Critical infrastructure networks (CIN) are essential systems that provide key socio-eco-nomical services. They can be classified into different sectors such as energy supply, in-formation and communication, water, food, health, transport, among others. Their pro-tection from hazards and constant improvements are crucial for ensuring the appropriate operation of a society and economy. In this context, the current study focused on analyzing the factors affecting the function-ing of one particular CIN in the water sector: the urban drainage networks (UDNs). More specifically, the present research focused on evaluating how does the structure of UDNs influence their function. Concepts and methods from complex network theory were used to evaluate structural properties of sewers systems and function was evaluated in terms wastewater flow quantitates and occurrence of node flooding and combined sewer over-flow (CSOs) events, considered as indicators if network performance. Initial results suggested that network metrics can be used as surrogate variables of UDNs main functions, i.e. transport and collection of wastewater. However, efficiency of this de-pended on the type of layout, i.e. physical arrangement of the network. Following studies focused then on developing a graph-theory based method to quantify the structure of an UDN and use it to evaluate the influence of layout on its function. Results suggested that sewer networks with a more meshed layout had a better performance, i.e. adverse events such as urban pluvial flooding and CSO discharges were less likely to occur, than UDNs with a branched layout. Furthermore, transitioning from a tree-like structure to a more meshed system was identified to be a cost-efficient measure for urban flooding manage-ment. It is concluded that the structure of an UDN, in terms of its layout, has a strong influence on its performance and therefore on its resilience. It is expected that the obtained results could serve as support for better management and operational actions of UDNs and could also serve as basis for the development of a new structural resiliency analysis based mainly on the UDN configuration.:1. General Introduction 2. Centrality and Shortest Path Length measures for the functional analysis of Urban Drainage Networks 3. Meshness of sewer networks and its implications for flooding occurrence 4. The Role of Sewer Network Structure on the Occurrence and Magnitude of Combined Sewer Overflows (CSOs) 5. Determination of Optimal Meshness of Sewer Network Based On a Cost-Benefit Analysis 6. Influence of Meshness on Urban Drainage Networks Resilience and its Implications 7. Conclusions and Outlook 8. Supplementary Information

One of the main challenges in promoting rainwater management into practise is the fact that it was not recognized as an interdisciplinary issue. We should seek ways how to open the problem to other professions, specially for architects and urban planners, who are the key element of its farther development. This work analyzes the reasons of this unsatisfactory state of rainwater management in the Czech Republic and it defines the possible ways how to remedy this state and outlines scenarios of its further development. The default document of the work is czech technical standard "TNV 75 9010 Hospodaření se srážkovými vodami". The new methodological guide, which is part of this work, is based on it. The work extends the range of measures which are mentioned in the standard. It brings new ways for assessing the benefits of the various measures to streamline the application of rainwater management measures in urban space.

A infiltração das águas de chuva dentro dos lotes urbanos é uma possível forma de promover o controle descentralizado do escoamento superficial na origem, com vistas ao gerenciamento das águas pluviais urbanas e conseqüente atenuação das cheias. Neste trabalho, foram conduzidos ensaios de campo com trincheiras de infiltração, em dois solos distintos, um arenoso e outro argiloso, com o objetivo de avaliar quantitativamente o comportamento hidráulico das estruturas de infiltração em resposta a volumes de escoamento. As trincheiras foram alimentadas com volumes de água controlados, e o campo de umidade do experimento foi monitorado com sonda de nêutrons, durante o processo de redistribuição da água no solo. Foi realizada a modelagem matemática do fenômeno bidimensional de infiltração em torno de trincheiras de seção retangular, em resposta à entrada de águas pluviais provenientes de áreas impermeabilizadas contíguas. A comparação entre os resultados experimentais e simulados pela equação bidimensional de Richards indica uma pequena defasagem dos valores de volume infiltrado e umidade do solo nos processos de infiltração e drenagem interna simulados em relação aos observados. A capacidade de infiltração da trincheira mostrou-se maior nos dados observados, possivelmente devido à simplificação de distribuição unimodal dos diâmetros dos poros adotada na modelagem numérica, uma vez que, experimentalmente, observou-se multimodalidade nos dois solos estudados. A curva de van Genuchten é, juntamente com a equação de Richards, a base do modelo computacional, e divergências no seu ajuste em relação aos dados observados podem conduzir a pequenas divergências dos volumes infiltrados e perfis de umidade ao longo do processo de infiltração simulado, em relação ao observado. São apresentadas algumas considerações de dimensionamento sobre a implantação de trincheiras de infiltração em lotes residenciais, bem como discussões com respeito aos planos diretores urbanos. É apresentado um estudo simplificado, baseado no método racional, sobre a redução no hidrograma de cheia proporcionada pelo uso de trincheiras em uma micro bacia urbana, o qual revelou reduções da ordem de até 94% do deflúvio superficial direto gerado pelo lote. / Stormwater infiltration process at the scale of housing is a possible way to promote the decentralized runoff control in order to manage the urban water and to attenuate flood peaks. In this work, field essays with infiltration devices at two different soils, either sandy and clay-loam soils, are assessed in order to study the hydraulic behavior of infiltration trenches to attenuate incoming runoff volume inputs. The infiltration trench experiments set a controlled water supply for specific boundary conditions, and the experimental moisture field were monitored with neutron probe during the water redistribution process at soil core. Bi-dimensional (2D) mathematical modeling is depicted at specific boundary conditions with a rectangular-trench layout, thereby mimicking a potential situation of runoff incoming from adjacent impervious areas. The comparison between experimental and numerical results, simulated by two-dimensional Richards\' equation, shows a small lag-time difference of both infiltrated volumes and soil moisture contents during infiltration and drainage periods. The trench infiltration capacity of observed data appears to be greater than simulated results, possibly due to an overall simplification of a uni-modal, homogeneous pore diameter distribution adopted by the modeling scheme. Experimental retention curves outline indirect evidences of multi-modal, heterogeneous behavior of pore structure. Bon van Genutchen-type retention curve and Richards-momentum equations represent the baseline approach to the computational model of non-saturated soils. Some fitting discrepancies between observed and simulated results could lead to negligible different estimations of infiltrated volumes and moisture profiles. Finally, further discussions on project design and best management practices (BMPs) of infiltration trenches at housing scale as well discussions on urban master plan are outlined herewith. A simplified study, based on rational method, is presented on the reduction of incoming hydrograph with the use of infiltration trenches. Preliminary results perform volume reductions of approximately 94% from incoming runoff generated at housing lots.

Este é um trabalho sobre as enchentes e as infraestruturas de drenagem na Região Metropolitana de São Paulo. Ele apresenta sua evolução histórica, na forma determinada pela submissão das diretrizes de drenagem aos interesses específicos no aproveitamento do potencial hidrelétrico das águas, na exploração capitalista do espaço de suas margens e na destinação de recursos de saneamento para a abertura de avenidas de fundo de vale. O trabalho observa que através deste processo a capacidade de escoamento das cheias na rede foi mantida em patamares abaixo do necessário, especialmente para atender vazões decorrentes do padrão de expansão da aglomeração, que resultaram em uma alta taxa de impermeabilização do solo e na paulatina ocupação das várzeas. O trabalho analisa a atuação do Estado e o desenvolvimento de diferentes programas de combate às inundações e planos de obra, focando a elaboração do Plano Diretor de Macrodrenagem, a partir de 1998. Então, é verificada a forma como os planos urbanísticos do município de São Paulo e das subprefeituras responderam às soluções propostas no plano de drenagem e os resultados obtidos até o momento com as obras de macrodrenagem. Conclui que a descontinuidade das soluções, a fragmentação das estâncias de planejamento e a ausência de uma unidade metropolitana de fato impedem que se estabeleçam soluções mais eficazes e, especialmente, que garantam a qualificação do espaço construído, levando em conta não apenas a demanda metropolitana pelo serviço prestado, mas também os aspectos sociais, econômicos e ambientais. / This paper focuses on floods and the drainage infrastructure in São Paulo Metropolitan Area. Firstly, it presents its evolution pointing out how economical interests in generating hydroeletric energy as well as in releasing new urban land prevailed over the initial drainage guidelines. It was also observed that confining streams within roads constrained its capacity to a low level to cope with growing peakflows demanded by the expansion of urban area which has led to increasing impervious surface rate. This was compounded by a gradual, but continuous, occupation of floodplains. State actions to deal with the above issues were analysed. Several flood control programs were developed leading to the 1998 Alto Tietê Watershed Macrodrainage Plan proposals. Then, these are studied in the light of how São Paulo\'s urban plans approached this subject, comparing their proposals with works built so far and the consequent outcomes. It is concluded that three main factors prevented that effective solution could come true: discontinuity of approaches, fragmentation of urban planning boards and lack of an actual metropolitan authority. Indeed, concerning drainage system, before these are overcome, many people still will long for urban improvement regarding social, economical and environmental aspects.

A primeira parte deste trabalho consistiu na instalação de pluviógrafos e linígrafos e levantamento de eventos hidrológicos com a obtenção de dados da distribuição espacial de precipitações observadas e hidrogramas resultantes. Experimentos de infiltração de água no solo foram realizados a partir de infiltrômetro de disco a fim de caracterizar a variabilidade espacial da condutividade hidráulica na bacia, obtendo-se dois conjuntos de dados que mostraram ser lognormalmente distribuídos com médias iguais a 15,8 mm/h e 5,47 mm/h. Estudo teórico foi conduzido na segunda parte do trabalho compreendendo o desenvolvimento de modelo hidrológico. A concepção do modelo parte da premissa de que toda a área da bacia possa ser representada por células derivadas de um modelo numérico de terreno (MNT), especificando-se em cada célula o equacionamento hidráulico-hidrológico. As heterogeneidades do solo e da precipitação foram estudadas através de simulação do modelo considerando-se distribuições espaciais diferentes para a condutividade hidráulica saturada e eventos de chuva. Os resultados mostraram que as diferenças entre as vazões de pico podem ser maiores que 100% , considerando-se graus de resolução máximo e mínimo quanto à precipitação, e reafirmaram o consenso de que o conhecimento da distribuição espacial da chuva é fundamental na calibração de modelos hidrológicos distribuídos. / In first part of this work consists on the installation of pluviographic, water-height graphs and surveying of hydrological events with obtained data from spatial distribution of precipitation observed and resultant hydrograms. Experiments of water infiltration in the soil were done by an infiltrometer disc to characterize the spatial variability of hydraulic conductivity and the losses of infiltration in the basin obtaining two sets of data that showed to be lognormally distributed in average equal to 15.8 mm/h and 5.47 mm/h. A theoric study was conduced in the second part of work comprehending the development of hydrologic model distributed. The conception of the model proceed from the premise that allbasin area can be represented by cells derived from a Digital Terrain Model (DTM) specifying in each cell the hydraulic equation - hydrologic. The soil heterogeneity and the precipitation were studied by model simulation considering spatial distributions different to the hydraulic conductivity satured of the soil and to pluvial events. The results pointed out the differences among peak outflow can be more than 100% considering minimum and maximumresolution degrees as the precipitation and affirmed the consensus that the acquaintance of the pluvial spatial distribution is fundamental in the adjustment of hydrologic models distributed.

A partir da segunda metade da década de 2000, novas variáveis, de cunho ambiental, foram introduzidas nas políticas públicas que tratam da relação entre rios, várzeas e áreas urbanas na Cidade de São Paulo, resultando em uma mudança significativa na forma de entender a urbanificação dessas áreas, tanto em âmbito municipal quanto estadual. O objetivo desta tese é analisar o andamento dessas novas políticas públicas, em suas diversas escalas, dos planos aos projetos urbanos, observando as restrições e potencialidades que se apresentam ao seu desenvolvimento. É possível observar, a partir dos estudos realizados, que apesar de a abrangência das intervenções ainda ser pequena, há avanços nas políticas, o que indica que a relação estabelecida com o sistema hídrico no século passado está em processo de transformação. Contudo, permanece o caráter setorial das intervenções, resultando em ações muitas vezes incompletas, que respondem parcialmente às demandas sociais, ambientais e urbanas. Como resposta às questões colocadas pela análise, a tese sugere alguns parâmetros para o planejamento, implantação e gestão de caminhos verdes, parques lineares, ou outros espaços livres públicos em fundos de vale. / After the middle of 2000 decade a number of new environmental variables were brought into the public policies debate around rivers, riverbanks and the management of urban areas in the city of Sao Paulo. This has had a profound impact on how urbanization is perceived both at municipal and state levels. This doctorate thesis\' objective is to review the development of such policies at its multiple levels, as well as its plans and development programmes with special attention to the opportunities and shortcomings its implementation may bring. Results show that even though the scope of interventions is still narrow, there has been improvements in the way these public policies are made, which suggests a trend in the way water has been historically managed for the last century. Nevertheless, the silo approach to water management resources is still prevelent, which leads to insufficient responses to the social and environmental needs of urban development initiatives. In response to the challenge posed by this research, the thesis recommends a set of parameters for the planning, implementation and management of greenways and other public spaces on the urban river corridors.

A importância de avançarmos na discussão de como tornar mais eficaz e significativo o uso e a conservação dos rios em nossas cidades, notadamente em trechos urbanos, mostra-se atualmente cada vez mais iminente, tanto pela expansão desordenada das áreas antropizadas, como pelo consequente alto nível de degradação dos cursos d\"água e da vegetação. Tendo como contexto o estudo de caso da Estância Hidromineral de Monte Alegre do Sul, a dissertação busca caracterizar os corpos d\'água como uma paisagem infra-estrutural e multifuncional através da musealização do seu território de borda e das inter-relações deste com os demais elementos do patrimônio cultural da cidade. Orientada por essa base teórica, apresenta-se uma proposta de intervenção urbana que destaca a transformação da paisagem de borda dos corpos d\"agua em um lugar sensível, de qualidade ambiental e com um conteúdo museológico que gere uma apreensão sobre questões locais assim como sobre toda a sociedade. Uma proposta que adota como premissa a interdisciplinaridade, a valorização dos moradores, destacando seus usos e costumes, e a importância da memória como formadora e transformadora da identidade local, com reflexo direto no desenvolvimento social da própria população. / The importance of moving forward on the discussion of how to make more effective and significant the use and conservation of rivers in our cities, in urban areas, it\"s imminent, as much by the disorderly expansion of the anthropized areas, as by the consequent high level of degradation of the water courses and vegetation. Taking as context the case study of the Estância Hidromineral of Monte Alegre do Sul, the dissertation seeks to characterize the bodies of water as an infrastructure and multifunctional landscape through the musealization of its border territory and the relations with the other elements of the cultural heritage of the City. Guided by this theoretical basis, an urban intervention that highlights the transformation of the border landscape of water bodies in a sensitive place, of environmental quality and of museological content that engenders apprehension about local issues and about the society as well. A proposal that adopts as a premise the interdisciplinarity, the valorization of the residents, highlighting their usages and customs, and the importance of memory as a transformation of local identity, with a direct development of the population itself.

Este é um trabalho sobre as enchentes e as infraestruturas de drenagem na Região Metropolitana de São Paulo. Ele apresenta sua evolução histórica, na forma determinada pela submissão das diretrizes de drenagem aos interesses específicos no aproveitamento do potencial hidrelétrico das águas, na exploração capitalista do espaço de suas margens e na destinação de recursos de saneamento para a abertura de avenidas de fundo de vale. O trabalho observa que através deste processo a capacidade de escoamento das cheias na rede foi mantida em patamares abaixo do necessário, especialmente para atender vazões decorrentes do padrão de expansão da aglomeração, que resultaram em uma alta taxa de impermeabilização do solo e na paulatina ocupação das várzeas. O trabalho analisa a atuação do Estado e o desenvolvimento de diferentes programas de combate às inundações e planos de obra, focando a elaboração do Plano Diretor de Macrodrenagem, a partir de 1998. Então, é verificada a forma como os planos urbanísticos do município de São Paulo e das subprefeituras responderam às soluções propostas no plano de drenagem e os resultados obtidos até o momento com as obras de macrodrenagem. Conclui que a descontinuidade das soluções, a fragmentação das estâncias de planejamento e a ausência de uma unidade metropolitana de fato impedem que se estabeleçam soluções mais eficazes e, especialmente, que garantam a qualificação do espaço construído, levando em conta não apenas a demanda metropolitana pelo serviço prestado, mas também os aspectos sociais, econômicos e ambientais. / This paper focuses on floods and the drainage infrastructure in São Paulo Metropolitan Area. Firstly, it presents its evolution pointing out how economical interests in generating hydroeletric energy as well as in releasing new urban land prevailed over the initial drainage guidelines. It was also observed that confining streams within roads constrained its capacity to a low level to cope with growing peakflows demanded by the expansion of urban area which has led to increasing impervious surface rate. This was compounded by a gradual, but continuous, occupation of floodplains. State actions to deal with the above issues were analysed. Several flood control programs were developed leading to the 1998 Alto Tietê Watershed Macrodrainage Plan proposals. Then, these are studied in the light of how São Paulo\'s urban plans approached this subject, comparing their proposals with works built so far and the consequent outcomes. It is concluded that three main factors prevented that effective solution could come true: discontinuity of approaches, fragmentation of urban planning boards and lack of an actual metropolitan authority. Indeed, concerning drainage system, before these are overcome, many people still will long for urban improvement regarding social, economical and environmental aspects.

A infiltração das águas de chuva dentro dos lotes urbanos é uma possível forma de promover o controle descentralizado do escoamento superficial na origem, com vistas ao gerenciamento das águas pluviais urbanas e conseqüente atenuação das cheias. Neste trabalho, foram conduzidos ensaios de campo com trincheiras de infiltração, em dois solos distintos, um arenoso e outro argiloso, com o objetivo de avaliar quantitativamente o comportamento hidráulico das estruturas de infiltração em resposta a volumes de escoamento. As trincheiras foram alimentadas com volumes de água controlados, e o campo de umidade do experimento foi monitorado com sonda de nêutrons, durante o processo de redistribuição da água no solo. Foi realizada a modelagem matemática do fenômeno bidimensional de infiltração em torno de trincheiras de seção retangular, em resposta à entrada de águas pluviais provenientes de áreas impermeabilizadas contíguas. A comparação entre os resultados experimentais e simulados pela equação bidimensional de Richards indica uma pequena defasagem dos valores de volume infiltrado e umidade do solo nos processos de infiltração e drenagem interna simulados em relação aos observados. A capacidade de infiltração da trincheira mostrou-se maior nos dados observados, possivelmente devido à simplificação de distribuição unimodal dos diâmetros dos poros adotada na modelagem numérica, uma vez que, experimentalmente, observou-se multimodalidade nos dois solos estudados. A curva de van Genuchten é, juntamente com a equação de Richards, a base do modelo computacional, e divergências no seu ajuste em relação aos dados observados podem conduzir a pequenas divergências dos volumes infiltrados e perfis de umidade ao longo do processo de infiltração simulado, em relação ao observado. São apresentadas algumas considerações de dimensionamento sobre a implantação de trincheiras de infiltração em lotes residenciais, bem como discussões com respeito aos planos diretores urbanos. É apresentado um estudo simplificado, baseado no método racional, sobre a redução no hidrograma de cheia proporcionada pelo uso de trincheiras em uma micro bacia urbana, o qual revelou reduções da ordem de até 94% do deflúvio superficial direto gerado pelo lote. / Stormwater infiltration process at the scale of housing is a possible way to promote the decentralized runoff control in order to manage the urban water and to attenuate flood peaks. In this work, field essays with infiltration devices at two different soils, either sandy and clay-loam soils, are assessed in order to study the hydraulic behavior of infiltration trenches to attenuate incoming runoff volume inputs. The infiltration trench experiments set a controlled water supply for specific boundary conditions, and the experimental moisture field were monitored with neutron probe during the water redistribution process at soil core. Bi-dimensional (2D) mathematical modeling is depicted at specific boundary conditions with a rectangular-trench layout, thereby mimicking a potential situation of runoff incoming from adjacent impervious areas. The comparison between experimental and numerical results, simulated by two-dimensional Richards\' equation, shows a small lag-time difference of both infiltrated volumes and soil moisture contents during infiltration and drainage periods. The trench infiltration capacity of observed data appears to be greater than simulated results, possibly due to an overall simplification of a uni-modal, homogeneous pore diameter distribution adopted by the modeling scheme. Experimental retention curves outline indirect evidences of multi-modal, heterogeneous behavior of pore structure. Bon van Genutchen-type retention curve and Richards-momentum equations represent the baseline approach to the computational model of non-saturated soils. Some fitting discrepancies between observed and simulated results could lead to negligible different estimations of infiltrated volumes and moisture profiles. Finally, further discussions on project design and best management practices (BMPs) of infiltration trenches at housing scale as well discussions on urban master plan are outlined herewith. A simplified study, based on rational method, is presented on the reduction of incoming hydrograph with the use of infiltration trenches. Preliminary results perform volume reductions of approximately 94% from incoming runoff generated at housing lots.

<p></p><p></p><p></p><p>In urbanized river basins, sanitary wastewater and urban runoff (non-sanitary water) from urban agglomerations drain to complex engineered networks, are treated at centralized wastewater treatment plants (WWTPs) and discharged to river networks. Discharge from multiple WWTPs distributed in urbanized river basins contributes to impairments of river water-quality and aquatic ecosystem integrity. The size and location of WWTPs are determined by spatial patterns of population in urban agglomerations within a river basin. Economic and engineering constraints determine the combination of wastewater treatment technologies used to meet required environmental regulatory standards for treated wastewater discharged to river networks. Thus, it is necessary to understand the natural-human-engineered networks as coupled systems, to characterize their interrelations, and to understand emergent spatiotemporal patterns and scaling of geochemical and ecological responses. </p><br><p></p><p></p><p>My PhD research involved data-model synthesis, using publicly available data and application of well-established network analysis/modeling synthesis approaches. I present the scope and specific subjects of my PhD project by employing the <i>Drivers-Pressures-Status-Impacts-Responses</i> (<i>DPSIR</i>) framework. The defined research scope is organized as three main themes: (1) River network and urban drainage networks (<i>Foundation</i>-<i>Pathway of Pressures</i>); (2) River network, human population, and WWTPs (<i>Foundation</i>-<i>Drivers</i>-<i>Pathway of Pressures</i>); and (3) Nutrient loads and their impacts at reach- and basin-scales (<i>Pressures</i>-<i>Impacts</i>).</p><br><p></p><p></p><p>Three inter-related research topics are: (1) the similarities and differences in scaling and topology of engineered urban drainage networks (UDNs) in two cities, and UDN evolution over decades; (2) the scaling and spatial organization of three attributes: human population (POP), population equivalents (PE; the aggregated population served by each WWTP), and the number/sizes of WWTPs using geo-referenced data for WWTPs in three large urbanized basins in Germany; and (3) the scaling of nutrient loads (P and N) discharged from ~845 WWTPs (five class-sizes) in urbanized Weser River basin in Germany, and likely water-quality impacts from point- and diffuse- nutrient sources. </p><br><p></p><p></p><p>I investigate the UDN scaling using two power-law scaling characteristics widely employed for river networks: (1) Hack’s law (length-area power-law relationship), and (2) exceedance probability distribution of upstream contributing area. For the smallest UDNs, length-area scales linearly, but power-law scaling emerges as the UDNs grow. While area-exceedance plots for river networks are abruptly truncated, those for UDNs display exponential tempering. The tempering parameter decreases as the UDNs grow, implying that the distribution evolves in time to resemble those for river networks. However, the power-law exponent for mature UDNs tends to be larger than the range reported for river networks. Differences in generative processes and engineering design constraints contribute to observed differences in the evolution of UDNs and river networks, including subnet heterogeneity and non-random branching.</p><br><p></p><p></p><p>In this study, I also examine the spatial patterns of POP, PE, and WWTPs from two perspectives by employing fractal river networks as structural platforms: spatial hierarchy (stream order) and patterns along longitudinal flow paths (width function). I propose three dimensionless scaling indices to quantify: (1) human settlement preferences by stream order, (2) non-sanitary flow contribution to total wastewater treated at WWTPs, and (3) degree of centralization in WWTPs locations. I select as case studies three large urbanized river basins (Weser, Elbe, and Rhine), home to about 70% of the population in Germany. Across the three river basins, the study shows scale-invariant distributions for each of the three attributes with stream order, quantified using extended Horton scaling ratios; a weak downstream clustering of POP in the three basins. Variations in PE clustering among different class-sizes of WWTPs reflect the size, number, and locations of urban agglomerations in these catchments. <b></b></p><br><p></p><p></p><p>WWTP effluents have impacts on hydrologic attributes and water quality of receiving river bodies at the reach- and basin-scales. I analyze the adverse impacts of WWTP discharges for the Weser River basin (Germany), at two steady river discharge conditions (median flow; low-flow). This study shows that significant variability in treated wastewater discharge within and among different five class-sizes WWTPs, and variability of river discharge within the stream order <3, contribute to large variations in capacity to dilute WWTP nutrient loads. For the median flow, reach-scale water quality impairment assessed by nutrient concentration is likely at 136 (~16%) locations for P and 15 locations (~2%) for N. About 90% of the impaired locations are the stream order < 3. At basin-scale analysis, considering in stream uptake resulted 225 (~27%) P-impaired streams, which was ~5% reduction from considering only dilution. This result suggests the dominant role of dilution in the Weser River basin. Under the low flow conditions, water quality impaired locations are likely double than the median flow status for the analyses. This study for the Weser River basin reveals that the role of in-stream uptake diminishes along the flow paths, while dilution in larger streams (4≤ stream order ≤7) minimizes the impact of WWTP loads. </p><br><p></p><p></p><p>Furthermore, I investigate eutrophication risk from spatially heterogeneous diffuse- and point-source P loads in the Weser River basin, using the basin-scale network model with in-stream losses (nutrient uptake).Considering long-term shifts in P loads for three representative periods, my analysis shows that P loads from diffuse-sources, mainly from agricultural areas, played a dominant role in contributing to eutrophication risk since 2000s, because of ~87% reduction of point-source P loads compared to 1980s through the implementation of the EU WFD. Nevertheless, point-sources discharged to smaller streams (stream order < 3) pose amplification effects on water quality impairment, consistent with the reach-scale analyses only for WWTPs effluents. Comparing to the long-term water quality monitoring data, I demonstrate that point-sources loads are the primary contributors for eutrophication in smaller streams, whereas diffuse-source loads mainly from agricultural areas address eutrophication in larger streams. The results are reflective of spatial patterns of WWTPs and land cover in the Weser River basin.</p><br><p></p><p></p><p>Through data-model synthesis, I identify the characteristics of the coupled natural (rivers) – humans – engineered (urban drainage infrastructure) systems (CNHES), inspired by analogy, coexistence, and causality across the coupled networks in urbanized river basins. The quantitative measures and the basin-scale network model presented in my PhD project could extend to other large urbanized basins for better understanding the spatial distribution patterns of the CNHES and the resultant impacts on river water-quality impairment.</p><p><br></p><p></p>