<p>Subdaily extreme precipitation may trigger fast hydro-geomorphic respons... more <p>Subdaily extreme precipitation may trigger fast hydro-geomorphic responses, such as flash floods and debris flows, which cause numerous fatalities and large damage. Compared to coarser resolution models, high-resolution models, called convection-permitting (CPMs), more realistically represent convective processes that are key for the correct representation of subdaily extremes, and thus provide higher confidence in the future extreme estimates. However, due to the high computational demands, the existing CPM simulations are only available for relatively short time periods (10–20 years at most), too short for deriving precipitation frequency analyses with conventional approaches. Recent extreme value analysis methods, based on all “ordinary” observations rather than on just yearly maxima or a few values over a high threshold, offer an opportunity for exploiting these short data records to reliably estimate return levels associated with long return periods. Here, we examine subdaily precipitation extremes from three 10-year time slices (historical 1996-2005, near-future 2041-2050, and far future 2090-2099 – under the RCP8.5 scenario) of COSMO-crCLIM model simulations at 2.2 km resolution. We focus on the Eastern Alpine transect characterised by a complex orography, where significant changes in subdaily annual maxima have been already observed. We find that, although the storms' frequency will decrease in the region, the mean annual maxima will increase continuously in the near and far future, especially at shorter durations. Investigation of extreme return levels shows a similar trend, with larger changes in the far future. A shift in the seasonality is also reported, with extremes moving from late summer-autumn (historical), to autumn (near future), and autumn-winter (far future).</p>
Stochastic Environmental Research and Risk Assessment, 2020
This study investigates the effectiveness of the reduction policies of the apparent and real loss... more This study investigates the effectiveness of the reduction policies of the apparent and real losses of non-revenue water. For this purpose, using technique for order of preference by similarity to ideal solution (TOPSIS) model, a decision matrix is proposed, involving apparent and real losses risk reduction values induced by the implementation of each non-revenue water reduction policy. First, decision criteria, including technical, economic, and social criteria, were selected and introduced. Then, the technical criterion was calculated using a fuzzy Bayesian model. In the following, using group decision-making and analytic hierarchy process method, the criteria were weighted. In the next step, the bests of decision criteria were determined by the TOPSIS method. This method was applied in the water distribution network of district 4 of Tehran, Iran. The results indicated that the most basic non-revenue water reduction policy by risk-based group decision-making is to identify unauthorized connections in the apparent water loss sector and increase the speed and quality of maintenance and repairs in the real water loss sector.
Proper functioning of a sewage collection network whole depends heavily on its management plan. P... more Proper functioning of a sewage collection network whole depends heavily on its management plan. Prioritizing component inspection of these networks is also an important part of management plan and paying attention to it can greatly improve their performance. In the present study, after determining the factors affecting the structural deterioration process of sewers, the impact of each of these factors on their decision-making and inspection prioritization process is investigated. After defining the indices and determining how each index is scored, each of the indices is classified in the range of 1 (very good) to 5 (very bad). Subsequently, a deterioration model based on polynomial logistic regression was developed to estimate the structural status of components using defined structural indices and videometric data. In addition, hydraulic and environmental assessment indices of sewers were introduced, which classified the condition of sewers in the range of 1 (very good) to 5 (very ...
Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted a... more Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted as an issue which mankind needs to address. The starting point is necessarily the determination of all the sources of emissions during the life-cycles of the studied components. Post-calculation, the results ought to be presented to decision-makers in a clear manner so as to provide the basis on which corrective actions could be considered. This paper calculates the GHGs emissions during the life-cycle of wastewater pipelines and introduces a different approach to communicate information about GHGs released, to decision-makers. Different diameters of concrete and high-density polyethylene (HDPE) wastewater pipes are compared in a case study. Results show that the total CO2-equivalent (CO2-eq) emissions attributed to concrete pipes are greater than HDPE pipes. Hence, the equivalent bio-productive area of forest required to sequester the CO2 (the major GHG) and its corresponding costs will ...
Stochastic Environmental Research and Risk Assessment, 2020
This study investigates the effectiveness of the reduction policies of the apparent and real loss... more This study investigates the effectiveness of the reduction policies of the apparent and real losses of non-revenue water. For this purpose, using technique for order of preference by similarity to ideal solution (TOPSIS) model, a decision matrix is proposed, involving apparent and real losses risk reduction values induced by the implementation of each non-revenue water reduction policy. First, decision criteria, including technical, economic, and social criteria, were selected and introduced. Then, the technical criterion was calculated using a fuzzy Bayesian model. In the following, using group decision-making and analytic hierarchy process method, the criteria were weighted. In the next step, the bests of decision criteria were determined by the TOPSIS method. This method was applied in the water distribution network of district 4 of Tehran, Iran. The results indicated that the most basic non-revenue water reduction policy by risk-based group decision-making is to identify unauthorized connections in the apparent water loss sector and increase the speed and quality of maintenance and repairs in the real water loss sector.
Proper functioning of a sewage collection network whole depends heavily on its management plan. P... more Proper functioning of a sewage collection network whole depends heavily on its management plan. Prioritizing component inspection of these networks is also an important part of management plan and paying attention to it can greatly improve their performance. In the present study, after determining the factors affecting the structural deterioration process of sewers, the impact of each of these factors on their decision-making and inspection prioritization process is investigated. After defining the indices and determining how each index is scored, each of the indices is classified in the range of 1 (very good) to 5 (very bad). Subsequently, a deterioration model based on polynomial logistic regression was developed to estimate the structural status of components using defined structural indices and videometric data. In addition, hydraulic and environmental assessment indices of sewers were introduced, which classified the condition of sewers in the range of 1 (very good) to 5 (very ...
Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted a... more Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted as an issue which mankind needs to address. The starting point is necessarily the determination of all the sources of emissions during the life-cycles of the studied components. Post-calculation, the results ought to be presented to decision-makers in a clear manner so as to provide the basis on which corrective actions could be considered. This paper calculates the GHGs emissions during the life-cycle of wastewater pipelines and introduces a different approach to communicate information about GHGs released, to decision-makers. Different diameters of concrete and high-density polyethylene (HDPE) wastewater pipes are compared in a case study. Results show that the total CO2-equivalent (CO2-eq) emissions attributed to concrete pipes are greater than HDPE pipes. Hence, the equivalent bio-productive area of forest required to sequester the CO2 (the major GHG) and its corresponding costs will ...
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use.
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use.
AbstractIn recent years, reverse osmosis (RO) systems have been highly utilized in industrial pro... more AbstractIn recent years, reverse osmosis (RO) systems have been highly utilized in industrial processes. One of the most important operational issues of these systems is membrane fouling, which lea...
This paper aims to initially, identify effective factors of Non Revenue Water (NRW) and its three... more This paper aims to initially, identify effective factors of Non Revenue Water (NRW) and its three major components: apparent losses, real losses and non-revenue authorized consumptions in water distribution networks. In the next step, they should be ranked according to their potential in the reduction of the amount of NRW. Besides, incidence of each NRW components imposes some special economic and social impacts. In the present study, by considering data scarcity and uncertainty of the available data and information, risk assessment of NRW and its components has been done through two stages. The first stage is initiated by designing a questionnaire so as to collect data and information about 41 identified parameters in part of Tehran Water and Wastewater Company as the research pilot. Then, in order to demonstrate the probability relationships between factors influencing NRW components, Bayesian Network (BN) is used. At the end of this stage, the parameters are prioritized in Water Resour Manage
Abstract Sewer condition prediction is a fundamental element of proactive maintenance programs. T... more Abstract Sewer condition prediction is a fundamental element of proactive maintenance programs. The prediction relies mostly on the assessed condition of inspected segments, generally based on CCTV reports. However, several sources of uncertainty affect the condition assessment and may lead to inefficient maintenance. The present article focuses on three main questions. 1. What is the impact of uncertainty in assessed condition on the prediction model? 2. Considering uncertainties in the assessed condition, is it necessary to collect data on the characteristics of many segments, or are a small number of influential variables enough to build the condition prediction model? 3. Is it better to overestimate (false positive) or underestimate (false negative) the deterioration of a segment? These questions were evaluated on a semi-virtual asset stock and the results confirm that uncertainties affect the inspection efficiency negatively. Results also show that errors leading to the overestimation of the deterioration have less negative impact. The study suggests that data from a small number of influential segments is adequate to inform the prediction model.
The main purpose of wastewater treatment is to protect humans against waterborne diseases and to ... more The main purpose of wastewater treatment is to protect humans against waterborne diseases and to safeguard aquatic bio-resources like fish. The dominating environmental concerns within this domain are indeed still potential aquatic eutrophication/oxygen depletion due to nutrient/organic matter emissions and potential health impacts due to spreading of pathogens. Anyway, the use of treatment for micro-pollutants is increasing and a paradigm shift is ongoingwastewater is more and more considered as a resource of, e.g. energy, nutrients and even polymers, in the innovations going on. The focus of LCA studies addressing wastewater treatment have from the very first published cases, been on energy and resource consumption. In recent time, the use of characterisation has increased and besides global warming potential, especially eutrophication is in focus. Even the toxicity-related impact categories are nowadays included more often. Application of LCA for comparing avoided against induced impacts, and hereby identifying trade-offs when introducing new technology, is increasingly used. A typical functional unit is the treatment of one cubic metre of wastewater which should be well defined regarding composition. Depending on the goal and scope of the study, all life cycle stages have the potential of being significant, though disposal of infrastructure seems to be the least important for the impact profile in many cases. No inventory data and none of the conventional impact categories (except stratospheric ozone depletion if emission of N 2 O is excluded) should be ruled out; but eutrophication and ecotoxicity are in many cases among the dominating ones.
Environmental impacts of civil projects are one of the most important aspects of these kinds of p... more Environmental impacts of civil projects are one of the most important aspects of these kinds of projects. To achieving sustainable development, managers of these projects should monitor the environmental impacts of their activities carefully. Implementation and operation phases of civil projects need to use of natural resources for material production and maintenance activities related to them. The issue of climate change, affected by using natural resources and industrial production, brings up the environmental impacts as an important factor in decision making process. Since global warming effect has so many direct and indirect impacts on the ecosystem, this paper is dedicated to this kind of environmental impacts of wastewater collection systems. To achieving this goal, considering the carbon footprint, which expresses as carbon dioxide equivalents, as an environmental sustainability indicator can be useful in carbon-regulated environment issues (e.g., carbon tax or carbon trading...
<p>Subdaily extreme precipitation may trigger fast hydro-geomorphic respons... more <p>Subdaily extreme precipitation may trigger fast hydro-geomorphic responses, such as flash floods and debris flows, which cause numerous fatalities and large damage. Compared to coarser resolution models, high-resolution models, called convection-permitting (CPMs), more realistically represent convective processes that are key for the correct representation of subdaily extremes, and thus provide higher confidence in the future extreme estimates. However, due to the high computational demands, the existing CPM simulations are only available for relatively short time periods (10–20 years at most), too short for deriving precipitation frequency analyses with conventional approaches. Recent extreme value analysis methods, based on all “ordinary” observations rather than on just yearly maxima or a few values over a high threshold, offer an opportunity for exploiting these short data records to reliably estimate return levels associated with long return periods. Here, we examine subdaily precipitation extremes from three 10-year time slices (historical 1996-2005, near-future 2041-2050, and far future 2090-2099 – under the RCP8.5 scenario) of COSMO-crCLIM model simulations at 2.2 km resolution. We focus on the Eastern Alpine transect characterised by a complex orography, where significant changes in subdaily annual maxima have been already observed. We find that, although the storms' frequency will decrease in the region, the mean annual maxima will increase continuously in the near and far future, especially at shorter durations. Investigation of extreme return levels shows a similar trend, with larger changes in the far future. A shift in the seasonality is also reported, with extremes moving from late summer-autumn (historical), to autumn (near future), and autumn-winter (far future).</p>
Stochastic Environmental Research and Risk Assessment, 2020
This study investigates the effectiveness of the reduction policies of the apparent and real loss... more This study investigates the effectiveness of the reduction policies of the apparent and real losses of non-revenue water. For this purpose, using technique for order of preference by similarity to ideal solution (TOPSIS) model, a decision matrix is proposed, involving apparent and real losses risk reduction values induced by the implementation of each non-revenue water reduction policy. First, decision criteria, including technical, economic, and social criteria, were selected and introduced. Then, the technical criterion was calculated using a fuzzy Bayesian model. In the following, using group decision-making and analytic hierarchy process method, the criteria were weighted. In the next step, the bests of decision criteria were determined by the TOPSIS method. This method was applied in the water distribution network of district 4 of Tehran, Iran. The results indicated that the most basic non-revenue water reduction policy by risk-based group decision-making is to identify unauthorized connections in the apparent water loss sector and increase the speed and quality of maintenance and repairs in the real water loss sector.
Proper functioning of a sewage collection network whole depends heavily on its management plan. P... more Proper functioning of a sewage collection network whole depends heavily on its management plan. Prioritizing component inspection of these networks is also an important part of management plan and paying attention to it can greatly improve their performance. In the present study, after determining the factors affecting the structural deterioration process of sewers, the impact of each of these factors on their decision-making and inspection prioritization process is investigated. After defining the indices and determining how each index is scored, each of the indices is classified in the range of 1 (very good) to 5 (very bad). Subsequently, a deterioration model based on polynomial logistic regression was developed to estimate the structural status of components using defined structural indices and videometric data. In addition, hydraulic and environmental assessment indices of sewers were introduced, which classified the condition of sewers in the range of 1 (very good) to 5 (very ...
Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted a... more Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted as an issue which mankind needs to address. The starting point is necessarily the determination of all the sources of emissions during the life-cycles of the studied components. Post-calculation, the results ought to be presented to decision-makers in a clear manner so as to provide the basis on which corrective actions could be considered. This paper calculates the GHGs emissions during the life-cycle of wastewater pipelines and introduces a different approach to communicate information about GHGs released, to decision-makers. Different diameters of concrete and high-density polyethylene (HDPE) wastewater pipes are compared in a case study. Results show that the total CO2-equivalent (CO2-eq) emissions attributed to concrete pipes are greater than HDPE pipes. Hence, the equivalent bio-productive area of forest required to sequester the CO2 (the major GHG) and its corresponding costs will ...
Stochastic Environmental Research and Risk Assessment, 2020
This study investigates the effectiveness of the reduction policies of the apparent and real loss... more This study investigates the effectiveness of the reduction policies of the apparent and real losses of non-revenue water. For this purpose, using technique for order of preference by similarity to ideal solution (TOPSIS) model, a decision matrix is proposed, involving apparent and real losses risk reduction values induced by the implementation of each non-revenue water reduction policy. First, decision criteria, including technical, economic, and social criteria, were selected and introduced. Then, the technical criterion was calculated using a fuzzy Bayesian model. In the following, using group decision-making and analytic hierarchy process method, the criteria were weighted. In the next step, the bests of decision criteria were determined by the TOPSIS method. This method was applied in the water distribution network of district 4 of Tehran, Iran. The results indicated that the most basic non-revenue water reduction policy by risk-based group decision-making is to identify unauthorized connections in the apparent water loss sector and increase the speed and quality of maintenance and repairs in the real water loss sector.
Proper functioning of a sewage collection network whole depends heavily on its management plan. P... more Proper functioning of a sewage collection network whole depends heavily on its management plan. Prioritizing component inspection of these networks is also an important part of management plan and paying attention to it can greatly improve their performance. In the present study, after determining the factors affecting the structural deterioration process of sewers, the impact of each of these factors on their decision-making and inspection prioritization process is investigated. After defining the indices and determining how each index is scored, each of the indices is classified in the range of 1 (very good) to 5 (very bad). Subsequently, a deterioration model based on polynomial logistic regression was developed to estimate the structural status of components using defined structural indices and videometric data. In addition, hydraulic and environmental assessment indices of sewers were introduced, which classified the condition of sewers in the range of 1 (very good) to 5 (very ...
Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted a... more Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted as an issue which mankind needs to address. The starting point is necessarily the determination of all the sources of emissions during the life-cycles of the studied components. Post-calculation, the results ought to be presented to decision-makers in a clear manner so as to provide the basis on which corrective actions could be considered. This paper calculates the GHGs emissions during the life-cycle of wastewater pipelines and introduces a different approach to communicate information about GHGs released, to decision-makers. Different diameters of concrete and high-density polyethylene (HDPE) wastewater pipes are compared in a case study. Results show that the total CO2-equivalent (CO2-eq) emissions attributed to concrete pipes are greater than HDPE pipes. Hence, the equivalent bio-productive area of forest required to sequester the CO2 (the major GHG) and its corresponding costs will ...
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use.
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use.
AbstractIn recent years, reverse osmosis (RO) systems have been highly utilized in industrial pro... more AbstractIn recent years, reverse osmosis (RO) systems have been highly utilized in industrial processes. One of the most important operational issues of these systems is membrane fouling, which lea...
This paper aims to initially, identify effective factors of Non Revenue Water (NRW) and its three... more This paper aims to initially, identify effective factors of Non Revenue Water (NRW) and its three major components: apparent losses, real losses and non-revenue authorized consumptions in water distribution networks. In the next step, they should be ranked according to their potential in the reduction of the amount of NRW. Besides, incidence of each NRW components imposes some special economic and social impacts. In the present study, by considering data scarcity and uncertainty of the available data and information, risk assessment of NRW and its components has been done through two stages. The first stage is initiated by designing a questionnaire so as to collect data and information about 41 identified parameters in part of Tehran Water and Wastewater Company as the research pilot. Then, in order to demonstrate the probability relationships between factors influencing NRW components, Bayesian Network (BN) is used. At the end of this stage, the parameters are prioritized in Water Resour Manage
Abstract Sewer condition prediction is a fundamental element of proactive maintenance programs. T... more Abstract Sewer condition prediction is a fundamental element of proactive maintenance programs. The prediction relies mostly on the assessed condition of inspected segments, generally based on CCTV reports. However, several sources of uncertainty affect the condition assessment and may lead to inefficient maintenance. The present article focuses on three main questions. 1. What is the impact of uncertainty in assessed condition on the prediction model? 2. Considering uncertainties in the assessed condition, is it necessary to collect data on the characteristics of many segments, or are a small number of influential variables enough to build the condition prediction model? 3. Is it better to overestimate (false positive) or underestimate (false negative) the deterioration of a segment? These questions were evaluated on a semi-virtual asset stock and the results confirm that uncertainties affect the inspection efficiency negatively. Results also show that errors leading to the overestimation of the deterioration have less negative impact. The study suggests that data from a small number of influential segments is adequate to inform the prediction model.
The main purpose of wastewater treatment is to protect humans against waterborne diseases and to ... more The main purpose of wastewater treatment is to protect humans against waterborne diseases and to safeguard aquatic bio-resources like fish. The dominating environmental concerns within this domain are indeed still potential aquatic eutrophication/oxygen depletion due to nutrient/organic matter emissions and potential health impacts due to spreading of pathogens. Anyway, the use of treatment for micro-pollutants is increasing and a paradigm shift is ongoingwastewater is more and more considered as a resource of, e.g. energy, nutrients and even polymers, in the innovations going on. The focus of LCA studies addressing wastewater treatment have from the very first published cases, been on energy and resource consumption. In recent time, the use of characterisation has increased and besides global warming potential, especially eutrophication is in focus. Even the toxicity-related impact categories are nowadays included more often. Application of LCA for comparing avoided against induced impacts, and hereby identifying trade-offs when introducing new technology, is increasingly used. A typical functional unit is the treatment of one cubic metre of wastewater which should be well defined regarding composition. Depending on the goal and scope of the study, all life cycle stages have the potential of being significant, though disposal of infrastructure seems to be the least important for the impact profile in many cases. No inventory data and none of the conventional impact categories (except stratospheric ozone depletion if emission of N 2 O is excluded) should be ruled out; but eutrophication and ecotoxicity are in many cases among the dominating ones.
Environmental impacts of civil projects are one of the most important aspects of these kinds of p... more Environmental impacts of civil projects are one of the most important aspects of these kinds of projects. To achieving sustainable development, managers of these projects should monitor the environmental impacts of their activities carefully. Implementation and operation phases of civil projects need to use of natural resources for material production and maintenance activities related to them. The issue of climate change, affected by using natural resources and industrial production, brings up the environmental impacts as an important factor in decision making process. Since global warming effect has so many direct and indirect impacts on the ecosystem, this paper is dedicated to this kind of environmental impacts of wastewater collection systems. To achieving this goal, considering the carbon footprint, which expresses as carbon dioxide equivalents, as an environmental sustainability indicator can be useful in carbon-regulated environment issues (e.g., carbon tax or carbon trading...
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