The main function of a drainage system is to allow the withdrawal of water that accumulates in topographic depressions in the terrain, causing inconveniences either to agriculture or in urbanized areas or roads.

The origin of the waters can be:

Another extremely important function of the drainage system is to control, in the irrigation perimeters, the accumulation of salts in the soil, which can drastically reduce productivity.

Mainly, the drainage system is made up of a network of channels that collect and conduct water elsewhere, outside the area to be drained, at the same time preventing the entry of external waters. Typically these systems are necessary in the wide estuaries of large rivers and in valleys where natural drainage is poor.

The network of channels or channels must be periodically cleaned, eliminating the mud that is deposited in them and the weeds that grow at the bottom and on the slopes, otherwise the flow of water would very easily be modified and the efficiency of the system would be lost.

When the land that must be drained is all at a higher level than the work or container where the drained water is to be taken, the natural slope of the land can be taken advantage of and the system works perfectly with the force of gravity. Otherwise, a pumping station must be implemented.

When the area to be cleaned is at a lower level than the surrounding areas, and a river with considerable solid transport is available, the filling of low-lying land can be caused to allow sediment to be deposited and thus raise its level.

This operation has been done a lot in the past, thereby eliminating extensive areas of lowland. The current conception no longer considers this type of intervention convenient.

In some cases, meteoric water must be pumped, since there is no possibility of it coming out naturally. The first installations of this type occurred in the 19th century, in Europe, with steam-powered pumps.

The introduction of internal combustion engines and later electric motors substantially modified the capacity and characteristics of drainage systems, which became increasingly flexible and powerful. In the 20th century, the need to expand the agricultural frontier and the need to counteract the endemic diseases that plagued the population of low-lying coastal areas have given great impetus to the implementation of drainage systems, and generated the construction of important drainage systems that allowed the drainage of vast areas.

The components of a typical drainage system are:.