Impact of climate change on urban water demand in future decades: an Australian case study

World's climate is changing and it is predicted by a significant number of scientific studies that changes in climate conditions will escalate in the later part of the century. As a consequence, urban water demand is likely to be affected. Changes in water demand will exert significant pressure on the water authorities to maintain the balance between water demand and supply. Therefore, assessment of climate change impacts on water demand is crucial to ensure water demand is met under changed climate conditions. This chapter discusses the outcomes of a critical review of literature on climate variables in water demand modelling. It also evaluated the impacts of climate change on future water demand in the Blue Mountains region, New South Wales, Australia, as a case study with the climate projections from a global climate model, CSIRO Mk. 3. It was found that temperature and rainfall are the mostly used climate variables in water demand modelling; however, their form (e.g. maximum temperature, total rainfall and number of rain days) and incorporation of other climate variables in modelling need to be investigated to develop a robust water demand model to identify the climate change impact more efficiently. Results of climate change impact assessment on urban water demand demonstrated that future water demand in the Blue Mountains region in Australia would not be significantly impacted by the changed climate conditions. The results presented in this chapter provide important insights which could be useful in conducting a more rigorous climate change impact analysis on urban water demand in other cities and regions.