How to adapt the stormwater system in your city to the climate change - this question was an umbrella for the discussion at the last UBC TALKS: stormwater on 28 April.

However, some questions left unanswered: we share an interview with the experts from Copenhagen, Helsinki and Gdańsk on raising motivation for the change, effects of COVID and benefits of implementing green infrastructure in the cities.

— Is there motivation and political commitment to implement new stormwater solutions and what can be the obstacles to it in your cities?

Copenhagen: The political commitment is high, but there are more obstacles now compared to the first years after the flooding disaster in 2011, especially within discharge permits and arranging street drains. There is especially a need to develop solutions to treat separate rain run-off from the inner city because of little space available.

Helsinki: The city has a stormwater management program which is politically accepted by the city board and the city is committed to implement it. The awareness and motivation for implementing sustainable stormwater solutions is rising, but of course sometimes it can be challenging in practice.

As always, money is a question and, in some occasions, maybe also lack of knowledge of possibilities. However, I think that the biggest obstacle is not inventing new solutions, but having new solutions taken into normal procedures.

Gdańsk: The city authorities are aware of the importance of the problem and they link these phenomena with the issue of climate change. This is the result of intensive rainfall phenomena that have occurred in previous years. Municipal Adaptation Plan (MAP) for climate change for Gdańsk, which was developed few years ago, includes solutions for green infrastructure supporting urban retention. It is worth emphasizing that Gdańsk is the only Polish city with a dedicated company which operates and maintains stormwater and drainage infrastructure.

There are several types of obstacles we can identify. Legal: the law hindering the implementation of small retention solutions (f.ex. through lengthy procedures for small facilities). Organizational: complicated procedures for issuing legal water permits. Knowledge: lack of proper education of specialists at the universities, lack of understanding of water management processes and the need to implement green infrastructure among designers and officials.

— Are the green infrastructure solutions that are implemented in your city more expensive than conventional end of pipe solutions?

Helsinki: This is a tricky question, as it is hard to compare these two. In the CITYWATER project in Helsinki we made a cost-benefit analysis in which we compared all costs and benefits (direct and indirect) for the entire life cycle of a wetland system (situated in City of Lahti) to a pipe system and it showed that in the long run, the overall benefits (such as climate change adaptation, biodiversity, recreational possibilities) gained from the stormwater wetland seemed to exceed the overall costs. However, if you just compare the construction costs for the stormwater solution with the construction costs for the pipes, I guess the sustainable one is more expensive but then you would not take into account all the multiple benefits that the sustainable management brings.

Many of the sustainable solutions are quite new, and there is thus not that much long-term data for more comprehensive comparisons, which would of course be important to make in the future.

Gdańsk: According to our experience, green infrastructure solutions are cheaper and more effective. If they are introduced at the investment stage, they may not even cause an increase in investment costs. Changing the way of land developed by lowering lawns and designing space to retain water and slow down runoff is not expensive. It is more difficult to convince investors and designers to such approaches.

Copenhagen: The water company can finance green solutions if they are cheaper than conventional piped solutions. The more green they are, the smaller are the pipes and tunnels for transporting flood water.

— Does the COVID-19 outbreak influence stormwater management in your city?

Gdańsk: Both the city and the Gdańsk Water company have adapted their work organization so that safety is not compromised. Thus, continuity of processes related to drainage system management is maintained.

Helsinki: I would think, that the COVID-19 outbreak has not had a significant effect on stormwater management within the city. The water utility has of course been very busy, but this mainly concerns, to my knowledge, handling of wastewater management.

Copenhagen: At the moment there is no real influence.

We would like to sincerely thank the representatives of the cities for the provided insights: Jes Clauson-Kaas (Copenhagen), Kajsa Rosqvist (Helsinki), Magdalena Gajewska (Gdańsk).