Användning av riskbegreppet i en dagvattenkontext : En litteraturstudie om hur riskbegrepp används vid dimensionering av ledningsnät för dagvatten

Sammanfattning: Climate change and urbanization is a threat for existing stormwater networks. Many stormwater networks are designed after historical rain data that will fail to predict future events due to large changes in rainfall patterns caused by climate change and urbanization. This may lead to insufficiencies in the hydraulic capacity of stormwater networks and an increased probability of stormwater network failure that will have devastating consequences for humans, infrastructure and the environment. The aim of this study is to explore how risk considerations have been incorporated into the design of stormwater networks around the world. A document study was made to find information about the use of the risk concept and previous techniques to consider and reduce risks when designing stormwater networks. Furthermore, the study investigates the definition of risk and how to reduce risks in a stormwater context. The findings indicate that many engineers and designers rely on historical data due to the lack of updated Intensity-Duration-Frequency (IDF) curves. Updating IDF-curves takes time and can be expensive. Sometimes lack of data can even make it impossible. This highlights a challenge of and need for regular updates of data and IDF-curves to better represent current climate conditions. Furthermore, risk-based decision-making processes and different methods to reduce the consequences of floods are discussed. The conclusion underscores that there is no general method for considering risk when designing stormwater networks, different places need different methods. This study shows that there is a need of finding better ways to design sustainable stormwater networks that are safe to fail and provides insights that can guide future developments in stormwater networks.