Flood protection

The Eco-District at the Banks of the Bohrie Ostwald is structured around water with the Bohren pond, the river Ostwaldergraben and the seasonal and permanent wetlands (Ref. 2). The project covers 50 hectares and was initiated by Strasbourg Eurométropole with 2 developers: CM CIC SAREST and Nexity-Foncier Conseil (Ref. 1, 7). The district will integrate its structures into the surrounding water land and vegetation to provide for agricultural water management and flood preventing procedures (Ref. 2). It will also have green roofs, public green spaces, (Ref. 4) vegetable gardens, (Ref. 7) and composting, while on-site vegetation will participate in the deployment of green infrastructure (Ref. 5). "An eco-district of 48 hectares (17 urbanized hectares) is being created" (Ref. 11).

Since the decay of the former DDR, the lignite industry had a major downturn. Most of the mines were closed and its remaining craters re-naturalized and flooded with ground- or rainwater to be revived as recreational lakes. In the Leipzig area of "Neuseenland" up to 23 artificial lakes were created since the nineties by the respective mining company "Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft mbH" which has the obligation to securely and sustainably redevelop the area into forestry, agricultural, natural or recreational areas and reintegrate it into the adjacent landscape. The lakes have become important recreational areas for citizens (4, 8).

While Hamburg has already had an impressive green infrastructure, it is now (since 2013) implementing an interconnected green network that will cover the 40 % of its area and support commuting by bicycle, recreation and climate change resilience. The project is planned to be completed by 2034. (Reference 9) The project aims to connect the two green belts, parks, recreational areas, cemeteries and animal habitats to each other with green paths and with the already existing “green axes” leading from the agglomeration to the urban core. The green network could not only absorb more CO2 but also prevent flooding by soaking up an increased amount of rain- and seawater caused by storms. (Reference 1, 2). An extensive network of cycle paths is also being built as part of the project. (Reference 2)

Within the territory of the Region of Attica there are more than 100 wetlands including streams and their estuaries, coastal marshes and lagoons, lakes and constructed wetlands. They constitute “biodiversity islands” within a broadly degraded environment and offer the inhabitants of the Attica Region the opportunity to stay in touch with nature. A strategy and an action plan were developed for the conservation and restoration of these ecosystems in fighting climate change within the EU-funded OrientGate transnational co-operation project. (Ref. 1)
Climate Change is expected to put additional pressure on these habitats as, based on future climate projections, Attica’s vulnerability to drought is expected to rise from low to moderate by the year 2100. Drought episodes are expected to last longer and occur more frequently than in the past. This phenomenon is expected to have a serious impact on Attica wetlands as most of them are rain-fed. (Ref. 1)

In 2014, the Marseille Provence Métropole Urban Community commissioned five new stormwater retention basins in order to preserve the quality of coastal waters and reduce the risk of flooding (Ref. 4). In the past, in the event of severe thunderstorms the sewage networks became saturated and a portion of the water was then directly discharged into the sea without going through the sewage treatment plants (Ref. 1). This is seen as "one of the most important documents of recent years in terms of environmental protection. It foresees in the next 5 years, 185 million euros of major works" (Ref. 1).

The scheme was designed to manage surface water runoff from a 1 in 30 year event and to always intercept and treat the, often more polluted, first flush of highway runoff (ref. 1). A total of 21 linear rain gardens (total of 148m2) were constructed within the grass verge, allowing for the constraints of access, below-ground services, street furniture and trees. The rain gardens utilise a combination of clean stone aggregate and proprietary units to create void space beneath a planted topsoil layer. They were designed to capture runoff from 5500 m2 of highway from a total surface area of 7100 m2 (ref. 1).

“Nottinghamshire Wildlife Trust (NWT) in partnership with Nottingham City Council (NCC) proposed enhancements to the Fairham Brook nature reserve to allow areas to be re-wetted, restoring areas to their former state. The Fairham Brook watercourse within the reserve was deepened in the 1970s to improve its drainage function for the adjoining agricultural land but it had the effect of draining the reserve also, which is one of the few areas of fen habitat remaining in Nottinghamshire. Fen is a Nottinghamshire Biodiversity Action Plan priority habitat and all efforts were to be made to protect and restore the areas that are remaining. Lowland Fen was also a UK Biodiversity Action Plan priority habitat (ref. 1).

Kronsberg was built as a model district of sustainable urban development for the EXPO 2000, which motto was 'Humankind-Nature-Technology'. In the previously intensively farmed area, 3200 new dwelling unit was built. Among other sustainable technologies, the planners of the district developed a quasi-natural drainage system that aimed to provide the municipalities a sustainable alternative for traditional drainage (Reference 1, 2).

20 years after planning started in 1992, EXPO district of Kronsberg has proven its viability in terms of sustainable urban development and provided important foundations for advanced urban planning of new buildings in Hannover and elsewhere. The project was showcased in the ‘Crystal’ exhibition pavilion in London as a global standard for integrated construction. The ‘World Cities Summit 2012’ in Singapore also paid tribute to the residential area as one of the world’s hundred most innovative infrastructure projects (Reference 1, 2013).

Due to human interventions into the natural river flow with dykes, drainage of agricultural and grassland or cutting off its water bodies, the wetland Elster-Luppe had lost its groundwater base which decreased its biodiversity. With the support of the regional biodiversity fund and building on previous efforts, the city of Leipzig, together with partners such as the NABU Sachsen and research institutions, has revitalized, renaturalized and connected the water bodies of Leipzig's North-Western wetlands to one continuous watercourse since 2012. Its objective is restoring its ecosystem functions and increasing awareness for the importance of wetlands (4, 5).

The development of the sustainable district of the Haute Deûle River Banks, associated to Euratechnologies TIC center, leans on recognition of water as an element of its foundation. The current innovation is about the water garden. It is a part of the bigger project, building an eco-district on the banks of the Haute Deule river. The water garden, which plays the role of storage (stormwater) and of phytoremediator, evolves with the rhythm of rain and becomes the emblematic place for this work with water. Its vegetation improves every year and the natural seeds of young willow trees contribute to the establishment of a dynamic ecosystem (Ref 1).