Drainage systems

The excessively wet climate in Estonia causes swamp formation, as the annual precipitation exceeds the annual evaporation approximately two times. In the long term, ongoing swamp formation has caused a consistent decline in soil fertility and in the growth of forest stands and a partial displacement of forests by swamps. Long-term swamp formation finally resulted in the displacement of one-time excessively wet forests by forest and shrub swamps, and sedge fens by bogs.

First drainage ditches are known to have been dug in Estonia in the 1920s, intentional drainage was done from the 1940s. The volume drainage operations peaked 1969-1975; when about 150 000 ha of forest lands was drained. According to various data, a total of 700 000 ha of forest lands have been drained in Estonia, 450 000 ha is in state forest.