Kostnads- nyttoanalys av införandet av hållbar dagvattenhantering som riskreducerande åtgärd mot översvämning – med fokus på monetär värdering av ekosystemtjänster / Cost-benefit analysis of sustainable drainage system as flood risk reduction measure in urban areas – Focusing on monetary valuation of ecosystem services
In this study a cost-benefit analysis (CBA) of a sustainable drainage system (SuDS) as a risk reduction measure is performed. The case is applied on the flood prone area Söderkulla in Malmö, where the focus of the study is quantification and valuation of the expected increase in ecosystem services as a result of the SuDS. Based on an estimated amount of storm water needed to be handled in the area, a set of open storm water solutions and drainage solutions are suggested. The cost-aspect of the analysis is based on the investment and operative cost of these solutions throughout the technical life of the system. The benefit aspect constitutes of the ecosystem services which the system is expected to provide every year, in terms of flood risk reduction, water and air purification properties, noise reduction, climate regulation and increase of recreational values. The value of flood risk reduction is partially based on site-specific data and partially on national historical observations from floods. The other ecosystem services are valuated though classical economical valuation methods, traditionally used for valuation of aspects without a natural market.