High-resolution reconstruction of a 1300 year old gully system in northern Bavaria,Germany: a basis for modelling long-term human-induced landscape evolution

Knowledge of historical gullying and long-term processes of interactions between land use and gullying is still rather limited. Here, I review results from case studies in Germany and neighbouring countries and exmine the complex development of a gully system in northern Bavaria, integrating land-use changes and their interactions within a conceptual model. Reconstructions of gully development were made by identifying and dating sediment layers, artificial modifications and soil horizons at high spatial and temporal resolution, combined with analyses of historical documents. The case study in northern Bavaria shows that more than 150 colluvial layers found in a gully system revealed the detailed history of gully development during the last 1300 years. The first gullying took place in early Mediaeval times during several heavy rainfall events but the main phases of gullying took place between the fourteenth and the mid-eighteenth centuries. Occurrence of gullying was strongly linked to phases of high land-use intensity, which later changed the runoff pattern and enlarged the catchment area by 50%/o. Subsequently, overflowing field furrows led to the development of two gullies, up to 6 m deep, in late Mediaeval and early modern times. From the middle of the nineteenth century until today, only a little soil erosion has taken place and most of the catchment area has become grassland or forest. During the 1050 years from AD 800 to 1850, a soil volume of about 6430 m³ was eroded by gullying, destroying 15% of the arable land. The results provide a basis for modelling long-term human-induced landscape evolution.