Infiltration and inflow (I/I) of unwanted water in separate urban sewer networks are critical issues for sustainable urban water management. Accurate quantification of unwanted water I/I from individual sources into a sewer system is an essential task for assessing the status of the sewer network and conducting rehabilitation measures. The study aim was to quantify extraneous water I/I into a sanitary sewer network by a temperature-based method, i.e., fiber-optic distributed temperature sensing (DTS), which was applied for the first time in a separate sewer network of a catchment in Trondheim, Norway. The DTS technology is a relatively new technology for sewer monitoring, developed over the past decade. It is based on continual temperature measurement along a fiber-optic cable installed in the sewer network. The feasibility of this method has been tested in both experimental discharges and for the rainfall-derived I/I. The results achieved from the monitoring campaign established the promising applicability of the DTS technique in the quantification analysis. Furthermore, the application of this method in quantifying real-life, rainfall-derived I/I into the sewer system was demonstrated and verified during wet weather conditions.

This article aims at analyzing the historic development of infrastructure asset management (IAM) resulting from the increase of challenges over time. Furthermore, it aims at suggesting the corresponding requirements for the enrichment of educational programs to provide the decision makers of tomorrow with the right competences. The evolution of IAM is here described as characterized by three periods introducing an increased complexity of analysis and thereby, a more powerful system for urban water management: (a) Data collection and development of computerized information systems including statistical methods for information management; (b) application of risk analysis including sources of hazards and their consequences; and (c) introduction of a holistic sustainable perspective including governance, social and economic aspects (circular economy), environmental impacts, and the condition of physical assets including digital systems. A variety of competencies are needed to obtain the safe management of urban water systems, in particular for the provision of water services in medium- and large-scale cities. Similar competencies are needed for other infrastructures, like buildings, roads and railroads, and IT systems. The elements of sustainability including risk assessment and digitalization should be incorporated in master programs for civil engineering world-wide. This paper is not designed as a scientific paper, but as inspirational for IAM practitioners and for the development of enriched educational programs of technical universities.

This 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.

It is generally difficult to assess the performance of an infrastructure with a substantially longer life span than economic models can handle, and the life cycle concepts in urban water systems are normally limited to single-asset projects. In order to explore the long-term impact of urban water infrastructure rehabilitation strategies, a life cycle approach for survival functions is suggested. A life cycle factor based on survival functions is introduced, which is a measuring value of the total expected service life of all pipes within a group of pipes. Another factor, termed the sustainability factor, is based on the relationship between the life cycle factor and a rehabilitation reference method, which makes it possible to correct the long-term performance of rehabilitation methods based on their expected service life provision. A case study presents the implications for investments in infrastructure rehabilitation when applying the sustainability factor in long-term planning, and shows the importance of considering the service life of rehabilitation methods when planning renewal interventions that minimize costs over their life cycles.

This paper presents the new "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, greenhouse gas emissions. The suggested model is demonstrated through sustainability-based assessment of an integrated UWS of Oslo city for daily time step over a 30 yr planning horizon. The integrated UWS modelled by WaterMet2 includes both water supply and wastewater systems. Given a fast 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 are 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 the best and robust strategies are those which improve the performance of both water supply and wastewater systems.