The Battle of the Water Networks II (BWN-II)

The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis (WDSA 2012) conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multi-objective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems.Angela Marchi...Angus R. Simpson, Aaron C. Zecchin, Holger R. Maier...Christopher Stokes, Wenyan Wu, Graeme C. Dandy...et al

The Battle of the Water Networks II (BWN-II)

The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis (WDSA 2012) conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multi-objective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems.Angela Marchi...Angus R. Simpson, Aaron C. Zecchin, Holger R. Maier...Christopher Stokes, Wenyan Wu, Graeme C. Dandy...et al

Minimum transport-driven algorithm for water distribution network partitioning

This paper presents a novel algorithm driven by the minimization of the transport function for the partitioning of water distribution networks (WDNs) into district metered areas (DMAs). The algorithm is based on the linear programming (LP) embedded inside a multi-objective genetic algorithm, which enables engineering criteria, such as the minimization of the boundary pipes and the maximization of the uniformity of DMAs, to be considered in the partitioning. Furthermore, the application of the algorithm on the dual network topology based on segments and valves guarantees that configurations of DMAs that respect the real positions of isolation valves for WDN partitioning are obtained. After being described on a small WDN, it is successfully validated on a large size WDN, proving better performance than other algorithms in the scientific literature for the generation of engineeringly appealing DMA configurations, with almost identical hydraulic performance to the unpartitioned WDN

Exploring the effectiveness of clustering algorithms for capturing water consumption behavior at household level

As water scarcity becomes more prevalent, the analysis of urban water consumption patterns at the consumer level and the estimation of the corresponding water demand for water utility are expected to be among the top priorities of water companies in the near future. This study proposes a comprehensive methodology for water managers to achieve an efficient operation of urban water networks, by successfully detecting residential water consumption patterns corresponding to different household needs and behaviors. The methodology uses Self Organizing Maps as the main clustering algorithm in combination with K-means and Hierarchical Agglomerative Clustering. The objective is to create clusters in a literature dataset that includes water consumption from 21 customers located in Milford, Ohio, USA, for a 7-month period. Originally, water consumption data was recorded for every water use incident in the household, while for this analysis, the information is converted to half-hourly water consumption. Individual customers with similar consumption behavior are clustered and water-consumption curves are calculated for each cluster; these curves can be used by the water utility to obtain estimates of the spatio-temporal distribution of demand, thus giving insight into peak demands at different locations. Statistical indices of agreement are used to confirm a good agreement between the estimated and observed water use, when clustering is employed. The resulting curves show a clear improvement in capturing water consumption behavior at household level, when compared to corresponding curves obtained without clustering. This analysis offers water utilities an innovative solution that relies on real time data and uses data science principles for optimizing water supply and network operation and provides tools for the efficient use of water resources

Laboratory experiments on bed deposit scouring during flushing operations

The accumulation of sediments on the bottom of sewer channels is responsible for several hydraulic and environmental problems in urban drainage systems. For the removal of deposits, in the last decades many hydraulic devices based on the use of flushing waves have been successfully adopted in sewer systems instead of the more common and expensive mechanical devices. In this paper, the results of an experimental investigation for the analysis of the scouring effects of flushing waves on sediment bed deposits are presented. The experiments were performed in a laboratory flume using a simple flushing gate and considering different hydraulic conditions and bed deposit characteristics. The effects of successive flushing operations were evaluated in terms of bed profile evolution and sediment weights scoured out of the flume. The experimental data derived from the investigation can be taken into account for the validation of numerical models specifically developed for the simulation of the effects of flushing waves on sewer deposits

Dual topology for partitioning of water distribution networks considering actual valve locations

This paper proposes a general framework to adjust water distribution network (WDN) partitioning algorithms to account for the real positions of isolation valves. It is based on changing the reference WDN topology, on which partitioning algorithms typically operate. Specifically, the WDN topological description based on nodes and pipes must be replaced with a dual topology based on WDN segments and isolation valves. A generic partitioning algorithm can then be applied to the dual topology. As a result, DMAs are obtained by merging adjacent segments while inter-DMA boundary pipes are forced to be selected among the valve-fitted pipes that separate segments. This framework enables obtaining feasible WDN partitioning solutions, which do not need additional isolation valves to be installed. The applications of the novel framework to three WDN partitioning algorithms prove its effective applicability in one explicatory WDN and two WDNs of the real world

Novel Comprehensive Approach for Phasing Design and Rehabilitation of Water Distribution Networks

Traditionally, the design and the rehabilitation of water distribution networks (WDNs) have been addressed as separate problems. Here, a comprehensive approach to address both the design and rehabilitation of WDNs is proposed, considering the evolution of urban areas and the aging phenomena that typically involve WDNs. The search for the design and rehabilitation intervention schedule, in terms of installation of new, parallel, and replacement pipes, is addressed as a multiobjective optimization problem in which the solutions represent the trade-off between the system cost and its hydraulic resilience. A modified version of NSGA-II in combination with a pressure driven version of the EPANET 2 software was used to find optimal solutions. Application of the methodology to a literature case study indicates that it leads to a dramatic reduction in the failure costs, through a marginal increase in the investments in the short term, thanks to a farsighted intervention schedule. Also, a sensitivity analysis to the different aging phenomena was performed in order to understand which ones mostly affect the rehabilitation needs and long-term management of WDNs

Bottom-Up Generation of Water Demands to Preserve Basic Statistics and Rank Cross-Correlations of Measured Time Series

This paper presents a novel methodology for the generation of demand time series at water distribution network (WDN) users. After subdividing the day into an integer number of time steps with order of magnitude of 1 h, the methodology is based on two phases. First, it generates, for each user and for each time step of the day, demand time series of the first attempt, which are consistent with the measured time series in terms of mean, standard deviation, and skewness. This is done with a beta probability distribution with tunable bounds or with a gamma distribution with shift parameter. In the refinement phase, rank cross-correlations between users and at all temporal lags are imposed on the generated demand time series through a single Copula-based re-sort. The effectiveness of the methodology is proven in two real case studies with different numbers of users - namely, the literature case study of Milford, Ohio, and a novel Italian site. The demand time series obtained from the spatial aggregation of the generated user demand time series preserves very well mean and standard deviation of the measured aggregated demand time series. The preservation of skewness and temporal cross-correlations at all lags is very satisfactory. A procedure is also presented to reconcile the generated demand time series with demand pulses generated at fine time step, thus enabling reconstruction of demand at any time step

Comparison of bottom-up and top-down procedures for water demand reconstruction

none4noThis paper presents a comparison between two procedures for the generation of water demand time series at both single user and nodal scales, a top-down and a bottom-up procedure respectively. Both procedures are made up of two phases. The top-down procedure adopted includes a non-parametric disaggregation based on the K-nearest neighbours approach. Therefore, once the temporal aggregated water demand patterns have been defined (first phase), the disaggregation is used to generate water demand time series at lower levels of spatial aggregation (second phase). In the bottom-up procedure adopted, demand time series for each user and for each time step are generated applying a beta probability distribution with tunable bounds or a gamma distribution with shift parameter (first phase). Then, a Copula based re-sort is applied to the demand time series generated to impose existing rank cross-correlations between users and at all temporal lags (second phase). For the sake of comparison, two case studies were considered, both of which are related to a smart water network in Naples (Italy). The results obtained show that the bottom-up procedure performs significantly better than the top-down procedure in terms of rank-cross correlations at fine scale. However, the top-down procedure showed a better performance in terms of skewness and rank cross-correlation when the aggregated demands were considered. Finally, the level of aggregation in nodes was found to affect the performance of both the procedures considered.noneFiorillo D.; Creaco E.; Paola F.D.; Giugni M.Fiorillo, D.; Creaco, E.; Paola, F. D.; Giugni, M