Land Use and River Systems: Impacts of Suburban Residential Development on Channel Stability and Water Supply, Oak Ridges Moraine, Southern Ontario

To better understand the impacts of suburbanization on rivers and with the sensitivity of the Oak Ridges Moraine in mind, this study examined the geomorphology and hydrology of streams running through small, primarily residential developments in the Humber River headwaters. Local scale impacts were analyzed by comparing paired upstream reference reaches to reaches downstream of developments in Caledon East, Palgrave, and Bolton. Channel morphology was assessed via bank soil strength measurements, vegetation cover, quantification of large woody debris, and visual assessment, allowing for inferences about potential downstream bank degradation symptomatic of streams in urban areas. Hydrology was evaluated using continuously measured water level and empirically estimated discharge, comparing hydrograph features between paired sites. Caledon East exhibited changes in morphology and hydrology symptomatic of the urban stream syndrome. Similar changes were seen at Bolton, but anomalously lower flows downstream confounded results. Palgrave did not exhibit impacts characteristic of urbanized streams.