by Lisa Pearce

Created on: February 04, 2009

Deep below the earths' surface the waters flow in the dark. No one ever witnesses the mysterious swirling, nor does anyone ever hear the mighty waters as it flows silently by. The underground water surges with energy and its own life-giving force, yet no living thing exists there. Sometimes the water is a mighty river, sometimes it is trapped in cracks and fissures in the rock. At times it lies still in secret underground caves, water dripping from above when it rains. It lurks there in the depths like a prowling predator, quietly, only to erupt in a white plume when its hiding place is discovered.

Groundwater is the inspiration for mystery and mysticism for some; it is in fact a crucial component of fresh water that sustains life on earth. In South Africa, groundwater accounts for only 13% - 15% of total water consumption. What makes this significant is the fact that around 65% of the population and 300 towns are completely dependent on groundwater for their existence (Colvin et al, 2008; WRC, 2005). In the US, almost half of the drinking water and 40% of irrigation water is pumped from aquifers, of which 30% is pumped solely from the world's largest known aquifer, the Ogallala Aquifer. Around 96% of rural areas and 20% urban areas in the US depend solely on groundwater for drinking water (Miller, 2000). Groundwater has the added benefit that it is usually filtered by rock through which it flows and delivers better-tasting drinking water WRC, 2005).

Underground water is contained in aquifers, that is, porous, water-drenched layers of sand, gravel or bedrock. Water movement in these aquifers is so slow that it usually travels only one meter in a year from a point of high elevation and high pressure to a point of low elevation and pressure. Aquifers are often found very deep underground and were formed in some instances as much as tens of thousands of years ago. These aquifers are in fact non-renewable resources and abstraction from them can be considered water mining (Miller, 2000).

Aside from drinking water and irrigation, groundwater serves many other purposes in the hydrological cycle and greater earth system: water trapped inside limestone caves maintain cavity pressure and prevent subsidence of the surface (sink holes); underground water replenishes above-ground rivers and streams in times of water stress; it prevents intrusion of salt water into fresh water in coastal areas (Miller, 2000) and it maintains biomes, such as the fynbos biome in the southern

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