Sustainable Drainage Systems Assessment and Optimisation-A case study for Lussebäcken Catchment, Helsingborg

Abstract: Increase of urbanization and climate change are one of the factors that have been highlighted to influence hydrography. This is resulting in an increase in peak flow within an urban watershed. Downstream flooding and increased pollution are the problems that arises. To solve this, the sustainable urban drainage system techniques are adopted for reducing peak flow and increase baseflow. This thesis studies the assessment and optimisation of multipurpose constructed structures used in drainage systems in the Lussebäcken catchment in Helsingborg to reduce the possibilities of flooding while serving an environmental task. The water is transported from an upstream high plain catchment with a good fall height through Ramlösa ravine and discharges in the Råå Brook near the sea. Downstream within the low-lying area are residential buildings, industries and roads that are sensitive to flooding. Using the computer software MIKE URBAN with MOUSE engine, rainfall runoff was simulated and flow in the network system was computed. Three scenarios have been simulated; before 2008, when no additional ponds were added, the current situation with new constructed ponds and wetlands added to the model and a proposed modification to improve the regulation of the already existing infrastructures. The results show an improvement of over 20% of reduction of the peak flow in the main stream around the most critical area for the current situation over the 2008 situation and 8% more of improvement is obtained by regulating the output of one of the ponds. From the obtained results the main improvement could be made when storing capacity to the network rather than regulating the existing ponds.