the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
The alerting system for hydrogeological hazard in Lombardy Region, northern Italy: rainfall thresholds triggering debris-flows and "equivalent rainfall" method
Abstract. The Functional Centre (CFMR) of the Civil Protection of the Lombardy Region, North Italy, has the main task of monitoring and alerting, particularly with respect to natural hazards. The procedure of early warning for hydrogeological hazard is based on a comparison of two quantities: thresholds and rainfall, both referred to a defined area and an exact time interval.
The CFMR studied 52 landslide events (1987–2003) in Medium-Low Valtellina and derived a model of the critical detachment rainfall, in function of the local slope and the Curve Number CN (an empirical parameter related with the land cover and the hydrological conditions of the soil): it's physically consistent and allows a geographically targeted alerting. Moreover, rainfall thresholds were associated with a typical probability of exceedance.
The processing of rainfall data is carried out through the "equivalent rainfall" method, that allows to take into account the antecedent moisture condition of the soil: in fact the hazard is substantially greater when the soil is near to saturation. The method was developed from the CN method and considers the local CN and the observed rainfall of the previous 5 days. The obtained value for the local equivalent rainfall, that combines rainfall (observed and forecasted) and local soil characteristics, is a better parameter for the evaluation of the hydrogeological hazard.
The comparison between equivalent rainfall and thresholds allows to estimate the local hydrogeological hazard, displayed through hazard maps, and consequently to provide a reliable alerting activity (even localized to limited portions of the region).
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RC C48: 'Referee comment', Anonymous Referee #1, 12 Feb 2015
- AC C71: 'Reply to Anonymous Referee #1', Alessandro Cucchi, 23 Feb 2015
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RC C398: 'Review of Manuscript NHESS-269-2015', Anonymous Referee #2, 08 Apr 2015
- AC C420: 'Reply to Anonymous Referee #2', Alessandro Cucchi, 10 Apr 2015
- EC C455: 'Editorial Decision', Fausto Guzzetti, 19 Apr 2015
-
RC C48: 'Referee comment', Anonymous Referee #1, 12 Feb 2015
- AC C71: 'Reply to Anonymous Referee #1', Alessandro Cucchi, 23 Feb 2015
-
RC C398: 'Review of Manuscript NHESS-269-2015', Anonymous Referee #2, 08 Apr 2015
- AC C420: 'Reply to Anonymous Referee #2', Alessandro Cucchi, 10 Apr 2015
- EC C455: 'Editorial Decision', Fausto Guzzetti, 19 Apr 2015
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Cited
3 citations as recorded by crossref.
- Technical Note: An operational landslide early warning system at regional scale based on space–time-variable rainfall thresholds S. Segoni et al. 10.5194/nhess-15-853-2015
- Rainfall and land use empirically coupled to forecast landslides in the Esino river basin, central Italy E. Gioia et al. 10.5194/nhess-15-1289-2015
- The impact of rainfall time series with different length in a landslide warning system, in the framework of changing precipitation trends S. Segoni et al. 10.1186/s40677-016-0057-6