2011 bianca stalenberg flood defences_kl

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multifunctional and adaptable flood defences

dr. ir. Bianca Stalenberg

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Contents

� (History of ) the Dutch river landscape

� Dutch safety policy

� Floods and countermeasures

� RPS projects on dike improvement

� Overview of flood retaining structures

� Multifunctional and Adaptable Flood Defences

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The Dutch river landscape –ancient

Already in ancient times, many people were drawn towards rivers:

� food – nourishment of crops

� food – fish / drinking water

� transportation possibilities� flood protection by living on river dunes

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The Dutch river landscape –today

Today, waterfronts are especially attractive forthe construction of luxurious houses andrecreational activities.

Water is not only our friend during sunny days,but also our enemy during stormy days.

Flood disasters happen all over the planet;every year.

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Four large rivers with estuary in the Netherlands: Ems, Scheldt, Meuse, Rhine

25 % below mean sea level

65 % will be flooded without flood protection:� 9 million people� 70 % of Gross Domestic Product

1

23

4

1 2 3 4

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Four large rivers with estuary in the Netherlands: Ems, Scheldt, Meuse, Rhine

25 % below mean sea level

65 % will be flooded without flood protection:� 9 million people� 70 % of Gross Domestic Product

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The Netherlands is a rather flat country.

Lowest point is found in the city of Rotterdam: 6.7 meters below mean sea level.

Highest point is found in north east of the Netherlands: 322.5 meters above mean sea level.

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Dutch safety policy

Until the beginning of the twentieth century dikes were improved after

every flood disaster.

This approach was changed due to severe floods of 1926 and 1953.

The Delta Commission advised to implement a new system ofprotection based on probabilities.

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An area should be protected for a flood event in which the

flood level has a certain probability of exceeding. The floodsafety level is set by the government.

Safety levels in the NetherlandsZuid-Holland/Noord-Holland: 1/10,000 per year

Zeeland/Groningen/Friesland/Flevoland: 1/4,000 per year

River landscape: 1/1,250 per year

risk = probability X consequence

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Climate change

The probability of a flood can increase due to several physicalprocesses.

Changes in temperature are expected to cause changes inprecipitation and evaporation.

More extreme events with heavy storms, downpours and snow fall, butalso extreme droughts are likely to be related to the increase of theaverage temperature.

Additionally, changes in sea level are also a well known concern.

risk = probability X consequence

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Economic development

The risk of a flood has significantly increased due to economicprocesses during the last century. This is mainly due to twodevelopments.

The first development is the increase in population in urban areas andthe increase of the economic value of urban areas.

The second development is the transformation of rural land into urbanland. This resulted in a drastic decrease of surface water that had itseffect on storm water storage.

risk = probability X consequence

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Ruimte voor de rivier

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Dike relocationNijmegen – Lent (NL)The room for the river policy creates a shift from traditional

dike improvement towards spatial measures.

Aim is to cope with an increase in discharge without an increasing water level.

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In 2008 the Commissie Veerman advised the government on the

protection of the Netherlands against the consequences of climatechange. Questions were answered about how to organise the

landscape of the Netherlands so that it:

� is climate proof for many years; � is protected against floods;

� remains an attractive country to live, work, recreate and invest in.

Recommendations

3. Developments in areas outside the dike rings must not influence the discharge capacity of the river negatively.

4. The safety in coastal zones has to be realised with artificial nourishment of sand, broadening the coast line.

10. An investigation has to be started to see if the area Rijnmond is suitable for closure on demand. This will create the possibility of combining functions like safety, fresh water storage, urban development and nature development.

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As reaction on this advice, the Dutch government launched a national water plan at the end of 2008.

The Dutch government stated that the policy on water safety should be based on risk based management.

Aim of the Dutch government was to develop a sustainable approach which was done by introducing three layers.

1. Measures for prevention of floods which was still seen as the highest priority for flood management. This layer aimed at a reduction of the flood risk by reducing the probability.

2. Sustainable spatial planning in which the threat of flooding obtained a prominent role. Taking flood risk into account in spatial planning would reduce the amount of damage and casualties of a flood.

3. Organisational measures during flood disasters. This layer aimed at a reduction of the flood risk by reducing the consequences.

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The Delta Programme of the Dutch government desires asafe and appealing Netherland, today and in the future.

This programme investigates 5 important decisions:

1. Update of safety levels; 2. development of an approach to enable sufficient fresh water; 3. a decision about the water level at IJsselmeer; 4. a decision about the protection of Rijn-Maasdelta (Rijnmond); 5. a national policy on (re)developement of urban areas.

Wim KuijkenDeltacommissaris

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storm surge pluvial floods fluvial floods

floods and countermeasures

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Storm surge

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Storm surgeMaeslantkering Rotterdam

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Pluvial floods

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Pluvial floodsParking Museumpark Rotterdam

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Fluvial floods

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Fluvial floods in urban areas

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Fluvial floodsDakpark Rotterdam

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Bergambacht-Ammerstol-Schoonhoven

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Veender- en Lijkerpolder

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storm surge pluvial floods fluvial floods

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Flood retaining structures classification system

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Earth structuresThese structures are weight structures which are naturally formed by morphologyor which are constructed with mainly earth materials.

Special water retaining structuresThese structures are used in areas where other functions are present causing insufficient space for earth structures.

Hydraulic artefactsThese structures are mainly applied at utilitarian crossings and cause gaps in the flood defence. Examples are structures for navigation andwater management.

1.

2.

3.

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Temporary structuresThese structures are only placed and used during a short period of time. They are stored elsewhere.

Permanent movable structuresThese structures are constructed at location and cannot be stored elsewhere. The structures are (partly) movable which minimizes the hinder for other activities during normal circumstances.

Permanent immovable structuresThese structures are constructed at location and cannot be stored elsewhere. They are not movable and therefore always present in the urban realm.

Combined structuresThese structures are a combination of the above mentioned structures.

a.

b.

c.

d.

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I. water - earth

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Coastal shore line, river shore line, lakes, channels, polders

Applicability

B = large, needs spaceh = according to demanded safety

levelL = flexible line element

Dimensions

Dimensions and shape of the cross section

Retaining principles

Clay or sand with turf / asphalt / block revetment

Material revetment

Clay or sandMaterial core

Specifications

dikes

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I. water - earth

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At every transition zone with enough space for piling up

Applicability

B = medium, depending on the height differenceh = according to demanded safety levelL = flexible line element

Dimensions

Dimensions and shape of cross section

Retaining principles

Bag: jute or synthetic materialFilling: sand

Material

Specifications

sand bags

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I. water - earth

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Locations with paved surface and easy access for usage

Applicability

B = mediumh = according to demanded safety levelL = flexible line element

Dimensions

Dimensions and shape of the cross section

Retaining principles

SteelMaterial

Specifications

gate flood defences

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I. water - earth

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At every transition zone with space for anchors: often applied in harbour areas

Applicability

B = very small (without earth section)h = according to demanded safety levelL = flexible line element

Dimensions

Drive depth of wall in combination with earth pressure

Retaining principles

Wall: steel (sheet pile) or concrete (e.g. slurry wall) or woodAnchor (e.g. screw anchors or grout anchors)

Material

Specifications

slender retaining walls

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At every transition zone with space: often applied in harbour areas

Applicability

B = medium width, according to demanded safety levelh = according to demanded safety levelL = flexible line element

Dimensions

Wall: weight of structure / pile foundationCut off: expansion of saturation line due to its length

Retaining principles

Concrete caisson / cofferdam / wall: concrete or bricksSubsoil foundation or pile foundationCut off

Material

Specifications

gravity dams

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At every transition zone: often applied in harbour areas

Applicability

B = medium width, according to demanded safety levelh = according to demanded safety levelL = flexible line element

Dimensions

Wall: weight of structure combined with earth and foundationCut off: expansion of saturation line due to its length

Retaining principles

Wall: concretePile foundationCut off

Material

Specifications

L-shaped walls

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I. water - earth

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In gaps caused by cross roadsIn gaps caused by buildingsIn combination with dikes and quays to gain extra height

Applicability

B = smallh = according to demanded safety levelL = flexible line element

Dimensions

Extension of the permanent structures:Drive depth of the structure in combination with earth pressure

Retaining principles

Wood (in combination with horse manure)Aluminium with rubber profiles

Material

Specifications

stop logs at cross roads

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In gaps caused by cross roadsIn gaps caused by buildingsIn combination with dikes and quays to gain extra height

Applicability

B = smallh = according to demanded safety levelL = flexible line element

Dimensions

Extension of the permanent structures:Drive depth of the structure in combination with earth pressure

Retaining principles

Wood (in combination with horse manure)Aluminium with rubber profiles

Material

Specifications

stop logs at doorways

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In gaps caused by cross roadsIn gaps caused by buildingsIn combination with dikes and quays to gain extra height

Applicability

B = smallh = according to demanded safety levelL = flexible line element

Dimensions

Extension of the permanent structures:Drive depth of the structure in combination with earth pressure

Retaining principles

Wood (in combination with horse manure)Aluminium with rubber profiles

Material

Specifications

stop logs at line elements

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II. water - water

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Sheet piles (concrete or steel) in combination with earth

Material

In areas with difference in height of water and / or earth

Applicability

B = smallh = according the demanded safety levelL = flexible line element

Dimensions

Vertical waterproof wall with enough length to provide sufficient stability

Retaining principles

Specifications

cofferdams

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II. water - water

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At transition zones of river – sea or river - lake

Applicability

B = medium / large, depending on the gateh = according to the storm level and crest of surrounding dikesL = large, depending on the canal width

Dimensions

Weight of the structure / pile foundation in combination with gates

Retaining principles

Concrete / steel / fabricMaterial

Specifications

storm surge barriers

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gate flood defences

cofferdamsquays

storm surge barriersfortification

sandbags floodproof houses

high groundsdikes

stop logs

earth dams

stairs

dams

How can synergy be realised and maintained between the technical function of flood protection and urban functions in the shared realm of an urban riverfront?

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Tokyo (Japan)

The flood wall provides sufficient protection against flood water.

The flood wall causes visual and physical hinder for the urban area directly behind the structure.

There is a conflict between urban functions and flood protection.

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Venice (Italy)

The quay provides insufficient protection against flood water.

The quay is fully integrated in the urban activities and provides an added value to the area.

The combination of urban functions and flood protection create synergy.

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Tiel (the Netherlands)

The dike provides sufficient protection against flood water.

The dike causes a physical and visual barrier for the adjacent urban areas.

There is a conflict between urban functions and flood protection.

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gate flood defences

cofferdamsquays

storm surge barriersfortification

sandbags floodproof houses

high groundsdikes

stop logs

earth dams

stairs

dams

How can synergy be realised and maintained between the technical function of flood protection and urban functions in the shared realm of an urban

riverfront?

The AFD concept

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AFD concept - multifunctional

The AFD concept aims to integrate several functions into one multifunctional structure.

The AFD concept does not hinder urban development, because the multifunctional structures are useful to flood controllers and to the public. The existing conflict between

urban functions and flood protection is decreased. The feature ‘multifunctional’ of the

AFD concept enables physical synergy in an urban riverfront.

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“Dordtse Wand” – Dordrecht (NL)

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“Westkeetshaven” – Zwijndrecht (NL)

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“HafenCity” – Hamburg (D)

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Creating physical synergy in an urban riverfront should not be a snapshot, but a sustainable affair.

The AFD concept applies to multifunctional flood defences which are adaptable.

The feature ‘adaptability of the AFD concept maintains physical synergy in an urban riverfront.

This could lead to sustainable structures which anticipate on uncertainties of for instance climate change or change in urban functions.

The AFD concept can contain three types of adaptability:

• Extension• Over capacity• Refurbishment

AFD concept - adaptable

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AFD concept – adaptable – extension

This type implies easy expansion of a multifunctional flood defense in the future by constructing a larger foundation than initially needed.

The structural redundant capacity will allow an increase in the volume of the multifunctional and adaptable structure when for instance the river discharges increases or the economic value of the hinterland increases.

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“Adaptable building” – Deventer (NL)

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AFD concept – adaptable – over capacity

This type implies oversizing so expansion or reconstruction of a multifunctional flood defense due to increasing flood discharges or due to population growth becomes unnecessary.

This is achieved by constructing urban elements with flood retaining abilities, when the dimensions of these urban elements are bigger than the initially needed dimensions for flood protection purposes.

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“Super levee” – Tokyo (J)

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AFD concept – adaptable – refurbishment

This type implies refurbishment of a multifunctional structure so that the technical lifespan can be extended without alteration in functions which applies to both urban elements and flood retaining elements.

Elements that tend to exceed their technical lifespan are replaced by taking the technological possibilities and building regulations of the future into account.

Refurbishment is purely driven by the technical performance of the structure and not by external factors such as climate change or economic changes

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Refurbishment of facade

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moving objectssuper quayurban dike

easy water water building moving building

Possible types

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No flood retaining structure can provide a 100 percent safety against floods.

They are designed according to a specific flood event of which the government has decided that this event is the upper boundary for flood safety.

Additional safety can be realized by taking damage mitigation measures.

The reliability of a flood retaining structure depends on movability.

Human error can cause failure of the flood retaining structure before the desired safety level is reached.

This is also applies to multifunctional and adaptable flood defenses.

AFD concept – technical aspects

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AFD concept – technical aspects

Can urban elements increase the technical performance of the flood retaining elements of a multifunctional flood defence?

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AFD concept – sustainability

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multifunctionalThe construction of a multifunctional flood defense is more expensive than the construction of a conventional flood defense, because it contains both flood retaining elements and urban elements.

The construction of a multifunctional flood defense could only be financially successful if it were realized by financial support of different stakeholders.

Project developers could be interested in a joint project because the presence of water could create an added value in residential areas.

Water can have a conservative added value of • 10 - 15 percent for the seashore, • 5 - 10 percent for river locations • 5 percent for lakes.

Flood events can have a negative impact of 0 - 22 percent.

AFD concept – financial aspects

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AFD concept – financial aspects

adaptableAim of the AFD concept is to provide a positive financial end result by investing more money into the flood retaining elements at the initial phase so money could be saved in the future.

The financial feasibility is at risk in case of lack of social support or financial support when future improvements of the flood retaining elements are necessary.

It is crucial not to look at purely costs, but also at the benefits!!!

The aim of the UFPM tool is to achieve that flood controllers and urban planners work

more closely together in the design process of an urban riverfront.

‘Urban Flood Protection Matrix’ tool

1. visuele hinder van de kademuur2. fysieke hinder van de kademuur3. bijdrage aan de stedelijke kwaliteit4. rivierfronten tussen rivier en kademuur5. frequentie and duur van hoogwater

score is opgebouwd uit:

QQQQQ

1. bereikbaarheid van de kademuur2. zichtbaarheid van de kademuur3. tastbaarheid van de kademuur

score is opgebouwd uit:

QQQ

1. materiaal van de kademuur2. beweegbare / tijdelijke elementen3. mechanische rotatie / plaatsing of menselijk handelen

score is opgebouwd uit:

QQQ

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Dissertation can be downloaded from: http://repository.tudelft.nl

Decision support system UFPM can be consulted at: http://www.urbanriverfronts.com

For further questions you can reach me at:

RPS advies- en ingenieursbureau bvTeam WaterkeringenElektronicaweg 22628 XG DELFTM. 06-11 599 719E. bianca.stalenberg@rps.nl

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