9. Channel restoration - Gadebridge Park

Aims: Involve people with their local waterbodies; Improve wildlife corridors; Manage flow; Work together

Water body: River Gade
Project description

The River Gade has been significantly impacted by historic channel alterations and currently provides poor habitat and low wildlife diversity.  There is an opportunity to restore the River Gade to its original course through Gadebridge Park and to reconnect piped spring water flow to the river, alongside other improvements for people and wildlife.

At present, the River Gade through Gadebridge Park flows down an artificially raised (perched) channel created to supply water to the now demolished Bury Mill.  This means that it is disconnected from its floodplain. Consequently, when flooding occurs in the valley bottom the water remains in the park for long periods of time as it’s unable to flow back into the channel.  The current channel is also slow flowing and often taken over by vegetation growth due to being historically straightened and widened, and the effect of the impoundment of the Environment Agency gauging station weir at the bottom of the park. The River Gade also suffers from low flows due to spring flow which is diverted into an underground tunnel (culvert), pressure from water abstraction and being disconnected from the groundwater table.

 

The original line of the river would have been along the valley bottom through the park. This course can still be seen during wet winters, when groundwater rises to the surface where the river should be naturally.  The Environment Agency is working in partnership with Dacorum Borough Council and Affinity Water to look at options to move the river channel back to its original course along the valley bottom alongside other improvements, as detailed below.  

 

Our objective of the river restoration scheme are to:

  •  Improve the river and the adjacent parkland for wildlife
  •  Improve the opportunities for amenity and recreation around the river
  •  Improve resilience to low flow events and climate change
  •  Improve the wildlife of the river so that it supports Good Ecological Status under the European Water Framework Directive
  •  Improve floodplain connectivity, but reduce the impact of flooding - i.e. so water can come onto the flooodplain when it needs to, but that it doesn't sit on the parkland for long periods of time
  •  Address the impact of the gauging station
  • Make the channel easier to maintain for the benefits of people and wildlife

 

Our proposals include:

  • Realignment of the river from downstream of the White Bridge, back to the valley bottom through the park.  This will reconnect the river to its floodplain and to groundwater through the area
  • Re-routing spring flows, which currently run through a culvert (underground tunnel), into the new channel to provide additional flow to the river, increasing its resilience, particularly in times of low flows
  • Replacing the existing Bury Mill gauging station with one on the new channel that will be passable to fish, and have much less impact on the river channel than the present gauging station
  • New footpaths and bridges / crossings across the new realigned channel
  • A new wetland / nature area.

There are multiple benefits of this work for both people and wildlife including a restored chalk stream, removal of a barrier to fish movement, improved amenity for users of the park, reduced flood risk, habitat creation and a reduced management burden for the council.

For more details and updates on how this project is progressing, please visit the website.

 

Project lead: Environment Agency
Project partners: Affinity Water, Dacorum Borough Council
Contact for more information: This email address is being protected from spambots. You need JavaScript enabled to view it.
Project start: 2015

Design by LTD Design Consultants and build by Garganey Consulting. From an original concept by the Herts and Middlesex Wildlife Trust.