Urban water consumption will increase due to climate change, Concordia research shows

The world’s access to water has long been a constant challenge for municipal authorities as mass urbanization, climate change and now the COVID-19 pandemic constantly force cities to adapt to new demands on their networks.

In a recent paper published in Sustainable Cities and Society, three Concordia researchers look at water consumption in one urban community – in this case, the Montreal off-island suburb of Brossard, Quebec – and how that consumption fluctuates seasonally.

Big jumps with high temperatures

The researchers correlated daily water consumption data they obtained from the City of Longueuil, which administers Brossard, with daily air temperature readings from Trudeau International Airport and precipitation records. They benefitted from a large data set, spanning January 2011 to October 2015.

Using Bayesian statistic techniques, they noted that outdoor water consumption was higher when temperatures were higher. They did not see any link between temperature and indoor water consumption (though they did notice an uptick in use on weekends compared to weekdays).

“We found that when air temperature is above a certain value, water consumption goes up,” says Samuel Li, a professor in the Department of Building, Civil and Environmental Engineering at the Gina Cody School of Engineering and Computer Science. Li co-authored the paper with Masters student Niousha Rasi Faghihi and Fariborz Haghighat, professor and Tier 1 Concordia Research Chair in Energy and Environment.

The researchers noted that Brossard’s average water consumption per capita is around 300 litres per day. “But in the summer months, when people are watering their gardens, lawns and flowers, that consumption can increase by as much as 65 per cent.”

Planning 30 years ahead

With the correlation between temperature and water use established, the researchers then asked what urban water consumption would be like around 2050.

“Water infrastructure has a lifespan of about 30 years, after which it needs an upgrade,” says Li. “So what do we expect to see three decades from now?”

That depends on the climate models they use. The researchers looked at 21 different climate models and three possible emissions reduction scenarios: one with no significant changes in emissions, another with some emissions-reduction measures in place and a third with more aggressive measures.

“In all of these cases, we see a trend where temperatures and water consumption go up; it’s just a matter of how much,” says Li.

Li and Haghighat say their study is one of the first to include climate change as a factor in estimating future water consumption in urban areas. Previous studies, they note, focused mostly on population growth.

The current pandemic will add a new dimension to their research into urban water use.

“We need up-to-date information about resulting changes in water consumption by the manufacturing sector as it shuts down and then reopens, the service sector and residential neighbourhoods, where demand likely spiked as thousands of office workers began working from home, in order to develop reliable models for prediction of urban water demand,” they say.

Going forward, they hope to develop a system of smart water meters, most likely a mobile application, which would deliver real-time feedback about water and energy consumption of individual users. The feedback information would be crucial, especially during the hot season when the water distribution network cannot provide the required amounts of water.

The Natural Sciences and Engineering Research Council of Canada (NSERC) provided financial support for this study.

Read the cited paper: Forecast of urban water consumption under the impact of climate change