A DSS generator for multiobjective optimisation of spreadsheet-based models

Copyright © 2011 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Environmental Modelling & Software. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Environmental Modelling & Software Vol. 26 (2011), DOI: 10.1016/j.envsoft.2010.11.004Water management practice has benefited from the development of model-driven Decision Support Systems (DSS), and in particular those that combine simulation with single or multiple-objective optimisation tools. However, there are many performance, acceptance and adoption problems with these decision support tools caused mainly by misunderstandings between the communities of system developers and users. This paper presents a general-purpose decision-support system generator, GANetXL, for developing specific applications that require multiobjective optimisation of spreadsheet-based models. The system is developed as an Excel add-in that provides easy access to evolutionary multiobjective optimisation algorithms to non-specialists by incorporating an intuitive interactive graphical user interface that allows easy creation of specific decision-support applications. GANetXL’s utility is demonstrated on two examples from water engineering practice, a simple water supply reservoir operation model with two objectives and a large combinatorial optimisation problem of pump scheduling in water distribution systems. The two examples show how GANetXL goes a long way toward closing the gap between the achievements in optimisation technology and the successful use of DSS in practice.Engineering and Physical Sciences Research Council (EPSRC

Optimizing Operating Rules Of Multiple Source Water Supply Systems In Terms Of System Reliability And Resulting Operating Costs: Survey Of Simulation-Optimization Modeling Approaches Based On General Purpose Tools

Management of a water supply system from the point of view of the conjunctive use of water sources is a very complex problem whose solution is not just obtained using analytical models but also through a negotiation process among stakeholders and in which Public Bodies have a main role. For these reasons, this problem has been addressed using conservative approaches based on simulation models or simulation – linear optimization models parameterized using few parameters. These approaches have certain strengths but also certain drawbacks or constraints. In general these conservative approaches are already covered by existing generalized modelling tools (i.e. Aquator, Oasis and Riverware) that may be used to estimate a solution through a longer or shorter trial and error process. However, these conservative approaches and the corresponding generalized modelling tools have drawbacks and constraints when dealing with certain complexities of water supply systems (i.e.: non-linearity, uncertainty or stochastic nature) that may prevent them of finding an optimal solution. Therefore, a functionality that current modelling systems are starting to offer to overcome this drawback is the capacity to be linked with external software modules mainly implementing accurate and complex optimization methods (i.e.: Evolutionary Algorithms / SolveXL tool). This paper identifies and tests suitable Simulation-Optimization approaches found in existing Generalized Modeling Tools for optimizing operating rules of multiple source water supply systems in terms of system reliability and resulting operating costs: a special focus on Genetic Algorithms is considered. The main purpose is to find out whether these approaches are already covering the decision support needs of managers, Public Bodies or other stakeholders involved in the operation of these systems, or ‘ad-hoc’ tools may be needed. This process leads to identify strengths and weaknesses of these modeling approaches found in existing Generalized Modeling Tools

Optimizing operating rules of multiple source water supply systems in terms of system reliability and resulting operating costs

This Presentation is brought to you for free and open access by the City College of New York at CUNY Academic Works. It has been accepted forinclusion in International Conference on Hydroinformatics by an authorized administrator of CUNY Academic Works. For more information, pleasecontact [email protected] and operation of a multiple-objective multisource water supply system from the point of view of the conjunctive use of water sources is a very complex problem whose solution is not just obtained using analytical models but also through a negotiation process among stakeholders and in which Public Bodies have a main role. For these reasons, this problem has been addressed using conservative approaches based on simulation models or simulation–linear optimization models parameterized using few parameters which, in general, are already covered by existing generalized modelling tools using a longer or shorter trial and error process. However, these conservative approaches have drawbacks and constraints when dealing with certain complexities of water supply systems (i.e.: non-linearity, uncertainty or stochastic nature) that may prevent them of finding an optimal solution. This paper identifies and tests suitable simulation-optimization approaches found in existing generalized modeling tools for optimizing operating rules of multisource water supply systems in terms of system guarantee and resulting operating costs. The main purpose is to find out whether these approaches are already covering the decision support needs of managers, Public Bodies or other stakeholders involved in the operation of these systems, or ‘ad-hoc’ tools may be needed.Peer ReviewedPostprint (published version

Using a systematic, multi-criteria decision support framework to evaluate sustainable drainage designs

Open Access journalCopyright © 2013 The Authors. Published by Elsevier Ltd.12th International Conference on Computing and Control for the Water Industry, CCWI2013The conventional drainage design approach does not address sustainability issues. Moving forward, an alternative approach using green infrastructures is recommended. In addition to flow and flood management provided by the conventional methods, green infrastructures can bring multiple benefits such as increased amenity value and groundwater recharge. Unlike the traditional practice, the new approach lacks supporting technical references and software. Stakeholders are discouraged by the uncertainty of performance and costs associated with green infrastructures. We aim to bridge this knowledge gap by providing a systematic decision support framework. This paper provides an overview of the evaluation framework with some application examples

Optimal Design Approach of Solar Powered Rural Water Distribution Systems in Developing Countries

This is the author accepted manuscript.In many rural parts of the developing world reliable access to clean water and electrical power is constrained. In this study, methods of integrating estimations of power outputs from solar photovoltaic arrays into gravity-fed water distribution network modelling are investigated. The effects of powering a rural water distribution system that is replenished with groundwater pumps that use solar power, and the effect of this on other network design decisions, are investigated. A rural community of an estimated 2,800 people with 28 standpipes from a borehole was chosen to develop the optimisations. The water storage tank and pipework were the focus on the water distribution system. EPANET and generic algorithms were used to run network optimisation simulations of: water tank location, elevation and volume; pipe diameter and configuration; and optimal system design in terms of cost. Different scenarios were included producing supply, demand and required water storage curves, which could have practical application for rural water distribution system design. Indicative costs for theoretical water distribution networks for rural communities in The Gambia were generated

A multi-objective optimisation model for sewer rehabilitation considering critical risk of failure

Copyright © 2012 IWA Publishing. The definitive peer-reviewed and edited version of this article is published in Water Science & Technology, Vol 66 No 11, pp. 2410–2417 (2012), DOI: 10.2166/wst.2012.393 and is available at www.iwapublishing.com.A unique methodology for the optimal specification of sewer rehabilitation investment is presented in this paper. By accounting for the critical risk of asset failure, this methodology builds on previously successful work which explored the application of multi-objective optimisation tools to assist engineers with the specification of optimal rehabilitation strategies. The conventional sewerage rehabilitation specification process relies on the expertise of professional engineers to manually evaluate CCTV inspection information when determining the nature and extent of the rehabilitation solution. This process is not only tedious and subjective but it has no quantifiable means of identifying optimal solutions or possible combinations of optimal solutions in the delivery of catchment wide rehabilitation programmes. Therefore, the purely manual process of sewer rehabilitation design leaves a number of unanswered questions, such as: (1) Does the solution offer the greatest structural benefit to the network? (2) Is the solution the most cost-effective solution available? (3) Does the solution most greatly reduce the risk of critical asset failure? The application of a multi-objective genetic algorithm optimisation model, coupled with an enhanced critical risk methodology, has successfully answered these questions when applied to a case study data set provided by South West Water (UK)

An Integrated Optimal Approach for Solar Powered Rural Water Distribution Systems in the Gambia

This is the final version. Available on open access from Scientific Research Publishing via the DOI in this recordIn the Gambia and across sub-Saharan Africa, reliable access to clean water and electrical power is constrained. As many rural water supply systems are already built, enhanced understanding of efficiencies and optimisation is required. Here, methods of integrating estimations of power outputs from solar photovoltaic arrays into gravity-fed water distribution network modelling are investigated. The effects of powering a rural water distribution system that is replenished with groundwater pumps that use solar power are investigated, along with the effect of this on other network design decisions. The water storage tank and pipework of a rural community with an estimated 2800 people and 28 standpipes from a borehole was selected. EPANET modelling software and genetic algorithms were used to run network optimisation simulations of: water tank location, elevation and volume; pipe diameter and configuration; and optimal system design in terms of cost. Different scenarios included producing supply, demand and required water storage curves, which could have practical application for rural water distribution system design. Indicative costs for theoretical water distribution networks will be useful for decision makers and planners

Extending EPANET capabilities with Add-In Tools

[EN] EPANET is probably the most widespread model for water distribution network (WDN). More than twenty years after its appearance, it has become a global reference both for hydraulic and quality analysis of water networks. In 2000, EPANET 2 appears, which includes as most important computational feature a new Toolkit. This toolkit was a library of functions allowing the modification of network data and reading results without access to the appropriate files. Over time, the use of this library has been the communication protocol for every application developers who use the method propose by Todini and Pilati to analyze the behavior of WDN. This library also provides interface tools that allow the execution of a simulation from an external application, as long as the network characteristics had been previously defined. This paper presents a change in the original EPANET model, including a new menu in the graphical user interface (GUI). This menu allows users to set up a personal collection of Add-In tools, which use both project data and simulation results. These tools can be customized and allows to extend the analysis capability of EPANET. All of them can access EPANET functions through the Toolkit and were developed by the authors during the Spanish translation of EPANET, taking into account the homologous Add-in tools developed for SWMM model. As an example of the operation and capabilities of this new menu, several applications integrated as EPANET add-in tools are presented. These tools perform tasks such as importing data network from both CAD and GIS systems, the design of WDNs using genetic algorithms, automatic assignment of initial water quality to network nodes; the skeletonization of a network or optimization of pumping schedule in the network in order to achieve a minimum energy cost.Iglesias Rey, PL.; Martínez-Solano, FJ.; Ribelles-Aguilar, J. (2017). Extending EPANET capabilities with Add-In Tools. Procedia Engineering. 186:626-634. doi:10.1016/j.proeng.2017.03.279S62663418

An optimised total expenditure approach to sewerage management

Copyright © 2014 Thomas Telford Ltd.It is generally accepted by Ofwat, the water industry regulator for England and Wales, that the current investment planning system whereby capital and operational expenditure are accounted for separately is complex and burdensome. In a move towards realising a total expenditure approach, a previously successful sewer rehabilitation optimisation model has been adapted to provide a mechanism for users to evaluate the trade-offs that exist between the capital and operational benefits associated with different sewer rehabilitation schemes. A series of geographic information system tools has been integrated within the model to help prioritise high-benefit sewer rehabilitation schemes by evaluating the potential serviceability improvements that can be realised in addition to the purely structural condition improvements. As a result, the new sewer rehabilitation model can be referred to as a strategic decision support tool that is capable of helping sewerage engineers and planners in the evaluation of different intervention programmes of work. The benefits of adopting this approach are demonstrated in a UK sewerage case study that uses a multi-objective genetic algorithm to consider the three-way trade-off that exists between minimising investment cost against maximising asset life (capital benefit) compared with proactively addressing serviceability problems (operational benefit).EPSRC (Engineering and Physical Sciences Research Council

Optimal operation of a multi-quality water distribution system with changing turbidity and salinity levels in source reservoirs

Impact of water quality conditions in sources on the optimal operation of a regional multiquality water distribution system is analysed. Three operational objectives are concurrently minimised, being pump energy costs, turbidity and salinity deviations at customer nodes. The optimisation problem is solved using GANetXL (NSGA-II) linked with EPANet. The example network incorporates scenarios with different water quality in sources. It was discovered that two types of tradeoffs, competing and non-competing, exist between the objectives and that the type of tradeoff is not unique between a particular pair of objectives across scenarios. The findings may be used for system operational planning