Author(s): N. S. Weber; D. C. Arseneau; J. Parish; B. Kilgour; R. Snodgrass
Linked Author(s): John Parish
Keywords: No Keywords
Abstract: Many municipalities in Ontario, Canada are acknowledging the value of natural streams in maintaining water quality and ecosystem health within the urban environment. Urban stream rehabilitation projects often convert concrete lined and/or straightened channels to a more natural condition. Natural channel design practices exist to guide hydraulic engineers in establishing channel physical characteristics. However, few design tools exist to aid practitioners in evaluating design alternatives in their ability to provide physical habitat to local fish species. The City of Toronto is undertaking a class environmental assessment (EA) for the rehabilitation of an urban stream. As part of this effort they are exploring the utility of habitat modeling in assessing design alternatives. Three models have been chosen: a landscape-based regression model, an Ontario-specific habitat-suitability model based on habitat data collected using a point-transect methodology (i.e., Ontario Stream Assessment Protocol (OSAP)), and the USGS Physical Habitat Simulation Model (PHABSIM). This paper outlines the methodology and results from the initial trial of the PHABSIM component of the program. PHABSIM combines hydraulic simulation with habitat suitability indices (HSI) to establish the level of habitat available. In this study, a typical, straightened urban stream reach with limited meander width and gabion lined banks was defined as the pre-rehabilitation case. A natural meandering channel and a spot rehabilitation that might be the outcome of a rehabilitation EA process were identified. Each alternative was evaluated against the HSIs of several Southern Ontario fish species to evaluate the designs. The results show that this technique can be used to screen design alternatives with respect to physical habitat quantity and quality and guide rehabilitation design.
Year: 2009