A Qualitative and Quantitative Assessment of the Long-Term Hydraulic Reliability of Norwegian Water Distribution Network - A Case Study
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AbstractToday, the water utilities in Norway experience ageing and deterioration of assets in their water supply systems. The rehabilitation rate needs to increase in order to avoid a possible lag in renewal. Trends of population growth and climate change, cause impacts to the reliability of the water distribution service, with uncertainty. It is therefore a need to assess such future trends, their impact to the service delivered and to select adaptive and corrective measure to ensure the right level of service. This master thesis presents how the external factors mentioned above; population growth, climate change and asset deterioration, impact water supply systems in a longer time horizon. Such uncertainties are studied in a comprehensive literature review. Additionally, a qualitative assessment on future expectations of the water supply level of service is collected. This has been done by interviews of both social researchers from NTNU, and of local experts from four different water utilities. The literature review and qualitative assessment, forms the basis for the establishment of possible future scenarios in a water system. These scenarios have been interacted with local circumstances in a selected case network. The different scenarios have been simulated in a hydraulic model called WDNetXL. The hydraulic reliability of the different scenarios has been assessed, in regard to the whole system reliability and nodal reliability. The results from the literature review and the qualitative approach show that the climate change deteriorate the assets within a water distribution network, and thus a reduction in reliability. New and modified digital devices for effective monitoring should be used with care, in order to avoid eventually operational failures within a water supply network. The results from the case study shows that the studied system is reliable in all simulated future scenarios. However, the nodal reliability is reduced in some hydraulic sensitive areas within the case network. The population growth, and thus increase in water demand, has the biggest impact one the hydraulic performance of the studied factors. Other factors, which have been study with simulations, are leakage and possible increase in pipe roughness. The information included are subject to confidential agreement between NTNU and the water utility of Oslo (Oslo VAV). Please treat this document as strictly confidential.