ABSTRACT
In a generic sense, groundwater is a natural resource. This does not mean, however, that all groundwater on Earth has the real potential to satisfy human needs or desires. In the first place, some of it has to be discarded because its quality does not meet the water quality standards for its proposed uses, even after conventional treatment. Secondly, the exploitation of some groundwater bodies may be technically or economically unfeasible. Thirdly, the exploitation of groundwater may be subject to significant environmental constraints resulting from aspirations to conserve surface water, protect ecosystems or maintain the stability of the land surface. Therefore, only part of the ‘theoretical’ groundwater resources, represented by total flows and stocks, can be considered as
Running or stagnant surface water in rivers, streams and lakes is very different from groundwater in aquifers, in terms of where and how it moves at a given moment. In addition, unlike surface water, groundwater is invisible. The knowledge we have about each of the two is under the competence of different specialists: hydrologists versus hydrogeologists. The techniques to exploit them are also quite different: diversions and dams versus wells and boreholes. The differentiation according to exploitation technique is helpful for keeping separate records of their abstraction. However, it is important not to confuse source of supply with resource.
