John McDonald

Date of Award


Degree Type


Degree Name

Master of Science




Dr. Peter Ashmore


Current studies of urban channel form attempt to understand channel response to major changes in prevailing controlling conditions, mainly discharge. But very few studies actually track channel adjustment over the course of urbanization, ignoring the complexity of channel adjustment to other factors such as large floods and/or engineering. Seldom have these changes been analyzed in terms of expected adjustment from regime theory and the actual processes o f adjustment. Highland Creek in Toronto, Ontario has undergone a rapid transformation from mainly rural to almost completely urban land-use (85% of the drainage area) from 1954 to 2005. It has had a pronounced hydrological response with peak flows reaching up to nine times the pre-urban maximum. Channel form was measured from a series of 5 sets of air photos (1954, 1965, 1978, 2002, and 2005) encompassing the entire development period. The results of this analysis in general indicate that the Creek has become wider and sinuosity has decreased, but variability exists temporally and spatially. Comparison with predicted channel widths using regime theory shows that much of the channel length has ‘under-adjusted’ compared to expectations. It is apparent that this resulted from extensive channel engineering, preventing channel adjustment.



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