Aquifers
- Slovak term: Slovenský termín
- Layers of rock or sediments which are sufficiently porous to store water and permeable enough to allow water to flow through them (WHO/IWA, 2006)
Explanation
Materials which permit water to pass through them easily are said to be permeable and those which permit water to pass only with difficulty, or not at all, are described as impermeable. A layer of rock that is sufficiently porous to store water and permeable enough to transmit water in quantities that can be economically exploited is called an aquifer. Groundwater flow may take place through the spaces between the grains or through fissures, or by a combination of the two in, for example, a jointed sandstone or limestone. For any aquifer, distinguishing whether inter-granular or fissure flow predominates is fundamental to understanding the hydrogeology and to designing monitoring systems, particularly for point source pollution incidents (WHO et al. 1996).
Example
The introduction of drilled boreholes in the 1970s, and the identification of the Tawilah as a highly productive aquifer, encouraged farmers to use groundwater for irrigation. Having realised the importance of the Tawilah, the government tried to regulate agricultural water use in the area by passing a law in 1973 which identified a local protection zone around the NWSA wellfields and prohibited further drilling of new wells or cesspits unless permitted (WHO et al. 1997).
References
- WHO / IWA (2006) Protecting Groundwater for Health, Ed by Schmoll, Howard, Chilton
- and Chorus
- WHO/UNESCO/UNEP (1996) Water quality assessments: A guide to the use of biota, sediments and water in environmental monitoring, London, E&F Spon.
- WHO/UNEP (1997) Water pollution control: A guide to the use of water quality management principles, London,E&F Spon.
