Studies of fluvial sediment transport, sedimentation and river morphology

点击翻译按钮获取中文摘要

The objective of the program is to understand the factors governing the development of alluvial river channels (i.e., channels self-formed in their own sediment deposits), amongst which sediment transport is paramount. Four styles of work provide complementary results and allow students freedom to select their style of work: (i) flume experiments on sediment transport and sedimentation; (ii) field measurements of sediment transport and channel geometry; (iii) long-term studies of channel response to sediment transport; and (iv) theory about river and landscape evolution. We have initiated experiments on grain sorting in bedload transport (in cooperation with the French institute IRSTEA) and on Shields’ entrainment criterion for sediment. The former entails a novel view of sediment transport as a granular phenomenon. The latter is the foundation for sediment transport theory but has remained unchallenged for 80 years. We consider the Shields number to be a bed-state parameter, not simply a grain mobility number, which entails investigating the effect of structural arrangements of sediment on the stream bed, not considered by Shields.We continue to study the response of Peace River to flow regulation in the 1960s for hydropower production, in particular to apply our developed rational regime theory to predict the new equilibrium form toward which the channel is evolving. We will also extend our field record of channel adjustment, which is now more than 40 years long, by resurveying our monumented cross sections in 2014. We will continue to study the problems of gravel influx and channel bed aggradation in lower Fraser River, which appears to be a legacy of 19th century placer mining. In particular, we are investigating the effect of cover sand transport on the estimated overall sediment budget. We have also initiated studies of suspended sediment transport in Fraser River at Mission, BC, using novel acoustic techniques and of sand transport in the distal estuarine channel. We will continue critical studies of sediment transport modelling over extended periods and distances using data from Fraser and Chilliwack rivers. The Fraser study represents an attempt to further substantiate the placer mining legacy. The Chilliwack study seeks to expand methods for physical analysis of land management outcomes beyond the scale of small drainage basins, to which it has mainly been limited. These studies are also a contribution toward understanding landscape evolution in the intermediate term between time scales of contemporary process and those of tectonic evolution, and over intermediate landscape areas (order thousands of square kilometres), important scales that have largely been neglected.Much of this work, especially on Peace and Fraser rivers, has immediate significance for river management, in the former case in relation to projected further hydropower development and in the latter in relation to flood protection. Indeed, some of the science is motivated by practical questions we have been asked to resolve in relation to these issues.