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RIVER KENNET:
A strategic approach to
restoration and assessment Dr Judy England, Paul St Pierre and Tim Johns
30 April 2013
Contents
Rivers Kennet & Lambourn
Restoration Plan
Monitoring - results so far
Future work
Rivers Kennet & Lambourn:
River Kennet & Lambourn – SSSIs
Lambourn – SAC
Unfavourable condition partly due to physical modifications
Early restoration work undertaken by Thames Water, 1999 – 2002
On-going projects
Strategic Restoration Plan 2011
Restoration Plan:
Strategic “whole river” approach:
Identify key habitat features linking fluvial geomorphology
& ecology
Phased approach
Targeted monitoring
Will also address WFD obligations & climate change adaptation
Results so far – The early work
2011 Nigel Holmes reviewed 6 early projects
Demonstration project – Kennet at Durnsford Mill
Results so far – The early work:
River narrowing, ledge creation
Flow deflectors – post & wire & experimental straw bales
Experimental planting of Phragmites.
Results so far – The early work
Findings:
“as built” state was as planned
overall view in 2011 it was a success.
Lessons Learnt:
Ledges still intact & narrowing the channel – extensive
growth of Ranunculus.
Deflectors worked in the short term but now rotten & defunct.
Adaptive management was undertaken by land manager -
including tree work & replacement deflectors
Results: Hunts Green Fishery
Source: Cain Bio-Engineering Source: Austen Poll
Restoration work by Cain Bio-Engineering, 2006
1) To return the reach to ‘favourable’ condition i.e. • Re-establish Ranunclus Community
• Re-establish Hydromorphological Dynamics
• Increase Velocity and Diversity of Flows
• Increase Habitat Heterogeneity
2) Combat Signal Crayfish infestation i.e. • Reduce Length of Burrowable Banks
• Reduce Crayfish Habitat
Source: Poll (2012) Post-Restoration Assessment on the River Lambourn: Impacts on
Hydromorphology, Habitat and macroinvertebrate Community MSc Thesis
Study: Assess hydromorphological change & macro-invertebrate response by comparing the restored section with unrestored (control) sections.
Control Restored
Hydrological profiles.: - channel narrowing increased maximum & average velocity
Substrate comparison – increase of gravel
Increased heterogeneity – habitat patchiness
Increase in Ranunculus.
Increased biotic scores – LIFE & PSI
Source: Jarque (2012) Post-restoration assessment of the River Lambourn: impact on
the macrophytes and habitat MSc Thesis
Study: Assess the impacts of restoration on plants and
habitats by comparing the restored section with
unrestored (control) sections.
Channel narrowing increased flow velocity, increased scour & reducing silt.
Flow deflectors & gravel riffles created variation in flow types & increased habitat heterogeneity.
Bank stabilisation decreased - signal crayfish burrows & reduced in-put of fine
Increased richness of in-channel flora in comparison with the control reach.
Vegetation Mapping
Lessons Learnt so far:
The importance of thinking about post project appraisal at the start:
Clear project aims & objectives
Clear monitoring aims & objectives
Decent baseline information
Inform adaptive management
Share the lesson’s learnt
Practical River Restoration Appraisal Guidance
for Monitoring Options (PRAGMO)
Future work:
Habitat mapping – functional/biotope
Invertebrate monitoring
Replicated BACI
Lambourn Welford
Lambourn Weston
Kennet Eastridge
www.therrc.co.uk
Practical River Restoration Appraisal Guidance for
Monitoring Options (PRAGMO)
Environment Agency :
WTenquiries@environment-agency.gov.uk
Thank you for listening
rrc@therrc.co.uk 01234 752979 www.therrc.co.uk
Scaling up our Aspirations for River Restoration and
Management
14TH ANNUAL NETWORK CONFERENCE
The RRC would like to thank the sponsors of the RRC Annual Conference 2013 who support discounted places
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