Coastal management accounting for shoreline erosion and coastal flooding requires information about various physical processes that take place over a range of temporal and spatial scales. Field measurements provide information on the past and current coastal environment and statistical tools are used to determine extreme conditions that can lead to damage. However, in a changing climate, these conditions cease to be statistically stationary, making predictions problematic. To assess future conditions, a set of scenarios for greenhouse gas emissions has been defined to project impacts on global oceanographic conditions and sea level rise. This thesis estimates the effect of these global projections on coastal processes off the North Norfolk coast of the UK. A model system is set up to downscale global conditions on to nearshore conditions (wave climate, water level and beach profile), which influence coastal stability and coastal flood risk. The system is based on coupling numerical models for different temporal and spatial scales. The area contains large tidal sandbanks and shore-connected sand ridges. The downscaling procedure accounts for interactions that take place on the upper part of the continental shelf where these large-scale seabed features affect wave propagation, tidal flows and sediment transport. The modelling system is then validated against historical data and then used to compute long-term inshore hydrodynamic characteristics and sediment transport resulting from future projections of climate change and sea level rise. This enables an assessment of extreme inshore wave heights, overtopping discharge rates and their occurrence at a sea defence through extreme joint probability analysis. This modelling assumes a fixed seabed. However, the system includes a sub model for the release of sediment from the cliff erosion, which provides a source of sediment for the maintenance of the offshore sandbanks. The link between the cliff and the sandbanks is demonstrated by computing the residual sediment transport. The model system is also used to assess the impact of offshore sand extraction on coastline erosion. Finally, the system is used to analyse an overtopping and flood inundation event at Walcott in 2007 enabling uncertainties in the predictions to be assessed.

The model choice problem in Hydrology is illustrated by means of the optimum levee design for flat rivers along a confluence reach. Special attention is given to the selection of a probability distribution for the joint flood stages. The optimality criterion used is the minimization of construction plus expected flood damage costs. The main assumption in the mathematical model is that the levee profile is uniquely determined as a function of the levee heights at the extremes of the reach; thus the problem is reduced to the determination of the optimum pair of extreme levee heights. The selection of a probability distribution of flood stages, from a set of distributions estimated from the partial duration series, is performed using either one of two selection procedures: likelihood of the Chi -square statistic and sample likelihoods. A composite distribution, taking into account the model uncertainty, is also derived. The methodology presented is applied to the remodeling of the levee on the west bank of the Zagyva River, in Hungary. A sensitivity analysis is performed, using the best ranking distributions according to the two model choice procedures. The composite distribution appears to offer a reasonable choice.

Flash flooding, as a result of excessive rainfall in a short period, is considered as one of the worst environmental hazards in arid regions. Areas located in the western provinces of Saudi Arabia have experienced catastrophic floods. Geomorphologic evaluation of hydrographic basins provides necessary information to define basins with flood hazard potential in arid regions, especially where long-term field observations are scarce and limited. Six large basins (from North to South: Yanbu, Rabigh, Khulais, El-Qunfza, Baish and Jizan) were selected for this study because they have large surface areas and they encompass high capacity dams at their downstream areas. Geographic Information System (GIS) and remote sensing techniques were applied to conduct detailed morphometric analysis of these basins. The six basins were further divided into 203 sub-basins based on their drainage density. The morphometric parameters of the six basins and their associated 203 sub-basins were calculated to estimate the degree of flood hazard by combining normalized values of these parameters. Thus, potential flood hazard maps were produced from the estimated hazard degree. Furthermore, peak runoff discharge of the six basins and sub-basins were estimated using the Snyder Unit Hydrograph and three empirical models (Nouh’s model, Farquharson’s model and Al-Subai’s model) developed for Saudi Arabia. Additionally, recommendations for flood mitigation plans and water management schemes along these basins were further discussed.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23173号 / 工博第4817号 / 新制||工||1753(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 堀 智晴, 教授 田中 茂信, 教授 角 哲也 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The Santa Ynez Mountains of Santa Barbara County, California, have seen many major storm events during the past century. San Jose Creek, which runs out of these mountains, through the town of Goleta, and into the Pacific Ocean, has experienced several intense flood events as a result. The lower portion of the creek was diverted in 1960 to alleviate flooding through Old Town Goleta. However, flooding still occurred in the storms of 1995 and 1998. This study incorporates a hydraulic analysis component of a project aimed at re-designing this diverted portion of the channel. It presents an analysis of modifications to this reach in order to improve its capacity and reduce flooding during a 100-year event. As one of the most prominent software for hydraulic modeling for steady and unsteady state open channel flow, HEC-RAS is used to analyze multiple variations in channel geometry and combinations of lining materials. Of these modifications, the best configuration is suggested.

CASCADE 2001 is a multi-basin flood routing program used in areas of flat terrain. CASCADE was used for different situational elements including the Florida Keys, Broward County, and Pensacola. The goal for this screening tool was to create flood inundation watershed mapping for the Florida Division of Emergency Management (FDEM). After showing the risks of flooding that could occur in Florida, the thought of how useful CASCADE can be in other environmental conditions. The Rocky Mountains were selected to show the effect of flood inundation that can be mirrored in an opposite condition from prior experimentation. We chose to test this program in an area with mountainous terrain like the region of Grand Lake, Colorado. Rainfall, in collaboration with groundwater tables, ground soil storage and topography have the most effect on the CASCADE modeling program. Effects that were not used in the Florida models but added for Grand Lake included snowmelt. Snowmelt in the Rocky Mountains affects the flow of the Colorado River causing excess discharge that flows throughout the valleys and into Shadow Mountain Lake. WINSRM was a recommended model that could be used to simulate snowmelt during different months of Colorado’s spring season. The effects of snowmelt and rainfall flooding can be compared in relation to each other. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Probabilistic risk assessment (PRA) has been used in various engineering and technological fields to assist regulatory agencies, and decision-makers to assess and reduce the risks inherent in complex systems. PRA allows decision-makers to make risk-informed choices rather than simply relying on traditional deterministic flood analyses (e.g., a Probable Maximum Flood) and therefore supports good engineering design practice. Type and quantity of available data is often a key factor in PRA at an early stage for determining the best methodology. However, implementation of PRA becomes difficult and challenging since probability distributions need to be derived to describe the variable states. Flood protection is one of the rare fields in civil engineering where probability is extensively used to describe uncertainty and where the concept of failure risk is explicitly part of the design. The concept of return period is taught in all civil engineering classes throughout the world, and most cities in the developed world have developed flood risk maps where the limits of the 50-year or 100-year flood are shown. While this approach is useful, it has several limitations: • It is based on a single flow value while all flow ranges contribute to the risk; • It is not linked to the actual economic damage of floods; • So far, flood risk maps only account for river water levels. It has been demonstrated that intense rainfall causes significant property damages in West Africa. This study aimed to explore the possibility of developing and implementing a probabilistic flood risk estimation framework where all flow ranges are accounted for: 1) The probability of flood occurrence and the probabilistic distribution of hydraulic parameters, and 2) The probability of damages are spatially calculated in order for the decision-makers to take optimal adaptation decisions (e.g., flood protection dike design, recommendations for new buildings, etc.). In this study the challenges of inferring the probability distribution of different physical flood parameters in a context of sparse data, of linking their parameters to flood damages, and finally the translation of the estimation risk into decision were explored. The effect of the choice of the one-dimensional (1-D) or two-dimensional (2-D) hydraulic models on the estimated flood risk and ultimately on the adaptation decisions was investigated. A first case study on the city of Niamey (Niger, West Africa), was performed using readily available data and 1-D and 2-D HEC-RAS (Hydrologic Engineering Center-River Analysis System) models. Adaptation options to flood risk in Niamey area were examined by looking at two main variables: a) Buildings’ material (CAS: Informal constructions – a mixture of sundried clay and straw, also known as Banco, BAN: Mud walls, DUR: Concrete walls, and SDU: Mud walls covered by mortar); and b) Dike height within a scenario-based framework, where numerical modelling was undertaken to quantify the inundated area. The 1-D and 2-D hydraulic models, HEC-RAS, were tested on a 160 km reach of the Niger River. Using the numerical modelling, water levels within the inundated areas have been identified. The extent of residential areas as well as exposed assets (polygons and building material) associated with each scenario have been evaluated. 1000 probabilistic flood maps were generated and considered in the estimation of the total loss. Benefits and costs of different adaptation options were then compared for residential land-use class in order to implement flood risk maps in the city of Niamey. Results show the individual as well as the combined impact of the two abovementioned variables in flood risk estimation in Niamey region. Dike heights ranged from 180.5 m to 184 m, at a 0.5 m interval, and buildings’ material were considered to be of 0% to 100% of each type, respectively. The results enable decision-makers as well as the regulators to have a quantitative tool for choosing the best preventive measures to alleviate the adverse impacts arising from flood. Also, because of the lack of detailed information on the exposed infrastructure elements in the study area, a feasible yet fast and precise method of extracting buildings from high-resolution aerial images was investigated using an Artificial Intelligence (AI) method – Deep Learning (DL). The applied deep learning method showed promising results with high accuracy rate for the area of interest in this study and was able to successfully identify two introduced classes of Building and Background (non-building). The findings contend that although the proposed structural adaptation options, as a resisting to environment approach, are applied to the area of interest and considered to be technically feasible, other non-structural measures, which have long-term effect of risk mitigation, should be taken into consideration, especially for highly hazard-prone areas. The results of this study would significantly help in loss estimation to the buildings due to the yearly floods in the region of interest, Niamey, Niger. However, since the buildings are of various type of material, having an accurate building database has a great importance in assessing the expected level of damage in the inundated areas, especially to the critical buildings (hospitals, schools, research labs, etc.) in the area.

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The aim of this Master's thesis is to design and to implement the security test in considering a resistance of the device under test to the effects of the distributed denial of service attack DDoS SYN Flood. After processing the test results is developed a protocol about security test of the device under test. In this thesis are tested two devices, namely CISCO ASA5510 firewall and a server with the specified name Server. The theoretical part of the thesis discusses the primary types of network attacks such as reconnaissance, gain access and denial of service attacks. Explained the concept of DoS and its principle, further types of DoS attacks and distributed denial of service attacks DDoS.

This work deals with the security of computer networks based on TCP/IP protocol stack. The main objective is to develop a generator of DoS flooding attacks which carries out attacks such SYN flood, RST flood, UDP flood, ICMP flood, ARP flood, DNS flood and DHCP starvation. The theoretical part describes the features of the mentioned attacks and protocols or mechanisms associated with them. Next part deals with the comparison of selected tools (Hping3, Mausezahn, Trafgen) in terms of number of packets per second (pps) and the link utilization (MB/s). The practical part describes design and implementation of the new attacking tool. There is explained the importance of it’s individual modules, it’s installation and usage options. New tool is also being tested. Then there is described the development, options and installation of control interface which is in the form of web application.