FLANDERS HYDRAULICS RESEARCH FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS Sea level rise and its danger for the Belgian coast ir.
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FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast
ir. Toon Verwaest
ODINAFRICA course – 13 november 2006 – Oostende
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
1. What is Flanders Hydraulics Research?
2. Definition(s) sea level rise
3. Measurements sea level rise
4. Coastal defence from the perspective of sea level rise
5. The coastal landscape from the perspective of sea level rise
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
What is Flanders Hydraulics Research?
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
• service of the Flemish administration (ministry Mobility and Public Works)
• internal consulting
• knowledge area is “water” (ship maneuvring in undeep water, coastal defence, ports, navigable waterways, sluices…)
• physical models, numerical models, measuring networks in situ, databanks, laboratory experiments
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Definition(s) sea level rise
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Reference level on land : “relative sea level” (3 different reference levels)
Relative sea level movements (ca. 10 different phisical processes, taking place on very different timescales and spatial scales)
• time scale < 1 year
• time scale > 1 year “mean sea level”
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Bewegingen relatieve zeespiegel op tijdsschaal < 1 jaar
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Bewegingen relatieve zeespiegel op tijdsschaal > 1 jaar
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Measurements of relative sea level rise
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
1. Relative to the top of quay walls in harbours : maregraphs (100 year data set)
2. Relative to the top of pleistocene subsoil : quartair-geology (10.000 jaar data set)
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
18 cm / eeuw
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
70 cm / eeuw
7 cm / eeuw
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Coastal defence from the perspective of sea level rise
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
• Scenarios of relative sea level rise in 21st century : from only 10 cm to almost 100 cm
• …and the next centuries of the 3rd millenium : ~ 10 m in the year 3000
→ Increase floodable land (the coastal lowlying areas)
→ Increase failure probability of the coastal defence
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Increase floodable land :
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Increase failure probability of coastal defence : ca. 0,5 m higher sea level translates into a factor 10 increase in failure probability !
[ this is because the failure probability of a coastal defence is determined (in large part) by the storm surge level]
… in addition, there are expactations that the storm climate in the North Sea will worsen : more (frequent) extreme winds
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
COASTAL DEFENCE POLICY = GROW WITH THE SEA using SAND NOURISHMENTS
• To protect 1 km of coast ~ for every 10 cm sea level rise 100.000 m3 sand
• flexibel technique (<-> hard coastal defences such as sea dike structures)
• maximum societal benefits :
+ recreational beach
+ ecology
+ landscape
• Work with nature : sedimentation of natural sand transport
• Important increase of finances for coastal defence (~ factor 3 in 2050 !)
• “seaward solution”
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
The coastal landscape from the perspective of sea level rise
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
21st century :
Damages of the coastal defence caused by storm surge (erosion of dunes, damages to buildings on the coastal defence…)
“seaward solution” with sand nourishments (to grow with the sea)
3rd millenium :
managed retreat = change the functions of the land near the coastline (~ a different spatial planning)
= “landward solution” (<-> “seaward solution”)
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
SAND NOURISHMENT, example :
De Haan
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
SAND NOURISHMENT, example :
Oostende
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
MANAGED RETREAT, example :
UK : nature areas in stead of farmland
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
MANAGED RETREAT, example :
COMCOAST european project
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Other type of MANAGED RETREAT :
Controled flooding areas alongside rivers,
Thereby also decreasing the water level in the river
FLANDERS HYDRAULICS RESEARCH
FLEMISH ADMINISTRATION - DEPARTEMENT OF MOBILITY AND PUBLIC WORKS
Sea level rise and its danger for the Belgian coast – ir. Toon Verwaest – 13 november 2006
Other type of MANAGED RETREAT:
Projects to create nature areas (not triggered by a coastal defence problem)
Sea inlet “slufter” (~1 ha)
near borderwith France
Increasing the “Zwin” salt marches
(~100 ha) near border with The Netherlands
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