Before the rapid development of science and technology in the 20th century, there was a certain equilibrium in the water cycle on the planet, that is, the amount of precipitation and the amount of moisture evaporated were approximately the same. Rivers calmly carried their waters in their channels. There have not been so many floods causing great damage to people, animals, buildings, plantings.
It is known from historical documents that the invention of the steamship had a negative impact on this balance. Man began to interfere with the calm flow of the rivers. Transportation of passengers and freight required deepening of shipping lanes on rivers, construction of ports and jetties, changes in channels. Multiple dredging of rivers led to the creation of a network of canals between major rivers and seas on the continents: the Baltic connected with the Black through the Volga and Don, the Black connected with the North through the Danube and Rhine. Obtaining electric power from hydroelectric turbines required the construction of many dams and the flooding of much land. Consequently, these actions also lead to disruption of the natural balance in nature. The development of agriculture in arid areas required the construction of irrigation canals, which in turn led to the disappearance of many rivers, lakes and even small seas in the late 20th century.
The industrialization of society has led to the formation of large sewage and wastewater settling tanks near cities. Fresh water use on the planet has increased dramatically in recent years.
The destructive activity of man continues. New engines, cars, and ships are being invented. River shipping is slowly dying out. Dredging of rivers stops. Consequently, rivers are becoming shallower, flowing out of their channels and flooding more and more land.