A REAL-TIME FORECASTING-MODEL FOR LANDSLIDES TRIGGERED BY RAINFALL

The FLaIR model has been developed for the simulation and the forecast ing of landslide movements activated by rainfall. It is composed of tw o modules. The first, rainfall-landslide module, correlates precipitat ion and landslide occurrence. The second, stochastic rainfall module, provides synthetic generation of rainfalls, giving a probabilistic rep resentation of future precipitations. A mobility function, schematised as convolution of the rainfall intensity and a filter function, is re lated to the probability of landslide occurrence. The forecasting cons ists of the estimation at time tau of the value that the mobility func tion may attain to, at time t. Such a value depends on both the observ ed rainfall intensity, measured before tau, and the estimated one, der ived from the stochastic rainfall module in the interval]tau, t]. Then the mobility function is composed of a deterministic and a stochastic part. In the paper a parameter, variance index, is introduced in orde r to describe the roles of the two components. For two very general cl asses of filters the analytical form of the variance index is determin ed providing an easy evaluation of the weights of the two components. The behaviour of different types of landslides is finally emphasised b y two case studies.