Graph Neural Network for Integrated Water Network Partitioning and Dynamic District Metered Areas

Water distribution systems (WDSs) are used to transmit and distribute water resources in cities. Water distribution networks (WDNs) are partitioned into district metered areas (DMAs) by water network partitioning (WNP), which can be used for leak control, pollution monitoring, and pressure optimization in WDS management. In order to overcome the limitations of optimal search range and the decrease of recovery ability caused by two-step WNP and fixed DMAs in previous studies, this study developed a new method combining a graph neural network to realize integrated WNP and dynamic DMAs to optimize WDS management and respond to emergencies. The proposed method was tested in a practical case study; the results showed that good hydraulic performance of the WDN was maintained and that dynamic DMAs demonstrated excellent stability in emergency situations, which proves the effectiveness of the method in WNP.

Water Network Partitioning into District Metered Areas: A State-Of-The-Art Review

A water distribution network (WDN) is an indispensable element of civil infrastructure that provides fresh water for domestic use, industrial development, and fire-fighting. However, in a large and complex network, operation and management (O&M) can be challenging. As a technical initiative to improve O&M efficiency, the paradigm of “divide and conquer” can divide an original WDN into multiple subnetworks. Each subnetwork is controlled by boundary pipes installed with gate valves or flow meters that control the water volume entering and leaving what are known as district metered areas (DMAs). Many approaches to creating DMAs are formulated as two-phase procedures, clustering and sectorizing, and are called water network partitioning (WNP) in general. To assess the benefits and drawbacks of DMAs in a WDN, we provide a comprehensive review of various state-of-the-art approaches, which can be broadly classified as: (1) Clustering algorithms, which focus on defining the optimal configuration of DMAs; and (2) sectorization procedures, which physically decompose the network by selecting pipes for installing flow meters or gate valves. We also provide an overview of emerging problems that need to be studied.

An Improved Genetic Algorithm for Optimal Layout of Flow Meters and Valves in Water Network Partitioning

The paradigm of “divide and conquer” has been well used in Water Distribution Systems (WDSs) zoning planning in recent years. Indeed, Water Network Partitioning (WNP) has played an irreplaceable role in leakage control and pressure management; meanwhile it also has certain drawbacks, such as reduction of the supply reliability of the pipe network system and increased terminal dead water, as a result of the closure of the pipe section. In this paper, an improvement is made to the method proposed by Di Nardo et al. (2013) for optimal location of flow meters and valves. Three improvements to the genetic algorithm are proposed in this work for better and faster optimization in the dividing phase of WNP: preliminary hydraulic analysis which reduces the number of decision variables; modifications to the crossover mechanism to protect the superior individuals in the later stage; and boundary pipe grouping and mutation based on the pipe importance. The objective function considers the master–subordinate relationship when minimizing the number of flow meters and the difference of hydraulic state compared to original WDS. Another objective function of minimizing the deterioration of water quality compared to original WDS is also evaluated. The proposed method is applied for the WNP in a real WDS. Results show that it plays an effective role in the optimization of layout of the flow meters and valves in WNP.

Optimal Sensor Placement in a Partitioned Water Distribution Network for the Water Protection from Contamination

Water network protection from accidental and intentional contamination is one of the most critical issues for preserving the citizen health. Recently, some techniques have been proposed in the literature to define the optimal sensor placement. On the other hand, through the definition of permanent DMAs (District Meter Areas), water network partitioning allows significant reduction in the number of exposed users through the full isolation of DMA. In this paper, the optimal sensor placement is coupled with water network partitioning in order to define the best location of isolation valves and control stations, to be closed and installed respectively. The proposed procedure is based on different procedures, and it was tested on a real water network, showing that it is possible both to mitigate the impact of a water contamination and simplify the sensor placement through the water network partitioning.

Dual-use value of network partitioning for water system management and protection from malicious contamination

This paper considers the introduction of a contaminant into a water supply system using a backflow attack. The recent development of techniques for water network sectorization, aimed at improving the management of water systems, is also an efficient way to protect networks from intentional contamination and to reduce the risk of the dangerous effects of network contamination. Users can be significantly protected by isolated district meter areas (i-DMAs) in the water network and the closing of the gate valves by a remote control system to implement such i-DMAs in cases of malicious attacks. This study investigates the effects of different approaches for water network partitioning and sectorization to protect networks using a technique for designing i-DMAs that is compatible with hydraulic performance and that is based on graph theory and heuristic optimization. For this analysis, the introduction of cyanide through a backflow attack was assumed. The methodology was tested on a large water network in Mexico and displayed good protection from a malicious attack.

Performance indices for water network partitioning and sectorization

Water network partitioning in district metering areas, or sectorization, is an important process for improving water network management. It can help water utilities to implement active leakage control, conduct pressure management, and prevent network contamination. It is generally achieved by closing some network pipes, thus reducing pipe redundancy and affecting system performance. No systematic set of performance indices has been defined to evaluate a sectorization design and thus allow for a comparison of different possible sectorizations on a formal basis. In this paper, several performance indices for water network partitioning are proposed and tested using two real water supply systems: Parete in Italy and Matamoros in Mexico. Both systems' sectorizations were previously designed by a novel effective automatic technique recently developed by the authors. For both the original and sectorized networks, the proposed performance indices considered energy dissipated in the network, network resilience, pressure variation, fire-fighting capacity, water age, and mechanical redundancy. Network resilience appears to be the most representative index for the entire network, whereas pressure variation indices are more appropriate for describing individual districts. Except for fire-fighting capacity in one network, system performance did not appear to be affected significantly after sectorization.