An operational warning system for the forecasting of landslide occurrence at regional scale

In this work we present a regional scale warning system (named SIGMA) for rainfall induced landslides. The system combines rain gauges measurements and rainfall forecasts and compares them with a series of statistical rainfall thresholds based on the total amount of rainfall. The system was specifically built to take into account both shallow and deep seated landslides. A decisional algorithm integrated in the warning system automatically provides a criticality level depending on which thresholds are exceeded. The model was integrated in the regional warning system of the Emilia Romagna region (Italy) for civil protection purposes. This paper accounts also for the main modifications that the model had during its development, passing form a base version relying on thresholds defined by means of a statistical analysis on rainfall data, to an advanced version in which thresholds were calibrated using a landslide database. The passage from a system to another was straightforward and for its flexibility and versatility, the proposed methodology seems particularly appropriate for emerging countries that have not yet gathered extensive and complete information on the location and time of occurrence of landslides.