In the field of flood risk management the analysis and the prediction of flood damage is one of the key questions. In the past, a lot of attention has been paid to the analysis of riverine flood damages in large catchments and to the development of damage functions with the inundation depth as the most imported causal factor for flood damage. Local floods in urban area as a result of intense rainfall events, however, are not well understood.
Intense rainfall events cause local damage and are a common phenomenon during the summer months in Sweden. In this study, the role of rainfall intensity on local flood events was examined in the cities of Malmö and Gothenburg. Fifteen years of flood damage data, collected by a large Swedish insurance company, were analysed and a high correlation to rainfall intensities was found. Different rainfall intensities were examined and it seems to be considerable amounts of rainfall under a 60 minutes interval in combination with even shorter periods of high intense precipitation that generate flood damages. Another aim of the study was to find an approach for a damage function that describes the relationship between rainfall intensity and flood damage. Using regression methods, two non–linear approaches were estimated; the models reached degrees of explanation between 30 and 78 %.
The study has shown that rainfall intensity in a short time-scale is an important reason for flood related insurance damage during summer months, but it cannot be the only affecting factor. It is an issue for future research to make the damage function more complete. Further research will be undertaken to investigate the influence of other possible affecting factors, like the topography, the types of affected buildings, the local runoff pattern and socio-economic aspects.