After blogging about Sheffield residents – and many in Mumbai – protesting against the felling of urban trees by Amey, better news comes from David Bailey (right). He draws attention to an article by David Cox, about ‘daylighting’ or ‘deculverting’ of urban rivers – the source of much of the following information.
Simon Ogden, chair of the Sheffield Waterways Strategy Group, recalls that the city’s rivers were used originally for water power, then for steelworking and waste disposal and finally built over and turned into sewers, commenting “That’s about as low as a river can get.”
Sheffield rivers, the Porter, Sheaf and Don rivers spend most of their urban life underground. The Porter flows between buildings, in culverts and below the surface in tunnels. It sometimes surfaces on its way to the Ponds area and, as it approaches Sheffield Railway Station (left), joins the River Sheaf under the station.
‘Daylighting’ rivers can be a more practical and cost-effective alternative to many of the UK’s Victorian-era culverts that are difficult to maintain. Last year, in central Sheffield, a culvert over the River Porter collapsed, causing part of a car park to completely cave in.
In a once-neglected corner of Sheffield’s cultural industries quarter, where music, film and science-based businesses flourish, there is now a green oasis – a “pocket park”- among housing blocks and a derelict industrial site A small amphitheatre slopes down to the banks of the river Porter, where wild trout spawn in spring and students from the technical college picnic and paddle.
Two years ago, the park did not exist. There was just a crumbling car park with the River Porter seen briefly before it disappeared into a culvert.
Simon Ogden describes the long-standing ambition of the WSG to reconnect the city centre with its waterways – the canal, Rivers Don Porter and Sheaf.
One proposal – called ‘Putting the Sheaf back into Sheffield’, featured on the BBC’s One Show – involves taking the roof off an underground culvert and bringing the waterway back into the open, surrounded by grass, flowers, trees. The bid for funding from the Heritage Lottery Fund was not successful but ‘pocket’ parks are being created through the council’s’ City Centre Breathing Spaces programme’, using money contributed under planning rules by developers.
Climate change has been one of the major driving factors for large-scale investment in river daylighting projects
Planners hope to utilise the passive cooling provided by rivers to help combat the urban heat island effect, and most of all, increase flood protection. Funding the ‘daylighting’ of the Porter in Matilda Street and Nursery Street has been combined with the Environment Agency Local Levy which aims to cover the cost of flood defences.
“We’ve been experiencing more flash floods in recent years,” says Ogden from Sheffield council. “So we need to keep the water in the river and make more space for it. Culverts act as a kind of choke on the river, so any blockages or sudden increased rainfall forces the water out onto the streets.” He continues:
“A culvert was removed over a stretch of the brook hidden beneath a car park, and riverbed material was redistributed and stabilised using boulders and reclaimed wood. Habitats have been created for fish with help from the Trout in the Town organisation, walls made of gritstone slowly release rainwater into the brook and the park has been designed to flood in extreme weather”.
News of a Rochdale project follows.
Cox’s article also has references to work in Auckland, to Seoul’s artificial waterway that joined up with the underground river at formed 3.6 mile-long water corridor now acts as a major flood-relief channel, transforming an area of Seoul previously renowned for crime and to Zurich, where urban river restoration has been common practice and daylighting – known as the “Bachkonzept” or the “stream concept”, is has been ‘enshrined in law’