City dwellers are willing to pay for sustainable drainage systems

Overview

In Valuing ecosystem services of sustainable urban drainage systems: A discrete choice experiment to elicit preferences and willingness to pay, published in the Journal of Environmental Management, Daniel Johnson and Sylvie Geisendorf examine the preferences of urban residents and their willingness to pay for sustainable urban drainage systems (SUDS) in the context of Berlin (Germany).

Why study this

Sustainable urban drainage systems, which include ponds, swales, green roofs, permeable pavements, etc., allow for a more natural water cycle in urbanized areas through increased infiltration, evaporation and retention of stormwater at source. These stormwater management solutions also provide ‘ecosystem services’: they reduce urban heat islands, enhance biodiversity, improve the quality of groundwater and increase the aesthetic quality of the environment. Yet these are non-marketable benefits. By quantifying the value attributed by residents to these services, this experiment facilitates their inclusion in cost-benefit analyses for more efficient urban planning.

Findings

• Overall, respondents value improvements of ecosystem services provided by SUDS, i.e. fewer hot days per year, improved water quality, richer biodiversity, urban attractiveness.
• Respondents express a willingness to pay a significant additional monthly stormwater charge for the provision of ecosystem services by SUDS.
• The most important attribute is the alleviating of fish die-offs, as indicated by a willingness to pay a 19 € monthly surcharge to eliminate them completely and a 12 € surcharge to reduce fish die-offs by half.
• Residents expressed a willingness to pay an extra 10 € and 13 € per month to improve the aesthetics of the city, with respectively a few new green interventions and many new green interventions.
• Improvements to biodiversity were valued with willingness to pay responses of 11 € and 8 € depending on the level of improvement.
• While reducing urban heat seemed to provide the least value to respondents, they nonetheless estimate that they are ready to pay an extra 6 € a month for twelve less hot days per year and 2 € per month for two less hot days per year.

Key insight

Urban residents value the ecosystem services provided by sustainable urban drainage systems and are willing to pay above the current stormwater charge for their implementation.

Impact

By demonstrating that residents value the ecosystem services provided by SUDs, this study provides grounds for policies and urban planning concepts to improve the uptake of such systems in urban areas such as Berlin. In addition, by weighing the importance urban residents attribute to each aspect, policy-makers can better prioritize measures and make strong economic arguments for implementing different SUDS.

Final takeaways

“Through urbanization and climate change, urban areas face a multitude of issues from urban heat to stormwater management problems. Given these issues, SUDS are posed as one solution directly aimed to improve the handling and treatment of stormwater. SUDS measures, such as green roofs, façade greening, tree drains, swales and ponds, (...) offer urban residents the increased provision of several ecosystem services including reduced extreme heat, improved water quality, more urban habitats and higher aesthetic quality of surroundings.”