Layer showing the major rivers.

Country Boundaries is a static map showing the country borders taken from the Geographic Information System of the European Commission (GISCO).

Important note: the GISCO dataset can be considered authoritative only for the EU28 and EFTA countries. The dataset outside Europe is based on UN GAUL (Global Administrative Unit Layers). The boundaries depicted therein normally (but not always) reflect the UN position. However, GAUL does not have an official authoritative status either, e.g. it is not endorsed by the UN Security Council. There are numerous disputed territories around the world and GISCO does not engage in providing an official position on most of them.

Disclaimer: The designations employed and the presentation of material on the map do not imply the expression of any opinion whatsoever on the part of the European Union concerning the legal status of any country, territory or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Layer showing major river basins of the world.

Layer combining the location of reservoirs and lakes included in the LISFLOOD hydrological model and the related estimate of the reservoir impact on the average flow.

GloFAS v5 reservoir dataset includes reservoirs with storage capacity ≥100 hm3, catchment area ≥500 km2, and degree of regulation ≥0.8. The total number is 1486 (an increase of +799 compared to GloFAS v4). 220 reservoirs included in global datasets had degree of regulation <0.8 and were modelled as lakes. The total of 1486 (+ 220 modelled as lakes) represents over 80% of the global total storage (an increase of over 20% compared to GloFASv4).

The GloFAS v5 lake dataset includes lakes with volume ≥100 hm3, catchment area ≥500 km2, surface area ≥50 km2. The total number is 1230 (1010 lakes plus 220 reservoirs modeled as lakes; an increase of +767 compared to GloFASv4).

The reservoir impact shows, along the GloFAS river network, how strongly river flow can be regulated by upstream reservoirs. It helps users judge where forecast discharge is likely to be affected by reservoir operations, and so where forecasts should be interpreted with extra care. For every river pixel, the impact is the total storage capacity of all reservoirs upstream divided by the mean annual discharge volume (based on the period of 1979-2025) at that pixel. Values are given only for rivers with upstream area above 250 km², mean discharge above 0.01 m³/s and at least one reservoir upstream. The ratio is the number of years of mean flow that the upstream reservoirs could store. A value of 0.1 means storage equal to about five weeks of mean flow; values close to or above 1 mean the reservoirs can hold a full year of flow and may dominate the flow regime. The index is static: it does not account for actual operating rules, reservoir filling levels, water abstractions or reservoirs not represented in GloFAS.

Inundated areas for flood events with a return period of 100 years, based on GloFAS climatology. Permanent water bodies derived from the Global Lakes and Wetlands Database and from the Natural Earth lakes map.

Drainage network of the LISFLOOD model. Rivers are shown as they are represented in the model. Lines show connections between the model pixels above 250 km² drainage area. The larger drainage area is represented by both darkening colours and increasing line widths.

Administrative regions merged using NUTS-2 or NUTS-3 classification from EUROSTAT and the region classification from GADM.

Lakes (the largest 463) and reservoirs (the largest 667) as included in the GloFAS model set up. Selection criteria are:
(1) lake surface area > 100km²;
(2) significant impact on river discharge;
(3) reservoir capacity > 0.5 km³.

The map illustrates the potential impact of reservoirs included in GloFAS on river discharge at global scale. To provide a continuous estimate of the potential reservoir effect along river reaches, the ratio of reservoir volume to mean annual discharge was calculated for each grid cell. This ratio makes use of the upstream cumulative reservoir capacity [m3] and the cell-specific total volume of annual natural river discharge [m³].