A river is reborn …

I started to tell the story of the Ouseburn in the previous post, but have not yet reached a happy ending.  The Beast that is Newcastle Airport has been transformed, if not by a kiss, then by intelligent regulation, but the river is still far from being beautiful.   The Environment Agency, the Handsome Prince in this particular fairy story (has it ever been described in such terms before?) needs to ride out to find other monsters to slay.

One candidate that my students usually identify in their write-ups is phosphorus, whose concentrations have gradually crept up over the years, as the graph below illustrates.   As in the graphs in my previous posts, I have differentiated between data collected by the Environment Agency and my students.  I have also circled a cluster of points that sit outside the main trend, as a reminder that my students are still learning their craft, and sometimes may make mistakes.   The trend is, nonetheless apparent: the river has had elevated phosphorus concentrations for as long as measurements have been taken, and concentrations are gradually creeping upwards.  The student’s data may exaggerate this slightly, but the trend is definitely there.    Although no sewage works discharge to the stream, there are plenty of storm drains, and there are concerns that domestic “grey water”, and its associated detergent residues, may be entering these rather than the foul sewers.  More recently, a study as part of the Ouseburn River Restoration Project (ORRP) has found that some farmers in the upper part of the catchment are stockpiling farmyard manure on behalf of livery stables and some of the leachate from this may be entering the upper stretches of the river.

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Trends in concentrations of reactive phosphorus in the Ouseburn over time.  Woolsington is upstream of the airport, Airport tributary (Abbotswood Burn) receives runoff from Newcastle Airport and Jesmond Dene is about 10 km downstream from the airport.  Closed symbols are annual means of data collected by the National Rivers Authority and Environment Agency; open symbols are means of data collected and analysed by Newcastle University Geography students in October (once also in February) of each yearThe lower dashed line is the UK environmental standard for reactive phosphorus to support “good ecological status”; the upper dashed line is the threshold between “moderate” and “poor” status (the threshold between “poor” and “bad” status is at 1.04 mg/L).

In addition to problems such as phosphorus that we can see from our analyses, there are problems that are less obvious because they only happen occasionally, and not necessarily when a sampler is dipping a bottle into the river.  The Pantomime Villain of this story (“He’s behind you …” “oh no he’s not”, “oh yes he is …”) is the overloaded sewerage network and, in particular, the storm sewer overflows which divert foul waste into the river when the sewers are overloaded with surface water from heavy rain.   Even though the graphs in the previous post showed that ammonia and BOD are usually at low levels, there will be short periods when the storm sewers dump raw sewage into the river.  This is a great lesson to my students in why biological monitoring is so necessary: the poor quality of the invertebrate community reflects the state of the river through the whole year, not just the minute or so when the sampler’s bottle is being filled.

A combination of hard impermeable surfaces, the drainage system with its overflows and many artificially-straightened lengths of the river mean that storm water makes its way very quickly to the stream (see “Fieldwork in the rain”).  In extreme cases this can lead to homes and businesses being flooded.   These straightened sections of the river also mean that there is little variation in velocity to create the variation in habitat that would allow a range of organisms to find suitable conditions to thrive.   So another of the objectives of the ORRP is to restore the natural meandering path of the river in the upper stretches as a first step towards creating a more natural river which will, at the same time, slow the flow and reduce the likelihood of flooding downstream.   New property developments such as Newcastle Great Park have been designed with Sustainable Drainage Systems (see “In search of SuDS …”) to create more permeable areas that will soak up rainfall and slow its journey to the river, reducing the size of the flood peaks associated with heavy rainfall.

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Challenges facing the Ouseburn: left: Newcastle Great Park, one of a number of new or planned housing developments in the upper part of the catchment; right: straightened river channel near Three Mile Bridge beside the Great North Road in Newcastle.

To be honest, there are many grander rivers in the country than the Ouseburn where I would prefer to do my fieldwork.  I feel privileged to be able to visit the River Ehen in the Lake District on a regular basis.   We rightly worry about maintaining fragile ecosystems and rare species in these remote places but the Ouseburn presents equal, if less romantic, challenges.   Most of us are urban, rather than rural dwellers and our most likely interactions with the aquatic world will be with these artificially-straightened extensions to our overloaded sewerage systems.   There is something of Frankenstein’s monster about these rivers: at their worst, in flood, they are our own creations, the result of our own attempts to overrule nature.  So I am very enthusiastic about the work of the ORRP and similar schemes around the country.   These are a small step towards restoring a natural harmony between man and water, and working with, rather than against the powers of nature.  And creating a greener, more pleasant urban milieu in the process.

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In search of SuDS …

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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”).

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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…