Development of a leakage target setting approach for South Korea based on Economic Level of Leakage

Published13th Computer Control for Water Industry Conference, CCWI 2015Leakage has become a crucial issue that needs to be addressed effectively by water suppliers in terms of economic management of water systems. A target setting method based on the ELL (Economic Level of Leakage) calculation is proposed in this paper. The methodology applied is developed specifically for the South Korean context to select a minimum achievable level of NRW (Non-Revenue Water) and verify the appropriateness of the current target within existing financial constraints by using limited available data. This approach is focused on the derivation of the NRW control cost curve by using the newly developed cumulative method that minimizes data fluctuation and enhances the cost curve reliability. This has been applied to a case study by using data collected from the water supplier information system. The results obtained in this case study show significant outcomes in respect of both identification of an economically optimal target and prevention of unnecessary investment to meet this aim. This advance in leakage management allows water suppliers to select a rational target and manage their system economically and efficiently.This work has been funded and supported by K-water which is the public water company in South Kore

Resilience-based performance assessment of water-recycling schemes in urban water systems

Article16th Water Distribution System Analysis Conference, WDSA2014 — Urban Water Hydroinformatics and Strategic PlanningWater reuse schemes in urban water system are assessed in this paper against a number of hydraulic performance indicators. A city metabolism model, WaterMet2, is used to evaluate the performance of water reuse schemes. A multi-objective evolutionary algorithm is employed to identify Pareto optimal solutions for the following three objectives: resilience, reliability and total cost. The demonstration of the suggested approach on a real-world case study show the importance of using the resilience index for determining the appropriate schemes. The results suggest, in the case analysed here, the rainwater-harvesting scheme plays a significant role for improvement of resilience index.This work was carried out as part of the ‘TRansition to Urban water Services of Tomorrow’ (TRUST) project. The authors wish to acknowledge the European Commission for funding TRUST project in the 7th Framework Programme under Grant Agreement No. 265122

Using information-gap decision theory for water resources planning under severe uncertainty

PublishedJournal ArticleWater resource managers are required to develop comprehensive water resources plans based on severely uncertain information of the effects of climate change on local hydrology and future socio-economic changes on localised demand. In England and Wales, current water resources planning methodologies include a headroom estimation process separate from water resource simulation modelling. This process quantifies uncertainty based on only one point of an assumed range of deviations from the expected climate and projected demand 25 years into the future. This paper utilises an integrated method based on Information-Gap decision theory to quantitatively assess the robustness of various supply side and demand side management options over a broad range of plausible futures. Findings show that beyond the uncertainty range explored with the headroom method, a preference reversal can occur, i. e. some management options that underperform at lower uncertainties, outperform at higher levels of uncertainty. This study also shows that when 50 % or more of the population adopts demand side management, efficiency related measures and innovative options such as rainwater collection can perform equally well or better than some supply side options The additional use of Multi-Criteria Decision Analysis shifts the focus away from reservoir expansion options, that perform best in regards to water availability, to combined strategies that include innovative demand side management actions of rainwater collection and greywater reuse as well efficiency measures and additional regional transfers. This paper illustrates how an Information-Gap based approach can offer a comprehensive picture of potential supply/demand futures and a rich variety of information to support adaptive management of water systems under severe uncertainty. © 2012 Springer Science+Business Media Dordrecht.The authors are grateful to three anonymous referees for their detailed comments. Any errors remain our own. Brett Korteling is supported by the University of Exeter’s Climate Change and Sustainable Futures theme. South West Water are thanked for their generosity in terms of their time and data. Suraje Dessai was supported by the ARCC-Water project funded by EPSRC (EP/G061181/1) and the EQUIP project funded by NERC (NE/H003509/1)

Locating pipe bursts in a District Metered Area via online hydraulic modelling

PublishedComputing and Control for the Water Industry (CCWI2015): Sharing the best practice in water managementThis paper presents an online burst location method which extends the recently developed methodology [1] for online burst detection in Water Distribution Systems (WDS) at the District Metered Area (DMA) level. This is achieved by a combination of data algorithms that make use of flow and pressure residuals between the online hydraulic model predictions and corresponding WDS observations. The leak location methodology was tested on a series of simulated pipe burst events in a real-life UK DMA. The results obtained show that the new methodology is effective in determining burst locations in near real-time and satisfactorily estimates the burst flows.The authors are grateful to Engineering and Physical Sciences Research Council (EPSRC) and United Utilities (UU) including Mr T. Allen and UU hydraulic modelling team for providing the case study data and supporting financially the STREAM EngD project

A resilience-based methodology for improved water resources adaptation planning under deep uncertainty with real world application

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI on this record.Resilience of a water resource system in terms of water supply meeting future demand under climate change and other uncertainties is a prominent issue worldwide. This paper presents an alternative methodology to the conventional engineering practice in the UK for identifying long term adaptation planning strategies in the context of resilience. More specifically, a resilience based multi-objective optimization method is proposed that identifies Pareto optimal future adaptation strategies by maximizing a water supply system’s resilience (calculated as the maximum recorded duration of a water deficit period over a given planning horizon) and minimizing total associated costs, subject to meeting target system robustness to uncertain projections (scenarios) of future supply and demand. The method is applied to a real-world case study for Bristol Water’s water resource zone and the results are compared with those derived using a more conventional engineering practice in the UK, utilizing a least-cost optimization analysis constrained to a target reliability level. The results obtained reveal that the strategy solution derived using the current practice methodology produce a less resilient system than the similar costing solutions identified using the proposed resilience driven methodology. At the same time, resilience driven strategies are only slightly less reliable suggesting that trade-off exists between the two. Further examination of intervention strategies selected shows that the conventional methodology encourages implementation of more lower cost intervention options early in the planning horizon (to achieve higher system reliability) whereas the resilience-based methodology encourages more uniform intervention options sequenced over the planning horizon (to achieve higher system resilience).This work was financially supported by the UK Engineering and Physical Sciences Research Council, HR Wallingford and The University of Exeter through the STREAM Industrial Doctorate Centre. We thank Bristol Water for allowing the use of their data and information, which is available from their publicly available water resources management plan

Achieving regional scale surface water management using synthetic stream networks

This is the final version.Data availability: The catchment database is available to academics and water management professionals through contacting the author.Engineering and Physical Sciences Research Council (EPSRC)Natural Environment Research Council (NERC

Online modelling of water distribution system using Data Assimilation

PublishedConference Proceeding12th International Conference on Computing and Control for the Water Industry, CCWI2013This paper applies Data Assimilation (DA) methods to a Water Distribution System Model to improve the realtime estimation of water demand, and hydraulic system states. A time series model is used to forecast water demands which are used to drive the hydraulic model to predict the future system state. Both water demands and water demand model parameters are corrected via DA methods to update the system state. The results indicate that DA methods improved offline hydraulic modelling predictions. Of the DA methods, the Ensemble Kalman Filter outperformed the Kalman Filter in term of updating demands and water demand model parameters. © 2013 The Authors.The authors are grateful to United Utilities (UU), Mr D. Clucas, Mr T. Allen, Mr N. Croxton and UU hydraulic modelling team for providing the case study data and supporting financially the STREAM EngD project

Use of metamodels in real-time operation of water distribution systems

Published16th Water Distribution System Analysis Conference, WDSA2014 — Urban Water Hydroinformatics and Strategic PlanningThis paper presents a methodology for real-time pump scheduling in water distribution system. The methodology uses an optimizer linked to other two modules: one to predict the hydraulic behavior of the system and another to forecast the demands. A metamodel is used instead of a traditional hydraulic simulator to speed up relevant computations, i.e. evaluations of large number of candidate pump schedules generated during the optimization process. The methodology presented is applied to a real-life water distribution system in Brazil. The results obtained show that the use of metamodel can generate low cost pump schedules in a computationally fast manner.The authors acknowledge the support from the São Paulo Research Foundation (FAPESP), from the Coordination for the Improvement of Higher Education (CAPES) and from the Brazilian Scientific and Technological Development Council (CNPq) for providing the PhD's scholarship and Grant to the second author, and also from the Araraquara’s Autonomous Department of Water and Sewage (DAAE-Araraquara, SP, Brazil) for providing data and assistance through the agreement between the company and the University of São Paulo

Investigating prior parameter distributions in the inverse modelling of water distribution hydraulic models

PublishedJournal Article© 2014 Journal of Mechanical Engineering. All rights reserved. Inverse modelling concentrates on estimating water distribution system (WDS) model parameters that are not directly measurable, e.g. pipe roughness coefficients, which can, therefore, only be estimated by indirect approaches, i.e. inverse modelling. Estimation of the parameter and predictive uncertainty of WDS models is an essential part of the inverse modelling process. Recently, Markov Chain Monte Carlo (MCMC) simulations have gained in popularity in uncertainty analyses due to their effective and efficient exploration of posterior parameter probability density functions (pdf). A Bayesian framework is used to infer prior parameter information via a likelihood function to plausible ranges of posterior parameter pdf. Improved parameter and predictive uncertainty are achieved through the incorporation of prior pdf of parameter values and the use of a generalized likelihood function. We used three prior information sampling schemes to infer the pipe roughness coefficients of WDS models. A hypothetical case study and a real-world WDS case study were used to illustrate the strengths and weaknesses of a particular selection of a prior information pdf. The results obtained show that the level of parameter identifiability (i.e. sensitivity) is an important property for prior pdf selection.We are obliged to Jasper A. Vrugt and Cajo ter Braak for providing the code of the DREAM(ZS) algorithm and graphical post-processing software

Robust staged development of water supply systems

This paper presents a new methodology for optimal staged development of water supply systems that ensures robust and sustainable solutions. This problem is formulated as a multi-objective optimisation problem under uncertainty with objectives being the minimisation of average present value of intervention costs and greenhouse gas emissions, and the maximisation of supply robustness. The above methodology was validated and demonstrated on southern portion of the regional water supply system of Adelaide. The results obtained illustrate the importance of identifying optimal staged solutions to ensure robustness and sustainability of water supply into uncertain long-term future