Urban Flooding in Gothenburg – A MIKE21 Study / Urban översvämning i Göteborg – En studie med MIKE21
Climate change has affected the extreme weather throughout the world. Studies have shown an increase of extreme precipitation in Gothenburg, Sweden. A two dimensional (2-D) hydrodynamic simulation model using MIKE 21 was developed as a tool to simulate stormwater related flooding in the central part of Gothenburg. The model was developed using topographical data and high temporal resolution precipitation data. The topography data is first processed in ArcGIS so that it can be further used in MIKE 21. A bathymetry for the area is created in MIKE 21 considering boundary layers and other parameters including land value. For the Manning number, two cases were considered: in the first case, a constant value of 14 for Manning number was assumed over the entire computational grid and in the second case, a land use map was used with different Manning numbers for buildings, roads, parks and water. The model simulates unsteady flooding and drying processes over the urban areas. The developed two-dimensional model shows that the parts of the study area including the canals, the streets and the space in between the residential buildings would be flooded if the drainage system is blocked due to extreme precipitation. Flood maps with maximum water level have been generated and presented in the study. The findings from this model can be used for development of comprehensive urban flood management plan of Gothenburg.