• Journal of Korea Water Resources Association
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• v.52 no.10
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• pp.719-728
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• 2019

Valve in water distribution network (WDN), that controls the flow in pipes, is used to isolate a segment (a part of WDN) under abnormal water supply conditions (e.g., pipe breakage, water quality failure event). The segment isolation degrades pressure and water serviceability in neighboring area during the water service outage of the segment. Recent hydraulic and water quality failure events reported encouraging WDN valve installation based on various abnormal water supply scenarios. This study introduces a scenario-based optimal valve installation approach to optimize the number of valves, the amount of undelivered water, and a shortest water supply path indicator (i.e., Hydraulic Geodesic Index). The proposed approach is demonstrated in the valve installation of Pescara network, and the optimal valve sets are obtained under multiple scenarios and compared to the existing valve set. Pressure-driven analysis (PDA) scheme is used for a network hydraulic simulation. The optimal valve set derived from the proposed method has 19 fewer valves than the existing valve set in the network and the amount of undelivered water was also lower for the optimal valve set. Reducing the reservoir head requires a greater number of valves to achieve the similar functionality of the WDN with the optimal valve set of the original reservoir head. This study also compared the results of demand-driven analysis (DDA) and the PDA and confirmed that the latter is required for optimal valve installation.

• Journal of Korea Water Resources Association
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• v.55 no.spc1
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• pp.1211-1222
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• 2022

Abnormal condition inevitably occurs during operation of water distribution system (WDS) and requires the isolation of certain areas using isolation valves. In general, the determination of the optimal location of isolation valves considered minimization of hydraulic failures as isolation of certain areas causes a change in hydraulic states (e.g., flow direction, velocity, pressure, etc.). Water quality failure can also be induced by changes in hydraulics, which have not been considered for isolation valve system design. Therefore, this study proposes a new isolation valve system design methodology to prevent unexpected water quality failure events. The new methodology considers flow direction change ratio (FDCR), which accounts for flow direction changes after isolation of the area, as a constraint while reliability is used as the objective function. The optimal design model has been applied to a synthetic grid network and the results are compared with the traditional design approach. Results show that considering FDCR can eliminate flow direction changes while average pressure and coefficient of variation of pressure, velocity, and hydraulic geodesic index (HGI) outperform compared to the traditional design approach. The proposed methodology is expected to be a useful approach to minimizing unexpected consequences by traditional design approaches.