The statistical analysis used (Principal Component Analysis followed by a classification method) to identify groups common to all months and describe the evolution of these groups during the year. The data used allows for monthly tables showing the selected parameters, calculated over the entire geographic area with a resolution of 0.1 °. This method identifies 10 hydrological landscapes present at various times of the year, and characterized by homogeneous hydrological conditions.

The distribution of hydrological landscapes is determined by a method of comparing multi-tables, to identify groups of individuals with similar variability of hydrological conditions during the year. The data used provides monthly tables showing the selected parameters, calculated over the entire geographic area with a resolution of 0.1 °. The variable chlorophyll-a is extra: it does not contribute to the discrimination of groups. This method identifies 10 hydrological landscapes with a similar annual variability of hydrological conditions.