An Evaluation of the Contributions of Urbanization and Climatic Change to Runoff Characteristics in the Laurel Creek Watershed, Ontario

Abstract

The hydrological consequences of urban growth and expansion of impervious surface area between 1950 and 2000 in the Laurel Creek Watershed, Waterloo, Ontario were investigated. Changes in the hydrological regime were assessed using annual summaries of census, climate (temperature and precipitation), land use and runoff data. Population growth has been linear (+1000% over fifty years) and urban (impervious) area expansion has been even greater over the same time period (about 1200%). The runoff ratio increased significantly over time, but other derived hydrological indices and climate variables did not. This research indicates that there are significant challenges in predicting the hydrological consequences of urban expansion in a changing climate using long-term data sets. Lack of evidence of hydrological impacts using analyses such as these may be a consequence of threshold-dominated watershed behaviour. Changes in land cover, precipitation timing and magnitude and water balance dynamics in the future may diverge from historical patterns, and should be considered by land use planners and others responsible for municipal water issues. © 2004, Taylor & Francis Group, LLC.