(Montreal) Researchers at Concordia University say they have identified an “almost always effective” way to curb urban sprawl, especially in big cities.
Posted at 11:50 a.m.
According to their study, the use of “green belts” on the outskirts of urban centers could limit this phenomenon that is harmful to the environment. These belts are protected areas, such as forests or agricultural land, which surround a city or region and in which real estate development is strongly limited or even prohibited.
According to Parnian Pourtaherian, lead author of the report published in the journal Landscape and Urban Planningthese spaces would prevent the often disorderly expansion of suburbs and economic sectors.
Using open-source data, the researchers tracked the urban sprawl of 60 European cities between 2006 and 2015, half of which had a green belt. These were classified into four categories: very large cities (2.5 million inhabitants or more), large cities (more than one million inhabitants), medium-large cities (500,000 to one million inhabitants) and medium-sized towns (96,000 to 500,000 inhabitants).
According to the study, 90% of cities with a green belt had experienced a decrease in urban sprawl during the given period. Conversely, only 36% of the other cities experienced such a decrease.
“We found great variability in the effectiveness of the green belt in small, medium and large cities, but the difference in the relative changes in urban sprawl was more marked in large cities”, specifies the researcher.
Parnian Pourtaherian, who holds a master’s degree in science in the department of geography, urban planning and environment at Concordia University, argues that this method could also be used across Canada.
“Ottawa and Toronto both have a green belt, and Vancouver has a ‘green zone’, which acts as such. On the other hand, Montreal still does not have a real green belt, but it urgently needs one,” she says.
Efficient… so well regulated
For Jochen Jaeger, professor in the department of geography, urban planning and environment at Concordia University, green belts are almost always effective, provided they are well supervised. Their performance can be undermined if they are not properly protected, underlines the researcher, or if they are too small or too narrow.
“Some developers and politicians are abusing the housing crisis argument to expand large development areas and allow additional low-density urban growth, or even remove existing protective laws. They also apply a ‘salami tactic’ to chip away at the green belt by arguing that every little piece lost is just a ‘meaningless’ loss – until there’s nothing left,” laments the co-signer of the study.
These green belts are a major obstacle to urban sprawl, which consists of an increase in urban areas over a given territory. This phenomenon is characterized by low densification and a large area, often only accessible by road.
This sprawl towards the suburbs may seem to go hand in hand with the growth of the population, but its expansion distances the inhabitants from the services offered in the major centres, in addition to threatening the fauna and flora on the outskirts of the cities.
“Limiting urban sprawl is crucial as it leads to the loss of green spaces and wildlife habitats, as well as reduced ecosystem resilience due to habitat fragmentation, declining wildlife populations and of the extinction of local species”, specifies the Dr Jaeger.
These effects will only be exacerbated by the climate crisis, adds the researcher, leading to higher expenditure on transport infrastructure, electricity, water supply and sewage collection. Urban sprawl is also associated with increased consumption of fossil fuels for transportation as well as the loss of fertile agricultural land.
“Avoiding the expansion of low-density urban areas into natural spaces maintains the benefits of these spaces – including better air and water quality – which the current generation can then pass on. to future generations,” he concludes.