Urban watershed ecological risk assessment using GIS: a case study of the Brunette River watershed in British Columbia, Canada

Urbanization has a dramatic impact on the health of local streams. The complexity of the many stressors, pathways and ecosystem functions at risk presents a serious challenge to traditional scientific and management approaches. To overcome this complexity, this study developed a general framework and specific procedures for a screening level ecological risk assessment for urban watersheds, and applied it to the case of the Brunette River watershed, a small urban watershed of 70 km(2) in the Vancouver area of British Columbia, Canada. A generic conceptual model was developed and a set of key indicators was selected: impervious areas, riparian habitat, pollutant loadings, water quality, sediment quality, fish health and public health. Information on each of the indicators was transformed into a single dimensionless score. Two indicators (impervious areas and water quality) were selected for a more detailed evaluation of spatial and temporal patterns using a Geographic Information System. Results were displayed in hypermedia modules and presented to local watershed professionals and decision-makers as part of the ongoing development of the methodology. The integrated approach, using a limited set of key indicators and GIS maps to visualize complex scientific information, was well received as a decision support tool. (C) 1998 Elsevier Science B.V. AU rights reserved.