Papers by Francesca Ardizzone
Geomorphology, 2006
We present a landslide susceptibility model for the Collazzone area, central Italy, and we propos... more We present a landslide susceptibility model for the Collazzone area, central Italy, and we propose a framework for evaluating the model reliability and prediction skill. The landslide susceptibility model was obtained through discriminant analysis of 46 thematic environmental variables and using the presence of shallow landslides obtained from a multi-temporal inventory map as the dependent variable for statistical analysis. By comparing the number of correctly and incorrectly classified mapping units, it is established that the model classifies 77.0% of 894 mapping units correctly. Model fitting performance is investigated by comparing the proportion of the study area in each probability class with the corresponding proportion of landslide area. We then prepare an ensemble of 350 landslide susceptibility models using the same landslide and thematic information but different numbers of mapping units. This ensemble is exploited to investigate the model reliability, including the role of the thematic variables used to construct the model, and the model sensitivity to changes in the input data. By studying the variation of the model's susceptibility estimate, the error associated with the susceptibility assessment for each mapping unit is determined. This result is shown on a map that complements the landslide susceptibility map. Prediction skill of the susceptibility model is then estimated by comparing the forecast with two recent event inventory maps. The susceptibility model is found capable of predicting the newly triggered landslides. A general framework for testing a susceptibility model is proposed, including a scheme for ranking the quality of the susceptibility assessment.
Geomorphology, 2005
We propose a probabilistic model to determine landslide hazard at the basin scale. The model pred... more We propose a probabilistic model to determine landslide hazard at the basin scale. The model predicts where landslides will occur, how frequently they will occur, and how large they will be. We test the model in the Staffora River basin, in the northern Apennines, Italy. For the study area, we prepare a multi-temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999. We partition the basin into 2243 geo-morpho-hydrological units, and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables, including morphological, lithological, structural and land use. For each mapping unit, we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period. Assuming that landslide recurrence will remain the same in the future, and adopting a Poisson probability model, we determine the exceedance probability of having one or more landslides in each mapping unit, for different periods. We obtain the probability of landslide size by analysing the frequency-area statistics of landslides, obtained from the multi-temporal inventory map. Assuming independence, we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size, of landslide temporal occurrence and of landslide spatial occurrence. D
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Papers by Francesca Ardizzone