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Debris flows are one of the natural disasters that can occur in the alpine environment, cause large economic damage, and endanger human lives. This study presents an overview of recent research done in relation to the debris flow hazard assessment and conceptual mitigation at the Koroška Bela area in Slovenia. This includes fieldwork, lab experiments, modelling, and a conceptual design of hydro-technical measures to reduce the risk. The results indicate that multiple debris flows occurred in the past in the area but a relatively long period of more than 100 years without an extreme event led to urbanization and development of the area. Magnitudes of the most extreme events as the worst-case scenarios were estimated to be in the range between 100,000 and 400,000 m3, using debris flow modelling and geological information from research trenches. Based on the landslide volumes, such events could also potentially occur in the future in extreme conditions. Additionally, torrential floods could mobilize more than 15,000 m3 of material located along the stream network that can be regarded as potentially unstable. The existing check dam system does not have the capacity to capture this material. Thus, a new check dam and three flexible net barriers could help to reduce the risk due to torrential outbursts or debris flows. [ABSTRACT FROM AUTHOR]

Rainfall-induced landslides are one of the most frequent natural disasters. Detection of changes in the characteristics of the rainfall events that can be regarded as triggering factor is therefore of primary importance for policy-makers, practitioners, civil protection units and others. This study evaluated changes in the frequency and intensity of rainfall events above selected empirical rainfall thresholds at the pan-European level. For areas classified as at least moderately susceptible to landslides according to the ELSUS v2 map (i.e. around 1.8 * 106 km2; around 37% of the area), changes were evaluated for the 1961–2018 period. The regional rainfall reanalysis data was used as input. Four different empirical rainfall thresholds were selected and changes in the frequency of rainfall events above the thresholds and their characteristics were analysed. The results showed that, on average, 14% more rainfall events above the threshold were recorded in the 1991–2018 period compared to 1961–1990 at the European level according to the selected empirical rainfall threshold. Moreover, several regions were found where frequency and intensity of rainfall events above the four selected global empirical rainfall thresholds were positive and statistically significant. These regions were for example Italy, Carpathian Mountains, British Isles and some other parts of Europe. Some of these areas are also regions where landslides susceptibility is high or even very high and where multiple landslides were recorded in the past. On the other hand, there are also regions where frequency and intensity of events above the threshold were negative and statistically significant. These regions were parts of Central Europe, Alps and Pyrenees. Also, in these regions landslides frequently occur. According to different empirical thresholds, no significant change in the frequency of rainfall events above the thresholds could be detected for around 50% of the investigated area. [ABSTRACT FROM AUTHOR]

Highlights from the article: In 2019, the Faculty of Civil and Geodetic Engineering of the University of Ljubljana (UL FGG) is celebrating its centennial: The precursor of the faculty was the Technical Faculty established in 1919 as one of five founding faculties of the university. In the field of capacity building, UL FGG offers several courses for graduate and postgraduate students in landslide mechanics and dynamics, landslide stabilization and landslide risk mitigation. IPL-151 Soil matrix suction in active landslides in flysch - the Slano Blato landslide case (2010-2012) (Mikos et al. [23]; Macek et al. [12]) 31 Pulko B, Majes B, Mikos (2013) Reinforced concrete shafts for the structural mitigation of large deep-seated landslides: an experience from the Macesnik and the Slano Blato landslides (Slovenia).

Further regional and spatial development of the Republic of Slovenia is based on a wide share of protected areas that pose significant demands for spatial planers. As an example of links between spatial planning and management of protected areas, in this paper we deal with the Triglav National Park (TNP) in NW Slovenia, particularly with the proposal for its 2014-2023 management plan and to which extent this plan takes into account specific conditions that arise from risk areas due to natural hazards as a significant water management expert foundation for planning the use of space. The paper explicitly demonstrates that the determination of hazard and risk areas in Slovenia is truly necessary, and that only a detailed determination of hazard and risk areas in scales 1:1000 to 1:5000 makes possible detailed spatial planning and thus also the management of protected areas. From the discussion, it also follows that the proposed TNP management plan should be upgraded in the field of research by establishing a Scientific (research) council at the TNP Administration, and by establishing a specific targeted research program focused on research in TNP. [ABSTRACT FROM AUTHOR]

The paper shows in detail the case of delineation of risk area in the village of Log pod Mangartom in the Koritnica River valley due to possible debris flows that might in future be triggered on the Stože slope above the Mangart Mountain pasture. On the basis of field and laboratory investigations of the debris flow of November 17, 2000, that devastated the Koritnica River valley, the possible scenarios of triggering new debris flows on the Stože slope were investigated. For the determination of debris flow hazard area in the Koritnica River valley, the results of one- and two-dimensional modelling of selected debris flows of known magnitudes and different viscosities were applied. For the determination of risk area, the existing and the possible new infrastructures were taken into account, and the risk area was divided into 3 zones. The paper presents the expert bases summarised by the legislator in the relevant decree issued by the Government of the Republic of Slovenia on the conditions and limitations governing the construction in the debris-flow risk area of Log pod Mangartom. This regulation is the first of its kind in Slovenia. [ABSTRACT FROM AUTHOR]

Landslides are one of the most frequent natural disasters that can endanger human lives and property. Therefore, prediction of landslides is essential to reduce economic damage and save human lives. Numerous methods have been developed for the prediction of landslides triggering, ranging from simple methods that include empirical rainfall thresholds, to more complex ones that use sophisticated physically- or conceptually-based models. Reanalysis of soil moisture data could be one option to improve landslide forecasting accuracy. This study used the publicly available FraneItalia database hat contains almost 9000 landslide events that occurred in the 2010–2017 period in Italy. The Copernicus Uncertainties in Ensembles of Regional Reanalyses (UERRA) dataset was used to obtain precipitation and volumetric soil moisture data. The results of this study indicated that precipitation information is still a much better predictor of landslides triggering compared to the reanalyzed (i.e., not very detailed) soil moisture data. This conclusion is valid both for local (i.e., grid) and regional (i.e., catchment-based) scales. Additionally, at the regional scale, soil moisture data can only predict a few landslide events (i.e., on average around one) that are not otherwise predicted by the simple empirical rainfall threshold approach; however, this approach on average, predicted around 18 events (i.e., 55% of all events). Despite this, additional investigation is needed using other (more complete) landslide databases and other (more detailed) soil moisture products. [ABSTRACT FROM AUTHOR]