CyberDodo and ground water tables (1-53)
As we saw in the case file on water, 70% of our planet is covered in water, which could lead us to believe that it is a renewable resource. Everything changes when you look at the situation from the point of view of a human being who needs fresh water to survive
Because the figures are no longer the same at all; out of 100 drops of water that fall on earth, 97 are salty, therefore they can not be consumed directly by humans - there are only 3 drops of fresh water, but 2 out of these 3 drops are in an iced state.
Human beings can therefore only rely on 1 drop of water out of 100, and this is without even subtracting anything, because 65 % of this meagre resource is taken up by irrigation of crops and another 20% by industry!
Do you understand our title better: Fresh water is very precious ? In this context where accessible fresh water is very rare, ground water tables become as precious as hidden treasure however, what is a ground water table?
It is a reservoir created by nature which holds water. This reservoir consists of a floor that has a waterproof bed which stops water from penetrating beneath it.
Why are ground water tables so important?
We have already seen that a little more than a tenth of a drop of fresh water (out of 100) is availabe for direct consumption by man, which is very little. Pay attention, because this phrase will explain the issues at stake in this case file: 95% of this rare resource is stored in ground water tables. In other words, the future of man depends on the water contained in these natural reservoirs because they provide a half to a quarter of our water for consumption, depending on the countries.
But the ever increasing encroachment of the human species, as well as pollution, are a serious threat to the environment.
To understand this, let's imagine that we are out in the wild, man has not yet ravaged the earth and it is raining. After being soaked up by the vegetation and drunk by the animals, the remaining water slowly inflitrates the soil, penetrating the mineral beds as it gradually flows through the different geological strata. In one phase, it encounters a waterproof bed, such as clay, and will accumulate in order to set up a ground water table.
When the surface soil is filled with water, it will flow until it joins rivulets, rivers, dams, etc which in turn flow into lakes and seas. Later, this water evaporates, forming clouds that will give rain, etc.
A perpetual cycle, in fact, until man became involved, and because of his obsession with turning everything into concrete, water from towns no longer directly infiltrates the earth, but is collected and then goes to water purification stations where it comes into contact with pollutants which shall be more or less properly processed before the water is rejected to nature.
At the worst, after having washed through the roads and drains that are filled up with all types of garbage, the water then reaches the ground water tables, which it will pollute.
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