2011 vrijling flood defence systems
TRANSCRIPT
Flood defence systems in urban areas
Prof. drs ir J.K. Vrijling dr ir B. Stalenberg Section of Hydraulic Engineering Faculty of Civil Engineering and Geosciences Delft University of Technology
Land below sea level
Developments
• climate changes
• higher discharges
• more extreme storms
• sea level rise
• sinking of soil
Nature
Developments
•climate changes
•higher discharges
•more extreme storms
•sea level rise
•sinking of soil
• larger population → higher density
• more companies
• more infrastructure
result: higher value of the area
Nature Civilisation
Developments
• climate changes
• higher discharges
• more extreme storms
• sea level rise
• sinking of soil
• larger population → higher density
• more companies
• more infrastructure
result: higher value of the area
Nature Civilisation
Current tendency
increasing risk aversion
Flood protection
• strengthening of the flood defences
• reducing the loads
• strengthening of the sea defences
• reducing the loads → difficult
River Sea
Reducing the loads
• closing the estuary
• lowering of the floodplain
• deepening of the riverbed
• lowering of the groyne
• dike realignment
• flood way alias green river
• side channel
• retention areas
Outside the dike Inside the dike
Historical development in the Netherlands
Dike cross section
• Sea dike
• High waves
• Short duration
• Salt water (no grass cover)
• Estuary dike
• River dike
• Small waves
• Long duration
• Fresh water (grass cover)
Dike cross section sea dike
Sub-soil
1:6 or 8 1:3
Grass cover revetment
core Clay layer
Dike cross section estuary dike
Sub-soil
1:6 1:3
Grass cover revetment
core Clay layer
Dike cross section river dike
Sub-soil
1:2 1:3 1:4
Grass cover
core
Clay layer
Dike cross sections
• Relation dike design and failure mechanisms
Failure- mechanisms
Damming estuaries
“River” dam
System:
• Dam
• Discharge sluice
• Shipping lock
Function: • Prevent flooding by storm surges
• Shorten Coastline
• Limit salt intrusion
• Preserve fresh water
• Discharge river flow
• Let shipping pass
Many instances: • 1270 Amster dam
• 1240 Rotter dam
• 1248 Spaarn dam Zwammer dam
• ~ 1300 Monnicken dam
• ~ 1300 E dam Alblasser dam
• 1258 Schie dam
1916
Enclosure dike Zuiderzee 75 years old
Enkhuizen
Floodwalls on the quay
Delta Project 1960
Storm surge barrier Eastern Scheldt
System:
• Dams
• Storm surge barrier
• Shipping lock
Function: • Prevent flooding
• Preserve environment (nature and culture)
• Preserve shell fish industry
• Let shipping pass
• Road connection
“Closed and open at the same time”
Opening ceremony 1986 & functioning
Zierikzee
Damming the lauwerszee
• Recreational park
• Port cities restored
Cardiff Bay Barrage system
Cardiff Bay mudflats before the barrage was built
Cardiff Bay Barrage system
Trends in functions
• Flood protection
• Land reclamation
• Fresh water preservation
• Facilitate shipping
• Protect environment:
• Create environment:
• Create amenity
Damming Rijnmond
• Taming water in Rijnmond
• Safety and urban waterfront development
Waterfront Dordrecht
Utrecht on de Old Rhine
Open/gesloten Rijnmond Beweegbare kering
Waterslot
Flood defences
• specific dimensions: height and width
• location
• costs
examples: dikes, quay walls
Characteristics
Strengthening
• heightening
• widening
Urban flood defence
Green river
Green river
l
Q0
Q1
Q0
Q
Q
he1h0
x0
x
Green river: adaptation length
l
Q0
Q1
Q0
Q
Qh
hhe1
h0
x0
x
Green river: sedimentation
l
Qgr,t=0hgr,t=0
hgr,t>0 Qgr,t>0
l
A green river becomes less effective in time
Current issue
reducing the loads strengthening of the flood defences
limited space
nature development only losses ?
Multi-functional flood defences
• safety
• maintenance
• property rights
• surroundings
reckon with
future strengthening
• technical issues
• legal issues
Simple examples of multiple use
• Automatic floating wall (Kampen)
• Houses built in flood defence (Dordrecht)
• Westkeetshaven (Zwijndrecht)
Automatic floating wall (Kampen)
Houses in flood defence (Dordrecht)
Westkeetshaven (Zwijndrecht)
Possibilities of multiple use
SSL
SWL
houses
offices
shops
restaurants/cafes
traffic road
parking
promenade
city park
Possibilities of multi use
SSL
SWL
traffic road
parking
shops promenadepromenade
houses
Sea defence
Possibilities of multi use De Muralt muur
SSL
SWL
Possibilities of multi use
SSL
SWL
houses
offices
shops
restaurants/cafes
traffic road
parking
promenade
city parkSSL
SWL
Possibilities of multi use
houses
restaurants/cafes
parking
SSL
SWL
Conquering the sea again
• Completed plan “IJmuiden”
• Plan “Waterman” et al.
• Plan “New Venice”
Plan “IJmuiden”
Plan “Waterman et al.”
Venice
Venice city in a shallow sea
Plan “New Venice”