Influence of land-use change and precipitation patterns on landslide activity in the Daunia Apennines, Italy

The historical variations in landslide activity are investigated in the Rocchetta S. Antonio territory, where sown fields cover 75% of the total area. The perception of the inhabitants is that landsliding has increased in recent years, and climate change has been invoked as a case. However, since 1865 annual precipitation has decreased c. 8% per century in southeastern Italy and local rainfall data for the 1955-2008 period show high inter-annual variability with statistically uncertain trends. In the same decades human alterations to the local environment were considerable. To demonstrate the impacts of land-use changes, detailed landslide and land-use maps spanning the 1976-2006 period have been constructed and the spatial-temporal changes in the context of the local precipitation patterns have been analysed. It is shown that the frequency of landsliding in 2006 was 160% higher than in 1976, even though both years were comparably wet. The sown fields increased by 46% from 1976 to 2006, and the landslide density was 55% higher on the new sown fields; that is, those cultivated after 1976. Thus, the higher susceptibility to landsliding is linked to the land-use changes and especially to the new ploughing for EU-sponsored wheat cultivation that has taken place on the steeper slopes.