Vulnerability Assessment of Water Distribution Networks Under Abnormal Operating Conditions and Nonseismic Loads – The Case of Intermittent Water Supply (IWS)

Author(s):  
Symeon E. Christodoulou ◽  
Michalis Fragiadakis ◽  
Agathoklis Agathokleous ◽  
Savvas Xanthos
2017 ◽  
Vol 19 (6) ◽  
pp. 838-852 ◽  
Author(s):  
Agathoklis Agathokleous ◽  
Chrystalleni Christodoulou ◽  
Symeon E. Christodoulou

Abstract Water authorities in countries facing water shortage problems are implementing intermittent water supply (IWS) policies, as a measure to conserve and control their national water resources. Implementation of such measures affects the behaviour of the water pipe systems during the operation stage. The research work presented herein presents a model simulating the behaviour of urban water distribution networks (WDNs) under normal operating conditions, as well as during a period of IWS operations. The modelling and analysis, based on an eight-year dataset (2003–2010) from a local Water Board, takes into account information related to breakage incidents within the WDN as well as external factors to perform vulnerability assessment of the pipe network. The results of the performed survival and cluster analysis show that during the implementation period of IWS operations, and right after that period, there is a significant increase in the deterioration rate of the affected network. Further, there is a change in the comparative importance of the factors affecting the network condition and their contribution to the WDN vulnerability.


2012 ◽  
Vol 12 (4) ◽  
pp. 523-530 ◽  
Author(s):  
S. Christodoulou ◽  
A. Agathokleous

Faced with extended periods of drought and short supply of water, arid-weather countries have turned to intermittent water supply (IWS) as a means to reduce water consumption and to prolong their national water reserves. Unfortunately, such drastic measures usually fail to consider the effects of intermittent supply on the condition of piping networks and the resulting water losses, inefficiencies and overall maintenance cost on these networks. Presented herein is research work on the effects of IWS on the vulnerability of urban water distribution networks (UWDN) based on a 3-year dataset from major urban centres in Cyprus. The dataset includes information on breakage incidents, operating network parameters, external factors and vulnerability assessment and by use of data-mining and survival analysis techniques evaluates the effects of such intermittent supply strategies on the vulnerability of the water pipes and on the sustainability of the strategy.


2015 ◽  
Vol 64 (6) ◽  
pp. 660-669 ◽  
Author(s):  
Kalyan R. Piratla ◽  
Samuel T. Ariaratnam

Water distribution networks (WDNs) play a crucial role in the well-being of human populations and economic prosperity. It is essential that they cope with abnormal operating conditions and recover functionality quickly. Traditionally, WDNs are designed using cost and reliability objectives, but there is a lack of consensus on the definition and quantification of reliability which typically is a computationally intense process. Subsequently, various reliability-like metrics, called resilience indices, have been developed and demonstrated in the design of WDNs. Few studies exist that thoroughly evaluate the performance of the previously developed resilience metrics. This paper investigates three resilience metrics by evaluating their performance on three benchmark WDNs for several simulated mechanical failure states. The metrics studied are: (a) resilience index, (b) network resilience index (NRI), and (c) modified resilience index (MRI). The metric MRI performed better overall but NRI produced cheaper designs that performed better in the case of WDN-I. It is recommended that a better metric that incorporates different dimensions of resilience, such as robustness and redundancy, should be developed in the future.


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