Rutger de Graaf has been awarded the title of doctor in Civil Enigineering, cum laude, for a broad study on inovations in urban water management to reduce the vulnerability of cities.
Not only shows he which inovations contribute to sustainable cities by reducing the vulnerability to flooding (and in some cases droughts), he also examines which factors contribute to (and sometimes hinder) the application of these inovations.
Here you can read chapter 6 of the thesis: Case study Netherlands: Using surface water for urbanisation.

6 Case study Netherlands: Using the surface water for urbanisation

6.1 Introduction

This chapter is about the use of surface water for urbanisation, or floating urbanisation. Floating urbanisation has recently received much attention of researchers, politicians and media. It is a flexible and reversible mode of urbanisation and therefore responds to the societal objective to increase the capacity to adapt the built environment to climate change. This innovation is expected to reduce vulnerability of urban areas by reducing flood impact. In addition, the lack of space in lowland delta areas could be addressed by multifunctional use of space combining water storage and housing by floating, or amphibious, urbanisation.

The focus of this chapter is not testing the technical feasibility in a case study. The technical feasibility is shown by describing finished projects. Instead, this chapter is an exploration study how in the Netherlands, floating urbanisation is developing from a niche market of houseboats, to a more developed industry that works on integrated urbanisation plans. As such, this chapter aims to contribute to the development of insight in mechanisms that influence the diffusion of technical concepts. The observations in this chapter are based on reviewing the literature on floating urbanisation, and the personal experience of the author in floating urbanisation projects as reflective practitioner. The mechanisms that are described in this chapter will be further tested and grounded in part 2 of this thesis.

An integrated concept that combines the three innovations of this thesis, local water supply, local energy supply and floating urbanisation will be presented. The potential of floating urbanisation to reduce vulnerability is discussed. A number of follow up projects emerged from research activities in the Transition SUW projects. It is discussed how these findings were translated to practice.

6.1.1 Background

The urban population is expected to double from 2 billion to 4 billion in the next 30 to 35 years. For the first time in history, the proportion of people living in cities is equal to the rural population on a global scale (UNFPA, 2007). More than 200,000 people move to cities every day (UNFPA, 2007). Urbanisation predominantly takes place in coastal and river plains that are exposed to flood risks. In 2003, 23% of the world population lived within 100 kilometres of the coast (Small and Nichols, 2003). In 2030, this percentage is expected to increase up to 50% (Adger et al., 2005). Climate change and sea level rise, described in chapter 2, will further increase the vulnerability of delta areas. Flood damage increased significantly over the past decades and will be increasing further due to climate change and urbanisation (Kron, 2005). In literature, various examples have been described to improve the climate robustness of cities with regard to droughts, heat stress and flooding. For instance, Van de Ven et al. (2008) have identified 150 measures that reduce the vulnerability of urban areas. With regard to flood proof urbanisation, these measures include wetproofing and dryproofing of buildings and infrastructure, building on mounds, building on stilts, constructing a higher freeboard between road level and floor level, flexible and removable constructions, amphibious housing and floating urbanisation.

6.1.2 Living on water, a niche market

The publication Mooring Site Amsterdam (Kloos and De Korte, 2007) describes the history of living on water in the Netherlands, in particular in Amsterdam. Paintings and laws in the municipal archives show that already in the 17th century there were houseboats. In the following centuries houseboats remained an important element of the water city. Housing shortage after the two world wars increased the number of houseboats to an estimated number of 10,000 at the end of the 20th century. Authorities have always struggled to regulate these ‘pioneers’ on the water. Even today, it remains unclear which spatial planning regulation apply to houseboats, notwithstanding all the policy documents that have been produced to provide more clarity (Kloos and De Korte, 2007).

Over the last decade, there has been a new development: the rising popularity of the floating house. Contrary to the houseboat which is usually a boat that is reconstructed as a place to live in, this is an ordinary house that is constructed on a floating foundation. This housing type is included and regulated in the spatial development plans of the municipality. The following parts of this chapter, describes how floating houses are entering the mainstream construction industry and mainstream urbanisation practice in the Netherlands.

6.2 Mainstreaming of floating urbanisation

This section describes policy changes, financial aspects and legislation, technical development, planning and design, the development of a commercial market, current obstacles, a knowledge agenda and demonstration projects.

6.2.1 National policy

In the Netherlands, there has been a change in perception on water management. Van der Brugge et al. (2005) describe how over the past decades, water management approach has changed from a technical approach to a more integrative approach. River flooding in the mid 90’s and pluvial flooding at the end of 90’s led to the establishment of a new government policy, ‘dealing differently with water’ (Tielrooij, 2000). Water retention increased in importance and there was a shift in approach from ‘fighting the water’ to ‘living with water’. The research program Living with Water, of which this thesis is part, is a direct result of this new approach. The societal priority to create more storage capacity led to large projects. Examples are the Room for the Rivers project and the National Water Agreement. This agreement presents ambitious targets for water storage: 425 million m¬3 of additional water storage in the period to 2050 (NBW, 2003). According to the agreement an area of 690 km2 should be made available for water storage. To give an indication, the largest lake in the Netherlands, the IJsselmeer has a surface area of 1100 km2. Due to scarcity of space, high prices of land, and competing land use functions, these targets will be hard to realise. In the densely populated Dutch delta, floating urbanisation is proposed as a viable way to realise water retention objectives while obtaining economic benefits from urban development.

Floating urbanisation is encouraged by the national government. The Ministry of Spatial Planning has designated a 15 areas for innovative housing experiments (VROM, 2005), the so called EMAB locations. In these areas, constructing houses in the floodplain is allowed if innovative building methods are applied. Furthermore, the project should increase the spatial quality of the area and additional space for water should be integrated in the project. At the first National Congress on Floating Houses in 2008, the minister of Spatial Planning and Housing proclaimed that there should be more space for living on water. In the Strategic Knowledge Agenda Water and Mobility of the Ministry of Transportation, Public Works and Water Management (Ministerie van Verkeer en Waterstaat, 2008a) floating urbanisation is mentioned as one of the key areas for further knowledge development. In December 2008, the National Water plan designated 1100 ha of national water in the IJmeer/Markermeer for water based urban development by the national government (Ministerie van Verkeer en Waterstaat, 2008b). This area will be handed over to the municipalities of Amsterdam, Almere and Lelystad. The availability of space for water based urbanisation will be a driver to develop plans for floating urbanisation.

Figure 6.1 Floating houses in Leidsche Rijn, Utrecht (source: Wenneke Lindemans)

6.2.2 Financial aspects and legislation

There has been a debate on the juridical and financial status of floating houses. Depending on this status they are regarded as boats or houses. Vice-minister Remkes proclaimed in 2000 that floating houses are regulated by land based construction legislation and housing legislation. Also the Council of State is clear about the juridical status. Based on jurisprudence, floating houses have the juridical status of a house if:’ there is an intention to stay on a certain location and the construction is connected to the underground with a mooring construction’ (Vermande, 2009, translation RdG).

The juridical status of the house has consequences for mortgages, insurance and building permits. Currently, there are commercial banks and mortgage firms that sell mortgages and insurances for floating houses in the Netherlands. This has probably contributed to market demand and trust among potential house buyers. Floating houses require an ordinary building permit and should fulfil standards in the construction legislation. The consultancy firm PRC in the Netherlands has started to interpret the construction legislation specifically for floating houses into a new guideline for developers and constructors (Vermande, 2009). This guideline includes technical topics such as: buoyancy, stability, wave movement, freeboard, tilting, safety for collision with ships, fire safety and emergency exits. The Steering Group Experimental Housing has given an advice to the minister of spatial planning to strive for complete juridical equality between floating houses (SEV, 2008). The steering group also advices to develop technical guidelines and standards to further contribute to mainstreaming of floating constructions into the construction industry. In Canada, such guidelines already have been developed. For instance the Office of Housing and Construction Standards of British Columbia provides guidelines on technical requirements, utilities, fire protection and maintenance. These guidelines are used by constructors to build floating houses and by authorities to approve development plans. Recently, the Netherlands Normalisation Institute (NEN) has started to develop standards for the floating housing industry.

6.2.3 Technical developments

In the Netherlands, most floating houses are constructed on a hollow concrete foundation. The oldest known floating house in the Netherlands that still exists was constructed in 1922 on such a foundation (Spruyt Arkenbouw, 2006). This system is relatively cheap and technically robust. Concrete segments can be connected to realise large platforms. The largest building in the Netherlands that was built on this type of platform is a prison in Zaandam. The floating foundation is 100 meters long and 22 meter wide. Disadvantages of this system are the required depth which is usually about 1.5 meters for a single house. The surface water in Dutch polders is generally shallow, about 1 to 1.5 meters. Therefore, the application remains limited to regional surface waters, lakes and canals.

In 1999, Construction Group Ooms imported a Canadian system to the Dutch market. This system is based on a core of polystyrene foam and a concrete shell. The polystyrene decreases the density of the floating construction which provides higher buoyancy. Advantages of this system are a lower required depth of the surface water. In addition the system is unsinkable and enables the construction of larger platforms. The system is more suitable for shallow surface water. A depth of 1.5 meter can be sufficient. However, the material costs are higher than the concrete system.

Another polystyrene concrete system was developed by contractor Dura Vermeer and polystyrene manufacturer Unidek. This system (Flexbase) is based on polystyrene blocks on which concrete is poured to form the ground floor of a floating building. This system was applied as a pilot in a floating greenhouse in Naaldwijk in 2005. The system is constructed on the water. There is no limitation resulting from a construction dock. The system therefore offers more degrees of freedom with regard to form and size.

Next to floating houses, the floating structure technology can be applied in amphibious housing. In particular in floodplains and emergency water retention basins, this construction method can be applied. During normal operation the house is located on a concrete foundation structure. During flooding however, the construction will start to float because of the floating foundation floor and the mooring construction that keeps the house on the location. An example of amphibious housing project in the Netherlands is Maasbommel where 32 amphibious houses have been constructed.

Weak soils are a large potential field of application of floating structure technology and lightweight constructions. In the western part of Netherlands, constructions are placed on pile foundations due to the low carrying capacity of the clay and peat soils. In addition, building site preparation by integral or partial sand fill is generally applied to make lowland areas suitable for urbanisation. This results in continuous land subsidence which causes high costs for maintenance of the public space and infrastructure. Lightweight constructions and infrastructure can make pile foundations and traditional building site preparation in delta areas obsolete. Research institute Deltares has started to do research on subsidence free cities (Van de Ven, 2009).

Besides floating housing, infrastructure on the water has been developed. In the Netherlands, the first step to develop floating infrastructure was made in 1999 when the Ministry of Transport, Public Works and Water management started to develop a pilot floating road in the project ‘Roads to the Future.’ The objective of the floating road is to deal with traffic congestion in a flexible way in areas with poor soil conditions or fluctuating water levels. Another objective is to contribute to the multifunctional use of space (Ministerie van Verkeer en Waterstaat, 2004). The design and realisation was done by a consortium of Bayards Aliminium Construction, DHV, TNO and XX architects. The construction consists of aluminium segments of 3.5 meters long and 8 meters wide that are filled with polystyrene to make the construction unsinkable. The prototype floating road was realised in 2003 near Den Bosch in the Netherlands. The road is suitable for cars with a weight of 2000 kg and a velocity of 80 km/h (TNO, 2003). In particular for temporary connections during reconstruction or renovation of tunnels and bridges, the floating road is an attractive solution (Ministerie van Verkeer en Waterstaat, 2004). It is also a promising technology for application in floating cities.

Figure 6.2 Floating road near Den Bosch (Ministerie van Verkeer en Waterstaat, 2004)

On a small scale floating gardens are constructed in the Netherlands. Inventor Robert Jasper Grootveld started to build them already in the 1960’s. The gardens are based on a system of polystyrene blocks that are tied together with fishing nets. On top of these blocks a layer of soil is placed that enables the development of vegetation, including grass, shrubs and trees. This technology enables the development of soft surfaces such as parks and gardens in floating cities.

Recent research investigates modular floating technology (Rijcken, 2003) and the possibilities of combinations of High Performance Concrete and polystyrene (Kuijper, 2006). Also high strength fibres are proposed in the floating constructions industry from the field of maritime engineering and shipyards. Although more expensive, these systems are lighter and stronger than the foundations that are currently on the market. This development potentially enables the construction of large scale projects on the water including infrastructure, access with motorised transport and public space.

6.2.4 Planning and design

There is a scale increase of planning and design from individual houses to floating neighbourhoods and floating cities. In 1999, the concept of New Arcania was presented by the Dutch engineering firm Advin as their submission in the design contest ‘water landscape of the future’. The concept consists of a vision on multifunctional use of space by floating urbanisation in a wetland area.

Planning and design of floating urbanisation is becoming more mainstream. Large municipalities in the Netherlands, such as Almere, Amsterdam and Rotterdam have included floating urbanisation in their spatial development plans (Czapiewska, 2008). Considerations to include floating urbanisation are the lack of space, the objective to stimulate innovation and the ambition to create more water storage capacity.

The idea of constructing floating cities on the sea was coined by Prof. Frits Schoute (2000) of Delft University of Technology in his retirement lecture. He introduced the philosophy of ‘ecoboats’ floating urbanisation units that are independent of fossil fuels. According to Schoute, climate change and the lack of space, energy and water in megacities will eventually lead to sustainable urbanisation on the sea.

Today, The Seasteading Institute in San Francisco is developing plans to build floating cities on the ocean. The first prototype should be realised in 2010. The mission is to ‘further the establishment and growth of permanent, autonomous ocean communities, enabling innovation with new political and social systems.’ (TSI, 2009).

Inspired by the idea of prof. Schoute, the author of this thesis, with a team of architecture and civil engineering students (DeltaSync) developed a strategic plan and design for a floating city in the IJmeer area between Amsterdam and Almere (De Graaf et al., 2006). This plan was first prize winner in the international Deltacompetion of engineering firm Royal Haskoning. The plan had the following benefits.

• A living space for thousands, reducing the need for conventional land reclamation
• A positive influence on regional ecology by large scale wetland development
• Self supporting urban development, using the water system as source of energy and local water supply
• An iconic project, further increasing tourist appeal of the IJmeer
• A demonstration project for larger floating cities
• Testing ground or accelerator for floating technology, resulting in knowledge and products that can be exported

The vision of the floating city was received positively by many organisations. It is a water management innovation that connects to many urgent regional problems such as: poor water quality and ecology of the IJmeer, mobility problems in the Almere- Amsterdam area, housing shortage, and the objective to become a knowledge based economy. The risks to start the project can be relatively small because the development can start with one building and then gradually expand while new technologies and knowledge are included in the process and the concept is gradually improved. National sustainability initiative Urgenda adopted the floating city as an icon project. TU Delft used the idea in a national campaign on high schools to attract more students.

6.2.5 Development of a commercial market

Next to 10,000 houseboats in the Netherlands, the number of floating houses remains limited. Figure 6.3 shows that until 2008, about a number of 200 floating and amphibious houses have been realised. The first project (1992) was the development of 80 floating houses in Marina Olderhuuske. Most floating houses are recreational, for instance in Maasbommel (45) and Marina Olderhuuske (80). Most of the projects are small scale and situated along the edges of rivers and lakes. In the new Amsterdam development IJburg, another 185 floating houses are realised. A large scale new project is Het Nieuwe Water in Naaldwijk with 600 floating houses.

Generally, there has been much attention from buyers for the projects that have been realised. For the first 37 water plots in Amsterdam IJburg in 2006, 381 subscriptions were received. Prizes for the plots ranged from € 116.000 tot € 142.000 (SEV, 2008). However some projects also failed, for instance due to long walking distances to parking space (Schuwer, 2007). The lack of parking space and the lack of public space are still obstacles for increase of scale. The total potential market for floating houses is estimated at 360,000 houses (Heijmans, 2006). TU Delft- OTB studied the profile of potential buyers of floating houses with a questionnaire. There were 112 respondents. Potential buyers generally have a high education, a high income, are predominantly between 25 and 50 years, and spend their free time on water recreation. A floating house is attractive for them because of the space and view on the surroundings, the living environment near the water, and because the house is designed and constructed according to their wishes (SEV, 2008). Residents in the Netherlands value a living environment next to the water. Although there are no specific numbers for floating urbanisation, the survey of Bervaes and Vreke (2004) shows that houses next to water are 8 to 16% more expensive compared to ordinary houses.

It can be concluded that floating houses is still a small luxury market. However, there is a strong market demand that could contribute to the diffusion of this mode of living to the middle and lower end of the market. This is driven by a trend toward larger scale projects, in which these segments of the housing market should also have a place. Figure 6.3 shows the steady increase of the number of floating houses in the Netherlands. Besides consumers, also entrepreneurs have discovered the market. In the Netherlands, 15 architecture firms have already designed floating houses. Four of them are specialised in this field. The number of technology start-ups is increasing. An example is DeltaSync that was founded in 2007 by the students that had won the Deltacompetition. Moreover large established construction companies are starting to focus on floating urbanisation. (Czapiewska, 2008).

6.2.6 Obstacles to further development of floating urbanisation

Despite rapid developments in the field of floating urbanisation, there are still concerns that it will remain a niche market. Many authors studies obstacles for implementation of floating houses (Fit, 2006; Schuwer, 2007; SEV, 2008; Czapiewka, 2008). These obstacles can be summarised as follows:

• Knowledge and skills
• Lack of technical knowledge among contractors and developers
• Lack of experience with floating houses among municipalities and waterboards
• Lack of public space and parking space
• Rules and legislation
• Lack of technical guidelines, standards and certification
• Uncertainty about interpretation of juridical status
• Building process
• Complexity of development processes
• Conflicting interests between water management and spatial planning
• Exploitation and economy
• Lack of trust in the development of the market
• Investment costs
• No experience in selling water plots
• Planning and design
• Lack of space to develop projects
• Accessibility for fire-fighters
• Technology
• Problems with connection to utilities
• Ecology
• Water quality impacts
• Fear of unknown risks

Most of these obstacles are not technical. Some of them are related to lack of knowledge, skills and experience with floating urbanisation. There seems to be a lack of receptivity among stakeholders. Chapter 9 and 10 will discuss this topic in detail. The lacking receptivity is unsurprising given the fact that floating urbanisation is still a niche market. In particular, local government officials who are responsible for issuing building permits are known to be reluctant to facilitate floating urbanisation. Local waterboard employees have difficulty in estimating the water quality impacts of floating urbanisation, although the potential of this innovation to create more water storage is valued by them.

Other obstacles are related to rules, legislation and planning. The lack of technical guidelines and standards makes it difficult for building contractors to construct floating houses. The interpretation of the juridical status is a perceived obstacle. Although the legislation is rather clear, there is still a lack of knowledge among stakeholders with regard to the juridical status. The complexity of the development process is mentioned as an obstacle for floating urbanisation. However, one could argue that building projects in general are complex. This is not only the case for floating housing projects.

Financial obstacles to further development of the market remain. Although many banks sell mortgages that are specifically made for floating houses, not all investors are already convinced that floating urbanisation will develop in a full grown market. This may limit the possibility to finance projects and may therefore be an obstacle for the further development of floating urbanisation. Investment costs, in particular with regard to connecting floating houses to utilities and infrastructure, remain a barrier. Construction costs of floating houses are comparable to land based houses, but connecting them to infrastructure and utilities make them more expensive. Waterboards and municipalities have no experience in the commercial exploitation of surface water for economic development, for instance by selling water plots.

The lack of public space and parking space is a problem in many realised projects. Future planning and design of floating urbanisation projects should therefore better incorporate these facilities. This is also the case for the accessibility for fire-fighters.

More research is needed to quantify the impact of large scale floating urbanisation on water quality, in particular with regard to the entry of sunlight to the watersystem. At this moment, the water quality effects of large scale projects are still unknown.

The experience there currently is with projects that have been realised, should be used optimally. Knowledge transfer of these projects to other municipalities, waterboards and contractors is needed. A learning process to fulfil other roles in the urban development process is required for floating urbanisation to go through the take off stage. A good example is the commercial exploitation of water plots by waterboards. The start of demonstration projects to build experience with this form of urbanisation and different roles could contribute to further mainstreaming.

6.2.7 Knowledge agenda

After winning the international Deltacompetition by TU Delft students, the TU Delft became increasingly interested in using the Floating City to do relevant, interdisciplinary research. The Dean of the Faculty of Civil Engineering launched an initiative to develop a knowledge agenda for the further development of floating urbanisation. A workshop was organised in March 2007 that was joined by professors from several faculties. The result was a list of main research topics that are to be studied in more detail to enable the development of floating cities. Several themes received priority by the workshop participants.

Technical themes included the development of new building materials, recycling and floating foundations. Other topics to be further investigated were: sustainable water and energy supply and accessibility of floating cities. In particular the connection to the mainland was considered important. Water quality and ecological impacts remain an area that needs to be further explored and investigated. This can be done by small scale demonstration projects including thorough water quality and ecological monitoring.

Social themes included the social acceptability of living on water, consequences for urban design, operation and maintenance, health risks and public private partnerships. The presence of public space in floating cities was regarded a key condition for realisation. In addition ecological aspects and water quality effects of floating urbanisation have to be studied in more detail, in particular in relation to European legislation. The potential contribution of floating urbanisation to the objectives of sustainable development and adapting to climate change should be investigated in more detail. Economic themes of floating urbanisation are mainly the exploitation of floating houses and the formation of public-private partnerships for floating cities. The results of this workshop were used to write a research plan for an inter faculty research group on floating cities at Delft University of Technology. This plan was finished in August 2008 and is now used to raise funding to start a research group on floating cities.

6.3 Floating Utility Units, the step to floating cities

Currently, the realised projects are still small and located along the embankments of rivers, lakes and canals. One of the reasons is that there is no integrated infrastructure that enables urbanisation on the water. To address the problems that floating projects are currently experiencing with regard to connecting to energy and water infrastructure, the Steering Group of Housing Experiments (SEV) started a project to develop Floating Utility Units. These units should provide access to a floating district and at the same time provide space for decentralised concepts of water and energy supply. As such, the units are a combination of the three technologies that are described in this thesis: local water supply (chapter 4), local energy supply (chapter 5), and floating constructions (chapter 6). Figure 6.4 shows that this unit can also be integrated with floating public space and parking space for residents.

1. Flexible connections are used to optimally enable the placement and replacement of houses.
2. Cables and pipes are integrated in the floating construction for protection and to prevent freezing. These floating constructions are also used for accessibility of the floating district.
3. Permeable pavement is applied to purify runoff before discharging it to receiving waterways. Also biofilters (10) are used to minimise runoff impacts on ecological systems.
4. Local wastewater treatment is applied based on separate collection of urine, and faeces. No pressurised connection to the main sewer system is needed. A local MBR installation can be used to achieve water quality standards.
5. A local water purification system, as described in chapter 4, can be integrated in the floating construction. Depending on the water quality of the source, nanofiltration can be applied to produce high quality drinking water.
6. The Floating Utility Units use the urban water system as a solar collector (chapter 5). Heatpumps are used to extract heat from the water system that is used to heat floating houses. In rivers, ports and lakes, the same system is used for cooling during summer.
7. Clean drinking water can be stored under water after it is locally produced. This provides an emergency storage and reduces peak demands on the production units.
8. Small scale wind turbines are used to contribute to a self supporting energy supply. A small wind turbine may fulfil 10-15% of the energy demand of a house.
9. Photovoltaic cells are used to make the floating district more self supporting. This is combined with parking spaces to enable multi functional use of space.

A Floating Utility Unit would make a scale increase possible for floating urbanisation. Although it does not make an area entirely self supporting, no external gas and water supply is required. Therefore it is an alternative for large scale networks of water and energy supply. At present, DeltaSync and SEV are forming a consortium to build the first unit as a pilot project. This would be a learning opportunity for new modes of urbanisation and self supporting urban development. The unit enables a more flexible and adaptable way of living. Houses can be sold and purchased separately. Residents can move with their house to another location. Alternatively, residents may stay on the same location, sell their house, and by a new house for their water plot (Rijcken, 2006).

Figure 6.4 Impression of a Floating Utility Unit to enable urbanisation on a larger scale (Source: DeltaSync)

6.4 Analysis

6.4.1 Technical feasibility

An increasing number of floating urbanisation project in the Netherlands and abroad demonstrate the technical feasibility. However, most of these projects are still small scale and located along the edges of lakes and rivers. These small scale settlements are still completely dependent on land based infrastructure. Technical obstacles are related to the connection with utilities, accessibility from the mainland, and creating public space on the water. Water quality and ecological impacts of floating urbanisation should be evaluated in more detail. The concept of the Floating Utility Unit that was demonstrated in this chapter could contribute to the realisation of larger projects and serve as a medium to urbanise on the water, rather than along the edges. In addition it provides a way to realise more self-supporting floating urban districts. The societal objective to realise more water retention capacity in order to adapt to climate change could become economically feasible by the revenues of urbanisation on water. Delta lowland areas all over the world face problems similar to the Netherlands. They are confronted with urbanisation, climate change and scarcity of space. In these areas, floating and amphibious urbanisation can provide an opportunity for multifunctional use of space. Although floating urbanisation is technically feasible there are also risks to this type of development. One risk is the fact that open space on the water is lost due to urbanisation. This is a potential problem in the Netherlands where open space is scarce and valuable. This risk can be handled by only allowing floating urbanisation near existing urban areas in spatial zoning plans.

Development of the market can possibly lead to the introduction of low quality floating constructions.The Netherlands Normalisation Institute (NEN) have recently started the standardisation of floating and amphibious constructions to contribute to developing the floating housing market further while assuring the quality of floating construction. Ecological impacts and water quality impacts of large scale floating urbanisation are still unknown. These impacts should be carefully monitored while floating urbanisation starts small scale. This will contribute to better knowledge with regard to water quality. The impacts should also remain limited by applying an incremental approach of urban development. Moreover, the construction of floating cities should be combined with the development of wetland areas to increase the ecological potential of delta areas. Although floating urbanisation is suitable to incorporate local concepts of water supply and energy supply, it is also possible to connect to the main infrastructure. In that case, floating cities would just be an additional pressure on nature rather than solution that improves the capacity of cities to become self supporting. This can be considered a risk. A possible way to prevent this is to impose regulation and standards to large scale urbanisation on the water.

6.4.2 Vulnerability

Floating urbanisation has the potential to contribute to reduce vulnerability of delta areas. During floods, floating constructions increase the coping capacity of an urban area. No damage to the construction will occur because floating houses will adapt to the rising water level. In addition, they may serve as emergency shelter during flooding. Because floating houses can be relocated, they are also flexible and reversible, which is a benefit to deal with uncertain future developments such as climate change. This contributes to strengthening of adaptive capacity. Floating constructions are in particular interesting for new urban areas. The potential of floating urbanisation to reduce vulnerability of existing urban areas remains limited. It is not feasible to change current urban areas into floating urban areas. The majority of future urban areas are already there. For these kinds of areas, other solutions are necessary to reduce flood vulnerability.

6.4.3 Translation to practice

Floating urbanisation is entering the mainstream construction industry and is increasingly included in urban development plans. Drivers that contribute to the increasing attention of policy makes and planners for this concept include: climate change, sustainability and rapid global urbanisation in delta lowland areas. There is a strong market demand from consumer. However, at this moment, floating urbanisation is still a small luxury consumer niche market.

Although financial and legal obstacles remain, land based construction regulations and financing arrangements are increasingly applied to floating projects. Floating urbanisation is increasingly included in official regulation. Technical developments, such as high performance floating foundations and utility units enable development of large scale water based urbanisation. Planning and design for building on water are increasing in scale.

An obstacle is the lack of receptivity of government employees that are responsible for giving permits. There is a lack of knowledge on how to judge floating urbanisation plans in the authorisation process. In addition, most building contractors have limited or no experience with floating urbanisation. This obstacle could be addressed by capacity building among stakeholders, for instance with demonstration projects that are tied to research and training programs. The knowledge agenda that was outlined in this chapter could be further developed in these programs. In addition, these programs are required for stakeholders to develop experience with fulfilling new roles in the urban development process, such as commercial exploitation of water plots by waterboards.

One of the Transitions SUW case study cities, the city of Rotterdam, has adopted floating urbanisation as an opportunity for climate adaptation and innovation. Following an invited presentation at the Shanghai World Expo Committee in July 2007, the Rotterdam project partners in the Transitions SUW project were positive about realizing a floating icon project in the Port of Rotterdam. The started a lobby within the municipality to develop critical mass for this idea. The concept was a valuable potential contribution to ongoing programs such as Rotterdam Climate Initiative, Waterplan 2 and the Knowledge for Climate research program.

In March 2008, a meeting was planned with the Transitions SUW project and the executive of the Municipal Works Department of the municipality. Following this meeting DeltaSync was commissioned by the municipality to study potential locations for a floating icon project and develop sketch designs. Three port areas came out as the best potential location. The study was finished in October 2008. The municipal board decided positively about the project. On 28 October 2008, they commissioned the municipal department to start working to develop a business case and project specification. The project should be finished in May 2010 as the Rotterdam counterpart of the Shanghai World Expo. Also the other case study cities in the Transitions SUW project showed interest in floating urbanisation. Heerhugowaard will apply the concept on a small scale in De Draai. Also Amsterdam is interested; a presentation was given to the project team of the new urban development IJburg2.

6.5 Conclusion

This chapter described how floating urbanisation is developing from a niche market of houseboats to a more developed industry that works on large scale urbanisation plans. This shift is facilitated by changes in government policy, technical developments, standardisation, and the development of a commercial market. The importance of these factors for application of new technologies is tested in chapter 10.

Influential stakeholders such as the municipality of Rotterdam, sustainability platform Urgenda and Delft University of Technology have embraced the concept of floating cities. The main technical obstacles are decentralised water and energy supply of floating cities, and the accessibility of floating cities, in particular with regard to parking space and connection to the mainland. Lacking receptivity among stakeholders remains a barrier for mainstreaming of floating urbanisation. Receptivity is further studied in chapters 9 and 10.

Risks of floating urbanisation include the loss of open space, the technical quality of floating constructions, and unknown water quality impacts. A potential way to address this problem is capacity building through well-designed, well build, and well maintained demonstration projects that are carefully monitored and evaluated. This will produce experiential knowledge among contractors, local government employees, utilities and residents.

Download the full thesis from the repository.tudelft.nl

You can also contact Rutger de Graaf by e-mail