Figure 3. Self-organizing map (SOM) for the variables: number of days per year without flow (DU035), annual percentage of months without flow (FE052), mean daily annual flows (MA001), CV of Julian date of the annual start of zero flow (TI002) and annual rise rate (RC001). Warm colours (yellow) indicate high values while cool colours (blue) represent low values for each variable. The U-matrix (unified distance matrix) and cluster classification applied to the boundaries of the map is added.