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Integrated urban water systems (IUWSs) generally comprise the components related to both water supply and waste water systems. These components are subject to uncertainty in terms of operation, management and information. Hence, assessment of strategies in the IUWSs over the planning horizon should include such a risk analysis of these uncertainties. Owning to the complexity of these risks, a comprehensive risk assessment tool needs to be developed. In this paper, a risk assessment tool is presented to support the evaluation of intervention strategies in an IUWS over a planning horizon. The IUWS is modelled by “WaterMet2” which is a simulation, deterministic and quantitative IUWS model and is able to quantify the principal water flows and other main fluxes in the IUWS. Risk assessment tool is connected to WaterMet2 model to analyse risk based criteria in the IUWS model. The developed approach is demonstrated through its application to the assessment of the intervention strategies for the IUWS of Oslo city in Norway over a 30-year planning horizon. The intervention strategies analysed here include 'business as usual', addition of new water resources, increased rehabilitation rates and a number of water demand schemes to improve the performance of the Oslo UWS. The assessment criteria are split into two categories of risk based and non-risk based criteria. The former is quantified by the WaterMet2 model whilst the latter is quantified by risk assessment tool. This tool recognises the relevant likelihood of occurrence for a risk in a component. The severity of impact of the risk is quantified by multiple WaterMet2 runs. The results, when compared to those without risk assessment criteria, show how much preferences the analysis can envisage once risk is involved in the assessment. This would help planners to make more robust decisions for the future of IUWSs.


Session R42, Risk and Uncertainty in Modeling Applications I



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