A stormwater quality analysis of future conditions in urban areas - Case study of Kvillebäcken, Gothenburg
Examensarbete för masterexamen
Infrastructure and environmental engineering (MPIEE), MSc
Cities around the world are growing at a steady rate, which means they become denser with increased impervious surfaces. The imperviousness hinders the precipitation from infiltrate into the ground. The water flows as urban surface runoff, and transports pollutants trapped on the surfaces. These pollutants end up in a nearby waterbody and could potentially affect the aquatic environment and harm the organisms living there. The aim of the project was to assess how changes in land use, traffic and climate affect the stormwater quality in an urban area. The effects of exploitation and reconstruction was studied with the catchment area of the stream Kvillebäcken in Gothenburg as a case-study area. The planned constructions in the catchment area until year 2035 were mapped and simulations with six different scenarios were performed to investigate the result of densification of the area, with regards to four stormwater pollutants: copper, zinc, phosphorus and benzo(a)pyrene. The different scenarios consider the change in land use, climate, traffic and stormwater treatment measures. The result shows that the impervious area increases in the future, compared to current situation. However, with the planned stormwater treatment measures, the concentrations of the investigated pollutants in the stream Kvillebäcken decrease. Benzo(a)pyrene poses the largest problem in the future, as target concentrations are not met in the stream Kvillebäcken. Phosphorus might be a problem depending on if the proposed ponds by Sustainable Waste and Water get implemented or not, while copper and zinc do not seem to be a problem in terms of target concentrations. The conclusion is that all planned stormwater treatment measures from the zoning plans, and 50 % of the proposed ponds by Sustainable Waste and Water should be implemented to reach the targets for copper, zinc and phosphorus. Having more treatment would still not be enough to reach the target concentration for benzo(a)pyrene in the stream of Kvillebäcken due to other sources, due to benzo(a)pyrene origin from other sources than stormwater.