Jakab G.,MTA Foldrajztudomanyi Kutatointezet Termeszetfoldrajzi Osztaly |
Jakab G.,Hungarian Academy of Sciences |
Kertesz A.,MTA Foldrajztudomanyi Kutatointezet Termeszetfoldrajzi Osztaly |
Madarasz B.,MTA Foldrajztudomanyi Kutatointezet Termeszetfoldrajzi Osztaly |
And 2 more authors.
Journal of Landscape Ecology | Year: 2010
Soil erosion is one of the most important processes in recent slope evolution. This process causes rapid and considerable changes in microtophography especially on tilled steep slopes. Runoff transports either topsoil aggregates or parent material particles from the eroded slope sediments. The delivered sediment partly accumulates on the same slope, while the remaining sediment leaves the slope and possibly enters into streams or rivers. The main objective of this study is to survey and to estimate the changes of soil depth on arable land (Outer Somogy, Hungary) during the last 200 years. An additional aim was to compare soil depth changes with microtophography. Soil thickness values show great variations consequently soil types will vary, too. From some regosol spots at least 100 cm soil is gone during approximately 170 years while more then 150 cm thick soil profiles developed not far away. Our results show that the concept of tolerable soil loss as an average value cannot be applied in this case. It is suggested that several individual tolerable soil loss values should be identified for each homogenous unit. The authors suppose the importance of periodicity in landform evolution. Under average climatic conditions sheet erosion plays a primary role in soil detachment at the steepest sections (ephemeral gullies). Most of this sediment accumulates on the bottom of the ephemeral gullies where the steepness decreases consequently. In case of storms with extremely high intensity the huge volume of concentrated runoff deeply cuts into the bottom and clears the sediment accumulated there before. Approximately one third of the detached soil leaves the investigated field mainly through ephemeral gullies. Probably these processes can be understood as an analogy of gully erosion taking place in the interglacial periods and sheet erosion characteristic for the glacial periods of the Pleistocene.