Case study:Bocking Blackwater River Restoration

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Location: 51° 53' 9", 0° 33' 37"
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Project overview

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Status In progress
Project web site http://www.essexrivershub.co.uk
Themes Habitat and biodiversity, Water quality, Urban
Country England
Main contact forename Kieren
Main contact surname Alexander
Main contact user ID User:KierenAlexander
Contact organisation Essex Wildlife Trust
Contact organisation web site http://www.essexwt.org.uk
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Project picture

Project summary

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Currently, the River Blackwater (Pant, upstream) is classed under the Water framework Directive as heavily modified with poor potential. It is this assessment that drives this restoration project. This project is funded by the Environment Agencies Catchment Restoration fund and is part of the Essex Healthy headwaters scheme. Physical earthworks are due to commence in Summer 2015.

The site is an urban location and is designated as a local nature reserve. It is locally well loved, being popular with walkers, runners and cyclists. A majority of it is close mown grassland, however,there are significant wilder zones in places which are more typical of a Local Nature reserve.

The main aspect of this project is to enhance the river banks by reducing erosion, poaching and silt inputs, the second is to improve riparian habitat and floristic diversity, as an added benefit there should also be an improvement in water quality produced by filtration of the newly established root network.

The river banks will be restored using a mixture of bio engineering schemes including Coir rolls, willow spiling and bank re-profiling combined with Coir pallets. The Coir pallets and roles will be seeded with a combination of native species including flag iris, purple loosestrife and watermint among others. The current condition of the riverbank is floristically poor with either a monoculture of reeds, nettles or the invasive species Himalayan balsam.

Whilst the project is not specifically targeted to deal with invasive species it is hoped that there will be some benefit derived from introducing increased floristic diversity and extra competition.

The final major element of the project is to protect and enhance a deeply eroded section of riverbank. As this is a steep and heavily degraded slope the use of coir rolls and pallets would not be appropriate. Therefore the design solution decided on was to use willow spilling and use the spoil created from the bank reprofiling works to backfill behind the spiling. The idea is then that overtime the willow roots would bind the bank together preventing erosion and offer shading reducing river temperatures in the river over the summer months.

There is some potential to enhance a wetland area, known locally as the spreads by creating a series of ponds and redirecting an existing drain. This will allow any water to be filtered and settled before entering the river. The ponds overtime will develop into fine habitat and support a number of specialist species.

All the above should add up to the an overall improvement of the local Riverine habitat and an improvement in the general water quality and hydro morphological condition of the river.

Increase awareness of flood issues.

Monitoring surveys and results

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Fixed point photography will be used to monitor physical changes both post and pre work. In addition a baseline survey of macrophytes, invertebrates and water quality surveys – data gathered will include – turbidity, sediment, Ammonia/Dissolved Oxygen/Phosphate using field phosphate sampling equipment. This project site will be resurveyed against baseline at the conclusion of the project in 2015.

Lessons learnt

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There is significant Archaeological interest on the site. With an identified Roman Villa remains in the local area. This adds a significant cost element to the project. Investigations are currently underway to identify the implications for this project but this may make the pond and wetland enhancement uneconomic. Early contact with the local Archaeological unit is recommended.


Image gallery


Heavily eroded site at Bocking Blackwater .jpg
Typical riverbank at Bocking Blackwater.jpg
Wetland site at Bocking Blackwater.jpg
Proposed location of pond.jpg
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Catchment and subcatchment

Catchment

River basin district Anglian
River basin Combined Essex

Subcatchment

River name Blackwater Pant
Area category 10 - 100 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 68
68 m
0.068 km
6,800 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB105037033860



Site

Name Bocking Blackwater LNR
WFD water body codes GB105037033860
WFD (national) typology
WFD water body name Blackwater Pant
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present Yes
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) 450
450 m
0.45 km
45,000 cm
Project started 2012/08/01
Works started 2016/08/07
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 Essex Wildlife Trust Kieren Alexander
Stakeholder engagement and communication Essex Wildlife Trust Kieren Alexander
Works and works supervision Essex Wildlife Trust Kieren Alexander
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure
Hydromorphology Structure & condition of riparian/lake shore zones
Biology Invertebrates, Macrophytes
Physico-chemical Specific non-synthetic pollutants
Other reasons for the project Improvement of a local park and local resources


Measures

Structural measures
Bank/bed modifications Soft engineering solutions, Bank improvement, Channel reprofiling, Bank reprofiling
Floodplain / River corridor Erosion protection, Creation of backwaters, Creation of wetland, Creation of pond
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement) Awareness raising, Citizen participation in the restoration project
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
http://www.essexrivershub.co.uk For more information on this and other projects in Combined Essex catchment

Supplementary Information

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