Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-504 Manuscript under review for journal Hydrol. Earth Syst. Sci. Discussion started: 19 October 2018 c Author(s) 2018. CC BY 4.0 License. Rain erosivity map for Germany derived from contiguous radar rain data Franziska K. Fischer1,2,3, Tanja Winterrath4, Karl Auerswald1 1Lehrstuhl für Grünlandlehre, Technische Universität München, Freising, 85354, Germany 5 2Bayerische Landesanstalt für Landwirtschaft, Freising, 85354, Germany 3Außenstelle Weihenstephan, Deutscher Wetterdienst, Freising, 85354, Germany 4Deutscher Wetterdienst, Department of Hydrometeorology, Offenbach/ Main, 63067, Germany 10 Correspondence to: Karl Auerswald (
[email protected]) Abstract. Erosive rainfall varies pronouncedly in time and space. Severe events are often restricted to a few square kilometers. Rain radar data with high spatio-temporal resolution enable this pattern of erosivity to be portrayed for the first time. We used radar data collected with a spatial resolution of 1 km² for 452 503 km² to derive a new erosivity map for Germany and to analyze the seasonal distribution of erosivity. Extraordinarily large filtering was necessary to extract the 15 expected long-term regional pattern from the scattered pattern of events. Filtering included averaging 2001 to 2017 and smoothing in time and space. The pattern of the resulting map generally agreed well with the previous map based on regressions of rain gauge data (mainly from the 1960s to 1980s). The pattern was predominantly shaped by orography. However, the new map has more detail; it deviates in some regions where the regressions previously used were weak; most importantly, it shows that erosivity is about 66% higher than in the map previously used.