Permanent gullies in the Nitra Hill Land, Slovakia : about the cause of gully formation

The paper deals with the spatial evolution of permanent gullies (under forest at present) in time in the northern part of the Nitra Hill Land (Slovakia) with the discussion on possible cause of their formation. For the purpose analyses of historical and current maps from the years 1783, 1838, 1882 and 2001 as well as aerial photographs from the second half of the 20th century and various historical written sources related to the years 1770, 1783, 1817, 1843 and 1956 were used. Based on the gained results an erosion activity of gullying can be found in the study area between the seventies of the 18th century to the sixties of the 20th century. Beyond the two main possible causes of the erosion activity as climatic change or (and) alteration in land use also conditions, such as agricultural system, different land use pattern, demographic characteristics or level of human society development may be considered.