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Crisis in Shrewsbury

Crisis in Shrewsbury. Flooding impacts and risk management. Responsibility and management. Under the ‘Water resources act 1991’ the Environment Agency have a duty to... ‘…protect people and resources threatened by river and sea flooding’. Dealing with high risk. Pre-disaster planning

nicholas-carroll
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Crisis in Shrewsbury

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  1. Crisis in Shrewsbury Flooding impacts and risk management

  2. Responsibility and management Under the ‘Water resources act 1991’ the Environment Agency have a duty to... ‘…protect people and resources threatened by river and sea flooding’.

  3. Dealing with high risk • Pre-disaster planning • Preparation • Response • Recovery and reconstruction

  4. Flood alleviation in Shrewsbury • Flood alleviation strategies have been proposed from 1956 to the present day • 1:100 floods cost an estimated £4m • The NRA (now Environment Agency) commissioned the latest study in 1993. • 3 options • Upstream storage • Channel enlargement by dredging • Hard defences (cost effective option - £3.1m)

  5. Floodwater Containment Upstream The River Vyrnwy doubles the River Severn discharge during flood risk periods. Water encouraged on farmland upstream of Shrewsbury at confluence Discharge slowed BUT – rejected on a cost benefit analysis - Compensation to landowners for loss of land = £18 million.

  6. Channel Enlargement by Dredging • This would: • Deepen the river • Increase the efficiency • Allow the channel to contain more water within its banks during periods of peak flow. However, the channel would need to be 35 meters deep! This would be prone to re-silting which would incur even more costs.

  7. Hard defences and drainage modification within the town Defence walls at key locations in the town to hold back flood water. One way valves included to stop water backing up and flooding out of the drains. Cost would be £3.1 million. This was the only option considered cost effective by the EA.

  8. Hard defences... • Planning application was made in 1993 • Proposed scheme… • Include walls, floodgates and ‘one-way’ drain valves in a two phase development… • Phase 1 - Based in Frankwell • Phase 2 - Based on English Bridge • Proposal rejected - May 1996 • ‘unacceptable impact on the town’s river side character’ NRA (1996)

  9. And what happened... • In Oct. 1998 Shrewsbury experienced its largest flood for 30 years (1:60 yr. event) • And in Nov. 2000 Shrewsbury again was devastated by its largest flood for 50 years (1:50-70 yr. event) • EA have acknowledged a significant increase in the frequency of floods events since 1998 (EA 2001)

  10. B4393 Crew Green to Llandrinio Road

  11. Frankwell, Shrewsbury.

  12. Frankwell Car Park, Shrewsbury.

  13. English Bridge, Shrewsbury.

  14. Gay Meadow Football Ground, Shrewsbury.

  15. Renewed calls for action... • Linked to the River Severn Strategy (EA)... • ...the EA have proposed the latest flood alleviation strategy for Shrewsbury. • Based on… • the work in 1993 • the latest flood protection systems • and full communication with interested parties

  16. What is happening? The EA split Shrewsbury into “Cells” – each for consideration and Cost Benefit Analysis - Work is funded by local authorities and grants from Central Government.

  17. Frankwell Housing Car park River Severn

  18. So what’s the latest? • Shrewsbury and Atcham Borough Council granted planning permission for Phase 1 on 4th July 2001... • Formal application made to DEFRA (Department for the Environment, Food and Rural Affairs) for funding... • Accepted - construction work started early 2003 • Completed Autumn 2003

  19. Frankwell – hard defences The scheme incorporated demountable barriers which are only deployed prior to flooding.

  20. Temporary Flood Defences Two other temporary flood defences will be trialled in Shrewsbury Mobile Dam – which consists of two tubes fitted together and filled with water to create a dam.

  21. Temporary Flood Defences Pallet Barrier – which is a metal frame on which wooden pallets and plastic sheeting are placed to retain the water

  22. Defences tested • Defences were tested during the flooding in Feb 2004

  23. Defences tested

  24. Other areas not so protected

  25. Other areas not so protected

  26. Other areas not so protected

  27. Continuing work by the EA... • They await the success of Phase 1 • Phase 2 - English Bridge area - does not currently meet cost benefit requirements. • R. Severn Management Strategy • Continued monitoring... • R. Severn • Climate • Catchment response • Pre-planning (e.g Flood Warnings) • Increase awareness (e.g. Floodline)

  28. Summary of the proposed schemes

  29. Flood defence options

  30. Why locate in high risk areas? • Risk perception • Understanding based on experience • Low frequency of high magnitude events may induce complacency • Knowledge • Benefits outweigh potential costs • Necessity

  31. EIA(Environmental Impact Assessment) • EIA for Phase 1 completed Jan 2001. • Work based in Frankwell, Shrewsbury • Objective analysis of impacts by new developments • Statutory obligation for major projects • Stages… • Problem Identified - national and local relevance • Scoping Report - sets out problems • Consultation, feedback and option evaluation • Planning application with env. action plan

  32. Rejected for aesthetic reasons? or was it something else…?

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