CGRG Bibliography of Canadian Geomorphology
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Author : Burge, L.M.; and Desloges, J.R.
Date : 2005.
Title : Channel response to flow regime changes in urbanizing watersheds.
Publication : Annual Meeting of the Canadian Association of Geographer. Tuesday, May 31 to Saturday, to June 4, 2005. University of Western Ontario, London, Ontario.
Issue :
Page(s) :
Abstract
Research into urban channel erosion has concentrated on the effects of the increase in peak flows. Channel shortening and vertical degradation are two major responses that have not been systematically investigated. This paper investigates the relation between changes in peak discharges and channel sinuosity within a highly urbanized watershed of east Toronto. Highland Creek is located in Scarborough in the city of Toronto, has 75 km of stream channels, and has a basin area of 102 km2 that is 85% urbanized. Analysis of discharge data near the outlet of Highland Creek shows maximum mean daily annual discharge increased throughout the study period (1956-1998), however, the largest increase occurred after 1972. Partial duration flood frequency analysis performed on flows occurring before and after 1972 (representing pre and post urbanization) show the 2-year flood increased by almost 100%, from 12 to 23 m3/s. Channels within the lower reaches of Highland creek, mapped from aerial photographs from 1954 and 1999, widened between 3-37%, while channel length decreased from 10.7 to 9.7 km, representing a 12% decrease in sinuosity. The decrease in sinuosity, due to channel avulsions around meander bends and channelization works, increased channel bed slope and the erosive potential of the channels at the same time that peak flows increased. Many reaches of the channel can now be characterized as unstable.
Bibliography of Canadian Geomorphology