Richmond Park restoration: update two years on

It has now been two years since the river restoration work on the Beverley Brook through Richmond Park was completed. This time has allowed the two restored stretches with a cumulative length of 600 metres to adjust and naturalise in response to the changes which were made. The original blogs describing the works can be read in the links below.

http://www.southeastriverstrust.org/delivery-to-the-beverley-brook-in-richmond-park-phase-1/

http://www.southeastriverstrust.org/tree-planting-in-richmond-park/

http://www.southeastriverstrust.org/planting-on-the-beverley-brook/

A key principle behind the restoration was to reinstate natural processes back to the river by providing energy and diversity which in turn would allow it to ‘self-heal’. The river now has the opportunity to scour and erode the bed which consequently creates in-channel features such as pools, riffles and bars which were almost completely lacking before. The uniform sandy bed has been displaced to expose the rich gravels below, providing much improved conditions for invertebrates and fish spawning.

The bed now undulates ranging from ankle deep riffles to waist deep pools. There is now a huge array of flow types and with it a myriad of habitats. For the first time in decades the Beverley Brook is audible as the flows pass over, under and through the Large Woody Material and as it babbles over the riffles.

Large Woody Material narrowing the channel and kicking the flow around

With all this scour and erosion, sediment is being deposited in areas of slack water, such as on the inside of meanders and among the vast quantities of brash that was installed. This is working to such great effect that the brash in many locations is no longer perceivably brash. So much sediment and seeds have been deposited that these now appear to be natural banks which stabilise and help to narrow the channel to the dimensions that the Brook should naturally have. In turn, the vegetation that is establishing collects more silt, and so the channel continues to evolve and diversify.

A brash- berm on the left naturalising with a diverse mix of marginal plant species

The regraded banks and low lying berms are vegetating now that the erected fence keeps the deer and their intensive grazing habits out. Marginal and terrestrial plants are starting to thrive, providing previously absent habitats. The grass really is greener on the other side of the fence.

Follow up macrophyte, invertebrate and fish surveys will take place next summer. By then these communities will have had time to adjust enabling us to make an informed and scientific assessment of the biological impacts of the work. Until we get the results back, anecdotally we have observed significant changes. As previously described, the plant communities are noticeably diverse and extensive. Fish which were previously almost completely absent from the downstream stretch are now abundant with large shoals of dace, chub and stone loach being very apparent.

A picture describes a thousand words so I will keep the blog to a succinct length (for me anyway) with a selection of before and after shots to demonstrate the points raised above. We will keep you posted when we get the results of the follow up surveys.

Before; over-wide, straight, sandy bed and bland with few marginal plants…

and after two years later!!!

Before

Two years on.

Before

Two years on

Before

Two years on

 

A sandy bottom and over-wide channel

Two years on, gravel with marginal plants

An attractive functioning river returns to Richmond Park

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