Effects of historical land use and land pattern changes on soil erosion – Case studies from Lower Austria and Central Bohemia

This paper addresses changes in land use and in the spatial distribution of land units and their influence on the soil erosion risk in two areas with a different geomorphology and a different historical and political development: an intensively-used lowland agricultural watershed in central Bohemia, Czech Republic, and a partially hilly agricultural and wine-producing municipality in northern Austria. Our analyses sum up the development of these two study sites, on which the forces driving the land use and the land structure differ due to the different political background in the two countries since the World War II. A definition of the landscape structure was obtained for a sequence of historical time horizons, using the best available data sources. The first historical scenario is based on mid-19th century cadastral maps, while the later scenarios are based on aerial photographs. The soil erosion was then estimated by the Universal Soil Loss Equation in a distributed form application, using GIS preprocessing and the USLE2D utility to calculate the LS-factor. Parcel connectivity ranging from 0 to 100% in 25% steps was used for all of the simulated scenarios. The study shows that even if the spatial extent of the agricultural land does not change significantly, the inner organization of the farming blocks can have a strong effect on the risk of soil erosion. The absolute values of the soil loss are affected by the parcel connectivity used, but the trends defined by the landscape layout are obvious throughout the examined reference years nevertheless. The landscape structure and therefore the soil erosion risk is strongly affected by the economic and political situation and related decisions. Agricultural policies set the fundamental principles on which fragmentation is based.