Abstract
Channel morphological change is often evaluated by employing sediment transport models since field data during high magnitude low frequency events is rarely available. However, sediment transport rate estimates are heuristic at best to within 1 - 3 orders of magnitude. Mimico Creek is an urban gravel-bed channel in Southern Ontario, Canada that has undergone intensive event-based sediment transport sampling and inter-event bed material particle tracking over a three-year period. A HEC-RAS model was developed of the study reach and calibrated to a series of discharge events where in-situ bedload sampling occurred. Both step-wise discharge and unsteady flow simulations were evaluated to compare sediment transport rates for a range of transport models which included the Meyer-Peter Müller and the Wilcock-Crowe. Calibration curves were developed to estimate sediment discharge in Mimico Creek. The results of the calibrated model were used to calculate the mean travel distance of bed material using the expression for the volumetric rate of bed material transport. Results from the modelling exercise found mean travel distances were similar and in some cases larger than those observed from field measurements, considering both mobile and immobile particles.
Highlights
Many regions around the world have experienced an increased frequency of large magnitude flood events arising from changing climate patterns
The role of sediment transport in river dynamics is essential to evaluating the impacts of large magnitude events
There is a dearth of in-situ sediment transport data available for rivers around the world with even fewer studies obtaining observations during large magnitude events to authenticate the accuracy of event-based transport simulations [2]
Summary
Many regions around the world have experienced an increased frequency of large magnitude flood events arising from changing climate patterns. The role of sediment transport in river dynamics is essential to evaluating the impacts of large magnitude events. The severity of an event is often the combined result of the flood wave and the ensuing sediment transport, on the rising limb of the hydrograph [1]. There is a dearth of in-situ sediment transport data available for rivers around the world with even fewer studies obtaining observations during large magnitude events to authenticate the accuracy of event-based transport simulations [2]. The objective of this paper is to develop representative sediment transport models of a river reach where intensive in-situ event based and inter-event sediment transport investigations have been conducted (including a large magnitude storm event) and compare the results to pre- and post-event observations. Mean travel distances of bed material will be calculated using the volumetric rate expression of bed material transport and compared to bed material particle tracking measurements obtained before and after each event [3]
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