This thesis deals with different kinds of floods and flood control measures that contribute to the alleviation of human and material losses during flood conditions.This paper outlines the main theoretical concepts on the subject of the flood, the reader is familiar with crisis situations and also with the recommended procedure, How to behave during a flood. The practical part includes a choice of two areas, their detailed characterization, description built flood protection measures and their ability to intercept and divert excessive and prolonged rainfall on agricultural land and urban areas. The work is also a number of tables, figures and photos for a better idea and understanding of the topic. The list of references from which it was drawn is given in the final part.

This thesis deals with flood maps and their use in the context of property insurance. There are flood maps presented in comparison with similar projects of the European Union, the flood hazard maps and flood risk maps. There is also assessed the impact of flood maps on Flood Prevention Strategy in the Czech Republic. This thesis analyzes the offers insurance companies in the property insurance according to 4 risk flood zones. Finally, it evaluates the importance of flood maps not only from the perspective of insurance companies, but also from the perspective of others (people, companies etc.).

Thesis (Ph. D. (Statistics)) -- University of Limpopo, 2016. / Statistics of extremes has seen much growth both in theory and application since its early theoretical developments almost a century ago in the 1920s and its first major applications to real-life problems pioneered by Emil Gumbel in the early 1940s. Although the theory and applications of extreme value theory (EVT) have been extensively advanced and utilised in most developed countries,intermsofapplicationslittlehasbeendoneinmanydevelopingcountries in Africa despite the abundance of areas of applications and raw data in some ofthesecountries. Inhydrology,thechoiceoffloodfrequencyprobabilitydistributions for a particular site or region remains the subject of ongoing research. The work contained in this thesis is a contribution towards this area and it addresses this problem in one of the developing and economically challenged countries in Africa, Mozambique, in the lower Limpopo River basin (LLRB). The LLRB is a basin characterised by extreme natural hazards, alternating between extreme floods and severe droughts. ThisthesisisbasedonanextensiveapplicationofEVTtoextremefloodheights data in the LLRB of Mozambique at three sites: Chokwe, Combomune and Sicacate hydrometric stations. Two fundamental approaches of EVT, block maxima and peaks-over-threshold (POT), are used in this thesis. Recent theoretical results by Ferreira and de Haan (2015) have shown that despite its inefficiency due to data lost as a result of blocking, the block maxima approach is more efficient in a number of situations than the POT approach, and the two approaches are quite comparable for large sample sizes. A number of ii candidate distributions are investigated for their goodness-of-fit to the annual daily maximum flood heights in a block maxima realisation at each site. The findings reveal that the GEV distribution is the most appropriate distribution to apply in the LLRB and the distribution can be recommended as the likelihood function for regional and spatial extremes flood frequency analysis in the basin. The thesis addresses the issue of cumulative effects on daily flood heights through a comparative analysis of six annual maxima moving sums. The findings demonstrate that the six annual maxima time series models are notsignificantlydifferentbasedonthecharacteristicsconsideredinthisthesis. In an attempt to reduce uncertainties in the estimates, a Bayesian Markov chain Monte Carlo (MCMC) approach with a conjugate prior and a GEV likelihood function is used to model the tails of the extreme flood heights in the basin. The findings reveal that the addition of prior information in Bayesian MCMC substantially reduces uncertainties in the estimates and improves precision in the predicted extreme floods. The r largest order statistics models developed in this thesis are generally promising and the standard errors of the estimates of the parameters are substantially reduced. In order to account for climate change impact, nonstationary models are considered with the longterm trend and seasonal oscillation index (SOI) (a meteorological variable indicator) as covariates of the parameters of the GEV distribution and the generalised Pareto distribution (GPD). Among the major contributions of this thesis is a proposed procedure for the determination of the 8 days window period used in extracting independent r largest order values within the same year for the r largest order statistics approach. A summary of the key findings and contributions of this thesis are given in Chapter 9. Moreover, contributions by the study topic in each chapter are given at the end of each chapter. / DST-NRF Centre of Excellence in Mathematical and Statistical Sciences (CoEMaSS) of South Africa

No / We propose a new dynamic simulation scheme for large-scale flood hazard modelling and prevention. The approach consists of a number of core parts: Digital terrain modelling with GIS data, Nona-tree space partitions (NTSP), Automatic River object recognition and registration, and a flood spreading model. The digital terrain modelling method allows the creation of a geometric real terrain model for augmented 3D environments with very large GIS data, and it can also use information gathered from aviation and satellite images with a ROAM algorithm. A spatial image segmentation scheme is described for river and flood identification and for a 3D terrain map of flooding region growth and visualisation. The region merging is then implemented by adopting Flood Region Spreading Algorithm (FRSA). Compared with the conventional methods, our approach has the advantages of being capable of realistically visualising the flooding in geometrically-real 3D environments, of handling dynamic flood behaviour in real-time and of dealing with very large-scale data modelling and visualisation.

Geosynthetic tubes filled with water are considered. The tubes can be used in applications to resist rising floodwaters. They can also be used to form breakwaters and protect shores from erosion. This thesis considers single and stacked tubes resting on a rigid and deformable foundation resisting rising hydrostatic headwater. Experiments were carried out to determine the behavior of a three-tube stacked configuration resting on a sand foundation. This study was a continuation of previous work on unstacked tubes. Many tests were performed to determine the deformation and stability of the system. A geosynthetic drain was placed beneath the tubes to prevent piping. The objective was to cause failure of the system in a sliding manner and formulate a hypothesis according to the placement of the drain beneath the tubes. In order to cause a sliding failure, a strapping system was developed to try and prevent the tubes from rolling. A single tube at rest, filled with water but with no external hydrostatic pressure, was considered for analysis first. The tube rested on a rigid foundation and was assumed to be infinitely long. The friction between the tube and the foundation was neglected, and the bending stiffness of the tube was assumed to be negligible. The tube material was assumed to be inextensible. Mathematica was used to solve the system of equations and compute the unknowns. Excel was used to plot the data and observe the behavior of the tubes. An analysis was also performed on a single tube with an apron attached, resting on a rigid foundation. The apron was attached on the rising headwater side to increase stability. The assumptions for the tube at rest were also applied in this analysis. Two cases were derived and analyzed: a case where the internal hydrostatic pressure remains constant, and a case where the cross-sectional area remains constant. For the second case, the internal pressure changes as the floodwater level rises. The results from this study demonstrated that water-filled tubes, stacked or with an apron attached, can be an effective alternative method to sandbags in resisting floodwaters. / Master of Science

Floods are natural phenomena which are a threat to human settlements. Flooding can result in costly repairs to buildings, loss of business and, in some cases, loss of life. The forecasts for climate change show a further increased risk of flooding in future years. Accordingly, the flooding of residential property has been observed as on the rise in the UK. It is difficult to prevent floods from occurring, but the effects of flooding can be managed in an attempt to reduce risks and costs of repair. This can be achieved through ensuring a good understanding of the problem, and thereby establishing good management systems which are capable of dealing with all aspects of the flood. The use of an intelligent system for assessment and remediation of buildings subjected to flooding damage can facilitate the management of this problem. Such a system can provide guidance for the assessment of vulnerability and the repair of flood damaged residential buildings; this could save time and money through the use of the advantages and benefits offered by knowledge base systems. A prototype knowledge base system has been developed in this research. The system comprises three subsystems: degree of vulnerability assessment subsystem; remediation options subsystem; and foundation damage assessment subsystem. The vulnerability assessment subsystem is used to calculate the degree of vulnerability, which will then be used by the remediation options subsystem to select remediation options strategy. The vulnerability assessment subsystem can subsequently be used to calculate the degree to which the building is vulnerable to damage by flooding even if it is not flooded. Remediation options subsystem recommended two strategy options: either ordinary remediation options in the case of vulnerability being low or, alternatively, resilience remediation options in the case of vulnerability being high. The foundation damage assessment subsystem is working alone and is used to assess the damage caused by flooding to the building s foundation, and to thereby recommend a repair option based on the damage caused and foundation type. The system has been developed based on the knowledge acquired from different sources and methods, including survey questionnaires, documents, interviews, and workshops. The system is then evaluated by experts and professionals in the industry. The developed system makes a contribution in the management and standardisation of residential building flooded damage and repair.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The Francou and Rodier (1967) empirical approach uses the original concept of envelope curves for the definition of the regional maximum flood (RMF). Kovacs (1980) adopted the Francou and Rodier empirical flood calculation method and applied it to 355 catchments in South Africa. He revised his study in 1988 to also include the southern portions of the Southern Africa subcontinent. No method other than the Francou and Rodier empirical flood approach in the reviewed literature was found to be suitable for the purpose of this study. Therefore the Francou and Rodier empirical approach, as applied by Kovacs in 1988, was reapplied and used in this study to update the RMF for Lesotho. Maximum recorded flood peaks were derived from annual maximum time series and an up to date catalogue of flood peaks for 29 catchments was compiled for Lesotho. The maximum recorded flood peaks were then plotted on the logarithmic scale against their corresponding catchment areas. There are 3 major river systems that divide Lesotho into hydrologically homogenous basins. Envelope curves were drawn on the upper bound of the cloud of plotted points for these 3 river basins. These envelope curves represent the maximum flood peaks that can reasonably be expected to occur within the respective river basins in Lesotho. / AFRIKAANSE OPSOMMING: Francou en Rodier (1967) se empiriese benadering maak gebruik van die oorspronklike konsep van boonste limiet kurwes vir die definisie van die streeks maksimum vloed (SMV). Kovacs (1980) het die Francou en Rodier empiriese vloed berekening metode toegepas op 355 opvanggebiede in Suid-Afrika. Hy hersien sy studie in 1988 om ook die suidelike gedeeltes van die Suider-Afrikaanse subkontinent in te sluit. Geen ander metode as die Francou en Rodier empiriese vloed benadering is in die literatuur gevind wat as geskik aanvaar kan word vir die doel van hierdie studie nie. Daarom is die Francou en Rodier empiriese benadering, soos toegepas deur Kovacs in 1988, weer in hierdie studie toegepas en gebruik om die SMV metode vir Lesotho op te dateer. Maksimum aangetekende vloedpieke is verkry vanuit jaarlikse maksimum tyd-reekse en ʼn opgedateerde katalogus van vloedpieke vir 29 opvanggebiede saamgestel vir Lesotho. Die maksimum aangetekende vloedpieke is grafies aangetoon op logaritmiese skaal teenoor hul opvanggebiede. Daar is 3 groot rivierstelsels wat Lesotho in hidrologiese homogene gebiede verdeel. Boonste limiet kurwes is opgestel om die boonste grens van die gestipte punte vir hierdie 3 gebiede aan te toon. Hierdie krommes verteenwoordig die maksimum vloedpieke wat redelikerwys verwag kan word om binne die onderskeie rivierstelsels in Lesotho voor te kan kom.

Throughout history floods have been part of the human experience. They are recurring phenomena that form a necessary and enduring feature of all river basin and lowland coastal systems. In an average year, they benefit millions of people who depend on them. In the more developed countries, major floods can be the largest cause of economic losses from natural disasters, and are also a major cause of disaster-related deaths in the less developed countries. Flood disaster mitigation research was conducted to determine how remotely sensed data can effectively be used to produce accurate flood plain maps (FPMs), and to identify/quantify the sources of error associated with such data. Differences were analyzed between flood maps produced by an automated remote sensing analysis tailored to the available satellite remote sensing datasets (rFPM), the 100-year flooded areas "predicted" by the Flood Insurance Rate Maps, and FPMs based on DEM and hydrological data (aFPM). Landuse/landcover was also examined to determine its influence on rFPM errors. These errors were identified and the results were integrated in a GIS to minimize landuse / landcover effects. Two substantial flood events were analyzed. These events were selected because of their similar characteristics (i.e., the existence of FIRM or Q3 data; flood data which included flood peaks, rating curves, and flood profiles; and DEM and remote sensing imagery.) Automatic feature extraction was determined to be an important component for successful flood analysis. A process network, in conjunction with domain specific information, was used to map raw remotely sensed data onto a representation that is more compatible with a GIS data model. From a practical point of view, rFPM provides a way to automatically match existing data models to the type of remote sensing data available for each event under investigation. Overall, results showed how remote sensing could contribute to the complex problem of flood management by providing an efficient way to revise the National Flood Insurance Program maps.

This thesis examines the role of the public in Flood Risk Management (FRM) service provision at a time when the perceptions of the distribution of benefits provided by FRM interventions are in flux, and the role the public should play in FRM highly contested among stakeholders. Two schemes have marked the revised role of the public in FRM - Partnership Funding and Flood Re - both of which challenge existing judgments of the excludability and rivalry of benefits delivered by FRM interventions. The Partnership Funding scheme allocates capital for FRM projects proportionately to the public benefits they provide, allowing communities to top-up grants through local contributions. In comparison, by increasing accessibility to affordable insurance through cross-subsidies and pricing signals, Flood Re highlights a growing recognition that the distribution of gains as a result of widespread insurance uptake is greater than the benefits received by the policyholder alone. Following the identification of these schemes, we tested their social feasibility, examining both the scale and distribution of benefits. Due to the different stages of implementation of each scheme at the time of writing this thesis, two distinct methods were developed. The Partnership Funding Chapter used field data to examine how public-private funding of flood defences has changed service provision and the public acceptance of this transition. Whereas the Flood Re chapter used computer-based experiments to hypothesize how Flood Re may make the purchase of insurance a more or less attractive investment for different types of consumer. We found that Partnership Funding enabled more FRM projects to go ahead, raised public awareness of flood risk, and improved collaboration between stakeholders, but encouraged lower-cost projects, which, in the longer term, could transfer the expense of managing residual risk to the householder. In comparison, Flood Re provided peace of mind to householders struggling to afford rises in insurance premiums, but disproportionately benefited those who annually purchased insurance. Combining this proposed inequity in Flood Re with increasing residual risks, we identify a gap in service provision for the public who cannot afford household mitigation measures. We propose that loss mitigation and flood defence should become increasingly collaborative in line with the complexities of flooding within a community. We seek a move away from the information asymmetry which currently exists between insurance providers and policyholders, and yet simultaneously call for local authorities to recognise the capacity of the public to participate in FRM, and sustain resilience in the face of rising flood risk.

A model that emphasizes possible alternative sequences of events that occur over time is presented in paper 1 (chapter 2) of this dissertation. Representing alternative or branching events captures additional semantics unrealized by linear or non-branching approaches. Two basic elements of branching, divergence and convergence are discussed. From these elements, many complex branching models can be built capturing a perspective of events that take place in the future or have occurred in the past. This produces likely sequences of events that a user may compare and analyze using spatial or temporal criteria. The branching events model is especially useful for spatiotemporal decision support systems, as decision-makers are able to identify alternative locations and times of events and, depending on the context, also identify regions of multiple possible events. Based on the formal model, a conceptual framework for a branching events model for flood disasters is presented. The framework has five parts, an event handler, a query engine, data assimilator, web interface, and event database. A branching events viewer application is presented illustrating a case study based on a flood response scenario. A spatiotemporal framework for building evacuation events is developed to forecast building content evacuation events and building vulnerabilities and is presented in paper 2 (chapter 3) of this dissertation. This work investigates the spatiotemporal properties required to trigger building evacuation events in the floodplain during a flood disaster. The spatial properties for building risks are based on topography, flood inundation, building location, building elevation, and road access to determine five categories of vulnerability, vulnerable basement, flooded basement, vulnerable first-floor, flooded first-floor, and road access. The amount of time needed to evacuate each building is determined by the number of vulnerable floors, the number of movers, the mover rate, and the weight of the contents to be moved. Based upon these properties, six possible evacuation profiles are created. Using this framework, a model designed to track the spatiotemporal patterns of building evacuation events is presented. The model is based upon flood forecast predictions that are linked with building properties to create a model that captures the spatiotemporal ordering of building vulnerabilities and building content evacuation events. Applicable to different communities at risk from flooding, the evacuation model is applied a historical flood for a university campus, demonstrating how the defined elements are used to derive a pattern of vulnerability and evacuation for a campus threatened by severe flooding. Paper 3 (Chapter 4) of this dissertation presents a modeling approach for representing event-based response risk. Surveys were sent to emergency managers in six states to determine the priorities of decision makers during the response phase of flood disasters. Based on these surveys, nine response events were determined to be the most important during a flood response, flooded roads, bridges closed, residential evacuations, residential flooding, commercial flooding, agricultural damage, power outage, sheltering, sandbagging. Survey participants were asked to complete pairwise comparisons of these nine events. An analytic hierarchy process analysis was completed to weight the response events for each decision-maker. A k-means clustering analysis was then completed to form 4 distinct profiles, mixed rural and urban, rural, urban, and high population - low population density. The average weights from each profile were calculated. The weights for each profile were then assigned to geospatial layers that identify the locations of these events. These layers are combined to form a map representing the event-based response risk for an area. The maps are then compared against the response events that actually occurred during a flood disaster in June 2008 in two communities.