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