Thank you very much for the draft report, which is indeed very interesting.
A couple of ideas for potential additional analysis:
1) Regarding the inclusion of climatic indices, a first easy step could be the use of a climate classification map, as it doesn’t require gathering any rainfall or temperature data. For instance, the updated map of the Köppen-Geiger climate classification of Peel et al. (2007). The map in raster format can be downloaded from the supplementary materials: Peel, M.C., Finlayson, B.L., McMahon, T.A. Updated world map of the Köppen-Geiger climate classification (2007). Hydrology and Earth System Sciences, 11 (5), pp. 1633-1644.
2) We could explore the topography differences between all catchments, and beyond elevation. An open source Digital Elevation Model with global coverage such as SRTM could be used to delineate the catchment boundaries and calculate topographic indices. This would involve some extra work and time, so maybe it could be considered in the future. Alternatively, we could calculate topographic indices only in the Austrian catchments with the DEM that has already been used.
3) Regarding future work, it could also be interesting to have a look at the paper of Serinaldi and Kilsby (2016). They analyze daily stream flow fluctuations exceeding high thresholds, and explore the relationship between the occurrence and magnitude of extreme flow values and the properties of the complete time series. Serinaldi, F., Kilsby, C.G. Understanding persistence to avoid underestimation of collective flood risk (2016) Water (Switzerland), 8 (4), art. no. 152.
Looking forward to seeing how the work develops!