South East Rivers Trust (& the Wandle Trust)

Teise Habitat Restoration

Since we removed three redundant weirs from a 1.5 km stretch of the Lesser Teise in 2016, the river has been doing a great job at repairing itself and turning back into a functioning system. With water levels upstream of the former weir sites now returned to a more natural state, the pool and riffle sequence is developing nicely with a number of bank slumps and newly exposed gravel berms helping to narrow the channel to a more suitable width.   

During a site visit in October 2018, although we were very impressed with the recovery, we did notice that there was a clear lack of woody material and associated habitats. So to celebrate the second anniversary of the weir removals, we decided to give the ecosystem another kick start by introducing a number of woody deflectors and channel narrowing berms along a 550 m section of the same site.

Woody material entering rivers is a naturally occurring process which is normally initiated by trees falling in off the banks. However due to the low numbers of bankside trees along this stretch, we needed to bring some material in from some other local sites.

We were able to team up with three other environmental improvement projects in the local area which were generating a range of woody material as part of their environmental management plans.

Scotney Castle SSI, National Trust – large trunks and tree tops – as part of pond restoration project

A local contractor was used to transport the wood to the project site using a forwarder tractor and trailer which allowed us to unload it straight onto the bank. Our excavator operator then lifted the brash and woody deflectors into position so we could secure them.

Lifting wood into the river

Over a very cold week back in November in total we installed 15 habitat structures that will help the river to create a diverse range of habitats. These included:

  • 5 x channel narrowing berms
  • 6 x large wood deflectors
  • 2 x hinged bankside trees
  • 2 x coarse wood berms
Hinging the willow into place

A follow up site visit in late March 2019 has shown that all the channel narrowing berms have already filled up with silt to create new marginal habitat and reduce the sharp transition from aquatic to terrestrial habitat. Some of these were installed on existing riffles which will speed up the flow and keep the gravels free of silt.

The large deflectors have begun to scour out the gravels and have created some deeper pools which provide cover for adult fish. The clean gravels deposited into riffles downstream now look like prime spawning sites to be used over the coming months for fish like chub and dace.

Channel narrowing berm along a riffle

The two hinged trees are developing buds which shows they are still growing happily. This will ensure they will provide lovely low cover for years to come.

March 2019 – Deflector paired with live ‘hinged’ tree.

The coarse woody berms have partially filled up with silt to create important features that will provide perfect cover for this year’s juvenile fish fry – warm, shallow conditions with cover.

March 2019 – Alder tree tops creating coarse woody berm.

It will be interesting to see how these structures develop and naturalise over the summer.

Many thanks to our very supportive landowner Robert Day, Peter Prince – Foal Hurst Wood, Mark Musgrave – Scotney Castle, Mark Herbert – Combwell Woods and Tom Barr – BARRK forestry management.

Have any Question or Comment?

3 comments on “Teise Habitat Restoration

Simon Jeffreys

Brilliant. The Upper Medway around Ashurst could do with your attention, and the old mill weir at Ashurst is the key place to start. That will however probably lower the water level by 4 or 5 feet judging by the fall at the weir and BDAS would probably not appreciate their prime weirpool asset disappearing. But it would help restore the river and perhaps help halt the massive sediment movement when the river fills to the height of its banks as it often does after heavy rain.

Simon Jeffreys
Langton Green, Tunbridge Wells

David Lambert

I thought work to prevent future Teise flooding had involved the removal of anything reducing its flow. Won’t the creation of woody berms make flooding more likely?

Jess Mead

Hi David,
The Environment Agency (EA) did previously remove a lot of fallen trees etc. but it’s now widely accepted that they provide important habitat and fish refuge as well as helping to promote natural river processes. The EA now only remove woody debris that definitely poses a flood risk and they leave other material in the river to provide the benefits I mentioned. The berms we installed for this project are low lying an designed to be come inundated under high flow conditions so that they don’t significantly reduce channel capacity. For all work similar to this we apply for (and are granted) a Flood Risk Activity Permit from the EA which requires us to prove that the work doesn’t negatively increase flood risk. So don’t worry, we just get the benefits of re-naturalising the river without increasing the likelihood of flooding. Thanks, Jess.

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