Figure 4. Box-plots illustrate cluster groups obtained by training a self-organized map (SOM) with the selected indices; number of days per year without flow (DU035, in days/year), annual percentage of months without flow (FE052, in %), mean daily annual flows (MA001, in l/day), CV of Julian date of the annual start of zero flow (TI002) and annual rise rate (RC001, in l/day).