The role of the vineyards on slope stability: a case study from an area susceptible to shallow landslides

Hilly slopes cultivated with vineyards of Oltrepò Pavese (northern Italy) are often affected by rainfall-induced shallow landslides, which cause destruction and loss of the cultivations. The assessment of soil reinforcement of grapevine roots is then fundamental for slope stability analyses. In sites affected by shallow landslides, root density is lower, probably due to the lowest soil permeability. Despite the differences of soil features, type of bedrock, grapevine age and vineyards row orientation, an unique relationship between root diameter and root tensile strength can be identified. The total root reinforcement follows the trend of the root density. Grapevine roots can give a good reinforcement on soil, usually in the first 0.9-1.0 m from ground level.