Pär's Phd aims to evaluate different drainage systems based on costs and benefits of the systems. Investments and measures in stormwater management usually have relatively long life-times and are thereby sensitive to climate change and climate extremes. For proper and accurate decision making regarding these topics, planning is essential. However, the decision making process concerning the economic issues of stormwater management is often unclear. In this topic, an economic decision model, namely Cost-Benefit analysis (CBA), is used to evaluate and prioritize different sustainable urban drainage systems with the aim to aid the decision-making process regarding stormwater management.