South East Rivers Trust

Rustling up some Riffles


Our Project Officer Rosie has been out on the River Teise undertaking her first weir removal.

Why was this weir an issue?

Harpers Weir formed an impassable barrier to fish passage on the Teise, a tributary of the River Medway in Kent.

Harpers Weir

Weirs such as this impede the movement of fish upstream and downstream, preventing access to other habitats required for a healthy lifecycle.

They also impound the river upstream, slowing the flow of water and resulting in the deposition of silt on the channel bed. In the case of Harpers Weir, this impoundment was observed for several hundred metres upstream.

Impoundment

For all these reasons, we’ve been very keen to remove the weir and restore fish passage to this section.

In 2015, Rosie started the process by removing the wooden boards on top of the weir, reducing the height to see how the river would respond. You can read this blog here, but in summary it was looking good!

Then, in February this year, Rosie and our contractors Amenity Water Management arrived on site to start the full weir removal.

The concrete weir and flanks were broken up using a hydraulic breaker attachment, before being removed with an excavator. The concrete underneath the footbridge immediately upstream was also removed to let the river bed naturally re-grade back upstream (the footings would otherwise create a new barrier after weir removal).

Diggers on Site

Once the weir and bridge footings were removed, the banks where the weir once stood were regraded, using the excavator with a bucket attachment.  The toe of the banks was stabilised using coir geotextile to line the banks secured with wooden pegs, which in turn were held in place with faggots and pinned with untreated chestnut posts secured with high tensile fencing wire.

After Weir Removal

Once this weir was removed, the upstream impoundment disappeared, and a total of 16 new riffles emerged, with pools between them – all great habitat for many species of bugs, fish and water birds!

You can watch the whole project in our time-lapse footage below!

This project was funded through Defra’s Catchment Partnership Action Fund awarded to the Medway Catchment Partnership, focusing on the River Teise within the Medway Management Catchment.

Have any Question or Comment?

One comment on “Rustling up some Riffles

It would be great to see an update of how this looks several years after the weir was removed and the bank stabilisation installed.

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