Framework Convention on Climate Change

Social Vulnerability to Environmental Hazards

[1] Various methods have been proposed in the literature to predict the rainfall conditions that are likely to trigger landslides in a given area. Most of these methods, however, only consider the rainfall events that resulted in landslides and provide deterministic thresholds with a single possible output (landslide or no-landslide) for a given input (rainfall conditions). Such a deterministic view is not always suited to landslides. Slope stability, in fact, is not ruled by rainfall alone and failure conditions are commonly achieved with a combination of numerous relevant factors. When different outputs (landslide or no-landslide) can be obtained for the same input a probabilistic approach is preferable. In this work we propose a new method for evaluating rainfall thresholds based on Bayesian probability. The method is simple, statistically rigorous, and returns a value of landslide probability (from 0 to 1) for each combination of the selected rainfall variables. The proposed approach was applied to the Emilia-Romagna Region of Italy taking advantage of the historical landslide archive, which includes more than 4000 events for which the date of occurrence is known with daily accuracy. The results show that landsliding in the study area is strongly related to rainfall event parameters (duration, intensity, total rainfall) while antecedent rainfall seems to be less important. The distribution of landslide probability in the rainfall duration-intensity shows an abrupt increase at certain duration-intensity values which indicates a radical change of state of the system and suggests the existence of a real physical threshold.

Probabilistic rainfall thresholds for landslide occurrence using a Bayesian approach

Flow-like landslides, such as debris flows and rock avalanches, travel at extremely rapid velocities and can impact large areas far from their source. When hazards like these are identified, runout analyses are often needed to delineate potential inundation areas, estimate risks, and design mitigation structures. A variety of tools and methods have been developed for these purposes, ranging from simple empirical–statistical correlations to advanced three-dimensional computer models. This paper provides an overview of the tools and methods that are currently available and discusses some of the main challenges that are currently being addressed by researchers, including the need for better guidance in the selection of model input parameter values, the challenge of translating model results into vulnerability estimates, the problem with too much initial spreading in the simulation of certain types of landslides, the challenge of accounting for sudden channel obstructions in the simulation of debris flows, an...

2014 Canadian Geotechnical Colloquium: Landslide runout analysis — current practice and challenges

Matrices, curves and indicators: A review of approaches to assess physical vulnerability to debris flows

https://homepage.univie.ac.at/thomas.glade/Publications/EidsvigEtAl2014.pdf

Quantification of model uncertainty in debris flow vulnerability assessment

The severity of the impact of a natural hazard on a society depends on, among other factors, the intensity of the hazard and the exposure and resistance ability of the elements at risk (e.g., persons, buildings and infrastructures). Social conditions strongly influence the vulnerability factors for both direct and indirect impact and therefore control the possibility to transform the occurrence of a natural hazard into a natural disaster. This article presents a model to assess the relative socioeconomic vulnerability to landslides at the local to regional scale. The model applies an indicator-based approach. The indicators represent the underlying factors that influence a community’s ability to prepare for, deal with, and recover from the damage and loss associated with landslides. The proposed model includes indicators that characterize the demographic, social and economic setting as well as indicators representing the degree of preparedness, effectiveness of the response and capacity to recover. Although this model focuses primarily on the indirect losses, it could easily be extended to include physical indicators accounting for the direct losses. Each indicator is individually ranked from 1 (lowest vulnerability) to 5 (highest vulnerability) and weighted, based on its overall degree of influence. The final vulnerability estimate is formulated as a weighted average of the individual indicator scores. The proposed model is applied for six case studies in Europe. The case studies demonstrate that the method gives a reasonable ranking of the vulnerability. The practical experience achieved through the case studies shows that the model is straightforward for users with knowledge on landslide locations and with access to local census data.

Assessment of socioeconomic vulnerability to landslides using an indicator-based approach: methodology and case studies

Reliability of API, NGI, ICP and Fugro Axial Pile Capacity Calculation Methods

. In recent years, flow-like landslides have extensively affected pyroclastic
covers in the Campania region in
southern Italy, causing human suffering and conspicuous economic damages. Due to the high
criticality of the area, a proper assessment of future variations in event
occurrences due to expected climate changes is crucial. The study assesses
the temporal variation in flow-like landslide hazard for a section of the A3
“Salerno–Napoli” motorway, which runs across the toe of the Monte Albino
relief in the Nocera Inferiore municipality. Hazard is estimated spatially
depending on (1) the likelihood of rainfall-induced event occurrence within
the study area and (2) the probability that the any specific location in the
study area will be affected during the runout. The probability of
occurrence of an
event is calculated through the application of Bayesian theory. Temporal
variations due to climate change are estimated up to the year 2100
through an ensemble of high-resolution climate projections, accounting for
current uncertainties in the characterization of variations in rainfall
patterns. Reach probability, or defining the probability that a given spatial
location is affected by flow-like landslides, is calculated spatially based
on a distributed empirical model. The outputs of the study predict substantial
increases in occurrence probability over time for two different scenarios of
future socioeconomic growth and
atmospheric concentration of greenhouse gases.

https://nhess.copernicus.org/articles/18/3019/2018/nhess-18-3019-2018.pdf

Temporal evolution of flow-like landslide hazard for a road infrastructure in the municipality of Nocera Inferiore (southern Italy) under the effect of climate change

Increasingly, society and standards require "risk-informed" decisions. The paper demonstrates the benefits of implementing reliability and risk concepts in dam engineering as a complement to conventional deterministic analyses. Reliability evaluations can range from qualitative estimates, to simple statistical evaluations, to full probabilistic modelling of the hazards and consequences for a system of dams. The paper gives an overview of basic concepts of reliability-based approaches and illustrates their use with three case studies. The paper discusses the strengths of reliability-based analyses and key issues such as tolerable and acceptable risk, the meaning of factor of safety, the targets for a margin of safety and the selection of characteristic value for analysis. Reliability-based approaches provide useful insight and complementary information. They enable the analysis of complex uncertainties in a systematic and more complete manner than deterministic analyses alone, both for the design of dams and for their safety evaluation during their lifetime. Reliability and risk-based approaches assist with preparing engineering recommendations and making decisions. RÉSUMÉ: La société et les normes exigent de plus en plus de décisions "fondées sur le risque". L'article démontre les avantages de la mise en œuvre de concepts de fiabilité et du risque dans le dimensionnement de barrages comme un complément aux analyses déterministes classiques. Les évaluations de fiabilité peuvent être des estimations qualitatives, de simples évaluations statistiques, ou une modélisation probabiliste complète des aléas et des conséquences pour un système de barrages. L'article donne un aperçu des concepts de base des analyses fiabilistes et illustre leur utilisation avec des études de cas de trois barrages en remblai rocheux. Le document discute des points forts de l'approche fiabiliste et les questions clés telles que le risque tolérable et acceptable, la signification du facteur de sécurité, les objectifs pour une marge de sécurité et le choix de la valeur caractéristique pour l'analyse. L'article conclut que les approches basées sur la fiabilité fournissent des informations complémentaires utiles et permettent d'analyser des incertitudes complexes de manière systématique et plus complète que les analyses déterministes, tant pour la conception des barrages que pour leur évaluation pendant leur durée de vie. Des approches basées sur la fiabilité et le risque aideront à préparer les recommandations d'ingénierie et à prendre de bonnes décisions.

Unni Eidsvig

Papers

Quantification of model uncertainty in debris flow vulnerability assessment

Assessment of socioeconomic vulnerability to landslides using an indicator-based approach: methodology and case studies

Reliability of API, NGI, ICP and Fugro Axial Pile Capacity Calculation Methods

Temporal evolution of flow-like landslide hazard for a road infrastructure in the municipality of Nocera Inferiore (southern Italy) under the effect of climate change

Risk assessment and dams – Recent developments and applications