Frameworks for urban water sustainability

Integrated water management, sustainable water management, water sensitive cities, and other formulations are often presented as the latest in a series of paradigms of water management. This implies a unified approach, while urban water debates reflect a wide diversity of political, social, and technical viewpoints. Five distinct but overlapping frameworks for urban water sustainability are evident in research, policy and practice, reflecting wider environmental theory, politics, and discourse. Sustainable development is based on meeting the needs for water and sanitation of the urban poor. Ecological modernization focuses on policies to improve water efficiency and treatment through technological innovation and individual behavior change. Socio‐technical framings aim to understand how change in water systems occurs across physical and institutional scales and addresses the co‐evolution of infrastructures, cultures, and everyday practices. Urban political ecology analyses water infrastructure in terms of relationships of power, pointing to the unequal distribution of costs and benefits of urban water management for the environment and citizens. Radical ecology addresses the relationship between human culture and non‐human nature, proposing fundamental reorganization of society to solve ecological and hydrological crises. Characterizing alternate frameworks of urban water sustainability provides clarity on the underlying assumptions, methods, and politics across a diversity of approaches. Frameworks may be deployed strategically to deliver policy impact, or may reflect deeply held political or epistemological standpoints. Understanding different conceptions of urban water sustainability provides the basis for more constructive dialogue and debate about water and its role in sustainable cites. This article is categorized under: Engineering Water > Planning Water Human Water > Water Governance Water and Life > Conservation, Management, and Awarenes

Integrated management of water resources in urban water system: Water Sensitive Urban Development as a strategic approach

[ES] El medio urbano no es ajeno a la gestión integrada del recurso hídrico, que incluye, necesariamente, el concepto de unidad de cuenca y de gobernanza. El tradicional concepto de ciclo del agua urbana, que incorpora de un modo muy lineal los servicios de abastecimiento y saneamiento, debe ser sustituido por una visión más integral y sistémica, donde el agua se vincula con el planeamiento y el desarrollo urbano y con las políticas de sostenibilidad. Se puede hablar de sistema de agua urbana. Esta globalidad de acción no es algo de lo que podamos sustraernos, ya que la legislación cada vez más orienta a las administraciones a considerar aspectos sistémicos y ambientales a la hora de gestionar, por ejemplo, los sistemas de saneamiento y drenaje. La plasmación práctica de todo este conglomerado de interacciones ya toma forma en algunos países, en los que se comienza a hablar de “Low Impact Development” (LID) o “Water Sensitivity Urban Design” (WSUD). Se propone integrar este nuevo enfoque estratégico bajo la denominación: Desarrollo Urbano Sensible al Agua (DUSA). Con el impulso del enfoque DUSA, los actuales sistemas de agua urbana (concebidos originalmente bajo el concepto tradicional de ciclo de agua urbana) pueden transformarse, conceptual y físicamente, para una gestión integrada del sistema del agua urbana en los nuevos modelos de desarrollo urbanos sostenible. Asimismo se presenta la aplicación del nuevo enfoque DUSA a la gestión de la contaminación asociada a las aguas pluviales en el sistema de agua urbana, incluyendo los avances en normativa e incorporación de técnicas en España.[EN] The urban environment has to be concerned with the integrated water resources management, which necessarily includes the concept of basin unity and governance. The traditional urban water cycle framework, which includes water supply, sewerage and wastewater treatment services, is being replaced by a holistic and systemic concept, where water is associated with urbanism and sustainability policies. This global point of view cannot be ignored as new regulations demand systemic and environmental approaches to the administrations, for instance, in the management of urban drainage and sewerage systems. The practical expression of this whole cluster interactions is beginning to take shape in several countries, with the definition of Low Impact Development and Water Sensitivity Urban Design concepts. Intends to integrate this new strategic approach under the name: “Water Sensitive Urban Development” (WSUD). With WSUD approach, the current urban water systems (originally conceived under the traditional concept of urban water cycle) can be transformed, conceptual and physically, for an integrated management of the urban water system in new models of sustainable urban development. A WSUD implementing new approach to the management of pollution associated with stormwater in the urban water system is also presented, including advances in environmental regulations and incorporation of several techniques in Spain.Suárez López, JJ.; Puertas, J.; Anta, J.; Jácome, A.; Álvarez-Campana, JM. (2014). Gestión integrada de los recursos hídricos en el sistema agua urbana: Desarrollo Urbano Sensible al Agua como enfoque estratégico. Ingeniería del agua. 18(1):111-123. https://doi.org/10.4995/ia.2014.3173OJS111123181Benedict, M.A., McMahom, E.T. 2006. Green Infraestructures: Linking Landscapes and Communities. Island Press, Washington DC, USA.CE (2010). 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Simulation of Infrastructure Options for Urban Water Management in Two Urban Catchments in Bogotá, Colombia

Urban areas are currently experiencing rapid growth, which brings with it increases in the population, the expansion of impervious surfaces, and an overall jump in the environmental and hydrological impact. To mitigate such an impact, different strategies proposed to tackle this problem often vary; for example, stormwater tanks, the reuse of wastewater and grey water, the installation of equipment to reduce water consumption, and education-based approaches. Consequently, this article presents the simulation and evaluation of implementing infrastructure options (stormwater harvesting, reuse of industrial waters, water-saving technology in residential sectors, and reuse of water from washing machines) for managing urban water in two urban catchments (Fucha and Tunjuelo) in Bogotá, Colombia, over three periods: baseline, 10 years, and 20 years. The simulation was performed using the software Urban Volume Quality (UVQ) and revealed a possible reduction in drinking water consumption of up to 47% for the Fucha Catchment and 40% for the Tunjuelo Catchment; with respect to wastewater, the reduction was up to 20% for the Fucha Catchment and 25% for the Tunjuelo Catchment. Lastly, two scenarios were evaluated in terms of potential savings related to water supply and sewage fees. The implementation of strategies 3 and 6 insofar as these two strategies impacted the hydric resources. Therefore, there would be a significant reduction in contaminant loads and notable economic benefits attributable to implementing these strategies

Integrated Evaluation of Hybrid Water Supply Systems Using a PROMETHEE-GAIA Approach

There are pressures on existing centralized water infrastructures in urban centers which justify the search for alternatives. An increasingly important alternative is to shift from centralized to hybrid systems, often in response to climate variability and demographic changes. In a hybrid system, water is supplied and discharged through a mix of centralized and decentralized systems. There is usually no single objective that justifies the choice of hybrid water systems, but they typically are justified based on the consideration of a number of different criteria in order to evaluate the overall quality of service provision. The most important criteria include meeting water demand, as well as reducing demand for fresh water and instead using local alternative water supplies. Integration of multiple objectives to evaluate the hybrid water supply systems can be accomplished by multi-criteria decision aid techniques. This paper evaluates a number of hybrid water supply scenarios using a case study based on the Northern Growth Area of Melbourne, Australia. It uses the Preference Ranking Organization METHod for Enrichment Evaluations (PROMETHEE) and Geometrical Analysis for Interactive Decision Aid (GAIA), one of the multi-criteria decision-making methods through D-Sight software, to rank the hybrid water supply scenarios, and this ranking is validated by means of sensitivity analysis. The centralized system combined with stormwater harvesting and the centralized system combined with treated wastewater and rainwater tanks yielded the first and second most preferred scenarios, while the centralized water supply system combined with treated wastewater yielded the worst hybrid water supply option

Quantitative UWS performance model: WaterMet2

© TRUST 2014The report presents a detailed description of the WaterMet2 methodology and tool as a quantitative urban water system (UWS) performance model. The WaterMet2 model is described in three distinct parts. Modelling concepts of different components in WaterMet2 are first described. It provides an overview of the principle flows/fluxes modelled in spatial and temporal scales in WaterMet2 and how they are modelled within the framework of mass balance equations in four subsystems (water supply, sub-catchment, wastewater and water resource recovery). The second part describes the WaterMet2 software. This consists of an overview of WaterMet2 on how input data are prepared, how to run a simulation and finally how to retrieve results in different formats. This part also introduces the WaterMet2 toolkit functions which can be used by other programming languages to call a WaterMet2 simulation model. In the third part, WaterMet2 is illustrated using the city of Oslo UWS as a generic reference model. This part first describes building and calibrating a WaterMet2 model for the existing UWS which faces water scarcity problems for a 30-year planning horizon starting from year 2011. Then, it examines two alternative intervention options (i.e. adding new water resource and water treatment options) which are supported by the WaterMet2. These options are examined for the UWS model and the improvements are compared to the business-as-usual case.European Union Seventh Framework Programme (FP7/2007-2013

Quantifying the potential for potable water savings in the Liesbeek River catchment

Includes bibliographical references.The security of South Africa’s water resources has been identified as a major issue affecting the country’s potential for socio-economic expansion. With the realisation that current water management interventions require significant improvement, there has been growing interest in finding more effective approaches to water management. This dissertation aims to quantify the potential potable water savings that could be achieved through the implementation of selected sustainable water management interventions in the Liesbeek River catchment, Cape Town. The current water use model was constructed in the form of a water balance, using data collected from the catchment

Environmental and economic assessment of urban water systems and evolution towards a sustainable model: case study of La Vall de Boí (Lleida, Spain)

To improve the actual urban water system in la Vall de Boí in order to achieve a more sustainable model. By analysing a selected material and energy flows as well as a selected environmental impacts associated with the metabolism of the urban water system, a study of the current sustainability level will be done with a MFA-LCA approach. Then, certain interventions based on sustainable development will be studied and compared with specific KPIs for each intervention and in relation with the current situation.The upcoming sustainability challenges in the urban water systems are driving management and planning focus towards sustainability in a more holistic and integrated view. In this work, the Dynamic Metabolism Model (DMM), based on the LCA and MFA approach, has been used to analyse the inputs and outputs from the urban water system (UWS) metabolism to give sustainability assessment. It constitutes the first step to achieve a full internalisation of costs of the UWS. This model has been carried out in a real case study in the Vall de Boí, Pyrenees, Spain. The present analysis, as well as future interventions and scenarios, are developed after consulting stakeholders involved. The impact assessment has shown that the greatest impact is the in-house and the WWTPs energy demand, so the interventions have been designed to overcome them reducing them, designing green infrastructure and using ICTs to improve the efficiency of the current assets. In this work, an integral solution has been also designed modelling water policies to understand their impacts on the UWS thanks to specific calculated KPIs. The DMM has been demonstrated as a powerful tool to comprehensively understand the impacts of specific interventions strategies that can usefully help stakeholders into the decision-making process. The results of the improvement assessment showed a reduction up to 24% of the GWP and AP impacts, and up to 49% of the EP impacts. The results also show that a sustainable urban water planning and policy, decoupled from the economic dimension can be achieved while demonstrating that can represent an opportunity to reduce costs and generate business too

Bacterial diversity and antibiotic resistance from the water source to the tap

Water is one of the most important habitats for bacteria in the environment. The continuous flux in the urban water cycle carries water through many places, dragging bacteria and numerous chemical contaminants. This makes of water one of the most important vehicles, not only for the dissemination of the chemical substances, but also for the dissemination of organisms and, consequently, the respective resistance genes in the environment. The main goal of this study was to investigate if drinking water production and distribution could represent a hotspot for the proliferation, selection or incoming of antibiotic resistant bacteria, and the likelihood of these organisms to reach the final consumer, via tap water. In order to meet this objective, the study was planned aiming the tracking of bacterial communities and individual isolates from the source to the tap. Firstly, the abundance and diversity of bacteria in raw, treated and final (tap) water was characterized using culture-dependent and culture-independent (16S rRNA-DGGE) approaches. Both approaches showed that the water treatment reduced the bacterial counts, diversity and cultivability, promoting also a shift in the cultivable bacterial community from predominantly Gram-negative to predominately Gram-positive bacteria. Nevertheless, this effect was reverted, and in tap water Gram-negative bacteria became predominant. Moreover, in tap water total and cultivable bacteria counts were higher than in the disinfected water collected from the distribution system. These results suggest the occurrence of bacterial regrowth and/or biofilm formation over the distribution system or at tap level. Although changes in the bacterial community structure over the water circuit were observed, the predominant phylum detected, by 16S rRNA-DGGE, was the same in all the sampling points – Proteobacteria (mainly of classes Alpha, Beta and Gamma). Culture-dependent and culture-independent approaches were compared to assess which groups might be overlooked by cultivation procedures. In order to have a clear evidence of the bacterial groups which could be overlapped using those procedures, culture-dependent and two culture-independent (16S rRNA gene based DGGE and 454 pyrosequencing) methods were compared for their ability to survey the bacterial diversity of a sample. Such a comparison showed that although the different methods detected the same predominant phyla, different bacteria were targeted. Thus, besides the previous expectation that culture-independent methods would detect more bacterial groups than cultivation methods, it was also concluded that both approaches target different bacterial populations. Based on the study of the bacterial diversity, mainly of cultivable bacteria, and in the literature available, two of the most relevant taxonomic groups detected in drinking waters, due to the widespread distribution and/or abundance, were further studied. Thus, Sphingomonadaceae and Pseudomonas spp. isolated from the source to the tap were studied for species diversity, intra-species variability and potential to spread antibiotic resistance. Although members of the same species were detected in different sampled sites, the same genotype was never detected in raw water and in tap water. According to these results, the hypothesis that bacteria detected in tap water had origin in the water source had to be rejected. Other hypotheses, namely the occurrence of regrowth in water pipelines or taps or an external contamination downstream the sampled sites in the distribution system, emerged from this study. Additionally, the analysis of the antibiotic resistance profiles confirmed that both Sphingomonadaceae and Pseudomonas spp. are potential reservoirs of antibiotic resistance. Nevertheless, clear evidences of horizontal gene transfer were not obtained in this study. Indeed, antibiotic resistance patterns were mainly species-, rather than site- or strain-related, suggesting the importance of vertical resistance transmission in water bacteria. Some antibiotic resistance phenotypes were observed in tap water but not upstream. Examples of this situation were the resistance phenotypes to ampicillin-sulbactam, piperacillin plus tazobactam-pyocyanin, imipenem, ceftazidime, cefepime, gentamicin or tobramycin in Sphingomonadaceae, or to streptomycin and rifampicin in Pseudomonas spp. Cultivation-independent methods show invariably that most of the bacteria in a community are unknown, which means that were never cultivated, characterized and integrated in a validly named taxonomic group. Bacterial taxonomy can have a contribution to gradually narrow the tranche corresponding to the unknown bacteria. In this study a new species name Bacillus purgationiresistens sp. nov. was proposed, based in a single isolate recovered from treated water. Drinking water was confirmed as a potential hotspot for the spreading of antibiotic resistant bacteria, with emphasis on the transfer environment-humans.A água é um dos habitats mais importantes para as bactérias no ambiente. O fluxo contínuo da água, nomeadamente ao longo do seu ciclo urbano, faz com que chegue a muitos locais, arrastando microrganismos e inúmeros contaminantes químicos. Isto faz da água um dos veículos mais importantes para a disseminação no ambiente, não só de substâncias químicas, mas também de bactérias e, consequentemente, dos respetivos genes de resistência. O principal objetivo deste estudo foi investigar se a produção e distribuição de água de consumo poderá representar um ponto-chave para a proliferação, seleção e entrada de bactérias resistentes a antibióticos, bem como a probabilidade de estes organismos chegarem até ao consumidor final, através da água da torneira. O estudo foi planeado para atingir esse objectivo, através do rastreio de comunidades bacterianas e de isolados individuais desde a captação até à torneira. Inicialmente, a abundância e diversidade bacteriana em água não-tratada, tratada e final (torneira) foi caracterizada através do uso de abordagens dependentes e independentes (16S rRNA-DGGE) de cultivo. Ambas as abordagens mostraram que o tratamento da água reduziu as contagens, a cultivabilidade e a diversidade bacteriana, promovendo também a alteração da comunidade bacteriana cultivável de predominantemente bactérias Gram-negativas para predominantemente Gram-positivas. No entanto, este efeito foi revertido, e na água de torneira as bactérias Gram-negativas voltaram a ser predominantes. Adicionalmente, na água de torneira as contagens de microrganismos totais e de bactérias cultiváveis foram mais elevadas do que para a água tratada recolhida no sistema de distribuição. Estes resultados sugerem a ocorrência de reactivação e crescimento bacteriano e/ou a formação de biofilme ao longo do sistema de distribuição e ao nível das torneiras. Apesar de se terem observado alterações na estrutura da comunidade bacteriana ao longo do circuito da água, o filo detetado como predominante, por 16S rRNA-DGGE, foi o mesmo em todos os pontos de amostragem – Proteobacteria (principalmente das classes Alpha, Beta e Gamma). Abordagens dependentes e independentes de cultivo foram comparadas para avaliar quais os grupos que poderão ser ignorados quando se caracterizam comunidades bacterianas usando métodos de cultivo. De forma a ter uma evidência mais clara dos grupos bacterianos que se sobrepõem usando as duas abordagens, o método dependente e dois independentes de cultivo (DGGE e pirosequenciação 454 com base no gene 16S rRNA) foram comparados quanto à sua capacidade para detectar a diversidade bacteriana de uma amostra de água. Esta comparação mostrou que apesar de os diferentes métodos identificarem o mesmo filo como sendo predominante, as bactérias detetadas eram diferentes. Assim, além da expectativa anterior de que os métodos independentes de cultivo detetassem mais grupos bacterianos do que os dependentes de cultivo, concluiu-se também que as duas abordagens incidem sobre diferentes populações bacterianas. Com base no estudo da diversidade bacteriana, principalmente das bactérias cultiváveis, e no que se encontra disponível na literatura, dois grupos taxonómicos de grande relevância em água de consumo, devido à sua ampla distribuição e/ou abundância, foram estudados. Assim, Sphingomonadaceae e Pseudomonas spp., isoladas desde a captação até à torneira foram caracterizadas para a diversidade de espécies, a variabilidade intra-espécie e o potencial para propagar resistências a antibióticos. Apesar de membros da mesma espécie terem sido identificados em diferentes locais, o mesmo genótipo nunca foi detetado na captação ou sistema de distribuição e em água de torneira. De acordo com estes resultados, a hipótese de que as bactérias detetadas em água de torneira teriam origem na água da captação teve de ser rejeitada. Contudo, este estudo conduz a outras hipóteses, nomeadamente a ocorrência de reactivação e crescimento microbiano nas canalizações ou torneiras, ou de uma contaminação externa, a jusante dos pontos amostrados no sistema de distribuição. Adicionalmente, a análise dos perfis de resistência a antibióticos confirmaram que tanto Sphingomonadaceae como Pseudomonas spp. são potenciais reservatórios de resistência a antibióticos. No entanto, este estudo não permitiu obter evidências claras da ocorrência de transferência horizontal de genes. Na verdade, os padrões de resistência a antibióticos relacionaram-se principalmente com a espécie e não com o local ou estirpe, sugerindo a importância da transmissão vertical de resistências em bactérias da água. Alguns fenótipos de resistência a antibióticos detectados em água de torneira não foram detetados a montante. São exemplos os fenótipos de resistência a ampicilina-sulbactame, piperacilina e tazobactam-piocianina, imipenemo, ceftazidima, gentamicina ou tobramicina nas Sphingomonadaceae, ou a estreptomicina e rifampicina nas Pseudomonas spp. Os métodos independentes de cultivo mostram invariavelmente que a maioria das bactérias de uma comunidade são desconhecidas, o que significa que nunca foram cultivadas, caracterizadas e integradas num grupo taxonómico validamente descrito. A taxonomia bacteriana pode ter um importante contributo para gradualmente se reduzir a parcela correspondente às bactérias desconhecidas. Neste estudo o novo nome Bacillus purgationiresistens sp. nov. foi proposto, com base num único isolado recuperado de água tratada. A água de consumo foi confirmada como potencial ponto-chave para a disseminação de bactérias resistentes a antibióticos, com destaque para a transferência ambiente-humanos