Land-Use Change and Shallow Landsliding: A Case History from the Apennine Mountains, Italy

We investigate temporal variations in land use and landsliding in a small catchment characterized by the predominance of clay-rich materials and known to be prone to shallow slope failures. The results demonstrate a pronounced change from land use dominated by grassland pasture (~53 % in 1955) to wheat-based agriculture (~74 % in 2011). The temporal series of landslide inventories also indicate significant variations in landslide activity in the same period. In particular, the highest susceptibility to landsliding has been registered in recent years on the sown fields which had initially (1955) been used for pasture and grazing. The data also reveal that with time the steeper and apparently more landslide-prone slopes with grassland-pasture have been given over to new wheat cultiva- tion. The introduction of ploughing for the new wheat cultivation on the often steep slopes that had originally been covered by grass is considered to be a significant factor in the increased susceptibility to landsliding. The negative impact on slope stability can be related to the decrease in effective strengths of soil resulting from modification of the existing cover from grass that is present all year to wheat characterized by a few month growth period per year, which implies increase in groundwater levels, and mechanical disturbance of soil caused by tillage. Finally, for the studied period (1955-2011) the local precipitation data indicated high inter-annual variability without the presence of any statistically signifi- cant trends.