2006 05 Severn Estuary Perspective - Roger Wade, Environment Agency
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This document discusses the potential impacts of climate change on the Severn Estuary region. It outlines direct impacts such as increased flood risk and coastal erosion as well as impacts to habitats and water resources. Indirect impacts include effects on renewable energy production, aggregates dredging, and tourism. Specific concerns mentioned include increased flood damage by 2080, coastal erosion under high emissions scenarios, changes in bird and fish populations, effects on water resources like salt water ingress and dredging costs, and pressures from aggregate dredging and housing demand.
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2006 05 Severn Estuary Perspective - Roger Wade, Environment Agency
- 1. The Severn Estuary and Climate Change 1st Severn Estuary Forum 8th June 2006. Dr Roger Wade Environment Agency Wales.
- 2. My talk…... • Direct Impacts of climate change – Flood Risk Management/ Coastal erosion – Habitats – Water resources • Indirect impacts – Renewable energy resource – Aggregates (new build) – Leisure.
- 4. Damage from Flooding- 2080 at 700ppm CO2 and 550ppm CO2.
- 6. fisheries Pre-June (Spring) salmon rod catch, River Wye 1950-2004 0 1000 2000 3000 4000 5000 6000 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2001 No.ofsalmon
- 7. Changes in bird numbers
- 8. What is in or out? • Ten year trends % • Dunlin -23 • Bewick Swan -75 • Whooper Swan 22 • Shellduck -59 • Redshank -1 • Gadwall 82
- 9. Water resources- Lower Summer flows? • Salt ingress • Dredging costs • Oxygen depletion • Salmon Migration
- 10. Renewable Energy- Barrage ???
- 11. Aggregates dredging • Domestic energy reduction = new houses= aggregates • Welsh demand largely from Bristol Channel • Possible erosion to beaches and cliffs • Further pressure inland
- 12. Warmer- good for holidays?
Editor's Notes
- Thank you for the introduction - and good morning. As I have only 10 minutes or so I will go straight into my talk- which does combine 2 of my real interests- Climate Change and the Severn Estuary.
- I am going to cover some of the direct impacts of Climate change- and some of the more indirect pressures on the estuary resulting from climate change. The direct impacts include Flood risk management water resources issues and changes in Biodiversity. The indirect impacts include the pressure on the estuary for renewable energy, aggregates and leisure facilities.
- CHANGES TO THE CLIMATE-you will have had some of this already - but to recap I have 1 slide The climate change-Winters will be wetter and milder Summers will be hotter and drier. Increased temperatures and high summer temperatures will be more frequent.. Intense winter rainfall (up 20% more) and increasing frequency and intensity of storms and flooding. Sea levels will continue to rise (from ice melt and warming) and storm surges will increase in intensity and frequency. Warming of the oceans is also changing the ecology of our seas and warming of the earth has released cold water into the arctic which may have affect ocean currents. The additional CO2 in the ocean could also affect species diversity and especially species such as coral due to the increase in acidity. Whatever we do to mitigate- some of this is in the system- there will be changes.
- These graphs show predicted damage within 10km squares under different situations (relating to Carbon Dioxide levels in the air). For the worst of the 2 scenarios there is a significant increase in flooding damage around the estuary- which is among the most affected in England and Wales. Even within the best scenario there is still a significant issue around the estuary with with key areas of concern being the , Gwent and Somerset Levels.. For flooding in Wales the costs are expected to go from around £70million now to a maximum under the high scenario of over £1000- up to 18 fold increase.
- Coastal erosion has also been studied in the foresight report. . The Severn Estuary is extreme in the map shown- along with the Thames and parts of the East Coast.
- Although the evidence for relating reduction in salmon catches to climate change is more tenuous than some other indicators the reduction is coincident with the major changes seen in temperature over the last 30 years. The impacts may result from changes in the feeding grounds- although there is real concern the Salmon may not be able to cope with higher temperatures. The residual flows of fresh- water are also important for inducing salmon migration. With lower rainfall in summer it is predicted that low flows could drop by up to 50%-again putting real pressures on migratory fish.(some more on this later)
- Over the last 10 years distribution of 8/9 wading bird species has changed.- moving eastwards or northwards. 4 can be explained by a model which relates to wind speed and minimum temperature. Severn estuary SPA used to hold 4% of the international population of Dunlin but numbers have considerably declined in recent years and it is feasible that numbers of Dunlin could dip below the internationally important threshold in future. With rising sea level the feeding grounds within the estuary could be reduced- although with the large tidal range this is not as large an issue as in most estuaries.(Unless the barrier is built!)
- I do not have specific figures for the Severn estuary unfortunately but the wetland bird survey shows some fascinating trends and differences across the UK and some of this is very relevant to the estuary. The picture is not consistent- while the Dunlin and Bewick Swan have seen decreases there have been significant increases in other species such as the Whooper Swan and Gadwall. It is still too soon to say whether this is all climate change- and indeed if it will be applicable to the Severn.. But it may give us some idea of the changes to come.
- It has been predicted that summer low flows in rivers may reduce by up to 50%. This could have significant impacts for several estuary processes and resources. Salt water is likely to penetrate further up the estuary- requiring more control at the Gloucester intake to the Gloucester Sharpness Canal (and Bristol water intake) This will also increase the silt levels round Gloucester and potentially affect navigation in that area. The resuspended sediment also has an oxygen demand when the bore picks it up- providing a quality barrier to fish migration. The flow to induce migration has been previously mentioned.
- Another key area for Mitigation is the provision of sites for Renewable energy. The big issue is the Barrage. The Agency, CCW, Natural England and many conservation bodies consider that a barrage is incompatible with the Birds and Habitats Directives and will have significant impacts on protected species and habitats. This is obviously a difficult area and the estuary’s renewable energy potential is likely to be tapped in some way. Although there is a real issue with the extent of aggregate needed for tidal lagoons I personally do not feel that enough background work has been done on their potential which may offer an alternative without the major environmental consequences. A constraints map- as per Tan 8 could be of use for lagoons and tidal current meters.
- The Severn Estuary and Bristol Channel provide significant quantities of the aggregate for Wales . To provide a 60% reduction in domestic C02 emissions will require a significant new building programme. It is then likely that there will be a considerable pressure for aggregates. The concern is increased erosion to beaches and cliffs.
- The increase in temperature and decrease in Summer rainfall could lead to more local holidays. But I am not keen to leave the subject on such a positive note- and in good Jonah mode I would also say that could put pressure on local health care for sunburn - and that’s not even looking at the possibilities of jellyfish stings and other possible beach related disasters! Any questions?