Tesis por compendio / [ES] La rehabilitación de las redes de drenaje es uno de los procesos fundamentales que los administradores y responsables de la gestión de redes de drenaje deben implementar para adaptar las redes defectuosas a los efectos adversos del cambio climático y la urbanización. Las soluciones tradicionales pasan por la sustitución de tuberías o la instalación de tanques de tormenta (TT). En esta tesis, el escenario propuesto combina la sustitución de tuberías y la instalación de TT para la rehabilitación de redes de drenaje. Los resultados de varias simulaciones en varias redes mostraron que el uso combinado de la sustitución de tuberías y la instalación de TT en la rehabilitación de redes de drenaje proporciona mejores resultados que la separación de los dos escenarios de rehabilitación. Tal metodología de rehabilitación necesita un tiempo de computación elevado para proporcionar soluciones aceptables que a menudo se encuentran atrapados en mínimos locales. El objetivo de esta tesis es proponer una metodología que permita obtener mejores resultados durante la rehabilitación de redes de drenaje considerando el uso combinado de la sustitución de tuberías y la instalación de TT. La metodología debe considerar la reducción del espacio de búsqueda (SSR). Cuatro opciones claves están combinadas para lograr reducir el espacio de búsqueda del problema. Estas opciones son: Reducir la cantidad de nudos en los que podrían instalarse los TT. Reducir el número de líneas en las que podría haber un cambio en el diámetro Reducir la discretización que se hace de la sección de cada uno de los TT. Reducir el número de diámetros candidatos en las tuberías. Una vez que se reduce el espacio de búsqueda, el algoritmo pseudo genético (APG) utilizado en esta tesis para la optimización mono-objetivo puede explorar más partes del espacio de búsqueda en menos tiempo. Lo que resulta es la obtención de mejores resultados. Por la optimización multiobjetivo, el NSGA-II utilizado puede proporcionar frentes de Pareto rápidamente para los diferentes escenarios considerados después del proceso de optimización. El objetivo general se dividió en objetivos específicos que se detallan a continuación: El primer objetivo específico consiste en formular un problema de optimización que verifique que la rehabilitación teniendo en cuenta la instalación de los TT y la sustitución de las tuberías proporciona mejores resultados que cualquiera de las dos estrategias implementadas por separado. Evaluar adecuadamente las funciones de costes utilizadas para formar las funciones objetivo constituye el segundo objetivo específico. Los diferentes costes considerados son: costes de sustitución de tuberías, costes de instalación de TT y costes de daños por inundación. El tercer objetivo específico es desarrollar un modelo de rehabilitación considerando la instalación de TT y la sustitución de tuberías, basado en APG y el Modelo SWMM. Los costes de inversiones y los costes de daños por inundaciones no se pueden sumar debido a sus tipos. Los costes de inversiones son reales mientras que los costes de daños por inundaciones son futuribles, dependen de la probabilidad de ocurrencia de la lluvia. Por lo tanto, el cuarto objetivo específico de esta tesis es proponer un algoritmo multiobjetivo evolucionario para la rehabilitación de redes de drenaje considerando la instalación de TT y la sustitución de tuberías. Para la optimización de un mono objetivo y multiobjetivo, el tiempo de cálculo es elevado. También las soluciones objetivas estaban atrapadas en mínimos locales. El quinto objetivo es proponer una metodología de reducción del espacio de búsqueda (SSR) para resolver este problema. El sexto objetivo específico consiste en llevar a cabo un análisis de sensibilidad para verificar los efectos del SSR en el resultado final del proceso de optimización. Por lo tanto, se seleccionaron diferentes tamaños de poblac / [CA] La rehabilitació de les xarxes de drenatge és un dels gestors de processos fonamentals i la necessitat responsable d'implementar per adaptar les xarxes defectuoses als efectes adversos del canvi climàtic i la urbanització. A la literatura, la installació de canonades o substitució de canonades són els dos escenaris presentats pels autors. En aquesta tesi, un tercer escenari proposa combinar la installació de canonades de substitució i tancs de tempesta (TT) per a la rehabilitació de xarxes de drenatge. Els resultats de diverses simulacions a diverses xarxes van mostrar que la combinació d'ús de canvis de substitució de canonades i TT a la rehabilitació de xarxes de drenatge proporciona millors resultats que la separació dels dos escenaris de rehabilitació. Desafortunadament, aquesta metodologia de rehabilitació requereix temps de càlcul elevat per proporcionar solucions acceptables que sovint es troben en mínim local. L'objectiu d'aquesta tesi és proposar una metodologia que permeti reduir el temps de càlcul i obtenir millors resultats durant la rehabilitació de la xarxa de drenatge considerant l'ús combinat de la instal·lació dels TT de substitució de canonades. L'estratègia adoptada combina, en una metodologia estructurada, quatre opcions clau per reduir l'espai de cerca del problema: Reduir el nombre de nodes en què podrien instal·lar-se els TT. Reduir el nombre de línies en què podria haver-hi un canvi de diàmetre Reduir la discretització que es fa de la secció de cadascun dels TT. Reduir la quantitat de diàmetres candidats à les canonades. Un cop reduït l'espai de cerca, l'algorisme pseudo-genètic (PGA) que s'utilitza en aquesta tesi per a l'optimització d'un únic objectiu (SO) pot explorar fàcilment l'espai de cerca en menys temps, resultant en obtenir millors resultats. Per a l'optimització del MO, la NSGA-II pot proporcionar fronts de Pareto ràpidament per als diferents escenaris considerats després del procés d'optimització. L'objectiu general es va a dividir en objectius específics detallats a continuació: El primer objectiu específic consisteix a formular un problema d'optimització que verifiqui que la rehabilitació considerant la instal·lació de TT i la seva substitució proporciona millors resultats que qualsevol de les dues estratègies implementades per separat. Valorar adequadament les funcions de cost que s'utilitzen per formar les funcions objectives, i constitueix el segon objectiu específic. Els diferents costes considerats són: Costes d'inversions i costes de danys a les inundacions. El tercer objectiu específic és desenvolupar un model de rehabilitació considerant la instal·lació de TT i la substitució de canonades, basant-se en el PGA i el model SWMM. Els costos d'inversions i els costos de danys per inundacions no es poden sumar a causa d'un tipus. Els costes d'inversions són reals mentre els costes d'anuncis per a les futures fonts del futur són dependents de la probabilitat d'obertura de la pluja. Per tant, el cos objectiu específic d'aquesta tesi és propiciar un algorisme multiobjetiu evolutiu per a la rehabilitació de la xarxa de navegació considerant la instal·lació de TT i la substitució de tuberies. Per a l'optimització d'un únic objectiu i multi-objectiu, el temps de càlcul s'eleva. També es va sospitar que les solucions objectives eren atrapades en els mínims locals. El cinquè objectiu és proposar una metodologia de la reducció de l'espai de cerca (SSR) per resoldre aquest problema El sisè objectiu específic consisteix a realitzar una anàlisi de sensibilitat per verificar els efectes de SSR sobre el resultat final del procés d'optimització. Per tant, es van seleccionar diferents grandàries de població i valors de criteris de parada i es van realitzar simulacions per a diferents configuracions. El setè objectiu específic d'aquesta tesi és proposar una nova metodologia de rehabilitació considerant la tècnica / [EN] Drainage networks rehabilitation is one of the fundamental process that managers and responsible need to implement to adapt defective networks to climate change and urbanization adverse effects. In the literature, pipes substitution or storm tanks (STs) installation are the two scenarios presented by authors. In this thesis, a third scenario proposed combine pipes substitution and STs installation for drainage networks rehabilitation. Results of several simulations on various networks showed that the combine use of pipes substitution and STs installation in drainage networks rehabilitation provides better results than separation of the two rehabilitation scenarios. Unfortunately, such rehabilitation methodologies are computationally time consumers. They need much time to provide acceptable solutions which are often caught up in local minima. The aim of this thesis is to propose a drainage networks rehabilitation methodology based on the combine use of pipes substitution and STs installation. The methodology considers search space reduction (SSR) technique. The adopted strategy combines in a structured methodology four key options aiming at reducing the search space (SS) of the problem: Reduce the number of nodes in which STs could potentially be installed. Reduce the number of lines in which there could potentially be a change in diameter Reduce the discretization that is made of the section of each of the STs. Reduce the number of candidate diameters in the pipes. Once the search space is reduced, the pseudo genetic algorithm (PGA) used in this thesis for single objective (SO) optimization can easily explore the search space in less time resulting in the obtention of better results. For the MO optimization, the NSGA-II can provide rapidly Pareto fronts for the different considered scenarios after the optimization process. The general objective was divided in specific objectives detailed as follow: The first specific objective consists of formulate an optimization problem that verifies that rehabilitation considering STs installation and pipes substitution provides better results than any of the two strategies implemented separately. Adequately assess the cost functions used to form the objective functions constitutes the second specific objective. The different costs considered are: Investments costs and flood damage costs. The third specific objective is to develop a rehabilitation model considering STs installation and pipes substitution, based on PGA and the Storm Water management Model. Investment costs and flood damage costs could not be summed due to their types. Investment costs are reals while, flood damage costs depend on the rainfall probability. So, the fourth specific objective of this thesis is to propose a MOEA for drainage networks rehabilitation considering STs installation and pipes substitution. For SO and Multi-objective (MO) optimization, the computation time is elevated. It was also suspected that the objective solutions were caught up in local minima. The fifth objective is to propose an SSR methodology to solve this issue The sixth specific objective consist of carry out a sensitivity analysis to verify the effects of the SSR on the final result of the optimization process. So, different population sizes and stop criteria values were selected and simulation for different configurations were performed. The seventh specific objective of this thesis is to propose a new rehabilitation methodology considering SSR technique for MO optimization. For each specific objective presented in this thesis, an application to a drainage network has been made and the obtained results were satisfactory. A simple network was used to apply the simple optimization methodology based on PGA algorithm A medium size network was used to apply the SO optimization, the MO optimization and the SSR methodology. Finally, a large and mesh network was used to apply the MO optimization methodology considering SSR. / Ngamalieu Nengoue, UA. (2019). URBAN DRAINAGE NETWORK REHABILITATION CONSIDERING STORM TANK INSTALLATION AND PIPE SUBSTITUTION [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129869 / Compendio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The urban growth and the disordered occupation of cities have increased the frequency and severity of flooding in urban areas, which occur mainly due to the modification on rainwater natural infiltration, as a result of soil imperviousness increase. The use of compensatory techniques (CT) for stormwater control has been encouraged through public polices, attempting to apply for sustainable solutions to mitigate the urbanization´s impact. An alternative already widespread in some Brazilian cities is the use of micro reservoirs (MR), which temporarily store volumes from impervious areas, and gradually emptying the water stored. Along this requirement, implementation of Rainwater Harvesting Reservoirs (RHR) to non-potable purposes is often encouraged in order to reduce the consumption of drinking water for less noble purposes, and to preserve the fountainheads. Some bibliographies suggest that in addition to these benefits, the RHR can be considered a CT also, once it stores the stormwater runoff, and therefore, in some cities where the MR is required, many buildings are already using the RHR to replace it. However, there are not many conclusive studies related to the real benefits and impacts that capturing rainwater and its use have on micro drainage networks, and specifically if such technique can be considered as a compensatory one. Thus, the main objective of this research was to evaluate whether RHR can be considered as an alternative to promote the quantitative stormwater control. For that, a comparative analysis was made between the impact that RHR use generates on micro drainage flows and networks, and the impact generated on a MR containing system. Such analysis was performed through a modeling of a urban watershed from Porto Alegre / RS, with 977 ha, 30.720 standard lots and around 70 km of micro drainage networks. The simulated MRs were designed according to the Decree No. 15.371/06 of the city of Porto Alegre, which aim to control the runoff at the source and it resulted in volumes of 3.13 m³ and 3.75 m³ for rainfall project with return period of 5 and 10 years (CP-CP-TR5 and TR10), respectively, answering to the allowable flow restriction at the lot outlet (VR = 0.624 L / s). The micro drainage networks were designed for both situations, with and without MRs, for CP-TR5 and CP-TR10. For sizing of the RHRs a continuous simulation of 12 years of precipitation data and demands series for non-potable uses data was performed, both with time step equal 5 minutes, resulting in volumes of 5.000, 10.000 and 15.000 liters due to the achieved service guarantee. These volumes of RHRs replaced the MRs and new modeling were performed considering observed rainfall data real from the continuum time series. It was found that the RHRs were not effective to maintain the VR at lots outlet, and the restriction value was exceeded for several times. For the simulated time seriess only the volume of 750 m³ would be appropriate to ensure only one offense within 10 years of simulation. That occurs because must have sufficient volume to store the expected drained volume, without spillage, regardless of the reservoir storage condition. However, if there is a very large storage capacity and demands are comparatively small, the reservoir does not empty. It was found, therefore, that exists an antagonism when trying to use the RHR for two functions: runoff control and water supply for non-potable purposes demand, since the attempt to ensure the fulfillment to the first function prevents the deployment of such large volumes. Overtopping of RHRs to 12 critical simulated events committed the microdrainage networks capacity, generating flooding in the streets along several drainage network ranges. Considering the same 12 critical events and MRs in lots were identified only four overflowing and lower overflows, which ended up committing a lower extent of drainage networks. Therefore, based on analysis of the continuous simulation with RHRs, it was found that it is not possible to consider it an equivalent technique to the MRs for storm water runoff control, unless the reservation volumes are extremely high, which would make its implementation on a few square meters lot impossible. / O crescimento urbano e a ocupação desordenada das cidades têm aumentado a frequência e a severidade das enchentes em áreas urbanas, que ocorrem, principalmente, devido à modificação nas condições naturais de infiltração das águas pluviais, decorrentes do aumento da impermeabilização do solo. Em busca de soluções sustentáveis para mitigar os impactos da urbanização, as políticas públicas vêm incentivando o uso de técnicas compensatórias (TC) para o controle do escoamento superficial. Uma alternativa já difundida em algumas cidades brasileiras é o uso de microrreservatório (MR), que armazena temporariamente os volumes oriundos do escoamento das áreas impermeáveis, esvaziando gradativamente a água armazenada. Paralelamente a essa exigência, a implementação de reservatórios para o aproveitamento da água da chuva (RAAC) com fins não potáveis vem sendo incentivada, com o intuito de reduzir o consumo de água tratada para fins menos nobres e preservar os mananciais. Algumas bibliografias sugerem que além desses benefícios, o RAAC pode ser considerado igualmente uma TC, já que armazenaria o escoamento pluvial, e por essa razão, em algumas cidades onde o MR é exigido, muitas edificações já estão utilizando o RAAC em substituição a este. No entanto, verifica-se uma falta de estudos conclusivos a respeito dos reais benefícios e impactos que a captação da água da chuva e seu aproveitamento têm sobre as redes de microdrenagem pluvial e, especificamente, se esta técnica pode ser considerada como compensatória. Assim, o principal objetivo desta pesquisa foi avaliar se os RAACs podem ser considerados como medidas para o controle quantitativo do escoamento pluvial. Para isso, foi realizada uma análise comparativa do impacto que a sua utilização gera sobre as vazões e redes de microdrenagem, com o impacto gerado em um sistema com MR. A análise foi realizada mediante modelagem matemática de uma bacia hidrográfica urbana da cidade de Porto Alegre/RS, com 977 ha, 30.720 lotes padrão e cerca de 70 km de redes de microdrenagem. Os MRs simulados foram dimensionados de acordo com o Decreto n° 15.371/06 da cidade de Porto Alegre para o controle do escoamento na fonte, resultando em volumes de 3,13 m³ e 3,75 m³, para chuvas de projeto com 5 e 10 anos de período de recorrência (CP-TR5 e CP-TR10), respectivamente, atendendo à vazão de restrição permissível na saída do lote (VR = 0,624 L/s). As redes de microdrenagem foram dimensionadas para as situações que contemplaram os MRs e para a situação sem os MRs, para CP-TR5 e CP-TR10. Para o dimensionamento dos RAACs foi realizada uma simulação contínua de 12 anos de dados de chuvas e série de demandas para fins não potáveis, ambas com intervalo de tempo de 5 minutos, tendo sido determinados os volumes de 5.000, 10.000 e 15.000 litros como os mais adequados para a edificação, em razão da garantia de atendimento atingida. Esses volumes de RAACs substituíram os MRs e novas modelagens foram realizadas considerando tanto eventos de projeto, como as chuvas reais da série contínua. Verificou-se que os RAACs não são eficientes na manutenção da VR na saída dos lotes, sendo que ao longo da série história simulada a mesma foi infringida várias vezes. Para a série histórica simulada apenas um volume de 750 m³ seria adequado para garantir apenas uma infração em 10 anos da simulação. Isso ocorre porque deve haver volume de espera suficiente para armazenar os volumes escoados, sem que haja vertimento, independentemente da condição de armazenamento do reservatório; no entanto, se existe uma capacidade de armazenamento muito grande, e as demandas são comparativamente pequenas, o reservatório não esvazia. Constatou-se, dessa forma, que existe um antagonismo quando se pretende utilizar o RAAC para as duas funções: controle de escoamento superficial e garantia de atendimento à demanda com fins não potáveis, visto que a tentativa de garantir o cumprimento da primeira função inviabiliza a implantação de volumes tão grandes. O extravasamento dos RAACs para 12 eventos críticos simulados comprometeu a capacidade das redes de microdrenagem, gerando armazenamento de água nas ruas ao longo de vários trechos. Considerando os mesmos 12 eventos críticos e os MRs nos lotes foram identificados apenas 4 extravasamentos e menores vazões extravasadas, o que acabou comprometendo uma menor extensão das redes de drenagem. Portanto, com base nas análises da simulação contínua com os RAACs, verificou-se que não é possível considerá-lo uma técnica equivalente aos MRs para o controle do escoamento pluvial, a menos que os volumes de reservação sejam extremamente elevados, o que tornaria impossível a sua implementação em um lote de poucos metros quadrados.

<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>