Liquid assets, Robert Huxford
River Skerne, Durham – an early example of river restoration to create meanders and backwaters
River Quaggy Lewisham, early 1990s, with a concrete channel inhospitable to any life forms
A wetland and flood retention scheme created from mowed grass fields
Liquid assets
UDG Director Robert Huxford reflects on the creativity offered by water
In the pre-industrial city, water was both a limiting and an enabling factor. Before the arrival of motive power, water provided a means of transport second to none. Progress on largely unmade roads was slow, and tonnage limited; by ox a speed of 2mph might be managed, or 4 mph for horse-drawn wagons. Rivers, estuaries and the open sea provided expressways, and tides brought a double benefit, as the rise and fall of the tide allowed boats to settle on their berths enabling them to be scrubbed clean of barnacles and marine growth. This was hugely important for maintaining the speed of vessels. The ebb and flow of tides is also the nautical equivalent of a travellator. In London, skilled lightermen were able to steer a loaded boat 40 miles in 6 hours, and so it is small wonder that many cities are at the heads of estuaries. Nor is it surprising that the roads within settlements should be ordered by the river, running parallel and perpendicular to the foreshore, reflecting the importance of the water frontage as a trading zone.
If the physical carrying capacity of a river was a key factor in the growth of a city, the environmental carrying capacity was surely a constraint. A supply of clean, disease-free water and waste disposal was critical to public health. Ironically the water closet exacerbated the problems of water-borne disease by speeding the flow of excrement into watercourses and water supplies.
Time for change
The nineteenth century brought sanitary science; a Liverpudlian male could expect to live to be 26 years old, compared with 50-60 years for children born in market towns. The impact on the economy or the cost of a sick and ailing workforce was not lost upon industrialists and politicians alike. Huge investments in sanitation followed eventually, with a legacy of ornate water treatment works and interred watercourses. The tragedy is that waterborne disease even in 2008 kills tens of millions people unnecessarily.
But other factors degraded watercourses - the expansion of cities had an impact on drainage, with the conversion of fields and woodlands to roof and roads, and this process has continued in hard-surfaced front gardens to provide car parking spaces. Growing cities also bring pressure for more intensive cultivation and drainage that is so efficient that it increases flows and flooding after heavy rain. For wildlife this is a disaster, with insufficient depths of water to sustain life in the summer to being physically washed out.
The conventional response to flooding was a combination of widening, deepening, straightening and raising embankments, but these also bring consequences. Straightening, for example produces a steeper gradient, with faster and more powerful flows changing the equilibrium of a river. As increased flows brought flood-risks downstream and erosion, concrete channels and culverts were used to manage the problem.
From the 1980s there has been a growing enthusiasm for watercourse restoration following major improvements in waste water treatment and water quality. There was also considerable interest in regeneration and a realisation that water frontage could bring high returns; at the same time, there is also greater understanding of hydrology and geo-fluvial morphology. Since then there has been a steady growth in the number of river restoration projects, and developments making positive use of water and river frontages.
Restoration and appeal
An early restoration project is the Rivers Ravensbourne and Quaggy in south east London. There was once a line of mills along the Quaggy and Ravensbourne running to Deptford – in Samuel Pepys’ time it would have been an idyllic spot. By the late twentieth century the rivers had been reduced to concrete channels, the product of increased run-off, and a mindset that addressed flooding where it occurred, rather than asking why.
But why does a water frontage attract a 20 per cent uplift in value? One explanation is that humans are attracted to the environment in which they evolved – well-watered forest margins.
Other benefits claimed are that human concentration can be restored by entering an environment of natural fascination, away from the place of work. It is hard to imagine a meditative environment without water; for example fountains or pools in cloisters, courtyard gardens, the Alhambra, the Taj Mahal, and in the atria of corporate headquarters throughout the world. There is also stress reduction, with the brain processing sight in different and parallel ways, both conscious and unconscious, differentiating for perception as opposed to action. Therefore these issues run deep, and while no one would recreate a habitat for wildlife without understanding their needs first, we routinely create habitats for people without asking similar questions. Environmental psychology is ‘off-the-radar’ for most built environment people, not least drainage engineers. But perhaps it is an area that we should be more seriously?
Design principles
In order to make use of this knowledge, we should ensure that new and existing developments have minimal impact on catchments, no increase in run-off and no pollution entering watercourses. Sustainable drainage systems should be used with permeable surfaces, swales and retention ponds, resisting the hard-surfacing of front gardens. Retrofitting sustainable drainage in existing developments is going to be a challenge, but it is a choice between this or flooding.
Secondly, we should restore watercourses to their natural state, aiming for an unbroken habitat in and next to the watercourse, from the lowest reaches to its source, including any urban areas. This means providing a natural floodplain; room for the river to erode its banks to form meanders; a natural river bed formed of gravel with sequences of pools and riffles; and, a natural profile. We should also use redevelopment as an opportunity to uncover buried watercourses.
Thirdly we should use water positively, with developments facing water, not backing on to it or built over it. Access should be provided so that people can walk or cycle beside the river. River corridors can provide the spine of sustainable transport systems, and too many river frontages have been destroyed by parallel road corridors destroying the peace and natural beauty of the river. Access to the water’s edge should be provided; natural rivers are inherently safer than channelled watercourses as there is little to fall down or be trapped in, and the flows are less violent.
Urban parks should be used to provide multiple habitats and uses. The case study of Sutcliffe Park on the higher reaches of the Quaggy has created a landscaped flood storage and wetland area, bringing an increase in visitor numbers by 73 per cent, providing important social benefits for exercising and socialising.
The pace of river restoration is still slow, and too many developments are squandering the opportunity to work imaginatively with water. But this will change as more people realise the great benefits: environmental, social, spiritual, and financial, that come from making the most of watercourses.
Robert Huxford
