When low lying areas of land are drained, the general method is to dig drainage ditches. However, if the area is below sea level then it is necessary to pump the water upwards into water channels that finally drain into the sea.
The Victorians understood this concept, and in the United Kingdom they built pumping stations with water pumps, powered by steam engines to accomplish this task. In Lincolnshire, large areas of wetland at sea level, called The Fens, were turned into rich arable farmlandby this method. The land is full of nutrients because of the accumulation of sedimentary mud that created the land initially.
Elsewhere, pumping stations are used to remove water that has found its way into low-lying areas as a result of leakage or flooding (in New Orleans, for example).