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This paper presents the head-drop method for the modeling of pressure regulation devices in the steady-state simulation of water distribution networks (WDNs). The method is based on addition of device-associated head drops to the source term of pipe energy-balance equations. Head drops and device statuses (active, open, and closed) are updated during the iterations of WDN resolution based on the values of pipe water discharge and of head at pipe end nodes. The proposed method is easily implementable in any WDN resolution algorithm for both local and remote regulation of pressure reducing valves (PRVs) and variable speed pumps (VSPs). The application to four case studies proved the efficiency and robustness of the method, which will be implemented in the hydraulic engine of Smart Water Network Protection and Partitioning (SWANP) software. [ABSTRACT FROM AUTHOR]

This paper presents a novel algorithm with improved convergence and robustness for the pressure-driven modeling of water distribution networks (WDNs), to be implemented as hydraulic engine in the fourth release of the SWANP version 4.0 software. The innovative approach is based on increasing the order of convergence, which is quadratic for algorithms obtained from the Newton Raphson linearization of the equations for WDN resolution. As an example, the cubic order of convergence is obtained by evaluating system matrices at the generic iteration in a more refined way to account for the curvature of the hyperplane associated with the system in the direction of the Newton Raphson step. To show the benefits of the methodology, a third-order algorithm is constructed and compared with a traditional second-order. Both algorithms are based on the direct pressure-driven formulation expressing outflows as a function of service pressure and are equipped with the dampening of the Newton Raphson step. Applications on two case studies of different size, in which challenging pressure-driven conditions are created through demand amplification and segment isolation scenarios, prove that the methodology always reduces the total number of iterations required for convergence and the application of the step dampening. Overall, the results also show that the more stable convergence behavior is accompanied by an appreciable reduction in computation times. Further analyses proved that the third-order algorithm has similar convergence properties to algorithms based on the inverse pressure-driven formulation recently proposed in the scientific literature and can therefore be considered as a valid alternative to these algorithms. [ABSTRACT FROM AUTHOR]

This document is a closure to a paper titled "Head-Drop Method for the Modeling of Pressure Reducing Valves and Variable Speed Pumps in Water Distribution Networks." It addresses comments and concerns raised by discussers regarding the head drop value under open pressure reducing valve (PRV) conditions. The writers acknowledge the error in the original paper and clarify that the assigned value should be 0. They also discuss the head loss associated with open PRV conditions and provide tables describing the PRV and pressure-sustaining valve (PSV) status and head drop values. The closure concludes by noting that conflicting PRV and PSV situations are rare in real-world water distribution networks. The report, authored by Enrico Creaco, Armando Di Nardo, Michele Iervolino, and Giovanni Santonastaso, is a valuable resource for library patrons conducting research on this topic. [Extracted from the article]

The positioning of quality detection points as well as the frequency of sampling is a crucial aspect for the implementation of Water Safety Plans (WSPs), which have been proposed worldwide to ensure water quality and to minimize the risk from contamination in water distribution networks (WDNs). In this regard, some international legislations and best practices about quality of drinking water suggest very fine sampling frequencies, but they do not specify where the detection points should be located in a WDN. In this paper, three different approaches, based on empiricism, optimization and topology, respectively, were applied to locate detection quality points in a WDN. The comparison highlighted that empirical approach commonly adopted by water utility practitioners is unsatisfactory. The optimization-based approach, although performing significantly better, is difficult to apply, since it requires a calibrated hydraulic model. The topological approach, based on the use of the betweenness centrality and not requiring any hydraulic information and simulation, proves to be effective, and it can be easily adopted by water utilities to identify the location for quality detection points, due to its simplicity compared with the optimization-based approach. [ABSTRACT FROM AUTHOR]

Permanent partitioning represents one of the more effective approaches for an innovative management of water distribution networks (WDNs) because it allows simplification of the network control defining small subsystem defined as a district meter area (DMA) in which it is simpler to compute water balance, to achieve pressure management and to check water quality. The design of permanent water network partitioning (WNP) is very difficult to apply to large water networks using traditional approaches based on empirical considerations and trial and errors techniques. Recently, the authors developed the software SWANP that allows definition automatically of the number and dimension and shape of a DMA using different innovative heuristic optimization procedures. In this paper a novel release 3.5 of SWANP is presented that implements novel algorithms, based on social network theory for the clustering phase and a genetic multiobjective for the dividing phase, to automatically design DMAs of a real, large water network in Alcalá de Henares, Spain. [ABSTRACT FROM AUTHOR]

This document is a correction notice for the article titled "Head-Drop Method for the Modeling of Pressure Reducing Valves and Variable Speed Pumps in Water Distribution Networks" by Enrico Creaco, Armando Di Nardo, Michele Iervolino, and Giovanni Santonastaso. The corrections involve errors in Tables 1 and 2 of the published paper, but the correct values were used in the calculations. The corrected tables are provided in the erratum. The purpose of this erratum is to preserve the accuracy of the published version of the article. [Extracted from the article]

Water distribution systems (WDSs) today are expected to continuously provide clean water while meeting users demand, and pressure requirements. To accomplish these targets is not an easy task due to extreme weather events, operative accidents and intentional attacks; as well as the progressive deterioration of the WDS assets. Therefore, water utilities should be ready to deal with a range of disruption scenarios such as abrupt variations on the water demand e.g. caused by pipe bursts or topological changes in the water network. This paper presents a novel methodology to automatically split a WDS into self-adapting district metered areas (DMAs) of different size in response to such scenarios. Complex Networks Theory is proposed for creating novel multiscale network layouts for a WDS. This makes it possible to automatically define the dynamic partitioning of WDSs to support further DMA aggregation / disaggregation operations. A real, already partitioned, water utility network shows the usefulness of an adaptive partitioning when the network is affected by an abnormal increase of the peak demand of up to 15%. The dynamic DMA reuses the assets of the static partitioning and, in this case, up to the 82% of resilience is restored using 94% of the assets already installed. The results also show that the overall computational and economic management costs are reduced compared to the static DMA partition while the hydraulic performance of the WDS is simultaneously preserved. [ABSTRACT FROM AUTHOR]

Robustness of water distribution networks is related to their connectivity and topological structure, which also affect their reliability. Flow entropy, based on Shannon's informational entropy, has been proposed as a measure of network redundancy and adopted as a proxy of reliability in optimal network design procedures. In this paper, the scaling properties of flow entropy of water distribution networks with their size and other topological metrics are studied. To such aim, flow entropy, maximum flow entropy, link density and average path length have been evaluated for a set of 22 networks, both real and synthetic, with different size and topology. The obtained results led to identify suitable scaling laws of flow entropy and maximum flow entropy with water distribution network size, in the form of power-laws. The obtained relationships allow comparing the flow entropy of water distribution networks with different size, and provide an easy tool to define the maximum achievable entropy of a specific water distribution network. An example of application of the obtained relationships to the design of a water distribution network is provided, showing how, with a constrained multi-objective optimization procedure, a tradeoff between network cost and robustness is easily identified. [ABSTRACT FROM AUTHOR]

Cities depend on multiple heterogeneous, interconnected infrastructures to provide safe water to consumers. Given this complexity, efficient numerical techniques are needed to support optimal control and management of a water distribution network (WDN). This paper introduces a holistic analysis framework to support water utilities on the decision making process for an efficient supply management. The proposal is based on graph spectral techniques that take advantage of eigenvalues and eigenvectors properties of matrices that are associated with graphs. Instances of these matrices are the adjacency matrix and the Laplacian, among others. The interest for this application is to work on a graph that specifically represents a WDN. This is a complex network that is made by nodes corresponding to water sources and consumption points and links corresponding to pipes and valves. The aim is to face new challenges on urban water supply, ranging from computing approximations for network performance assessment to setting device positioning for efficient and automatic WDN division into district metered areas. It is consequently created a novel tool-set of graph spectral techniques adapted to improve main water management tasks and to simplify the identification of water losses through the definition of an optimal network partitioning. Two WDNs are used to analyze the proposed methodology. Firstly, the well-known network of C-Town is investigated for benchmarking of the proposed graph spectral framework. This allows for comparing the obtained results with others coming from previously proposed approaches in literature. The second case-study corresponds to an operational network. It shows the usefulness and optimality of the proposal to effectively manage a WDN. [ABSTRACT FROM AUTHOR]

Water Network Partitioning (WNP) improves water network management, simplifying the computation of water budgets and, consequently, allowing the identification and reduction of water losses. It is achieved by inserting flow meters and gate valves into a network which has been previously clustered into subsystems. Generally, the procedures are subdivided into two main steps: the clustering and partitioning phases. At first, network nodes are assigned to each cluster and then the appropriate pipes are selected, in which flow meters or gate valves are to be inserted. In this paper, an improved multilevel-recursive bisection algorithm was used to achieve network clustering. To better allocate the hydraulic devices, the partitioning phase was carried out through the minimization of a novel, multi-objective function, taking simultaneous account of energy and economic aspects. The aim is to define a solution that occupies a minimum possible number of flow meters, simplifying the water budget computation, preserving the hydraulic performances, and minimizing the capital and the operational costs. The procedure was tested on an extensive and real Mexican network, providing different optimal solutions and a smart Decision Support System (DSS) (based on visual diagrams and innovative energy, robustness, and balancing metrics). [ABSTRACT FROM AUTHOR]

The availability on the market of remote control valves for water distribution systems allows a more flexible implementation of the “divide and conquer” paradigm, that consists in dividing large networks into smaller district meter areas defining a water network partitioning (WNP), aiming at controlling water balance, pressure levels and water quality protection. The positioning of gate valves is carried out using optimization approaches to guarantee the network reliability that can be significantly reduced by WNP owing to the closure of several pipes by means of gate valves, decreasing topologic and energy redundancy. Anyway, starting from the optimal positioning of remote controlled gate valves, obtained with SWANP software, the paper investigates the effectiveness of dynamic control, in order to face hydraulic failure in fire estinguishment. The proposed methodology, based on heuristic optimization algorithm, finds the optimal layouts minimizing the number of valves to be opened and maximizing the system performance. The study highlights the advantages of adaptively reconfigurable networks starting from a partitioned system, confirming that a dynamic control represents a significant improvement for smart water networks. [ABSTRACT FROM AUTHOR]

The partitioning of water distribution system is a complex process achieved defining network clusters arranged in sectors, with the complete isolation of clusters through gate valves, or arranged in districts, inserting both gate valves and flow meters. The process is generally subdivided in two phases: clustering, aimed to define the shape and dimension of network clusters, and partitioning, aimed to select pipes in which to insert flow meters or gate valves. In this paper, different clustering procedures based on social network community detection and on graph partitioning algorithms, were compared using a real water system and a large battery of performance indices. [ABSTRACT FROM AUTHOR]

This paper proposes a new methodology for the optimal design of water network sectorization, which is an essential technique for improving the management and security of multiple-source water supply systems. In particular, the network sectorization problem under consideration concerns the definition of isolated district meter areas, each of which is supplied by its own source (or sources) and is completely disconnected from the rest of the water system through boundary valves or permanent pipe sectioning. The proposed methodology uses graph theory principles and a heuristic procedure based on minimizing the amount of dissipated power in the water network. The procedure has been tested on two existing water distribution networks (WDNs) (in Parete, Italy and San Luis Rio Colorado, Mexico) using different performance indices. The simulation results, which confirmed the effectiveness of the proposed methodology, surpass empirical trial-and-error approaches and offer water utilities a tool for the design of multiple-source WDNs in isolated districts. [ABSTRACT FROM AUTHOR]

The management of existing water supply networks can be substantially improved by permanent water district metering (WDM) which is one of the most efficient techniques for water loss detection and pressure management. However, WDM may compromise water system performance, since some pipes are usually closed to delimit districts in order not to have too many metering stations, to decrease costs and simplify water balance. This may reduce the reliability of the whole system and not guarantee the delivery of water at the different network nodes. In practical applications, the design of district meter areas (DMAs) is generally based on empirical approaches or on limited field experiences. In this work a design support methodology (DSM) is proposed, which helps to identify the position of flow meters and of boundary valves needed to define permanent DMAs. The DSM is based on graph theory and is applied to a test case. [ABSTRACT FROM AUTHOR]

Finally, the last two papers hosted in the Special Issue were not fully aligned to the topic of water distribution networks, but they are very interesting in the more general paradigm of smart networks and big data collection with innovative smart sensors. This Editorial presents the paper collection of the Special Issue (SI) on Smart Urban Water Networks. Further, the more advanced challenges delineated in the SI are the topic regarding real-time control and operation of water systems, also with the possibility to activate dynamic changes in the network operation using smart devices controlled in real-time (e.g., regulation valves, on-off valves). In the more general framework of Industry 4.0, the recent development of Internet of Things (IoT) technologies applied to smart grids opens further novel opportunities in the management of water network systems and beyond. [Extracted from the article]

This paper proposes a combined management strategy for monitoring water distribution networks (WDNs). This strategy is based on the application of water network partitioning (WNP) for the creation of district metered areas (DMAs) and on the installation of sensors for water quality monitoring. The proposed methodology was tested on a real WDN, showing that boundary pipes, at which flowmeters are installed to monitor flow, are good candidate locations for sensor installation, when considered along with few other nodes detected through topological criteria on the partitioned WDN. The option of considering only these potential locations, instead of all WDN nodes, inside a multi-objective optimization process, helps in reducing the search space of possible solutions and, ultimately, the computational burden. The solutions obtained with the optimization are effective in reducing affected population and detection time in contamination scenarios, and in increasing detection likelihood and redundancy of the monitoring system. Last but most importantly, these solutions offer benefits in terms of management and costs. In fact, installing a sensor alongside the flowmeter present between two adjacent DMAs yields managerial advantages associated with the closeness of the two devices. Furthermore, economic benefits due to the possibility of sharing some electronical components for data acquisition, saving, and transmission are derived. [ABSTRACT FROM AUTHOR]

Water Distribution Networks (WDNs) can be regarded as complex networks and modeled as graphs. In this paper, Complex Network Theory is applied to characterize the behavior of WDNs from a topological point of view, reviewing some basic metrics, exploring their fundamental properties and the relationship between them. The crucial aim is to understand and describe the topology of WDNs and their structural organization to provide a novel tool of analysis which could help to find new solutions to several arduous problems of WDNs. The aim is to understand the role of the topological structure in the WDNs functioning. The methodology is applied to 21 existing networks and 13 literature networks. The comparison highlights some topological peculiarities and the possibility to define a set of best design parameters for ex-novo WDNs that could also be used to build hypothetical benchmark networks retaining the typical structure of real WDNs. Two well-known types of network ((a) square grid; and (b) random graph) are used for comparison, aiming at defining a possible mathematical model for WDNs. Finally, the interplay between topology and some performance requirements of WDNs is discussed. [ABSTRACT FROM AUTHOR]

Near real-time monitoring and control of critical infrastructure is essential for the operation and management of cities in a world that is, today, more complex and interconnected than ever. Such an infrastructure can be represented as complex networks an some of their related indices and statistics, many of them based on the shortest paths, play a pivotal role in the decision making for public services such as internet, energy or water. Particularly, the literature has shown that shortest paths are key for resilience and criticality assessment in a water distribution systems (WDS). This paper proposes a procedure to speed-up the computation of shortest paths in a WDS, as it can straightforwardly benefit any critical infrastructure. The proposal is based on a reduced dimension of a complex network representing any critical infrastructure. Despite the consequent decrease in the number of all possible paths in the network, the main advantage and novelty of this proposal is to continue finding the exact solution for the shortest paths. Experimental results show that the procedure brings a computational-time reduction consistently over 50% and up to 90% in some cases. In addition, the paper reveals how the use of shortest paths benefits WDS operation and management, as well as playing a key role in near real-time contamination detection and leakage control. • Novel dimensionality-reduction process to compute shortest paths in networked systems. • Innovative use of shortest paths supporting near real-time decision making of water utilities. • Relationship between shortest paths and contamination spread on water distribution systems. • Shortest-paths based approach for dynamically management of district areas of water supply. [ABSTRACT FROM AUTHOR]

The optimal and sustainable management of water distribution systems still represent an arduous task. In many instances, especially in aging water net-works, pressure management is imperative for reducing breakages and leakages. Therefore, optimal District Metered Areas represent an effective solution to decreasing the overall energy input without performance compromise. Within this context, this paper proposes a novel adaptive management framework for water distribution systems by reconfiguring the original network layout into (dynamic) district metered areas. It utilises a multiscale clustering algorithm to schedule district aggregation/desegregation, whilst delivering energy and supply management goals. The resulting framework was tested in a water utility network for the simultaneously production of energy during the day (by means of the installation of micro-hydropower systems) and for the reduction of water leakage during the night. From computational viewpoint, this was found to significantly reduce the time and complexity during the clustering and the dividing phase. In addition, in this case, a recovered energy potential of 19 MWh per year and leakage reduction of up to 16% was found. The addition of pump-as-turbines was also found to reduce investment and maintenance costs, giving improved reliability to the monitoring stations. The financial analyses to define the optimal period in which to invest also showed the economic feasibility of the proposed solution, which assures, in the analysed case study, a positive annual net income in just five years. This study demonstrates that the combined optimisation, energy recovery and creation of optimized multiple-task district stations lead to an efficient, resilient, sustainable, and low-cost management strategy for water distribution networks. • Novel automatic approach for dynamic/adaptive water network partitioning. • Optimisation of multiple-task monitoring stations for a sustainable management of water systems. • Decision framework for saving energy, water, cost, and reliability in water systems. • Recovering local kinetic energy augment in partitioned water distribution systems. • Districts boundary pipes are desirable locations for micro hydropower systems. [ABSTRACT FROM AUTHOR]