Seasonal water scarcity conditions for European river basin sub-units (sub-basins) for the four quarters of 2023, as measured by water exploitation index plus (WEI+)

The seasonal water exploitation index plus (WEI+) provides a measure of total water consumption as a percentage of the renewable freshwater resources available for the European river basins at subunit level. Each season is defined as a calendar quarter on the map: Q1 (January-March), Q2 (April-June), Q3 (July-September), and Q4 (October-December).

WEI+ results for EU Member States, Iceland, Norway, and Switzerland are presented at the subunit level, while for Italy, they are shown at the river basin level. For Türkiye and the Western Balkan cooperating countries, results are provided at the country level due to the lack of spatial data on river basins and subunits.

The EEA calculates the Water Exploitation Index plus (WEI+) for European river basins using a consistent approach for Renewable Water Resources (RWR). Due to limited data availability at the European level, the EEA applies significant gap filling, which may also result in differences from national estimates. In particular, Italy has noted that, due to the approach used by EEA for RWR, the pan-European index does not accurately reflect the detailed water stress conditions in its river basins.

The WEI+ for Switzerland and France may involve high uncertainties due to the use of modelled data as the baseline for the computation.

The WEI+ for Kosovo is highly uncertain because of missing information on reservoir changes and the complex hydrological relationships between inflows and outflows.

The WEI+ values for Bosnia and Herzegovina and for the river basins from Norway (i.e., NO1107, NO1108, NO1109, NO5107, and NO5109) represent the state of 2022 due to the lack of computed results for 2023.