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Natural factors inducing slope instability and erosion in two geographic regions of the Mediterranean basin in Italy and Greece

The project has focused on the study of natural factors related to degradation and erosion of slopes in Italy and Greece. In the Greek area the seismicity is also an additional factor triggering slope instability.

Hierarchical clustering of the results of a principle component analysis of slope degradation susceptibility was used to create terrain units with marked characteristics with respect to slope stability. Susceptibility is defined as contribution of disorder feature density to the considered terrain unit and validated by detailed mapped slope degradation induced by a significant hydrometeorological event. Correspondence analysis of disorder feature density and precipitation density of a significant event showed that precipitation thresholds for slope failure have a significant spatial component, a better understanding of the effects. A constructed lumped hydrological modelling for threshold analysis using multiple boxes shows that groundwater table depth parameter is sufficient to characterize the severity of hydrological events to landsliding. Hydrological modelling is more straightforward in slope degradation threshold analysis than the use of precipitation factors. Synthetic aperture radar (SAR) images differential interferometry (DI) testing found that DI was a possible tool for future large scale slope processes monitoring.

In the course of the project two significant events occurred in both pilot areas. The earthquake of June 1995 in Aegio with magnitude of 6.1 Richter enabled a study to be made of the relationship between faulting and mass movement. The analysis showed that the disorder associated with the earthquake is relatively low compared to others with lower intensity but shallower focal points. The hydrological event of November 1994 in the Langhe demanded new efforts to be made in reconstructing the newly formed slope disorder effects induced and comparing them with soil hydrological conditions. The new information enabled investigation of the relationship between flooding effects produced by the event and the sediment yield in two rivers. The average sediment yield proved to be useful for comparing extreme flood effects and sediment discharge capacity indicated that average sediment yield is composed mainly by sediment yield provided during important events, and that sediment contribution from distinct subcatchments of the main rivers is conservative for different events. Flooding effects proved to be consistent with sediment discharge capacity and sediment yield variation. The method is useful in flooding hazard mapping and regional planning.

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Hydrodata SpA
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