Yes / Urban flooding is a combined product of the climate and watershed geomorphology. River system is one of the vital components of watershed geomorphology. The geomorphic characteristics of rivers have important effect on the formation of flooding. However, there have been few attempts so far to investigate the relationship between flooding frequency, the probability of flooding, and the geomorphological complexity of river system. Such relationship is essential in order to predict likely responses of flooding frequency to the large-scale changes in the complexity of the river networks induced by accelerating urbanization around river. In this study we investigate the correlation between geomorphological characteristics of river system and the probability of flooding. Hangzhou city in China, which has suffered severe flooding, is chosen as a case study to evaluate this correlation and to investigate the impact of changes of drainage networks morphology on the local flooding. The fractal dimension, which is used to quantitatively assess geomorphological complexity of river network, is calculated by using box-counting method based on fractal geometry for eight sub river networks in Hangzhou. A model based on the correlation of flooding frequency and fractal dimension is established. The model is applied to investigate the effect of the rapid urbanization induced changes of river geomorphology on the local flood frequency in two typical regions in Hangzhou. The results show that the flood frequency/events increases with the decrease of fractal dimension of the river network, indicating that the geomorphologic complexity of river network has an important effect on flooding. This research has great referential value for future flood quantitative investigation and provides new method for urban flood control and river system protection. / Key Scientific and Technical Project of Water Conservancy of Zhejiang Province (Grant No: RB1401)

Urban flood models are an important tool in designing and analyzing municipalities sewer drainage systems and predicting the effect of potential extent and depth of future floods. In urban areas, coupled 1D-2D flood models are particularly useful as they can represent the surface- and sewer system and their interactions. But it iss common practice to simplify the sewer system by only simulating water exchange between both systems at manholes while neglecting the effect of grate inlets. To investigate the effect grate inlet representations have in flood models, the simulation results of different models created in the software MIKE FLOOD with the number of nodes and inlet sizes adjusted according to the location of actual grate inlets were compared. In addition, a comparison between the flood modeling softwares MIKE FLOOD and FLO-2D was performed, based on a case study in Motala.. It was found that both MIKE FLOOD and FLO-2D can predict similar flood propagation and maximum water depths. The MIKE FLOOD models predicted larger amounts of drained water via the sewer system. This was likely caused by the extra water added through water level correction in the MIKE FLOOD models combined with numerical instabilities in the FLO-2D sewer models. Adjusting the number and dimensions of nodes according to actual grate inlets proved to have little effect on the predicted maximum surface water depths. But it did result in decreased drainage capacity together with less sewer inflow compared to the models neglecting grate inlets. The inlet representation did have a significant effect on predicted flood durations, with the models neglecting grate inlets having shorter flood durations in downstream areas and longer flood durations in upstream areas compared to the other models. It was also found that that the effect inlet node representations has on flood durations heavily depends on their locations with nodes located in water gathering areas such as depressions with ponding water having the most effect.

Natural disasters like flooding have always been a big problem for countries around the world, but as the global climate changes and the number of people living in cities keeps growing, the threat of flooding has become a lot worse. Even though many studies have been conducted on flood mapping and vulnerability assessment in urban areas, this research addresses a significant knowledge gap in this domain. First, we used a flood depth estimation approach has been used to address the overestimation of urban flood mapping areas using Sentinel-1 images. Ten different combinations of the two initial VH and VV polarizations were used to rapidly and accurately map urban floods within open-source Google Earth Engine platforms using four different methods. The inclusion of flood depth has improved the accuracy of these methods by 7% on average. Next, we focused our research to find out who is most at risk in the floodplain areas. Minority communities, such as African Americans, as a result of socioeconomic constraints, face more difficulties. So, next we conducted an analysis of spatial and temporal changes of demographic patterns (Race) in five southern cities in US. From our analysis we have found that in majority of cities, the minority population within the floodplain has increased over the past two decades, with the exception of Charleston, South Carolina, where the white population has increased while the minority population has decreased. Building upon these insights, we have included more socio-economic and demographic variables in our analysis to find out the more holistic view of the vulnerable people in two of these cities (Jackson and Birmingham). Due to high autocorrelation between explanatory variables, we used Principal Component Analysis (PCA) along with global and local regression techniques to find out how much these variables can explain the vulnerability. According to our findings, the spatial components play a significant role in explaining vulnerabilities in greater detail. The findings of this research can serve as an important resource for policymakers, urban planners, and emergency response agencies to make informed decisions in future events and enhancing overall resilience.

As respostas das cidades aos impactos provocados pela força das águas demonstram a inépcia de grande parte dos lugares em lidar com esse fenômeno natural. O número crescente de prejuízos causados pela incapacidade de enfrentar as inundações é um dos maiores desafios enfrentados pelo homem na atualidade. Joinville, a maior cidade do estado de Santa Catarina/Brasil, tem enfrentado esse desafio desde sua fundação sem conseguir responder de modo positivo à força da água. Desde o primeiro registro de inundação na Bacia do Rio Cachoeira, em 1865, a ocorrência desse evento manteve certa regularidade, intensificada de modo significativo no início do século XXI. Nesse contexto, supôs-se que os seus rios não tenham sido considerados elemento urbano no processo de desenvolvimento da cidade. Assim, a verificação desse pressuposto consiste o principal objetivo desta pesquisa. Para atingir esse objetivo foram estabelecidos outros dois objetivos específicos: o primeiro propôs identificar na História os diferentes tipos de comportamento decorrentes da relação estabelecida entre o homem (e suas cidades) e as águas. A revisão bibliográfica permitiu a classificação de três tipos básicos de relação quando a cidade percebe as águas como obstáculo, quando as vê como ameaça e quando as percebe como vantagem, sendo esta última de maior interesse de estudo que foi aprofundado através da análise da história da região de Bolonha, Itália. O segundo objetivo específico foi identificar as estratégias adotadas que asseguraram uma condição de estabilidade diante da força e imprevisibilidade das águas. Foram identificadas quatro estratégias que, juntas, determinam o comportamento dos lugares que consideram as águas como elemento urbano. Para atingir o objetivo principal desta pesquisa, verificou-se se as decisões tomadas por Joinville seguiram em sentido favorável ou contrário à direção de cada uma das quatro estratégias. A estrutura de pesquisa foi baseada no Método do Planejamento Estratégico e utilizou o embasamento analítico fornecido pela Teoria do Espaço Geográfico, de Milton Santos. O trabalho de investigação partiu de dados extraídos de fontes primárias e secundárias e o arcabouço construído definiu os preceitos que permitiram corroborar a hipótese da pesquisa, levando a afirmar que o rio não foi considerado elemento urbano no processo de desenvolvimento da cidade de Joinville. Os estudos realizados evidenciam que as quatro estratégias identificadas são componentes fundamentais do processo de planejamento para a construção de cidades mais resilientes e seguras diante dos fenômenos das inundações urbanas. / The responses of the cities to the impacts caused by the force of the waters demonstrate the ineptitude of most places to deal with this natural phenomenon. The increasing number of losses caused by the inability to face the flooding is one of the biggest challenges of our society today. Joinville, the largest city in the state of Santa Catarina/Brazil, has faced this challenge since its founding and has been unable to respond positively to the force of the water. Since the first recorded flood in the Cachoeira River Basin in 1865, the occurrence of this event has some regularity but has increased significantly in the early twenty-first century. In this context, this research has assumed that Joinville\'s rivers have not been considered urban element in the development process of the city. Thus, the verification of this assumption consisted in the main objective of this research. To achieve this objective, more two specific targets were set: the first one was to identify in the History the different types of behavior resulted from the relationship between man (and their cities) and water. The literature review allowed the classification of three basic types of relationship - when the city realizes the waters as a barrier, when it sees the waters as a threat and when it realizes them as an advantage, the latter was the focus of this study that was deepened by examining the history of the region of Bologna, Italy. The second specific objective was identifying the strategies adopted which ensured a stability condition against the strength and unpredictability of water. This study has identified four strategies that together determine the behavior of the places that regard water as an urban element. To achieve the main goal of this research, it was analysed if the decisions taken by Joinville followed in favorable or contrary sense of each of the four identified strategies. The research structure was based on the Method of Strategic Planning and used the analytic basis provided by the Geographic Theory of The Space formulated by Milton Santos. This research work used data extracted from primary and secondary sources, and the constructed outline has defined the precepts that have allowed to corroborate the hypothesis of the research, leading to state that the rivers were not considered urban element in the development process of the city of Joinville. The studies showed that the four strategies identified are key components for the planning process to build more resilient and safer cities against the phenomena of urban flooding.

Global warming and climate change is believed to increase the hydro-meteorological natural disasters. Floods, the most widespread of natural hazards, are expected to occur more frequently and severely in the near future. This means that urban areas of Turkey are likely to be under intensive threat of floods, the adverse impacts of which are already considered only next to that of earthquakes. The recent disaster policy of United Nations together with contemporary interpretations of risk society shifted to capacity building and risk management prior to hazards, rather than preparations for relief after disasters. This historical turn in policy demands a more comprehensive and integrated form of planning for the mitigation of risks in the riverain cities of Turkey than existing approaches. Turkey&amp / #8217 / s current flood protection structure seems to be based on the surveys and assessments of a central authority and on its limited powers of intervention. The local municipal administrations are under different interests and pressures for development and land-use. It seems essential to integrate flood risk mitigation efforts with the local planning system and to involve municipalities in their estimations of risks and its declaration on official duty, as contemporary international approaches indicate. This conviction is based on a sample survey of four cases of riverine cities in Turkey, and on a review of current approaches in a sample of international cases. Findings on four riverain case cities indicate that river floods turn into destructive disasters mainly due to tolerant land-use decisions. Inaccurate and discrete implementations and developments in and through the river basins are a second source of flood losses. Currently, neither urban development plans nor available flood plans are equipped with necessary measures to mitigate risks. Findings indicate that current vulnerabilities are greater in value than investments made to curb flood risks. Independent and discrete efforts of mitigation seem to generate illusory feelings of safety, which aggravates vulnerabilities. The compulsory declaration of flood vulnerabilities by municipalities themselves in their entitlement for special subsidies could raise the general level of awareness, could curb further vulnerabilities, and contribute to the articulation of planning methods in the more effective mitigation control.

Les inondations représentent le premier danger naturel sur chaque continent, avec des préoccupations particulières centrées sur les inondations urbaines pour l'urbanisation sans précédent, qui augmente la vulnérabilité des sociétés humaines aux inondations. Pour les difficultés d'accès aux données en temps réel, la méthode numérique semble être une approche puissante pour la prévision des inondations et l'atténuation des dommages. Dans cette thèse, un nouveau logiciel Flood1D2D pour la modélisation des crues urbaines a été proposé en utilisant le maillage de couplage 1D2D, avec 1D dans la rue et 2D appliqué au carrefour. Le logiciel est conçu sur la base de l'installation située dans ICube Strasbourg et validée à l'aide de cas de tests synthétiques. La nouveauté du modèle est de rendre compte de l'effet de recirculation en utilisant la fonction de porosité, et de reproduire la convexité dans les profils de profondeur le long de la rue en aval de chaque carrefour où une zone de recirculation apparaît. Une analyse de sensibilité basée sur la variance est également réalisée pour les modèles classiques d'eau peu profonde 1D et 2D pour l'étalonnage de modèles et la collecte de données. / Flooding represents the first natural hazard on each continent, with special concerns are focused on urban flooding for the unprecedented urbanization, which increases the vulnerability of human societies to floods. For the accessing difficulties of real-time data, numerical method seems to be a powerful approach for flood forecasting and damage mitigation. In this thesis, a new software Flood1D2D for urban flood modeling has been proposed using 1D2D coupling mesh, with 1D on the street and 2D applied on the crossroad. The software is designed based on the rig located in ICube Strasbourg and validated using synthetic test cases. The novelty of the model is to account for the recirculation effect using porosity function, and it can reproduce the convexity in water depth profiles along the street downstream each crossroad where a recirculation zone appears, which can't be accounted using roughness only. Variance based sensitivity analysis is also performed for classical 1D and 2D shallow water models for model calibration and data collections.

As respostas das cidades aos impactos provocados pela força das águas demonstram a inépcia de grande parte dos lugares em lidar com esse fenômeno natural. O número crescente de prejuízos causados pela incapacidade de enfrentar as inundações é um dos maiores desafios enfrentados pelo homem na atualidade. Joinville, a maior cidade do estado de Santa Catarina/Brasil, tem enfrentado esse desafio desde sua fundação sem conseguir responder de modo positivo à força da água. Desde o primeiro registro de inundação na Bacia do Rio Cachoeira, em 1865, a ocorrência desse evento manteve certa regularidade, intensificada de modo significativo no início do século XXI. Nesse contexto, supôs-se que os seus rios não tenham sido considerados elemento urbano no processo de desenvolvimento da cidade. Assim, a verificação desse pressuposto consiste o principal objetivo desta pesquisa. Para atingir esse objetivo foram estabelecidos outros dois objetivos específicos: o primeiro propôs identificar na História os diferentes tipos de comportamento decorrentes da relação estabelecida entre o homem (e suas cidades) e as águas. A revisão bibliográfica permitiu a classificação de três tipos básicos de relação quando a cidade percebe as águas como obstáculo, quando as vê como ameaça e quando as percebe como vantagem, sendo esta última de maior interesse de estudo que foi aprofundado através da análise da história da região de Bolonha, Itália. O segundo objetivo específico foi identificar as estratégias adotadas que asseguraram uma condição de estabilidade diante da força e imprevisibilidade das águas. Foram identificadas quatro estratégias que, juntas, determinam o comportamento dos lugares que consideram as águas como elemento urbano. Para atingir o objetivo principal desta pesquisa, verificou-se se as decisões tomadas por Joinville seguiram em sentido favorável ou contrário à direção de cada uma das quatro estratégias. A estrutura de pesquisa foi baseada no Método do Planejamento Estratégico e utilizou o embasamento analítico fornecido pela Teoria do Espaço Geográfico, de Milton Santos. O trabalho de investigação partiu de dados extraídos de fontes primárias e secundárias e o arcabouço construído definiu os preceitos que permitiram corroborar a hipótese da pesquisa, levando a afirmar que o rio não foi considerado elemento urbano no processo de desenvolvimento da cidade de Joinville. Os estudos realizados evidenciam que as quatro estratégias identificadas são componentes fundamentais do processo de planejamento para a construção de cidades mais resilientes e seguras diante dos fenômenos das inundações urbanas. / The responses of the cities to the impacts caused by the force of the waters demonstrate the ineptitude of most places to deal with this natural phenomenon. The increasing number of losses caused by the inability to face the flooding is one of the biggest challenges of our society today. Joinville, the largest city in the state of Santa Catarina/Brazil, has faced this challenge since its founding and has been unable to respond positively to the force of the water. Since the first recorded flood in the Cachoeira River Basin in 1865, the occurrence of this event has some regularity but has increased significantly in the early twenty-first century. In this context, this research has assumed that Joinville\'s rivers have not been considered urban element in the development process of the city. Thus, the verification of this assumption consisted in the main objective of this research. To achieve this objective, more two specific targets were set: the first one was to identify in the History the different types of behavior resulted from the relationship between man (and their cities) and water. The literature review allowed the classification of three basic types of relationship - when the city realizes the waters as a barrier, when it sees the waters as a threat and when it realizes them as an advantage, the latter was the focus of this study that was deepened by examining the history of the region of Bologna, Italy. The second specific objective was identifying the strategies adopted which ensured a stability condition against the strength and unpredictability of water. This study has identified four strategies that together determine the behavior of the places that regard water as an urban element. To achieve the main goal of this research, it was analysed if the decisions taken by Joinville followed in favorable or contrary sense of each of the four identified strategies. The research structure was based on the Method of Strategic Planning and used the analytic basis provided by the Geographic Theory of The Space formulated by Milton Santos. This research work used data extracted from primary and secondary sources, and the constructed outline has defined the precepts that have allowed to corroborate the hypothesis of the research, leading to state that the rivers were not considered urban element in the development process of the city of Joinville. The studies showed that the four strategies identified are key components for the planning process to build more resilient and safer cities against the phenomena of urban flooding.

Le but de cette thèse est d'étudier la modélisation détaillée des écoulements qui ont lieu lors des inondations urbaines. Dans une première partie, des écoulements en bifurcation incluant des petits obstacles génériques ou des profils de canaux avec trottoirs sont étudiés sur une maquette expérimentale, puis simulés numériquement avec le modèle bidimensionnel Rubar20. Les résultats expérimentaux et numériques montrent l'avantage d'inclure des obstacles de petite taille dans un modèle d'inondation urbaine, alors qu'il n'y a qu'un intérêt limité à utiliser une topographie détaillée des rues. Dans une deuxième partie, les interactions entre écoulements de surface et écoulements en conduites souterraines sont étudiées. Un modèle physique de système de drainage urbain permet de valider un modèle analytique prédisant les débits d'échange entre les deux couches d'écoulement. Une modélisation 1D/2D (conduite/rue) est mise en place avec les modèles Rubar3/Rubar20 et validée sur des écoulements expérimentaux observés sur le modèle physique. Dans une troisième partie, les inondations dans la ville d'Oullins (près de Lyon, France) sont étudiées. La modélisation des écoulements de surface est validée avec des données de terrain, et nous discutons l'intérêt de plusieurs représentations du milieu urbain. L'intégration du réseau d'assainissement dans un modèle 1D/2D reste affectée par plusieurs incertitudes, mais cette étape montre l'intérêt de la modélisation couplée pour décrire les interactions complexes des écoulements lors d'inondations urbaines, ainsi que les limites de l'approche développée pour les écoulements à faible profondeur / Aim of this thesis is to study the detailed modelling of flows that occur during urban floods. In a first part, bifurcation flows including small obstacles or channel profiles with sidewalks are studied on an experimental facility, and then numerically simulated with the two dimensional model Rubar20. Experimental and numerical results show the benefits of including small obstacles in an urban flood model, whereas there is only little benefit of using a detailed representation of the streets topography. In a second part, interactions between surface and underground pipe flows are studied. A physical model of an urban drainage system allows the validation of an analytical model predicting exchange discharges between both flow layers. A 1D/2D modelling (pipe/street) is set up with the models Rubar3/Rubar20 and validated on experimental flows observed on the physical model. In a third part, floods in the city of Oullins (near Lyon, France) are studied. Surface flows modelling is validated with field data, and we discuss the interest of several representations of the urban area. Integration of the sewer system in a 1D/2D model remains impacted by several uncertainties, yet this step shows the interest of the coupled modelling to describe complex flows interactions during urban floods, as well as limitations of the developed approach for shallow flows

Flooding is an important concern for the UK, as evidenced by the many extreme flooding events in the last decade. Improved flood risk intervention strategies are therefore highly desirable. The application of hydroinformatics tools, and optimisation algorithms in particular, which could provide guidance towards improved intervention strategies, is hindered by the necessity of performing flood modelling in the process of evaluating solutions. Flood modelling is a computationally demanding task; reducing its impact upon the optimisation process would therefore be a significant achievement and of considerable benefit to this research area. In this thesis sophisticated multi-objective optimisation algorithms have been utilised in combination with cutting-edge flood-risk assessment models to identify least-cost and most-benefit flood risk interventions that can be made on a drainage network. Software analysis and optimisation has improved the flood risk model performance. Additionally, artificial neural networks used as feature detectors have been employed as part of a novel development of an optimisation algorithm. This has alleviated the computational time-demands caused by using extremely complex models. The results from testing indicate that the developed algorithm with feature detectors outperforms (given limited computational resources available) a base multi-objective genetic algorithm. It does so in terms of both dominated hypervolume and a modified convergence metric, at each iteration. This indicates both that a shorter run of the algorithm produces a more optimal result than a similar length run of a chosen base algorithm, and also that a full run to complete convergence takes fewer iterations (and therefore less time) with the new algorithm.

I Sverige inträffar många skyfall och intensiva regn under sommarmånaderna. Det finns inga uppenbara geografiska mönster, vilket är en skillnad gentemot älv- eller sjööversvämningar där det vanligtvis är känt vilka områden som kan komma att översvämmas vid en viss vattennivå eller ett visst vattenflöde. För individer och samhällsaktörer innebär en skyfallshändelse i många fall en stor överraskning då skyfall utvecklas snabbt och dagens meteorologiska prognossystem i stort inte lyckas att prognosticera extrema regn korrekt med avseende på mängd, tid och plats. Vädervarningar kommer med kort varsel eller uteblir helt. Konsekvenserna av intensiv nederbörd och skyfall är främst översvämningar och erosionsskador på byggnader och infrastruktur, men även störningar och avbrott i olika samhällsfunktioner som kan påverka samhället och individer utanför det drabbade området. I denna avhandling har 15 år av försäkringsskadedata använts för att undersöka samband mellan nederbördsintensitet och skyfallsskador. Även påverkan av andra faktorer som topografi, bebyggelse och socioekonomiska aspekter har undersökts. Resultaten visar att regnintensitet under ett 60 minuters intervall i kombination med korta perioder av extrem intensitet, tillsammans med topografiska faktorer spelar en betydande roll vid uppkomsten av skador.