Water is the basis of all life on earth. Whether as drinking water, energy source, transport medium, raw material or as a habitat for a multitude of plants and animals in streams, rivers, lakes, wetlands or seas - water is an important, if not the most important resource on our planet.
Just like energy, water is not consumed or destroyed. It is subject to a continuous cycle of precipitation, runoff and evaporation - and its total quantity on earth is always the same.1)
But: Most of the approximately 1.4 billion cubic kilometres of the world's water reserves are salt water. Only around 2.5% of this is fresh water, of which more than two thirds is trapped as ice at the poles, glaciers or in permafrost soils and is therefore not directly available to us. Only around 0.3% of fresh water is relatively easily accessible to humans.2) 70% of this drinking water is obtained as a natural product from groundwater or spring water. 13% is used directly from lakes, reservoirs and river water, or it exists as a mixed form similar to groundwater, such as surface water, which is obtained through soil passage or bank filtration.3)
In addition to the sometimes costly extraction process, any contamination is problematic. If, for example, pathogens, foreign bodies or other inputs (such as pesticides or industrial toxins) contaminate the available fresh water, it is not suitable as drinking water for humans and animals without pre-treatment. The global distribution of usable freshwater also causes difficulties. If too little rain falls in a certain period of time in a region, the crop harvest is jeopardised by drought without further irrigation measures. If too much rain falls, layers of soil can be washed away so that plant growth is also impaired, e.g. due to a lack of root support, nutrient deficiency or (moisture) rot. Such regional differences in water availability are caused by an uneven distribution of precipitation, runoff and evaporation, but also by excessive water consumption or human pollution.
Let us therefore return to the highly simplified water balance equation mentioned above. For short-term considerations, this must be supplemented by the change in storage due to reserves (e.g. in lakes, dams, glaciers, etc.) and utilisation (e.g. water use by agriculture, industry, households, etc.):
Precipitation = runoff + evaporation + (reserve - utilisation) 4)
Agriculture is the largest "user", accounting for around 70% of the approximately 4,000 cubic kilometres of fresh water extracted worldwide each year. And rainwater (= a further approx. 6,400 cubic kilometres), which rains down directly over the fields, is not yet included in this figure. On average, 20% is consumed worldwide in industry and 10% at municipal level.2)
However, there are major regional differences in water withdrawal. In Western Europe, for example, the industrial sector already accounts for more than 70%, meaning that only a correspondingly smaller proportion is withdrawn for the agricultural sector.2) And as water is generally not consumed but only used, it is still available to the water cycle after use, but in altered (= usually deteriorated) quality.5) It can then no longer be used as drinking water or for the production of food - or only after complex and cost-intensive treatment measures.
In our search for traditional methods of food production, we will also take into account the regional characteristics in relation to the water that is potentially naturally available. We are curious to find out which original solutions are still used locally today for the production of fresh and drinking water, transport and storage for food production.
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Our next article will continue with a plant-based food:
References:
1) Wikipedia, 2024: Wasser, taken from the internet on 10.04.2024, https://de.wikipedia.org/wiki/Wasser
2) bpb Bundeszentrale für politische Bildung, 2017: Wasserverbrauch, taken from the internet on 11.04.2024, https://www.bpb.de/kurz-knapp/zahlen-und-fakten/globalisierung/52730/wasserverbrauch
3) Umwelt Bundesamt, 2019: Trinkwasser, taken from the internet on 10.04.2024, https://www.umweltbundesamt.de/themen/wasser/trinkwasser
4) Spektrum.de, 2024: Wasserhaushaltsgleichung, taken from the internet on 11.04.2024, https://www.spektrum.de/lexikon/geographie/wasserhaushaltsgleichung/8883
5) Wikipedia, 2024: Wasserverbrauch, taken from the internet on 11.04.2024, https://de.wikipedia.org/wiki/Wasserverbrauch