STORMAN

Rainfall is projected to increase in Nordic countries, especially in the form of extreme events. Nordic cities are however not well prepared to manage a larger volume of stormwater. In Gothenburg the central part of the city uses a combined system which uses a single pipe network to transport both stormwater and sewage to the municipal wastewater treatment plant. Extreme rain events have resulted in the discharge of untreated sewage into receiving water, causing potential health risks and difficulties in meeting water quality regulations. In addition, approximately 200 ODO m3 of household sewage are released annually owing to lack of capacity . The municipality is currently reviewing the responsibility for stormwater management in the planning process. Planning and building regulations have been unclear up until now, leading to inadequate stormwater management in many new plans and buildings despite recommendations that stormwater should be handled locally.

Blue green solutions (including green roofs, reinforced grass and bioretention planters) have been used for climate mitigation through increased stormwater retention and local water treatment. Such solutions are already in use and their potential for stormwater management has been assessed in research projects such as the Climate-KIC funded Blue Green Dream. While blue green solutions have a technology readiness level (TRL) of 7-10, we will develop a toolbox for decision makers to better identify costs and benefits of the solutions, including climate mitigation and adaptation benefits.

This Pathfinder will assess the need for a comprehensive toolbox for decision­ making and technology selection in the implementation of blue green solutions in urban areas. The toolbox will support decision-making by providing a comprehensive assessment of costs and benefits of local solutions, including climate adaptation and mitigation. We will assess the market potential of the toolbox as well as specify stakeholder information needs for decision making.