Last updated: March 2025
The Gårda pilot rain garden has been constructed as part of the research project Innovative Rain Gardens at Chalmers University of Technology in Gothenburg. In addition to causing flooding, runoff rain water in urban environments can be contaminated with microplastics, organic pollutants and metals which can spread into the natural environment. Yet, most of the storm water in urban environments is not treated. The purpose of the Innovative Rain Gardens project is to research the ability of a pilot rain garden to treat such pollution. The project acknowledges the function of a rain garden to prevent flooding, but in this study only the pollution treatment potential is investigated. The pilot rain garden was constructed next to the E6 highway in central Gothenburg [Ref. 1-4]. It includes several different bioretention filters where selected plants are grown in filters containing different materials such as biochar, ash and soil [Ref. 2, 3]. Results so far show that the use of rain gardens can significantly reduce pollution. However, further research is needed to determine the long term function of the bioretention filters and the potential of scaling up the NBS. The project is funded by the Swedish Research Council for Sustainable Development (Formas), IMMERSE - Implementing Measures for Sustainable Estuaries, an Interreg project supported by the North Sea Programme of the European Regional Development Fund of the European Union, and COWIfonden (private foundation) [Ref. 1-3].
Location of the Gårda rain garden shown at different scales.
https://www.sciencedirect.com/science/article/pii/S0304389424001110?via%3Dihub#sec0095
Overview
Nature-based solution
- Green areas for water management
- Rain gardens
Key challenges
- Climate action for adaptation, resilience and mitigation (SDG 13)
- Climate change adaptation
- Water management (SDG 6)
- Flood protection
- Stormwater and rainfall management and storage
- Improvements to water quality
Principal problems in Functional Urban Area (FUA)
- Climate-Related Hazards
- Urban flooding (stormwater)
- Environmental Degradation
- Poor water quality
Key priorities
Climate action (adaptation and/or mitigation)
Focus
Creation of semi-natural blue areas, Implementation of green areas for water management (e.g. rain gardens), Knowledge creation and awareness raising, Scientific research of biodiversity or ecosystems
Project objectives
The project aims to improve the multi-functionality of rain gardens by, in addition to preventing floods, promote the treatment of pollutants [Ref. 1-3]. The stated objective of the scientific study are to:
- "Design and construct an innovative and sustainable pilot-scale rain garden to effectively remove microplastics and other pollutants.
- Evaluate absorption materials such as peat, biochar, and ash as bed material, with and without plants.
- In the pilot, an in-depth study of the processes in the rain beds for removal, distribution, degradation, potential uptake in plants, and possible leaching of microplastics and other pollutants." [Ref. 2]
Implementation activities
1. The project was created as a Cross-Border-Collaboration between COWI AB (Sweden), Chalmers University of Technology (Sweden), and Aquateam COWI (Norway) [Ref. 1].
2. The project applied for and recieved funding from COWIfonden (a private fund), FORMAS (a Swedish government research council), and the EU Interreg program [Ref. 1, 2].
3. The experimental rain garden was set up next to a highway, and included bioretention filters with different soil or substrates and different plant species. The pollution contents of stormwater coming into and out of the filters was tested [Ref. 2, 3].
4. In 2023, a report was published on the project website with the initial results of the study [Ref. 2].
5. Additional results were published in a scientific journal in 2024 [Ref. 3].
6. The study will continue for a few years as part of a PhD and be published in the future thesis [Ref. 2].
Climate-focused activities
Climate change adaptation:
- Implement sustainable urban drainage schemes to manage stormwater
Main beneficiaries
- Private sector/Corporate/Company
- Researchers/University
Governance
Management set-up
- Led by non-government actors
Type of initiating organisation
- Researchers/university
- Private sector/corporate actor/company
Participatory approaches/ community involvement
- Unknown
Details on the roles of the organisations involved in the project
"The project is facilitated by a Cross-Border-Collaboration between COWI AB (Sweden), Chalmers University of Technology (Sweden), and Aquateam COWI (Norway)." [Ref. 1]. The project is a research project, part of a PhD project, at Chalmers in collaboration with COWI, which is a private consulting firm, and Aquateam COWI, a research institute funded by COWI. All of the researchers listed as co-authors in the publications about the project are employed either at Chalmers or COWI/Aquateam COWI [Ref. 2-3]. Recycling and waste company Renova and the Swedish National Road and Transport Research Institute are also involved but the individuals from those organisations are also connected to Chalmers [Ref. 3-4]
Project implemented in response to ...
... an EU policy or strategy?
Unknown
... a national policy or strategy?
Unknown
... a local policy or strategy?
Unknown
Type of enablers
NBS research project (e.g., H2020, Urban Living Labs, national research projects)
Financing
Total cost
Unknown
Source(s) of funding
- Research organisation / University
- EU funds
- Private Foundation/Trust
Type of funding
- Direct funding (grants, subsidies, or self-financed projects by private entities)
Non-financial contribution
Unknown
Impacts and Monitoring
Environmental impacts
- Water management and blue areas
- Improved water quality
- Achieved improved water quality
- Increased protection against flooding
- Expected increased protection against flooding
- Improved stormwater management
- Expected improved stormwater management
- Enhanced protection and restoration of coastal and marine ecosystems
- Expected enhanced protection and restoration of coastal and marine ecosystems
- Enhanced protection and restoration of freshwater ecosystems
- Expected enhanced protection and restoration of freshwater ecosystems
Economic impacts
- Unknown
Socio-cultural impacts
- Education
- Increased support for education and scientific research
- Achieved increased support for education and scientific research
- Increased awareness of NBS and their benefits
- Achieved increased awareness of NBS and their benefits
Type of reported impacts
Presence of formal monitoring system
Yes
Presence of indicators used in reporting
Yes
Presence of monitoring/ evaluation reports
Yes
Availability of a web-based monitoring tool
No evidence in public records
Potential risks of implementation and trade-offs
Unknown
References
1.
Hvitt Strömvall, A.-M. (2023). About the project. Chalmers University of Technology, Accessed on August 16, 2024, [Source link];
2.
Johansson, G., Karlfeldt Fedje, K., Andersson-Sköld, Y., Modin, O., & Strömvall, A.-M. (2023). IMplementing MEasuRes for Sustainable Estuaries (IMMERSE): Report for WP 4.7 Innovative Rain Gardens for Sustainable and Effective Treatment of Urban Runoff Polluted with Microplastics and other Pollutants . Interreg North Sea Region, [Source link];
3.
Johansson, G., Karlfeldt Fedje, K., Modin, O., Haeger-Eugensson, M., Uhl, W., Andersson-Sköld, Y., & Strömvall, A.-M. (2023). Removal and release of microplastics and other environmental pollutants during the start-up of bioretention filters treating stormwater . Journal of Hazardous Materials, 468, Article 133532, [Source link];
4.
Karlfeldt Fedje, K. (n.d.). Innovative rain gardens to filter microplastics from stormwater . Renova AB, [Source link];
Bioretention filters, showing plant growth over time
https://doi.org/10.1016/j.jhazmat.2024.133532
Information about this nature-based solution was collected as part of the Naturescapes project funded by the European Union under Grant Agreement No 101084341.