Water scarcity, extreme temperatures, urban heat islands and inadequate infrastructure threaten the viability of many of the world’s arid cities, according to a new report that argues how we design these places needs a major rethink.
Currently 30 per cent of the world’s land surface is classified as arid, with the figure expected to increase as the effects of climate change are felt.
The new report by Arup, Rethinking Cities in Arid Environments, says these cities continue to be developed based on an outdated and inappropriate model established during the middle of last century.
“Cities in arid regions are expected to experience the highest rates of natural population growth and urbanisation in the coming century,” Arup Middle East urbanism leader Hrvoje Cindric? said.
“Yet most are still being planned and designed based on a global city-making paradigm from the 1950s.
“This one-size-fits-all approach, characterised by private car ownership and separate land uses connected by highway networks, fails to respond to specific climatic contexts and needs.”
The report says the current approach to city-making, combined with the effects of climate change, constitutes a “crisis that needs addressing”.
The report calls for “climate appropriate design solutions” to be implemented in these cities to ensure their sustainability and, ultimately, survival.
“A rethink of arid city components, from entire neighbourhoods to individual buildings, squares and streets, will require new planning strategies, design approaches and changes to individuals’ behaviours and attitudes,” it says.
Forty best-practice actions are separated into those for cities, public spaces and buildings, and include:
- Cities: preventing urban sprawl, changing attitudes to recycled water, decentralised infrastructure
- Public spaces: designing for walkability, permeable pavements, productive landscapes, nocturnal lighting
- Buildings: responsive facades, creating microclimates, greening buildings, indoor-outdoor spaces and innovative cooling solutions
Mr Cindric? said thoughtful strategies could help to improve liveability and quality of life for arid city residents.
“Even simple things such as building orientation and the resulting shade can have a significant impact – allowing people to socialise outdoors, rather than rushing from car to building,” he said.
“Rethinking the way we design public space can have a significant impact on the wellbeing of citizens.”
Some leading initiatives used as case studies in the report include:
- Dew and fog harvesting: new technology is allowing for large amounts of water to be harvested even in environments with low humidity levels, for example the Sustainability Pavilion being developed for the Dubai Expo 2020, which will use hybrid structures that generate solar energy and capture water from humidity in the air to supply water to the venue.
- Energy-efficient buildings: the Al Bahar Towers in Abu Dhabi has a dynamic shading system that opens and closes as the sun moves across the building, reducing solar heat gain by 20 per cent.
- Using recycled water for greening: The Recycled Water System of Antofagasta, Chip (SARA in Spanish) is a system that recovers, treats and reuses wastewater for irrigation of public green spaces.
- Cool pavements: Los Angeles has begun coating its streets with a special paint, CoolSeal, to reduce the temperature of the city, which has been shown to reduce ambient temperatures by 6.6°C in testing.
- Green landscapes: Xeriscaping, which is a landscape design approach that minimises irrigation and water use, fertiliser and pesticides, can help to create functional areas with a microclimate suitable for people to use throughout the year.
C40 Cities executive director Mark Watts said the report was and “important step towards understanding the resilience of cities facing water scarcity”.
“It underlines the importance of considering the unique social, economic, environmental and political characteristics of each city to identify tailored solutions for cities in an arid environment.”