Salix worked with Natural Resources Wales at Cwmparc in the Rhondda Valley to renaturalise the water courses in order to reduce flood risk and increase biodiversity.
In the 1970s many of the rivers in the South Wales valleys were concrete and block lined to rapidly drain old colliery sites; the result has been a massive reduction in biodiversity and increased flows.
The blockstone river beds increase the speed of the water such that it scours out any gravel, leaving no habitat for invertebrates and thus reducing biodiversity.
The natural processes within the river are now being restored using large woody debris and locally sourced brushwood fascines.
Trapping sediment and slowing the flow
By securely pinning large sections of woody debris in the watercourse to create dams, the flow becomes more like that of a natural river or stream, with pools and eddies developing, areas of sediment building up and variances in flow rates within the channel.
Not only does this slow the flow, giving the catchment area downstream more time to absorb and convey water, but it also provides habitat for a wide range of invertebrates, fish and amphibians.
In contrast, the existing stone or concrete lined channels are largely devoid of life, as the speed of the water washes everything away.
If biodiversity within the steam is improved, other wildlife will also benefit and there is the potential for otters to feed along these watercourses in the future.