Modelling bedload particle travel lengths in rivers with different hydrologic regimes

A universal model between gravel particle displacement distance and flow strength has been elusive. In this study, we hypothesize that such a relation is possible through a more consistent methodological approach consisting of: 1) testing 17 different flow metrics, 2) treating each tracer size class as a separate population and calibrating the critical bed shear stress of each size class using field data, 3) scaling tracer travel lengths by the mean channel width, and 4) controlling for tracer slowdown within our dataset. Following these methods resulted in strong linear relations between the scaled mean tracer travel length and both the cumulative excess discharge (R2 = 0.90) and the cumulative excess total stream power (R2 = 0.91). These results confirm that a single relation between flow and bedload particle displacements in rivers with different hydrologic regimes is possible.