Modeling Water Demand Considering Impact of Climate Change – a Toronto Case Study

Abstract

Municipal water demand modeling is a complex process that involves human response to climatic and non-climatic conditions. Forecasting of water demand is indispensable for the daily operation of existing water supply systems and the planning of future systems. The prospect of global climate change added a new dimension to the existing uncertainty associated with the forecasting of municipal demand for water. In this chapter an analysis of Toronto's daily water demand is carried out and a methodology for the forecasting of this demand is provided. A model for the prediction of the daily water demand of the city of Toronto is developed. The model provides a tool to optimize the daily operation of the water supply system with the goal of minimizing energy cost and improving water quality. A second model for the long-term forecasting of Toronto's water demand is also presented. The long-term demand model is used to evaluate the impact of climate change on Toronto's future water demand. The study has shown that a 1°C increase in summer maximum daily temperature would result in a 2% increase in average summer demand and 1.8% increase in peak day demand. Toronto's peak day demand of year 2000 would increase by 23% as a result of a 15% increase in population coupled with having a summer in which the maximum daily temperature increase by 5°C and the rainfall decrease by 10%. Planners and engineers need to consider climate change scenarios in the planning strategy of future water supply systems and delivering projects.