Modelling changes in stream water quality due to climate change in a southern ontario watershed

Abstract

This research represents a pilot project to establish a methodology for assessing the sensitivity of watershed stream water quality to changes in water quantity caused by climate change. The pilot watershed is the Duffins Creek watershed, located 20 km east of the City of Toronto, Canada. Scenarios of climate change analyzed in this project were drawn from two internationally recognized climate models: the Canadian Centre for Climate Modelling and Analysis (CCCma) CGCM1 and the Hadley Centre HadCM2. The AGNPS (Agricultural Non-Point Source) model was used to predict changes in stream water chemistry. The results are compared to baseline conditions as well as future conditions based on 2020 land use scenarios. It was determined that 2020 land use scenarios typically result in much smaller changes in peak flows than are predicted for the climate change scenarios, especially the wet climate change scenarios. Understanding climate change responses is critical for the development of watershed plans and drinking water source protection studies. Currently, watershed studies are completed using climate information based on relatively short-term monitoring databases that reflect past weather patterns. It is widely understood that management actions advocated in watershed studies could be improved if consideration were given to the implication of climate changes. © 2005, Taylor & Francis Group, LLC.