International scientists urge urban planners to stop burying rivers to build cities

Urban planners hold a critical but untapped power to reverse the collapse of freshwater biodiversity, a team of international scientists has warned. 

Rivers, wetlands and ponds cover just 2.3 per cent of the Earth's land surface but support a third of all animal species. In cities - where freshwater has been buried, channelled in concrete, and floodplains built over - ecosystems face the most intense pressure of all. 

Freshwater animal populations have declined by an estimated 84 per cent in recent decades, a greater collapse than that seen in either marine or land environments. 

A new paper, published in the Journal of Environmental Planning and Management, says that the professionals responsible for day-to-day land-use decisions in urban areas hold the key to protect and restore these important habitats. 

Lead author Dr Helen Currie, from the University of Portsmouth's Centre for Blue Governance, said: “Our rivers, ponds and wetlands have been treated as plumbing for decades - nuisances to be controlled rather than living ecosystems to be valued. Urban planners are uniquely placed to help fix this problem, if we give them the knowledge and support to act.” 

Only 37 per cent of the world's longest rivers remain free flowing along their entire length. Global wetland loss is occurring at 1.6 per cent a year - more than three times the rate of forest loss. 

The research team - made up of experts from 16 institutions across the world - identified six actions needed to mobilise urban planners as allies in freshwater conservation. 

These include equipping them to value biodiversity; supporting community involvement; breaking down barriers in planning education; improving knowledge exchange between planners and ecologists; developing enforceable standards and policies; and addressing gaps in practical scientific guidance. 

Co-author Professor Steven Cooke of Carleton University, Canada, said: “The planner working in a local authority has more power to protect freshwater life than most people realise. What's missing is the systemic commitment to train them in freshwater ecology and give them the policy frameworks to act.” 

Cities from Seoul to Vancouver are already showing what is possible. In South Korea, a buried urban stream was restored after a motorway above it was demolished, boosting both biodiversity and community wellbeing. In Vancouver, nature-based stormwater systems have been integrated into urban design alongside indigenous community engagement. 

In England, mandatory Biodiversity Net Gain was introduced two years ago. Under the rules, most new developments must deliver at least a 10 per cent uplift in biodiversity value, including a dedicated water metric for sites within 10 metres of a freshwater body or a riparian zone. 

While a step in the right direction, the authors warn the policy places significant demands on local planning authorities that often lack ecological expertise or resources. 

Co-author Professor Irene Gregory-Eaves from McGill University, Canada, said: “We already know how to build cities differently - there are inspiring examples on every continent. What's missing is the commitment to train planners in freshwater ecology and to give them the policy frameworks to act on it.” 

The study also presents a vision of what a city designed from the ground up with waterways and ecology in mind could look like. Stormwater ponds could be managed as biodiverse wetlands rather than overflow tanks, floodplains reconnected so rivers have room to function, and buried streams 'daylighted' and returned to community life. 

"Housing, roads, parks and industry should be planned in harmony with the freshwater landscape,” explained Dr Currie. “We recommend ecologists and communities are brought in from the outset rather than as afterthoughts. That way they can work collaboratively with planning experts, to ensure our cities and towns are built for all creatures, great and small.”