2. Fall and rise of urban rivers and lakes

2.1              Importance of rivers and lakes in European cities

Almost all cities around the world were built along waterways, or along a coast of an ocean, sea or lake. The multifaceted relationships between urban planning and water have structured and influenced the development of metropolitan areas, cities, towns, rural areas, villages, and even neighbourhoods throughout history and will continue to do so (Brandeis et al. (2014)).

Over time, the settling of humans next to rivers and lakes has transformed the natural environment into the towns and cities we see today. Urbanisation has come at a cost to rivers and lakes, as they have been heavily degraded to enable development, carry waste, supply drinking water and facilitate transport and industry.

In Europe, almost all capital cities have at least one major river or lake crossing their urban landscape (see Table 2). The largest rivers of Europe such as the Danube, the Rhine and the Elbe are home to a number of cities on their main channels, their tributaries of the wider catchment and on their estuaries.

Table 2. Major rivers and lakes of the capitals of the 33 EEA member countries.

Some of the most popular tourist city destinations in Europe are built on and strongly defined by their rivers, among others Paris on the River Seine, Rome on the Tiber, Budapest and Vienna on the Danube, Prague on the Vltava and London on the Thames. Some European cities, such as Dublin, are characterised by a complex water landscape unknown to most visitors passing through (see box below).

In addition to the larger better known urban rivers, there are many small rivers and streams which have shaped the landscape of European cities and are frequently subject to recent urban restoration schemes. Several of these smaller rivers and streams feature as case studies in the Annex to this report.

Lakes are not as frequent a feature as rivers in large European cities. However, there are a number of cities, which have partly developed on lake shores, coasts and estuaries, that serve as popular recreational areas and/or sources of drinking freshwater for the city. Some examples of cities with major lakes are Tallinn (Lake Ülemiste), Berlin (lakes Wannsee, Müggelsee, Tegeler), Stockholm (lake Mälaren), Zürich (Lake Zürich) and London (Serpentine Lake). Several other European capitals such as Oslo, Vilnius and Bucharest are connected to a number of smaller and middle-sized lakes.

2.2              Key impacts of urbanisation

In industrialised and developing countries in the 19^th and 20th century, most urban rivers were channelled into canals, buried or otherwise confined. Eden and Tunstall (2006) summarise the traditional European approach to urban river management as “…bury them, turn them into canals, line them with concrete and build upon the (now protected) floodplains”. This approach was designed both to improve urban hygiene and to protect cities from flooding. In the 1950s, the growing use of cars in cities led to river banks being transformed into high-speed traffic lanes (e.g. the case of the River Manzanares in Madrid and the Seine in Paris). Due to pollution from wastewater and the fact that river banks became increasingly difficult to access, traditional uses of urban rivers (bathing, boating, fishing) disappeared. Cities gradually turned their backs on the rivers that they once relied upon for their prosperity. Only major water shortages and flooding reminded local authorities and residents of the presence (or absence) of water in the city (Bruhn, 2015).

The negative impact of urbanisation on river and lake systems in European cities is wide-ranging and multi-faceted. The impacts go beyond the historical issue of water pollution and extend to structural changes of the once-more natural rivers and lakes. The ways urbanisation has affected urban rivers and lakes include (based on ECRR, 2015):

• Water quantity impacts: Decreased flow and reduced groundwater levels through abstraction as well as increased flow from surface run-off, increased frequency of floods and reduced infiltration affect the quantitative status of rivers and lakes in cities.
• Water quality impacts: Wastewater discharges and increased run-off from impervious surfaces such as roads, roofs and gardens, and contamination from household and industrial stormwater overflows degrade water quality.
• Physical structure impacts: Artificial walls replace natural river banks, barriers disrupt connectivity or in many cases the river is hidden underground (covered rivers).
• Geomorphological impacts: Urban rivers lack the space to erode their banks and deposit sediment or connect to their floodplain, which leads to altered morphology. Bridges, pipes and other infrastructure alter the width and depth of rivers, and their courses are changed by straightening and bypassing.
• Impacts on the ability to support wildlife: Natural corridors, riparian zones and in-channel habitats are lost.
• Removal of riparian vegetation: This reduces organic input, habitat complexity, increases river temperature and reduces bank stability.
• Invasive species: Urban areas often suffer from introduced non-native species that become dominant and cause damage to the environment.

Urbanisation also has a notable impact on channel ecology, made obvious in terms of decrease in biotic richness and increased dominance of pollution- and flow-tolerant species. As urban centres have expanded in size and number, negative impacts on freshwater ecosystems have become more severe and widespread (summarised by Everard & Moggridge (2011)).

The illustrations below show some examples of degraded urban water bodies:

Photos: @E.Kampa (upper left), @Flemish Environment Agency (upper right), @ Syndicat d'Aménagement et de Gestion de l'Yzeron, du Ratier et du Charbonnières (lower left), @ Wasserwirtschaftsamt München (lower right).

2.3              Re-discovering rivers and lakes in our cities

Historically, rivers and lakes offered a popular setting for urban development due to the fact that they could provide food, water, power generation, flat land for development, trade routes and transport. Furthermore, urban rivers and lakes have functioned for centuries as receivers and transporters of household and industrial wastewater, which gradually led to their degradation, making them a source of nuisance to city inhabitants. During the 20th century, many European rivers and lakes were polluted, deteriorated, and they lost their significant roles.

Since the 1970s, substantial investments have been made in sewers, wastewater treatment and stormwater management and led to water quality improvements across Europe. As a result, European rivers and lakes have gained a more positive image in cities and towns. It is now recognised that urban rivers and lakes are called upon to fulfil more roles such as providing space for recreation and an aesthetically pleasing environment for urban regeneration. More and more cities and communities re-discover their rivers, streams and lakes as open spaces in the urban environment, and as meeting points for social and cultural activities.

As cities are changing the way they view their water bodies, there are more opportunities for restoring urban rivers and lakes. Cities rediscover the value of rivers and lakes around which they were originally organised and developed and, in this context, many municipalities launch restoration projects. Especially urban rivers are becoming an important focus for restoration, and this is likely to expand further as urban development continues and demands for a sustainable and enhanced quality of life increase.

Restoration projects offer the chance for a future oriented city planning and development. In recent years more and more people have been recognizing this as an asset for their quality of life. In practice, many restoration projects for urban rivers are initiated not so much with the view to improving aquatic biotic ecosystems but as part of urban (regeneration) projects closely associated with the rivers running through the cities (Bruhn, 2015). Indeed, much of the impetus for urban restoration efforts has been the recognition of the range of public benefits that river restoration provides (Petts et al. 2002).

The type of benefits which can be delivered by improving urban water environments include:

i)                    reducing flood risk and helping to deliver flood risk management planning,

ii)                  creating opportunities to access the natural environment, providing new open spaces for amenity and recreation, and green networks for wildlife and people;

iii)                reducing the heat island effect;

iv)                reducing urban water pollution by incorporating sustainable drainage schemes and remediating contaminated land and

v)                  improving fish passage and in-stream and riparian habitats.

Delivering these benefits can have wider socio-economic consequences as restored urban water bodies create an attractive environment which encourages recreation, boost physical and mental health, encourage business investment and tourism and enhance property values. This contributes to green infrastructure, local biodiversity action plans, wellbeing and regeneration goals (Natural Scotland – Scottish Government (2015)). In addition, defining benefits more accurately (both direct and indirect benefits in terms of ecosystem services) often supports decision-making for restoration projects in cities.

Many restoration measures taken (e.g. reopening covered rivers, water quality improvements that enable bathing) have resulted in significant changes in the way citizens and visitors experience the blue elements of cities (rivers and lakes). Waterfront amenities are more and more highly appreciated and urban river and lake restorations can be a good way for improving accessibility to water.

The case studies reviewed in the Annex to this report provide evidence of how restoration of rivers and lakes in European cities can contribute to better quality of life and urban regeneration.

2.4              European policy impetus

In the European Union, a number of legislative and policy processes have provided further impetus to manage urban rivers and lakes in a more integrated way, by means of linking water quality improvements with ecosystem protection, climate change adaptation and recently with urban development.

The Urban Wastewater Treatment Directive (UWWTD) adopted already in 1991 aims at protecting the environment from the adverse effects of urban wastewater discharges and discharges from certain industrial sectors. Progress has been made in combating water pollution, especially in terms of wastewater effluents.

The Nitrates Directive also adopted in 1991 aims to prevent pollution of ground and surface waters from nitrates coming from agricultural sources. Although the Nitrates Directive is mainly relevant to agricultural activities outside urban areas, pollution from agricultural sources greatly impacts water quality in urban areas.

As public policies which exclusively focus on the fight against water pollution soon revealed their limitations, the EU adopted in 2000 the Water Framework Directive (WFD). This is the main piece of EU water legislation which reflects a turn from viewing water as a resource to viewing it as part of the environment. The WFD requires the achievement of good ecological and chemical status for all European surface waters including urban rivers and lakes. The 1^st River Basin Management Plans implementing the WFD were adopted in 2009 and updated versions of these plans are to be drawn up on the basis of a 6-year cycle (2015, 2021). Despite improved water quality in cities, there is still room for improvement in the ecological status of their rivers and lakes. Many urban rivers are still encased in concrete structures, and along with degraded habitats make environmental objectives on the basis of the WFD challenging to achieve.

Due to changes to their physical structure, urban rivers and lakes are often defined as heavily modified water bodies (HMWB), according to Art. 4 (3) of the WFD, meaning that the important human uses which they serve (e.g. flood protection and transport) should not be undermined by measures taken to improve their status. In the same time, the WFD spells out minimum requirements for the restoration and ecological quality enhancement of HMWB, including those in an urban setting.

The Floods Directive adopted in 2007 gives European countries a common framework to identify, evaluate and address flood risk. The Directive requires developing an integrated approach to managing flood risk using approaches based on the scale of the river basin and working more closely with nature. The 1^st Flood Risk Management Plans focused on prevention, protection and preparedness were to be drawn up by 2015. For cities, the Floods Directive points to the development of urban areas which are resilient to changes that would otherwise cause an increasing likelihood of flooding.

The Birds and the Habitats Directives are also relevant to urban restoration as specific restoration measures may be taken to achieve biodiversity protection objectives in urban nature reserves including freshwater habitats.

The 2013 Commission Communication on green infrastructure (European Commission, 2013b) called upon planners to use natural measures or a combination of engineered structures and natural solutions more proactively to achieve the objectives of water and adaptation policy (see EU Strategy on adaptation to climate change of 2013 (European Commission, 2013c)). River restoration in and close to urban areas is particularly relevant to green infrastructures for reducing flood risk, especially in terms of floodplain restoration measures aiming to increase natural water retention.

Further, in 2015, the Commission published the “Towards an EU Research and Innovation” policy agenda for Nature-Based Solutions & Re-Naturing Cities[1]. This agenda has provided strong impetus for a strengthened research and innovation focus and deployment of many city water-related nature-based solutions such as de-culverting of previously piped streams and the re-creation or restoration of small city lakes and ponds. These activities aim to serve a diversity of purposes of which climate adaptation is one important aspect.  

Last but not least, an Urban Agenda for the EU is now in place as a joint effort of the European Commission, Member States and European Cities Networks to strengthen the recognition of the urban dimension by European and national policy actors. The European Urban Agenda recognises that to fully exploit the potential of urban areas the urban dimension should be stronger embedded within the EU policies. To this aim, a better working method, focused on cooperation between the EU, Member States and cities is needed. Part of this new approach includes the development of a range of European partnerships (Urban Agenda for the EU, Pact of Amsterdam, 2016).

At the time of writing this report, a draft Urban Water Agenda 2030 was prepared by European cities which convened at the Cities & Water Conference (February 2016, Leeuwarden) to discuss urban priorities in relation to water. There is growing understanding among decision-makers in European cities and regions that water is as important for cities as energy or climate, and there are risks and opportunities related to water that will affect the economic development and prosperity of European cities in the future. The Urban Water Agenda 2030 calls for city leadership and coordination to address water challenges and exploit opportunities for smart and sustainable urban water management. The agenda identifies important water issues for cities, sets objectives for 2030 and proposes concrete actions to achieve these objectives around five core areas (Urban Water Agenda 2030):

-          Water efficiency – to reduce water abstraction to the level of sustainable use and good ecological status of water bodies

-          Energy and resource efficiency of urban water systems

-          Water quality – to ensure the quality of water for urban use, prevent pollution of water by cities thereby reaching good ecological status of water bodies

-          Sustainability of urban water infrastructure

-          Flood prevention and nature based solutions

2.5              City visions and strategies for water

Upscaling the new perspective on the urban water environment to enhance results

The multiplicity of aspects in which urban planning and water come together shapes the evolution of the city and its surrounding areas. While this relationship has led to the deterioration and neglect of urban water bodies in the past, more recent examples from around Europe show that the adoption of new vantage points towards city planning has the capability of changing the dynamic. In many cases this change in perspective has either arisen from or been developed into a city’s strategic vision. This can allow local officials and city planners to identify synergies across sectors and increase the level of ambition of the measures being considered. Furthermore, such city visions can help optimize actions on short term goals while keeping mid- and long term objectives in focus.

Many European cities have developed broad visions and strategies to promote a more integrated management of their water bodies, especially in terms of restoration of their rivers and lakes. Such strategies provide a broad framework for carrying out a number of restoration projects over a longer planning period. There are also important links between restoration and local/city authority strategies for open space, green infrastructure or green networks. These strategies often require a proportion of open space in developments. If well designed, this open space can create green networks for morphological restoration, wildlife and people (Natural Scotland – Scottish Government, 2015). In this context, there are opportunities to give more priority to space for the river in urban areas.

Some examples of such city strategies are the London Rivers Action Plan,  the river de-culverting strategy for the City of Oslo and the Stockholm City Water Programme(see the case studies in the Annex to this report).

Beyond developing action plans for restoring urban water bodies, several European cities (e.g. Copenhagen and Rotterdam) are developing a more water-centric overall urban design and are transiting towards a Blue-Green city model. This entails integrating water management with urban green space provision to garner the added value associated with the connection and interaction between the blue and green assets of a city (see table below). Blue-Green Cities may be key to future resilience and sustainability of urban environments and processes (Blue-Green Cities Research Project, n.d.). They aim to recreate a naturally oriented water cycle while contributing to the amenity of the city by bringing water management and green infrastructure together.

Table 3. Blue and green assets and features in the urban realm

Source: Based on Blue Green Dream, 2012.

There are also initiatives to establish so-called urban green and blue networks. The goal of urban green networks is to link natural habitats together, enabling animals and plants to move along ecological corridors connected to the city's surroundings. Urban blue networks, consisting of rivers, streams and other bodies of water in the city, can complete the green networks. The Brussels Capital Region, for instance, is strengthening the ecological corridor in the region through the development of such an urban green and blue network. To ensure a more even distribution of green nature areas and to strengthen the ecological corridor between these areas, a Regional Development Plan was drawn to gradually develop a green and blue network around Brussels. The green network connects the green areas as a ring around the urban area, and the blue network aims to improve the ecological conditions of the rivers and associated wetlands (Bruxelles Environnement – IBGE/Leefmilieu Brussel BIM, 2006). The Green and Blue Network programme was laid out in 1995 and taken up in the Brussels Regional Development Plan. New green spaces were created with “new” objectives for the urban area: preservation of natural vegetation, restoration of pond banks, recuperation of water and improvement of soil quality. Simultaneously, efforts have been made to reconnect green spaces by reopening formerly covered rivers (Chevalier, 2013).

What drives the move towards more integrated city strategies for water?

As the citizens' perception of urban rivers and lakes returns to one that acknowledges them as key historic elements of local identity and associates them with accessible refuge from the high pace of modern life in urban centres, the political narrative around urban water bodies is necessarily following course. The recognition of the multiple benefits that revitalising our urban water environments and reconnecting with them can bring to society has in numerous cases fuelled the political will necessary to transit from small scale, isolated actions to more integrated strategies based on long-term visions of better organized, more resilient cities. For instance, in the aforementioned case of Oslo, the political determination to back the city’s de-culverting strategy emerged as public and political awareness of the value of natural streams in the cityscape arose. This perception of value that was increasingly associated with the urban water ecosystems stemmed not only from recognizing that they could be used for recreational purposes, but, in the face of climate change, they also provided an increased sense of safety and resilience related to stormwater retention and cleansing capacity.

In addition to changes in local public and political awareness, policy and regulation at higher administrative scales can also be responsible for the transition towards more integrated urban development strategies, as outlined in the previous section in terms of European policy impetus (section 2.4). At the European level there is an explicit agreement on the principles upon which an ideal European city should be based as part of an EU Urban Agenda (Urban Agenda for the EU, Pact of Amsterdam, 2016). One of the characteristics put forward for the European city of tomorrow is to be “a place of green, ecological or environmental regeneration”. At EU level, it is also argued that urban territorial development should “enjoy a high level of environmental protection and quality in and around cities” (European Commission, 2011).

Finally, the environmental objectives and requirements set in place by pieces of legislation like the EU Water Framework Directive have locked in further support for integrated action, both in terms of funding and acceptability. In this specific case, the WFD’s aim for incorporating externalities by reconnecting the urban water cycle to the natural water cycle has a strong influence on policy- and decision-making at the local level. Furthermore, the Directive has provided a strategic frame that allows linking individual restoration efforts within River Basin Management Plans, facilitating communication and buy-in of stakeholders. The case of the Stockholm City Water Programme is a good portrayal of how the intrinsic relationship of a city with its water environment can converge with policy frameworks at higher scales to result in enduring commitment to water protection.

Lastly, increased pressures on urban water ecosystems are expected to result from climate change and its interaction with socio-economic factors like geopolitics, economic trends, demographic change, further urbanisation and urban sprawl, among others (EEA, 2016a). This also calls for the preparation of appropriate water management strategies in the urban context to cope with impacts and increase resilience. Such strategies should take careful consideration of the state of the environment, society and the economy at the local level (Anthonj et al., 2014) to ensure their objectives can be efficiently achieved. Furthermore, the actions planned within these strategies should go beyond addressing the direct impacts of climate change to consider the broader knock-on effects that could follow (EEA, 2016a). A good example of a city strategy taking several of these factors carefully into account is the case of the Water Plan for Rotterdam.