2,282 research outputs found

    Landslide and debris flow warning at regional scale. A real-time system using susceptibility mapping, radar rainfall and hydrometeorological thresholds

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    Rainfall triggered shallow slides and debris flows constitute a significant hazard that causes substantial economic losses and fatalities worldwide. Regional-scale risk mitigation for these processes is challenging. Therefore, landslide early warning systems (LEWS) are a helpful tool to depict the time and location of possible landslide events so that the hazardous situation can be managed more effectively. The main objective of this thesis is to set up a regional-scale LEWS that works in real-time over Catalonia (NE Spain). The developed warning system combines in real-time susceptibility information and rainfall observations to issue qualitative warnings over the region. Susceptibility has been derived combining slope angle and land use and land cover information with a simple fuzzy logic approach. The LEWS input rainfall information consists of high-resolution radar quantitative precipitation estimates (QPEs). To assess if a rainfall situation has the potential to trigger landslides, the LEWS applies a set of intensity duration thresholds. Finally, a warning matrix combines susceptibility and rainfall hazard to obtain a qualitative warning map that classifies the terrain into four warning classes. The evaluation of the LEWS performance has been challenging because of the lack of a systematic inventory, including the time and location of recent landslides events. Within the context of this thesis, a citizen-science initiative has been set up to gather landslide data from reports in social networks. However, some of the reports have significant spatial and temporal uncertainties. With the aim of finding the most suitable mapping unit for real-time warning purposes, the LEWS has been set-up to work using susceptibility maps based on grid-cells of different resolutions and subbasins. 30 m grid-cells have been chosen to compute the warnings as they offer a compromise between performance, interpretability of the results and computational costs. However, from an end users’ perspective visualising 30 m resolution warnings at a regional scale might be difficult. Therefore, subbasins have been proposed as a good option to summarise the warning outputs. A fuzzy verification method has been applied to evaluate the LEWS performance. Generally, the LEWS has been able to issue warnings in the areas where landslides were reported. The results of the fuzzy verification suggest that the LEWS effective resolution is around 1 km. The initial version of the LEWS has been improved by including soil moisture information in the characterisation of the rainfall situation. The outputs of this new approach have been compared with the outputs of LEWS using intensity-duration thresholds. With the new rainfall-soil moisture hydrometeorological thresholds, fewer false alarms were issued in high susceptibility areas where landslides had been observed. Therefore, hydrometeorological thresholds may be useful to improve the LEWS performance. This study provided a significant contribution to regional-scale landslide emergency management and risk mitigation in Catalonia. In addition, the modularity of the proposed LEWS makes it easy to apply in other regions.Els lliscaments superficials i els corrents d’arrossegalls sĂłn un fenomen perillĂłs que causa significants perdudes econĂČmiques i humanes arreu del mĂłn. La seva principal causa desencadenant Ă©s la pluja. La mitigaciĂł del risc degut a aquets processos a escala regional no es senzilla. Ena quest context, els sistemes d’alerta sĂłn una eina Ăștil per tal de predir el lloc i el moment en que es poden desencadenar possibles esllavissades en el futur, i poder fer una gestiĂł del risc mĂ©s eficient. L’objectiu principal d’aquesta tesi Ă©s el desenvolupament d’un sistema d’alerta per esllavissades a escala regional, que treballi en temps real a Catalunya. El Sistema d’alerta que s’ha desenvolupat combina informaciĂł sobre la susceptibilitat del terreny i estimacions de la pluja d’alta resoluciĂł per donar unes alertes qualitatives arreu del territori. La susceptibilitat s’ha obtingut a partir de la combinaciĂł d’informaciĂł del pendent del terreny, i els usos i les cobertes del sĂČl utilitzant un mĂštode de lĂČgica difusa. Les dades de pluja sĂłn observacions del radar meteorolĂČgic. Per tal d’analitzar si un determinat episodi de pluja te el potencial per desencadenar esllavissades, el sistema d’alerta utilitza un joc de llindars intensitat-durada. Posteriorment, una matriu d’alertes combina la susceptibilitat i la magnitud del episodi de pluja. El resultat, Ă©s un mapa d’alertes que classifica el terreny en quatre nivells d’alerta. Amb l’objectiu de definir quina unitat del terreny Ă©s la mĂ©s adient pel cĂ lcul de les alertes en temps real, el sistema d’alerta s’ha configurat per treballar utilitzant mapes de susceptibilitat basats en pĂ­xels de diverses resolucions, i en subconques. Finalment, l’opciĂł mĂ©s convenient Ă©s utilitzar pĂ­xels de 30 m, ja que ofereixen un compromĂ­s entre el funcionament, la facilitat d’interpretaciĂł dels resultats i el cost computacional. Tot i aixĂČ, la visualitzaciĂł de les alertes a escala regional emprant pĂ­xels de 30 m pot ser difĂ­cil. Per aixĂČ s’ha proposat utilitzar subconques per oferir un sumari de les alertes. Degut a la manca d’un inventari d’esllavissades sistemĂ tic, que contingui informaciĂł sobre el lloc i el moment en que les esllavissades es van desencadenar, l’avaluaciĂł del funcionament del sistema d’alerta ha sigut un repte. En el context d’aquesta tesi, s’ha creat una iniciativa per tal de recol·lectar dades d’esllavissades a partir de posts en xarxes socials. Malauradament, algunes d’aquestes dades estan afectades per incerteses espacials i temporals força importants. Per a l’avaluaciĂł el funcionament del sistema d’alerta, s’ha aplicat un mĂštode de verificaciĂł difusa. Generalment, els sistema d’alerta ha estat capaç de generar alertes a les zones on s’havien reportat esllavissades. Els resultats de la verificaciĂł difusa suggereixen que la resoluciĂł efectiva del sistema d’alerta etĂ  al voltant d’1 km. Finalment, la versiĂł inicial del sistema d’alerta s’ha millorat per tal poder incloure informaciĂł sobre l’estat d’humitat del terreny en la caracteritzaciĂł de la magnitud del episodi de pluja. Els resultats del sistema d’alerta utilitzant aquest nou enfoc s’han comparat amb els resultats que s’obtenen al cĂłrrer el sistema d’alerta utilitzant els llindars intensitat-durada. Mitjançant els nous llindars hidrometeorolĂČgics, el sistema emet menys falses alarmes als llocs on s’han desencadenat esllavissades. Per tant, utilitzar llindars hidrometeorolĂČgics podria ser Ăștil per millorar el funcionament del sistema d’alerta dissenyat. L’estudi dut a terme en aquesta tesi suposa una important contribuciĂł que pot ajudar en la gestiĂł de les emergĂšncies degudes a esllavissades a escala regional a Catalunya. A mĂ©s a mĂ©s, el fet de que el sistema sigui modular permet la seva fĂ cil aplicaciĂł en d’altres regions en un futur.Enginyeria del terren

    Controls on debris-flow avulsions: White Mountains of California and Nevada

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    The process by which debris flows shift from an active channel and branch out into new transport or depositional areas is termed “avulsion.” They pose serious risks for structures and populations on debris-flow fans, yet avulsion mechanisms are relatively unknown and unaccounted for in hazard assessments, as compared to avulsions of rivers and streams, which are better understood. This study analyzes six debris-flow fans in the White Mountains of California and Nevada to identify relationships between avulsion locations and channel characteristics, constrain the controlling factors on avulsion, assess the probability that avulsion will occur at specified locations, and develop a method to predict avulsion locations. A database of avulsion locations and their channel characteristics was compiled in the field. These were compared to the characteristics of other positions on the fan surface that show evidence of debris flows that did not avulse through stepwise, binary logistic regression. Results indicate that two-thirds of avulsion likelihood can be attributed to the percentage of boulders at the site, slope angle, channel width, and the ratio between flow thickness and average slope at the avulsion location. The accuracy of this model can be improved when it accounts for the presence of a coarse channel plug, which increases the likelihood of avulsion. Application of the model is demonstrated by runout simulations with forced avulsions from modeled channel plugs

    Dynamics and Modelling of the 2015 Calbuco eruption Volcanic Debris Flows (Chile). From field evidence to a primary lahar model

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    The Calbuco volcanic eruption of 2015, was characterized by two explosive phases with partialand major column collapses that triggered lahars in many of the flanks of the volcano. Large lahar flows descended to the southern flank where highly fractured ice bodies were emplaced on steep slopes.In this study, we present a chronology of the volcanic flows based on a multi parameterdata set that includes social media, reports of authoritative institutions, instrumental monitoringdata and published research literature on the eruption. Our review established thatlahars in the Amarillo river began during the first phase of the eruption due to the sustained emplacement of pyroclastic flows in its catchment. In contrast, we propose that the lahars in theBlanco – Correntoso river system and the Este river were likely to have been triggered by asudden mechanical collapse of the glacier that triggered mixed avalanches which transitionedinto lahars downstream.Our observations include inundation cross-sections, estimates of flow speeds, and characterization of the morphology, grain sizes, and componentry of deposits.Field measurements are used together with instrumental data for calibrating a dynamic, physics-based model of lahar, Laharflow. We model flows in the Blanco – Correntoso river system and explore the influence of the model parameters on flow predictions in an ensemble of simulations. We develop a calibration that accounts for the substantial epistemic uncertainties in our observations and the model formulation, that seeks to determine plausible ranges for the model parameters, including those representing the lahar source. Our approach highlights the parameters in the model that have a dominant effect on the ability of the model to match observations, indicating where further development and additional observations could improve model predictions. The simulations in our ensemble that provide plausible matches to the observations are combined to produce flow inundation maps

    Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5

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    This ïŹfth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different ïŹelds of applications and in mathematics, and is available in open-access. The collected contributions of this volume have either been published or presented after disseminating the fourth volume in 2015 in international conferences, seminars, workshops and journals, or they are new. The contributions of each part of this volume are chronologically ordered. First Part of this book presents some theoretical advances on DSmT, dealing mainly with modiïŹed Proportional ConïŹ‚ict Redistribution Rules (PCR) of combination with degree of intersection, coarsening techniques, interval calculus for PCR thanks to set inversion via interval analysis (SIVIA), rough set classiïŹers, canonical decomposition of dichotomous belief functions, fast PCR fusion, fast inter-criteria analysis with PCR, and improved PCR5 and PCR6 rules preserving the (quasi-)neutrality of (quasi-)vacuous belief assignment in the fusion of sources of evidence with their Matlab codes. Because more applications of DSmT have emerged in the past years since the apparition of the fourth book of DSmT in 2015, the second part of this volume is about selected applications of DSmT mainly in building change detection, object recognition, quality of data association in tracking, perception in robotics, risk assessment for torrent protection and multi-criteria decision-making, multi-modal image fusion, coarsening techniques, recommender system, levee characterization and assessment, human heading perception, trust assessment, robotics, biometrics, failure detection, GPS systems, inter-criteria analysis, group decision, human activity recognition, storm prediction, data association for autonomous vehicles, identiïŹcation of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classiïŹcation. Finally, the third part presents interesting contributions related to belief functions in general published or presented along the years since 2015. These contributions are related with decision-making under uncertainty, belief approximations, probability transformations, new distances between belief functions, non-classical multi-criteria decision-making problems with belief functions, generalization of Bayes theorem, image processing, data association, entropy and cross-entropy measures, fuzzy evidence numbers, negator of belief mass, human activity recognition, information fusion for breast cancer therapy, imbalanced data classiïŹcation, and hybrid techniques mixing deep learning with belief functions as well

    Assessing the widening age gap in British partisanship:The impact of values, maturation, and political mobilization

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    In Britain, age has traditionally been a strong predictor of vote choice, with older people much more likely to vote for the Conservatives and younger people much more likely to vote for Labour or the Liberal Democrats. Remarkably, this age gap has increased consistently over the last three general elections and was also well reflected in the 2016 EU membership referendum, with younger voters much more likely to support Remain over Leave, leading scholars and polling agencies alike to note that age appears to have become the new distinctive cleavage in voting behaviour. This thesis contributes to the growing interest in this field of research by examining how age-related characteristics influence electoral choices from three different perspectives. The project comprises three research papers. Using over time British Election Study data, the first paper examines the link between age, education, and liberal-authoritarian and left-right values. The second paper considers the influence of life-cycle effects and tests the impact of the delayed transition into adulthood on Conservative voting. The third paper shifts the focus to the supply-side and using a specially designed survey experiment tests the impact of political appeals directed at younger cohorts on the age gap in party support

    New party entry and political engagement : electoral turnout and satisfaction with democracy

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    Defence date: 15 June 2023Examining Board: Prof. Hanspeter Kriesi, (European University Institute, supervisor); Prof. Elias Dinas, (European University Institute); Prof. Ruth Dassonneville, (University of MontrĂšal); Prof. Chris Anderson, (London School of Economics and Political Science)The last two decades have seen a surge in the institutionalization of new political parties, yet low levels of political engagement are persistent in many Western democracies. This raises questions about whether new parties can effectively channel political discontent and promote participation. This thesis argues that new party entry has distinct implications for different forms of political engagement. While new parties can increase electoral participation, they can also reinforce democratic dissatisfaction in affectively polarized environments. The empirical chapters provide evidence to support these arguments. Chapter 2 demonstrates that obtaining parliamentary representation does not significantly increase satisfaction with democracy and even reinforces political discontent among anti-establishment radical party voters. Chapter 3 introduces the concept of disruptive elections and shows that rapid electoral shifts can hinder changes in democratic satisfaction by introducing uncertainty into the government formation process. Chapter 4 proposes that considering an in-group/out-group logic is critical to understanding post-electoral changes in satisfaction with democracy among affectively polarized voters. It provides evidence that the establishment party win fosters political discontent among radical party voters despite electoral success. Finally, chapter 5 offers causal evidence that new party entry increases electoral turnout. These findings contribute to the growing literature on the effects of electoral change on political attitudes and behavior and highlight concerning implications for normative democratic theory. While new political parties may bring new forms of engagement, they can also exacerbate polarizing competition patterns that put democracy at risk. Ultimately, their impact depends on the specific conditions that led to their entry, urging us to consider ways to incorporate new political demands while reducing partisan animosity

    How did Britain come to this? A century of systemic failures of governance

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    If every system is perfectly designed to get the results it gets, what is wrong with the design of the systems that govern Britain? And how have they resulted in failures in housing, privatisation, outsourcing, education and healthcare? In How Did Britain Come to This? Gwyn Bevan examines a century of varieties of systemic failures in the British state. The book begins and ends by showing how systems of governance explain scandals in NHS hospitals, and the failures and successes of the UK and Germany in responding to Covid-19 before and after vaccines became available. The book compares geographical fault lines and inequalities in Britain with those that have developed in other European countries and argues that the causes of Britain’s entrenched inequalities are consequences of shifts in systems of governance over the past century. Clement Attlee’s postwar government aimed to remedy the failings of the prewar minimal state, while Margaret Thatcher’s governments in the 1980s in turn sought to remedy the failings of Attlee’s planned state by developing the marketised state, which morphed into the financialised state we see today. This analysis highlights the urgent need for a new political settlement of an enabling state that tackles current systemic weaknesses from market failures and over-centralisation. This book offers an accessible, analytic account of government failures of the past century, and is essential reading for anyone who wants to make an informed contribution to what an innovative, capable state might look like in a post-pandemic world

    China-US Competition

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    This open access edited book brings together a closer examination of European and Asian responses to the escalating rivalry between the US and China. As the new Cold War has surfaced as a perceivable reality in the post-COVID era, the topic itself is of great importance to policymakers, academic researchers, and the interested public. Furthermore, this manuscript makes a valuable contribution to an under-studied and increasingly important phenomenon in international relations: the impact of the growing strategic competition between the United States and China on third parties, such as small and middle powers in the two arguably most affected regions of the world: Europe and East Asia. The European side has been under-studied and explicitly comparative work on Europe and East Asia is extremely rare. Given that the manuscript focuses heavily on recent developments—and because many of these developments have been quite dramatic—there are very few publications that cover the same topics
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