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The plot below demonstrate the process for an example station on the Ganges river (Harding Bridge). It displays the empirical distribution of the extracted annual maxima and the flood threshold curve (out to return period 100 years) based on the Gumbel distribution. In this example for GloFAS v4, the considered reanalysis period was 1979-2022.
Adjusting for non-stationarity
The flood thresholds are generated from the unaltered annual maxima until GloFAS v4version 4, including the v1, v2 and v3 families. From the introduction of v5 in 2026, an annual maxima adjustment methodology was introduced that addressed the negative impact of the non-stationarity, i.e. large river discharge trend trends, in the GLoFAS GloFAS reanalysis that is present is some areas in the world, like the Congo basin or Southwestern US.
The adjustment methodology, used form GloFAS version 5, is described in more detail on this subpagepage: .