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OVERVIEW OF COASTAL ZONES

OVERVIEW OF COASTAL ZONES. Virtually the entire country has been considered to be ‘ coastal’. Importance of coastline Coastal Zones as integrated resource cycle. Coastal resources (Mahe) distribution. Threats: HUMAN / CLIMATE CHANGE. What are the Changes? Direct impacts? Sea level Rise

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OVERVIEW OF COASTAL ZONES

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  1. OVERVIEW OF COASTAL ZONES • Virtually the entire country has been considered to be ‘ coastal’

  2. Importance of coastlineCoastal Zones as integrated resource cycle

  3. Coastal resources (Mahe) distribution

  4. Threats: HUMAN/CLIMATE CHANGE • What are the Changes? Direct impacts? • Sea level Rise -Obvious retreat in coastlines across Seychelles. -Intensifying storm surges -Intensifying erosion effects • Change in rainfall patterns - Wet season experiencing short patches of intense rainfall -Lead to quick saturation of soils causing top soil erosion of many embankments. -Leads to red earth siltation of rivers and sea water -Impact coral reef

  5. What are the changes? Cont. • Augmentation in Sea Surface temperature -As experienced in 1998, temperature of about 2°C above normal 29°C, lasted for at least five months. - Leading to Intense Coral bleaching - Continuous increase in sea temperatures is inevitable given rate of global warming. - Only imply further bleaching and destruction of coral reefs. • Storm surges/Abnormal spring tides • -These have been observed to be on an increasing trend and more intense e.g.. NE Point impacts 2007

  6. Climate change impacts on CZ • Impacts related to Changes • Coral bleaching Bleaching event of 1998 resulted in 90% loss of total coral cover in Seychelles. Coral death increase its vulnerability to erosion by wave action. Leads to reef destruction, hence increase in incident wave energy approaching the shores= increase EROSION Link to particular study?? On wave energy post reef destruction in Seychelles of 14 fringing reef affected. • Destruction of coastal ecosystems • Costal vegetation, mangrove vegetation destroyed with erosion effects

  7. Impacts related to changes • Coastal flooding - Heavy rainfall often coinciding with storm surges also coinciding with highest tide E.g. 2007 event at North East Point. -Road network damaged, houses flooded, salt water intrusion into marsh affecting species. - Overflow of wetlands (catchments) often invaded with invasive species reducing storage capacity.

  8. Impacts related to changes cont. • Erosion of coastlines. Erosion effects have accentuated at several locations across the main islands (linked to sea level rise, change in current patterns, Reef destruction)

  9. Scenario in Seychelles • Erosion Typical example: Anse Kerlan Praslin (one of worst cases) Considerable loss of land (∞ 50 meters of land) Threatening livelihoods, tourism based stretch. Before 1990’sAfter TODAY

  10. Scenario in Seychelles cont. • Possible causes (not scientifically determined) • Reef destruction 1998 bleaching event. • Changes in current patterns, increase erosion • Negative impacts of numerous groynes over decades.

  11. Scenario in Seychelles • Anse Kerlan Solutions. -Given very dynamic system (cell) best approach turned towards study of area (JICA). Study bathymetry, beach profile, current patterns … so as to determine best solution. -Highly turned towards offshore breakwater (dissipate high wave energy offshore). However extremely costly.

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