The AVV-project (Attention for Safety) aims to develop a Decision Support System, which is able to analyse the durability of the safety policy for the coming 15-20 years, bearing in mind the changes that take place on the long term (50-100 years). In the project new safety strategies are developed, which are able to deal with long-term in climate, soil dropping, land use and governance. The project not only looks at the coast but at the water systems on land as well. However, the biggest flood rik
is expected to happen from sea. The project looks at extreme sea level rises of +5 m (Fig. 3.27). This approach leads to unorthodox perspectives on the future.
Three questions are crucial in the research of the future safety of the Netherlands: What are the expected long-term developments, which governmental, societal and economical boundaries are relevant in case of flooding and water annoyance and what are the safety perspectives that are capable of dealing with the long-term.
Three rough perspectives for 2100 were developed during several workshops with experts (Aerts, 2007).
The first perspective is called Business as Usual, in which current techniques and practice is the standard. The dikes will be heightened, space is created for rivers and coastal suppletions are done on a regular basis, even if the rising of the sea level reaches five metres.
In the second perspective - Raising Holland - parts of the Netherlands are heightened if the sea level rise further (Kerkhof et al., 2007). All new building activities are realised at minimal 5 m above current sea level, on mega-wierden (artificial hills). Sand from the North Sea is used to do so. After this first phase of heightening the higher areas are connected with each other by long super dikes, which protect existing cities against floods. Randstad Holland can be protected with one long inhabited dike, by combining the new super dikes smartly with existing dikes (Fig. 3.28).
In the third perspective - Widening Holland - the Dutch coast is extended. The new coast is realised at higher altitudes in order to be able to live there, even if the sea level rise is five metres. Behind the broad coast the lower parts of the country still can be inhabited, while the bigger part of the population lives in the higher parts of the country (Fig. 3.29).
The perspectives are developed to include the full bandwidth of possible futures and find solutions for the entire scope of possibilities. Some solutions seem extreme,
High Land Low Land
A Perspective for the year 2100
Fig. 3.28 Scenario 2100 Raising Holland (Source: Aandacht voor Veiligheid, www.adaptation.nl)
but they are necessary to test the Decision Support System for less predictable variants. By doing so it can be guaranteed that the System functions in all situations of water annoyance or floods and can produce information on costs and spatial claims. The next step is to test the Support System in some pilot cases, in which the solutions will vary again from probable and logical to exceptional and away-from the average.
3.2.8 The Dutch 'Delta Commission'
In September 2007 the Delta commission is inaugurated. The first Delta commission was active after the Flood of 1953. The Minister of Traffic and Public Works has the
opinion that it is currently, with sea level rise and climate change, essential to look at the protection of the Dutch coast and the hinterland. The assignment for the second Delta commission, chaired by former minister Veerman, is to raise insight on the expected sea level rise and other climatic developments, which will have impact on the Dutch coast. Beside this, the commission advises on a comprehensive policy for a sustainable development of the Dutch coastal zone (Ministerie van Verkeer en Waterstaat, 2007).
The commission answers in its report (Deltacommissie, 2008) the question how the Netherlands can be protected against climate change and how the Netherlands may look like if on the very long term the country is laid out in a climate proof way. In its analysis the commission takes broad scoop. Beside protection against flooding and safeguarding the fresh water reserves, integration is sought with many different functions (working, living, recreation, nature, landscape, agriculture infrastructure
IJssel-lake area area
Fig. 3.30 Different subregions in the Dutch water system (Source: Deltacommissie, 2008)
Fig. 3.30 Different subregions in the Dutch water system (Source: Deltacommissie, 2008)
and energy). Therefore, the coast as well as the river system is subject of the report. The commission advises not only on how to deal with the effects of climate change, but aims at creating new changes and challenges also. The Deltacommission states that solutions may differ for each region and these regions are defined based on the national water system (Fig. 3.30).
The urgency to act now, while the problems become manifest on the longer term is found in several reasons (Deltacommissie, 2008):
1. Many locations along the Dutch coast do not satisfy the set standards. The standards themselves are outdated;
2. The changes in climate are developing in a rapid pace and seem to accelerate;
3. The sea level rises faster than assumed up to now. It is estimated that the sea level rise in 2100 will be 65-130 cm and in 2200 between 2 and 4 m;
4. There is an increasing change in extreme variables in river discharges. The summer discharge will be much lower as the winter extremes become much higher. In 2100 the Maas capacity needs to be maximal 4600 m3/s and this standard for the Rhine is 18,000 m3/s, much more than estimated so far.
The following problems emerge over the next century (Deltacommissie, 2008). The solving of most of these problems needs to be started in the next years.
1. Up to 2050 the sandbanks in the Wadden Sea are capable of growing with the rising sea level. If the sea level rises as predicted somewhere between 2050 and 2100 they are no longer capable to do so;
2. Up to 2050 it is possible to sluice water from the IJssel Lake into the Wadden Sea freely. Between 2050 and 2100 this is no longer possible;
3. The fresh water reserve in the IJssel Lake becomes too small to provide different parts of the country with fresh water all year by 2050 and this is becoming worse in 2100;
4. The influence of seawater in the river system increases by 2050 and is moving further upstream in 2100;
5. Flooding chances in the Maas increase by 2050 and for all rivers by 2100;
6. Pay attention to the strength and height of dikes and dunes;
7. The Delta works in South Holland and Zealand need to close more often in 2050, but are malfunctioning in 2100;
8. The inlet of freshwater in the Randstad is increasingly disrupted;
9. Increased amount of saline seepage in lower parts of the country; 10. Retention area for river water discharge is required (Fig. 3.31)
The Deltacommission developed a future vision for the Netherlands. How need the Netherlands be adjusted if is focussed on possible developments in the far future. The Netherlands stays the safest delta in the world. The country stays attractive to live work, invest and recreate in. This is safeguarded by investments in two pillars: safety and sustainability. The living conditions of today are kept and improved.
In order to make this ambition come true several objectives are formulated (Deltacommissie, 2008):
1. Efficient use of water, energy and other raw materials. The cycles of water, energy, sediment and other raw materials must be closed;
2. The layout of the country needs to be based on natural processes on location. Space is needed for the dynamic of sea and rivers and new biodiversity and landscapes are to be created, leading to adjusted living environments;
3. Energy can be produced at or near the coast in the form of wind parks, osmosis and tidal plants;
4. The Randstad Holland stays the heart of the country. The lowest parts of the Netherlands play the major role in the national income, culture and history and food production;
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Fig. 3.31 Developing problems in 2050 and 2100 onwards (Source: Deltacommissie, 2008)
5. Enough fresh water must be available;
6. Develop the country with the changes in climate and not against it. Move with natural processes gives people and nature the chance to adapt to the changes easily.
188.8.131.52 Short and Mid-Term Measures
Based on the future vision the Deltacommission defined 12 measures (Fig. 3.32), which should be implemented for the short (2050) and mid-term (2100):
1. The safety level of each dike ring in the Netherlands should be improved by a factor 10. If there are any urgent locations the concept of the Deltadike (high or broad) should be sustained. A careful look at local situations is required and solutions should be made to measure;
2. If new building activities are planned at physical un-logical places, the extra costs should be carried by the beneficiaries;
3. If the discharge capacity of the rivers can be secured, building in outer-dike areas is sustained. The owners are responsible for measures which reduce the effects of floodings;
4. In front of the North Sea coast sand needs to be supplied in order to enhance the transportation and dune forming of the sand up to the Wadden Sea. This 'sandmotor' provides the coast with enough material to extend its size;
5. Supply the Wadden Sea with material helps the wetland to grow with the sea level. After 2050 this process can no longer be guaranteed and the Wadden Sea as we know it might disappear. The kwelders of the North Netherlands coast and island polders need to be protected against sea level rise;
6. In the Southwestern Delta the Oosterschelde has a lack of tidal processes and intertidal areas are absent. On the long term both tidal processes and the forming of intertidal areas should be resolved by reintroducing tidal dynamic;
7. The Westerschelde must be kept open and function as natural as possible as an estuary. Dikes along the shore need to be strengthened;
8. In the Krammer-Volkerak-Zoommeer temporary water need to be stored. An interesting sweet-salt gradient can be developed here. If this is realised an alternative fresh water reservoir needs to made;
9. In the River area the measures in Room for the River need to be implemented quickly and by means of buying land, there need to be anticipated on the required capacity of 4600 and 18,000 m3/s;
10. In Rijnmond the 'Closable Open' principle needs to be implemented. The main discharge of river water needs to be done through the South-Western Delta and sweet water needs to be imported from the IJssel Lake. Local storage of surplus of water in deep polders;
11. The water level in the IJssel Lake (except the Marker Lake) is brought up by maximal 1.5 m in order to make free sluicing of water towards the Wadden Sea still possible. The Lake functions as the strategic fresh water reserve for Northern Netherlands, North Holland and Western Netherlands;
12. The governmental organisation needs to consist of a steering committee at the national level chaired by the Prime Minister and a delegated responsibility to the regional authorities, a National Delta foundation and a new Delta law.
The Delta commission has chosen to defend the country against high tides, from sea and rivers, for an open defensive system, because this offers a higher environmental and ecological quality and on the long term, with further rising sea levels and higher river discharges, more flexibility and perspective. Among the different solutions of large or small dike rings, heightening partially the country and broad dikes, the commission favours the introduction of so-called broad dikes at weak places in the coastal defence in the Netherlands. This solution contains several advantages (Vellinga, 2008): It decreases the number of casualties and damage, realisation is technically relatively simple, it offers more safety and it offers new planning opportunities. Main disadvantage is that this solution requires political courage. Current dikes breech if high tide reaches a level of 5 m above average. A broad dike never breaks, it just overtops with a little water annoyance as result. A broad dike can be laid out as a coastal zone, which varies from a broadened dike at current altitudes or it may be realised as a multifunctional zone, with ecological values, attractive living environments and chances for new functions (Fig. 3.33 and 3.34). In many cases it is possible to realise a wet zone behind the dike, where seawater can be let it and provides the area with unique qualities
The Deltacommission is ambitious. Fundamental changes in the National water system are proposed. The heightening of the IJssel Lake water level, the transformation of discharge routes of the big rivers and the introduction of the large increase of suppletion of sand in front of the Western coastline are major interventions, which will give the Netherlands definitely another structure. On the other hand, the commission stays with the well-known techniques from the past, like a strong belief in the technical possibilities of dikes. Higher and higher dikes need to provide a safe situation behind the dike. This is the priority and second and third strategies are literally second best options. This is, at least, the suggestion resembling from the report. Two conclusions can be drawn from this. In the first place, the structural National measures need to be transformed to local and regional planning levels. If the suggestion from the national is that the strengthening of dikes is the first priority no local authority or regional will eventually 'invent' unorthodox alternatives. Derived from this, the second conclusion might be that the advise does not really encourage people to become creative and find new solutions aiming to look at the coastal defence as a multifunctional assignment, which needs to be designed integrally. The combinations of functions such as nature, water management and living near or on top of the dike zone will be developed rarely. With a rapid and uncertain future regarding climate change, flexible and resilient solutions are required. These solutions need to be capable of functioning as coastal protection under unexpected and unpredicted conditions.
The synthesis of all the Dutch plans shows that a large number of suggestions have been made to combat risks of flooding on the mid- and the long-term. The estimates of the Delta-Commission shows that several strategic decisions can be made to substantially decrease the risks of flooding for larger or smaller parts of the country. Especially promising seem the suggestions to create broad dikes, create a sandmotor to supply the coastal zone with sediment and create efficient zone for overtopping seawater. These suggestions will provide safety for a long period and for the majority of circumstances. In case climate change worsens in the next decennia there is time enough to explore more unorthodox solutions to defend the country from flooding. Meanwhile it is important that in thinking about the coastal zone the ecological qualities are not underestimated. In supplementing the coast and minimising the efforts to keep the country safe, the ecological qualities can be developed at the same time. This is not only a matter of safety, but is also required to create an adaptive system of nature reserves and connections (see also Chapter 5). Grand views and innovative proposals need to be stimulated at the same time in order to be ready of circumstances change unexpected. A strategy in which both the short-term measures as well as the innovative chances are stimulated, the Groningen approach, is especially worth to explore, because it safeguards existing safety policies and explores new ways at the same time.
3.3 Hamburg - Hafencity 3.3.1 Masterplan
Hamburg is located in the northern part of Germany. The distance from the North Sea is about 100 km. Still, the city is under influence of tidal changes and vulnerable for storm surges and high tides. The way the city tries to deal with the coastal defence is integrated in the urban context. The approach contains two basic insights: heighten parts of vulnerable areas and realise a waterproof lay out and buildings in areas that are not heightened. In the Hafencity project these principles are used.
Next to the city centre of Hamburg an old harbour area exists. The restructuring of this area - Hafencity - makes it possible to extend the city centre towards the river Elbe. In the area historical buildings are placed in a Dockland-like environment. The area lies outside the main protective flood defence, which makes the area vulnerable for floods. Especially during high tide the narrow river causes uprising of water levels and large parts of the area are flooded every year.
The main objective of the redevelopment is to create a mixed-use area, where functions, like culture, tourism, working and living are combined [Hafencity Hamburg GmbH, 2000]. A metropolitan character arises with a maritime atmosphere, where ships and quays are visible and contact with water is secured. The
total size of the site is 100 ha and eventually 1.5 billion m2 will be realised in 5500
dwellings and 20,000 jobs, mainly in services and shopping.
As starting point for the urban planning concept (Fig. 3.35) several design principles are defined:
1. Enhance the resemblance of the history at the site;
2. Create a multifunctional and mixed-use space;
3. Create splendid water related spaces: waterfront promenades, squares and boulevards;
4. Design a hierarchical structure, where main and less important places are combined. In the urban design spaces are mixed: spectacular and non-spectacular, broad and narrow, closed and open;
5. Aim for an ecological, economical and social sustainable urban planning. A planning, which includes minimal use of energy and materials, uses renewable resources and designs long lasting urban structures;
6. Identification of the area should not only be based on rational criteria, but also on the emotional side, including art and cultural dimensions as well as spatial quality in architecture and public spaces;
7. The Hafencity needs to be connected strongly with the city centre and neighbouring city parts.
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