Basic features of the predictive tools of early warning systems for water-related natural hazards: examples for shallow landslides

To manage natural risks, an increasing effort is being put in the development of early warning systems, which rely on prompt forecasting or recognizing of the catastrophic phenomena and temporarily reducing the exposure of people, preventing or limiting victims. Research efforts aimed at the development and implementation of effective EWS should concern, above all, the definition and calibration of the interpretative model. This paper analyses the main features characterizing predictive models working in early warning systems, by discussing their aims, the evolution stage of the phenomenon where they should be incardinated, and their architecture, regardless of the specific application field. With reference to two different phenomena, namely flow-like landslide and earth flows, both characterized by rapid evolution, the paper describes, by means of three examples, some alternative approaches to the development of the predictive tool and to its implementation in an EWS.