Channel hopping (31st December 2007)

Channel hopping (31st December 2007)

The Nandos restoration – a pioneering project one year on.

A whole year has past since the Environment Agency’s restoration work on the Quaggy behind Nandos Restaurant in Lee High Road, Lewisham. QWAG has carefully monitored developments, keeping a close photographic record. So what’s been happening?

Nothing could have been worse than what previously existed. But to date, not all of our hopes have been fulfilled. This is unsurprising really for an experimental project in a ‘difficult’ location. The important thing now is to remedy problems and learn for the future. QWAG and the Environment Agency have plans to meet and revisit the site as part of a review of all aspects of implementing the Flood Alleviation Scheme between Lee and Lewisham.

Summer 2006

Summer 2006

1. Summer 2006. Before work started. The Quaggy moves sluggishly over a wide, flat-bottomed, concrete bed. The river is strait-jacketed. It cannot cut a low-flow channel, making it too shallow for fish to migrate upstream. And nowhere can sediment stabilise and support life. Nature is doing it’s best – a few plants are struggling on a ledge just above the river. Only self-seeded buddleia flourishes on the surrounding walls.

November 2006

November 2006

2. November 2006. Work just completed. For structural reasons, the concrete bed had to stay so a low flow channel has been constructed. At least the water now flows briskly. Horizontal baulks of timber bolted in place help direct the river and stabilise gravel brought in to naturalise the bed. To the right, a timber framework fastened to the wall should eventually be colonised by self-seeding native flora. To the left, troughs mounted on the ledge are also for plants. Aquatic and riverside species planted by the Agency and can be seen in the gravel.

January 2007

January 2007

3. January 2007. Rivers are dynamic sytems. Two months on and already the Quaggy has set about altering its course. Gravel and sediment is accumulating in a broad bank to the left pushing the flow channel in the opposite direction.

April 2007

April 2007

4. April 2007. QWAG members take a closer look at what’s going on in the river.

June 2007

June 2007

5. June 2007. Trouble. Planted geotextile mats had been used to try to establish plants and stablise the gravel quickly. But the river doesn’t quite want to meander the way the engineers thought it would and has therefore been trying to scour out some parts of the matting. The result has been that whole sheets of geotextile mat have been disturbed and one (top right) has been washed away completely. No plants yet colonise the timber battens – but this is expected to be a long term process.

July 2007

July 2007

6. July 2007. More trouble. Disturbance has affected a section of geotextile to the left of the channel. Again vegetation has been up-rooted. But river-side plants in the troughs are thriving.

November 2007

November 2007

7. November 2007. One year on. Following heavy rain, the river momentarily fills the entire channel. The banks of sediment bordering the low flow channel are visible under the water. Down stream to the left, at least some aquatic plants have established in the river – a good sign and we hope, with remedial management, a harbinger of future colonising.

Skills

Posted on

3rd April 2015

Make a splash without getting wet!