European catchments and Rivers network system (Ecrins), natural sub basins of Europe - version 0, Dec. 2011
Description
The natural sub basins of Europe is a feature dataset which subdivides natural basins bigger than 40,000 square Kilometres into sub catchments of a surface between 10,000 square Kilometres and 40,000 square Kilometres. Sub basins are defined using the catchment area of big tributaries as much as possible, and subdividing the main course of the river into upper, medium, and lower parts of the basin. The target is having a spatially homogeneous, but still with hydrological meaning units. These subdivisions are nested when river basins are big and tributaries drain a surface bigger than 40,000 square Kilometres, which in the case of Danube and Volga makes up to 3 levels of sub basins.