The present study focuses on the application of spatial rainfall for the analysis of drainage systems. This is done based on a case area around Utterslev Mose in Copenhagen, including a hydraulic model of the area.

The study is divided into four parts, with the first three parts analyzing spatial rainfall. The first part solely deals with precipitation analysis, comparing the rainfall measured by the selected rain gauges and the C-band radar EKXS placed at Stevns. The second part of the report involves an analysis of model response using different spatial rainfall inputs and point rainfall. Initially, a complete rainfall series spanning around 15 years is examined, followed by an investigation of extreme events with a return period of 1 year or more. The third part of the report examines whether the use of an area reduction factor can describe the spatial distribution of rainfall and thus be used in the context of design.

Through the analyses in this study, it is evident that the application of spatial rainfall has a significant effect on the analysis of a hydraulic model. The analyses generally indicate that the use of point rainfall, which is the current design practice, is likely to result in an overestimation of drainage systems. This overestimation can be compensated for by using spatial rainfall.