Cities around the world are being impacted by more frequent and severe weather-events. With global urban populations increasing rapidly, and cities encroaching into natural watersheds, more people and infrastructure will be in harms way in the decades to come. To reduce risks to human life, property and infrastructure from climate change extreme-weather events cities need to embed resilience-thinking into current and future infrastructure decisions and investments as urban infrastructure and systems are critical in simultaneously accommodating urban growth and climate change impacts. One city that is doing so is Hamburg, Germany.
Hamburg’s resilience plan: RISA
The City of Hamburg has a growing population and is becoming more denser each year: around 6,000 new flats are constructed per year increasing the city’s sealed surface area by 60 hectares per annum. With increased surface areas and heavier storm events from climate change, more people and infrastructure are at risk of flooding in Hamburg each year. To reduce risks of urban flooding the Ministry of Urban Development and Environment, in partnership with Hamburg Wasser, has launched RISA (Rain InfraStructure Adaptation) for the purpose of developing sustainable adaptation solutions for flood protection, inland flood control and water body conservation. The aim of RISA is to create a decentralised stormwater management system for Hamburg utilising buildings, green spaces and water bodies, parking areas, streets and places to manage stormwater.
At the technical level, RISA is implementing pilot projects throughout the City including buildings that will channel water into ponds that allow infiltration, purification and retention of rainwater, carparks that collect, retain, purify and then discharge rainwater and the use of green multifunction spaces including plazas to channel rainwater from adjacent buildings and surface runoff into ponds for purification. At the administrative level the project integrates stormwater management into urban and regional planning through joint municipal interdisciplinary teams involving spatial planners, traffic planners, urban drainage planners and civil engineers. RISA also involves the holistic communication of information and education to all relevant stakeholders (citizens, municipal officials, operating companies for drainage and water body, engineering and consulting companies and universities etc.). The results of the project will support the development of a structural stormwater plan that will provide guidance for administrations, experts and property owners for the implementation of new stormwater management systems throughout Hamburg.
To increase resilience to urban flooding, cities can integrate stormwater management systems into city-wide plans.