CLIMATE CHANGE IMPACT AND LONG-TERM LANDSLIDES EVOLUTION: A KEY FOR HAZARD PRONE AREAS REGIONALIZATION

G. Delmonaco (ENEA CR Casaccia, CP 2358, 00100 Roma, Italy)
C. Margottini (ENEA CR Casaccia, CP 2358, 00100 Roma, Italy)
S. Serafini (ENEA CR Casaccia, CP 2358, 00100 Roma, Italy)
A. Trocciola (ENEA CR Casaccia, CP 2358, 00100 Roma Italy)

Climatic changes have largely influenced human activities and the features of the territory through the occurrence, for instance, of severe extreme events. Landslides occurrence, in most cases, are triggered by very intense or prolonged rainfalls so that precipitation inducing landslides have been investigated wordlwide, even if the mechanism of transferring the effective precipitation to pore pressure is very complex and still to be exhaustively investigated and understood. The above process is also affected by climate changing due to the variability of amount and pattern of precipitation in long time trends.

A CEC project (EV5V-CT92-0180), in this context, tries to provide, firstly, a methodological approach aimed to a reconstruction of the landslide history since 1000 b.C. in the Euro-Mediterranean region and to the identification of climatic and meteorological factors which may influence and trigger slope instability.

The Central Italy case study (medium Tiber valley), through historical investigation and chronological distribution of extreme natural events in the last millennium, instrumental records since 1.782, dendrogeomorphological data, may provide an useful example for understanding how the variation of meteo-climatic conditions of a territory may change the possibility of occurrence of geomorphic phenomena. The geomorphological evolution of landslides occurrence in the three main historical sites of the area (538 individual events affecting Orvieto, Todi and Civita di Bagnoregio since 1.000 A.D.) allows as well, the possibility to detect the role and the influence of anthropization on the territorial evolution with respect to the impact of hydrogeological hazards in the past and today.

The comparison between landslides evolution and meteo-climatic scenarios highlights the essential role of slide typology on the identification of rainfall thresholds and the possibility of zoning the territory in homogeneous lito-morpho-climatic units.