Managing the Environmental Impacts of Hydropower Scottish R

1
Managing the Environmental Impacts of
HydropowerScottish RD ProgrammeIWRMStockholm
November 2008
2
Overview of thePresentation

• Background
• RD Needs and Scope
• Methods Techniques
• Conclusions

3
SSE Hydropower Generation

• Limited hydro development late 19th early 20th
  Century
• NOSHEB formed in 1943 to provide electricity to
  highland communities
• NOSHEB were privatised in 1989 and became part of
  SSE in 1998
• SSE operate 72 hydropower stations (incl. 84
  major dams hundreds of intakes)
• We generate around 3,200 GWhrs/yr (? 40 of
  current UK renewables)

• Mitigation was highly developed for the time
• These measures focussed largely on salmon
• A new large storage scheme currently being
  commissioned

4
Examples of Existing Mitigation

• There is already significant mitigation on our
  schemes
• These include
• compensation flows
• hands off flows
• freshets
• fish passes
• fish counters
• smolt screens
• smolt traps
• tailrace screens
• adult fish traps
• a hatchery

5
Why does Hydropower matter?

• Plays an important role in combating climate
  change
• very low CO2 lifetime emissions
• storage schemes help manage intermittent supplies
  (e.g. wind)
• European targets have been set for renewable
  energy
• UK Scottish Governments have set ambitious
  targets for renewable electricity and renewable
  energy
• Any reduction in output from existing sites will
  inevitably be made up by fossil fuel fired
  generation
• A recent Scottish Govt. sponsored study
  identified gt650 MW of financially
  environmentally viable new schemes
• Balance of global environmental benefits vs.
  local environmental impacts

6
WFD and Hydropower

• For waterbodies affected by large scale
  hydropower WFD has an objective of Good
  Ecological Potential (GEP)
• GEP is the best ecological outcome that can
  reasonably be achieved given the existing type
  and scale of use
• UK environment agencies are defining GEP in terms
  of the alternative approach (see next slide)
• This means considering if missing measures are
  consistent with the existing scale of use
• This approach is an admission that the basic
  science is not sufficiently well developed
• Even using this approach we are not able to fully
  define measures for some problems (e.g. sediment
  management)

7
Definition of GEP
8
RD Needs and Scope¹

• There is a general recognition that
  hydro-morphology is linked to ecology
• But a lack of empirical data means we are not
  able to predict the ecological effects of changes
  in hydro-morphology with any confidence
• We want to be sure that any measures we implement
  really do work
• This will require
• baseline hydro-morphology and ecological surveys
• long term monitoring following any changes
• SSE has initiated a number of projects to begin
  collecting this data

9
Collaborative RD

• We are in the process of setting up a
  collaborative research programme
• We hope that collaboration will
• pool expertise and resources
• build confidence with regulators and stakeholders
• deliver a better research programme
• Partners include the Scottish EPA and other
  research and academic organisations
• The initial aim is to fund a long term (5yr)
  post to co-ordinate the research and support
  publication of peer reviewed papers

10
Site Based Methods¹

• Geomorphic conditions
• Grain Size Distribution
• Armouring
• Sediment Deficits
• Material finer than 64 mm (gravel) missing from
  many areas
• Clearly some very degraded rivers but tributary
  inputs rapidly improve conditions
• Natural rivers are also armoured need for
  reference conditions

11
Site Based Methods²

• Input data to hydraulic models and equations to
  calculate critical discharges
• This can identify geomorphically effective flows

• Discharges needed to mobilise current beds
  (coarse, stable and armoured) can be extremely
  large (lt700 m3s-1)
• Clear need to look at parallel flow restoration
  and sediment augmentation
• Links to aerial sediment size mapping

12
Aerial Photography Techniques
1. Aerial grain size maps
2. Aerial bathymetry (depth) maps
13
Sediment Grain Size Maps
High resolution digital aerial photography
(e.g. 3cm resolution)
Aerial photo-sieving Can be performed
post-survey. Ground samples / geo-referencing
not strictly necessary. Can be performed on
back-dated imagery.
Ground truth data (grain size samples)
OR
Ground data Requires images and ground samples
to be geo-referenced with differential GPS.
Cannot be performed on back-dated imagery.
Calibrated aerial grain size maps
14
Bathymetry (Depth) Maps
High resolution digital aerial photography
(e.g. 3cm resolution)
Ground Data Requires images to be geo-referenced
with differential GPS. Depth profiles of river
must be taken at site of geo-referencing.
Profiles must be taken on day of aerial survey to
ensure that river level is same as
imagery. Bathymetry maps cannot be produced
without accurate ground control or river level
data.
Ground truth data (river depth profiles)
Calibrated aerial bathymetry maps
15
Habitat Maps
Aerial grain size maps
Aerial bathymetry maps
Other Species? Requires habitat requirements to
be defined
Salmonid habitat requirements (e.g. optimal
spawning grain size of 25-60mm and depth of
250-500mm)
Salmonid habitat map
16
Example Salmon Habitat Map
17
DetailedHabitat Map
18
Salmon Smolt Productivity
Eggs c. 5000 eggs per female
100,000
Fry 0 10 survival egg to fry
10,000
Parr 1 33 survival fry to parr
3,300
Smolt trap data
Smolt 2 50 survival parr to smolt
1,650
(Figures used are for illustrative purposes only)
19
Conclusions

• There is a clear need to improve our
  understanding of the links between
  hydromorphology and ecology
• We are attempting to combine traditional ground
  based methods with aerial survey / remote sensing
  techniques
• The initial results look very positive
• The next steps will be to
• compare habitat map based predictions with field
  data (e.g. smolt numbers)
• try to develop habitat maps for other flora /
  fauna
• try to develop the aerial techniques further
  (e.g. flow velocity)
• If the method works we will apply it at more
  sites and revise our operational practice where
  we can