Specific location: town of Gardabaer
Ecosystem type(s): Urban ecosystem
Title/name of the NbS: Swales and rain gardens / Re-establishment of shallow lakes and ponds
Summary: Raingardens, swales and other blue-green structures implementation through urban planning of a new neighborhood Urriðaholt Garðabær in Island. Urridaholt is a hillside community in the town of Gardabaer, Iceland, developed and constructed mostly between 2003 and 2025. It is pioneering as a sustainable urban development and the first to be certified by the BREEAM Communities assessment standard in Iceland. It has received several international awards and recognitions for its approaches.
Contacts: Halldóra Hreggviðsdóttir, Alta consulting, www.alta.is. Chief planner of Urridaholt. halldora@alta.is
Relevant links to documentation:
Zaqout, T., Andradóttir, H.Ó. , and Sörensen, J. (2023). Trends in soil frost formation in a warming maritime climate and the impacts on urban flood risk, J. of Hydrology, 617, 128978
Zaqout, T., Andradóttir, H.Ó., and Arnalds, Ó. (2022). Infiltration capacity in urban areas undergoing frequent snow and freeze-thaw cycles: Implications on Sustainable Urban Drainage Systems, J. of Hydrology, 607, 127495
Zaqout, T. and Andradóttir, H.Ó. (2021). Hydrologic performance of grass swales in cold maritime climates: Impacts of frost, rain-on-snow and snow cover on flow and volume reduction, J. of Hydrology, 126159
Andradóttir, H.Ó., Arnardóttir, A.R. and Zaqout, T. (2021). Rain on snow induced urban floods in cold maritime climate: Risk, indicators and trends, Hydrol. Proc., 14298
Extended case description: Raingardens and swales can be established to protect the water level and environmental quality lakes or wetland close to urban areas. The structures also helps the towns and villages adapt to climate change. Traditional methods of dealing with stormwater used during planning and construction, would frequently extinguish lakes and wetlands close to urban settlments and their environment.
Instead, in Urriðaholt Garðabær a new neighborhood of around 5000 inhabitants, swales and raingardens are interwoven into the urban infrastructure to retain, treat and carry the stormwater within the watershed of the surrounding wetland. As an example, a trapezoidal-section swale in Urriðaholt, Gardabaer, Iceland, reduced peak flow by 20–40 % and infiltrated 30–60 % of runoff during the spring-summer seasons (Zaqout and Andradóttir 2021). The aim in Urridaholt was to create a quality sustainable environment for people and the ecosystem of the Urridavatn lake and surrounding wetland.
The Urridaholt master plan was developed in close cooperation between political leaders and professionals from many fields with community participation, emphasizing quality of life and sustainability. It sets an example for interdisciplinary cooperation and serves as an international laboratory for scholars and leaders.