IN-RIVER WORKS - KNUTSFORD PLAYING FIELDS

Knutsford Playing Fields are owned by Watford Borough Council, located on the River Colne, and bordered by land owned by Affinity Water on the adjacent bank. It is a popular location for local residents, containing a rugby field, playground, outdoor Green Gym space, plus a viewing platform over the River Colne. This section of the river is designated as a Local Wildlife Site 84/014 for Flowing waters (rivers and streams); species.

Current site issues:

Disconnection with the natural floodplain
A lack of flow diversity, which impacts sedimentation transportation and deposition
A lack of sunshine which negatively impacts floral biodiversity
Presence of non-native invasive species and water quality issues

Proposed solutions:

A series of in-channel features have been proposed including, a combination of berms, flow deflectors and hinged trees to improve habitat diversity and increase species which can thrive in the river.

Flow diversity is vital for a healthy river, as faster water increases scouring of the river bed, which in turn cleans the gravel of sediment. It also oxygenates the water, creating an ideal spawning ground for aquatic creatures. In contrast, slower flows enable sediment to be deposited for other species to thrive. See below image.

The lack of sunshine over the river corridor is being addressed through small tree works, aiming at creating a 60:40 ratio of sunshine and shade. A balance of tree cover is important, as shaded areas help to maintain in-channel oxygen levels and temperatures, especially during times of low flow in the heat of the summer. Sunlit spots are the perfect places for aquatic and riparian floral species to thrive, acting as a buffer protecting the bank erosion and providing food for fauna.

The ground underneath Knutsford Playing Fields is a historic landfill, which prevents the river connecting with its natural floodplain, exacerbated by the steep river banks. However, an exciting opportunity was identified during the design process – meander the river through Affinity Water land! This will reconnect the river with its natural floodplain, while simultaneously addressing water quality and flood alleviation. It also provides an opportunity to introduce a reed bed, which is a rare habitat in Hertfordshire. This option is being investigated further as the design process progresses.

To see the Knutsford Playing Fields Improvement design drawings, click here for South. The Northern improvement design drawings will be added soon. To learn more about our Northern Site plans, return to the main page.

Please note: these plans are subject to change due to as yet unknown challenges we may face during the works period.