The best ideas in environmental management are often the simplest. That sometimes means that they are not particularly photogenic. I offer this as an excuse for the photograph above, in which six ecologists appear to be somewhat underwhelmed by a shallow manmade depression just on the edge of a housing estate near Jarrow. The main topic of conversation, I have to admit, was: “why do they insist on us wearing hard hats when all we are doing is standing in a shallow depression?” That’s health and safety for you.
The visit came as part of a seminar on Sustainable Drainage Systems (SuDS) at Northumbria University which I attended last week in order to brush up some lecture notes ready for the new academic year. I wrote a post last year about how quickly river levels can change in urban areas (see “Fieldwork in the rain”) and the effects can sometimes be catastrophic (the infamous “Toon Monsoon” in June 2012 being a case in point). The problem stems from the lack of permeable ground in urban areas, which means that water runs straight into drains and into rivers.
We could address problems of urban flooding by building bigger and more efficient drains and sewers but that comes at a huge price – both in financial costs and in the disruption caused as roads are dug up to allow access to the drains. Or we could try to mimic nature and simply slow down the journey that rainwater takes once it hits a surface. That’s the basic principle behind SuDS, achieved by providing a range of permeable surfaces, channels and collection / retention ponds, all of which can, at the same time, have aesthetic and biodiversity benefits for local communities. The photograph above doesn’t really capture the aesthetic benefits but my camera was on the wrong setting when we visited a nice reed-lined pond as part of the same development. Sorry.
The works we were visiting were part of a scheme funded by Northumbrian Water to address flooding issues around the Fellgate estate in Tyne and Wear. That a major utility company is investing in SuDS shows how seriously these are being taken as options for flood control whilst, at the same time, illustrating a more profound point. There is a tendency for us to externalise problems such as flooding and to expect local authorities and water companies to find solutions on our behalf. Yet the problem is partly one of our own making. I can look out of my windows and see front and back gardens of neighbours that have been paved over, much reducing the amount of permeable surface into which rainwater can percolate. Your lawn is a part of your local SuDS, whether or not you realised it. And your gutters do not need to funnel straight into the drains either: that water could be collected and used to water the garden or wash the car.
The two pictures below show the direction we could be following: the first is a “green roof” atop one of Durham’s colleges, which uses rain that would otherwise go straight into a water course to sustain vegetation that, in turn, provides insulation for the building below. The lower image shows a “green wall” at a local branch of Marks and Spencer, fed by rainwater harvested from the roof and providing an aesthetic diversion for Newcastle shoppers, as well as playing a role in flood prevention. I also wrote about a flood channel that doubled as an urban recreation space in the centre of Seoul (see “A brief diversion to South Korea”).
Top picture: the green roof of Josephine Butler College, University of Durham; bottom picture: the green wall at Marks & Spencer, Northumberland Street, Newcastle.
One of the vaguer promises of those involved with SuDS is improvements in water quality. I am sure that these will accrue but have not seen the hard evidence to demonstrate this. The problem that I mentioned in my post from last year is that our old “combined sewers” can overflow during floods and dump raw, untreated sewage directly into rivers. In theory, SuDS should reduce the peaks in hydrographs during floods and, in the process, reduce the incidences when the storm sewers overflow. In a river such as the Ouseburn, this could make a real difference to the ecology. But that’s a story for another day…