scispace - formally typeset
Search or ask a question

Showing papers in "Journal of Water Resources Planning and Management in 2012"


Journal ArticleDOI
TL;DR: In this article, pressure reducing valves (PRVs) are used in water networks to prevent the downstream hydraulic grade from exceeding a set value, although they must be adequately located to maximize their effectiveness.
Abstract: During the past few years, issues concerning sustainable management of water distribution systems have attracted interest through an integrated policy aimed at reducing leakage through a pressure management strategy. Pressure reducing valves (PRVs) are often used in water networks to prevent the downstream hydraulic grade from exceeding a set value, although they must be adequately located to maximize their effectiveness. In recent years, the application of turbines or pumps operating as turbines (PATs) appeared as an alternative and sustainable solution to control network pressure and produce energy. In the present paper, PRVs and PATs were used within a district in a Naples’ water distribution network and showed large potential revenues and an attractive capital payback period.

150 citations


Journal ArticleDOI
TL;DR: Calibration is a process of comparing model results with field data and making the appropriate adjustments so that both results agree as mentioned in this paper, which can involve formal optimization methods or manual methods in which the modeler informally examines alternative model parameters.
Abstract: Calibration is a process of comparing model results with field data and making the appropriate adjustments so that both results agree. Calibration methods can involve formal optimization methods or manual methods in which the modeler informally examines alternative model parameters. The development of a calibration framework typically involves the following: (1) definition of the model variables, coefficients, and equations; (2) selection of an objective function to measure the quality of the calibration; (3) selection of the set of data to be used for the calibration process; and (4) selection of an optimization/manual scheme for altering the coefficient values in the direction of reducing the objective function. Hydraulic calibration usually involves the modification of system demands, fine-tuning the roughness values of pipes, altering pump operation characteristics, and adjusting other model attributes that affect simulation results, in particular those that have significant uncertainty assoc...

129 citations


Journal ArticleDOI
TL;DR: A deterministic network-based approach to study the relationship between the structure and function of water distribution systems and to critically review the application of structural measurements in the analysis of vulnerability and robustness of such systems is presented.
Abstract: A water distribution system, represented as a spatially organized graph, is a complex network of multiple interconnected nodes and links. The overall robustness of such a system, in addition to the reliability of individual components, depends on the underlying network structure. This paper presents a deterministic network-based approach to study the relationship between the structure and function of water distribution systems and to critically review the application of structural measurements in the analysis of vulnerability and robustness of such systems. Benchmark water supply networks are studied, and their level of resistance to random failures and targeted attacks on their bridges and cut-sets are explored. Qualitative concepts such as redundancy, optimal connectivity, and structural robustness are quantified. Among other measurements, two metrics of meshedness coefficient and algebraic connectivity are found of great use toward quantifying redundancy and optimal connectivity, respectively. A brief ...

114 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive view of demands in the enhanced WDN simulation models, including considerations of human-based, volume based, uncontrolled orifice based, and leakage-based demands as distinct types of network outflows.
Abstract: Solving water distribution network hydraulics depends to a great extent on demand representation in the related simulation models. The classical approach of simulation models for water distribution networks (WDNs) is described as demand-driven. The demands are fixed a priori in the model as an assumption or from field observations. Recently a more realist approach to predict the hydraulic system behavior, described as head/pressure-driven, better accounts for the fact that the demands depend in some ways on head status of the network. Thus, this paper presents a comprehensive view of demands in the enhanced WDN simulation models, including considerations of human- based, volume-based, uncontrolled orifice-based, and leakage-based demands as distinct types of network outflows. The paper proposes and discusses the representation of each type of demand in a comprehensive framework that is consistent with the hydraulic principles and the specific working condition. DOI: 10.1061/(ASCE)WR.1943-5452.0000187. © 2012 American Society of Civil Engineers. CE Database subject headings: Water distribution systems; Water demand; Algorithms; Simulation models. Author keywords: Water distribution networks; Water demands; Water network simulation; Global gradient algorithm; Pressure-driven analysis; Head-driven analysis.

111 citations


Journal ArticleDOI
TL;DR: In this article, the use of global sensitivity analysis as a screening tool to reduce the computational demands associated with multiobjective design and rehabilitation of water distribution systems (WDS) is investigated.
Abstract: This study investigates the use of global sensitivity analysis as a screening tool to reduce the computational demands associated with multiobjective design and rehabilitation of water distribution systems (WDS). Sobol’s method is used to screen insensitive decision variables and guide the formulation of reduced complexity WDS optimization problems (i.e., fewer decision variables). This sensitivity-informed problem decomposition dramatically reduces the computational demands associated with attaining high-quality approximations for optimal WDS trade-offs. This study demonstrates that the results for the reduced-complexity WDS problems can then be used to precondition and significantly enhance full search of the original WDS problem. Two case studies of increasing complexity—the New York Tunnels network and the Anytown network—are used to demonstrate the proposed methodology. In both cases, sensitivity analysis results reveal that WDS performance is strongly controlled by a small proportion of deci...

94 citations


Journal ArticleDOI
TL;DR: In this article, a multivariate statistical technique applied to the control of water inflows into district metering areas (DMAs) of urban networks is presented, called principal component analysis (PCA), which simplifies the original set of flow rate data recorded by the supervisory control and data acquisition (SCADA) system.
Abstract: The following work presents a multivariate statistical technique applied to the control of water inflows into district metering areas (DMAs) of urban networks. This technique, called principal-component analysis (PCA), allows for a sensitive and quick analysis of the inflows into a DMA without hassling mathematical algorithms. The PCA technique simplifies the original set of flow rate data recorded by the supervisory control and data acquisition (SCADA) system, synthesizing the most significant information into a statistical model that is able to explain most of the behavior of the water distribution network. The PCA technique also allows for the establishment of control charts that help system operators in the identification of anomalous behaviors regarding water use, bursts, or illegal connections. The described technique has been proven to offer high detection sensitivity to bursts or other unexpected consumptions.

92 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a technique for the detection of extended blockages in pressurized water pipelines by using the system frequency responses under transient conditions, and they demonstrated that the extended blockage in pipeline can be detected by the proposed method as long as the system resonant frequencies are accurately determined.
Abstract: This paper proposes a technique for the detection of extended blockages in pressurized water pipelines by using the system frequency responses under transient conditions. The impact of extended blockages on the system frequency responses is illustrated by using the analytical transfer matrix method, and the results indicate that extended blockages cause the resonant frequencies of the system to shift, and the blockage locations and sizes can be determined by analyzing the occurrences of the resonant peaks in the frequency axis. The analytical derivations of the blockage effect on the resonant frequencies are validated through different numerical experiments, and the applied results demonstrate that the extended blockages in pipeline can be detected by the proposed method as long as the system resonant frequencies are accurately determined. Practical implementations of the findings are discussed at the end of this paper.

84 citations


Journal ArticleDOI
TL;DR: In this paper, the assumption of diminishing marginal utility (i.e., concavity) of reservoir utility functions is used to model the water resources system, and the authors show that this is an important characteristic of water resources systems.
Abstract: Diminishing marginal utility is an important characteristic of water resources systems. With the assumption of diminishing marginal utility (i.e., concavity) of reservoir utility functions,...

84 citations


Journal ArticleDOI
TL;DR: In this paper, a multisite stochastic weather generator with a disaggregation technique for historical monthly flows of the Maipo river at El Manzano was combined with a daily water budget model.
Abstract: Agricultural regions located in snowmelt-dominated Mediterranean climate basins have been identified as being highly vulnerable to the impacts of climate change. The Maipo basin in central Chile is one such region. Projections of future climate conditions suggest major challenges for this basin. Precipitation levels are projected to decrease by the end of the century, and temperature levels in the mountains are expected to increase by around 3–4°C. Such changes would affect both river discharge and irrigation water demand. This paper illustrates potential climate change impacts on the hydroclimatological regime of the Maipo basin, focusing on irrigated agriculture and its demands on water use rights. The impact assessment was carried out by combining a multisite stochastic weather generator with a disaggregation technique for historical monthly flows of the Maipo river at El Manzano. Demand for irrigation was simulated with a daily water budget model. Data showed that water demands from irrigated ...

82 citations


Journal ArticleDOI
TL;DR: The Limari River basin is one of the most important watersheds in north-central Chile (30°S) and its headwaters lie at the top of the subtropical Andes (>5,000m above sea level) and the river flows westward into the Pacific Ocean over a length of approximately 200 km as mentioned in this paper.
Abstract: The Limari River basin is one of the most important watersheds in north-central Chile (30°S). Its headwaters lie at the top of the subtropical Andes (>5,000 m above sea level) and the river flows westward into the Pacific Ocean over a length of approximately 200 km. This basin has a marked snowmelt-driven hydrological regime and, in spite of the arid conditions that characterize this region, holds more than 50,000 ha of highly productive agricultural land thanks to its irrigation infrastructure and three interconnected reservoirs. Like many semiarid regions around the world, north-central Chile is expected to become warmer and drier during the 21st century as a consequence of ongoing anthropogenic climate change. The associated reduction in streamflow, changes in hydrograph timing, and enhanced evapotranspiration will undoubtedly threaten agriculture in the Limari basin and elsewhere in semiarid Chile. In this paper, the effect of temperature and precipitation on surface hydrology, performance of...

78 citations


Journal ArticleDOI
TL;DR: This study aimed two main objectives: first, the effect of local distribution lines in final system design is investigated, and second, a heuristic to improve the efficiency of meta-heuristic search methods is proposed.
Abstract: For the past three decades, a number of studies have been dedicated to water-distribution system (WDS) optimal design using alternative optimization algorithms. Many of those, however, focused on the introduction and application of new optimization techniques. Application systems optimized in previous studies are generally limited to simple transmission networks, so-called benchmark systems, in which local distribution lines were mostly excluded. Efforts seeking logical approaches to solve complex problems with large number of decisions are lacking. In this paper, logical and efficient approaches that could be utilized to optimize real-life scale WDS by the aid of existing optimization techniques are presented. This study aimed two main objectives: first, the effect of local distribution lines in final system design is investigated, and second, a heuristic to improve the efficiency of meta-heuristic search methods is proposed. Applications to real WDS demonstrate that (1) by integrating the transm...

Journal ArticleDOI
TL;DR: In this paper, the authors trace changes in the Delta conflict in game-theoretic terms, with its implications for the region's physical and ecological decline and governance, and provide insights on the potential for win-win solutions.
Abstract: California's Sacramento-San Joaquin Delta is the major hub of California's water supply system and is central to the ecosystem of many native threatened and endangered species. Conflicts over the Delta have evolved over more than a century. This paper traces changes in this conflict in game-theoretic terms, with its implications for the region's physical and ecological decline and governance. The Delta is not a zero-sum problem and win-win resolutions may exist if stakeholders cooperate. Game theory provides some insights on the potential for win- win solutions. The Delta problem has had a Prisoner's Dilemma structure, in which stakeholder self-interest makes cooperation unlikely within a reasonable time frame. However, the core of the Delta conflict is changing as the unsustainable future becomes more widely under- stood. Today's Delta problem has characteristics of a Chicken game, where cooperation is in everyone's interest, but it is unlikely because parties deviating from the status quo are likely to bear more of the costs of a long-term solution. The State of California may become the victim (or chicken) of the Delta game, bearing the greatest costs, if it continues to rely on leaving parties to develop voluntary cooperative solutions without a sufficient mechanism for enforcing cooperation. DOI: 10.1061/(ASCE)WR.1943-5452.0000164. © 2012 American Society of Civil Engineers. CE Database subject headings: California; Deltas; Water supply; Ecosystems. Author keywords: Game theory; Conflict resolution; Delta; CALFED; California; Chicken; Prisoner's dilemma.

Journal ArticleDOI
TL;DR: In this article, the authors explored the socioeconomic and environmental consequences of the regulation and test plans to improve water allocation management in the Yellow River Basin (YRB) in China by combining a decentralized optimization with a multiple-agent system (MAS) framework.
Abstract: The management of large river basins, such as the Yellow River Basin (YRB) in China, is complicated by distributed, localized decision processes and by mechanisms that coordinate local decisions and manage basin-level issues. Since 1998, the Yellow River Conservancy Commission (YRCC) has launched the Unified Water Flow Regulation (UWFR) as a centralized controlling mechanism that enforces an upper limit on water withdrawals (water use permits) for eight provinces located in the basin. The implementation of UWFR has maintained a prescribed minimum flow in the downstream channel and avoided the flow cutoff events that occurred every year between 1972 and 1998. This study attempts to explore the socioeconomic and environmental consequences of the regulation and test plans to improve water allocation management in the YRB. A decentralized optimization is combined with a multipleagent system (MAS) framework for the YRB, in which water users, reservoirs, and downstream ecological zones are defined as agents. This method iteratively determines water prices for each water use agent in the context of water market. The proposed water market scenario shows possible improvements of UWFR with respect to social, economic, and environmental objectives. DOI: 10.1061/(ASCE)WR.1943-5452.0000199. © 2012 American Society of Civil Engineers. CE Database subject headings: River basins; Optimization; Water supply; Pricing; China; Water allocation policy. Author keywords: River basin management; Multiple agent system (MAS); Disaggregated optimization; Water price; Water market; Yellow River Basin.

Journal ArticleDOI
TL;DR: In this paper, a novel approach for optimizing short-term scheduling of large-scale cascaded hydropower systems with multivibration zones of high head was presented, where standard deviation minimization relevant to the remaining load series for thermal systems was chosen as the objective nonlinear function.
Abstract: Construction of huge hydropower plants in the southern region of China has been rapidly increasing in recent years. These plants usually have multiple vibration zones of high head that have a great effect on short-term scheduling and real-time operations. This paper presents a novel approach for optimizing short-term scheduling of large-scale cascaded hydropower systems with multivibration zones of high head. For the purpose of cutting down peak loads, standard deviation minimization relevant to the remaining load series for thermal systems was chosen as the objective nonlinear function. Before the optimization, unit forbidden operation zones were identified by assembled mathematical techniques and hydro unit commitments were optimized using dynamic programming. The combined sets of forbidden operation zones and hydro unit commitments were repeatedly used during the search process. An optimization framework that combined the progressive optimality algorithm with a vibration zone avoidance strategy...

Journal ArticleDOI
TL;DR: In this paper, a pump power estimation method, developed using a false position method based optimization approach, is proposed to incorporate variable speed pumps in the conceptual design or planning of water transmission systems (WTSs), using optimi...
Abstract: Global warming caused by human activities presents serious global risks. Individuals, governments, and industries need to be more energy efficient and contribute to the mitigation of global warming by reducing their greenhouse gas (GHG) emissions. In previous research, GHG emission reduction has been identified as one important criterion in improving the sustainability of urban infrastructure and urban water systems. Within the water industry, opportunities exist for reducing GHG emissions by improving pumping efficiency via the use of variable-speed pumps (VSPs). Previously, VSPs have been used in the optimization of the operation of existing water distribution systems (WDSs). However, in WDS design optimization problems, fixed-speed pumps (FSPs) are commonly used. In this study, a pump power estimation method, developed using a false position method based optimization approach, is proposed to incorporate VSPs in the conceptual design or planning of water transmission systems (WTSs), using optimi...

Journal ArticleDOI
TL;DR: In this paper, the potential impact of water availability on future expansion of the thermoelectric power industry is estimated for a variety of alternative energy futures that differ according to the assumed mix of fuels utilized in new plant construction.
Abstract: In 2005, thermoelectric power accounted for 41% of all freshwater withdrawals and roughly 3% of all consumptive use in the United States. With the demand for electricity projected to increase by 24% by 2035 concerns have been raised as to the availability of water for this growing industry; particularly, as the siting of several new thermoelectric facilities have been challenged on the basis of water supply. To address this concern we estimate the potential impact of water availability on future expansion of the thermoelectric power industry. Specifically, both the extent and location of thermoelectric developments at risk due to limited fresh water supply is estimated for a variety of alternative energy futures that differ according to the assumed mix of fuels utilized in new plant construction. According to the analyzed scenarios water consumption for thermoelectric power generation is projected to increase by 36–43% between 1995 and 2035, with much of this development expected to occur in basin...

Journal ArticleDOI
TL;DR: A generic topological-based scheme to aid in the analysis of water-distribution systems is developed and demonstrated, which relies on clustering, which divides the distribution system into strongly and weakly connected sub-graphs using the depth first search (DFS) and breadthFirst search (BFS) graph algorithms.
Abstract: For large water-distribution systems fully detailed models result in a substantial amount of data, making it difficult to manage, monitor, and understand how the main structure of the system works. A possible way to cope with this difficulty is to gain insight to the system behavior by simplifying its operation through topological/connectivity analysis. The objective of this study is to develop and demonstrate a generic topological-based scheme to aid in the analysis of water-distribution systems. The methodology relies on clustering, which divides the distribution system into strongly and weakly connected sub-graphs using the depth first search (DFS) and breadth first search (BFS) graph algorithms. The partitioning results in a connectivity matrix that represents the interconnections between clusters, which can support, for example, a response modeling plan in case of a contamination intrusion incident. A detailed illustrative example and a real complex water-distribution system are explored for ...


Journal ArticleDOI
TL;DR: In this article, a general method to calibrate the proportional controllers for the real-time control (RTC) of motorized pressure valves in WDNs to reduce leakage during ordinary operation is presented.
Abstract: Pressure control is a key issue for the reduction of water loss through leakage in municipal water distribution networks (WDNs). The paper presents a general method to calibrate the proportional controllers for the real time control (RTC) of motorized pressure valves in WDNs to reduce leakage during ordinary operation. The method is based on the comprehensive dimensionless analysis of the behavior of simplified hydraulic systems under RTC scenarios. A numerical approach was used to derive a simple regressive relationship to tune the controller on the basis of the system dimensionless variables involved in the control process. The method was validated by application to a well-known bench-test water distribution network and compared with an existing literature calibration procedure. Results show that the proposed method allows for effective controller tuning and leads to performing leakage reduction-oriented real time control of pressures.

Journal ArticleDOI
TL;DR: In this paper, the authors present a mathematical model to optimize the management and operation of the Brazilian hydrothermal system, which consists of a large set of individual hydropower plants.
Abstract: This paper presents the development of a mathematical model to optimize the management and operation of the Brazilian hydrothermal system. The system consists of a large set of individual hydropowe...

Journal ArticleDOI
TL;DR: In this paper, the authors examined streamflow and water temperature regimes that could lead to long-term reductions in spring-run Chinook salmon (SRCS) in a California stream and evaluated management adaptations to ameliorate these impacts.
Abstract: Spring-run Chinook salmon (Oncorhynchus tshawytscha) are particularly vulnerable to climate change because adults over-summer in freshwater streams before spawning in autumn. We examined streamflow and water temperature regimes that could lead to long-term reductions in spring-run Chinook salmon (SRCS) in a California stream and evaluated management adaptations to ameliorate these impacts. Bias-corrected and spatially downscaled climate data from six general circulation models and two emission scenarios for the period 2010–2099 were used as input to two linked models: a water evaluation and planning (WEAP) model to simulate weekly mean streamflow and water temperature in Butte Creek, California that were used as input to SALMOD, a spatially explicit and size/stage structured model of salmon population dynamics in freshwater systems. For all climate scenarios and model combinations, WEAP yielded lower summer base flows and higher water temperatures relative to historical conditions, while SALMOD yi...

Journal ArticleDOI
TL;DR: The U.S. EPA's Global Change Research Program (GCRP) recently began an effort to address gaps in the current knowledge of the sensitivity of watershed data to potential future climate change, and the methodological challenges associated with integrating existing tools (e.g., climate models, land-use models, watershed models) and data sets as mentioned in this paper.
Abstract: The U.S. EPA’s Global Change Research Program (GCRP) recently began an effort to address gaps in the current knowledge of the sensitivity of U.S. streamflow, nutrient (nitrogen and phosphorus), and sediment loading to potential future climate change, and the methodological challenges associated with integrating existing tools (e.g., climate models, land-use models, watershed models) and data sets to address these scientific questions. The study is based on watershed modeling in 20 large U.S. watersheds. The purpose of this paper is to describe the overall structure of this ongoing effort—methods, sites, models, and scenarios—and discuss preliminary results generated to date for a subset of the watersheds. Specifically, a representative set of modeling results are reviewed that encompass the full suite of sensitivity tests explored in this project. These results illustrate a number of key methodological issues, sensitivities, and uncertainties associated with carrying out these types of climate cha...

Journal ArticleDOI
TL;DR: In this paper, the authors focus on the effect of human intervention on the landscape that may cause changes in the precipitation-runoff relationships at various temporal and spatial scales, and the occurrence of natural events such as volcanic explosions or forest fires, which may change the composition of the air, the soil surface, and geomorphology.
Abstract: Over the past three decades, hydrologists and water resources specialists have been concerned with the issue of nonstationarity arising from several factors. First is the effect of human intervention on the landscape that may cause changes in the precipitation–runoff relationships at various temporal and spatial scales. Second is the occurrence of natural events such as volcanic explosions or forest fires that may cause changes in the composition of the air, the soil surface, and geomorphology. Third is the low-frequency component of oceanic–atmospheric phenomena that may have significant effects on the variability of hydrological processes such as annual runoff, peak flows, and droughts. Fourth is global warming, which may cause changes to oceanic and atmospheric processes, thereby affecting the hydrological cycle at various temporal and spatial scales. There has been a significant amount of literature on the subject and thousands of research and project articles and books published in recent decades. Examples of human intrusion on the landscape are the changes in land use resulting from agricultural developments in semiarid and arid lands (e.g., Pielke et al. 2007, 2011), changes caused by large-scale deforestation (e.g., Gash and Nobre 1997), changes resulting from open-pit mining operations (e.g., Salas et al. 2008), and changes from increasing urbanization in watersheds (e.g., Konrad and Booth 2002, Villarini et al. 2009). These intrusions change hydrologic response characteristics such as the magnitude and timing of floods. In many situations, current systems and management practices will be ill equipped to cope with such changes unless adjustments are made. Large-scale landscape changes such as deforestation in the tropical regions can potentially alter atmospheric circulation patterns, and consequently affect global weather and climate (e.g., Lee et al. 2008, 2009). Major natural events, such as the volcanic explosion of Mount St. Helens in 1980 or the El Chichon volcanic explosion of 1982 induce a shock to the climate system in the form of global cooling that continues for several years. These events can also affect global circulation. Low-frequency climate drivers of the oceanic– atmospheric system such as the El Nino/Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), and Arctic Oscillation (AO) modulate global climate at interannual and multidecadal time scales. These drivers are the main sources of nonstationarity in global climate and hydrology. Large numbers of papers documenting the effect of these drivers on global hydroclimatology continue to emerge (e.g., Dilley and Heyman 1995; Mantua et al. 1997; Enfield et al. 2001; Akintug and Rasmussen 2005; Hamlet et al. 2005). In addition to climate variability and change due to the previously mentioned factors, anthropogenic warming of the oceans and atmosphere because of increased greenhouse gas concentrations and the ensuing changes to the hydrologic cycle are topics of serious pursuit. The international scientific community is making strides in understanding the potential warming and its effects on all aspects of climate variability [Intergovernmental Panel on Climate Change (IPCC) 2007], but the impacts on the hydrologic cycle remain debatable and inconclusive (e.g., Cohn and Lins 2005; Legates et al. 2005; Hirsch and Ryberg 2011). Based on analyses of the global mean CO2 (GMCO2) and annual flood records in the United States, no strong statistical evidence for flood magnitudes increasing with GMCO2 increases were found (Hirsch and Ryberg 2011). Although general circulation models have had success in the attribution of warming global temperatures to anthropogenic causes, their credibility and utility in reproducing variables that are relevant to hydrology and water resources applications is less clear. For example, the IPCC Report for Latin America acknowledges that “the current GCMs do not produce projections of changes in the hydrological cycle at regional scales with confidence. In particular the uncertainty of projections of precipitation remain high : : :That is a great limiting factor to the practical use of such projections for guiding active adaptation or mitigation policies” (Magrin et al. 2007; Boulanger et al. 2007). A variety of methods exist that address the concern of nonstationarity in hydrological processes and the topic remains an active research area. For example, in watersheds in which increasing urbanization has been documented causing significant effects in the flood response and magnitude, watershed modeling has been utilized to estimate the possible changes in the flood frequency and magnitude. Frequency analysis methods also have been applied when the parameters (or the moments such as the mean and variance) of a given model (e.g., the Gumbel model) may vary with time (e.g., Strupczewski et al. 2001; Clarke 2002). In addition, the role that low-frequency components of the oceanic– atmospheric system (represented, for example, by large-scale oscillations such as ENSO, PDO, and AMO) have on extreme events such as floods has been recognized. These large-scale forcing factors have been shown to exert in-phase and out-of-phase oscillations in the magnitude of floods, mean flows, and droughts

Journal ArticleDOI
TL;DR: In this article, a multistage stochastic linear programming (LP) model is developed to assist in the process of water system planning and management under demographic and climate change in Amman, Jordan, over the next 75 years.
Abstract: This research develops a multistage stochastic linear programming (LP) model to assist in the process of water system planning and management under demographic and climate change in Amman, Jordan, over the next 75 years. Climate change is projected to have a gradual exacerbating effect on Amman’s water stress over the next century, and water resources management strategies and policies put in place now will likely influence water use patterns for generations to come. A multistage decision model allows the identification of both adaptation strategies that should be implemented now and actions likely to be needed later, depending on future climate and demographic conditions. For Amman, the model recommends that household water reuse be expanded immediately, large-scale wastewater reclamation begin within 25 years, and mega-scale water import projects be postponed for several decades. Although these recommendations for the future will almost certainly change as additional information is acquired, by ...

Journal ArticleDOI
TL;DR: In this paper, a study was conducted to identify the best fit model using hourly consumption data from the water supply system of Araraquara, Sao Paulo, Brazil, which used Artificial Neural Networks (ANNs) to match or even improve on the regression model forecasts.
Abstract: This paper addresses the problem of water demand forecasting for real-time operation of Water Supply Systems. The present study was conducted to identify the best fit model using hourly consumption data from the Water Supply System of Araraquara, Sao Paulo, Brazil. Like most recent research, it uses Artificial Neural Networks (ANNs) in view of their enhanced capability to match or even improve on the regression model forecasts. The ANNs used were the Multilayer Perceptron with the Backpropagation algorithm (MLP-BP), the Dynamic Neural Network (DAN2) and two hybrid ANNs. The hybrid models use the error produced by the Fourier series forecasting as input to the MLP-BP and DAN2, called respectively ANN-H and DAN2-H. Other inputs, such as the demand and weather variables (temperature and humidity) were selected based on autocorrelation and correlation analysis, respectively. The results are promising with the hybrid models in general performing better than the usual ANN models. DAN2-H, identified as the best model, produced a Mean Absolute Error of 2.25 L/s and 2.06 L/s for training and test set respectively, which represent about 8% of the average consumption.

Journal ArticleDOI
TL;DR: In this article, the potential for deregulated markets to impact both a hydropower utility's revenue stream and downstream flow regimes was investigated, and the scale of any differences in flow regime resulting from full market participation is relative to a day-ahead only scenario.
Abstract: The flow regime of rivers is a complex but important measure of environmental quality and one that can be significantly impacted by conventional hydropower generation. While traditional hydropower scheduling creates a periodicity in downstream flows corresponding to seasonal and daily electricity demand patterns, deregulated electricity markets may provide financial incentives to further alter flows, as utilities respond to hourly market dynamics. This study investigates the potential for deregulated markets to impact both a hydropower utility’s revenue stream and downstream flow regimes. Six operating scenarios are explored: (1–2) full-market participation (including real-time energy), with and without flow reregulation; (3) day-ahead market only; and (4–6) run-of-river operations (ROR), with and without flood control and flow reregulation. Results suggest that, relative to a day-ahead-only scenario, the scale of any differences in flow regime resulting from full-market participation is relativel...

Journal ArticleDOI
TL;DR: In this article, an integrated water resources management model is developed to connect three groups of decision makers in pollution control, agricultural planning, and water resources allocation with economic, environmental, and social objectives.
Abstract: Sustainable development in river basins depends on sound management of land use and water allocation policies. Integrated water resources management (IWRM) is considered a path to bring many elements within the development schemes together toward a unified land-water planning and management process. In this study, an integrated water resources management model is developed to connect three groups of decision makers in pollution control, agricultural planning, and water resources allocation with economic, environmental, and social objectives. A genetic algorithm–based optimization model is developed for providing desirable water quality and quantity while maximizing agricultural production in the upstream region, mitigating the unemployment (social) impacts of land use changes, and providing reliable water supply to the downstream region. The upstream region is divided into subbasins, and a fuzzy-based multiobjective optimization model is used to determine the optimal land uses in each subbasin and...

Journal ArticleDOI
TL;DR: In this article, a sensitivity analysis is conducted to investigate the effect of electricity tariff and generation (emission factors) on the results of multiobjective WDS optimization accounting for both total economic cost (both capital and operating costs) and GHGs.
Abstract: Increased awareness of climate change has shifted the focus of water distribution system (WDS) optimization research from cost minimization only to the incorporation of energy or associated greenhouse gas (GHG) minimization. In this study, a sensitivity analysis is conducted to investigate the effect of electricity tariff and generation (emission factors) on the results of multiobjective WDS optimization accounting for both total economic cost (both capital and operating costs) and GHGs. A multiobjective genetic algorithm-based optimization approach is used to conduct the analysis. The results show that electricity tariff has a significant effect on the total economic cost of WDSs and the selection of optimal solutions. In contrast, the changes of emission factors in the future have a significant effect on the total GHGs from WDSs. However, it does not alter the final solutions on the Pareto-optimal front. DOI: 10.1061/(ASCE)WR.1943-5452.0000169. © 2012 American Society of Civil Engineers. CE Database subject headings: Water distribution systems; Optimization; Emissions; Climate change; Sensitivity analysis; Algorithms. Author keywords: Water distribution systems; Multiobjective optimization; Greenhouse gas emissions; Climate change; Sensitivity analysis; Genetic algorithms.

Journal ArticleDOI
TL;DR: In this article, the spatial fuzzy analytic hierarchical process (SFAHP) is proposed to support raster-based land-use suitability studies for the implementation of natural systems for wastewater treatment (NSWT) (constructed wetlands) in Greece.
Abstract: When decentralized strategies are considered for managing wastewater, natural systems for wastewater treatment (NSWT) (constructed wetlands) seem to be strongly preferred in comparison with the conventional activated sludge wastewater treatment systems. However, because of their high land requirements, land-use suitability analysis should be conducted to specify adequate areas for their accommodation. Multicriteria spatial decision support systems have emerged as the technology that takes into account both decision criteria and constraints in complex land-use planning problems. This study presents a multiattribute decision analysis approach called the spatial fuzzy Analytic Hierarchy Process (SFAHP) to support raster-based land-use suitability studies for the implementation of NSWT. The SFAHP enables decision makers to circumvent vagueness when they perform evaluations using linguistic variables. Its application in a region of Northeastern Greece using a two-level criteria hierarchical model demonstrates ...

Journal ArticleDOI
TL;DR: In this paper, the authors developed a short-term model for the optimal operation of hydropower reservoirs, which incorporates Muskingum channel routing, flow ramping constraints attributable to navigation requirements, and constraints on turbine operating regions, up/down time, and startup number.
Abstract: This paper develops a short-term model for the optimal operation of hydropower reservoirs. The model incorporates Muskingum channel routing, flow ramping constraints attributable to navigation requirements, and constraints on turbine operating regions, up/down time, and startup number. Lagrange multipliers are introduced to decompose the primal problem into a hydro subproblem and many individual unit subproblems, which are solved by the improved simplexlike method (SLM) and dynamic programming (DP). The Lagrange multipliers in the dual problem are updated by using an improved subgradient method, and the dual solution is modified to be feasible to the primal problem by using an efficient iterative policy. The method proposed has advantages in dealing with multiple identical units by defining united-generators to give a lower dimension and less execution time of the hydro subproblem. In a case study, the derived solution is very close to the optimal one, with a distance in benefit less than 0.55%.