Accounting for Local Water Storages in Assessing WDN Supply Capacity

AbstractIn many real WDNs, as in the Mediterranean area, customers are traditionally supplied by local water storages (i.e. roof or basement tanks) fed from the top by service pipes of the urban WDN through volume-controlled orifices. The present contribution shows that the prediction of WDN water supply capacity achieved by a model accounting for the filling/emptying of local tanks, is different from both classical demand-driven analysis and the pressure-driven analysis based on Wagner's demand-pressure relationship at each node. The WDNetXL system (www.hydroinformatics.it) is used to perform multiple simulation runs to assess WDN capacity under increasing demand scenarios

Supporting Decision on Energy vs. Asset Cost Optimization in Drinking Water Distribution Networks

AbstractOne of the challenges for water utilities is the optimal asset design (i.e. maximum power of pump systems, tank volumes and pipe diameters) of water distribution networks (WDN) while optimizing operational efficiency (i.e. energy consumption and cost). Besides the classical minimization of capital cost while providing sufficient supply service, the operational sustainability is an emerging issue. As the reduction of each component of capital and energy costs are conflicting with each other, the optimization problem is multi-objective. This work presents the study of the robustness of solutions of the Pareto set as a further element to support the decision

Operational and Tactical Management of Water and Energy Resources in Pressurized Systems: Competition at WDSA 2014

Optimal management of water and energy resources worldwide is a basis for environmental and socioeconomic sustainability in urban areas, which has become even more relevant with the advent of the smart and water sensitive city paradigm. In water distribution networks (WDNs) water resource management is concerned with increased efficiency, which is primarily related to the reduction of leakages, whereas energy management refers to optimal pump, valve, and source scheduling strategies considering the hydraulic system requirements. These management goals require planning of asset renewal and improvement works in the short time (operational) and medium time (tactical) horizons, considering the financial sustainability of relevant actions. The battle of background leakage assessment for water networks (BBLAWN) was designed as a competition held at the 16th Water Distribution Systems Analysis Conference, in Bari (Italy) in 2014 (WDSA), to address the aforementioned management goals. The teams taking part in the BBLAWN were asked to develop a methodology for both reducing real water losses and saving energy in a real WDN considering the possibility of asset renewal and strengthening. Fourteen teams from academia, research centers, and industry presented their solutions at a special session of the WDSA 2014 conference. This paper briefly describes the BBLAWN and presents one of the solutions provided by the organizers to illustrate the ideas and challenges embedded in the posed problem. The overview of the solutions provided by the participants shows that management decisions need to be supported by engineering judgment and with tools that combine computationally effective multiobjective optimization and hydraulic models capable of assessing pressure-dependent background leakages.Italian Scientific Research Program of National Interest PRIN-2012Italian Ministry of Education, University and Researc

INPUT SELECTION BY EPR-MOGA

The growing availability of field data, from information and communication technologies (ICTs) in "smart'' urban infrastructures, allows data modeling to understand complex phenomena and to support management decisions. Among the analyzed phenomena, those related to storm water quality modeling have recently been gaining interest in the scientific literature. Nonetheless, the large amount of available data poses the problem of selecting relevant variables to describe a phenomenon and enable robust data modeling. This paper presents a procedure for the selection of relevant input variables using the multi-objective evolutionary polynomial regression (EPR-MOGA) paradigm. The procedure is based on scrutinizing the explanatory variables that appear inside the set of EPR-MOGA symbolic model expressions of increasing complexity and goodness of fit to target output. The strategy also enables the selection to be validated by engineering judgement. In such context, the multiple case study extension of EPR-MOGA, called MCS-EPR-MOGA, is adopted. The application of the proposed procedure to modeling storm water quality parameters in two French catchments shows that it was able to significantly reduce the number of explanatory variables for successive analyses. Finally, the EPR-MOGA models obtained after the input selection are compared with those obtained by using the same technique without benefitting from input selection and with those obtained in previous works where other data-modeling techniques were used on the same data. The comparison highlights the effectiveness of both EPR-MOGA and the input selection procedure

New concepts and tools for pipe network design

Water Distribution Network design has been traditionally approached as a cost minimization problem, constrained by some additional restrictions intended to ensure an acceptable level of customer service. Although the ideas have existed for same time, it was only recently that various researchers developed new network optimization approaches trying to address the minimization of design costs, while maximizing the benefits through some other performance indicators assessment in a risk-based scenario. Unfortunately, network simulation is still performed within a demand-driven context, even when reliability is considered among the benefits, and leakages are given as a constant percentage of nodal demands instead of being computed as a function of pipe pressure. This article introduces a more realistic approach to network design and simulation, performed using pressure-driven leakages employing a recently developed simulation model. Thus, the design procedure is conceived as multi-objective optimization, performed considering the minimization of pipe cost and together with total network leakage flow. The approach was tested on a small-size Italian real network which supplies an industrial area, and on a simpler network that yielded some interesting observations about the proposed paradigm

Estimating Leakages in Water Distribution Networks Based Only on Inlet Flow Data

The estimate of current real losses in water distribution networks (WDN) is crucial to plan investments for rehabilitation, assess the rise of leakage over time, and possibly drive procedures for failure identification and repair. However, many WDNs worldwide do not have flow/pressure monitoring within the system yet, and the inlet water volume or flowrate is the only recorded data. Developing reliable procedures to estimate real losses in such circumstances is essential to assess the leakage phenomenon and eventually drive the upgrade of existing monitoring systems. This work proposes a simple bottom-up methodology to estimate leakage using WDN inflow data series while only exploiting the seasonal fluctuation of water consumptions. It resorts to a data-assimilation strategy whose formulation is consistent with the physical behavior of WDNs and requires the estimate of only a few numerical parameters. Additionally, the methodology allows the estimation of the user’s daily and night water consumptions, thus being useful to verify or integrate other leakage estimate methods. The methodology is discussed and demonstrated on both synthetic and real WDN

Battle of background leakage assessment for Water Networks (BBLAWN) at WDSA conference 2014

16th Water Distribution System Analysis Conference, WDSA2014 — Urban Water Hydroinformatics and Strategic PlanningThe Battle of Background Leakage Assessment for Water Networks (BBLAWN) is the fifth in a series of "Battle Competitions" dating back to the Battle of the Water Networks (BWN) in 1985 and, more recently, the Battle of the Water Sensor Networks (BWSN) in 2006; the Battle of the Water Calibration Networks (BWCN) in 2010 and the Battle of the Water Networks Design (BWN-II) in 2012. The BBLAWN asks for a design methodology for reducing water losses due to background leakages in a real water distribution system. The results have been presented at a special session of the 16th Water Distribution Systems Analysis Conference, held in Bari, Italy in July 2014, where 14 teams from academia, research centers and companies presented their solutions to the problem in hand