Thresholds of erosion and sediment movement in bedrock channels: A case study of the Etobicoke Creek, Southern Ontario, Canada.

摘要

This study examined the erosive resistance of the discontinuous, loose joint blocks of various sizes that comprise the bed material of the Etobicoke Creek, an incised bedrock channel found in an urbanized setting within the City of Toronto. In order to accomplish this, both field and laboratory experiments were conducted on the bed material found in this channel.;The field work showed that the distances moved by the rock clasts scaled directly with shear stresses observed during rain events. Few clasts were entrained during these rain events however and those that did, were only transported over short distances. Flume experiments demonstrated that the clasts offered different levels of resistance to movement, depending on their orientation. The results have significant implications for the understanding of bedrock rivers from a management perspective, especially in the case of those rivers experiencing the effects of urban development in their drainage basins.