Hydrology and drainage of peatland

Peat is an accumulation of partially decomposed plants, chiefly mosses, herbs, and trees, to form a deposit called bog. Complete decomposition is primarily inhibited by a deficiency of oxygen induced by waterlogging. In the upper layers of raised bogs and in the so-called blanket bogs, acidity and very low levels of phosphorus may also contribute to impairing decomposition. Peat types have been classified into blanket, raised, and fen peat. Further subdivisions have been made on the basis of the plant composition and degree of decomposition. Blanket peat is so called because it covers the landscape, hill and valley. On the other hand, raised peats are confined to low-lying ground and valleys, and higher ground often protrudes through as islands of mineral soil ground. The blanket/raised/fen classification has relevance to hydrology and drainage, in particular to the mode of formation and to the type of drainage solution including outfalls. The nature of the plant composition and degree of humification have relevance chiefly to physical properties but especially permeability, bulk density, and moisture content, which also relate to hydrology and drainage. This article examines the formation of peat in a hydrological context and the drainage of peat deposits through the application of drainage theory to the peat and subpeat deposits, including glacial drift and bedrocks.