Tim and our contractors have now started our restoration work at the Butterhill weir. Dropping the water levels has returned flow and energy to the river. This will allow us to narrow the river, recreate meanders and clean gravels to the river which reflects its natural state, had it not been historically modified for industry.
Why are meanders important?
Many urban rivers, and even some rural, have been artificially straightened to make room for development, agriculture and infrastructure. By straightening the channel, the flow of the river becomes uniform and you lose any variation in the river bed.
For example, trout fry prefer calmer, shallower waters compared to grown fish who prefer deeper pools. These different habitats are created naturally by energy of a river which results in meanders. Water passing through a river flows faster on the outside of a bend than it does on the inside. The faster flowing water scours out deeper pools, ideal for big fish, and the slower water deposits sediment creating shallower areas for fry. The scouring flow then deposits gravel downstream in riffles, an ideal place for spawning fish to lay their eggs.
Wandle Trust Makeover
To reinstate the natural meander, Tim and our contractors from Aquamaintain marked out a new path for the river using stakes (see picture below). The new river edge has been taking shape, with silt from the river and faggot bundles forming the new narrowed bank line. Once finished, this bank will be covered in aquatic plants much like our Hackbridge site – a chance for you to get involved!
Pingback: » Urban river restoration: River Anton, Andover