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Responses to urban flood risks: Links to river restoration

Increased urbanisation brings higher concentration of people, economic activities and assets, subsequently resulting in higher disaster risks (UNISDR, 2012). In terms of flood risk and resilience to flooding the importance of strategic planning and design becomes evident when reflecting upon the main causes for floods in inland urban areas described above. Design, operation and maintenance of the urban drainage network, as well as the mode and direction of the city’s expansion are all variables that can be controlled or at least influenced by strategic planning. In this context, strategies and measures to protect and restore natural areas, especially in those parts of the city at higher risk of flooding, can become key to reduce disaster risk and ultimately the impacts resulting from catastrophic flood events.

Cities can carry out a number of actions to enhance their protection against flood damage. These can include 'grey' flood protection and appropriate urban designs but also green solutions, such as providing more space for the city rivers. In urban areas where appropriate spatial planning and disaster risk reduction efforts are undertaken (for instance, sensible building codes are developed and respected, human settlements are established away from floodplains or steep slopes and infrastructure and services are suitable), the consequences of flood events and other disasters are kept to a minimum (UNISDR, 2012). Sustainable urban drainage, stormwater management and green roofs are also long-term approaches to managing surface and groundwater by reducing the rate and volume of run-off.

As part of the United Nation’s “Making Cities Resilient Campaign” the City of Venice elaborated a plan that encompassed structural and bio-geomorphological elements for flood protection. The plan includes a wide set of measures ranging from greener solutions like the reconstruction of wetlands and reclamation of polluted sites, through softer solutions like flood monitoring, early warning and public awareness raising, to more traditional interventions like city pavement elevation and urban maintenance (UNISDR, 2012). In several other European cities, flood protection measures are combined with the restoration of river banks and the redevelopment of waterfront areas to support recreation and green urban planning.

The need to address the risk of flooding has actually been one of the main triggers for restoration activities in case studies reviewed for this report. For example, persistent flooding events (often resulting in substantial financial damages) have triggered restoration activities in the urban areas of the River Waal in Nijmegen, the River Quaggy in London, the River Isar in München, the River Dyle in Leuven and the River Glinščica connected to the Podutik reservoir in Ljubljana.