Modelling metabolism based performance of an urban water system using WaterMet2

This paper presents a new quantitative model called 'WaterMet(2)' for the metabolism based assessment of the integrated urban water system (UWS) performance. WaterMet(2) quantifies a number of UWS flows/fluxes (e.g. water and energy) which can be used to derive sustainability-based performance metrics. The generic WaterMet(2) model overcomes the drawbacks of the existing UWS models and strives to bridge the gaps related to the nexus of water, energy and other environmental impacts in an integrated UWS. The main features of WaterMet(2) are: (1) conceptual simulation model of UWS comprised of water supply, stormwater and wastewater subsystems with possible centralised and decentralised water reuse; (2) UWS represented by an arbitrary number of key UWS components for each type in four spatial scales (System, Subcatchment, Local and Indoor areas) in a distributed modelling type approach; (3) quantifying the metabolism-based performance of UWS including the caused and avoided environmental impact categories (GHG emissions, acidification and eutrophication potentials) and resource recovery in UWS. WaterMet(2) is tested, validated and demonstrated by evaluating the long-term performance of the UWS of a northern European city for three states including business as usual and two intervention strategies: addition of new water resources and large scale localised water recycling. The results obtained demonstrate the effectiveness of WaterMet(2) in evaluating the sustainability related UWS performance, the suitability of using WaterMet(2) at the strategic level UWS planning and the importance of using an integrated assessment approach covering the full urban water cycle. (C) 2015 Elsevier B.V. All rights reserved.