The degree of peatland subsidence resulting from drainage of land

The paper presents the degree of subsidence in stratigraphic transects and a change in soil morphology. The degree of subsidence was determined based on direct geodetic measurements taken in 1974 and 2012 and additionally with the use of empirical relationships of subsidence with the depth of drainage and peat properties. The histic horizon is built of peat thickness of 3 m on the Sosnowica and 0.64 m on the Uhnin. The value of subsidence of Histosol, measured by geodetic means, ranged from 9 to 33 cm, while that of Gleysol from 0 to 4 cm. The mean value of subsidence of the peatland in Sosnowica amounted to 24 cm over 38 years, which gives a degree of subsidence of 0.6 cm year(-1), i.e. a loss of peat mass amounting to 11.5% of the total resources. The situation is still worse in the case of the peatland in Uhnin, where mineralization and a fire of the peatland caused the peatland area to shrink by 36%. The loss of peat mass, including loss due to fire, accounted for 53% of the total resources, which corresponds to a degree of subsidence of 0.35 cm year(-1). In engineering practice, the degree of subsidence can only be determined according to Jurczuk's formula taking into account environmental factors and the passage of time.