Case study:Lowdham NFM

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Location: 53° 0' 40", -1° 0' 22"
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Project overview

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Status Complete
Project web site
Themes Flood risk management, Habitat and biodiversity, Land use management - agriculture, Monitoring, Water quality
Country England
Main contact forename Alan
Main contact surname Graham
Main contact user ID User:Alan Graham
Contact organisation Trent Rivers Trust
Contact organisation web site http://trentriverstrust.org
Partner organisations Environment Agency, Nottinghamshire County Council
Parent multi-site project
This is a parent project
encompassing the following
projects
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Project picture

Project summary

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The villages of Lambley and Lowdham are situated on the Lambley Dumble/Cocker Beck and currently have 200 homes at significant risk of flooding. Several flood events in both villages have taken place in recent years. The watercourse is extremely flashy draining surface water from the edge of Nottingham. It flows in general within a steep sided wooded valley locally called a dumble, opening up as it approaches the villages. As part of the Defra funded NFM Community projects, TRT have been asked to introduce Natural Flood Management (NFM) works which will complement the Environment Agency flood relief scheme for Lowdham in Nottinghamshire. TRT have been able to determine areas suitable for NFM features in a lowland setting on both watercourses and overland pathways. The aim was to reduce peak flood flows, enhance biodiversity, improve water quality and increase community awareness and involvement. Measures included a number of attenuation bunds, leaky barriers, tree planting, de-culverting and floodplain reconnection. Work commenced in January 2018 with landowner engagement and walkovers on the Lambley Dumble and Cocker Beck. Construction commenced in November 2018 with 18m of concrete culvert being removed allowing the creation of a new section of sinuous channel.

Monitoring surveys and results

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Individual NFM features have been monitored using time lapse photography to show how they function during high flows and show how the locations of the work recover and develope. Additional monitoring is ongoing to assess the impacts of NFM measures on suspended sediment concentrations regarding the bunds installed. Two turbidity sondes (one upstream and one downstream) have been installed to achieve this and assess the cumulative impact of the catchment-wide features. Monitoring is continuing into 2020. Initial results indicate a reduction of sediment within the watercourse downstream of the floodplain reconnection. During peak flow the interventions are slowing the flow, pushing water onto the floodplain and reducing peak levels.

Lessons learnt

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TRT felt that although the project was primarily to deliver NFM and evaluate its performance that we would be able to deliver multiply benefits to the waterbody. We have been successful in these aims and have taken a lot of lessons from the project. • Do not under estimate the amount of time needed to engage with farmers, landowners and parish councils. • Not everyone believes that NFM will work and some landowners will refuse to allow you to undertake the work on their land. • TRT delivered over 50 interventions, which proved successful but the number was largely determined by opportunities that arose. For NFM to be really successful it needs to be upscale and delivered on a far broader scale. • It is relatively easy to deliver leaky barriers, but more difficult to deliver river restoration, storage and wetland areas.


Image gallery


De culverted channel.jpg
Leaky barrier in Dumble.JPG
LWM.JPG
Site 25 12.06.19.JPG
Control structure and monitoring.JPG
Constructing new channel.jpg
ShowHideAdditionalImage.png


Catchment and subcatchment

Catchment

River basin district Humber
River basin Lower Trent and Erewash

Subcatchment

River name Cocker Beck catchment (trib of Trent)
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 131
131 m
0.131 km
13,100 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB104028053290



Site

Name
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body
National/international site designation
Local/regional site designations
Protected species present
Invasive species present
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) 6km
6,000 m
600,000 cm
Project started 2018/02/01
Works started 2018/11/01
Works completed 2020/01/01
Project completed 2021/03/01
Total cost category 50 - 100 k€
Total cost (k€)
Benefit to cost ratio
Funding sources Defra funded NFM Community projects

Cost for project phases

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



Reasons for river restoration

Mitigation of a pressure Flood risk management
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor Containment bund to prevent flooding, Tree planting, Floodplain reconnection, Deculverting
Planform / Channel pattern leaky woody dams
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

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

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