How much water is in a river

Water cycle

Can a cycle get mixed up?

The water flows through its cycle, supplies animals and plants and constantly changes its shape: sometimes it flows in a wild river, sometimes it rushes in the sea, sometimes floats in the air, or lies as snow on the mountain peaks, sometimes it's sweet and sometimes salty. But how do you prevent a raindrop from tasting salty and the river water from making the sea water sweet? What happens if the water is suddenly missing at one point in the circuit or is of a different nature?

As long as the water cycle continues unhindered, nature regulates that the water retains the forms that we know and to which we have adapted. For example, evaporation on the surface of the sea causes water droplets to rise while the salt is left behind in the sea. This is how the vital rain forms, which replenishes our drinking water supplies and at the same time the salty habitat of the sea creatures is preserved. However, so that the salt content of the oceans does not increase increasingly, low-salt water must be replenished. This function is taken over by the rivers, without which the oceans would become arid salt reservoirs.

However, human interventions have contributed to the fact that the water cycle has already been unbalanced in some places: In Kazakhstan, for example, you can see the Aral Sea disappearing today: until 1960, it was considered the fourth largest inland lake in the world. Since then, the water from its tributaries has been taken to irrigate huge cotton plantations. Changes in water structures also disrupt the water balance of ecosystems. In order to make rivers navigable, side arms are often cut off. This leads to the loss of the water veins that supply the main stream of the river. These cut-off water sources usually dry up, causing many aquatic organisms to lose their habitat and the amount of water that the river brings to the sea decreases.