South East Rivers Trust (& the Wandle Trust)

Achy arms and elbow grease – Harry’s NFM diary.

Through our ongoing Natural Flood Management project (FRAMES), I’ve recently been working as part of a team in Kent focusing on construction of leaky wooden structures (LWS) – you can learn more about them, and how they work, in Dean’s blog.

One of my favourite sites was Church Wood. A typical day spent here would consist of meeting the team and hopping in the truck of the woodland contractor (either Ben or Dave).

Once down by the “ghyll”, we would decide on a location for the next LWS which would best allow it to temporarily store and slow as much floodwater as possible. After selecting a location and appropriate building material, work would begin!

Leaky Wooden Structure in Church Wood

In the case of the structure in the photo above, we discovered a naturally fallen large oak which looked perfect for the structure we were building. The only slight problem was that it 25m up a steep clay bank, weighed over a tonne and recent rain meant that the area was particularly slippery. This wasn’t a problem however for Ben, our woodland contractor, who had a plan. Ben quickly envisaged the steps needed to move the timber, using a combination of winches and pulleys which would be anchored off nearby trees, allowing us to safely move the wood into position.

Having connected either end of the timber to winches, we began slowly winching the oak down the slope. We would regularly have to change the anchor points to maintain control of the timber and to change the direction in which the timber was being winched.

Miguel preparing the timber for transport using the winch
Combination of winches being used to safely transport the oak
Moving the oak into position – almost there!

You may be wondering why we chose such a large piece of timber! Although this stream appears calm and quiet for most of the time, it is a very “spatey” stream, meaning that it is prone to sudden and intense flooding. A rise of ~1m during a flood is not uncommon here, so where possible we favoured the use of big, robust material which would effectively hold back water and also last for a long time.

Finished structure

A few hours later, with achy arms and hungry bellies we had successfully moved and positioned the giant piece of oak onto the impressive looking leaky wooden structure. After the hard work it was really satisfying to see the structure in its final completed state. I was equally satisfied to see it in action a few days later when very heavy rain hit this part of Kent. The stream responded rapidly to the rain (due to the geology and topography of the area) and the LWS was really effective in holding back a large volume of water and slowing the flow of the stream.