Case study:Narborough Rehabilitation Project

Jump to: navigation, search
(0 votes)

To discuss or comment on this case study, please use the discussion page.

Location: 52° 41' 16", 0° 34' 41"
Edit location
Loading map...
Left click to look around in the map, and use the wheel of your mouse to zoom in and out.

Project overview

Edit project overview
Status Complete
Project web site
Themes Habitat and biodiversity
Country England
Main contact forename Nigel T.H.
Main contact surname Holmes
Main contact user ID
Contact organisation
Contact organisation web site
Partner organisations Environment Agency, River Restoration Centre, Natural England
Parent multi-site project
This is a parent project
encompassing the following
just post works

Project summary

Edit project overview to modify the project summary.

River excavations and modifications took three days, the majority of one of these being import of the gravel to the ‘runs’.

Work was implemented in c1km of river. There was absolutely no gradient within the sections modified, with the river being deep and sluggish throughout. Work carried out:

    • created greater diversity of habitat by modifying both the long and cross-sections;
    • locally narrowed the channel to improve self-cleansing of the bed in these locations, and accelerated flow into pools created immediately downstream;
    • removed the unsightly deflectors by replacing them with ‘living’ features that already are doing a much more effective job than the deflectors were attempting to do;
    • the one main difference from the Castle Acre stretch was that some of the upstream ‘runs’ had a thin layer of gravel spread over them too.

Differences in character were primarily determined by the character of the river bed where pools were excavated, and the extent of reed/sedge available from adjacent to the river to add to the channel.

Where the bed was hard, and reed/sedge was plentiful, upstream narrowing could be more extensive. In all cases where the bed was hard (predominantly chalky clay), very distinct pools and upstream ‘runs’ were formed. Where-ever possible the bed of the narrowed channel upstream of the pools was shallowed by adding material dug from the pools – this could only be done where flints or firm clay formed the substrate.

Where the bed was pure soft peat, the distinction between the narrowed channel upstream, and the deepened channel downstream, was much less. Had deflectors not already been present in the channel, it would have been difficult, or impossible, to establish narrowing upstream......the deflectors now form the downstream edges of the shoulders. Without reeds/sedge from adjacent to the river being added to these areas, they could not have been expected to be retained in the long term.

Monitoring surveys and results

This case study hasn’t got any Monitoring survey and results, you can add some by editing the project overview.

Lessons learnt

This case study hasn’t got any lessons learnt, you can add some by editing the project overview.

Image gallery


Catchment and subcatchment


River basin district Anglian
River basin North West Norfolk


River name Nar to confl with Blackborough Drain
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 95
95 m
0.095 km
9,500 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB105033047791

Other case studies in this subcatchment: Castle Acre Rehabilitation Project, Nar SSSI project, River Nar Restoration Project, River Nar, Mileham River Restoration Project, West Lexham Rehabilitation Project


Name Narborough
WFD water body codes GB105033047791
WFD (national) typology
WFD water body name Nar to confl with Blackborough Drain
Pre-project morphology Single channel, Straightened
Reference morphology Single channel, Pool-riffle, Sinuous
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)

Project background

Reach length directly affected (m)
Project started
Works started
Works completed
Project completed
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance

Reasons for river restoration

Mitigation of a pressure
Other reasons for the project


Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Non-structural measures
Management interventions
Social measures (incl. engagement)


Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Monitoring documents

Additional documents and videos

Additional links and references

Link Description

Supplementary Information

Edit Supplementary Information