This study investigates the February 17th, 2006 massive rockslide that occurred in the island of Leyte, Philippines following heavy rainfall and four minor earthquakes. The rockslide is considered one of the largest and most catastrophic slides in the last few decades as it completely inundated the village of Guinsaugon, taking the lives of approximately 1,400 of the 1,800 residents of the village. The distinct element simulation of the rockslide is performed using 3DEC (Three-Dimensional Distinct Element Code) in order to investigate the underlying triggering mechanism of the slide as well as the behavior of the debris flow. The 3DEC models were established based on field observations from the U.S. Reconnaissance team and material and joint properties based on in-situ and laboratory test results. The possible triggering mechanisms considered in the distinct element analyses were the rainfall-induced hydraulic pressurization of the fault forming part of the main scarp, as well as the seismic acceleration due to the minor earthquakes that occurred the morning of the slide. The results of the analyses and simulations indicate that the rainfall-induced hydraulic pressurization of the fault was potentially the main trigger for the initiation of the slide. The minor earthquakes, which occurred before and around the time of the slide initiation, appeared to have very little effect on the triggering mechanism and the debris flow are comparable to witness accounts and field observations. The results presented in this study are expected to provide better understanding of rockslides such as the one that occurred in the Philippines on February 17, 2006. With further improvements in computational capabilities in the future, distinct element simulations can have the potential to reliably predict the initiation and behavior of slides, and help mitigate their impact. / Master of Science

This thesis presents the computer model FORWP that is capable of predicting attenuation and cross polarization at 10-30 GHz from dual-polarization radar data with a high degree of accuracy. FORWP uses a rigorous backscattering computer model BSCAT to infer rain drop size distribution along the slant path from radar measured reflectivity and differential reflectivity data collected along the path. Then, two semi-empirical models are developed which predict attenuation from radar measured reflectivity and differential reflectivity. These two semi-empirical models are used to evaluate FORWP. Finally, attenuation predictions of FORWP are compared to the two semi-empirical prediction models and measured link attenuation at 11.4 GHz for a rain event in southwest Virginia. / M.S.

The suitability of using rain-flow reconstructions as an alternative to an original loading spectrum for component fatigue life testing is investigated. A modified helicopter maneuver history is used for the rain-flow cycle counting and history regenerations. Experimental testing on a notched test specimen over a wide range of loads produces similar lives for the original history and the reconstructions. The test lives also agree with a simplified local strain analysis performed on the specimen utilizing the rain-flow cycle count. The rain-flow reconstruction technique is shown to be a viable test spectrum alternative to storing the complete original load history, especially in saving computer storage space and processing time. A description of the regeneration method, the simplified life prediction analysis, and the experimental methods are included in the investigation. / Master of Science

No description available.

A frequente ocorrência de desastres naturais gera impactos sociais e econômicos cada vez maiores, impondo a necessidade de elaborar estratégias de prevenção e redução de riscos. No cenário nacional, os desastres causados por eventos hidrológicos representam a maior parte das ocorrências. Acidentes de maior exposição e maiores consequências são os ocasionados por movimentos gravitacionais de massa. Assim, as iniciativas de prevenção de desastres necessariamente passam pelo detalhamento do conhecimento do problema, o que deve orientar o estabelecimento de metas de ações de redução de risco, instrumentos de gestão e resposta, e ainda para sistemas de monitoramento e alerta. Estes sistemas necessariamente devem contar com mapeamentos dos locais de risco, rede de coleta de dados meteorológicos que subsidiem previsões de eventos hidrológicos, e o estabelecimento dos limiares críticos de chuva deflagradores de escorregamentos. Com tais objetivos, órgãos governamentais promoveram esforços no mapeamento dos riscos, em escalas adequadas, e o investimento na estruturação de redes de monitoramento hidrometeorológico, sendo necessárias iniciativas de elaboração de limiares críticos regionalizados a serem amplamente desenvolvidas. Dentro do cenário da gestão de riscos descritos, este trabalho teve como principal objetivo a determinação de limiares críticos de chuva deflagradores de movimentos gravitacionais de massa no município de São Bernardo do Campo. Baseando-se na avaliação dos dados de série histórica de pluviometria, e de um banco de dados formado a partir das ocorrências de escorregamentos atendidas no município, compreendendo 415 escorregamentos ao longo de 24 anos (1993 a 2016). Os resultados da correlação dos dados do meio físico, da pluviometria e das ocorrências de escorregamentos, permitiram uma série de análises da distribuição das ocorrências. A distribuição foi feita ao longo do tempo, em função de acumulados de chuva e em função dos aspectos do meio físico. Foram feitas também correlações da intensidade das chuvas em função da espacialização e acumulados de chuva. As correlações espaciais dos dados permitiram o estabelecimento de uma ferramenta que relaciona as caracterizações do meio físico com as ocorrências de escorregamentos, que foi denominado como Coeficiente de Ocorrências por Área (COPA). Este coeficiente indicou os elementos do meio físico de maior influência na deflagração de movimentos de massa na área de estudo, em ordem de prioridade os destaques foram: 1) muito alta densidade de ocupação; 2) padrões e morfologias de relevo de morros altos e morros baixos; 3) alta densidade de ocupação; 4) unidade geológica do Micaxisto; e 5) terrenos com inclinação superior a 25°. Destaca-se que o trabalho contribuiu para o conhecimento da resposta dos elementos de frente a processos hidrometeorológicos e para a definição de limiares críticos de chuva deflagradora de escorregamentos, determinando uma equação numérica de previsão de ocorrências a partir dos dados pluviométricos e de previsões meteorológicas. Estes resultados também puderam contribuir no estabelecimento de parâmetros técnico-científicos para refinar a gestão do risco de movimentos de massa em São Bernardo do Campo-SP, e das relações desses eventos com o meio físico para estabelecimento de estudos em outras localidades. / The frequent occurrence of landslides in Brazil has been the cause of larger issues, economically and socially, which explains the necessity to elaborate preventing strategies in order to reduce such risks to the population. Looking at the Brazilian panorama, the disasters caused by hydrological events represent the greater part of these occurrences. Mass gravitational movements cause accidents of a bigger exposure and have greater consequences. Thus, the prevention strategies must go through a detailed study, in order to gather knowledge to better understand the problem as a whole; this information must orientate the establishment of targets for risk reduction actions, management and response instruments, as well as the monitoring and alert systems. These systems must have risk mapping and meteorological data collection networks, in order to predict hydrological events and establish critical limits to landslides caused by rainfall. With these bjectives, government agencies have promoted efforts to map these areas in adequate scales, as well as investing and structuring hydrometereological monitoring networks, requiring initiatives to elaborate regionalized critical groundsels to be extensively developed. Within the scenario of risk management described, this study has the objective to determine critical thresholds triggered by rainfall of mass gravitational movements at the municipality of Sao Bernardo do Campo. Based on the evaluation of the historical data of rainfall, and database gathered from the occurrences of landslides that took place in the same municipality as well as, comprising 415 landslides that have happened for over 24 years (from 1993 to 2016). The correlated results in the physical environment data on occurrences of landslides caused by rainfall, started a series of analyzes on the distribution of these occurrences. This distribution was made throughout the described timeline, due to accumulated rain damage and other environmental aspects. Correlations on the rainfall intensity were also made due to the spacing of the damaged land. This spacing correlated data allowed the establishment of a tool that relates the characterizations of the environment with the gathered data on landslides, which was named as the Coefficient of Occurrences per Area (COPA). This coefficient indicates the physical environment elements, and had the greatest influence on the deflagration of mass movements at the studied area. In priority order, the emphasized topics were: 1) very high density of land occupation; 2) landforms high hills and low hills; 3) high density of land occupation; 4) geological unity of Mica Schist; and 5) terrains with an inclination higher than 25°. This study contributes to the knowledge on how the physical environment elements reacts ahead of hydrometeorological processes and to the definition of critical limits of rainfall that triggers landslides. Also, it has determined a numerical equation to landslides prediction from rainfall data and meteorological forecast. All these results could also contribute to the establishment of technical-scientific parameters, refining mass movement risk management at the city of São Bernardo do Campo, São Paulo State, and the relationship between these events to the physical environment for the establishment of future studies in other cities.

Tung Wai Lan, Iris. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 92-101. / ACKNOWLEDGEMENTS / ABSTRACT / LIST OF FIGURES --- p.iii / LIST OF TABLES --- p.iv / CHAPTER / Chapter I --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Significance of the Research --- p.3 / Chapter 1.3 --- Objectives of the Research --- p.5 / Chapter 1.4 --- Organization of the Research --- p.5 / Chapter II --- LITERATURE REVIEW --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Development of Long-Range Forecasting Technique --- p.8 / Chapter 2.3 --- Available Techniques of Long-Range Forecast --- p.9 / Chapter 2.3.1 --- Analogs and persistence --- p.10 / Chapter 2.3.2 --- Statistical modelling --- p.12 / Chapter 2.3.3 --- Atmosphere-ocean interaction --- p.17 / Chapter 2.3.4 --- Cycles and time series --- p.18 / Chapter 2.3.5 --- Numerical modelling --- p.19 / Chapter 2.4 --- Rainfall Prediction in Hong Kong --- p.21 / Chapter III --- RAINFALL OF HONG KONG --- p.24 / Chapter 3.1 --- Climatic Feature --- p.24 / Chapter 3.2 --- The Causes of Hong Kong Rainfall --- p.26 / Chapter 3.2.1 --- Tropical cyclone --- p.26 / Chapter 3.2.2 --- Trough or front --- p.28 / Chapter IV --- METHODOLOGY --- p.31 / Chapter 4.1 --- Introduction --- p.31 / Chapter 4.2 --- Empirical Orthogonal Function (EOF) Analysis --- p.32 / Chapter 4.2.1 --- What's EOF --- p.32 / Chapter 4.2.2 --- Why use EOF --- p.34 / Chapter 4.3 --- Discriminant Analysis --- p.36 / Chapter 4.4 --- Data Base --- p.37 / Chapter 4.5 --- Computation Procedures --- p.40 / Chapter 4.6 --- Analysis of Forecast Capability --- p.44 / Chapter V --- THE RESULT AND ANALYSIS OF PREDICTION MODEL --- p.48 / Chapter 5.1 --- The result of EOF analysis --- p.48 / Chapter 5.1.1 --- Extraction of eigenvectors and eigenvalues --- p.48 / Chapter 5.1.2 --- Spatial and Temporal variation of eigenvector pattern --- p.52 / Chapter 5.2 --- Accuracy of the prediction model --- p.53 / Chapter 5.2.1 --- Introduction --- p.53 / Chapter 5.2.2 --- The forecast accuracy from each month --- p.54 / Chapter 5.2.2.1 --- The forecast accuracy made by October --- p.54 / Chapter 5.2.2.2 --- The forecast accuracy made by November --- p.56 / Chapter 5.2.2.3 --- The forecast accuracy made by December --- p.58 / Chapter 5.2.2.4 --- The forecast accuracy made by January --- p.58 / Chapter 5.2.2.5 --- The forecast accuracy made by February --- p.61 / Chapter 5.2.2.6 --- The forecast accuracy made by March --- p.61 / Chapter 5.2.2.7 --- The forecast accuracy made by April --- p.64 / Chapter 5.2.3 --- Optimal length of dependent data --- p.64 / Chapter 5.2.4 --- Analysis the prediction results --- p.67 / Chapter 5.2.5 --- Comparison between the method used in this study with those methods adopted by ROHK --- p.69 / Chapter 5.2.5.1 --- Introduction --- p.69 / Chapter 5.2.5.2 --- Comparison of the forecast accuracy between two studies --- p.70 / Chapter VI --- CONCLUSION --- p.73 / Chapter 6.1 --- Summary of Findings --- p.73 / Chapter 6.2 --- Limitations of the Research --- p.75 / Chapter 6.3 --- Prospects of the Research --- p.76 / APPENDICES --- p.78 / LIST OF CITED REFERENCES --- p.92 / LIST OF READING MATERIALS --- p.97

Policy makers, water managers, farmers and many other sectors of the society in southern Africa are confronting increasingly complex decisions as a result of the marked day-to-day, intra-seasonal and inter-annual variability of climate. Hence, forecasts of hydro-climatic variables with lead times of days to seasons ahead are becoming increasingly important to them in making more informed risk-based management decisions. With improved representations of atmospheric processes and advances in computer technology, a major improvement has been made by institutions such as the South African Weather Service, the University of Pretoria and the University of Cape Town in forecasting southern Africa’s weather at short lead times and its various climatic statistics for longer time ranges. In spite of these improvements, the operational utility of weather and climate forecasts, especially in agricultural and water management decision making, is still limited. This is so mainly because of a lack of reliability in their accuracy and the fact that they are not suited directly to the requirements of agrohydrological models with respect to their spatial and temporal scales and formats. As a result, the need has arisen to develop a GIS based framework in which the “translation” of weather and climate forecasts into more tangible agrohydrological forecasts such as streamflows, reservoir levels or crop yields is facilitated for enhanced economic, environmental and societal decision making over southern Africa in general, and in selected catchments in particular. This study focuses on the development of such a framework. As a precursor to describing and evaluating this framework, however, one important objective was to review the potential impacts of climate variability on water resources and agriculture, as well as assessing current approaches to managing climate variability and minimising risks from a hydrological perspective. With the aim of understanding the broad range of forecasting systems, the review was extended to the current state of hydro-climatic forecasting techniques and their potential applications in order to reduce vulnerability in the management of water resources and agricultural systems. This was followed by a brief review of some challenges and approaches to maximising benefits from these hydro-climatic forecasts. A GIS based framework has been developed to serve as an aid to process all the computations required to translate near real time rainfall fields estimated by remotely sensed tools, as well as daily rainfall forecasts with a range of lead times provided by Numerical Weather Prediction (NWP) models into daily quantitative values which are suitable for application with hydrological or crop models. Another major component of the framework was the development of two methodologies, viz. the Historical Sequence Method and the Ensemble Re-ordering Based Method for the translation of a triplet of categorical monthly and seasonal rainfall forecasts (i.e. Above, Near and Below Normal) into daily quantitative values, as such a triplet of probabilities cannot be applied in its original published form into hydrological/crop models which operate on a daily time step. The outputs of various near real time observations, of weather and climate models, as well as of downscaling methodologies were evaluated against observations in the Mgeni catchment in KwaZulu-Natal, South Africa, both in terms of rainfall characteristics as well as of streamflows simulated with the daily time step ACRU model. A comparative study of rainfall derived from daily reporting raingauges, ground based radars, satellites and merged fields indicated that the raingauge and merged rainfall fields displayed relatively realistic results and they may be used to simulate the “now state” of a catchment at the beginning of a forecast period. The performance of three NWP models, viz. the C-CAM, UM and NCEP-MRF, were found to vary from one event to another. However, the C-CAM model showed a general tendency of under-estimation whereas the UM and NCEP-MRF models suffered from significant over-estimation of the summer rainfall over the Mgeni catchment. Ensembles of simulated streamflows with the ACRU model using ensembles of rainfalls derived from both the Historical Sequence Method and the Ensemble Re-ordering Based Method showed reasonably good results for most of the selected months and seasons for which they were tested, which indicates that the two methods of transforming categorical seasonal forecasts into ensembles of daily quantitative rainfall values are useful for various agrohydrological applications in South Africa and possibly elsewhere. The use of the Ensemble Re-ordering Based Method was also found to be quite effective in generating the transitional probabilities of rain days and dry days as well as the persistence of dry and wet spells within forecast cycles, all of which are important in the evaluation and forecasting of streamflows and crop yields, as well as droughts and floods. Finally, future areas of research which could facilitate the practical implementation of the framework were identified. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

[Truncated abstract] Pesticides are often transported to streams and/or groundwater as a result of the occurrence of rainfall events which trigger surface runoff or rapid preferential flow through the unsaturated zone. Much of the theory of solute transport has been derived assuming steady state or slowly varying upper boundary conditions and continuous, averaged process descriptions. However, a review of pesticide dynamics reveals that pesticides are episodically transported, predominantly through discrete flow pathways and this transport is often initiated as a near surface process, driven by naturally variable and intermittent rainfall intensities. The objective of the thesis is to better understand how the structure of natural variability of rainfall intensities impacts upon pesticide transport by these fast flow processes. We first conducted an analysis of a lysimeter leaching experiment that was aimed at identifying the rainfall controls on herbicide transport. Multivariate analyses revealed that average water balance behaviour at low temporal resolution controlled water and bromide transport while extreme rainfall events and rainfall event frequency controlled herbicide transport. A minimalist event based modelling approach was able to simulate the observed herbicide transport without or with only minor calibration. ... Finally we conduct a climate based regional risk assessment of pesticide leaching for the Wheatbelt region of the south-west of Western Australia. This is done for a suite of pesticides on a single soil to evaluate the impact of rainfall variability alone. Moderately sorbing, slowly degrading solutes have a greater regional potential for rapid leaching than both strongly and weakly sorbing solutes. High leaching potentials are found along the western and southern coast and in the far-east, with a band of low leaching potential through the central Wheatbelt. This is despite higher annual rainfall in the central areas compared to the east, and it is found that this occurs because of a change in the dominant fast flow triggers from frequent low intensity rainfall on the coasts to high intensity infrequent storms in the east. The coefficient of variation of annual leaching loads is similarly distributed. Spatial patterns of leaching potential depend upon chemical properties and application time. Peak loads of chemicals to fast flow pathways are found to converge to mid-winter, indicating periods of high loads of multiple pesticides may be an unavoidable consequence of the seasonality of storm properties.

A frequente ocorrência de desastres naturais gera impactos sociais e econômicos cada vez maiores, impondo a necessidade de elaborar estratégias de prevenção e redução de riscos. No cenário nacional, os desastres causados por eventos hidrológicos representam a maior parte das ocorrências. Acidentes de maior exposição e maiores consequências são os ocasionados por movimentos gravitacionais de massa. Assim, as iniciativas de prevenção de desastres necessariamente passam pelo detalhamento do conhecimento do problema, o que deve orientar o estabelecimento de metas de ações de redução de risco, instrumentos de gestão e resposta, e ainda para sistemas de monitoramento e alerta. Estes sistemas necessariamente devem contar com mapeamentos dos locais de risco, rede de coleta de dados meteorológicos que subsidiem previsões de eventos hidrológicos, e o estabelecimento dos limiares críticos de chuva deflagradores de escorregamentos. Com tais objetivos, órgãos governamentais promoveram esforços no mapeamento dos riscos, em escalas adequadas, e o investimento na estruturação de redes de monitoramento hidrometeorológico, sendo necessárias iniciativas de elaboração de limiares críticos regionalizados a serem amplamente desenvolvidas. Dentro do cenário da gestão de riscos descritos, este trabalho teve como principal objetivo a determinação de limiares críticos de chuva deflagradores de movimentos gravitacionais de massa no município de São Bernardo do Campo. Baseando-se na avaliação dos dados de série histórica de pluviometria, e de um banco de dados formado a partir das ocorrências de escorregamentos atendidas no município, compreendendo 415 escorregamentos ao longo de 24 anos (1993 a 2016). Os resultados da correlação dos dados do meio físico, da pluviometria e das ocorrências de escorregamentos, permitiram uma série de análises da distribuição das ocorrências. A distribuição foi feita ao longo do tempo, em função de acumulados de chuva e em função dos aspectos do meio físico. Foram feitas também correlações da intensidade das chuvas em função da espacialização e acumulados de chuva. As correlações espaciais dos dados permitiram o estabelecimento de uma ferramenta que relaciona as caracterizações do meio físico com as ocorrências de escorregamentos, que foi denominado como Coeficiente de Ocorrências por Área (COPA). Este coeficiente indicou os elementos do meio físico de maior influência na deflagração de movimentos de massa na área de estudo, em ordem de prioridade os destaques foram: 1) muito alta densidade de ocupação; 2) padrões e morfologias de relevo de morros altos e morros baixos; 3) alta densidade de ocupação; 4) unidade geológica do Micaxisto; e 5) terrenos com inclinação superior a 25°. Destaca-se que o trabalho contribuiu para o conhecimento da resposta dos elementos de frente a processos hidrometeorológicos e para a definição de limiares críticos de chuva deflagradora de escorregamentos, determinando uma equação numérica de previsão de ocorrências a partir dos dados pluviométricos e de previsões meteorológicas. Estes resultados também puderam contribuir no estabelecimento de parâmetros técnico-científicos para refinar a gestão do risco de movimentos de massa em São Bernardo do Campo-SP, e das relações desses eventos com o meio físico para estabelecimento de estudos em outras localidades. / The frequent occurrence of landslides in Brazil has been the cause of larger issues, economically and socially, which explains the necessity to elaborate preventing strategies in order to reduce such risks to the population. Looking at the Brazilian panorama, the disasters caused by hydrological events represent the greater part of these occurrences. Mass gravitational movements cause accidents of a bigger exposure and have greater consequences. Thus, the prevention strategies must go through a detailed study, in order to gather knowledge to better understand the problem as a whole; this information must orientate the establishment of targets for risk reduction actions, management and response instruments, as well as the monitoring and alert systems. These systems must have risk mapping and meteorological data collection networks, in order to predict hydrological events and establish critical limits to landslides caused by rainfall. With these bjectives, government agencies have promoted efforts to map these areas in adequate scales, as well as investing and structuring hydrometereological monitoring networks, requiring initiatives to elaborate regionalized critical groundsels to be extensively developed. Within the scenario of risk management described, this study has the objective to determine critical thresholds triggered by rainfall of mass gravitational movements at the municipality of Sao Bernardo do Campo. Based on the evaluation of the historical data of rainfall, and database gathered from the occurrences of landslides that took place in the same municipality as well as, comprising 415 landslides that have happened for over 24 years (from 1993 to 2016). The correlated results in the physical environment data on occurrences of landslides caused by rainfall, started a series of analyzes on the distribution of these occurrences. This distribution was made throughout the described timeline, due to accumulated rain damage and other environmental aspects. Correlations on the rainfall intensity were also made due to the spacing of the damaged land. This spacing correlated data allowed the establishment of a tool that relates the characterizations of the environment with the gathered data on landslides, which was named as the Coefficient of Occurrences per Area (COPA). This coefficient indicates the physical environment elements, and had the greatest influence on the deflagration of mass movements at the studied area. In priority order, the emphasized topics were: 1) very high density of land occupation; 2) landforms high hills and low hills; 3) high density of land occupation; 4) geological unity of Mica Schist; and 5) terrains with an inclination higher than 25°. This study contributes to the knowledge on how the physical environment elements reacts ahead of hydrometeorological processes and to the definition of critical limits of rainfall that triggers landslides. Also, it has determined a numerical equation to landslides prediction from rainfall data and meteorological forecast. All these results could also contribute to the establishment of technical-scientific parameters, refining mass movement risk management at the city of São Bernardo do Campo, São Paulo State, and the relationship between these events to the physical environment for the establishment of future studies in other cities.

No description available.