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We explore the dynamics of centralised and decentralised wastewater infrastructure across various scenarios and introduce novel insights into their performance regarding structural vulnerability, hydraulic capacity, and costs. This study determines circumstances under which infrastructure hybridisation outperforms traditional centralised infrastructure paradigms. We combined system analysis to map out the modelling problem with the model-based exploration of the transition space using the novel TURN-Sewers model. System diagramming was used to identify the parameters or combinations of parameters that significantly influence the performance indicators being assessed. This allowed the creation of relevant simulation scenarios to identify circumstances where a decentralised sewer system could outperform a centralised one. TURN-Sewers was applied to model the infrastructure maintenance and generation of new infrastructure over 20 years for a municipality on the Swiss Plateau, considering a population growth rate of 0.03 a−1. Results show that decentralisation in expansion areas with higher densification can outperform the hydraulic performance and structural vulnerability of expanding centralised sanitary wastewater infrastructure. Decentralised systems can also offer economic advantages when capital expenditure costs for small-scale wastewater treatment plants are significantly reduced compared to current costs, particularly at higher discount rates, e.g. reaping effects of economies of scale. The findings of this study emphasise the potential of transition pathways towards decentralisation in urban water infrastructures and the value of models that allow the exploration of this transition space., Policy Analysis

Future climatic, demographic, technological, urban and socio-economic challenges call for more flexible and sustainable wastewater infrastructure systems. Exploratory modelling can help to investigate the consequences of these developments on the infrastructure. In order to explore large numbers of adaptation strategies, we need to re-balance the degree of realism of sewer network and ability to reflect key performance characteristics against the model's parsimony and computational efficiency. We present a spatially explicit algorithm for creating sanitary sewer networks that realistically represent key characteristics of a real system. Basic topographic, demographic and urban characteristics are abstracted into a squared grid of ‘Blocks’ which are the foundation for the sewer network's topology delineation. We compare three different pipe dimensioning approaches and found a good balance between detail and computational efficiency. With a basic hydraulic performance assessment, we demonstrate that we attain a computationally efficient and high-fidelity wastewater sewer network with adequate hydraulic performance. A spatial resolution of 250 m Block size in combination with a sequential Pipe-by-Pipe (PBP) design algorithm provides a sound trade-off between computational time and fidelity of relevant structural and hydraulic properties for exploratory modelling. We can generate a simplified sewer network (both topology and hydraulic design) in 18 s using PBP, versus 36 min using a highly detailed model or 1 s using a highly abstract model. Moreover, this simplification can cut up to 1/10th to 1/50th the computational time for the hydraulic simulations depending on the routing method implemented. We anticipate our model to be a starting point for sophisticated exploratory modelling into possible infrastructure adaptation measures of topological and loading changes of sewer systems for long-term planning., Policy Analysis, Sanitary Engineering

Urban water management (UWM) is a complex problem characterized by multiple alternatives, conflicting objectives, and multiple uncertainties about key drivers like climate change, population growth, and increasing urbanization. Serious games are becoming a popular means to support decision-makers who are responsible for the planning and management of urban water systems. This is evident in the increasing number of articles about serious games in recent years. However, the effectiveness of these games in improving decision-making and the quality of their design and evaluation approaches remains unclear. To understand this better, in this paper, we identified 41 serious games covering the urban water cycle. Of these games, 15 were shortlisted for a detailed review. By using common rational decision-making and game design phases from literature, we evaluated and mapped how the shortlisted games contribute to these phases. Our research shows that current serious game applications have multiple limitations: lack of focus on executing the initial phases of decision-making, limited use of storytelling and adaptive game elements, use of low-quality evaluation design and explicit indicators to measure game outcomes, and lastly, lack of attention to cognitive processes of players playing the game. Addressing these limitations is critical for advancing purposeful game design supporting UWM., Sanitary Engineering, Policy Analysis

Freshwater resources in coastal areas are under intense pressure from excessive groundwater extraction, which amplifies saltwater intrusion (SWI) into coastal freshwater aquifers, such as in the Mekong Delta. Studies that combine socioenvironmental data and households' psychological factors next to salinity measurement data to design groundwater conservation strategies are rare. In this study, these aspects are combined to explore their influence on the public willingness to conserve groundwater using a Bayesian belief network model. We analyzed 313 household survey data spread over three districts in the coastal province of Tra Vinh, located in the Vietnamese Mekong Delta. The level of salinity is significantly correlated with the willingness to conserve groundwater. The top three socioenvironmental characteristics that influence willingness are the level of salinity, type of employment - i.e., being a farmer - and frequency of being exposed to groundwater or SWI promotional activities. Social norm, i.e., perceived social pressure, is the most influential psychological factor that determines willingness. This study reveals an urgency for the local government to intervene and create social pressure regarding the issue., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Sanitary Engineering, Policy Analysis, Water Resources

Freshwater resources in coastal areas are under intense pressure from excessive groundwater extraction, which amplifies saltwater intrusion (SWI) into coastal freshwater aquifers, such as in the Mekong Delta. Studies that combine socioenvironmental data and households' psychological factors next to salinity measurement data to design groundwater conservation strategies are rare. In this study, these aspects are combined to explore their influence on the public willingness to conserve groundwater using a Bayesian belief network model. We analyzed 313 household survey data spread over three districts in the coastal province of Tra Vinh, located in the Vietnamese Mekong Delta. The level of salinity is significantly correlated with the willingness to conserve groundwater. The top three socioenvironmental characteristics that influence willingness are the level of salinity, type of employment - i.e., being a farmer - and frequency of being exposed to groundwater or SWI promotional activities. Social norm, i.e., perceived social pressure, is the most influential psychological factor that determines willingness. This study reveals an urgency for the local government to intervene and create social pressure regarding the issue., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Sanitary Engineering, Policy Analysis, Water Resources

Urban water management (UWM) is a complex problem characterized by multiple alternatives, conflicting objectives, and multiple uncertainties about key drivers like climate change, population growth, and increasing urbanization. Serious games are becoming a popular means to support decision-makers who are responsible for the planning and management of urban water systems. This is evident in the increasing number of articles about serious games in recent years. However, the effectiveness of these games in improving decision-making and the quality of their design and evaluation approaches remains unclear. To understand this better, in this paper, we identified 41 serious games covering the urban water cycle. Of these games, 15 were shortlisted for a detailed review. By using common rational decision-making and game design phases from literature, we evaluated and mapped how the shortlisted games contribute to these phases. Our research shows that current serious game applications have multiple limitations: lack of focus on executing the initial phases of decision-making, limited use of storytelling and adaptive game elements, use of low-quality evaluation design and explicit indicators to measure game outcomes, and lastly, lack of attention to cognitive processes of players playing the game. Addressing these limitations is critical for advancing purposeful game design supporting UWM., Sanitary Engineering, Policy Analysis

Future climatic, demographic, technological, urban and socio-economic challenges call for more flexible and sustainable wastewater infrastructure systems. Exploratory modelling can help to investigate the consequences of these developments on the infrastructure. In order to explore large numbers of adaptation strategies, we need to re-balance the degree of realism of sewer network and ability to reflect key performance characteristics against the model's parsimony and computational efficiency. We present a spatially explicit algorithm for creating sanitary sewer networks that realistically represent key characteristics of a real system. Basic topographic, demographic and urban characteristics are abstracted into a squared grid of ‘Blocks’ which are the foundation for the sewer network's topology delineation. We compare three different pipe dimensioning approaches and found a good balance between detail and computational efficiency. With a basic hydraulic performance assessment, we demonstrate that we attain a computationally efficient and high-fidelity wastewater sewer network with adequate hydraulic performance. A spatial resolution of 250 m Block size in combination with a sequential Pipe-by-Pipe (PBP) design algorithm provides a sound trade-off between computational time and fidelity of relevant structural and hydraulic properties for exploratory modelling. We can generate a simplified sewer network (both topology and hydraulic design) in 18 s using PBP, versus 36 min using a highly detailed model or 1 s using a highly abstract model. Moreover, this simplification can cut up to 1/10th to 1/50th the computational time for the hydraulic simulations depending on the routing method implemented. We anticipate our model to be a starting point for sophisticated exploratory modelling into possible infrastructure adaptation measures of topological and loading changes of sewer systems for long-term planning., Policy Analysis, Sanitary Engineering

While the burden of disease from well-studied drinking water contaminants is declining, risks from emerging chemical and microbial contaminants arise because of social, technological, demographic and climatological developments. At present, emerging chemical and microbial drinking water contaminants are not assessed in a systematic way, but reactively and incidence based. Furthermore, they are assessed separately despite similar pollution sources. As a result, risks might be addressed ineffectively. Integrated risk assessment approaches are thus needed that elucidate the uncertainties in the risk evaluation of emerging drinking water contaminants, while considering risk assessors’ values. This study therefore aimed to (1) construct an assessment hierarchy for the integrated evaluation of the potential risks from emerging chemical and microbial contaminants in drinking water and (2) develop a decision support tool, based on the agreed assessment hierarchy, to quantify (uncertain) risk scores. A multi-actor approach was used to construct the assessment hierarchy, involving chemical and microbial risk assessors, drinking water experts and members of responsible authorities. The concept of value- focused thinking was applied to guide the problem-structuring and model-building process. The development of the decision support tool was done using Decisi-o-rama, an open-source Python library. With the developed decision support tool (uncertain) risk scores can be calculated for emerging chemical and microbial drinking water contaminants, which can be used for the evidence-based prioritisation of actions on emerging chemical and microbial drinking water risks. The decision support tool improves existing prioritisation approaches as it combines uncertain indicator levels with a multi-stakeholder approach and integrated the risk assessment of chemical and microbial contaminants. By applying the concept of value-focused thinking, this study addressed difficulties in evidence-ba, Sanitary Engineering, Policy Analysis

While the burden of disease from well-studied drinking water contaminants is declining, risks from emerging chemical and microbial contaminants arise because of social, technological, demographic and climatological developments. At present, emerging chemical and microbial drinking water contaminants are not assessed in a systematic way, but reactively and incidence based. Furthermore, they are assessed separately despite similar pollution sources. As a result, risks might be addressed ineffectively. Integrated risk assessment approaches are thus needed that elucidate the uncertainties in the risk evaluation of emerging drinking water contaminants, while considering risk assessors’ values. This study therefore aimed to (1) construct an assessment hierarchy for the integrated evaluation of the potential risks from emerging chemical and microbial contaminants in drinking water and (2) develop a decision support tool, based on the agreed assessment hierarchy, to quantify (uncertain) risk scores. A multi-actor approach was used to construct the assessment hierarchy, involving chemical and microbial risk assessors, drinking water experts and members of responsible authorities. The concept of value- focused thinking was applied to guide the problem-structuring and model-building process. The development of the decision support tool was done using Decisi-o-rama, an open-source Python library. With the developed decision support tool (uncertain) risk scores can be calculated for emerging chemical and microbial drinking water contaminants, which can be used for the evidence-based prioritisation of actions on emerging chemical and microbial drinking water risks. The decision support tool improves existing prioritisation approaches as it combines uncertain indicator levels with a multi-stakeholder approach and integrated the risk assessment of chemical and microbial contaminants. By applying the concept of value-focused thinking, this study addressed difficulties in evidence-ba, Sanitary Engineering, Policy Analysis

Learning multi-cultural team competencies is important for engineering students to prepare for an increasingly global workspace. We evaluated the game BAFÁ BAFÁ with groups of Master students from varying engineering programmes using a mixed methods approach. The game experience of 118 participants was measured. These participants experienced the game overall positively, although difficulties to understand other players in the game triggered mild stress and confusion. 91respondents also completed questionnaires before and after the game about certain attitudes, skills, and values related to working with people from other cultures: willingness (attitude) and ability (skill) to understand those people; and appreciation (value) of working with them. We used paired t-tests and qualitative analysis to determine the game’s effectiveness: after playing the game the players’ willingness increased significantly (t(90) = 3.6, p=.001), but their ability to do so decreased significantly (t(90) = 3.3, p=.001) and their appreciation remained constant (t(90) = 1.3, p=.195). The qualitative responses supported our quantitative results: after playing the BAFÁ BAFÁ game, players were more willing to understand people from other cultures. Moreover, players had become more aware of their own shortcomings in understanding people from other cultures. Finally, the learning effects were likely not caused by a test effect, since the appreciation (value) of working with people from other cultures had not increased after playing the game. We concluded that the BAFÁ BAFÁ game is a powerful instrument to embark upon teaching multi-cultural team skills, and therefore, to train more culturally aware engineers., Policy Analysis

Environmental decisions are complex as they are multi-dimensional, highly interdisciplinary and not only involve multiple stakeholders with conflicting objectives, but also many possible alternatives with uncertain consequences. The difficulty lies in making trade-offs between tough value trade-offs on the one hand while appreciating uncertain impacts of alternatives on the other. To support decisions tackling such problems, a combination of multi-criteria decision analysis (MCDA) and environmental models is promising yet limited by the available MCDA software. Here, we present Decisi-o-rama, an open-source Python MCDA library for single and sets (portfolios) of alternatives in the context of multi-attribute value/utility theory (MAUT/MAVT). Its development was driven by four aspirations that are crucial for usability in the context of environmental decision-making: (1) interoperability, (2) uncertainty-awareness, (3) computational efficiency, and (4) integration with portfolio decisions. The results indicate that these aspirations are met, thus facilitating the adoption of MCDA methods by environmental researchers and practitioners., Sanitary Engineering, Policy Analysis

Learning multi-cultural team competencies is important for engineering students to prepare for an increasingly global workspace. We evaluated the game BAFÁ BAFÁ with groups of Master students from varying engineering programmes using a mixed methods approach. The game experience of 118 participants was measured. These participants experienced the game overall positively, although difficulties to understand other players in the game triggered mild stress and confusion. 91respondents also completed questionnaires before and after the game about certain attitudes, skills, and values related to working with people from other cultures: willingness (attitude) and ability (skill) to understand those people; and appreciation (value) of working with them. We used paired t-tests and qualitative analysis to determine the game’s effectiveness: after playing the game the players’ willingness increased significantly (t(90) = 3.6, p=.001), but their ability to do so decreased significantly (t(90) = 3.3, p=.001) and their appreciation remained constant (t(90) = 1.3, p=.195). The qualitative responses supported our quantitative results: after playing the BAFÁ BAFÁ game, players were more willing to understand people from other cultures. Moreover, players had become more aware of their own shortcomings in understanding people from other cultures. Finally, the learning effects were likely not caused by a test effect, since the appreciation (value) of working with people from other cultures had not increased after playing the game. We concluded that the BAFÁ BAFÁ game is a powerful instrument to embark upon teaching multi-cultural team skills, and therefore, to train more culturally aware engineers., Policy Analysis

Environmental decisions are complex as they are multi-dimensional, highly interdisciplinary and not only involve multiple stakeholders with conflicting objectives, but also many possible alternatives with uncertain consequences. The difficulty lies in making trade-offs between tough value trade-offs on the one hand while appreciating uncertain impacts of alternatives on the other. To support decisions tackling such problems, a combination of multi-criteria decision analysis (MCDA) and environmental models is promising yet limited by the available MCDA software. Here, we present Decisi-o-rama, an open-source Python MCDA library for single and sets (portfolios) of alternatives in the context of multi-attribute value/utility theory (MAUT/MAVT). Its development was driven by four aspirations that are crucial for usability in the context of environmental decision-making: (1) interoperability, (2) uncertainty-awareness, (3) computational efficiency, and (4) integration with portfolio decisions. The results indicate that these aspirations are met, thus facilitating the adoption of MCDA methods by environmental researchers and practitioners., Sanitary Engineering, Policy Analysis

Recent developments in high- and middle-income countries have exhibited a shift from conventional urban water systems to alternative solutions that are more diverse in source separation, decentralization, and modularization. These solutions include nongrid, small-grid, and hybrid systems to address such pressing global challenges as climate change, eutrophication, and rapid urbanization. They close loops, recover valuable resources, and adapt quickly to changing boundary conditions such as population size. Moving to such alternative solutions requires both technical and social innovations to coevolve over time into integrated socio-technical urban water systems. Current implementations of alternative systems in high- and middle-income countries are promising, but they also underline the need for research questions to be addressed from technical, social, and transformative perspectives. Future research should pursue a transdisciplinary research approach to generating evidence through socio-technical "lighthouse" projects that apply alternative urban water systems at scale. Such research should leverage experiences from these projects in diverse socio-economic contexts, identify their potentials and limitations from an integrated perspective, and share their successes and failures across the urban water sector., Sanitary Engineering

Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced by historical decisions and implementations. The current decisions taken in sewer asset management will, therefore, have a long-lasting impact on the functionality and quality of future services provided by these networks. These decisions can be supported by different approaches ranging from various inspection techniques, deterioration models to assess the probability of failure or the technical service life, to sophisticated decision support systems crossing boundaries to other urban infrastructure. This paper presents the state of the art in sewer asset management in its manifold facets spanning a wide field of research and highlights existing research gaps while giving an outlook on future developments and research areas., Sanitary Engineering

Sewer pipes are commonly inspected in situ with CCTV equipment. The CCTV footage is then reviewed by human operators in order to classify defects in the pipes and make a recommendation on possible interventions. This process is both labor-intensive and error-prone. Other researchers have suggested machine learning techniques to (partially) automate the human review of this footage, but the automated classifiers are often validated in artificial testing setups, leading to biased results that do not translate directly to operational impact. In this work, we discuss suitable evaluation metrics for this specific classification task — most notably ‘specificity at sensitivity’ and ‘precision at recall’ — and the importance of using a validation setup that includes a realistic ratio of images with defects to images without defects, and a sufficiently large dataset. We also introduce ‘leave-two-inspections-out’ cross validation, designed to eliminate a data leakage bias that would otherwise cause an overestimation of classifier performance. We designed a convolutional neural network (CNN) and applied this validation methodology to automatically detect the twelve most common defect types in a dataset of over 2 million CCTV images. With this dataset and our validation methodology, our CNN outperforms the state-of-the-art. Classification performance was highest for intruding and defective connections and lowest for porous pipes. While the CNN is not capable of fully automated classification at sufficient performance levels, we determined that if we augment the human operator with the CNN, this may reduce the required human labor by up to 60.5%., Accepted Author Manuscript, Sanitary Engineering

Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced by historical decisions and implementations. The current decisions taken in sewer asset management will, therefore, have a long-lasting impact on the functionality and quality of future services provided by these networks. These decisions can be supported by different approaches ranging from various inspection techniques, deterioration models to assess the probability of failure or the technical service life, to sophisticated decision support systems crossing boundaries to other urban infrastructure. This paper presents the state of the art in sewer asset management in its manifold facets spanning a wide field of research and highlights existing research gaps while giving an outlook on future developments and research areas., Sanitary Engineering

Sewer pipes are commonly inspected in situ with CCTV equipment. The CCTV footage is then reviewed by human operators in order to classify defects in the pipes and make a recommendation on possible interventions. This process is both labor-intensive and error-prone. Other researchers have suggested machine learning techniques to (partially) automate the human review of this footage, but the automated classifiers are often validated in artificial testing setups, leading to biased results that do not translate directly to operational impact. In this work, we discuss suitable evaluation metrics for this specific classification task — most notably ‘specificity at sensitivity’ and ‘precision at recall’ — and the importance of using a validation setup that includes a realistic ratio of images with defects to images without defects, and a sufficiently large dataset. We also introduce ‘leave-two-inspections-out’ cross validation, designed to eliminate a data leakage bias that would otherwise cause an overestimation of classifier performance. We designed a convolutional neural network (CNN) and applied this validation methodology to automatically detect the twelve most common defect types in a dataset of over 2 million CCTV images. With this dataset and our validation methodology, our CNN outperforms the state-of-the-art. Classification performance was highest for intruding and defective connections and lowest for porous pipes. While the CNN is not capable of fully automated classification at sufficient performance levels, we determined that if we augment the human operator with the CNN, this may reduce the required human labor by up to 60.5%., Accepted Author Manuscript, Sanitary Engineering

Automatic leak localization has been suggested to reduce the time and personnel efforts needed to localize (small) leaks. Yet, the available methods require a detailed demand distribution model for successful calibration and good leak localization performance. The main aim of this work was to analyze whether such a detailed demand distribution is needed. Two demand distributions were used: a factorized distribution that distributes the inflow demand proportionally across the consumption nodes according to individual billing data, and a uniform distribution that equally distributes demand across all consumption nodes. The performance of the automatic leak localization method, using both demand distribution models, was compared. A new measure for leak localization performance that is based on the percentage of false positive nodes is proposed. It was possible to localize the leaks with both demand distribution models, although performance varied depending on the timing and duration of the measurement., Sanitary Engineering

Automatic leak localization has been suggested to reduce the time and personnel efforts needed to localize (small) leaks. Yet, the available methods require a detailed demand distribution model for successful calibration and good leak localization performance. The main aim of this work was to analyze whether such a detailed demand distribution is needed. Two demand distributions were used: a factorized distribution that distributes the inflow demand proportionally across the consumption nodes according to individual billing data, and a uniform distribution that equally distributes demand across all consumption nodes. The performance of the automatic leak localization method, using both demand distribution models, was compared. A new measure for leak localization performance that is based on the percentage of false positive nodes is proposed. It was possible to localize the leaks with both demand distribution models, although performance varied depending on the timing and duration of the measurement., Sanitary Engineering

We compare the use of multi-criteria decision analysis (MCDA)–or more precisely, models used in multi-attribute value theory (MAVT)–to integrated assessment (IA) models for supporting long-term water supply planning in a small town case study in Switzerland. They are used to evaluate thirteen system scale water supply alternatives in four future scenarios regarding forty-four objectives, covering technical, social, environmental, and economic aspects. The alternatives encompass both conventional and unconventional solutions and differ regarding technical, spatial and organizational characteristics. This paper focuses on the impact assessment and final evaluation step of the structured MCDA decision support process. We analyze the performance of the alternatives for ten stakeholders. We demonstrate the implications of model assumptions by comparing two IA and three MAVT evaluation model layouts of different complexity. For this comparison, we focus on the validity (ranking stability), desirability (value), and distinguishability (value range) of the alternatives given the five model layouts. These layouts exclude or include stakeholder preferences and uncertainties. Even though all five led us to identify the same best alternatives, they did not produce identical rankings. We found that the MAVT-type models provide higher distinguishability and a more robust basis for discussion than the IA-type models. The needed complexity of the model, however, should be determined based on the intended use of the model within the decision support process. The best-performing alternatives had consistently strong performance for all stakeholders and future scenarios, whereas the current water supply system was outperformed in all evaluation layouts. The best-performing alternatives comprise proactive pipe rehabilitation, adapted firefighting provisions, and decentralized water storage and/or treatment. We present recommendations for possible ways of improving water supply planning, Sanitary Engineering

The provision of sanitation service requires fulfilment of system processes including containment, conveyance, treatment, and disposal/reuse—or the sanitation value chain (Trémolet, 2011; Blackett et al., 2014; Tilley et al., 2014) as shown in Figure 1. The conveyance process is further divided into emptying and transport for decentralized system or faecal sludge management (FSM) system, and with sewerage network for centralized system or sewer-based (SB) system. For low and middle income countries, FSM is the norm covering 60-100% of the population (WSP, 2016). However, irrespective of the type of sanitation system, the problem lies on unsustainable sanitation projects due to unaccounted life cycle costs and incomplete consideration of the entire sanitation chain (Moriarty et al., 2011; Fonseca et al., 2011)., Sanitary Engineering

power point presentation, Sanitary Engineering

power point presentation, Sanitary Engineering

We compare the use of multi-criteria decision analysis (MCDA)–or more precisely, models used in multi-attribute value theory (MAVT)–to integrated assessment (IA) models for supporting long-term water supply planning in a small town case study in Switzerland. They are used to evaluate thirteen system scale water supply alternatives in four future scenarios regarding forty-four objectives, covering technical, social, environmental, and economic aspects. The alternatives encompass both conventional and unconventional solutions and differ regarding technical, spatial and organizational characteristics. This paper focuses on the impact assessment and final evaluation step of the structured MCDA decision support process. We analyze the performance of the alternatives for ten stakeholders. We demonstrate the implications of model assumptions by comparing two IA and three MAVT evaluation model layouts of different complexity. For this comparison, we focus on the validity (ranking stability), desirability (value), and distinguishability (value range) of the alternatives given the five model layouts. These layouts exclude or include stakeholder preferences and uncertainties. Even though all five led us to identify the same best alternatives, they did not produce identical rankings. We found that the MAVT-type models provide higher distinguishability and a more robust basis for discussion than the IA-type models. The needed complexity of the model, however, should be determined based on the intended use of the model within the decision support process. The best-performing alternatives had consistently strong performance for all stakeholders and future scenarios, whereas the current water supply system was outperformed in all evaluation layouts. The best-performing alternatives comprise proactive pipe rehabilitation, adapted firefighting provisions, and decentralized water storage and/or treatment. We present recommendations for possible ways of improving water supply planning, Sanitary Engineering

The provision of sanitation service requires fulfilment of system processes including containment, conveyance, treatment, and disposal/reuse—or the sanitation value chain (Trémolet, 2011; Blackett et al., 2014; Tilley et al., 2014) as shown in Figure 1. The conveyance process is further divided into emptying and transport for decentralized system or faecal sludge management (FSM) system, and with sewerage network for centralized system or sewer-based (SB) system. For low and middle income countries, FSM is the norm covering 60-100% of the population (WSP, 2016). However, irrespective of the type of sanitation system, the problem lies on unsustainable sanitation projects due to unaccounted life cycle costs and incomplete consideration of the entire sanitation chain (Moriarty et al., 2011; Fonseca et al., 2011)., Sanitary Engineering

Electrical Engineering, Mathematics and Computer Science, Software Technology, TI3806

Electrical Engineering, Mathematics and Computer Science, Software Technology, TI3806