Urban canals across Britain and Ireland could help protect people from extreme heat by cooling their immediate surroundings during heatwaves, according to a recent study by The University of Manchester.
The research found that canals reduced surrounding daytime temperatures by an average of around 0.8 degrees Celsius. During heatwaves, the cooling effect increased to between 1.5 degrees Celsius and 2.3 degrees Celsius.
The study covered the urban canal network of Britain and Ireland.
Using a new energy balance model developed by researchers in the university’s geography, planning and engineering departments, the study simulated the thermal effects of more than 2,300 canal sections across Britain and Ireland over an entire year.
The researchers found that canals produced a slight warming effect overnight because water retained heat longer than surrounding surfaces. However, this effect was relatively minor compared with their daytime cooling benefits.
The modeling showed that incorporating the cooling effect of canals reduced the number of hours classified as posing moderate heat risk by around 58 percent, while hours of high heat risk fell by around 74 percent.
In many locations, canals eliminated periods of extreme heat risk altogether, although the researchers cautioned that the benefit was partly counterbalanced by rising humidity, which also affected people’s comfort during hot weather.
Around 6.2 million people live within one kilometer of Britain’s urban canal network, meaning that millions could potentially benefit from the cooling effects, according to the study.
Lead author Dr. Matt Tomkins said that as climate change made heatwaves more frequent and intense, “cities need every available tool to help people stay safe and comfortable”.
Tomkins said canals, originally built to power the Industrial Revolution, could now help cities adapt to climate change. Although their cooling effect was modest on an average day, it became much more significant during heatwaves, he added.
The researchers stressed that canals were not a complete solution to rising urban temperatures, but should form part of a wider package of climate adaptation measures alongside parks, trees, sustainable drainage and other green and blue infrastructure.