Box 5A Definitions and sources

The renewable freshwater resource available for use in a country is the amount moving in rivers and aquifers, originating either from local precipitation over the country itself, or by water received from neighbouring countries in transboundary rivers and aquifers (Brouwer and Falkenmark, 1989). River runoff represents the dynamic component of the total water resource, as compared with the considerably less mobile water volumes in aquifers, lakes and glaciers. The groundwater contribution to river runoff is, according to Shiklomanov (1991), about 25 per cent of total runoff. Water abstraction (or water withdrawal) means water physically moved from its natural site of occurrence. The amount of abstracted water which is not returned to the site of abstraction after use is referred to as water consumption. Water use means all use of water, both in and outside the river, lake or aquifer.

National estimates of renewable water resources, including internal and external contributions, and water abstractions per capita are available for most European countries. Very often, however, the estimates vary between different information sources. For the purpose of this report, estimates of renewable water resources and water abstractions have been obtained for each country by updating the water resource database at Eurostat, with recent water resource statistics taken primarily from national reports prepared by many countries for presentation at the 1992 UNCED conference in Rio de Janeiro.