Flood events have caused detrimental impacts to humans' lives and anthropogenic climate change is anticipated to exacerbate the impact. It has been recognized that a long-term planning through risk-based optimization of flood defence will lead to a cost-effective solution for managing flood risk, but the prevailing assumption of stationarity may lead to an erroneous solution. In attempt to investigate the potential impact of the uncertain underlying statistical characteristics of extreme flow series to flood protection decisions, this research explores risk-based flood protection decisions in the context of climatic variability and change. In particular, the implications of persistence series and nonstationarity were investigated through hypothetical and real case studies. Monte Carlo simulation approach was adopted to capture the uncertainty due to the natural variability. For persistence model, AR(1) was integrated with the GEV model to simulate extreme flow series with persistence. To test the effects of nonstationary, GEV models with a linear location parameter and time as covariate were adopted. Rational decision makers' behaviours were simulated through a designed decision analysis framework. One of the main findings from the research is that the traditional stationary assumption should remain the basic assumption due to insignificant difference of the decisions' economic performance. However, exploration of the nonstationarity assumption enabled identification of options that are robust to climate uncertainties. It is also found that optimized protection of combined measures of flood defence and property-level protection may provide a cost-effective solution for local flood protection. Overall, the simulation and case studies enlighten practitioners and decision makers with new evidence, and may guide to practical enhancement of long term flood risk management decision making.

Flooding poses one of the greatest natural hazard dangers to Canadians. As human populations increase and concentrate in areas vulnerable to floods, and uncertainty about future flood risk increases with the possibility of a changing climate, major urban communities, coastal settlements and communities located within floodplains are faced with an even greater risk of floods in the coming years. Canada's policies and practices towards flood control are best described as ad hoc, and have developed over the years in response to experiences with floods. No national scale flood damage reduction program exists, and there is currently no opportunity for Canadian homeowners to purchase flood insurance. This study specifically examines how a national mitigation strategy, focused mainly on non structural techniques could help decrease damages from floods in Canadian communities. The strategy proposed here is theoretically based in EPC and IBC suggestions for a greater national mitigation strategy, as well as IDNDR research, and federal, provincial and municipal goals for sustainable development and sound land use planning objectives. Ideally, a successful non structural flood mitigation strategy for Canada would address issues at the national scale, yet be implementable at the local level in accordance with community needs, risk characteristics, and local expertise. The strategy proposed here would maximize the efficiency of federal resources and private industry as well as allow local expertise and existing mitigation schemes to be formalized, bolstered and improved. There are three major components of the non structural flood mitigation strategy. Risk avoidance measures such as early warning systems, land use and resource planning and ecological conservation all work towards reducing the chances of a dangerous flood occurring. Risk spreading measures help communities deal with flood risks by improving equity and accountability, they include tax incentives, disaster financial assistance, and flood insurance. Lastly, vulnerability reduction measures help reduce damages if a flood were to strike, and these include enforcement of building codes and the maintenance of existing protective infrastructure. An integrated, non structural flood mitigation strategy would require basin-wide cooperation between all levels of government, citizens and the private sector. This strategy is also an opportunity for communities and individuals to meet goals of environmental conservation and sustainable development. The focus in this study lies on the mitigation tools, although it is the overall process of inserting the premise of mitigation into all land use and planning decision making processes that will be the key to successful flood mitigation strategies in Canadian communities. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

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

Floods affect millions of people each year, with increasing frequency in the past decades. Floods, as any other natural phenomena, do not take place in a vacuum. Their impacts are modulated by the socioeconomic environments they affect, which are far from homogeneous and oftentimes characterized by deep disparities and inequalities. Ensuring sustainable development in a world where climate change is forecasted to increase the frequency and severity of flooding requires a nuanced understanding of these interactions between natural and socioeconomic systems. This dissertation sheds light on the impacts of flooding on economic outcomes of interest in two contrasting settings. First, Chapters 1 and 2 focus on the effects of flooding as a natural disaster in a developed country, the United States. Using evidence from Hurricane Sandy in 2012, these chapters explore how different neighborhoods, with different characteristics, responded to flooding. They conclude that heterogeneous responses led to an increased polarization along property value, racial, and income lines among neighborhoods. Then, Chapter 3 investigates the effects of seasonal flooding in the Malian Sahel. Unlike the previous setting, flooding brings about positive outcomes in this context, as livelihoods in this arid region are heavily dependent on surface water for agriculture. This chapter shows that lower seasonal flooding increases infant mortality. Thus, it provides evidence on the sort of long-term consequences that could affect low-income households after suffering short-lived resources shocks. Overall, this dissertation contributes to our understanding of the heterogeneous impacts of flooding. Increased awareness of these impacts would be key to formulate successful post-flood responses and policies to ensure future sustainable development.

No description available.

Floodplain is an important location for the economic and social development of society throughout history, although it afflicted by different disasters like floods and bank erosion from time to time. Population dynamics and distribution trends have important effects on the landscape and society. Population dynamics in floodplains influenced mostly by the flood events and related human activities to protect themselves and the properties. Thus, floodplain population dynamics is vital to understand human-nature relationships, disaster risk assessment, flood forecasting and flood damage costs in the floodplains. Economic losses and fatalities due to flood events increase with increased flood frequency and flood magnitude. Extreme hydrological changes are responsible for such changes in the flood events. Population growth, urbanization and developmental activities worsened the situation further in the floodplain areas. Learning effect, i.e. flood memory is noticeable after the flood which diminishes with time, however, levee, which is a popular flood protection measure, causes further reduction of learning effect. Researchers suggest that levees create a false sense of safety and can influence the mobilization of floodplain population. Several pieces of research indicate that along with flood events and intervention measures, inundation depth, durations, flood type (coastal/ riverine), economic, technological and political characteristics of the societies influence flood memory, hence, influence floodplain population dynamics. However, long term floodplain population dynamics and how it is related to different flood-related, i.e. hydrological and sociological variables are yet to be confirmed. Flood is one of the major natural disasters in the United States. About 10% of the population lives in the 100-year and 500-year floodplain of the United States. This study carried out to investigate the long-term trend of floodplain population dynamics in the USA and how the dynamics changes from country to state to county level considering Arkansas State and Sebastian County to observe the difference. Also, the relationships of floodplain population dynamics with hydrological and sociological variables such as flood events, damage, intervention measures and poverty assessed in the national, state and county level. Then the dynamics of the national level, the state (Arkansas) level and the county (Sebastian) level were compared to identify changes in dynamics from macro to micro-scale. Floodplain population dynamics evaluated in terms of population growth rate and the ratio of floodplain population to the total population from 1790 – 2010. The median centroids of the population growth rate from 1790 – 2010 were estimated to observe the changes in the central tendency of the population growth rate in the total area and in the floodplain overtime to locate the typical place of floodplain population growth. High-resolution raster image (1 km x 1 km) of historical population data and a high-resolution raster image (250 m x 250 m) of floodplain data were analysed using ArcGIS to evaluate floodplain population dynamics. Historical data regarding flood events, damage, structural and non- structural flood intervention measures and poverty from available databases were extracted, processed and analysed to establish the relationship among population dynamics, hydrological and social variables. Finally, the population dynamics of the three levels were compared statistically and discussed for changes. It is found that the central tendency of the total population growth rate and floodplain population growth rate of the USA shifts from east to west direction. The central tendency of the overall population growth rate located near the lower Mississippi river basin in the 1800s. It is consistent near the geographical centroid of the USA in Kansas since 1900. For the floodplain population, the central tendency of the growth rate stayed consistent in Arkansas from 1910 – 2010, i.e. in the lower Mississippi river basin. This location indicates the floodplains in Arkansas was preferable for floodplain population settlement for many decades. Change in floodplain population proportion of the whole country USA from 1790 – 2010 shows that the proportion of floodplain population is more than 80% during the initial years of settlement. Then it reduced to less than 40% over time. At the state level – Arkansas, the proportion of floodplain population is also more than 80% during initial settlement and reduced to less than 60% over time for counties with high percentage floodplain area. Flood events, structural and non-structural protection measures influenced floodplain population dynamics over time and learning effect, i.e. social memory of flood found was seven years. At the county level- Sebastian county, Arkansas, the proportion of floodplain population varies significantly with a variance of 0.04 and a standard deviation of 0.19. The ratio of floodplain population in Sebastian was 29% in 1820, which increased and decreased over the years and about 70% in 2010. In addition to flood events, different intervention measures, the floodplain population dynamics in the Sebastian county are influenced by the social, economic and political phenomenon, examining which is out of the scope of this study. The learning effect of flood seems to be eight years in the case of Sebastian county. The population dynamics influenced by a different social, geographical, economic, political and hydrological phenomenon which makes it a complicated system to comprehend within the present scope of the study. The result shows that the floodplain population dynamics can vary for different geographical scale. Therefore, the geographic extent should also need to consider while using population dynamics in flood disaster management and mitigation strategy development, policy formulation and implementation. / Flodslätter är viktiga platser för samhällets ekonomiska samt sociala utveckling och har varit det sedan är lång tid tillbaka, även om de från och till har drabbats av olika katastrofer såsom översvämning och erosion. Översvämning är en av de största naturliga katastrofer som sker i USA. Ungefär 10 % av befolkningen bor i 100- och 500-års flodslätter som emellertid förändras på grund av olika anledningar, inklusive översvämningar. I denna studie undersöks den tillfälliga relationen mellan översvämning, relaterad skada, olika ingripande åtgärder och fattigdomsnivå med en befolkningsdynamik i flodslättsområden. Vidare sker denna undersökning i tre olika nivåer – nationellt: USA som ett helt land, stats-nivå: Arkansas och län: Sebastian County, Arkansas där de olika dynamikerna i de tre nivåerna jämförs. På den nationella nivån utvärderades befolkningsdynamiken med avseende på flodslätten till den totala populationen och befolkningstillväxt. Resultatet visar att befolkningsdynamiken förändras beroende på om den betraktas ur ett nationellt, statligt eller läns perspektiv. Ur ett nationellt perspektiv flyttar flodslättsbefolkningar till olika områden med tiden. Ur ett statligt perspektiv är flodslättsbefolkningar känsliga mot översvämningar, skada och olika ingripande åtgärder. På länsnivå, utöver översvämningsrelaterade variabler, är flodslättsbefolkningar känsliga mot andra socio-ekonomiska faktorer som inte behöver vara relaterade till översvämningar. Resultatet indikerar således att översvämningar inte alltid behöver vara den faktorn som styr befolkningsdynamiken i flodslättsområden på den lokala nivån samt beslutet att flytta till en flodslätt påverkas av olika socio- ekonomiska faktorer, inklusive översvämning. På den nationella nivån kan däremot både påverkan av översvämningar och relaterade variabler på befolkningsdynamiken i flodslättsområden observeras.

MSc (Statistics) / Department of Statistics / Haulage trucks and cross border traders cross through Beitbridge border post from landlocked countries such as Zimbabwe and Zambia for the sake of trading. Because of global warming, South Africa has lately been experiencing extreme weather patterns in the form of very high temperatures and heavy rainfall. Evidently, in 2013 tra c could not cross the Limpopo River because water was owing above the bridge. For planning, its important to predict the likelihood of such events occurring in future. Extreme value models o er one way in which this can be achieved. This study identi es suitable distributions to model the annual maximum heights of Limpopo river at Beitbridge border post. Maximum likelihood method and the Bayesian approach are used for parameter estimation. The r -largest order statistics was also used in this dissertation. For goodness of t, the probability and quantile- quantile plots are used. Finally return levels are calculated from these distributions. The dissertation has revealed that the 100 year return level is 6.759 metres using the maximum likelihood and Bayesian approaches to estimate parameters. Empirical results show that the Fr echet class of distributions ts well the ood heights data at Beitbridge border post. The dissertation contributes positively by informing stakeholders about the socio- economic impacts that are brought by extreme flood heights for Limpopo river at Beitbridge border post

Natural hazards cause enormous amounts of damage worldwide every year. Since 1994 more than 1.35 billion people have lost their lives and more than 116 million homes have been damaged. Understanding of disaster risk implies knowledge about vulnerability, capacity, exposure of persons and assets, hazard characteristics and the environment. Quantitative damage assessments are a fundamental part of disaster risk management. There are, however, substantial challenges when quantifying damage which depends on the diversity of hazards and the fact that one hazardous event can negatively impact a society in multiple ways. The overall aim of the thesis is to analyze the relationship between climate-related natural hazards and subsequent damage for the purpose of improving the prerequisite for quantitative risk assessments in the future. The thesis concentrates on two specific types of consequences due to two types of hazards, 1) damage to buildings caused by lake floods, and 2) loss of lives caused by quick clay landslides.  Several causal relationships were established between risk factors and the extent of damages. Lake water levels increased the probability of structural building damage. Private damage reducing measures decreased the probability of structural building damage. Extent of damage decreased with distance to waterfront but increased with longer flood duration while prewar houses suffered lower flood damage compared to others. Concerning landslides, the number of fatalities increased when the number of humans in the exposed population increased. The main challenges to further damage estimation are data scarcity, insufficient detail level and the fact that the data are rarely systematically collected for scientific purposes. More efforts are needed to create structured, homogeneous and detailed damage databases with corresponding risk factors in order to further develop quantitative damage assessment of natural hazards in a Nordic perspective. / Naturolyckor orsakar enorma mängder skador över hela världen varje år. Under åren 1994-2013 förlorade mer än 1,35 miljoner människor sina liv och mer än 116 miljoner hem skadades. Förståelse av risk för naturolyckor innebär kunskap om sårbarhet, kapacitet, exponering av personer och tillgångar, hot och miljö. Kvantitativa skadebedömningar, som är en viktig del av riskbedömningar, omfattas av stora utmaningar som grundar sig i hotens mångfaldighet och det faktum att en naturolycka kan påverka ett samhälle negativt på många olika sätt. Det övergripande syftet med avhandlingen är att analysera förhållandet mellan naturkatastrofer och potentiellt påföljande skador i syfte att förbättra förutsättningarna för kvantitativa riskbedömningar i framtiden. Avhandlingen koncentrerar sig på två typer av naturolyckor med specifika konsekvenser, 1) skador på byggnader till följd av sjö-översvämningar, och 2) förlust av liv orsakat av lerskred. Flera orsakssamband mellan riskfaktorer och omfattning av skador har identifierats. Sjöarnas vattennivåer ökade sannolikheten att drabbas av strukturell byggnadsskada, samtidigt som privat initierade åtgärder minskande sannolikheten.. När avstånd mellan sjö och byggnad ökade minskade omfattningen av översvämningsskador, men ökade ju längre sjööversvämningen varade. Hus byggda före 1940 fick mindre skador jämfört med andra hus. Andelen dödsfall i samband med skred i kvicklera ökade när antal människor i den exponerade befolkningen ökade. Den största utmaningen i att förbättra dagens kvantitativa skadebedömningar är den rådande databristen vad gäller förluster och tillhörande riskfaktorer. Denna brist beror på otillgänglig skadedata, bristande detaljnivå på skadedata och tillhörande risk faktorer, och att uppgifterna sällan samlas systematiskt i syfte att studera kausalitet. / The overall aim of the thesis is to analyze the relationship between climate-related natural hazards and subsequent damage for the purpose of improving the prerequisite for quantitative risk assessments in the future. The thesis concentrates on two specific types of hazards with specific types of consequences, 1) damage to buildings caused by lake floods, and 2) loss of lives caused by quick clay landslides.  Several causal relationships were established between risk factors and the extent of damages. Lake water levels increased the probability of structural building damage. Private damage reducing measures decreased the probability of structural building damage. Extent of damage decreased with distance to waterfront but increased with longer flood duration while prewar houses suffered lower flood damage compared to others. Concerning landslides, the number of fatalities increased when the number of humans in the exposed population increased. The main challenges to further damage estimation are data scarcity, insufficient detail level and the fact that the data are rarely systematically collected for scientific purposes.

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.

In den 10 Jahren, die seit dem Extremhochwasser in Sachsen vergangen sind, wurde viel für den Hochwasserschutz getan: die Vorhersage, die Kommunikation sowie die Hochwasserschutzanlagen wurden verbessert und es wurden neue Deiche sowie Hochwasserrückhaltebecken errichtet oder angepasst. Eine wichtige Frage ist aber, wie sich das Hochwasserbewusstsein der potenziell betroffenen Bevölkerung entwickelt hat. Im Beitrag wird der Frage nachgegangen, ob die Lehren von 2002 in Erinnerung sind und weitergegeben wurden oder ob das Hochwasserbewusstsein nachgelassen hat und man sich angesichts besseren Schutzes in Sicherheit wiegt.