In the Tuscany region (23,000 km2, Central Italy) landslides triggered by rainfall are a recurring phenomenon. We set up a regional warning system for the occurrence of landslides, based on intensity – duration rainfall thresholds. Since a single regional threshold would be affected by a too large uncertainty, the region was partitioned into 25 alert zones and for each of them an independent set of empirical intensity – duration rainfall thresholds was defined analyzing the rainfall measurements connected to the triggering of 2132 past landslides. Rainfall data were retrieved from a regional network composed by 332 automated rain-gauges. The thresholds were defined with a semiautomatic procedure which avoids subjective interpretation, one of the main recurring drawbacks affecting the definition of empirical thresholds, as much as possible. We also carried out a semiautomatic calibration procedure that makes use of rainfall events that did not result in landslides. The proposed approach minimizes the false alarms, allowing an effective use for civil protection purposes. The same rain-gauge network used for the calibration of the thresholds was integrated in the regional warning system. Each rain gauge provides hourly rainfall measurements and the data are stored on a protected FTP site managed by the Region authority. The same FTP hosts also rainfall forecasts. A specific procedure was programmed in the PHP language in order to continuously access the FTP site, download new data (if present), store them on a MySQL database and update in near real time the rainfall path of each rain-gauge. A WebGIS system based on the OpenLayers technology allows the real time monitoring of all the rain-gauges measurements and forecasts, which are constantly compared with the rainfall thresholds. Depending on the overcoming of the latter, the WebGIS interface uses an intuitive color mapping to provide an overview of the alert level currently associated to every rain gauge or expected in the next hours. By clicking over a rain gauge link, its rainfall path can be visualized and compared with the respective thresholds.
A regional real time landslide warning system based on a set of spatially variable rainfall thresholds / Segoni S.; Battistini A.; Rosi A.; Rossi G.; Catani F.. - STAMPA. - (2011), pp. 179-179. (Intervento presentato al convegno The Second World Landslide Forum - WLF2 tenutosi a Rome, Italy nel 3-9 October 2011).
A regional real time landslide warning system based on a set of spatially variable rainfall thresholds
Segoni S.;Battistini A.;Rosi A.;Rossi G.;Catani F.
2011
Abstract
In the Tuscany region (23,000 km2, Central Italy) landslides triggered by rainfall are a recurring phenomenon. We set up a regional warning system for the occurrence of landslides, based on intensity – duration rainfall thresholds. Since a single regional threshold would be affected by a too large uncertainty, the region was partitioned into 25 alert zones and for each of them an independent set of empirical intensity – duration rainfall thresholds was defined analyzing the rainfall measurements connected to the triggering of 2132 past landslides. Rainfall data were retrieved from a regional network composed by 332 automated rain-gauges. The thresholds were defined with a semiautomatic procedure which avoids subjective interpretation, one of the main recurring drawbacks affecting the definition of empirical thresholds, as much as possible. We also carried out a semiautomatic calibration procedure that makes use of rainfall events that did not result in landslides. The proposed approach minimizes the false alarms, allowing an effective use for civil protection purposes. The same rain-gauge network used for the calibration of the thresholds was integrated in the regional warning system. Each rain gauge provides hourly rainfall measurements and the data are stored on a protected FTP site managed by the Region authority. The same FTP hosts also rainfall forecasts. A specific procedure was programmed in the PHP language in order to continuously access the FTP site, download new data (if present), store them on a MySQL database and update in near real time the rainfall path of each rain-gauge. A WebGIS system based on the OpenLayers technology allows the real time monitoring of all the rain-gauges measurements and forecasts, which are constantly compared with the rainfall thresholds. Depending on the overcoming of the latter, the WebGIS interface uses an intuitive color mapping to provide an overview of the alert level currently associated to every rain gauge or expected in the next hours. By clicking over a rain gauge link, its rainfall path can be visualized and compared with the respective thresholds.
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