Simulation of the Parma River blockage by the Corniglio landslide (Northern Italy)

Near the village of Corniglio, in the northern Apennines about 40 km SW of Parma, a big landslide was recently (1994–1996) subjected to reactivation, damaging many buildings and partially obstructing the Parma River. In this work, we have carried out a quantitative analysis of the recent evolution of the landslide with the help of a Geographic Information System (gis), in order to predict the most plausible future developments. Then, various simulations of landslide descent were carried out, and above all, to evaluate the possibility of blockage formation. To this purpose, two computer programs that simulate the material descent through a cellular automata model and define blockage characteristics were written. Many different simulations were carried out, 16 of which are presented here. For each of them, the computer output consists of a table defining the quantity of displaced material, area and volume of the dam and lake and of a map showing the areas involved in the landslide movement and upstream flooding. In order to assess the probability of blockage formation and dam stability, we applied the simulation results to some empirical rules defined by preceding authors through statistical analysis carried out on a high number of analogous phenomena. These rules suggest that it is very unlikely that blockage takes place as the result of very slow landslide velocity, riverbed width and high erodibility of the material. If it were to occur, the size and shape of the dam seem sufficient to guarantee a considerable degree of stability, making a sudden failure improbable.