OVERVIEW OF COASTAL ZONES

Virtually the entire country has been considered to be ‘ coastal’

OVERVIEW OF COASTAL ZONES

Importance of coastlineCoastal Zones as integrated resource cycle

Coastal zones

Coastal resources (Mahe) distribution

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

Threats: HUMAN /CLIMATE CHANGE

-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

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 .

What are the changes? Cont.

Storm surges/Abnormal spring tides

-These have been observed to be on an increasing trend and more intense e.g.. NE Point impacts 2007

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 EROSIONLink 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

Climate change impacts on CZ

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.

Impacts related to changes

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)

Impacts related to changes cont.

ErosionTypical example:Anse Kerlan Praslin (one of worst cases)Considerable loss of land (∞ 50 meters of land)Threatening livelihoods, tourism based stretch.

Before 1990’s After TODAY

Scenario in Seychelles

Possible causes (not scientifically determined)

- Reef destruction 1998 bleaching event.- Changes in current patterns, increase erosion- Negative impacts of numerous groynes over decades.

Scenario in Seychelles cont.

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.

Scenario in Seychelles