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

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

Scenario 2040 for Oslo as model city

This report – D34.2, authored by NTNU, is a sequel to D34.1 in which interventions suggested by the water-sanitation utility in Oslo - Oslo Vann og Avløpsetaten, had been tested using both the models – the WaterMet 2 (WM2) model developed by Exeter and the Dynamic Metabolism Model (DMM) developed at NTNU, as part of TRUST. The report starts off by emphasising the need for a holistic long-term sustainability approach in decision-making in water and wastewater utilities around the world. The models referred to above, are proposed as aids in meeting this need. With the help of references to earlier published works and TRUST deliverables related to these models, as well as some new tests carried out using one of them (DMM), the usability of the same has been demonstrated. ‘Usability’ here refers to understanding the impact of interventions on selected metrics/indicators in year-2040 (in keeping with the title of the deliverable; and the timeframe which has been considered for the TRUST project); and subsequent choices/selections which utilities would like to make depending on their priorities, targets and benchmarks they would set for themselves. As concluded in D34.1, there are differences between WM2 and DMM – which make them useful in different contexts – situational, circumstantial etc. These differences are recounted here again, in order to make it clear to the readers and end-users that one model is not meant to substitute the other, per se. Simply put, depending on what the end-users’ needs, goals, objectives and constraints are, one or the other would be preferable. The models have been extensively tested at Oslo VAV. A brief summary of the initial feedback from personnel at Oslo VAV is provided. The models were also introduced to pilot cities to understand their points of view, which have been presented in brief.Venkatesh, G.; Sægrov, S.; Brattebø, H. (2014). Scenario 2040 for Oslo as model city. http://hdl.handle.net/10251/4662

Urban water system metabolism assessment using WaterMet2 model

This paper presents a new “WaterMet2” model for integrated modelling of an urban water system (UWS). The model is able to quantify the principal water flows and other main fluxes in the UWS. The UWS in WaterMet2 is characterised using four different spatial scales (indoor area, local area, subcatchment and system area) and a daily temporal resolution. The main subsystems in WaterMet2 include water supply, water demand, wastewater and cyclic water recovery. The WaterMet2 is demonstrated here through modelling of the urban water system of Oslo city in Norway. Given a fast population growth, WaterMet2 analyses a range of alternative intervention strategies including ‘business as usual’, addition of new water resources, increased rehabilitation rates and water demand schemes to improve the performance of the Oslo UWS. The resulting five intervention strategies were compared with respect to some major UWS performance profiles quantified by the WaterMet2 model and expert's opinions. The results demonstrate how an integrated modelling approach can assist planners in defining abetter intervention strategy in the future

Quantitative UWS performance model: WaterMet2

The WaterMet2 tool encapsulates a conceptual, mass balance based model that enables quantifying the performance of an integrated urban water system (UWS) over a prolonged period of time (typically years) with a daily time step. The model allows quantifying the UWS performance, both water quantity and quality related, at different spatial scales and with particular focus on sustainability related performance. The WaterMet2 covers the full urban water cycle and provides means of evaluating the impact of different potential intervention strategies in the context of strategic level, long-term future decision making. It also provides basis for the assessment of various risks associated with the UWS performance.Behzadian, K.; Kapelan, Z.; Govindarajan, V.; Brattebø, H.; Sægrov, S.; Rozos, E.; Makropoulos, C. (2014). Quantitative UWS performance model: WaterMet2. http://hdl.handle.net/10251/4662

Using the multiple scenario approach for envisioning plausible futures in long-term planning and management of the urban water pipe systems

Abstract Water utilities are facing the challenging problem of planning rehabilitation and renewal of their urban water systems for an uncertain future, which will be affected by climate change, demographic changes and extensive changes in the way the public perceives the water services. For the purpose of envisioning the future, the multiple scenario approach is presented, and its benefits and drawbacks are discussed in relation to other futures forecasting methods. The paper guides the reader on how to build scenarios that represent plausible futures for renewal planning of urban water and wastewater networks. For this purpose, a table is produced that gives an overview of relevant scenarios and their potential consequences. In the end, a case study from a Norwegian perspective is presented that gives the reader an overview of the process of building scenarios based on both qualitative and quantitative approaches

Detection of extraneous water ingress into the sewer system using tandem methods- A case study in Trondheim city

Infiltration and inflow (I/I) of extraneous water in separate sewer systems are serious concerns in urban water management for their environmental, social and economic consequences. Effective reduction of I/I requires knowing where excess water ingress and illicit connections are located. The present study focuses on I/I detection in the foul sewer network of a catchment in Trondheim, Norway, during a period without snowmelt or groundwater infiltration. Fiber-optic distributed temperature sensing (DTS) was used for the first time in Norway to detect I/I sources in tandem with closed-circuit television inspection (CCTV) and smoke testing. DTS was an accurate and feasible method for I/I detection, though it cannot identify exact types of failure and sources of I/I. Therefore, other complementary methods must be used, e.g. CCTV or smoke testing. However, CCTV was not completely useful in confirming the DTS results. This study provides practical insights for the rehabilitation and repair of sewer networks that suffer from the undesirable I/I of extraneous water

Quantification Assessment of Extraneous Water Infiltration and Inflow by Analysis of the Thermal Behavior of the Sewer Network

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

An Analysis of the Potential Impact of Climate Change on the Structural Reliability of Drinking Water Pipes in Cold Climate Regions

The climate is changing worldwide. For the northern hemisphere there are distinct challenges related to climate change. It is expected that temperature on a general basis will increase within the next 100 years, and that the increase will be most severe during winter months. The literature shows a correlation between temperature and failures. This correlation is most evident for smaller grey cast iron pipes, and for pipes which is constructed in trenches vulnerable to frost heave. A comprehensive amount of failure data (over 25,000 failures) has been gathered from Norwegian cities in order to quantify the correlation between temperatures and failure rates. The analysis supports the findings in the literature, by establishing a statistical significant correlation, which states that failure rates increase with falling temperatures. At the same time, the expected increase in future temperatures has been used to analyze the impact on failure rates within 2070. The results show that the increasing temperatures will have a positive effect on failure rates. It can be expected that failure rates will be reduced by 2.7% to 7.2% within 2070, depending on the climate scenario

Infrastructure Asset Management: Historic and Future Perspective for Tools, Risk Assessment, and Digitalization for Competence Building

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.publishedVersio