On the road to a new stormwater planning approach:from Model A to Model B

Traditional models for planning urban water systems are to great extent based on technical and economic considerations (Model A). This approach is adequate for planning isolated and well-defined water systems. With the introduction of the concept of sustainability, the water systems interact with societal processes in the urban environment. We are not any more dealing with an isolated water system but with a complex adaptive system. For such systems the traditional planning models are not good enough. A more integrated planning approach is needed (Model B). An important characteristic of this new approach is that the complexity of the planning process is not combated but made manageable. As a result, during the process different space scales are handled parallel, time plays a more important role and more actors are involved. It is an open process. Also more values of water are taken into account. Different techniques for sustainable stormwater drainage are described. Based on experiences in the city of Malmö in Sweden a practical approach for integrated planning of these types of drainage systems has evolved (Model B). As a result multiple use of stormwater facilities has today been general practice in Malmö. The outcome of some sustainable stormwater projects is presented.