Decision support system for the long-term city metabolism planning problem

A Decision Support System (DSS) tool for the assessment of intervention strategies (Alternatives) in an Urban Water System (UWS) with an integral simulation model called “WaterMet²” is presented. The DSS permits the user to identify one or more optimal Alternatives over a fixed long-term planning horizon using performance metrics mapped to the TRUST sustainability criteria (Alegre et al., 2012). The DSS exposes lists of in-built intervention options and system performance metrics for the user to compose new Alternatives. The quantitative metrics are calculated by the WaterMet² model and further qualitative or user-defined metrics may be specified by the user or by external tools feeding into the DSS. A Multi-Criteria Decision Analysis (MCDA) approach is employed within the DSS to compare the defined Alternatives and to rank them with respect to a pre-specified weighting scheme for different Scenarios. Two rich, interactive Graphical User Interfaces, one desktop and one web-based, are employed to assist with guiding the end user through the stages of defining the problem, evaluating and ranking Alternatives. This mechanism provides a useful tool for decision makers to compare different strategies for the planning of UWS with respect to multiple Scenarios. The efficacy of the DSS is demonstrated on a northern European case study inspired by a real-life urban water system for a mixture of quantitative and qualitative criteria. The results demonstrate how the DSS, integrated with an UWS modelling approach, can be used to assist planners in meeting their long-term, strategic level sustainability objectives

Assessing Integrated Water Management Options for Urban Developments - Canberra case study

Urban water services in the Australian Capital Territory (ACT) are currently provided through conventional centralised systems, involving large scale water distribution, wastewater collection, water and wastewater treatment. A study was conducted to assist Environment ACT in setting broad policies for future water services in Canberra. This paper presents the outcomes of a study examining the effects of various water servicing options on water resources and the environment, for two townships in Canberra, one existing and one greenfield site. Three modelling tools were used to predict the effects of various alternative water servicing scenarios, including demand management options, rainwater tanks, greywater use, on-site detention tanks, gross pollutant traps, swales and ponds. The results show that potable water reductions are best achieved by demand management tools or a combination of greywater and rainwater use for existing suburbs, while 3rd pipe systems are preferred for greenfield sites. For this specific climatic region and end use demands, modelling predicted increased water savings from raintanks compared to greywater systems alone, with raintanks providing the additional benefit of reduced peak stormwater flows at the allotment scale. Rainwater and stormwater reuse from stormwater ponds within the catchments was found to provide the highest reduction in nutrient discharge from the case study areas. Environment ACT amended planning controls to facilitate installation of raintanks and greywater systems, and commenced a Government funded rebate scheme for raintanks as a result of this study

The Urban Water Cycle in Bogotá, Colombia: Current Status and Challenges for Sustainability

Conocer los componentes y el comportamiento del ciclo urbano del agua permite gestionar de manera adecuada los recursos ambientales y económicos de una ciudad, pues este concepto integra elementos hidrológicos, hídricos, de abastecimiento, de distribución, uso del agua, de recolección, tratamiento y reutilización. En Bogotá, las tasas de crecimiento poblacional y geográfico aumentan de manera acelerada, a tal punto que el ciclo urbano del agua cada vez adquiere mayor importancia para administraciones públicas, privadas y para los habitantes debido a la búsqueda de fuentes de abastecimiento, a la ampliación de la infraestructura de saneamiento básico y al aporte de contaminantes a ríos. Con base en lo anterior, este artículo ofrece un diagnóstico del estado actual de los componentes del ciclo urbano del agua en Bogotá, además presenta diferentes retos que tiene la ciudad para un futuro ambiental, social y económico sostenible.Understand the components and the behavior of the Urban Water Cycle is useful to management the environmental and economic resources of a city. This concept integrates hydrological, water supply, distribution, water use, water pollution, harvesting, treatment and reuse. In Bogotá the rates of population and geographic growth are going to accelerated pace, to the point that the urban water cycle is gaining greater importance in public and private administrations, because is necessary search new sources of water supply, extension of basic sanitation infrastructure and the control of pollutants in Bogotá’s rivers. According to the above, this paper presents an analysis of the current state of the components of the urban water cycle in Bogotá, additionally presents different challenges facing the city for sustainable environmental, social and economic future

Urban water modelling and the daily time step: issues for a realistic representation

Interest in modelling the total Urban Water Cycle is increasing, due to the realisation of the need for (high-level) flow integration to address issues of recycling, re-use and ultimately sustainability. Urban Water Cycle models are generally operating on a daily time step due to the inherent strategic/planning nature of such work. However, the choice of time step implies (more or less hidden) assumptions which may influence significantly the model’s performance. One such assumption – the way in which water tanks (e.g. rainwater, greywater, greenwater etc) are operated in terms of the sequence between tank overflow (spill) and water extracted from the tank for use (yield) is investigated in this paper. The two alternative sequences are termed here Yield After Spill (YAS) and Yield Before Spill (YBS). The Urban Water Optioneering Tool was used and advantages and disadvantages of these sequences were examined. The paper reviews the differences under a series of technological configurations and draws recommendations for modelling practice. It is suggested that YAS/YBS schemes have different impacts depending on the technological configuration of the case study under investigation, but that under normal operating conditions, daily time step simulations with YBS schemes tend to result in tank sizes that are (marginally) closer to sizes obtained by hourly time-steps. It is however suggested that YAS schemes should be preferred when the parameter of interest is runoff

Decision Support System for the Long-Term City Metabolism Planning Problem

AcceptedArticleA Decision Support System (DSS) tool for the assessment of intervention strategies (Alternatives) in an Urban Water System (UWS) with an integral simulation model called “WaterMet2” is presented. The DSS permits the user to identify one or more optimal Alternatives over a fixed long-term planning horizon using performance metrics mapped to the TRUST sustainability criteria (Alegre et al., 2012). The DSS exposes lists of in-built intervention options and system performance metrics for the user to compose new Alternatives. The quantitative metrics are calculated by the WaterMet2 model and further qualitative or user-defined metrics may be specified by the user or by external tools feeding into the DSS. A Multi-Criteria Decision Analysis (MCDA) approach is employed within the DSS to compare the defined Alternatives and to rank them with respect to a pre-specified weighting scheme for different Scenarios. Two rich, interactive Graphical User Interfaces, one desktop and one web-based, are employed to assist with guiding the end user through the stages of defining the problem, evaluating and ranking Alternatives. This mechanism provides a useful tool for decision makers to compare different strategies for the planning of UWS with respect to multiple Scenarios. The efficacy of the DSS is demonstrated on a northern European case study inspired by a real-life urban water system for a mixture of quantitative and qualitative criteria. The results demonstrate how the DSS, integrated with an UWS modelling approach, can be used to assist planners in meeting their long-term, strategic level sustainability objectives.EU 7th Framework Programm

Water Use and Urban Agriculture: Estimation and Water Saving Scenarios for Residential Kitchen Gardens

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CSIRO Marine and Atmospheric Research, 2

With over 84 % of Australians living in urban areas (populations over 30,000), the outcome of the current debate on water use in cities and how to match water demand to supply under both current and future climates, has the potential to affect many Australians. Lacking in this debate is a sound quantitative basis for assessing the environmental and economic benefits of water use in urban areas. As an example, while water sensitive urban design (WSUD) is widely accepted as a tool to manage the impacts of urbanisation by careful design at the house and street scale, its focus has largely been on managing and re-using the runoff (stormwater and wastewater) component of the water balance. Much less attention has been paid to the role of urban evapotranspiration (ET) by urban hydrologists, even though this it is often the biggest output in the water balance. Evapotranspiration is the process that links the movement of water through a landscape with the local climate, with the process using energy that would otherwise contribute to elevated air temperatures. This passive control of the local climate via urban vegetation and ET has a direct influence on quantities of energy used in space heating and cooling through the role of urban ET and also because trees provide shade and shelter. This link between the urban water and energy balances, and microclimate, is demonstrated by considering the following simplified expressions for i) the urban water balance: P+ I = ET + D+ΔS (1) where the inputs are: P = precipitation; I = piped water supply (for external and internal uses); and the outputs are: ET = urban evapotranspiration; D = stormwater and wastewater; ΔS = change in stored water on and within the surface materials; and ii) the urban energy balance: Q + QF = QH + QE +ΔQ

Direct Simulation of Micro-Component Water Consumption for the Evaluation of Potential Water Reuse in Households

A study on water/energy balances at the household scale is performed using Life Cycle Assessment (LCA) to estimate Greenhouse Gas (GHG) emissions and impacts resulting from multiple scenarios incorporating various options for: (i) component sizing, (ii) energy usage, and (iii) water reuse. Sustainability indicators are evaluated to select feasible options, while reducing whole life cycle GHG emissions. Water reuse schemes using rainwater are strongly dependent on rainfall availability and require significant tank volumes. Schemes using only gray water are more compact but more energy for treatment is needed before usage. Schemes obtained by combining both options perform better in terms of reliability and sustainability

WaterMet2: a tool for integrated analysis of sustainability-based performance of urban water systems

Open Access journalThis paper presents the "WaterMet2" model for long-term assessment of urban water system (UWS) performance which will be used for strategic planning of the integrated UWS. WaterMet2 quantifies the principal water-related flows and other metabolism-based fluxes in the UWS such as materials, chemicals, energy and greenhouse gas emissions. The suggested model is demonstrated through sustainability-based assessment of an integrated real-life UWS for a daily time-step over a 30-year planning horizon. The integrated UWS modelled by WaterMet2 includes both water supply and wastewater systems. Given a rapid population growth, WaterMet2 calculates six quantitative sustainability-based indicators of the UWS. The result of the water supply reliability (94%) shows the need for appropriate intervention options over the planning horizon. Five intervention strategies are analysed in WaterMet2 and their quantified performance is compared with respect to the criteria. Multi-criteria decision analysis is then used to rank the intervention strategies based on different weights from the involved stakeholders' perspectives. The results demonstrate that the best and robust strategies are those which improve the performance of both water supply and wastewater systems.European Union Seventh Framework Programme (FP7/2007-2013