Using the multiple scenario approach for envisioning plausible futures in long-term planning and management of the urban water pipe systems

Water utilities are facing the challenging problem of planning rehabilitation and renewal of their urban water systems for an uncertain future, which will be affected by climate change, demographic changes and extensive changes in the way the public perceives the water services. For the purpose of envisioning the future, the multiple scenario approach is presented, and its benefits and drawbacks are discussed in relation to other futures forecasting methods. The paper guides the reader on how to build scenarios that represent plausible futures for renewal planning of urban water and wastewater networks. For this purpose, a table is produced that gives an overview of relevant scenarios and their potential consequences. In the end, a case study from a Norwegian perspective is presented that gives the reader an overview of the process of building scenarios based on both qualitative and quantitative approaches.