| publications-4711 |
article |
2002 |
Pahlβ€Wostl, Claudia and Pahl-Wostl, Claudia |
Towards sustainability in the water sector – The importance of human actors and processes of social learning |
Aquatic Sciences |
10.1007/pl00012594 |
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Current regimes in resource management are often unsustainable as judged by ecological, economic and social criteria. Many technological resource management regimes are inflexible and not built to adapt to changes in environmental, economic or social circumstances. This inflexibility poses problems in a world characterized by fast change. The water sector is currently undergoing major processes of transformation at local, regional and global scales. Today's situation is challenged by uncertainties, e.g., in water demand (diminishing in industrialized countries, rising in developing countries), by worsening water quality, by pressure for cost-efficient solutions, and by fast changing socio-economic boundary conditions. One expects additional uncertainties, due to climate change, such as a shift in the pattern of extreme events. Hence, new strategies and institutional arrangements are required to cope with risk and change in general. When one considers processes of transformation and change, the human dimension is of particular importance. Institutions and rule systems may cause resistance to change but can also enable and facilitate necessary transformation processes. This paper explores conceptual approaches in social learning and adaptive management. It introduces agent-based modelling, and the link between analytical modelling and participatory approaches as promising new developments to explore and foster changes towards sustainability and the required transformations in technological regimes and institutional settings. |
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| publications-4712 |
article |
2003 |
Kalungi, Paul and Kalungi, Paul and Tanyimboh, Tiku T. and Tanyimboh, Tiku T. |
Redundancy model for water distribution systems |
Reliability Engineering & System Safety |
10.1016/s0951-8320(03)00168-6 |
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| publications-4713 |
article |
2004 |
Taylor, R. Garth and Taylor, R. G. and McKean, John R. and McKean, John R. and Young, Robert H. and Young, Robert A. |
Alternate Price Specifications for Estimating Residential Water Demand with Fixed Fees |
Land Economics |
10.2307/3654732 |
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Using a new model formulation and data from a sample of Colorado utilities, we investigated the price specification controversy (marginal price versus average revenue) when estimating residential water demand. The improved statistical fit using average revenue as the price variable was shown to be an artifact of the unitary elastic identity created when monthly rate schedules contain a fixed fee. When the fixed fee was purged from the data, average price was not significant, but marginal price remained significant. In the preferred double-log marginal price model, estimated price elasticity was –0.3, and conservation programs had no significant effect on water use. |
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| publications-4714 |
article |
2005 |
Mahinthakumar, G. and Mahinthakumar, G. (Kumar) and Saad, Mohamed and Sayeed, Mohamed |
Hybrid Genetic Algorithmβ€”Local Search Methods for Solving Groundwater Source Identification Inverse Problems |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2005)131:1(45) |
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Identifying contaminant sources in groundwater is important for developing effective remediation strategies and identifying responsible parties in a contamination incident. Groundwater source identification problems require solution of an inverse problem. Gradient-based local optimization approaches are among the most popular approaches for solving these inverse problems. While these methods are sometimes appropriate, they are not effective for problems that contain several local minima and for problems where the decision space is highly discontinuous or convoluted. For these types of problems, heuristic global search approaches such as genetic algorithms (GAs) are more effective. But methods such as GAs are inefficient for fine-tuning solutions once a near global minimum is found. For problems that contain several local minima, a hybrid approach starting with a global method and then fine-tuning with a local method may be more attractive, especially if the decision space is reasonably well behaved near t... |
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| publications-4715 |
article |
2008 |
Firth, Steven and Firth, Steven K. and Lomas, Kevin J. and Lomas, Kevin J. and Wright, A. J. and Wright, Andrew J. and Wall, Rob and Wall, Rob |
Identifying trends in the use of domestic appliances from household electricity consumption measurements |
Energy and Buildings |
10.1016/j.enbuild.2007.07.005 |
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Abstract Results are presented from a monitoring study of the electricity consumption of a sample of UK domestic buildings. Five-minutely average whole house power consumption was recorded for 72 dwellings at five sites over a 2-year monitoring period. The mean annual electricity consumption for the households increased significantly by 4.5\% ( t =1.9; p |
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| publications-4716 |
article |
2008 |
Cutore, P. and Cutore, P. and Campisano, Alberto and Campisano, Alberto and Kapelan, Zoran and Kapelan, Zoran and Modica, Carlo and Modica, Carlo and Savić, Dragan and Savic, Dragan |
Probabilistic prediction of urban water consumption using the SCEM-UA algorithm |
Urban Water Journal |
10.1080/15730620701754434 |
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Prediction of urban water consumption can help to improve the performance of water distribution systems. Despite the obvious presence of uncertainty in measurements and in assumed model types/structures, most of the existing water consumption prediction models are developed and used in a deterministic context. Methods for more realistic assessment of parameter and model prediction uncertainties have begun to appear in literature only recently. A novel application of the Shuffled Complex Evolution Metropolis algorithm (SCEM-UA) for the calibration of a water consumption prediction model is proposed here. The model is applied to a case study of the city of Catania (Italy) with the aim to predict daily water consumption. The SCEM-UA algorithm is used to calibrate the parameters of the artificial neural network based prediction model and in turn to determine the associated parameter and model prediction uncertainties. The results obtained using the SCEM-UA ANN approach were compared to the corresponding resul... |
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| publications-4717 |
article |
2008 |
Balling, Robert C. and Balling, Robert C. and Gober, Patricia and Gober, Patricia and Jones, Nancy S. and Jones, N. |
Sensitivity of residential water consumption to variations in climate: An intraurban analysis of Phoenix, Arizona |
Water Resources Research |
10.1029/2007wr006722 |
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[1]Water remains an essential ingredient for the rapid population growth taking place in metropolitan Phoenix, Arizona. Depending upon the municipality, between 60 and 75\% of residential water is used outdoors to maintain nonnative, water-intensive landscapes and swimming pools. Residential water use in Phoenix should be especially sensitive to meteorological and climatic variations because of the strong emphasis on outdoor water use. This study explores the intraurban spatial variations in the sensitivity of residential water consumption to atmospheric conditions. For 230 census tracts in the city, we developed times series of monthly water use anomalies and compared them with monthly anomalies of temperature, precipitation, and the Palmer Drought Hydrological Index. We found that one third of census tracts have little to no sensitivity to climate, while one tract had over 70\% of its monthly variance in water use explained by atmospheric conditions. Greater sensitivity to atmospheric conditions occurred in census tracts with large lots, many pools, a high proportion of irrigated mesic landscaping, and a high proportion of high-income residents. Low climatic sensitivity occurred in neighborhoods with large families and many Hispanics. Results suggest that more affluent, non-Hispanic neighborhoods will be disproportionately affected by increasing temperatures due to urban heat island effects and the buildup of greenhouse gases. |
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| publications-4718 |
article |
2010 |
Giustolisi, Orazio and Giustolisi, Orazio |
Considering Actual Pipe Connections in Water Distribution Network Analysis |
Journal of Hydraulic Engineering |
10.1061/(asce)hy.1943-7900.0000266 |
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The classical assumption of representing total demand along a pipe as two lumped withdrawals at its terminal nodes is hitherto common. It is a simplification of the network topology which is useful in order to drastically reduce the number of nodes during network simulation. Conversely, this simplification does not preserve energy balance equation of pipes and, for this reason, it is an approximation that could generate significant head loss errors. This paper presents a modification of the global gradient algorithm (GGA) which entails an enhancing of GGA (EGGA) permitting the effective introduction of the lumped nodal demands, without forfeiting correctness of energy balance, by means of a pipe hydraulic resistance correction. The robustness and convergence properties of the algorithm are compared with those of the classical GGA. Furthermore, the effectiveness of EGGA is demonstrated by computing the network pressure status under different configurations of the connections along the pipes of a test network. |
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| publications-4719 |
article |
2010 |
Wu, Zheng Yi and Wu, Zheng Yi and Sage, Paul and Sage, Paul and Turtle, David and Turtle, David |
Pressure-dependent leak detection model and its application to a district water system |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2010)136:1(116) |
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Cost-effective reduction of water loss is a compelling but challenging task for water utilities. This paper presents a model-based optimization method for leakage detection of water distribution systems. Leakage hotspots are assumed to exist at the model nodes identified. Leakage is represented as pressure-dependent demand simulated as emitter flows at selected model nodes. The leakage detection method is formulated to optimize the leakage node locations and their associated emitter coefficients such that the differences between the model predicted and the field observed values for pressure and flow are minimized. The optimization problem is solved by using a competent genetic algorithm. The leakage detection method is developed as an add-on feature of the optimization-based model calibration tool. This enables engineers to undertake leakage hotspot optimization as an independent task or combine the task with hydraulic model calibration, subject to suitably varied field data. Two case studies are discusse... |
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| publications-4720 |
article |
2013 |
Bennett, Christopher J. and Bennett, Christopher Joseph and Stewart, Rodney Anthony and Stewart, Rodney Anthony and Beal, Cara and Beal, Cara |
ANN-based residential water end-use demand forecasting model |
Expert Systems With Applications |
10.1016/j.eswa.2012.08.012 |
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Bottom-up urban water demand forecasting based on empirical data for individual water end uses or micro-components (e.g., toilet, shower, etc.) for different households of varying characteristics is undoubtedly superior to top-down estimates originating from bulk water metres that are currently performed. Residential water end-use studies partially enabled by modern smart metering technologies such as those used in the South East Queensland Residential End Use Study (SEQREUS) provide the opportunity to align disaggregated water end-use demand for households with an extensive database covering household demographic, socio-economic and water appliance stock efficiency information. Artificial neural networks (ANNs) provide the ideal technique for aligning these databases to extract the key determinants for each water end-use category, with the view to building a residential water end-use demand forecasting model. Three conventional ANNs were used: two feed-forward back propagation networks and one radial basis function network. A sigmoid activation hidden layer and linear activation output layer produced the most accurate forecasting models. The end-use forecasting models had R^2 values of 0.33, 0.37, 0.60, 0.57, 0.57, 0.21 and 0.41 for toilet, tap, shower, clothes washer, dishwasher, bath and total internal demand, respectively. All of the forecasting models except the bath demand were able to reproduce the means and medians of the frequency distributions of the training and validation sets. This study concludes with an application of the developed forecasting model for predicting the water savings derived from a citywide implementation of a residential water appliance retrofit program (i.e., retrofitting with efficient toilets, clothes washers and shower heads). |
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