Maintenance Of Water Distribution Systems Research Articles

Extremely Sensitive Anomaly Detection in Pipe Networks Using a Higher-Order Paired-Impulse Response Function with a Correlator

Detection of anomalies in pipe networks (leaks, blockages, and wall deterioration) is critical for targeted pipe section replacement and maintenance in water distribution systems. A hydraulic signal-processing approach, termed the paired-impulse response function (paired-IRF), has been previously proposed for anomaly detection by transforming the persistent principal wave reflections by anomalies into distinctive paired spikes. In this paper, a new higher-order paired-IRF has been derived, which considers both principal and higher-order wave reflections by the anomalies. A correlator has then been designed (and incorporated into the higher-order paired-IRF) to highlight anomaly-induced spikes and suppress noise. A looped pipe network with realistic background noise was assembled in the laboratory to examine the efficacy of the new methods. According to the experimental results, it is observed that (1) the higher-order paired-IRF is an extremely sensitive detection technique and clearly identifies anomalies inducing wave reflections as small as 0.5% of the injected wave magnitude; (2) its sensitivity is sufficiently accurate when using micropressure waves as small as 20 mm in magnitude and contaminated by 2-m background pressure fluctuations; and (3) the proposed advanced correlator highlights the anomaly-induced spikes in the paired-IRF trace in a noisy environment.

The optimisation of a water distribution system using Bentley WaterGEMS software

The proper maintenance of water distribution systems (WDSs) requires from operators multiple actions in order to ensure optimal functioning. Usually, all requirements should be adjusted simultaneously. Therefore, the decision-making process is often supported by multi-criteria optimisation methods. Significant improvements of exploitation conditions of WDSs functioning can be achieved by connecting small water supply networks into group systems. Among many potential tools supporting advanced maintenance and management of WDSs, significant improvements have tools that can find the optimal solution by the implemented mechanism of metaheuristic methods, such as the genetic algorithm. In this paper, an exemplary WDS functioning optimisation is presented, in relevance to a group water supply system. The action range of optimised parameters included: maximisation of water flow velocity, regulation of pressure head, minimisation of water retention time in a network (water age) and minimisation of pump energy consumption. All simulations were performed in Bentley WaterGEMS software.

Subsystem-based pressure dependent demand analysis in water distribution systems using effective supply

In this study, Subsystem-Based Pressure Dependent Demand (SPDD) analysis is implemented using the concept of effective supply to eliminate the uncertainties caused by the Head-Outflow Relationship (HOR) in Pressure Dependant Demand (PDD) analysis. This study optimizes the nodal water demands to satisfy the nodal pressure requirement under the abnormal condition defined as the part of the water distribution systems that is closed due to maintenance, rehabilitation, or accidents. The total water supply is optimized and defined as the effective supply, which is the maximum water supply while maintaining the nodal pressure requirements (25 psi) to guarantee the customer’s convenience. A meta-heuristic algorithm, the Harmony Search (HS) algorithm, is applied to optimize the system. To decrease the effect of the HOR uncertainties, an optimization method is proposed in this study using the EPANET model that is widely used for the hydraulic simulation. To evaluate the applicability of the suggested model, Supply Index (SI), Pressure Index (PI), Effective Supply Index (ESI), and Subsystem Importance Index (SII) are also defined and calculated from a real-sized network. This paper firstly tried to perform pressure dependent demand analysis for subsystem without the HOR equation that has been an important issue in water distribution system analysis. The developing method could be a good alternative for the design and maintenance of water distribution systems.

Optimization of pressure gauge locations for water distribution systems using entropy theory

It is essential to select the optimal pressure gauge location for effective management and maintenance of water distribution systems. This study proposes an objective and quantified standard for selecting the optimal pressure gauge location by defining the pressure change at other nodes as a result of demand change at a specific node using entropy theory. Two cases are considered in terms of demand change: that in which demand at all nodes shows peak load by using a peak factor and that comprising the demand change of the normal distribution whose average is the base demand. The actual pressure change pattern is determined by using the emitter function of EPANET to reflect the pressure that changes practically at each node. The optimal pressure gauge location is determined by prioritizing the node that processes the largest amount of information it gives to (giving entropy) and receives from (receiving entropy) the whole system according to the entropy standard. The suggested model is applied to one virtual and one real pipe network, and the optimal pressure gauge location combination is calculated by implementing the sensitivity analysis based on the study results. These analysis results support the following two conclusions. Firstly, the installation priority of the pressure gauge in water distribution networks can be determined with a more objective standard through the entropy theory. Secondly, the model can be used as an efficient decision-making guide for gauge installation in water distribution systems.

Quo vadis water distribution model calibration?

Hydraulic water distribution system (WDS) simulation models are widely used by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems. Similarly, water quality models that work in concert with hydraulic models are now commonly used to simulate the dispersion of and changes in water quality in a water distribution network. As with all mathematical models, WDS model parameters (hydraulic and water quality) require calibration before useful results may be obtained. Nowadays, automated calibration procedures are widely available for hydraulic models, but less so for water quality models. Even when they are available as commercial software, the use of these advanced calibration tools in engineering practice has been limited. This paper provides a review of model calibration approaches and considers future challenges and directions.

Identifying Pipes and Valves of High Importance for Efficient Operation and Maintenance of Water Distribution Systems

Failure of a pipe or valve in a water distribution system causes service disruption and other inconveniences to the customers at or downstream of the failure location. To minimize the impact of such a pipe or valve failure, it is crucial to identify those pipes or valves whose failure will have the most severe consequences in degrading the performance of the system relative to that of other pipes or valves. In this paper, we develop two failure analysis methodologies, Pipe-by-Pipe and Valve-by-Valve, to prioritize the importance of pipes and valves in a water distribution system. The relative importance of individual pipes and valves is evaluated according to the number of customers who are forced out of service as a consequence of a pipe or valve failure. The methodologies are based on a segment-finding algorithm which defines a series of isolated pipes in the case of pipe or valve failure. A procedure based on the Breadth First Search is also developed to find sections of pipes that are unintentionally isolated in the isolation procedure for failed pipes. The number of unintentionally isolated customers is included in the Pipe-by-Pipe and Valve-by-Valve analyses in order to incorporate this negative effect of unintended isolation of pipes. The methodologies are applied to a case study of a water distribution system for which the most important pipe and valve are identified. The results are analyzed to form a guideline for improving the system reliability. The proposed methodologies were found to be a valuable tool for ensuring efficient operation and developing appropriate maintenance strategies, and thereby for improving the reliability of many water distribution systems.