In 2011, Copenhagen was struck by a 1,000-year storm event, a Cloudburst, that flooded the city with three feet of water, causing over $1 billion in damage. The city engaged in a planning period to create the Cloudburst plan with the idea of Blue-Green solutions. These solutions are low-tech, on the surface, not engineered underground, and interactive. These climate adaptive solutions take place within the confines of urban space. The process followed a six-step procedure to integrate a Blue-Green approach, beginning with data gathering and investigation, modeling and mapping, a cost-of-doing-nothing scenario, a design period, community involvement, and design interaction. It concluded with a detailed socioeconomic cost-benefit analysis that tested two masterplan solutions. The masterplan variations, the conventional scenario, and the Blue-Green scenario were developed together to quantify the benefits of the adaptive scenario. The project was financed through a public-private partnership called the Copenhagen Formula, in which existing cities are retrofitted through Blue-Green solutions. Private developers invested in the government’s plan, and it gained traction for its focus not only on the areas where flooding occurs but also on upstream and upland areas where residents do not see the consequences of heavy rainfall. The plan designates a clear order of priority, in which high-risk areas, as identified in a climate adaptation plan, are addressed first, followed by areas where measures are easy to element, areas with ongoing urban development projects, and lastly, in areas where other policy directives are being followed.
Ziersen, J. J. Clauson-Kaas and J. Rasmussen. “The role of Greater Copenhagen Utility in implementing the city’s Cloudburst Management Plan.” Water Practice and Technology 12, no. 2 (2017): 338-343.