Thursday, 10 July 2014

Life Aquatic

Greetings!  And a long time it has been; I have been off-blog for a good few weeks due to events such as holidays, moving house and the hectic workload that June bought us.  Weeks of warm breezes and sunlit hours also ensured that our working time was spent on outdoor jobs, leaving the office stuff for a rainy day – a plan that never works well in winter but comes into its own in summer.

The summer solstice has been and gone already, and it is almost inconceivable to me that we are halfway through the year and heading back into the shorter days of winter - however, I won’t dwell on that for now as we are still enjoying the heat in which to get our work done.  And with the onset of June came, of course, the first of the three annual weed cuts on our river stretches.  Our river keeper Neil dove (haha) back into action and spent every waking minute for 2 weeks in the river trimming the Ranunculus whilst obtaining a small population of ticks on his various body parts as he went – he is one of those useful people to have around as he draws ticks towards him before anybody else.  I did my part where I could and helped him push on the weed down the River Dun which, in the hot weather was a delightful task, even when we had to start over again due to more weed coming down from the upper stretches.
Salute of the weed Cutters

The weed cut period has also allowed me to begin a project that has been years in coming and will be ongoing for years more.
Stockbridge Common Marsh is a site of ours that lies in the village of Stockbridge, just down the hill from Stockbridge Down.  It is a 23 hectare site alongside which runs a tributary of the River Test, called Marsh Court River.  Now this site has some valuable fen and marsh habitat as well as important chalk stream habitat, both of which serve to class the marsh itself as a Site of Special Scientific Interest, and the river tributary as a separate SSSI.  Consequently these designations as well as the beauty and tranquillity of the habitat for both humans and wildlife alike, mean we have to do our best to protect and preserve them both.
If you have ever walked on the Marsh you will have noticed the badly eroded river bank on the Marsh side.  Now any river bank that is made of peat, as this one is, is going to suffer some erosion from natural river processes as it is a soft substance that the current of the river is able to wear away.  However this process is usually buffered by a marginal fringe of bank side vegetation of rushes and reeds, water parsnip and so on, all of which help stabilize and protect the banks and provide brilliant habitat for water voles, damsel and dragonflies and water birds found here.

The bank side of Stockbridge Marsh is almost entirely devoid of vegetation due to river erosion and the pressure of livestock, people and dogs climbing in and out and breaking off the overhanging turf which has suffered river erosion beneath it.  There have been many plans over the years to try and improve this bank and save it as the erosion evidence is plain to see – you can see chunks of bankside turf that have fallen in over the last few months, just lying in the river. 
In order to re-stabilize and allow the bank to regenerate I have worked with Natural England and the Environment Agency to come up with a plan of action.  Consent was then sought from both agencies and gained, and I was finally able to begin the first phase of work during the June weed cut.
We have erected a fence along the first 200M of the river, which contains some of the worst eroded stretches.  This fence will remain in place until the bankside vegetation has grown up enough and the bank has recovered enough to allow it to better stand the pressure that is put upon it.  A fence was erected some years ago along the top part of the river and the vegetation that has grown up there has proven how beneficial it has been in keeping it protected until it has recovered.
The new fence

So the fence went up and then come the weed cut (when the fisheries downstream would not be disturbed by work we would be doing) I started installing a geotextile material, with the help of work experience students and our countryside volunteers.
This geotextile material is essentially an engineered form of faggoting, but one that is more durable than faggots and better for long-term works.  We installed it by post banging down some specially treated stakes that came with the material, designed to be used in rivers.  These were hammered down into the river bed and the geotextile contains ‘pockets’ through which you slide the stake before hammering it so that you can then pull the fabric tight along to the next stake and so on.  You end up with a long edge of geotextile that will basically serve as the new bank side whilst the area behind it begins to grow in.  This was very hard, hot work as we had to do it all manually due to the sensitive nature of the bank – no post banging machine would have been able to be sat on the bank edge as its weight would have collapsed it.  So, waders were dug out from the sheds where they had sat since last year, and we jumped in the river and worked from the waterside.  

The geotextile in place
The geotextile in place


The geotextile was finished in June and now, with the July weed cut looming, we can begin the next step, which is to work on the banks themselves.  The bank will be manually dug out under their overhanging edges; just enough so that the top layer of turf can be folded down to create a shallow slope.  This will slope down into the water behind the geotextile and the remaining area will be filled in using peat dug out from the bank and vegetation transplanted from other areas of the site, to help it begin the regenerative process.  By creating this shallow sloping margin, you are making a far more natural habitat than the current steep sheer sided banks that erosion has created.  Different plants, invertebrates and other wildlife utilise different areas of the bank based on the different gradients and provides far more diversity than the sheer faced eroded bank side.
The stretch that we are working on contains the shallower part of the channel.  There are some parts of the channel that are much deeper and would require the river bed raising before we could do bank works.  However this first step will enable us to gauge the success of the bank work on the shallow channel (and I believe it will look fantastic in a growing season or two) and thus plan our next step.

Obviously this is a very sensitive project as the Marsh is a beautiful and popular place for people to walk their dogs, enjoy a picnic or just come dip their feet on a hot day.  The work we are carrying out has had both supporters and opposition, mainly due to the presence of the fence.  Whilst another 500m or so of the river remain unfenced and therefore perfectly accessible, we appreciate that people may find the fence along the first bit visually disturbing and it may look like we are trying to bar people from being able to enjoy walking by the river.  This is obviously not the case as we do in fact want to try and preserve this stretch of river for the future so that more people can enjoy it, hence the work.  If we did not carry out this bank work, the bank would continue to fall and the river would become wider, deeper, and siltier and lose all the important features and aspects that are so valuable in the ecology and make up of a chalk stream.  

So, many thanks to the Stockbridge Court Leet who have funded the fence and geotextile materials for this work and thanks to those people who stopped to talk to me whilst I was working on the bank work and boosted us with their support – it means a lot when you realise that people know you are trying to do what is right for a habitat in order to preserve it – forever, for everyone, right?

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