Dr Danika van Proosdij Dept of Geography Dykelands Strategic Importance for Climate Change Adaptation MCCAP workshop Feb 2013 Outline Extensive low lying intertidal environments Dyking ID: 1022178
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1. Photo Credit: Con Desplanque,Dr. Danika van ProosdijDept. of GeographyDykelands: Strategic Importance for Climate Change Adaptation MCCAP workshop Feb 2013
2. Outline
3. Extensive low lying intertidal environmentsDyking history & subsidenceTruroMonctonSackvilleAmherstWolfvilleWindsorFreshwater floodingGeographical SettingOther areas: Annapolis valley
4. predicted relative sea level rise 1.2 – 1.93 m by 2100 (includes increase in tidal amplitude) (Greenberg et al., 2012; Daigle 2011) Increased frequency & intensity of storm activity Consequences of Climate Change damage to coastal infrastructure increased property loss increased flood risks & potential loss of life coastal erosion freshwater flooding & dam failure
5. Greenburg et al., 2012 RSLR~0.41 – 0.79 m by 2055 Risk of storm surge is therefore predicted to increase
6. Storm Surge impact depends on tide level water level determines duration cause floods & are destructive SLR will increase storm surge effects dykes have either overtopped or breached on numerous occasions
7. Strategic Importance for Climate Change AdaptationSource: Webster et al., 2011Dykes are the second line of defense after coastal wetlands & no longer simply protect agricultural landOver time residential, public and commercial development has taken place on adjacent lands which are now vulnerable to dyke overtopping or breaching. Perceived perception of safetyIt is estimated that temporary delays caused by flooding on the TransCanada Hwy between NS and NB will halt more than $50M/day of trade (Webster et al. 2012).
8. Factors Affecting VulnerabilitySubsidence & isolation from coastal sediment input Isolated from tidal flow and new sediment input, the agricultural soils behind the dyke will compact and subside over time. Foreshore marsh however continues to receive sediment & increases in elevation Results in significant difference in elevation in front & behind dyke Net effect = ponding of salt or freshwater flooding & potential blockage (siltation) of aboiteaux structures
9. one way cannot open at high tide delay FW drainageAboiteaux
10. Truro, NS, March 31, 2003(Photo Claude Barbeau; http://www.novaweather.net/Flood_2003.html)