39. The Moor river improvement project
Themes: Community engagement and participation; Promoting appropriate and sympathetic land management; Improving water quality and water quantity
- Promote the river as a community and educational resource
- Reduce flood risk
- Improve existing wildlife corridors
- Increase the amount and quality of habitat
The Moor river improvement project is one of a number of projects that are taking place as part of the Revitalising Chalk Rivers partnership, in collaboration with the Environment Agency.
Stakeholder engagement is key to the success of the morphological projects along the Upper River Lea and Affinity Water has worked in partnership with Luton Borough Council and the Luton Lea River Catchment Partnership. These improvement works will help to restore and improve the habitat of chalk streams along the River Lea and to meet the EU Water Frame Directive of Good Ecological Potential by 2027.
The channel is generally over-wide, especially at the upstream end, and consequently sediment is deposited on the bed, smothering any gravel that may be present (Figure 1). This is a problem, as gravel is vital for the spawning of many fish species, such as trout, and also supports a wide range of invertebrates. The steep right bank requires re-profiling to allow plants to become established and to reduce the amount of silt entering the river. (Figure 2), the trees on the left (east) bank over shade the river, restricting the growth of in-channel and marginal plants.
Construction started on 6 January 2020, our contractor battled the storms of Ciara and Dennis and the subsequent high river levels to complete the project on time by the end of March 2020.
We constructed a bund to divert the river down the new channel that meanders further into the park. The old river channel now provides a wetland habitat and a buffer from road run-off pollution.
Berms, riffles and pools have been created in the new river channel to provide a mosaic of different habitats for insects, plants and fish.
The river channel has also been designed to be resilient in times of low-flow and has increased the flood capacity of the wetland areas by 700m3 .
The after photos look a bit raw at the moment but given time come the summer the vegetaion will be growing through the coir matting.
The aim of the works is to naturalise the River Lea in Luton as much as possible by carrying out tree works and cut back overgrown trees, to allow sunlight to reach the river and its bank, which will improve biodiversity in the river corridor. Also to reprofile the river banks and re-meander the river channel further into the park (Figures 3 and 4), to create wetland areas and a backwater (Figures 5, 6, 7 and 8), making the river more resilient to low-flows.
This will all help the river meet the requirements of the Water Framework Directive.
Where possible the project will improve the river as an amenity feature for the local community and reduce the risk of flooding.
Figure 1: Looking downstream, a view of the River Lea at The Moor, from the north before restoration.
Figure 2: Looking downstream, a view of the River Lea at The Moor, from the north after restoration, a bund constructed to create wetland in old channel and to divert river into new channel (March 2020).
Figure 3: Looking upstream from the middle of the site, before restoration.
Figure 4: Looking upstream from the middle of the site, after restoration. Water levels still high drowning out the berms that are just visible at the water line on both left and right banks.
Figure 5: Looking downstream to the lower end of the site, before restoration.
Figure 6: Looking downstream to the lower end of the site, after restoration a beach area for people and dogs to access the river (March 2020).
Figure 7: The downstream end of the reach, before restoration.
Figure 8: The downstream end of the reach, river meander further into the park and a backwater created, after restoration (March 2020).