lab and flume experiments were designed to test and calibrate the Bed load Movement Detector (BMD), a magnetic system for measuring bed load movement in gravel bed streams. Experiments used both artificial and natural stones, and were specifically designed to isolate the effects of particle size, velocity and magnetic content on the shape of the recorded signal. Empirical relations were derived between the amplitude, width and integral of the sensor response, with particle size, velocity and magnetic content. Because of high variability in response across an individual sensor, the current system cannot be used to reliably predict the particle size from an individual signal. Results improved at the event scale, where variability averages out. Over the course of the experiments, a number of weaknesses in the sensor design were observed; these are discussed, and some suggestions are made of ways to improve the system.