Aquatic organisms (fishes, invertebrates, plants) need for their life and development certain water
flow (ecological flow), which, throughout the year, should change according to the natural patterns
of variations (ecological regime).

The calculation of the ecological flow and regime for a particular water body requires the following
steps:

• Evaluation of ecological requirements of target species.
• Quantification of suitable habitat for these species under different flows.
• Mathematical modelling of suitable habitat area for each flow.
• Selection of a ecological flow and regime.