A metabolism perspective on alternative urban water servicing options using water mass balance

Urban areas will need to pursue new water servicing options to ensure local supply security. Decisions about how best to employ them are not straightforward due to multiple considerations and the potential for problem shifting among them. We hypothesise that urban water metabolism evaluation based a water mass balance can help address this, and explore the utility of this perspective and the new insights it provides about water servicing options. Using a water mass balance evaluation framework, which considers direct urban water flows (both ‘natural’ hydrological and ‘anthropogenic’ flows), as well as water-related energy, we evaluated how the use of alternative water sources (stormwater/rainwater harvesting, wastewater/greywater recycling) at different scales influences the ‘local water metabolism’ of a case study urban development. New indicators were devised to represent the water-related ‘resource efficiency’ and ‘hydrological performance’ of the urban area. The new insights gained were the extent to which alternative water supplies influence the water efficiency and hydrological performance of the urban area, and the potential energy trade-offs. The novel contribution is the development of new indicators of urban water resource performance that bring together considerations of both the ‘anthropogenic’ and ‘natural’ water cycles, and the interactions between them. These are used for the first time to test alternative water servicing scenarios, and to provide a new perspective to complement broader sustainability assessments of urban water

Evaluation approaches for advancing urban water goals

Urban areas (especially cities) are challenged in meeting their direct water needs from local sources. They also exert strain on global water resources through their indirect (virtual) water use. Agencies concerned with urban water management have visions and goals for managing direct water use, but indirect use is only inferred in more global visions for sustainable consumption. There is limited quantification of "urban water performance" at the macro urban scale (whole of city) to monitor progress toward these goals. It is constrained by a lack of clarity about the evaluation approaches that best serve them. We ask, How can the evaluation approaches described in literature advance urban water management goals? We reviewed the utility of eight evaluation approaches, including urban water system modeling, urban metabolism (territorial and mass balance), consumption (life cycle assessment, water footprinting, and input-output analysis), and complex systems (ecological network analysis and systems dynamics) approaches. We found that urban metabolism based on water mass balance is a core method for generating information to inform current goals for direct urban water use, with potential for being "coupled" with the other approaches. Consumption approaches inform the management of indirect water use. We describe this in a framework for urban water evaluation to give greater clarity to this field and flag the further research that would be needed to progress this. It includes the recommendation to differentiate the evaluation of direct and indirect urban water, but to also interpret them together

Liveability and its interpretation in urban water management: Systematic literature review

Liveability is a term widely used in literature, but there does not appear to be a consensus around its definition. This is a problem for the water management sector who are increasingly extending the articulation of their services to capture the liveability value of water in the urban landscape. Recognising that liveability is a dynamic and multi-dimensional concept, this paper seeks to explore the differences in meaning found in the literature and highlight the context that drives them. Specifically, we ask: How has academic scholarship and broader non-academic literature conceptualised liveability and how has it been interpreted in the context of urban water management? To answer this question we conducted a systematic review of academic and non-academic literature, identified attributes of liveability found therein, and looked for commonalities among different groups.The results show that conceptualisations of liveability differ between academic and non-academic literature but transport and connectedness emerge as central liveability themes in both. Interpretations of liveability within urban water management, on the other hand, focus primarily on the role of water in enhancing public greenspace often in the context of stormwater management and water governance.This paper contributes to the understanding of liveability, by identifying commonly used liveability attributes and discussing possible drivers of divergent conceptualisations of liveability: influence of policy, institutional logics of research, and growing interest in technical and engineering fields. We also discuss how distinct conceptualisation of liveability within urban water management can be attributed to the changes in water governance and its role in enhancing public greenspace. Collectively, this suggests that more critical understanding of liveability is needed - one which recognises the heterogeneity of different conceptualisations and the external and internal context that drives them

Bio-production from Australian sugarcane: An environmental investigation of product diversification in an agro-industry

This paper assesses the environmental impacts of producing bio-energy, bio-fuels and bio-materials from Australian sugarcane (Saccharum officinarum), and nominates the bio-production pathways offering the best environmental gains. A system-based, consequential approach was taken, which is different to past approaches that have commonly judged bio-production by comparing individual bio-products with their fossil-fuel counterparts. Possible diversified scenarios were developed, and the changes in environmental impacts from the system as a whole (per 100 t sugarcane processed) were assessed using life cycle assessment (LCA). Scenarios based on utilisation of co-products from existing sugarcane production (ethanol from molasses, and electricity and ethanol from surplus bagasse) were found to give modest reductions in non-renewable energy (NRE) use and global warming potential (GWP), and involve no or few trade-offs. Of these, ethanol and electricity from bagasse offer the best benefits. Scenarios necessitating expanded cane growing for dedicated production of ethanol and polylactide (PLA) plastics from cane juice were found to result in more substantial NRE and GWP savings, but involve the trade-offs associated with expanded agricultural production (land use, water use and potential water quality impacts). Of these, PLA production offers the better outcomes, amongst the scenarios. However, eco-efficient cane growing was found to be an equally important improvement strategy and should be implemented to enhance the benefits and mitigate some of the trade-off from bio-production.</p

Life cycle assessment of Australian sugarcane products with a focus on cane processing

Purpose This work generates attributional life cycle assessment (LCA) results for products produced from Australian sugarcane-raw sugar, molasses, electricity (from bagasse combustion), and ethanol (from molasses). It focuses on cane processing in sugar mills and is a companion to the work presented in (Renouf et al. 2010), where the focus is on cane growing. This work also examines the preferred approach for assigning impacts to the multiple products from cane processing, and the influence that variability in cane growing has on the results

Integrated urban water systems

Water plays a central role in creating sustainable cities. Past focus has been on centralised potable water supplies, wastewater treatment and drainage. However, focus is shifting towards localised fit-for purpose supplies, restoring natural water flows, minimising water-related energy, and achieving liveability through water. New conceptual frameworks help us understand this broader context. The urban water metabolism framework gives a big-picture perspective and comprehensive account of all water flows to generate water performance indicators. Quantification of the energy- and carbon-intensity of urban water (life cycle assessment and marginal abatement cost curves) helps identify the role of water management in decarbonising cities. Frameworks for understanding water-related liveability help us consider water efficiency in terms of the broader functions water delivers, instead of just per unit supplied

Site-scale Urban Water Mass Balance Assessment (SUWMBA) to quantify water performance of urban design-technology-environment configurations

Historically, little consideration has been given to water performance of urban developments such as “hydrological naturalness” or “local water self-sufficiency”. This has led to problems with increased stormwater runoff, flooding, and lack of local contributions to urban water security. Architectural design, water servicing technologies and environmental conditions are each known to influence water performance. However, most existing models have overlooked the integration of these factors. In this work, we asked ‘how the water performance of urban developments at site-scale can be quantified, with joint consideration of architectural design, water servicing technologies, and environmental context (i.e. climate and soil)’. Answering this question led to the development of a new method and tool called Site-scale Urban Water Mass Balance Assessment (SUWMBA). It uses a daily urban water mass balance to simulate design-technology-environment configurations. Key features include: (i) a three-dimensional boundary focussed on the “entity” of development (ii) a comprehensive water balance accounting for all urban water flows, (iii) methods that include key variables capturing the interactions of natural, built-environment and socio-technological systems on water performance. SUWMBA's capabilities were demonstrated through an evaluation of a residential infill development case study with alternative design-technology-environment configurations, combining three dwelling designs, seven water technologies and three environmental contexts. The evaluation showed how a configuration can be identified that strikes a balance between the conflicting objectives of achieving the desired dwelling densities whilst simultaneously improving water performance. For two climate zones, the optimal configuration increases the total number of residents by 300% while reducing the imported water per capita and stormwater discharge by 45% and 15%, respectively. We infer that SUWMBA could have strong potential to contribute to performance-based urban design and planning by enabling the water performance of dwelling designs to be quantified, and by facilitating the setting of locally-specific water performance objectives and targets

A review of the water-related energy consumption of the food system in nexus studies

This study reviewed nexus researches, synthesize and discuss insights, methodological practices, and future outlook of water-related energy consumption assessment of the food system. For the first time, the study assessed: (i) the trends and drivers of water-related energy research in different countries, (ii) how water-related energy in the food system is being evaluated (objectives & scale, study dimension & analysis focus, and methods) and (iii) the significance of food-system water-related energy in comparison with other sectors. Of 686 nexus studies undertaken since 1990, 104 studies (15%) quantified water-related energy. Studies have generally broadened in scope through time. The USA, China, and Australia have conducted most studies representing 23%, 17%, 15% of total respectively. A few of the identified major drivers in these countries leading water-related energy assessment are: providing optimal solutions and avoiding problem-shifting, analyzing the challenges and opportunities to reduce water-related energy, and exploring the energy-saving benefits by saving water. Of the 104 water-related energy studies, 65 articles (∼60%) related to the food system, focussed on the agriculture phase for irrigation energy consumption. Existing nexus studies often ignored other phases such as food processing and cooking, which are more energy-intensive. Over 50% of studies used material flow analysis to evaluate water-related energy in the food system. Few of the nexus studies evaluated inter-regional flows or changes through time. Absence of a comprehensive study of the entire food system, and wide variations in study system boundary and definitions, make it difficult to compare sectoral significance. However, the order of sectoral water-related energy consumption (from highest to lowest) identified as industrial, residential, agriculture, and water and wastewater service. Our review demonstrates a tremendous opportunity and need for an overarching framework to enable systematic evaluation and benchmarking of water-related energy consumption of the food system

Urban water metabolism information for planning water sensitive city-regions

Climate change and growing populations will stretch water resources in many city-regions globally, and urbanisation will continue to degrade water quality and upset natural hydrological flows. These pressures call for alternative urban water management approaches with improved connection with land use planning. Evaluating the water metabolism of urban areas gives a holistic picture of how water flows through and is transformed by urban settlements, to inform land use planning for sustainably managing urban water. Previous research has conceptualised how metabolism science may inform urban land use planning. In this work, we build on to identify how urban water metabolism evaluations can inform urban planning practice. We ask, ‘how can urban water metabolism evaluations support urban and water planning towards water sensitive city-regions?’ Focusing on three Australian capital city-regions, we empirically identify the knowledge needs of practitioners and compare this against the knowledge known to be generated from past urban water metabolism evaluations. This was done within a framework of urban water resource management objectives for water sensitive cities - that is, protection of water resources and hydrological flows, recognition of the diverse functions of water, and resource efficiency and supply internalisation. Based on the findings, the paper discusses five key strategic initiatives for planning for water sensitive city-regions: resource efficiency and hydrological performance benchmarks and targets for urban developments, tailoring programmes for resource efficiency, making case for regional blue-green space networks for improved hydrological performance, small and large-scale infrastructure innovation, and social and institutional innovation in urban water management