phase 2 river restoration strategy nigel holmes conroy ...nigel holmes with eddie bradbrook, richard...
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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).
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.
The Darent Strategy – Ecological Status and
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).
The Darent Strategy – Ecological Status and
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
The Darent Strategy – Ecological Status & Factor
Assessment leads to Actions Set within a Strategy
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.
Contribution to Kent Area Chalk River BAP:
Priority: imperative.
The Darent Strategy – Ecological Status & Factor
Assessment leads to Actions Set within a Strategy
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.
Contribution to Kent Area Chalk River BAP:
Priority: very high.
The Darent Strategy – RestorationExamples Prepared