World Scanning

WATER

Description

Although they hold less than half a percent of the earth's total freshwater, surface waters, including lakes, ponds, reservoirs, rivers, streams and wetlands represent 80% of the renewable surface water available in a given year. Loss and degradation of inland water habitats is widespread; it is estimated, for example, that by 1985 56-65% of suitable inland water systems had been drained for agriculture in Europe and North America. These water bodies provide a wide range of ecosystem services from drinking water, energy and recreation, to irrigation and transport, but the capacity of inland water systems to provide these services is in serious decline. Water eutrophication (a process where water bodies receive excess nutrients that stimulate excessive plant growth) and pollution are widespread in many countries reducing the capacity of inland waters to filter and assimilate waste, as well as having direct impacts on biodiversity.

The huge majority of the earth's unfrozen freshwater is found below the surface in aquifers as groundwater. Groundwater is theoretically renewable as long as it is not withdrawn faster than nature can replenish it, but in many dry regions it does not renew itself, or only very slowly, and intensive pumping is withdrawing it at unsustainable rates. Few countries measure the quality of groundwater or the rate at which it is being exploited which makes it difficult to manage.