Practitioner Points
- Natural flow regimes of non-perennial Mediterranean rivers and streams
(NPRS) are classified using hydrological indices related to their
frequency, duration, timing, and rate of change in periods of flow
cessation
- Five indices describe the patterns of hydrological variability in
Mediterranean NPRS: number of days per year without flow, annual
percentage of months without flow, mean daily of annual flows,
coefficient of variation of Julian date of the annual start of zero
flow and annual rise rate
- Self-organizing map (SOM) categorize the NPRS into three groups with
similar hydrological features. This classification is compared with
others existing within the European Union. The similarities and
differences are discussed to provide useful information for the
development of specific assessment and management tools within the
scope of the WFD