Investigating causal factors of shallow landslides in grassland regions of Switzerland

Abstract. Mountainous grassland slopes can be severely affected by soil erosion, among which shallow landslides are a crucial process, indicating instability of slopes. We determine the locations of shallow landslides across different sites to better understand regional differences and to identify their triggering causal factors. Ten sites across Switzerland located in the Alps (eight sites), in foothill regions (one site) and the Jura Mountains (one site) were selected for statistical evaluations. For the shallow-landslide inventory, we used aerial images (0.25 m) with a deep learning approach (U-Net) to map the locations of eroded sites. We used logistic regression with a group lasso variable selection method to identify important explanatory variables for predicting the mapped shallow landslides. The set of variables consists of traditional susceptibility modelling factors and climate-related factors to represent local as well as cross-regional conditions. This set of explanatory variables (predictors) are used to develop individual-site models (local evaluation) as well as an all-in-one model (cross-regional evaluation) using all shallow-landslide points simultaneously. While the local conditions of the 10 sites lead to different variable selections, consistently slope and aspect were selected as the essential explanatory variables of shallow-landslide susceptibility. Accuracy scores range between 70.2 % and 79.8 % for individual site models. The all-in-one model confirms these findings by selecting slope, aspect and roughness as the most important explanatory variables (accuracy = 72.3 %). Our findings suggest that traditional susceptibility variables describing geomorphological and geological conditions yield satisfactory results for all tested regions. However, for two sites with lower model accuracy, important processes may be under-represented with the available explanatory variables. The regression models for sites with an east–west-oriented valley axis performed slightly better than models for north–south-oriented valleys, which may be due to the influence of exposition-related processes. Additionally, model performance is higher for alpine sites, suggesting that core explanatory variables are understood for these areas.

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AI-Based Susceptibility Analysis of Shallow Landslides Induced by Heavy Rainfall in Tianshui, China

Remote Sensing ◽

10.3390/rs13091819 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1819

Author(s):

Tianjun Qi ◽

Yan Zhao ◽

Xingmin Meng ◽

Guan Chen ◽

Tom Dijkstra

Keyword(s):

Machine Learning ◽

Landslide Susceptibility ◽

Heavy Rainfall ◽

Human Life ◽

Relative Weight ◽

Shallow Landslides ◽

Mitigation Measures ◽

Slope Aspect ◽

Economic Damage ◽

Geological Conditions

Groups of landslides induced by heavy rainfall are widely distributed on a global basis and they usually result in major losses of human life and economic damage. However, compared with landslides induced by earthquakes, inventories of landslides induced by heavy rainfall are much less common. In this study we used high-precision remote sensing images before and after continuous heavy rainfall in southern Tianshui, China, from 20 June to 25 July 2013, to produce an inventory of 14,397 shallow landslides. Based on the results of landslide inventory, we utilized machine learning and the geographic information system (GIS) to map landslide susceptibility in this area and evaluated the relative weight of various factors affecting landslide development. First, 18 variables related to geomorphic conditions, slope material, geological conditions, and human activities were selected through collinearity analysis; second, 21 selected machine learning models were trained and optimized in the Python environment to evaluate the susceptibility of landslides. The results showed that the ExtraTrees model was the most effective for landslide susceptibility assessment, with an accuracy of 0.91. This predictive ability means that our landslide susceptibility results can be used in the implementation of landslide prevention and mitigation measures in the region. Analysis of the importance of the factors showed that the contribution of slope aspect (SA) was significantly higher than that of the other factors, followed by planar curvature (PLC), distance to river (DR), distance to fault (DTF), normalized difference vehicle index (NDVI), distance to road (DTR), and other factors. We conclude that factors related to geomorphic conditions are principally responsible for controlling landslide susceptibility in the study area.

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How far from the road should land cover be assessed? A case study on mesopredator mortality on roads

European Journal of Wildlife Research ◽

10.1007/s10344-021-01461-x ◽

2021 ◽

Vol 67 (2) ◽

Author(s):

Angelika Nieszała ◽

Daniel Klich

Keyword(s):

Land Cover ◽

Red Fox ◽

Home Range Size ◽

Buffer Size ◽

Local Conditions ◽

Explanatory Variables ◽

The Road ◽

Spatially Correlated ◽

European Badger ◽

The Impact

AbstractThe methods used to assess the significance of land cover in the vicinity of a road for the mortality of mesopredators are diverse. In assessing the effect of land cover along the road on road causalities, scientists use various buffer sizes, or even no buffer along the road. The aim of this study was to verify how results of land cover effects on the mortality of mesopredators on roads may differ when analyzing various buffer sizes from the road. We assessed road causalities in the Warmian-Masurian voivodeship (Poland) from 3 consecutive years: 2015, 2016, and 2017. The roads were divided into equal sections of 2000 m each with buffer size of radius: 10, 250, 500, and 1000 m. We analyzed the number of road kills of red fox and European badger separately in a generalized linear model, whereas explanatory variables we used land cover types (based on the Corine Land Cover inventory) and traffic volume. Mean annual mortality from road collisions amounts to 2.36% of the red fox population and 3.82% of the European badger population. We found that the buffer size determines the results of the impact of land cover on mesocarnivore mortality on roads. The red fox differed from the European badger in response to land cover depending on the buffer size. The differences we have shown relate in particular to built-up areas. Our results indicate a 500-m buffer as best reflecting the land cover effects in road kills of both species. This was confirmed by model evaluation and a tendency to use or avoid the vicinity of human settlements of the analyzed species. We concluded that buffer size will probably affect mostly the significance of cover types that are spatially correlated with roads, positively or negatively. We suggest that the home range size of given species in local conditions should be assessed before determining the size of the buffer for analysis.

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Tree-Ring Growth of Larch (Larix decidua Mill.) in the Polish Sudetes—The Influence of Altitude and Site-Related Factors on the Climate–Growth Relationship

Forests ◽

10.3390/f9110663 ◽

2018 ◽

Vol 9 (11) ◽

pp. 663 ◽

Cited By ~ 2

Author(s):

Małgorzata Danek ◽

Monika Chuchro ◽

Adam Walanus

Keyword(s):

Tree Ring ◽

Climatic Factors ◽

Negative Relationship ◽

Thermal Conditions ◽

Cambial Activity ◽

Negative Influence ◽

Larix Decidua ◽

Related Factors ◽

Local Conditions ◽

Negative Effect

In this paper, the first study of a regional character on the influence of climatic factors on the tree-ring growth of European larch (Larix decidua Mill.) growing in the Polish Sudetes is presented. The obtained results indicate the relatively high diversity of the climatic signal observed in the tree rings of larches growing in the Sudetes. The most significant differentiating factor is altitude. The results suggest that the possible influence of local conditions (e.g., summit proximity, soil and bedrock characteristics, and exposure to strong winds) could also be of importance. A positive relationship between tree-ring growth and May temperatures was noted throughout the area; this indicates the principal importance of thermal conditions during the initial stage of cambial activity and tree-ring formation in larches from the Sudetes. The negative effect of the temperatures in the previous summer upon the tree-ring growth of larch in the subsequent year was also observed. The studies also indicate the negative influence of the water stress in summer (particularly in July of the previous year) upon the growth of trees. The negative relationship between tree-ring growth and the previous November temperature could be explained by the need for a late-autumn cooling, which affects the development of assimilation apparatus in spring of the subsequent year, which indirectly affects the tree-ring growth in the same year.

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The new Swiss Glacier Inventory SGI2016: a detailed cartographic representation of Swiss glacier extent and supraglacial debris-cover

10.5194/egusphere-egu21-5873 ◽

2021 ◽

Author(s):

Andreas Linsbauer ◽

Matthias Huss ◽

Elias Hodel ◽

Andreas Bauder ◽

Mauro Fischer ◽

...

Keyword(s):

Surface Area ◽

Swiss Alps ◽

Aerial Images ◽

Aerial Photographs ◽

Slope Aspect ◽

Relative Area ◽

Glacier Surface ◽

Glacier Inventory ◽

Digital Elevation ◽

Debris Cover

With increasing anthropogenic greenhouse gas emissions and corresponding global warming, glaciers in Switzerland are shrinking rapidly as in many mountain ranges on Earth. Repeated glacier inventories are a key task to monitor such glacier changes and provide detailed information on the extent of glaciation, and important parameters such as area, elevation range, slope, aspect etc. for a given point or a period in time. Here we present the new Swiss Glacier Inventory (SGI2016) that has been acquired based on high-resolution aerial imagery and digital elevation models in cooperation with the Federal Office of Topography (swisstopo) and Glacier Monitoring in Switzerland (GLAMOS), bringing together topological and glaciological knowhow. We define the process, workflow and required glaciological adaptations to compile a highly accurate glacier inventory based on the digital Swiss topographic landscape model (swissTLM3D).The SGI2016 provides glacier outlines (areas), supraglacial debris cover, ice divides and location points of all glaciers in Switzerland referring to the years 2013-2018, whereas most of the glacier outlines have been mapped based on aerial images acquired between 2015-2017 (75% in number and 87% in area), with the centre year 2016. The SGI2016 maps 1400 individual glacier entities with a total glacier surface area of 961 km2 (whereof 11% / 104 km2 are debris-covered) and constitutes the so far most detailed cartographic representation of glacier extent in Switzerland. Analysing the dependencies between topographic parameters and debris-cover fraction on the basis of individual glaciers reveals that short glaciers with a moderate mean slope and glaciers with a low median elevation tend to have high debris fractions. A change assessment between the SGI1973 and SGI2016 based on individual glacier entities affirms the largest relative area changes for small glaciers and for low-elevation glaciers, whereas the largest glaciers show small relative area changes, though large absolute changes. The analysis further indicates a tendency for glaciers with a high share of supraglacial debris to show larger relative area changes.Despite of an observed strong glacier volume loss between 2010 and 2016, the total glacier surface area of the SGI2016 is somewhat larger than reported in the last Swiss glacier inventory SGI2010. Even though both inventories were created based on swisstopo aerial photographs, the additional data, tools, resources and methodologies used by the professional cartographers digitizing glacier outlines in 3D for the SGI2016, are able to explain the counter-intuitive difference between SGI2010 and SGI2016. A direct comparison of these two datasets is thus not meaningful, but an experiment where a representative glacier sample of the SGI2010 was re-assessed based on the approaches of the SGI2016 led to an upscaled total glacier surface area of 1010 km2 for the Swiss Alps around 2010. This indicates an area loss of 49 km2 between the two last Swiss glacier inventories. As swisstopo data products are and will be regularly updated, the SGI2016 is the first step towards a consistent and accurate data product of repeated glacier inventories in six-year time intervals that promises a high comparability for individual glaciers and glacier samples.

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A New Approach Using AHP to Generate Landslide Susceptibility Maps in the Chen-Yu-Lan Watershed, Taiwan

Sensors ◽

10.3390/s19030505 ◽

2019 ◽

Vol 19 (3) ◽

pp. 505 ◽

Cited By ~ 7

Author(s):

Thi Nguyen ◽

Cheng-Chien Liu

Keyword(s):

Landslide Susceptibility ◽

Binary Classification ◽

Correlation Coefficients ◽

Pairwise Comparison ◽

Drainage Density ◽

Slope Aspect ◽

Bivariate Analysis ◽

Susceptibility Map ◽

Related Factors ◽

New Approach

This paper proposes a new approach of using the analytic hierarchy process (AHP), in which the AHP was combined with bivariate analysis and correlation statistics to evaluate the importance of the pairwise comparison. Instead of summarizing expert experience statistics to establish a scale, we then analyze the correlation between the properties of the related factors with the actual landslide data in the study area. In addition, correlation and dependence statistics are also used to analyze correlation coefficients of preparatory factors. The product of this research is a landslide susceptibility map (LSM) generated by five factors (slope, aspect, drainage density, lithology, and land-use) and pre-event landslides (Typhoon Kalmaegi events), and then validated by post-event landslides and new landslides occurring in during the events (Typhoon Kalmaegi and Typhoon Morakot). Validating the results by the binary classification method showed that the model has reasonable accuracy, such as 81.22% accurate interpretation for post-event landslides (Typhoon Kalmaegi), and 70.71% exact predictions for new landslides occurring during Typhoon Kalmaegi.

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Rockfall Investigation and Hazard Assessment from Nang County to Jiacha County in Tibet

Applied Sciences ◽

10.3390/app10010247 ◽

2019 ◽

Vol 10 (1) ◽

pp. 247 ◽

Cited By ~ 2

Author(s):

Haiyang Liu ◽

Xueliang Wang ◽

Xiaohui Liao ◽

Juanjuan Sun ◽

Su Zhang

Keyword(s):

Rock Mass ◽

Hazard Assessment ◽

Cloud Model ◽

Rapid Development ◽

Slope Angle ◽

Project Planning ◽

Aerial Images ◽

Slope Aspect ◽

Human Engineering ◽

Rockfall Hazard

The influences of rockfall on human engineering have been increasing in Tibet with the rapid development of the western region of China. This study proposed a multi-approach to carry out rockfall investigation and hazard assessment. As a case study, the rockfall hazard from Nang County to Jiacha County in Tibet was assessed. Firstly, we summarized the characteristics of spatial distributions of typical rockfall sources using Digital Elevation Model (DEM) and unmanned aerial vehicle (UAV) aerial images with resolution of 10 m. According to the thresholds of slope angle, slope aspect and elevation distribution of typical rockfall sources, we obtained all of the rockfall source areas in study area semi-automatically in ArcGIS platform. Secondly, we improved the efficiency and accuracy of detailed field investigation by using a three-dimensional (3D) point cloud model and rock mass structure extraction software. According to the analysis result, the dominant joint set was J1, whose orientation was basically consistent with the Yarlung Tsangpo Fault. The combination of J1, J2 and J4 cut the rock mass into blocks of wedge with J1 as potential sliding planes. It was indicated that the stability of the rock mass in study area was mainly controlled by the characters of joint sets. Finally, we applied the improved reclassification criteria of the Rockfall Hazard Vector (RHV) method in rockfall hazard assessment according to protection capabilities of the current protection facilities, making the result more valuable for geohazards prevention work. Based on this multi-approach, we obtained that 10.92% of the 306 provincial highway and 9.38% of the power line were threatened by potential rockfall hazards in study area. The hazard assessment results of study area were also of certain guiding value to the linear project planning and geohazards prevention work.

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Images Time Series Analysis for Land Deformation and Mapping Shallow Landslides based on SENTINEL - 1 and Optical Satellite Images Data: Case Study on Batam Island, Indonesia

10.5194/egusphere-egu2020-5018 ◽

2020 ◽

Author(s):

Tiggi Choanji ◽

Michel Jaboyedoff ◽

Marc-Henri Derron ◽

Li Fei ◽

Chunwei Sun

Keyword(s):

Time Series ◽

Satellite Images ◽

Shallow Landslide ◽

Shallow Landslides ◽

Optical Images ◽

Interferometry Method ◽

Land Deformation ◽

Optical Satellite Images ◽

Immense Potential

As a growing city, Batam Islands has an immense potential to become one of the strategic positions in Southeast Asia. However, as the city developed, it also followed with the deformation and potential areas which has prone to shallow landslides. Using 32 Sentinel-1A Satellite Images Data and 17 years of Optical images data, analysis of time series is conducted using Persistent Scattered Interferometry method and mapped for landslide events in the Islands. As a result, several regions impacted 4 &#8211; 10 mm/year of velocity deformation in the center part of the island and several locations simulated to be prone to shallow landslide. So, by coupling method of SAR data and optical images, has giving prominent possibility for detecting and predicting hazard potential in this island.

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A Three-Month Follow-Up Study Evaluating Changes in Clinical Profile and Attitudes Towards Involuntary Admission

European Psychiatry ◽

10.1016/j.eurpsy.2016.01.1746 ◽

2016 ◽

Vol 33 (S1) ◽

pp. S477-S478 ◽

Cited By ~ 1

Author(s):

E. Bainbridge ◽

B. Hallahan ◽

D. McGuinness ◽

A. Higgins ◽

K. Murphy ◽

...

Keyword(s):

Psychiatric Inpatient ◽

Traumatic Experience ◽

Involuntary Admission ◽

Clinical Predictors ◽

Related Factors ◽

Explanatory Variables ◽

Positive Attitudes ◽

Competing Interest ◽

Over Time

IntroductionInvoluntary admission and treatment is often a traumatic experience for patients and there is a wide variation in attitudes towards care even when patients are recovered.Objectives/aimsThe purpose of this large prospective study was to identify clinical predictors of attitudes towards care during involuntary admission.MethodsThree hundred and ninety-one consecutively admitted involuntarily patients to three psychiatric inpatient units over a 30-month period were invited to participate in the study. Comprehensive assessments at admission and 3 months after discharge were attained including measures of symptoms, insight, functioning, attitudes towards involuntary admission and coercive experiences. Multiple linear regression modelling was used to determine the optimal explanatory variables for attitudes towards care.ResultsTwo hundred and sixty-three individuals participated at baseline and 156 (59%) successfully completed follow-up assessments. Individuals improved significantly over time clinically and in their attitudes towards their care. At baseline greater insight (P < 0.001) and less symptoms (P = 0.02) were associated with more positive attitudes towards care as was older age (P = 0.001). At follow-up, greater insight (P < 0.001), less symptoms (P = 0.02) and being older (P = 0.04) were associated with more positive attitudes towards care. More positive attitudes towards care at follow-up were associated with greater improvements in insight over time (P < 0.001) and having a diagnosis of an affective psychosis (P = 0.0009).ConclusionsThe best predictors of positive attitudes towards care during and after involuntary admission are illness related factors, such as levels of insight and improvement in insight, rather than service or legislation related factors, such as the use of coercive measures, seclusion and restraint.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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Evaluating underlying causative factors for earthquake-induced landslides and landslide susceptibility mapping in Upper Indrawati Watershed, Nepal

Geoenvironmental Disasters ◽

10.1186/s40677-021-00200-3 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Pawan Gautam ◽

Tetsuya Kubota ◽

Aril Aditian

Keyword(s):

Land Cover ◽

Landslide Susceptibility ◽

Total Curvature ◽

Susceptibility Mapping ◽

Landslide Susceptibility Mapping ◽

Slope Aspect ◽

Topographic Wetness Index ◽

Area Index ◽

Causal Factors ◽

Causative Factors

AbstractThe main objective of this study is to understand the overall impact of earthquake in upper Indrawati Watershed, located in the high mountainous region of Nepal. Hence, we have assessed the relationship between the co-seismic landslide and underlying causative factors as well as performed landslide susceptibility mapping (LSM) to identify the landslide susceptible zone in the study area. We assessed the landslides distribution in terms of density, number, and area within 85 classes of 13 causal factors including slope, aspect, elevation, formation, land cover, distance to road and river, soil type, total curvature, seismic intensity, topographic wetness index, distance to fault, and flow accumulation. The earthquake-induced landslide is clustered in Northern region of the study area, which is dominated by steep rocky slope, forested land, and low human density. Among the causal factors, 'slope' showed positive correlation for landslide occurrence. Increase in slope in the study area also escalates the landslide distribution, with highest density at 43%, landslide number at 4.34/km2, and landslide area abundance at 2.97% in a slope class (> 50°). We used logistic regression (LR) for LSM integrating with geographic information system. LR analysis depicts that land cover is the best predictor followed by slope and distance to fault with higher positive coefficient values. LSM was validated by assessing the correctly classified landslides under susceptibility categories using area under curve (AUC) and seed cell area index (SCAI). The LSM approach showed good accuracy with respective AUC values for success rate and prediction rate of 0.843 and 0.832. Similarly, the decreasing SCAI value from very low to very high susceptibility categories advise satisfactory accuracy of the LSM approach.

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Do an ecosystem engineer and environmental gradient act independently or in concert to shape juvenile plant communities? Tests with the leaf-cutter ant Atta laevigata in a Neotropical savanna

10.7287/peerj.preprints.1692v5 ◽

2018 ◽

Author(s):

Alan N Costa ◽

Emilio M Bruna ◽

Heraldo L Vasconcelos

Keyword(s):

Species Richness ◽

Plant Communities ◽

Environmental Conditions ◽

Ecosystem Engineer ◽

Dominant Role ◽

Canopy Cover ◽

Plant Establishment ◽

Related Factors ◽

Local Conditions ◽

Atta Laevigata

Background. Ecosystem Engineers are species that transform habitats in ways that influence other species. While the impacts of many engineers have been well described, our understanding of how their impact varies along environmental gradients remains limited. Although disentangling the effects of gradients and engineers on biodiversity is complicated – the gradients themselves can be altered by engineers – doing so is necessary to advance conceptual and mathematical models of ecosystem engineering. We used leaf-cutter ants (Atta spp.) to investigate the relative influence of gradients and environmental engineers on the abundance and species richness of woody plants. Methods. We conducted our research in South America's Cerrado. With a survey of plant recruits along a canopy cover gradient, and data on environmental conditions that influence plant recruitment, we fit statistical models that addressed the following questions: (1) Does A. laevigata modify the gradient in canopy cover found in our Cerrado site? (2) Do environmental conditions that influence woody plant establishment in the Cerrado vary with canopy cover or proximity to A. laevigata nests? (3) DoA. laevigata and canopy cover act independently or in concert to influence recruit abundance and species richness? Results. We found that environmental conditions previously shown to influence plant establishment in theCerradovaried in concert with canopy cover, but that ants are not modifying the cover gradient or cover over nests. However, ants are modifying other local environmental conditions, and the magnitude and spatial extent of these changes is consistent across the gradient. In contrast to prior studies, we found that ant-related factors (e.g., proximity to nests, ant changes in surface conditions), rather than canopy cover, had the strongest effect on the abundance of plant recruits. However, the diversity of plants was influenced by both the engineer and the canopy cover gradient. Discussion. Atta laevigata in the Cerrado modify local conditions in ways that have strong but spatially restricted consequences for plant communities. We hypothesize that ants indirectly reduce seedling establishment by clearing litter and reducing soil moisture, which leads to seed and seedling desiccation. Altering soil nutrients could also reduce juvenile growth and survivorship; if so these indirect negative effects of engineering could exacerbate their direct effects of harvesting plants. The effects ofAttaappear restricted to nest mounds, but they could be long-lasting because mounds persist long after a colony has died or migrated. Our results support the hypothesis that leaf-cutter ants play a dominant role in Cerrado plant demography. We suggest the ecological and economic footprint of these engineers may increase dramatically in coming decades due to the transformation of the Cerrado by human activities.

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