Thesis (M.S.)--Oregon State University, 1997. / Typescript (photocopy). Includes bibliographical references (leaves 92-94). Also available on the World Wide Web.

This thesis examines the indirect impact of natural hazards on infrastructure networks. It addresses several key themes and issues for hazard assessment, network modelling and risk assessment using the case study of landslides impacting the national road network in Scotland, United Kingdom. The research follows four distinct stages. First, a landslide susceptibility model is developed using a database of landslide occurrences, spatial data sets and logistic regression. The model outputs indicate the terrain characteristics that are associated with increased landslide potential, including critical slope angles and south westerly aspects associated with increased rates of solar irradiance and precipitation. The results identify the hillslopes and road segments that are most prone to disruption by landslides and these indicate that 40 % (1,700 / 4,300 km) of Scotland s motorways and arterial roads (i.e. strategic road network) are susceptible to landslides and this is above previous assessments. Second, a novel user-equilibrium traffic model is developed using UK Census origin-destination tables. The traffic model calculates the additional travel time and cost (i.e. indirect impacts) caused by network disruptions due to landslide events. The model is applied to calculate the impact of historic scenarios and for sets of plausible landslide events generated using the landslide susceptibility model. Impact assessments for historic scenarios are 29 to 83 % greater than previous, including £1.2 million of indirect impacts over 15 days of disruption at the A83 Rest and Be Thankful landslide October 2007. The model results indicate that the average impact of landslides is £64 k per day of disruption, and up to £130 k per day on the most critical road segments in Scotland. In addition to identifying critical road segments with both high impact and high susceptibility to landslides, the study indicates that the impact of landslides is concentrated away from urban centres to the central and north-west regions of Scotland that are heavily reliant on road and haulage-based industries such as seasonal tourism, agriculture and craft distilling. The third research element is the development of landslide initiation thresholds using weather radar data. The thresholds classify the rainfall conditions that are most commonly associated with landslide occurrence in Scotland, improving knowledge of the physical initiation processes and their likelihood. The thresholds are developed using a novel optimal-point threshold selection technique, high resolution radar and new rain variables that provide spatio-temporally normalised thresholds. The thresholds highlight the role of the 12-day antecedent hydrological condition of soils as a precursory factor in controlling the rain conditions that trigger landslides. The new results also support the observation that landslides occur more frequently in the UK during the early autumn and winter seasons when sequences or clustering of multiple cyclonic-storm systems is common in periods lasting 5 to 15 days. Fourth, the three previous elements are combined to evaluate the landslide hazard of the strategic road segments and a prototype risk assessment model is produced - a catastrophe model. The catastrophe model calculates the annual average loss and aggregated exceedance probability of losses due to the indirect impact of landslides in Scotland. Beyond application to cost-benefit analyses for landslide mitigation efforts, the catastrophe model framework is applicable to the study of other natural hazards (e.g. flooding), combinations of hazards, and other infrastructure networks.

The prediction of motion of slowly moving landslides, also referred to as creeping slopes, is important for the reduction of landslide hazards. Such continuous and slowly moving landslides do not represent the usual stability problems of geotechnical analysis because these slopes are neither still nor ruptured but they move. For proper modeling of the motion of landslides, it is essential to develop improved techniques that integrate appropriate modeling of geological materials involved, laboratory and field tests, and verifications using computational methods. This dissertation focusses attention on the development of such an appropriate model for the time-dependent behavior of creeping landslides. Based on field observations it is proposed that the phenomenon of creeping landslides can be considered as involving the motion of a large mass of soil over a parent (fixed) mass with pronounced shear deformations occuring in a thin layer between the moving mass and the parent mass. The thin layer is refered to as interface zone while the overlying mass is refered to as solid body. The generalized Hierarchical Single Surface (HiSS) series of plasticity models are adopted to characterize the solid body. The interface zone is modeled using the specialization of the HiSS models for conditions occuring in the thin layer. Time dependency is introduced in constitutive models by adopting Perzyna's elastoviscoplastic formulation. The parameters for the HiSS and interface models are determined from laboratory tests on soils obtained from an actual slowly moving landslide at Villarbeney in Switzerland. Triaxial tests along various stress paths and oedemeter tests are conducted for the solid body. New analytical solutions are derived for prediction of oedometer tests. A general procedure for determination of viscous parameters is developed and techniques to process raw creep test data are proposed. Novel and representative simple shear interface tests are conducted to find parameters for the interface model. Special techniques for experimental analysis have been developed. A modified interface model to simulate the observed phenomenon of only compaction under shear is proposed. The parameters for the constitutive models are verified by numerically backpredicting experimental tests. An existing finite element code has been modified to incorporate various aspects of the small strain elastoviscoplastic formulation. Field measurements in the form of inclinometer profiles at various borehole locations on Villarbeney landslide are available. These inclinometer profiles are predicted using the proposed model. A comparison of the field measurements and the results from finite element analysis shows that such a model can be successfully used for predicting the behavior of slowly moving landslides.

In geotechnical engineering, granular flows are often studied as a means to further the understanding of the mechanisms that drive landslide motion. High quality experimental data is essential in providing evidence for the development and verification of new theoretical methods that link complex grain interactions to the extended mobility of some landslide events. At present, limited experimental data is available that captures the full range of landslide mobility. In an attempt to add to the present data sources, high quality experimental data was obtained through the use of high speed cameras and physical modelling using a geotechnical centrifuge and a large scale landslide flume. These modelling techniques allow for landslide motion, representative of field scale events, to be observed in a well-defined and controlled setting. A series of nine tests were performed in a geotechnical centrifuge under varying slope inclinations and Coriolis conditions. The effects of Coriolis on landslide mobility were evident when comparing final deposit shapes and total runout. The effects of Coriolis were more pronounced for higher velocity situations and when material was travelling on the horizontal base section opposed to the sloped section of the physical model. A series of thirty tests were performed using a large scale flume under varying source volumes and basal friction conditions, capturing the grain scale interactions and overall runout behaviour. The grain interactions and ultimately the flow behavioural regimes developed were a function of material source volume and boundary roughness. The dimensionless inertial number was used to classify flows into behavioural regimes, but was found to break down when describing transitions to the granular gas behavioural regime. The runout-time results and final deposit shapes showed significant variation between test configurations, indicating the effects of volume and basal friction on overall mobility. Using the depth averaged numerical model, DAN, it was found that a single set of empirically derived frictional parameters (i.e. specific to internal and basal friction conditions) was appropriate for matching the overall mobility of the experimental flows over a range of flow volumes and slope inclinations. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-09-25 15:48:54.761

A compreensão dos condicionantes deflagradores de movimentos de massa é importante na medida em que a partir do entendimento desses é possível prevenir ou mitigar desastres naturais em determinada região. No caso do município de Baixo Guandu-ES, mais de 1200 cicatrizes de deslizamentos foram fotointerpretadas e posteriormente checadas em trabalhos de campo. Segundo informações da Defesa Civil Municipal a deflagração desses eventos se deu, majoritariamente, em 25 de dezembro de 2013 durante uma forte precipitação, causada por um corredor de umidade que estacionou sobre a região pela ação de uma Zona de Convergência do Atlântico Sul. Cerca de 77% das cicatrizes mapeadas estão em encostas com declividade não superiores a 30º. Até o dia 23 de dezembro, apesar do acumulado de chuva de mais de 600 milímetros, nenhum ou pouco evento de movimentações de massa haviam ocorrido no município. As análises mostraram que a região com maior quantidade de cicatrizes observada é coincidente com a área onde o acumulado de chuva entre os dias 23/12/2013 e 24/12/2013 (dois dias antes de ocorrer os deslizamentos) foi de mais de 120 milímetros. Dentre as condicionantes estudadas, o principal agente deflagrador para os movimentos de massa que atingiram região de Baixo Guandu-ES foi a chuva de dois dias antes dos eventos, onde o solo já se encontrava quase saturado e as forças atuantes estavam praticamente iguais as forças de resistentes do maciço. / The knowledge of the triggering factors of mass movements is important for the prevention and mitigation of natural disasters in a particular region. In the case of the municipality of Baixo Guandu-ES, more than 1200 sliding scars were photointerpreted and later assessed in field work. According to information shared by the Municipal Civil Defense Office, the outbreak of these events had occurred mainly on December 25, 2013 during a heavy rainfall, caused by a humidity corridor that parked over the region by the action of a South Atlantic Convergence Zone. About 77% of the scars mapped are located on slopes not exceeding 30º. Until December 23, despite accumulated rain of more than 600 millimeters, no mass movement event had occurred in the city. Data revealed that the region with the highest number of scars coincides with the area where the accumulated rainfall between 12/23/2013 and 12/24/2013 (two days before landslides) was more than 120 mm. Among the potential variables studied, the main deflagrating agent for the mass movements that reached the Baixo Guandu-ES region was the rainfall of two days before the events; since the soil was already almost saturated and the driving forces were practically equal to the resistance forces.

Masters Research - Master of Science / Recent flash floods and landslides in the Philippines have caused many fatalities, loss of livelihoods; destroyed infrastructures, damaged natural resources and displaced several communities. Investigation of five disaster cases of flash floods and landslides from 1991 to 2006 was undertaken to gain an understanding of the causes, behaviour, distribution and biophysical impacts of these recurrent natural hazards. Sustaining healthy and resilient communities and protecting the ecosystem from natural disasters is a key development goal. Therefore, communities at risk need to adequately prepare for, respond to, and recover from the impacts of these natural disasters. A theory model on community resilience called the Landslip-Disaster Quadrant Model was developed to examine the capacity for resilience and the vulnerability of threatened communities. Six building blocks comprise this Model. A community study of the February 17, 2006 landslides in St. Bernard, Southern Leyte, was conducted to test and refine this Model. Major findings of the study have revealed that flash floods and landslides have been frequent due to changing climatic patterns and greater interaction of natural processes. Extreme weather conditions have resulted in intense rainfall that seeps through fractures and cracks in the ground. Rains saturate and loosen soil particles, weaken slope resistance, triggering landslides that formed natural dams. Failure of these natural dams or log jams caused flash floods and debris flows. The rapidity and destructiveness of these hazards were influenced by the angular position of sliding materials, slope resistance, type of cascading materials caught in the flow, river channel configuration, and human structures that obstruct and/or intensify overflow. These were the physical conditions of vulnerability to disasters in the five cases of natural disaster investigated. Rural livelihoods and the economic base of the local people in Saint Bernard, Southern Leyte, were limited and subsistent. Though the local people have a high literacy rate, they have inadequate understanding of the natural processes associated with landslides. Natural observations such as receding water levels in the river, fractures and cracks in the ground on the mountain, excessive rains and landslides in nearby communities could have been used as early warnings by the local people and authorities for safe evacuation. Many lives in Guinsaugon village could have thus been saved from the deadly landslides of 17 February 2006. Political interests have affected progress of resettlement housing and development projects that obliged many local people to extend the period spent living in the evacuation centres. However, the local people were expressive of their faith and hope to rise from the tragedy. These ‘bouncing back’ attitudes of the local people were indicative of their strong cultural values that formed the core of their coping capacity for natural disasters. The results of the community study tested and refined the Landslip-Disaster Quadrant Model. Among the six blocks for building a disaster-resilient community, cultural values and local norms ranked first. This is followed by ecological security, then livelihood sufficiency and economic base, and further by human health and wellness. The last two blocks were structural networks and institutional arrangements, and political will and priorities. This Model could form the framework for a Comprehensive Landslide and Flash Flood Disaster Risk Assessment in the Philippines. The community assessment toolkit developed in this study could be expanded further into policy and planning guidelines of the National Disaster Coordinating Council of the Philippines.

<p><p>All around the world the global climate change has become an important issue and its impact has been widely discussed. In the Everest region the environment is extra sensitive to changes due to the numbers of glaciers in the area. When glaciers are melting and ground temperature is rising it is likely to affect the area by causing more hazards. The area also has an extreme relief and high seismic activity, which also contribute to the numerous hazards. An increasing number of hazards could be a danger both to local people and to tourists visiting the area. Local people are forced to build houses in high risk areas due to limited supply of land suitable for farming and living in the mountains.</p><p>We made a field trip to Khumbu valley, in the Everest region. On the field trip we mapped the location of hazards and examined where there was a risk of future hazards to occur. The hazards were surveyed with GPS. Maps and analyses were generated with GIS software at the Himalayan environmental research center in Kathmandu, ICIMOD. We digitalized the hazards and hyperlinked photos to them. We also did an image difference analysis, where we compared satellite images from different years to see whether the number of hazards had increased. The result indicated that from 1976 to 2000 the number of hazards have increased, especially along the river. The photo documentation provides a basis for follow-up studies of the future development of the hazardous areas.</p><p>A number of diagrams were made to visualize results from the field trip. It can be seen that there are many hazards close to where people are living and close to trails. We also compared our digitalized hazards to risk maps (from 1985 and 2005) to see which risk zone our hazards belonged to. A slope map of the area was created with hyperlinked photos from the sites.</p></p> / <p><p>Frågan om hur klimatförändringar kommer att påverka vår miljö har blivit ett stort samtalsämne i hela världen. Everestområdet i Nepal är extra känsligt för förändringar på grund av att det finns många glaciärer i området. När glaciärerna smälter och marktemperaturen stiger kommer det troligtvis att påverka antalet skred i området.</p><p>En ökning av antalet skred kan medföra större risker för lokalbefolkning och turister, som vistas i området. Det är därför viktigt att informera och utbilda lokalbefolkningen om var det är säkert att bygga nya hus m.m.</p><p>Vi har gjort ett fältarbete i Khumbudalen som ligger i Everestområdet. Under fältvistelsen kartlade och fotograferade vi skredens utbredning och undersökte var risken för skred är som störst. Skreden och sluttningarna mättes in med hjälp av GPS. Efter fältvistelsen gjorde vi kartor och analyser med hjälp av GIS, på ett forskningscentrum i Kathmandu, ICIMOD. Vi digitaliserade skred och länkade foton till dem. Vi gjorde också en förändringsanalys där vi jämförde satellitbilder från olika år (1976 till 2000) för att se om förekomsten av skred har ökat.</p><p>Resultatet visar en ökning av antalet skred särskilt utmed floden. Fotodokumentationen utgör en grund för uppföljningsstudier av utvecklingen av skred i området.</p><p>Ett antal diagram skapades för att visa resultaten från fältvistelsen. Det framgår att det finns många skred där människor lever och vid vandringsstigar. Vi jämförde också våra digitaliserade skred med riskkartor från 1985 och 2005 för att se i vilken riskzon skreden ligger i.</p><p>En sluttningskarta över området skapades med foton länkade till kartan.</p></p>

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 143-158).

All around the world the global climate change has become an important issue and its impact has been widely discussed. In the Everest region the environment is extra sensitive to changes due to the numbers of glaciers in the area. When glaciers are melting and ground temperature is rising it is likely to affect the area by causing more hazards. The area also has an extreme relief and high seismic activity, which also contribute to the numerous hazards. An increasing number of hazards could be a danger both to local people and to tourists visiting the area. Local people are forced to build houses in high risk areas due to limited supply of land suitable for farming and living in the mountains. We made a field trip to Khumbu valley, in the Everest region. On the field trip we mapped the location of hazards and examined where there was a risk of future hazards to occur. The hazards were surveyed with GPS. Maps and analyses were generated with GIS software at the Himalayan environmental research center in Kathmandu, ICIMOD. We digitalized the hazards and hyperlinked photos to them. We also did an image difference analysis, where we compared satellite images from different years to see whether the number of hazards had increased. The result indicated that from 1976 to 2000 the number of hazards have increased, especially along the river. The photo documentation provides a basis for follow-up studies of the future development of the hazardous areas. A number of diagrams were made to visualize results from the field trip. It can be seen that there are many hazards close to where people are living and close to trails. We also compared our digitalized hazards to risk maps (from 1985 and 2005) to see which risk zone our hazards belonged to. A slope map of the area was created with hyperlinked photos from the sites. / Frågan om hur klimatförändringar kommer att påverka vår miljö har blivit ett stort samtalsämne i hela världen. Everestområdet i Nepal är extra känsligt för förändringar på grund av att det finns många glaciärer i området. När glaciärerna smälter och marktemperaturen stiger kommer det troligtvis att påverka antalet skred i området. En ökning av antalet skred kan medföra större risker för lokalbefolkning och turister, som vistas i området. Det är därför viktigt att informera och utbilda lokalbefolkningen om var det är säkert att bygga nya hus m.m. Vi har gjort ett fältarbete i Khumbudalen som ligger i Everestområdet. Under fältvistelsen kartlade och fotograferade vi skredens utbredning och undersökte var risken för skred är som störst. Skreden och sluttningarna mättes in med hjälp av GPS. Efter fältvistelsen gjorde vi kartor och analyser med hjälp av GIS, på ett forskningscentrum i Kathmandu, ICIMOD. Vi digitaliserade skred och länkade foton till dem. Vi gjorde också en förändringsanalys där vi jämförde satellitbilder från olika år (1976 till 2000) för att se om förekomsten av skred har ökat. Resultatet visar en ökning av antalet skred särskilt utmed floden. Fotodokumentationen utgör en grund för uppföljningsstudier av utvecklingen av skred i området. Ett antal diagram skapades för att visa resultaten från fältvistelsen. Det framgår att det finns många skred där människor lever och vid vandringsstigar. Vi jämförde också våra digitaliserade skred med riskkartor från 1985 och 2005 för att se i vilken riskzon skreden ligger i. En sluttningskarta över området skapades med foton länkade till kartan.

Empirically-based models of landslide distribution and susceptibility are currently the most commonly used approach for mapping probabilities of landslide initiation and analyzing their association with natural and anthropogenic environmental factors. In general, these models statistically estimate susceptibility based on the predisposition of an area to experience a landslide given a range of environmental factors, which may include land use, topography, hydrology and other spatial attributes. Novel statistical approaches include the generalized additive model (GAM), a non-parametric regression technique, which is used in this study to explore the relationship of landslide initiation to topography, rainfall and forest land cover and logging roads on Vancouver Island, British Columbia. The analysis is centered on an inventory of 639 landslides of winter 2006/07. Data sources representing potentially relevant environmental conditions of landslide initiation are based on: terrain analysis derived from a 20-m CDED digital elevation model; forest land cover classified from Landsat TM scenes for the summer before the 2006 rainy season; geostatistically interpolated antecedent rainfall patterns representing different temporal scales of rainfall (a major storm, winter and annual rainfall); and the main lithological units of surface geology. In order to assess the incremental effect of these data sources to predict landslide susceptibility, predictive performances of models based on GAMs are compared using spatial cross-validation estimates of the area under the ROC curve (AUROC), and variable selection frequencies are used to determine the prevalence of non-parametric associations to landslides. In addition to topographic variables, forest land cover (e.g., deforestation), and logging roads showed a strong association with landslide initiation, followed by rainfall patterns and the very general lithological classification as less important controls of landscape-scale landslide activity in this area. Annual rainfall patterns are found not to contribute significantly to model prediction improvement and may lead to model overfitting. Comparisons to generalized linear models (i.e., logistic regression) indicate that GAMs are significantly better for modeling landslide susceptibility. Overall, based on the model predictions, the most susceptible 4% of the study area had 29 times higher density of landslide initiation points than the least susceptible 73% of the study area (0.156 versus 0.005 landslides/km2).