Eighty Years of Data Collected for the Determination of Rainfall Threshold Triggering Shallow Landslides and Mud-Debris Flows in the Alps

Abstract

Identifying the minimum rainfall thresholds necessary for landslides triggering is essential to landslide risk assessment. The Italian Alps have always been affected by shallow landslides and mud-debris flows, which caused considerable damage to property and, sometimes, casualties. We analysed information provided from different sources carrying on the most thorough research conducted for this alpine area. Thousands of documents and reports of rainfall values recorded over 80 years by rain gauges distributed in Sondrio and Brescia Provinces define the mean annual precipitation (MAP)-normalized intensity–duration thresholds for the initiation of shallow landslides and mud-debris flows. The established curves are generally lower compared to those proposed in literature for similar mountain areas in Italy and worldwide. Furthermore, we found that landslides occurred primarily at the same time or within 3 h from the maximum peak of rainfall intensity in summer events and in a period from 0 to 5 h or later in spring-autumn events. The paper provides a further contribution to the knowledge framework on the rainfall conditions required for the initiation of surficial landslides and mud-debris flows and their expected timing of occurrence. This knowledge is crucial to develop better warning strategies to mitigate geo-hydrological risk and reduce the socio-economic damage.

Worldwide Research Trends in Landslide Science

“…In addition, the geomorphological, tectonic and hydrodynamic processes involved in mass movement processes were explained in detail [ 127 , 128 ]. Different experimental research was conducted considering the pressure of the pore fluid, type of grain, rainfall and a large amount of on-site and laboratory investigations, assuring the validity of the results [ 129 , 130 , 131 , 132 , 133 , 134 ].…”

Weather Simulation of Extreme Precipitation Events Inducing Slope Instability Processes over Mountain Landscapes

“…Moreover, the application of the data coming from the applied WRF model, set with the tested parameters, specific for this kind of terrain, could be an aid within the early warning procedures related to the incoming possibility of specific meteorological events potentially triggering instability events in sensitive areas, like the analysed hydrographic basin. In this context, geological and geomorphological analyses and maps [40] surely contribute to improving knowledge useful to understand the environmental responses to heavy rains better (e.g., rainfall thresholds triggering debris flows; [23,59]) and to investigate hazard and risk scenarios. Moreover, reliable meteorological conditions forecast, together with simplified geomorphological maps and sketches (e.g., Geobox, [2]), could help in spreading knowledge for local management purposes, favouring practices of usable science aimed at mitigating risk scenarios [60].…”

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“…Klimatolojik olaylar ile kütle hareketleri arasında bir korelasyon vardır. Sıcaklık ve yağış etkisi, bölgede hâkim olan jeolojik yapı ve arazi eğimi gibi etkenler heyelan oluşum süreçlerinde etkili rol oynamaktadırlar [29]. Meteorolojik karakterli afetlerin mevsimsel dağılımları incelendiğinde, heyelanların yağışın fazla olduğu ilkbahar ve sonbahar mevsimlerinde meydana geldiği ifade edilmiştir.…”