Keywords

1 Introduction

1.1 About the Faculty

The Faculty of Civil and Geodetic Engineering of the University of Ljubljana (UL FGG), covering engineering disciplines, including water science and technology, has been involved in landslide risk reduction activities at the national level in Slovenia (former Yugoslavia, until 1991) for decades (eg., Mikoš 2020, 2021). In 2008, UL FGG became an ICL Full Member and has gradually developed its ICL engagement (ICL 2023a). UL FGG has been awarded the title of the World Centre of Excellence (WCoE) in Landslide Risk Reduction for 5 consecutive periods (2008–2011, 2011–2014, 2014–2017, 2017–2020, 2020–2023)—it is now applying as a WCoE for a new period (2023–2026). Together with the Geological Survey of Slovenia, in 2017 UL FGG hosted the 4th World Landslide Forum in Ljubljana, Slovenia.

UL FGG strongly supports diverse activities of the International Consortium on Landslides, Kyoto, Japan, and thus contributes to the 2030 Agenda for Sustainable Development as well as the Sendai Framework for Disaster Risk Reduction 2015–2030 (UNDRR PreventionWeb 2015). UL FGG was a signatory of the Sendai Landslide Partnerships 2015–2030 (Sassa 2015) and is a dedicated Official Promoter of the Kyoto Landslide Commitment 2020 (ICL 2023b), a SF DRR voluntary commitment by ICL. This commitment supports the implementation, follow-up, and review of the Sendai Framework 2015–2030, the UN 2030 Agenda for Sustainable Development, the New Urban Agenda, and the Paris Climate Agreement as it addresses the adverse effects of climate change related to landslides (Sassa 2021a).

In 2016, UL FGG started to host the University of Ljubljana UNESCO Chair on Water-related Disaster Risk Reduction (WRDRR), being still the only UNESCO Chair at this university, and one of a few in Slovenia. Among its activities, in 2022 the WRDRR Chair supported the launching of the regional platform called ResiliEnhance for enhancing the resilience to disasters for sustainable development. UL FGG also supports the activities of the Slovenian National Committee for UNESCO Intergovernmental Hydrological Programme (IHP), now working on the IHP-IX programme (2022–2029).

UL FGG is actively involved in many international (bilateral) and national research projects in the field of hydrology and hydraulic engineering, including topics such as landslide research, landslide risk mitigation, natural risk dialogue, and capacity building for society resilience.

In terms of capacity building, UL FGG offers several courses for graduate and postgraduate students in landslide mechanics and dynamics, landslide stabilization and landslide risk mitigation.

1.2 The Focus of This Article

UL FGG has been a full ICL member since 2008, and it is fully dedicated to the ideals and activities of the ICL, which was recently re-confirmed by being one of the first 2020 KLC signatories (Sassa 2021a).

The article presents a review of research and other activities of UL FGG from early 2020 to mid-2023, which contributed to 2020 Kyoto Commitment for Landslide Risk Reduction—in various ways, including and primarily as a full ICL member and the World Centre of Excellence in Landslide Risk Reduction 2020–2023.

2 WCoE (2020–2023) Landslides in Weathered Heterogeneous Sedimentary Rock Masses Such as Flysch

The World Centre of Excellence in Landslide Risk Reduction at the University of Ljubljana, Slovenia, was confirmed during the 5th World Landslide Forum in Kyoto, Japan, as a prolongation of the WCoE 2017-2020 entitled “Landslides in Weathered Flysch: From Activation to Deposition” (Mikoš et al. 2021a), and had the following two objectives:

  1. (i)

    The main scientific aim will be to study weathering processes of heterogeneous sedimentary rock masses such as flysch bedrock both in laboratory (using standard tests) and on-site (using remote sensing techniques on different landslides in flysch).

  2. (ii)

    Enhancement of landslide science in the Adriatic-Balkan Region through capacity development at the regional level as an outcome of regional scientific and high-education projects and cooperation.

2.1 Laboratory Research

Laboratory research is also needed to collect relevant input data for different kinds of models and to investigate landslide dynamics. In recent years, we have investigated rheology characteristics of natural debris material from different landslides (Fig. 1) (Bezak et al. 2021a; Jurček 2020; Jurček et al. 2022). As an example, in the scope of the study conducted by Jurček et al. (2022), the rheological parameters were measured at different sediment concentrations using two shear-rate controlled coaxial cylinder rheometers (Brookfield DV3T HB and ConTec Viscometer 5) and standard tests for determining the workability and flowability of construction materials (e.g., funnels, V-funnel, flow channel, flow table, L-box). The measured data were evaluated by using the Bingham rheological model. The study conducted by Jurček et al. (2022) showed that the rheological parameters measured with the coaxial cylinder rheometers give reasonably good predictions of standard test results, while vice versa, i.e., from these standard tests estimation of rheological parameters is not possible. Additionally, the results of laboratory small-scale experiments were also used to evaluate the performance of multiple hydrological rainfall loss methods (Bezak et al. 2022a). The results of the previously mentioned study showed that the initial parameters of the rainfall loss model can satisfactorily reproduce the experimental results in some cases (Bezak et al. 2022a). Despite the fact that the slope material characteristics used in the laboratory experiments were relatively homogenous, some well-known methods yielded inaccurate results (Bezak et al. 2022a). Hence, this indicated the importance of model calibration.

Fig. 1
A scatter plot depicts the yield strength and plastic viscosity versus sediment concentration. The different symbols of Bingham model parameters plot the distribution of data points with an increasing trend, reaching a maximum strength of 1000 pascals.

Bingham model parameters of samples from the Urbas (U), Čikla (Č), and Stože (S) landslides. The results are compared from the literature data (K—Kaitna et al. (2007) & B—Bisantino et al. (2010)) (Source: Fig. 6 from Bezak et al. (2021a))

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Coarse (and fine) rock or debris particles are subjected to abrasion (wearing away) during their routing in sedimentary environments, leading to mass loss and changes in the particles’ morphology (Mikoš and Jaeggi 1995). The particles become more spherical, rounded, and smooth, as determined using dynamic image analysis of particles (Kuzmanić and Mikoš 2022a, b). Such processes cover fluvial processes, as well as gravitational processes, including mass movements. Different-energy-level abrasion in Los Angeles and Micro-Deval apparatuses was compared using mass loss and rounding of sediment particles as a proxy for natural processes in the field (Kuzmanić et al. 2023). Los Angeles (high-energy) abrasion resulted in higher mass loss values than micro-Deval (low-energy) abrasion. The mass loss results can be brought to comparable values by a newly introduced mass- and power-dependent coefficient. Low-energy abrasion resulted in faster rounding than high-energy abrasion, whereas the form stayed nearly the same. In contrast, the form changed rapidly during high-energy abrasion.

The ongoing extensive testing of gravel-sized granular material aims to recognize and evaluate the effect of naturally occurring freezing and thawing cycles on the abrasion characteristics of such natural materials in different granulometric and energetic conditions. Laboratory investigation on flysch material was conducted within the scope of a national project J1-2477 “Erosional processes on coastal flysch cliffs and their risk assessment”. Flysch samples from different locations on the Slovenian coastal cliffs were subjected to cyclical wetting and drying in a slake-durability apparatus to compare the durability properties of flysch material. The testing was conducted using a standardized procedure, with additional slaking cycles (up to five cycles—Id5). Flysch samples were also tested using the Leeb hardness tester, to compare the material hardness between sampling locations and identify the weaker cliff locations. For these laboratory tests, only preliminary results have been obtained so far.

2.2 Field Research

In order to detect mechanisms of landslides and their dynamics detailed geological, geotechnical, geodetic, and remote sensing investigations and field research is needed (Mikoš 2020). A case study in the Koroška Bela area, NW Slovenia, was conducted, where the Urbas landslide has been investigated for years (e.g., Bezak et al. 2021a; Peternel et al. 2022a, b, c). Recently it was found that the Urbas landslide dynamics (Figs. 2 and 3) differs along the landslide area and depends on local geological and hydrogeological conditions (Peternel et al. 2022a, b, c).

Fig. 2
A schematic depicts the cross-section of the Urbas landslide with elevation and horizontal distance. The sliding surface exhibits geological boundaries, carbonate gravel and rocks, dolomite, clastic rocks, fine-grained rocks, inclinometer, and piezometer. A line graph of depth versus displacement.

A cross-section along the Urbas landslide with data overview showing geological and hydrogeological settings, cumulative surface displacements obtained from GNSS, in situ object-point geodetic measurements, and deep displacements obtained by the inclinometer (Source: Fig. 5 from Peternel et al. (2022b), CC BY 4.0)

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Fig. 3
4 images. A. An orthophoto of a steep slope with a landslide. B to D. 3-D photogrammetry categorizes digital elevation model difference values into different ranges representing erosion, no change, and accumulation. These ranges start from less than negative 1 meter to greater than 1 meter.

(a) Orthophoto of a steep slope above the Urbas landslide obtained by unmanned aerial vehicle (UAV) photogrammetry in May 2020; (b) DEM difference (DoD) between August 2019 and May 2020; (c) DEM difference (DoD) between May 2020 and August 2020; (d) DEM difference (DoD) between August 2019 and August 2020 (Source: Fig. 9 from Peternel et al. (2022b), BB CY 4.0)

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In recent years, field research also focused on in-depth investigation related to the triggering of rockfalls in eastern Slovenia (Jemec Auflič et al. 2022)—as a result of the project entitled “Deciphering the sensitivity of rock faces to climatic changes and freeze-thaw cycles in permafrost-free regions” (IPL-262 project, Geological Survey of Slovenia, with UL FGG collaboration, 2022–2024).

Another detailed field study was undertaken in the torrential area upstream of the Krvavec ski resort, NW Slovenia, where a short but extreme debris flood occurred in 2018 (Bezak et al. 2020). In order to protect the ski lift cabin car, several mitigation measures were planned, some of which have already been implemented. The mitigation includes the restoration of local streams, the construction of a large slit check dam for sediment retention, the construction of several smaller check dams and the construction of multiple flexible net barriers for controlling in-channel erosion in steep torrential streams.

Moreover, to observe and monitor potential future extreme events, an extensive monitoring system has been established in the investigated area, including measurements of flexible nets’ corrosion, estimation of concrete abrasion at check dams, periodical geodetic surveys using small drones (UAV), hydro-meteorological measurements using rainfall gauges and water level sensors. A video recording system will be established for closer observation of future disaster events (Sodnik and Mikoš 2022a, b). The project is still in its starting phase.

2.3 Numerical Modelling Studies

Several modelling studies have also been conducted in recent years, where RAMMS model has been used for modelling debris floods and debris flows (Fig. 4) (Bezak et al. 2020, 2021a).

Fig. 4
Two hydrographs of the Urbas landslide exhibit the debris flow, with height and velocity highlighted in colors. The color gradient scale for the maximum height ranges from 0 to 10.93, and the maximum velocity ranges from 0 to 21.64.

A typical RAMMS modelling result for the Urbas landslide (Koroška Bela Municipality, Slovenia) in a case of potential debris flow triggering. Maximum debris flow height and velocity are shown. Results using μ = 0.075 and ξ = 200 m/s2 and a hydrograph volume of 200,000 m3 and a peak discharge of 2680 m3/s are presented (Source: Fig. 2 from Mikoš and Bezak (2021), CC BY 4.0)

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Bezak and Mikoš (2021) also conducted a review of different RAMMS model applications in the Alpine environment. Based on the review conducted, it is clear that RAMMS parameter ranges were relatively wide, and model calibration using debris-flow post-event survey field data is the essential step that should be done before applying the RAMMS model. However, an overview of the parameters can help to limit the parameter ranges. Particularly when considering the similarity between relevant case studies conducted in similar environments.

Additionally, modelling and classification of alluvial fans with DEMs were done using different machine learning algorithms (Babič et al. 2021)—as a result of the project entitled “Recognition of potentially hazardous torrential fans using geomorphometric methods and simulating fan formation” (IPL-225 project, UL FGG 2017–2020).

2.4 Large-Scale Studies

Additionally, in recent years several large-scale studies have also been conducted ranging from an analysis of freeze-thaw cycles in Slovenia (Mikoš et al. 2022) to an investigation of rainfall events above empirical rainfall thresholds in Europe (Bezak and Mikoš 2021). While Bezak et al. (2022b) prepared a review of recent research in this field, Mikoš et al. (2022) investigated the rock frost weathering and rockfall activity in Slovenia and tested several different rockfall susceptibility models. It was found that slope and lithology are the two factors that significantly affect the model performance. On the other hand, some other input data such as the seismic-hazard map had a smaller impact on the model performance (Mikoš et al. 2022).

Bezak et al. (2021b) investigated the performance of reanalysis of soil moisture data for the prediction of landslides in Italy. It was found that at such large-scales precipitation is a better predictor of landslide activity (Bezak et al. 2021b).

Bezak and Mikoš (2021) found that around 15% more rainfall events were detected above the selected empirical rainfall thresholds, as recently compared to the past period of around 1961, meaning that the frequency of landslides in Europe could increase.

Several studies have investigated rockfall activity in flysch formations in Slovenian Istria (Verbovšek et al. 2021, 2022). In 2023, a regional rockfall hazard map for the coastal area of Slovenia is under preparation, which will take into account field geological data, meteorological data (air temperature, wind velocity and direction, precipitation), sea wave characteristics, etc. The map will be prepared using different methodological steps and validation will be performed using field surveys.

3 IPL-261 World-Wide-Web-Based Landslide Observatory (W3bLO) (2022–2024)

This is a joint project of the University of Ljubljana (UL FGG and UNESCO Chair on Water-related Disaster Risk Reduction) and the International Research Centre on Artificial Intelligence at the Jožef Stefan Institute under the auspices of UNESCO, all in Ljubljana, Slovenia. The main project field of development is in technical development.

A web-based Landslide Observatory will be developed, capable of collecting/presenting nearly now-cast information on the present status of selected indicators relevant for landslide risk reduction at the global scale, based on the EU project NAIADES (2022). For its development, Artificial Intelligence (AI) techniques (e. g. Deep Learning, and other algorithms) and selected large databases with data from the public domain will be applied (NAIADES Water Observatory 2023). The observatory is a first step towards building a Digital Twin of Landslide Risk Assessment. The study area is the global scale using different on-line satellite data (i.e., Sentinel) and large web databases. In 2022, the methodology was tested on selected natural hazards (floods & heat waves) that offered enough social media and news information to be analyzed using available text-mining tools (Mikoš et al. 2023a, b).

The planned project activities were submitted to the Open-Ended Working Group for operationalization of the IXth programme of the Intergovernmental Hydrological Programme of UNESCO (2022). The next steps will be: i) the Development of AI tools and techniques to be used for Landslide Observatory, ii) Building up the observatory using available and curated open datasets and filtered news feeds.

The methodology will be tested in Slovenia and elsewhere, where publicly available databases in different languages can provide sufficient data for validation. Thus, other ICL members will be invited to support the development in its second phase to provide data, and test the observatory in their country and language. After the final inauguration of the observatory, the general public and experts worldwide will be able to use it to plan prevention measures to mitigate and reduce landslide risk at regional and local scales.

4 Other ICL/IPL Activities at UL FGG

UL FGG served the ICL by taking different leading roles in the Consortium, for example, a UL FGG member served as Chair of IPL Evaluation Committee, twice as ICL Vice President, and was elected to Co-Chair and in 2021 to Chair of the Global Promotion Committee of IPL-KLC (https://www.landslides.org/ipl-info/ipl-klc-globalpromotion-committee/).

UL FGG has been strongly supporting the journal Landslides: Journal of the International Consortium on Landslides, published by Springer Nature (https://link.springer.com/journal/10346) since its launch in 2004 (Mikoš et al. 2021b). UL FGG works for the journal in the roles of reviewers and an associate editor, and regularly publishes its top research results in the journal (e.g., Bezak et al. 2020, 2021a, b; Bezak and Mikoš 2021) as well as disseminates information important for capacity building in landslide risk reduction—such as results of bibliometric studies on the journal Landslides and ICL books.

Since 2022, UL FGG has contributed several articles to the newly introduced open-access book series “Progress in Landslide Research and Technology” (Sassa 2021b):

  • an introductory article on the new book series (Sassa and Mikoš 2023),

  • a review article on the history of the International Programme on Landslides (IPL) (Mikoš et al. 2023a),

  • an original article on the natural-hazard-related web observatory as a sustainable development tool (Mikoš et al. 2023b),

  • an original article on landslide research and technology in patent documents (Mikoš 2023a),

  • an original article on landslide research and technology in international standards (Mikoš 2023b),

  • an original article on landslides in higher education curricula and beyond (Mikoš 2023c),

  • a review article on UL FGG contributions to the 2020 KLC Commitment (this volume)

5 University of Ljubljana UNESCO Chair on Water-related Disaster Risk Reduction (2016–2020 and 2020–2024)

Much landslide-related research and capacity building for sustainable development and society resilience is underpinned by the UNESCO Chair on Water-Related Disaster Risk Reduction at University of Ljubljana.

5.1 About the Chair

Experiences and knowledge accumulated in the past decades at the Chair on Hydrology and Hydraulic Engineering at UL FGG in the field of (applied) hydrology in experimental basins, hydraulic engineering, landslide research, landslide risk reduction, and flood risk management culminated in 2016 in the establishment of the UNESCO Chair on Water-related Disaster Risk Reduction (WRDRR Chair 2023) at the University of Ljubljana. The UNESCO WRDRR Chair was positively evaluated by UNESCO in 2020 and prolonged for another 4 years (2020–2024). The Chair is associated with the university twinning and networking UNITWIN UNESCO—Kyoto University—ICL on “Landslide and Water-Related Disaster Risk Management”.

The UNESCO WRDRR Chair is involved in many international (bilateral) and national research projects (for a list see: https://www.unesco-floods.eu/). Their results are timely reported in the scientific literature (https://www.unesco-floods.eu/category/publications/).

5.2 ULTRA Project: University of Ljubljana Sustainable Development Pilot Projects (2022–2025)

In 2022, the UNESCO Chair started to head one of the University of Ljubljana pilot projects on Sustainable Development (2022–2025; www.unesco-floods.eu/ultra-pilot-projects/) to modernize university professional study programmes, especially in civil engineering, and to increase students’ competences for sustainable development, including disaster risk reduction and capacity and resilience building.

5.3 ResiliEnhance Program and Platform

In 2022, the UNESCO WRDRR Chair supported the launching the ResiliEnhance Platform to enhance resilience to disasters for sustainable development (CEI 2022). The platform is part of the ResiliEnhance Program that is at the moment geographically focused on Central and Eastern Europe (SPRINT 2022), and supported by the Central European Initiative (CEI)—a regional intergovernmental forum of 17 Member States in Central, Eastern and South-Eastern Europe—it fosters European integration and sustainable development through regional cooperation and its work is focused on achieving two main goals: Green Growth & Just Societies.

The ResiliEnhance program is currently launching an expert platform to explore effective ways and means for strengthening territorial resilience to adverse events and critical situations in the context of complexity and systemic risk. The model for this new platform is the one of the Global Alliance for Disaster Risk Reduction & Resilience in the Education Sector (GADRRRES 2023). GADRRRES is a multi-stakeholder platform comprised of UN agencies, international non-governmental agencies, leading humanitarian and development organizations, private sector organizations, and similar regional alliances.

UNESCO WRDRR Chair is supporting these activities another UNESCO Chair on Intersectoral Safety for Disaster Risk Reduction and Resilience, University of Udine, Italy. The ResiliEnhance platform will also be included in the newly launched (first meeting was in July 2023) interactive platform for regional cooperation of the UNESCO Science-related Chairs and Centres in South East Europe—an initiative supported by the UNESCO Regional Bureau for Science and Culture in Europe, Venice, Italy, and agreed during their first meeting on October 26–28, 2022 (UNESCO Venice 2022). UNESCO WRDRR Chair was one of the 28 UNESCO Science-related Chairs and Centres from 8 countries that adopted the Palazzo Zorzi Declaration.

All this networking in the region will help increase the UNESCO WRDRR Chair’s visibility, while its activities in the field of disaster risk reduction for sustainable development, including landslide risk reduction, will get more international attention, also for the International Consortium on Landslides.

5.4 IHP-IX Program (2022–2029)

UL FGG has supported the activities of the Slovenian National Committee for UNESCO Intergovernmental Hydrological Programme (NC IHP 2023) for many years, hosting it at the Faculty of Civil and Geodetic Engineering, University of Ljubljana. The focus of the activities is the development of the IHP-IX Programme (2022–2029).

The Intergovernmental Hydrological Program and its ninth phase (IHP-IX) have defined 5 priority areas (or streams of action) (UNESCO 2022):

  1. 1.

    Scientific Research and Innovation

  2. 2.

    Water Education for the Fourth Industrial Revolution including Sustainability

  3. 3.

    Bridging the data and knowledge gaps

  4. 4.

    Integrated and Inclusive Water Resources Management under conditions of global change

  5. 5.

    Water Governance based on science for mitigation, adaptation and resilience

The UNESCO WRDRR Chair as a member of the ICL will contribute to the following proposed activities, being defined by the Operational Implementation Plan for IHP-IX (UNESCO 2023):

  • Priority 1.5—Undertaking and sharing assessments on the interaction between humans and water, in line with socio-hydrology by the scientific community supported to develop adaptive pathways, scenarios and strategies for water management.

    Activity: Contribution to research, knowledge generation and dissemination on socio-hydrology, including socio-hydrogeology, as a follow-up of the Panta Rhei decade and previous IHP initiatives in partnership with IAHS.

    WRDRR contribution: Course on Socio-hydrologic assessment of flood protection (5 ECTS) - coursebook

  • Priority 1.6—Scientific knowledge, methodologies and tools in addressing water-related disasters, such as flood and drought elaborated and/or enhanced towards timely forecasting.

    Activity: Research and knowledge generation on the scientific advances in addressing and timely forecasting of water-related disasters, such as (flash) floods, (flash) droughts and rainfall-induced landslides; and on additional impact of synchronous and/or cascading water-related hazards, in partnership with EGU, AGU, IAHS, ISEH and ICL—International Consortium on Landslides and IPL—International Programme on Landslides, including good practices and lessons learned.

    ICL/IPL contributions: journal Landslides, P-LRP book series, World Landslide Forums

  • Priority 2.3—Teaching and learning materials on water-related matters for formal, non-formal and informal education at all levels elaborated towards a better understanding of the importance of water in lives and communities.

    Activity: Development of a series of modules, using the available new technologies and innovative learning processes, based on the existing material and developing new learning material and tools catering to the priorities and needs of the Member States and partners, including the development of a multilingual glossary on water, Case Studies in Socio-Hydrology; Compendium of Case Studies; and custom-made module together with, and for use by, Pan African Virtual and E-University (PAVEU).

    WRDRR contribution: Leading the development of a multilingual glossary on water.

The Implementation Plan for IHP-IX is continuously developing and is monitored by the IHP Secretariat in UNESCO Headquarters, Paris.

6 Conclusions

UL FGG, as one of the World Centres of Excellence in Landslide Risk Reduction, hosts the UNESCO Chair on Water-Related Disaster Risk Reduction. It strongly supports ISDR-ICL Sendai Partnerships 2015–2025 for global promotion of understanding and reducing landslide disaster risk, and its extension to 2030 and beyond: the Kyoto 2020 Commitment for Global Promotion of Understanding and Reducing Landslide Disaster Risk, which was signed in November 2020. UL FGG is proud to be its Official Promoter and will specifically work for Actions 2, 5, 6, 9, and 10.

The worldwide landslide community is invited to support the efforts for society’s resilience against landslides by intensifying their efforts for capacity building in parallel to their research activities. For the International Consortium on Landslides, the KLC 2020 Commitment for Global Promotion of Understanding and Reducing Landslide Disaster Risk (Sassa 2021a) is a standing support and reminder to be active (also) in the field of capacity building, not only through research but also education.

The ICL activities are supporting the implementation of the ninth phase of the UNESCO Intergovernmental Hydrological Programme (IHP-IX) 2022–2029 (UNESCO 2023).