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Blake Lapthorn - Climate Change - green breakfast
 

Blake Lapthorn - Climate Change - green breakfast

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Blake Lapthorn solicitors' Climate Change team held a green breakfast on flooding in the Solent on 16 October 2012.

Blake Lapthorn solicitors' Climate Change team held a green breakfast on flooding in the Solent on 16 October 2012.

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  • Is sea level rise accelerating ?
  • At least 30 years needed to removed decadal variability.
  • Geological land movement: global and regional changes in gravitational field; isostatic adjustment; local changes in wetlands Tsunami: 11 th March 2011 Japan Sendai 10m Storm surges: 1.5 m in English Channel; North Sea 1953 3.9m at Dutch Coast Wind waves estimated of at least significant wave heights of 7.8m off Norfolk Coast in the 1953 event. Astronomical tides – tidal resonance is influenced by sea level rise. Eg Tides in Bristol Channel may decrease their range with sea level rise. Mark Pickering Ivan Haigh showed small changes in the tides in the English Channel due to sea level rise over the 20 th century. River runoff is influenced by the tidal level at the estuary and can cause both fluvial and estuarine flooding. Geological land movement: global and regional changes in gravitational field; isostatic adjustment; local changes in wetlands Tsunami: 11 th March 2011 Japan Sendai 10m Storm surges: 1.5 m in English Channel; North Sea 1953 3.9m at Dutch Coast Wind waves estimated of at least significant wave heights of 7.8m off Norfolk Coast in the 1953 event. Astronomical tides – tidal resonance is influenced by sea level rise. Eg Tides in Bristol Channel may decrease their range with sea level rise. Mark Pickering Ivan Haigh showed small changes in the tides in the English Channel due to sea level rise over the 20 th century. River runoff is influenced by the tidal level at the estuary and can cause both fluvial and estuarine flooding.
  • Geological land movement: global and regional changes in gravitational field; isostatic adjustment; local changes in wetlands Tsunami: 11 th March 2011 Japan Sendai 10m Storm surges: 1.5 m in English Channel; North Sea 1953 3.9m at Dutch Coast Wind waves estimated of at least significant wave heights of 7.8m off Norfolk Coast in the 1953 event. Astronomical tides – tidal resonance is influenced by sea level rise. Eg Tides in Bristol Channel may decrease their range with sea level rise. Mark Pickering Ivan Haigh showed small changes in the tides in the English Channel due to sea level rise over the 20 th century. River runoff is influenced by the tidal level at the estuary and can cause both fluvial and estuarine flooding. Geological land movement: global and regional changes in gravitational field; isostatic adjustment; local changes in wetlands Tsunami: 11 th March 2011 Japan Sendai 10m Storm surges: 1.5 m in English Channel; North Sea 1953 3.9m at Dutch Coast Wind waves estimated of at least significant wave heights of 7.8m off Norfolk Coast in the 1953 event. Astronomical tides – tidal resonance is influenced by sea level rise. Eg Tides in Bristol Channel may decrease their range with sea level rise. Mark Pickering Ivan Haigh showed small changes in the tides in the English Channel due to sea level rise over the 20 th century. River runoff is influenced by the tidal level at the estuary and can cause both fluvial and estuarine flooding.
  • 2mm/year rise in Central Scotland
  • Isopleths are lines of sea level rise from 2000 to 2100 at intervals of 10 years. eg Take sea level of 6.5 m above datum at Newlyn. light grey ( in 2000) shows that 6.5m could be exceeded every 100 years, Whilst in 2100 ( top dark line) 6.5m could be exceeded every 6 months

Blake Lapthorn - Climate Change - green breakfast Blake Lapthorn - Climate Change - green breakfast Presentation Transcript

  • Flooding and sea-level rise in the Solent Region Robert J. Nicholls Faculty of Engineering and the Environment University of Southampton r.j.nicholls@soton.ac.uk South Coast green breakfast series
  • Plan• Global sea-level change – Historic – Future (scenarios)• Relative sea-level change in the English Channel• Flooding in the Solent – Historic flood analysis – Flood modelling
  • < 1mm/year 6mm/year> 20mm/year
  • Global sea-level rise (IPCC, 2007, AR4 WG1))
  • Recent global sea-level rise (IPCC, 2007, AR4 WG1)• Sea-level rise 1961-2003 1.8 mm/year compared with less than 1mm/year over the last 8000 years.• Sea-level rise 1993-2003 3.1 mm/year, but only 10 years !
  • Global sea-level rise (IPCC, 2007, AR4 WG1) 1961-2003 1993-2003Thermal 38% 58%ExpansionGlaciers 45% 28%Greenland 4% 7%Antarctica 13% 7%Total 1.8mm/year 3.1 mm/year
  • IPCC 2007 statement• Climate has changed on all time scales throughout Earth’s history.• The concentration of Carbon dioxide in the atmosphere has reached a record high relative to more than the past half-million years, and has done so at an exceptionally fast rate.• Current global temperatures are warmer than they have ever been during at least the past five centuries, probably even for more than a millennium.• If warming continues unabated, the resulting climate change within this century would be extremely unusual in geological terms.• Another unusual aspect of recent climate change is its cause: past climate changes were natural in origin whereas most of the warming of the past 50 years is attributable to human activities.
  • Future sea-level rise• IPCC 2007 predictions global sea level could be between 18 and 59 cm higher than 1980-1990 levels by 2100.• UK Government has done a subsequent analysis (UKCP09). They have suggested values of 37 to 53 cm for S. England are most likely by 2100.
  • Future sea-level rise• IPCC 2007 predictions global sea level could be between 18 and 59 cm higher than 1980-1990 levels by 2100.• UK Government has done a subsequent analysis (UKCP09). They have suggested values of 37 to 53 cm for S. England are most likely by 2100.• Changes of up to 190 cm are possible by 2100, but VERY unlikely.
  • ?Global sea-level rise (IPCC, 2007, AR4 WG1))
  • Local sea level• Geological Land Movement• Tsunami• River runoff• Storm surges• Astronomical tides• Wind waves and swell
  • Local sea level• Geological Land Movement• Tsunami• River runoff• Storm surges (part of extreme water levels)• Astronomical tides (part of extreme water levels)• Wind waves and swell (not discussed)
  • Geological land movements 1 mm/year sinking
  • Relative Sea-Level Rise• Measures relative movement of the land to the sea – absolute ocean change plus land uplift/subsidence• Measured with tide gauges – digitising records every 15 minutes or hour with quality control rules on missing data• One annual estimate of mean sea level is the mean of > 8,000 measurements.
  • Example Tide Gauges (float gauge) Source: National Oceanographic Centre
  • Sea level in the English Channel• A major data archaeology exercise has been conducted.• Paper-based records: – St Marys, Isles of Scilly, – Weymouth, for – Southampton – Newhaven• Correction of previous errors: – Devonport – Portsmouth• Collectively, about 150 years of data have been added to the English Channel sea-level record. (I.D. Haigh PhD 2009)
  • Mean (and extreme) sea level English Channel data extension Source: Haigh et al, 2009 Continental Shelf Research
  • Mean sea-level (MSL) trends (mm/yr) for 20th Century Station Name MSL trend (mm/yr) St Mary’s 1.72 ± 0.52 Smallest sea level Newlyn 1.74 ± 0.06 rise at Southampton Devonport 2.07 ± 0.63 and Portsmouth Weymouth 1.81 ± 0.28 Sheerness (Thames Southampton 1.30 ± 0.18 Estuary) has higher Portsmouth 1.21 ± 0.27 sea level rise than all Newhaven 2.27 ± 0.27 Channel Ports Dover 1.93 ± 0.21 Sheerness 2.43 ± 0.09 Source: Haigh et al, 2009 Continental Shelf Research
  • Sea level in the English Channel• Mean sea levels and extreme sea levels have been rising at a similar rate through the 20th Century.• The rate of rise is in the range 1.2 to 2.3 mm/yr, with 1.3 mm/yr at Southampton.• Average value is 1.7mm/year – similar to global trends during the 20th Century
  • Sea level in the English Channel• Sea-level rise accumulates and increases the likelihood of flooding during storms – all things being equal.• A water level that on average occurred once every 100 years in 1900 now occurs on average every 10 to 25 years.• As sea levels continue to rise and probably accelerate, this increase in the likelihood of flooding will continue.
  • Sea level in the English Channel Changes at Newlyn (50cm rise in 100 years) Source: Haigh et al, 2011 Maritime Engineering
  • Flooding in the Solent
  • The Solent Flood Plain
  • Southampton Annual sea levels:1935 to 2010 6.0 10 March 2008 Annual extreme 5.0 levelHeight (m CD) Trend = 1.2 mm/yr 4.0 3.0 Mean level Trend = 1.4 mm/yr 2.0 1900 1920 1940 1960 1980 2000 2020
  • 10 March 2008 Source: Haigh et al., 2011, Maritime Engineering
  • 10 March 2008 Source: Haigh et al., 2011, Maritime Engineering
  • Southampton10 March 2008, high tide
  • Sandbanks, Dorset 10 March 2008, high tide
  • Yarmouth10 March 2008, high tide
  • Yarmouth10 March 2008, high tide
  • Yarmouth10 March 2008, high tide
  • Emsworth10 March 2008, high tide
  • Historic flood analysis• What is the relationship between high sea levels at Southampton and Portsmouth and coastal floods? (1935 to 2005 and 1961 to 2005, respectively)• What sites in the Solent that have been particularly flood-prone?• Are there significant changes in the occurrence of coastal flooding in recent decades?
  • Methods (1)• Identify the 100 highest sea levels at Southampton and Portsmouth• Define events that lead to flooding using the newspaper records (The Echo and the News) Event Type Description Category 1 Definite coastal flood event around high tide. 2 Possible flood event, but coastal influence uncertain. 3 Extreme weather event recorded, but no flood occurrence recorded. 4 No acknowledgment of weather or flood event. Source: Ruocco et al., 2011, Natural Hazards
  • Methods (2)• For Category 1 events (certain coastal floods), the severity is defined Severity level Description 5 Flooding over larger areas. Significant pumping required by emergency services. Generally more than half a day disruption to homeowners and road users. More than 15 properties affected 4 More than 5 properties affected by flooding. 3 More than 3 roads affected and/or at least one property affected. 2 Some road flooding – usually localised or shallow. 1 Flooding in open areas/quay areas – no real structural damage or disruption. Source: Ruocco et al., 2011, Natural Hazards
  • Flood events occurrence and severity Event Type Category Southampton Portsmouth 1 58 53 2 10 11 3 5 2 4 27 34 Source: Ruocco et al., 2011, Natural Hazards
  • Flood Occurrence ´ 12 11 10 9 15 13 8 14 23 25 16 20 21 26 7 4 17 6 18 19 5 27 22 24 36 35 34 3 28 1 32 2 37 Number of flood 33 events recorded 28+ 31 20-23 30 16-19 13-15 29 10-12 7-90 3 6 12 Kilometers 4-6 1-3 Source: Ruocco et al., 2011, Natural Hazards
  • The Top 10 Events 1935 to 2005 Date of Number of Southampton Portsmouth flood locations Total sea level (m rank Total sea level rank affected CD) (m CD) 14/12/1989 21 5.34 12 5.21 70 10/01/1993 19 5.48 2 5.36 15 20/12/1983 17 5.34 14 5.43 6 13/12/1981 15 * * 5.42 8 08/12/1954 14 5.38 11 * * 23/11/1984 14 5.29 20 5.48 3 17/12/1989 14 5.25 33 5.21 71 07/12/1994 12 5.46 3 5.5 1 24/10/1961 11 5.41 7 5.41 9 07/10/1987 10 5.24 34 * ** No sea level data is available for these events; hence the rank cannot be determined. Source: Ruocco et al., 2011, Natural Hazards
  • 14/17 December 1989 Flood Fareham ´ Emsworth Lymington Portsmouth Severity of flood 5 4 3 20 5 10 20 Kilometers Source: Ruocco et al., 2011, Natural Hazards
  • Cowes14 December 1989 Flood
  • Extreme sea levels and coastal flooding Southampton Portsmouth Southampton Portsmouth Source: Ruocco et al., 2011, Natural Hazards
  • Flood Modelling
  • Flood Analysis -- Methods Source: Matt Wadey
  • Yarmouth 2008 Flood Source: Matt Wadey
  • Yarmouth Future Flood 2008 Flood plus 0.5 m SLR Source: Matt Wadey
  • Yarmouth Future Flood 2008 Flood plus 0.5 m SLR Source: Matt Wadey
  • Yarmouth Future Flood 2008 Flood plus 0.5 m SLR Source: Matt Wadey
  • Regional Flood AnalysisBuildings flooded to 1-m depth across the Solent in a single tidal cycle 0.5 m rise 1.0 m rise Source: Matt Wadey
  • Planned Adaptation to SLR Source: Nicholls (2010) Book on “Understanding Sea-Level Rise and Variability”
  • Other Adaptation Response Options• Forced/Unplanned retreat• Attack (build seaward)
  • Made Land SouthamptonSource: West, 2011. Solent Estuaries - Introduction: Geological Field Guide. Internet site:www.soton.ac.uk/~imw/Solent-Introduction.htm. Version: 3rd June 2011
  • Concluding remarks• Sea levels are rising globally and in the English Channel, including the Solent.• This will continue and likely accelerate.• This is raising extreme events and threatens more coastal flooding in the future unless we respond.• Many adaptation options are available – especially if we plan now.
  • Acknowledgements• Dr. Neil Wells, University of Southampton, National Oceanographic Centre• Dr. Ivan Haigh, University of Southampton, National Oceanographic Centre• Amy Ruocco, former MSc Environmental Science student (currently URS, Basingstoke)• Matt Wadey, PhD student
  • Questions?
  • Flooding and sea-level rise in the Solent Region Robert J. Nicholls Faculty of Engineering and the Environment University of Southampton r.j.nicholls@soton.ac.uk South Coast green breakfast series