phase 2 river restoration strategy nigel holmes conroy ...nigel holmes with eddie bradbrook, richard...

River Darent Action Plan

Phase 2 – River Restoration Strategy

Nigel Holmes

with Eddie Bradbrook, Richard Andrews, Chris Conroy, Ian Humpheryes, Dave Best, Bridget Thorn

Where is

the

Darent?

Problems: Historical Groundwater Abstraction

Problems: 1976; 1984; 1989-91

Chalk Stream with a difference

Darent Daily Flow at Otford

0

5

10

15

Jan-

87

Jan-

88

Jan-

89

Jan-

90

Jan-

91

Jan-

92

Jan-

93

Jan-

94

Jan-

95

Jan-

96

Jan-

97

Jan-

98

Jan-

99

Jan-

00

Jan-

01

Jan-

02

Date

Flo

w (

cu

mecs)

Hydrograph of a Real Chalk stream - Itchen

Daily Mean Flow on the River Itchen at Allbrook and Highbridge

0

5

10

15

20

25

01.10.

1987

15.03.

1988

28.0

8.19

88

10.02.

1989

26.0

7.19

89

08.0

1.19

90

23.0

6.19

90

06.12.

1990

21.05.

1991

03.11.19

91

17.04.

1992

30.0

9.19

92

15.03.

1993

28.0

8.19

93

10.02.

1994

26.0

7.19

94

08.0

1.19

95

23.0

6.19

95

06.12.

1995

20.0

5.19

96

02.11.19

96

17.04.

1997

30.0

9.19

97

15.03.

1998

28.0

8.19

98

10.02.

1999

26.0

7.19

99

08.0

1.20

00

22.0

6.20

00

05.12.

2000

20.0

5.20

01

02.11.20

01

Flo

w (

cu

mecs)

Abstraction: effects on flow

Naturalised flow

Actual

Flow

Abstraction:

effects on

flow

Actual Flow

Naturalised Flow

Distance down the Darent

Historical Channel Degradation

Water Quality

• Phosphates low – below EN’s SSSI Target

• Nitrates OK – within WHO Drinking Water limits

• Occasionally high BOD due to ‘weed growth’ in

hot summers

• Minor point-source small incidents

• Silt is a problem

• Around 1900 catastrophic pollution ‘killed every

living thing in the river’ - previously considered one

of finest trout rivers in the country

The Darent Action Plan – Water Resources

• Two Phases

• Phase I (1996) – Reduction of 20 Ml/d from

upper catchment & augmentation in low-flow

periods in vulnerable lower reaches

• Phase II (2005) – Further reductions of 23.5

Ml/d from lower catchment sources

• Modelling and other studies to determine an

‘Environmentally Acceptable Flow Regime’

(EAFR)

The Darent Action Plan – Reduced Licences

Daily licensed abstraction accretion profile. Public water supply abstraction in the Darent Catchment upstream of

Dartford in relation to the Darent Action Plan. Reductions in bold type.

0

20

40

60

80

100

120

140

160

180

200

-2 4 10 16 22 28

Distance from start of main river (km)

Lic

en

ce

d a

bs

tra

cti

on

(M

l/d

ay

)

Pre-Phase 1 (1994-97) quantities /yr

Current Quantities (2004) /yr

Proposed Quantities with phase 2 reductions (2007)/yr

Augmentation

Westwood

Westerham Brasted

Sundridge

Cramptons Rd

Kemsing (Honeypot

Stream confluence) Lullingstone

Eynsford

Stansted

Ridley

Hartley

(aggregated)

Horton

Kirby

Fawkham

Green St

Green

Darenth

Wilmington

Oak Lane

Da

rtfo

rd

Lulli

ngsto

ne

Eynsfo

rd

Farn

ingham

Hartley (b)

The Darent Action Plan – EAFR

The Darent Action Plan – Restore flows and

augment in extremes

The Darent Action Plan – EAFR

• At What Cost? – c£75m+!!

• Is it Enough (ecologically)?

• How do we get best value for money?

………………HAVE A SUSTAINABLE AND

ALL-EMBRACING CATCHMENT

MANAGEMENT STRATEGY

River Darent Restoration Strategy

• Builds upon previous plans and actions.

• Primarily building on improved flows.

• Acknowledges more needed if environmental quality to be restored.

• Two parallel studies required to progress a ‘River Restoration Strategy’.

River Darent Restoration Strategy – The 2 Studies

• Both essential to implement sustainable management and restoration.

• Both provide concise outputs.

• Outputs include consultation documents enabling the general public, and other project partners/stakeholders, to become involved in the most cost-effective manner.

• The focus is the River’s ecology – through consultation this ‘backbone’ will be fleshed out with all interests fully integrated in the future

River Restoration Strategy – Study 1

Assess, and report on, the ecological status of the river, its limitations and potential.

review of all available ecological data;

assess the practices and pressures influencing ecology;

consideration of existing environmental responsibilities, and specifically assessments required under the Habitats Regulations (HR) and the Water Framework Directive (WFD).

output = ‘River Darent Environmental Appraisal’.

Volume 2 ‘Draft River Darent Restoration Strategy; programme of Actions and Measures’

reviews achievements of the Darent Action Plan (WR);

assesses how catchment land-use, water resources, flood defences and other activities could be managed in the future in an integrated and sustainable manner;

Preparation of a Strategy and Plan that will benefit the ecology of the river and its natural landscape assets, its resources for recreation and amenity, and provide cost-effective and sustainable water use and flood management.

‘Feature Interests’ Approach

• Include many key species/habitats of interest/responsibility (e.g. BAP) or of socio-economic importance (e.g. fish)

• Can be used as ‘Barometers of health’;

• If we get it right for these, everything else should be OK;

• They are a basis to monitor – need to know progress being made, and possibly quantified;

• Provides feed-back to functions and organisations that their actions have made a difference!!

The ‘River Darent Environmental Appraisal’ – Data Review - Reporting

• SIMPLE REPORTING FORMAT FOR EASE OF LOCAL INPUT TO DRAFT

– What the current status of ‘feature interest’ is considered to be - (e.g. high, good, moderate, poor or bad)

– How current status varies from year to year – e.g. upward/downward trends or stability.

– The factors considered to be most influential in affecting the present ‘perceived’ status.

Integrated Appraisal Approach – Key Factors –

Assessing ‘Cause & Effect’

A.

Habitat

Quality

Also consider others – e.g. catchment effects (siltation), factors out of catchment (estuary netting) Etc.

C.

Water

Quality

Feature Interest being

assessed

B.

Water

Quantity

D. Biological

Interactions &

Responses to

Natural Change

The Darent Strategy – 1. ‘Feature Interests’

Feature Interest

Otter

Water vole

Salmon

Lampreys

Bullhead

Trout and grayling

Other fish communities

Invertebrate communities

Crayfish

Macrophyte community

River Habitat

The Darent Strategy – approach – 5-scale

assessment of status

Colour code Natura 2000/EN definitions

for SSSIs

Water Framework Directive

Status

Additional Darent context

RED: Destroyed/Part

Destroyed/Unfavourable and

Declining

Bad (severely degraded

[HMWB])

Destroyed/At risk

ORANGE: Unfavourable and

Maintained

Poor (significantly changed

from pristine)

Poor condition – has been

much better in past

YELLOW: Unfavourable and

Recovering

Moderate (moderately

changed from pristine)

Also includes Naturally

moderate or worse

GREEN: Good (slightly departing

from pristine)

near-favourable or close to

maximum potential

BLUE: Favourable. High (pristine or near-

natural)

Healthy and not at risk

Score Description of extent of

influence on status

5 Probably key influence

4 Major influence

3 Important influence

2 Moderate influence

1 Minor influence

Blank or not cited None or not known

The Darent Strategy – approach – 5-scale assessment

of factors affecting status

The Darent Strategy – Standard approach to

reporting

• Data Sources.

• Expert Opinion Sources.

• Status between Otford & Dartford.

• Basis for Status Category.

• Comparison of Present Status with

Historical Status.

• Key Factors Affecting Status.

• Actions.

The Darent Strategy – Results of Environmental

Status using surrogates

Feature Interest Status

Otter Unfavourable (no significant change in past 20 years)

Water vole Unfavourable and maintained (no significant change in past 20 years)

Salmon Naturally Unfavourable?? (no significant change in past 20 years) – May be naturally

unfavourable, or historically impacted

Lampreys Probably Naturally Unfavourable (no significant change in past 20 years)

Bullhead Favourable - Not adequately known - probably recovered in past 10 years

Trout and grayling TROUT: Unfavourable (V. slight recovery) GRAYLING: Unfavourable

Other fish communities Moderate except in, and after, major drought years

Invertebrate communities Unfavourable (recovering)

Crayfish Unfavourable (declining [destroyed])

Macrophyte community Near-favourable or close to maximum potential

River Habitat Full range from Unfavourable to locally Near-Favourable

The Darent Strategy –Factors affecting

Ecological status – Matrix Approach

Feature Interests/Factors O WV S L B TG O

F

I C M H

Historic changes to channel form and present character 2/2 5 2 2 2/2 2 5

Flood defence management 1/1 2/2 2 2 2 3 3 2 2/2 4

Channel and other fisheries management actions 1/1 1/1 1 1/1 1/1 1/2 1/3 1/1 2/2 1

Siltation of gravels 4 ? 1 3 2 2 2 2

Periodic drying 4 4 4 4 5 5 5 4 5 1

Extreme low flows - 2 4 2 4 4 4 3 3 3

Present general water quality 1 1 1 2

Historic catastrophic pollution ? 4 4 1? ? 2?

Estuary quality 2

Alien species – e.g. fish stocking 5 2 5

Catchment/floodplain land-use 3/2

Distant effects (sea/estuary- salmon) 2

Specific effects 5 5 5 5

The Darent Strategy –Factors affecting

Ecological status

Type of Impacts

Historic changes to channel – Severe for Salmon and River Habitat

Flood defence management – Moderate for Many things

Fisheries management actions – positive or negative for most

Siltation of gravels – Fish and invertebrates especially

Periodic drying – catastrophic for fish and inverts, and macrophytes??

Extreme regular low flows – bad for everything

Present/recent water quality – not an issue

Historic catastrophic pollution event – legacy difficult to quantify

Alien species – catastrophic for crayfish -

Catchment/floodplain Land-use – otter (roads)

Outside catchment effects – salmon – probably not an issue

Species-specific effects – crayfish, water vole, salmon, native Darent fish

The Darent Strategy – Ecological Status and

Factors Determines Strategy - Headlines Key Impacts Proposals to Reverse Impacts

A. Historic changes to channel Developing a catchment-wide river restoration strategy. Addressed through a comprehensive programme of river

restoration/rehabilitation (Actions). At local ‘hotspots’ in urban areas this may require significant engineering; in others, gentle

actions only to kick-start natural recovery.

B. Flood defence management Establishing, and adopting, a strategy of carrying out necessary maintenance in >99% of the river using only environmental best

practices which will enable the river to help repair itself.

C. Fisheries management actions Through the FAP, develop and adopt a strategy for self-sustaining fish populations and fisheries. Actions will include any river

enhancements that use best practice options only that optimize how river processes can be harnessed to restore desired habitat

structure for fishery and other interests (assisted natural recovery). It also includes re-establishing Darent progeny and enabling

them to be self-sustaining (e.g. EA/DVTF incubator introductions from upstream of Chipstead).

D. Siltation of gravels Addressed through strategies and actions regarding catchment and channel management strategies and actions cited for A, B, C

and K.

E. Periodic drying Being addressed through DAP. A strategy needs to be in place to address problems if the perceived improvements do not

materialize. Specific actions to await this appraisal through CAMS and response of river to next major drought (due soon). F. Extreme low flows

G. Present/recent water quality Continued vigilance of EA in their consenting and regulatory roles. No new strategy or actions required.

H. Historic catastrophic pollution event Legacy; outside the Scope of the RDRS.

I. Estuary quality Outside the Scope of the RDRS.

J. Alien species Strategies to be developed on how to respond most effectively to individual threats. Addressed then through targeted actions

for each one, on a priority basis, but only hope of success is through an integrated catchment approach.

K. Catchment/floodplain land-use Requires both ‘catchment-wide’ and ‘reach’ problems addressing through a coordinated programme of actions. Priority actions

addressing the major problem areas to be determined through a whole catchment strategy to silt reduction.

L. Outside catchment effects Outside the Scope of the RDRS.

M. Species-specific effects Addressed through specific actions. There will be an over-arching strategy to undertake actions that will address specific, and

reversible, factors that adversely impact key interests. The individual actions to be very limited as the thrust of the RDRS is to

undertake integrated management activities that benefits all interest, negating the priority for actions for specific species except

where they alone are seriously impacted (e.g. otter, crayfish).


Factors Determines Strategy - Headlines

Key Impacts Proposals to Reverse Impacts

A. Historic

changes to

channel

Developing a catchment-wide river restoration

strategy. Addressed through a comprehensive

programme of river restoration/rehabilitation

(Actions). At local ‘hotspots’ in urban areas

this may require significant engineering; in

others, gentle actions only to kick-start

natural recovery.

B. Flood

defence

management

Establishing, and adopting, a strategy of

carrying out necessary maintenance in >99%

of the river using only environmental best

practices which will enable the river to help

repair itself.


Factors Determines Strategy - Headlines

M. Species-

specific

effects

Addressed through specific actions.

There will be an over-arching strategy

to undertake actions that will address

specific, and reversible, factors that

adversely impact key interests. The

individual actions to be very limited as

the thrust of the RDRS is to undertake

integrated management activities that

benefit all interest, negating the priority

for actions for specific species except

where they alone are seriously

impacted (e.g. otter, crayfish).


Factors Determines Strategy

Strategy Description

Developing consensus, partnership involvement, and adequate funding to implement the RDRS over a >10 year period.

Reduce/control abstractions to a level that approaches the EAFR.

Improve channel habitat, landscape and broad ecological quality. This should reflect the improved flows due to the DAP I &

II measures, and assist the river to become self-sustaining in the future and ultimately require minimal intervention.

Develop a long-term, catchment-wide, strategy for river rehabilitation in partnership with local communities, riparian

owners, fishery associations etc. See 7.14.

Implement a phased programme of river rehabilitation, addressing improvements to totally degraded sections, blighted

urban areas with high aesthetic and public recreational potential and generally improving habitat throughout the river.

Develop a FAP, that has at its heart, measures to create a sustainable fishery that maximises the biodiversity, recreation and

socio-economic value of the mixed fishery potential. Everything should be delivered through the FAP, which also needs to

link closely to the whole RDRS. Continue/extend re-introduction of Darent progeny fish in line with the EA Trout &

Grayling Strategy.

Implement limited actions to benefit individual species interests. The focus of the RDRS is to protect the good habitat and

improve the rest for the benefit of all environmental interests of the Darent. However, some measures the help recovery of

key species of chalk rivers may be required.

Develop, a strategy for silt management and implement measures required to address the problems.

Review and monitor achievements against targets.

The Darent Strategy – Ecological Status & Factor

Assessment leads to Actions Set within a Strategy

ACTION 3a. Establish, and issue, a clear policy statement on

river maintenance that meets flood defence needs but minimises

intervention.

This is the means whereby potentially good reaches get better for free, and some

improvement occurs elsewhere. Implement immediately, but in consultation with

interested groups and a series of public meetings/leaflet productions etc. to maximise

acceptance and encourage good river management by owners and occupiers.

Contribution to National Chalk River BAP: 2.2, 2.3, 5, 13.1.

Contribution to Kent Area Chalk River BAP:

Priority: imperative

The Darent Strategy – river maintenance



ACTION 4a. Prepare a long-term, catchment-wide, programme

of river rehabilitation in partnership with local communities,

riparian owners, fishery associations etc.

Programme to address how, and where, phased improvements to urban and rural

sections should be tackled, and set priorities. All improvements (e.g. for fisheries – see

7h-7j) would be included within this integrated programme. The programme would

set measurable targets. Demonstration reaches are recommended to help build

confidence, including ones in urban areas for full public enjoyment.

A key need is to develop a programme that includes both significant intervention for

severely degraded sites that cannot recover naturally, and sites where minimal

intervention is needed to assist natural recovery.

Contribution to National Chalk River BAP: 2.2.


Priority: imperative.



ACTION 5a. Implement river rehabilitation according

to the programme developed in 4a.

A rolling annual programme of works to be in place for 10 years,

addressing highest priority, full consensus, areas first, and then

areas where partner confidence required before support given.

Contribution to National Chalk River BAP: 2.3, 5.


Priority: very high.

The Darent Strategy – RestorationExamples Prepared

phase 2 river restoration strategy nigel holmes conroy ...nigel holmes with eddie bradbrook, richard...

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