The influence of infiltration and rain intensity on an urban pluvial flood model : A case study of a catchment in Malmö municipality

Abstract: Urban pluvial floods have become more and more common in Europe. These floods have resulted in high costs for society, increasing the interest in conducting hydraulic flood models. This in order to prepare and minimise the consequences of these flood events. The study looked at how changing the temporal distribution of the rain using six type events, and whether using the runoff coefficient method or infiltration method in such a model, would impact the flood extent and flood depth for a 100-year return period rain event. The model is made using MIKE+ for a catchment area in Malmö, Sweden.  The results showed that the runoff coefficient method generally overestimated both the flood extent and the maximum flood depth compared to the infiltration method. The differences were however very small between the methods, only between 6-7% over the catchment. For the six different temporal distributions for the rain event, the conclusion could be drawn that the flood extent follows a clear pattern from largest to smallest while no individual type event could be seen to give the deepest flood. Instead, this varied across the different evaluation points.