It can be explained by the failure criterium (Eq. (3)). equation(3) τf=c+(ρgh−μ)fτf=c+(ρgh−μ)fwhere τf is the failure shear stress of the landslide’s basal sliding surface, c is the cohesive strength of the mobilised material,
ρ is the density of the soil/rock, g is the Earth’s gravitational acceleration, selleck screening library h is the depth of the basal surface, μ is the water pore pressure in the soil/rock and f is the coefficient of friction on the basal surface. The gravitational body force is proportional to the depth (h). For small (and shallow) landslides, the second term of Eq. (3) is small and slope failure is mostly controlled by the cohesive strength. Contrariwise, friction is more important for large (and deep-seated) landslides. Guns and Vanacker (2013) discussed how land cover change induced by human activities can modify soil physical and hydraulic properties, such as rainfall interception, evapotranspiration, water infiltration, soil hydraulic conductivity, root cohesion and apparent cohesion related to suction under unsaturated conditions. By modifying vegetation cover through agricultural practices, humans modify the root cohesion of soil which
controls PCI-32765 ic50 failure resistance of small landslides. This might explain the displacement of the rollover on the landslide distribution as the rollover is suggested to reflect the transition from a resistance controlled by cohesion to a resistance controlled by friction ( Guzzetti et al., 2002). The fact that the rollover here occurs at rather small landslide areas might result from the thin soils developed Resveratrol on meta-volcanic and meta-sedimentary rocks. Our results (Fig. 6A and B) showed that human-induced land cover change is associated with an increase of the total number of landslides and a clear shift of the frequency–area distribution towards smaller landslides. However, the frequency of large landslides is not affected by anthropogenic disturbances,
as the tail of the empirical probability density model fits is not different between the two environment groups. Graphs C and D (Fig. 6) represent the overall geomorphic work realised by the landslides. The area under the curve is a first estimate of the total amount of sediment produced by landslides in each land cover group. In both sites, landslides that are located in anthropogenic environments produce more sediments than landslides in (semi-)natural environments. However, the most effective geomorphic event, i.e. the peak of the graphs C and D (Fig. 6), is smaller in anthropogenic environments. In (semi-)natural environments, the landslides that are geomorphologically most effective are bigger, but less frequent.