1. Lancaster University Renewable Energy Group Students: Christopher Betteridge, Lawrence Chamboko, Wang Xiaofei Supervisor: Dr George A Aggidis 3/2/2011 An assessment of the environmental impacts of a tidal barrage scheme at Fleetwood

2. Lancaster University Renewable Energy Group Overview Introduction Aims and Objectives Methodology Conclusions Next steps

3. Lancaster University Renewable Energy Group Introduction Located in Lancashire, catchment of 548 km 2 River is 800m wide, with a 200m channel, and 600m of mudflats and sandbars Salt marshes to the west, regularly flooded 3

4. Lancaster University Renewable Energy Group Aim To assess the environmental impacts of a tidal barrage on the Wyre Estuary. To assess the feasibility of implementing a barrage, with regards to the environment. 4

5. Lancaster University Renewable Energy Group Effects on Water Level Fig.1 Typical tidal curves in open and impounded estuary with a barrage P. M. Parker

6. Lancaster University Renewable Energy Group Effects on Water Level Seaward: a) The rise of low water level adjacent to the barrage Landward: a)The rise of the low-water level b)The prolonging of the high-water stand

7. Lancaster University Renewable Energy Group Effects on Water Quality Water qulity parameter Changes caused by barrage Reason Salinty a maximum increase of 5ppt Prolonged retention of saline water Dissovled Oxygen a maximum decrease of 0.5mg/L Redouced water flushing Biochemical Oxygen Demand (BOD) a maximum decrease of 0.9mg/L Increased dilution at low water Ammonia a maximum decrease of 0.3mg/L Increased dilution at low water Phosphorus decrease in Knott EndIncreased dilution increase in Cartford Accumulation over the prolonged retention Table ? water quality impact by wyre barrage

8. Lancaster University Renewable Energy Group Other Implications Land Drainage Bank Shoreline Sediment Movement

9. Lancaster University Renewable Energy Group Emission Reduction Pollutant Coal equivalent (tonnes, Per annum) Carbon dioxide 153,000,000 Sulphur dioxide 1539 Nitrogen oxides 442.4 Carbon monoxide 250 Particulates 115.4 Heavy metals 0.026 Table ? : Atmospheric emissions from coal-fired generation which would be avoided

10. Lancaster University Renewable Energy Group Environmental impacts of tidal barrages on plants Barrages reduce tidal height They can affect the extent of salt marshes which support an array of diverse flora The salt marshes of the Wyre Estuary for example support some endemic species such as the rock sea lavender, the sea aster and the sea purslane which are priority species.

11. Lancaster University Renewable Energy Group The effect of a tidal barrage on nutrients Impounding water behind a barrage also leads to nutrient build up with an increase in nutirients such as nitrogen and phosphorus. Nutrient build up in turn could lead to a bloom in algae and phytoplankton These algal blooms could have both negative and positive ecological impacts

12. Lancaster University Renewable Energy Group Negative impacts These blooms could lead to a decrease in the biological oxygen demand (b.o.d) of the estuarine waters This is due to the high demand for oxygen by the decomposer community, which ultimately feed on the dead phytoplankton from these algal blooms

13. Lancaster University Renewable Energy Group Positive Impacts Any bloom in the estuarine phytoplankton and algae community could lead to an increase in filter feeding invertebrate populations and ultimately to an increase in the density of feeding birds which feed on these invertebrates. Increases estuarine ecological productivity

14. Lancaster University Renewable Energy Group Environmental impacts of barrages on invertebrates Because barrages lead to increases in bod, this affects water quality and ultimately estuarine invertebrate populations. With reference to the Wyre estuarine ecosystem, populations of brown shrimp, edible cockles and mussels could be adversely affected.

15. Lancaster University Renewable Energy Group Overview of the types of vertebrates found in and around the Wyre Estuary Fish and shellfish Birds Marine mammals 15

16. Lancaster University Renewable Energy Group Conservation sites 16

17. Lancaster University Renewable Energy Group Impact on vertebrates Fish and shellfish- Risk of injury by collision with turbine blades, and injury through related hydraulic effects. Changes to water quality- dissolved oxygen, turbidity, contaminants, salinity. Changes to prey resource, habitats, and migration patterns. Noise disruption. Birds- Reduction in intertidal area and a reduction in feeding time. Changes in nesting and roosting areas Possible increase in prey and ease of feeding Mammals- Few effects, possible deterrence from estuary 17

18. Lancaster University Renewable Energy Group Mitigation measures Fish injury- Mesh screens, fish passes, acoustic systems, low speed turbines Birds- Artificial reefs and roosting sites, creation of an alternative habitat to offset lost habitat Mammals- Use of similar schemes as those used for fish (screens, acoustic devices). Nets and barriers could direct animals to passes or pens, where they can be transported across the barrage. 18

19. Lancaster University Renewable Energy Group Impacts of tidal stream, tidal lagoon, and tidal fence devices on vertebrates Fish-Similar, but lesser effects than tidal barrage. Fish can swim around device! Tidal stream devices have the lowest environmental impact. Birds- Lagoons would have similar effects to a barrage, however submerged tidal stream and fence devices are likely to have negligible effects. Mammals- Effects almost identical to that of fish 19

20. Lancaster University Renewable Energy Group Mitigation measures Fish- Mesh screens, behavioural barrier devices, e.g. lights and sound, have achieved 60- 100% diversion rates in tests. Low speed turbines cheapest and easiest option if sufficient power can be drawn. Birds- Alternative habitat would need to be created under the habitats directive. E.g. alternative feeding or roosting areas. Regulation of recreational use of estuary. Mammals- see fish. 20

21. Lancaster University Renewable Energy Group Conclusions A tidal barrage is feasible in terms of environmental effects, so long as adequate measures are taken to mitigate potential adverse effects. The cheapest and easiest method to prevent fish and mammal injury is low speed turbines, however acoustic devices have also been shown to be effective. With regards to birds, any habitat changed or lost needs to be recompensed. Tidal barrages can have numerous positive effects on the environment. Other methods of tidal energy generation have less effects on the environment overall, compared to a tidal barrage. 21

22. Lancaster University Renewable Energy Group Students: Christopher Betteridge, Lawrence Chamboko, Wang Xiaofei Supervisor: Dr George A Aggidis An assessment of the environmental impacts of a tidal barrage scheme at Fleetwood Thank You