What is ground water?
When water falls as rain or snow, much of it either flows into rivers or is used to provide moisture to plants and crops. What is left over trickles down to the layers of rock that sit beneath the soil.
And just like a giant sponge, this ground water is held in the spaces between the rocks and in the tiny inter-connected spaces between individual grains in a rock like sandstone.
These bodies of wet rock are referred to as aquifers. Ground water does not sit still in the aquifer but is pushed and pulled by gravity and the weight of water above it.
The movement of the water through the aquifer removes many impurities and it is often cleaner than water on the surface.
Africa Has Vast Hidden Water Resources, But They Must Be Used Wisely
“There is enough water for human need, not human greed.” ~Mahatma Gandhi
Africa is a notoriously dry continent, but things may not be as bleak as one would suspect as climate change advances.
Currently, the situation appears bad. At present only about 5% of arable land is irrigated. Across Africa more than 300 million people are said not to have access to safe drinking water. Water for sanitation is in short supply. Demand for water is set to grow markedly in coming decades due to population growth and the need for irrigation to grow crops.
Yet, a BBC report says that Africa is sitting on a vast reservoir of groundwater–with pools suspected to contain 100 times the amount to be found on the surface.
Researchers have for the first time been able to carry out a continent-wide analysis of the water that is hidden under the surface in aquifers. Researchers from the British Geological Survey and University College London (UCL) have mapped in detail the amount and potential yield of this groundwater resource across the African continent.
The researchers say their new maps indicate that many countries currently designated as “water scarce” have substantial groundwater reserves.
The new mapping that shows formerly unsuspected ground water resources leads to cautious optimism. Caution is necessary because although there are vast groundwater reserves, experts believe that rapid extraction through large boreholes might not work in the region and that moderation in harvesting groundwater may be necessary. The lead author of the study told the BBC: “High-yielding boreholes should not be developed without a thorough understanding of the local groundwater conditions. Appropriately sited and developed boreholes for low yielding rural water supply and hand pumps are likely to be successful.”
Water was added to the aquifers over 5000 years ago. It must be harvested respectfully.