Thesis (M. Sc. (Statistics)) -- University of Limpopo, 2021 / The effects of ozone depletion on climate change has, in recent years, become a reality, impacting on changes in rainfall patterns and severity of extreme floods or extreme droughts. The majority of people across the entire African continent live in semi-arid and drought-prone areas. Extreme droughts are prevalent in Somalia and eastern Africa, while life-threatening floods are common in Mozambique and some parts of other SADC (Southern African Development Community) countries. Research has cautioned that climate change in South Africa might lead to increased temperatures and reduced amounts of rainfall, thereby altering their timing and putting more pressure on the country’s scarce water resources, with implications for agriculture, employment and food security. The average annual rainfall for South Africa is about 464mm, falling far below the average annual global rainfall of 860mm. The Limpopo Province, which is one of the nine provinces in South Africa, and of interest to this study, is predominantly agrarian, basically relying on availability of water, with rainfall being the major source for water supply. It is, therefore, pertinent that the rainfall pattern in the province be monitored effectively to ascertain the rainy period for farming activities and other uses. Modelling and forecasting rainfall have been studied for a long time worldwide. However, from time to time, researchers are always looking for new models that can predict rainfall more accurately in the midst of climate change and capture the underlying dynamics such as seasonality and the trend, attributed to rainfall. This study employed Exponetial Smoothing (ETS) State Space and Seasonal Autoregressive Integrated Moving Average (SARIMA) models and compared their forecasting ability using root mean square error (RMSE). Both models were used to capture the sporadic behaviour of rainfall. These two models have been widely applied to climatic data by many scholars and adjudged to perform creditably well. In an attempt to find a suitable prediction model for monthly rainfall patterns in Limpopo Province, data ranging from January 1900 to December 2015, for seven weather stations: Macuville Agriculture, Mara Agriculture, Marnits, Groendraal, Letaba, Pietersburg Hospital and Nebo, were analysed. The results showed that the two models were adequate in predicting rainfall patterns for the different stations in the Limpopo Province. / National Research Foundation (NRF)

Bakgrund: Klimatförändringarnas effekter globalt som på lokal nivå, kan redan noteras. För skyfallsöversvämningar har det ökat och kommer öka än mer framöver. Olika sektorer i ett samhälle påverkas när en stad översvämmas, varav en stor grupp består av samhällets medborgare. Individer upplever skyfall som oförutsägbara och slumpmässiga. Konsekvenserna efter en skyfallsöversvämning har effekt på både de sociotekniska och socioekonomiska dimensionerna för en individ på kort och lång sikt. Med detta perspektiv anses det intressant att undersöka hur individer resonerar kring framtida skyfallsöversvämningar på lokal nivå. Studien avgränsas till privata fastighetsägare, då tidigare forskning pekar på att de som äger sin egen bostad är mer benägna att anta skyddande anpassningar på sina enskilda fastigheter, vilket antas bidra till den totala samhällssäkerheten. Syftet: Syftet med studien var att öka förståelsen för privata fastighetsägares syn på skyfall som leder till översvämning och hur det motiverar dem att vilja skydda sin privata fastighet innan en översvämning sker. Metod: Studiens kvalitativa forskningsinriktning utgick från en hermeneutisk vetenskapsteori med inriktning åt samhälls- och beteendevetenskap. Datainsamlingen genomfördes som semi-strukturerade intervjuer som analyserades utifrån en kvalitativ konventionell innehållsanalysmetod med induktiv ansats. Totalt genomfördes sex kvalitativa intervjuer. Områdesurvalet utgick från ett strategiskt icke-sannolikhetsbaserat urval medan respondenturvalet var ett icke-slumpmässigt bekvämlighetsurval. En testintervju genomfördes innan själva studien påbörjades, för att säkerställa att frågorna var relevanta. Som teoretiskt ramverk valdes Protection motivation theory för att fånga upp likheter och skillnader i individers resonemang kopplat till skyfallsöversvämningar. Resultat: Det induktiva analysförfarandet resulterade i tre huvudkategorier och nio underkategorier. Förmågor, riskhantering och samhällspåverkan belyser olika perspektiv hur privata fastighetsägare resonerar kring sin kapacitet innan en skyfallsöversvämning sker. Kunskapsbrist och individnivån; intra- och interpersonlighet inverkar på individernas förmågor och beslut. Medan valet av anpassningar av fastigheten vägdes mellan kostnaden i relation till tid och nyttovärdet. Vidare pekade resultatet på att samhällspåverkan var bidragande till en känsla av utsatthet, detta främst inom ansvarsfördelning och information hos respondenterna då de upplevde ett beroendesamband till kommunen och försäkringsbolagen. Utmärkande för studien: Respondenterna upplever skyfallsöversvämningar som ett abstrakt fenomen, vilket påvisas av en uttalad kunskapsbrist kopplat till området. Vidare har tidsfaktorn tillsammans med ansvarskostnaden inverkan på hur nyttovärdet av en anpassning upplevs. Mest framträdande är hur den sociala omgivningen tillsammans med individens självförmåga kan påverka riskbedömning och hanteringsförmåga i relation till skyfallsöversvämningar. Slutligen upplever den undersökta populationen privata fastighetsägare samhällspåverkan i form av beroendesamband och utsatthet till både kommun och försäkringsbolag, vilket pekar på att individperspektivet med inriktning på hantering av skyfallsrisker bör inkluderas i framtida forskning. / Background: The effects of climate change globally as well as at the local level can already be noted. Pluvial flood events have increased and will increase even more in the future. Different sectors of a society are affected when a city is flooded, of which a large group consists of the citizens of the society. Individuals experience extreme rains as unpredictable and random. The consequences after pluvial floods have an effect on both the socio-technical and socio-economic dimensions of an individual in the short and long term. With this perspective it is considered interesting to do research, to capture how individuals reason about future pluvial floods, at the local level. The study is limited to private property owners, as previous research indicates that those who own their home are more aware and prone to adopt protective adaptations to protect their property, which is assumed to contribute to overall social security. Purpose: The aim of the study was to increase the understanding of private property owners´ views on pluvial floods that lead to flooding and how it motivates them to want to protect their private property before a flood occurs. Method: The qualitative research was based on a hermeneutic theory of science with a focus on social and behavioural sciences. The data collection was conducted as semi-structured interviews. The collected data material was analyzed by applying a qualitative conventional content analysis method with an inductive approach. A total of six qualitative interviews were conducted. The area of the sample was based on a strategic non-probability sample, while the respondent sample was a non-random convenience sample. A test interview was conducted before the actual study began, to ensure that the questions were relevant. The Protection Motivation Theory, was chosen as the theoretical framework to capture similarities and differences in the individuals´ reasoning, linked to pluvial floods. Results: The inductive analysis procedure resulted in three main categories and nine sub-categories. Abilities, risk management and societal impact shed light on perspectives on how private property owners’ reason about their abilities before a pluvial flood occurs. Lack of knowledge and the level of the individual; intra- and interpersonal levels affect individuals´ inner abilities and decisions. While the choice of adaptations of the property was weighed between the cost in relation to time and utility value. Furthermore, the results indicated that social impact was contributing to a feeling of vulnerability, mainly within the division of responsibilities and information among the respondents when they experienced a dependency relationship with the municipality and the insurance companies. Characteristic of the study: The respondents experience pluvial floods as an abstract phenomenon, which is expressed as a lack of knowledge linked to the area of research. Furthermore, the time factor together with the cost of liability has an impact on how the utility value of the adaptation measure is perceived. Most prominent is how the social environment together with the individual´s self-efficacy can affect risk assessment and coping ability in relation to pluvial floods. Finally, the surveyed population of private property owners’ experiences societal impact in the form of dependency and vulnerability to both municipality and insurance companies, which indicates that the individual perspective with a focus on managing pluvial flood risks, should be included in future research.

Disaster risk Reduction (DRR) is well known and practiced in many nations. Community Based Disaster Risk Reduction (CBDRR) is a sub-component of DRR which is slowly being practiced in most at risk communities. However, there are still gaps regarding the principles and guidelines that guide the process of CBDRR. This study stipulates numerous guiding principles that govern the processes of CBDRR activities. These are: traditional knowledge, understanding of community members, capacity of community members, community participation, political will and training of community members. Furthermore the study used the guidelines to evaluate which activities by the Oshakati community members relate to the principles and guidelines of CBDRR as a way of reducing the risk of recurring floods in the community. Through focus group discussions and semi-structured individual interviews, it was found that the community members in Oshakati adhere to most principles of CBDRR such as the use of traditional knowledge, community members having the capacity to work together to solve common societal problems and to understand community structures. However, guidelines such as community participation, political will and training of community members were not adhered to due to various challenges such as the lack of institutional capacity and limited resources. The findings further stipulate that those guidelines were not adhered to due to inadequate knowledge on DRR and lack of support from the local government due to limited availability of resources. The study recommends that in order for the local government to reduce the risk of recurring floods in the community, the local government need to build capacity of its personnel working directly with DRR aspects. These can be achieved through a shift in the approach of responding to flooding to being proactive, creating awareness regarding the hazard and ensuring genuine participation of community members into local government CBDRR activities. / M Development and Management, North-West University, Potchefstroom Campus, 2015

Disaster risk Reduction (DRR) is well known and practiced in many nations. Community Based Disaster Risk Reduction (CBDRR) is a sub-component of DRR which is slowly being practiced in most at risk communities. However, there are still gaps regarding the principles and guidelines that guide the process of CBDRR. This study stipulates numerous guiding principles that govern the processes of CBDRR activities. These are: traditional knowledge, understanding of community members, capacity of community members, community participation, political will and training of community members. Furthermore the study used the guidelines to evaluate which activities by the Oshakati community members relate to the principles and guidelines of CBDRR as a way of reducing the risk of recurring floods in the community. Through focus group discussions and semi-structured individual interviews, it was found that the community members in Oshakati adhere to most principles of CBDRR such as the use of traditional knowledge, community members having the capacity to work together to solve common societal problems and to understand community structures. However, guidelines such as community participation, political will and training of community members were not adhered to due to various challenges such as the lack of institutional capacity and limited resources. The findings further stipulate that those guidelines were not adhered to due to inadequate knowledge on DRR and lack of support from the local government due to limited availability of resources. The study recommends that in order for the local government to reduce the risk of recurring floods in the community, the local government need to build capacity of its personnel working directly with DRR aspects. These can be achieved through a shift in the approach of responding to flooding to being proactive, creating awareness regarding the hazard and ensuring genuine participation of community members into local government CBDRR activities. / M Development and Management, North-West University, Potchefstroom Campus, 2015

<p>The main objective of this study is to understand and asses flood risk perception among people living in Msimbazi Valley in Das es Salaam, Tanzania. Many of the people I have interviewed are experiencing flooding every year but it is rarely considered disastrous. Looked at individually they may not be disasters but cumulatively they may be. The rapid urbanisation, in this part of the world, forces people to live on hazardous but central land because of the livelihood opportunities available there. The government and the local communities are well aware of the risk of floods in the area and are considered as a serious threat to the families. People are still living in these areas because they find the benefits big enough to make up the risks.</p>

Traditional flood-frequency techniques are based on the assumption that the observed flood record represents a sample that has been drawn from a single climatically homogeneous population of floods. A hydroclimatic approach was used to evaluate this assumption by identifying the circulation patterns and atmospheric flood-generating mechanisms which control the temporal and spatial variability of flooding. Mean monthly discharges and instantaneous peak flows of the partial duration series were analyzed for thirty gaging stations in the climatically sensitive, semiarid, Gila River basin for the period 1950 to 1980. Correlation fields and composite maps were constructed to define the relationship between 700 mb height circulation anomalies and mean monthly streamflow. Individual flood events were linked to climate by analyzing daily synoptic weather maps and classifying each flood event into one of eight hydroclimatic categories on the basis of the atmospheric mechanisms which generated each flow. The analysis demonstrated that floods and anomalously high streamflow in the Gila River basin originate from a variety of atmospheric processes which vary spatially, seasonally, and from year-to-year. The mechanisms most important for generating floods included winter fronts, cutoff lows, tropical storms, snowmelt, and widespread and localized summer monsoon-related circulation patterns. When flood discharges were grouped into hydroclimatically homogeneous categories, histogram plots of their frequency distributions exhibited means and variances that differed from those of the overall frequency distribution of the entire flood series. The means of the discharges generated by frontal precipitation and tropical storms tended to plot above the mean of the overall series, while the means of floods generated by snowmelt tended to plot below the overall mean. Flood estimates computed from a series containing mixed distributions were not the same as flood estimates computed from climatically homogeneous subsets of the same series. These results have implications for traditional flood-frequency analysis and other stochastic methods of analyzing hydrologic time series. The hydroclimatically-defined subgroups in the flood series of the Gila River basin indicate that nonhomogeneity and nonstationarity can be imparted to a hydrologic time series by differing atmospheric mechanisms alone.

The aim of this research project was to estimate parameters for the distribution of annual maximum flood levels for the Zambezi River at Katima Mulilo. The estimation of parameters was done by using the maximum likelihood method. The study aimed to explore data of the Zambezi's annual maximum flood heights at Katima Mulilo by means of fitting the Gumbel, Weibull and the generalized extreme value distributions and evaluated their goodness of fit.

The objective of this thesis was to design a canister for the disposal of spent nuclear fuel and other high-level waste in deep borehole repositories using currently available and proven oil, gas, and geothermal drilling technology. The canister is suitable for disposal of various waste forms, such as fuel assemblies and vitrified waste. The design addresses real and perceived hazards of transporting and placing high-level waste, in the form of spent reactor fuel, into a deep igneous rock environment with particular emphasis on thermal performance. The proposed boreholes are 3 to 5 km deep, in igneous rock such as granite. The rock must be in a geologically stable area from a volcanic and tectonic standpoint, and it should have low permeability, as shown in recent data taken from a Russian deep borehole. Although deep granite should remain dry, water in flooded boreholes is expected to be reducing, but potentially corrosive to steel. However, the granite and plug are the containment barrier, not the canister itself. The canisters use standard oil drilling casings. The inner diameter is 315.32mm in order to accommodate a PWR assembly with a width of 214mm. At five meters tall, each canister holds one PWR assembly. The canister thickness is 12.19mm, with an outer diameter of 339.7mm. A liner can extend to the bottom of the emplacement zone to aid in retrievability. The liner has an outer diameter of 406.4mm and a thickness of 9.52mm. The standard drill bit used with a liner of this size has an outer diameter of 444.5mm. / Contract number: N62271-97-6-0026. / US Navy (USN) author.

Dans les régions méditerranéennes françaises, des épisodes pluvieux diluviens se produisent régulièrement et provoquent des crues très rapides et volumineuses que l'on appelle crues éclair. Elles font fréquemment de nombreuses victimes et peuvent, sur un seul évènement, coûter plus d'un milliard d'euros. Face à cette problématique, les pouvoirs publics mettent en place des parades parmi lesquelles la prévision hydrologique tient une place essentielle.C'est dans ce contexte que le projet BVNE (Bassin Versant Numérique Expérimental) a été initié par le SCHAPI (Service Central d'Hydrométéorologie et d'Appui à la Prévision des Inondations) dans le but d'améliorer la prévision des crues rapides. Ces travaux s'inscrivent dans le cadre de ce projet et ont trois objectifs principaux : réaliser des prévisions sur des bassins capables de ces réactions qu'ils soient correctement jaugés, mal jaugés ou non jaugés.La zone d'étude choisie, le massif des Cévennes, concentre la majorité de ces épisodes hydrométéorologiques intenses en France. Ce mémoire la présente en détails, mettant en avant ses caractéristiques les plus influentes sur l'hydrologie de surface. Au regard de la complexité de la relation entre pluie et débit dans les bassins concernés et de la difficulté éprouvée par les modèles à base physique à fournir des informations précises en mode prédictif sans prévision de pluie, l'utilisation de l'apprentissage statistique par réseaux de neurones s'est imposée dans la recherche d'une solution opérationnelle.C'est ainsi que des modèles à réseaux de neurones ont été synthétisés et appliqués à un bassin de la zone cévenole, dans des contextes bien et mal jaugés. Les bons résultats obtenus ont été le point de départ de la généralisation à 15 bassins de la zone d'étude. A cette fin, une méthode de généralisation est développée à partir du modèle élaboré sur le bassin jaugé et de corrections estimées en fonction des caractéristiques physiques des bassins. Les résultats de l'application de cette méthode sont de bonne qualité et ouvrent la porte à de nombreux axes de recherche pour l'avenir, tout en démontrant encore que l'utilisation de l'apprentissage statistique pour l'hydrologie peut constituer une solution pertinente. / In the French Mediterranean regions, heavy rainfall episodes regularly occur and induce very rapid and voluminous floods called flash floods. They frequently cause fatalities and can cost more than one billion euros during only one event. In order to cope with this issue, the public authorities' implemented countermeasures in which hydrological forecasting plays an essential role.In this contexte, the French Flood Forecasting Service (called SCHAPI for Service Central d'Hydrométéorologie et d'Appui à la Prévision des Inondations) initiated the BVNE (Digital Experimental Basin, for Bassin Versant Numérique Expérimental) project in order to enhance flash flood forecasts. The present work is a part of this project and aim at three main purposes: providing flash flood forecasts on well-gauged basins, poorly gauged basins and ungauged basins.The study area chosen, the Cévennes range, concentrates the major part of these intense hydrometeorological events in France. This dissertation presents it precisely, highlighting its most hydrological-influent characteristics.With regard to the complexity of the rainfall-discharge relation in the focused basins and the difficulty experienced by the physically based models to provide precise information in forecast mode without rainfall forecasts, the use of neural networks statistical learning imposed itself in the research of operational solutions.Thus, the neural networks models were designed and applied to a basin of the Cévennes range, in the well-gauged and poorly gauged contexts. The good results obtained have been the start point of a generalization to 15 basins of the study area.For this purpose, a generalization method was developed from the model created on the gauged basin and from corrections estimated as a function of basin characteristics.The results of this method application are of good quality and open the door to numerous pats of inquiry for the future, while demonstrating again that the use of statistical learning for hydrology can be a relevant solution.

The thesis focuses on how floods were covered in Czech newspapers. The approach taken by two periodicals, Mladá Fronta (MF DNES) and Rudé Právo (Právo), was compared on five examples of actual floods that took place in the Czech Republic and Czechoslovakia between 1954 - 2002. Examined was how the manner in informing about natural disasters differs between the period prior to 1989 and after, and how developments in technology contributed to the visual aspects of reporting on these events.