Leakage Effects on the Variables of Water Distribution System

1Nasereddin I. Sherksi, Sahrim Lias, Labeeb M., Ramli Adnan, 2Mohd Nasir Taib Faculty of Electrical Engineering, University Teknologi MARA (UiTM)

40450 Shah Alam, Selangor Darul Ehsan, Malaysia 1nasersharksi@yahoo.com

2dr.nasir@ieee.org

Abstract—One of the key factors to understand and find solutions for any challenge related to Water Distribution System(WDS) is begin from understanding the behaviors of its variables under specific circumstances, in this paper various experiments are conducted to figure out and analyze the effects of leakage on the variables of WDS, i.e. pressure, pipe volume ,velocity , water demands and flow. The results of these experiments showed that the most affected variables when the WDS suffer from leakage is the pressure, followed by flow , while the least affected variable is velocity .

Index Terms— Leakage, WDS, water distribution system.

I. INTRODUCTION The pressure and stress on the water resources are mainly

due to: increasing in the water demand and water supply reduction. Yet one of the solutions to mitigate the effects of the water stress is the public water leakage reduction in the water system. Leakage reduction is an essential part in the management of water demand [1]. From this point, understanding the key components in any Water Distribution System (WDS) will enhance the ability of providing robust solutions to overcome WDS related challenges. Many researches have been carried out for the purpose of improving our understanding for both: water losses control and leakage [2-6].However, the endeavor of reducing water losses to reasonable levels still elusive [7]. It is now recognized that the complexities involved in this problem are much greater than initially thought. Although much progress has been made in understanding the various factors that affect water losses, much still remains to be done[7] .Thus a more detailed work needed to highlight the significance of each parameter in the process of leak dedication in WDS ,also in order to shed some light on the key components of any WDS system, we discussed in this work the mutual effects of pressure , flow, velocity, system’s pipe volume and water demands on the WDS with no leak , minimum leak , and 25% of leak (which is the case in most real WDS systems)[9]. Also we chose to use real WDS system with real reading data to reflect and obtain reliable results.

II. PROPOSED METHOD The proposed method to study the mutual effects of the

parameters of flow ,pressure ,pipe’s volume and velocity on the leakage behaviour in the WDS is done by comparing the mutual effects of each peer of the correlated parameters with the leakage value in the WDS .Each peer are simulated by using EPANET and MATLAB simulators supplied with actually data with the assumption of WDS are operated for 24 hours with different water losses (leakage ) to understand the behaviour of WDS and its parameters with such differences in leakage values .Next the reading are collected and compared as shown in the section of result and discussion.

III. PARAMETERS OF SIMULATION AND PATTERNS The model is simulated depending on realistic Water

Disruption System existed in Benghazi –Libya. The model is shown in Figure 1.Although EPANET is a software primarily designed for modeling network supply and water quality issues, the emitter property in EPANET which designed to model fire hydrants/sprinklers can be also adapted to model leaks. The definition of the emitter is based on the classical Torricelli equation for flow through an orifice .The calculation of the Emitter Coefficient are obtained from equation (1) [9] ,the used parameter are shown in Table 1, where flow rate percentage represents the percentage of water losses in the system caused by leak, the 25% are chosen due to the majority of the real cases of leak in WDS are no more than 25%, while the leak flow rate represents the real value of the leak flow rate losses.The Demand differences is the difference between base demand and actual demand .The reading are taken from 24 hours monitoring time of the WDS.

2013 IEEE Conference on Systems, Process & Control (ICSPC2013), 13 - 15 December 2013, Kuala Lumpur, Malaysia

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Fig. 1.WDS of Benghazi (real network) with single leak introduced

TABLE I. LEAKAGE VALUES USED IN THE TESTS

No leak

Min. leak

Quarter leak

Leakage flow rate percentage

0% 0.25 % 25%

Leakage flow rate 0 0.677 69.074 To calculate the Discharge Coefficient in which to find the Leakage rate: Coefficient calculation(C or EC)

q = Cpα (1) C = q /pα

where q = flow rate C = discharge coefficient and α = pressure exponent. For nozzles and sprinkler heads α equals 0.5.

V. RESULTS AND DISCUSSION

A. Pressure versus Demand Pressure considered as one of the major factors effecting

leakage in water distribution system. The first experiment conducted is to find the effects of Pressure versus Water Demand on the DWS for the three possible cases that can WDS experienced, i.e. no leak, with minimum leak and 25% leak. Looking at Figure 2 ,the difference can be observed when the value of the leakage is 25% ,where both pressure and actual demand are clearly affected from the single 25% introduced leakage ,thus , we can conclude that pressure is one of the important factors that can be affected by leakage.

Fig.2 -a. Pressure vs. Demand difference for no leak condition

Fig. 2-b. Pressure vs. Demand difference for minimum leak condition

Fig.2-c. Pressure vs. Demand difference for 25% leak condition.

Single leakage

2013 IEEE Conference on Systems, Process & Control (ICSPC2013), 13 - 15 December 2013, Kuala Lumpur, Malaysia

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B. Flow versus Pipe Volume The relation between flow rate and pipe diameter is

directly proportional to the area of the cross-section, thus, in the case of pipe’s diameter increased, the flow rate increased as well in exponential manner. This relation is described by equation (3) [11].

2

2⎟⎠⎞

⎜⎝⎛= dA π (2)

where A is the cross-sectional area and d is the diameter. By adding the length L of the pipe to Eq. (2), we get the pipe

volume, 32

2

mdLV ⎟⎠

⎞⎜⎝

⎛= π

From Figure 3 we can observe that there are differences in the flow but not clearly in the volume among the three figures. Moreover, only the Flow is very significantly affected from the single 25% leakage introduced.

Fig. 3(a). Flow vs. Pipe Volume for no leak condition

Fig. 3(b). Flow vs. Pipe Volume for minimum leak condition

Fig. 3(c). Flow vs. Pipe Volume for 25% leak condition

C. Flow Versus Velocity The two terms of flow and velocity sometimes might be confusing and mistakenly interchanged. Flow in WDS is the water’s volume that is moving per unit of time while Velocity is the distance that water moves with respect to time [12]. Equation (3) shows the relation between the Flow and Velocity.

VAF = (3)

where F represents the flow while V is the mean velocity, and A is the cross-sectional area of the pipe [10] .From Figure 4, there are differences among the 3 figures for all the 24 monitoring time for the Velocity and Flow. Thus we can conclude that both Flow and Velocity are slightly affected from the single 25% and maximum leakage introduced.

Fig. 3(a). Flow vs. Velocity for no leak condition

2013 IEEE Conference on Systems, Process & Control (ICSPC2013), 13 - 15 December 2013, Kuala Lumpur, Malaysia

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Fig. 3(b). Flow vs. Velocity for minimum leak condition

Fig. 3(c). Flow vs. Velocity for 25% leak condition

VI. CONCLUSION AND FUTURE WORK Assigning DWS’s parameters in peers, can ease the

challenge of understanding the behaviors of these parameters under the circumstances of DWS leakage .The parameters shown uneven behaviors with the variation of leakage values .Regarding to the experiments results ,it can be concluded that the most affected variables when the WDS suffer from leakage is the Pressure, followed by Flow , while the least affected variable is the Velocity .The results can be helpful to the efforts of WDS leak detection and water loose mitigation. For the future work, we are going to analyze the behaviours of the four types of consumers of the WDS (Domestic, Industrial Commercial, Official,) under the cases of no leak , minimum leak , midnight flow ,and 25% leak to observe the behaviour of the network and analysis the effect on each type of the consumers .

ACKNOWLEDGEMENT The authors would like to thanks and acknowledge the

financial support from the Faculty of Electrical Engineering, Universiti Teknologi MARA, Shah Alam.

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[Online].Available:http://growingblue.com/casestudies/leakages-in-water-distribution-systems/

[2] T.Walski, et al “Modelling Leakage reduction through pressurecontrol” journal AWWA- April 2006.

[3] O. Giustolisi1, et al “Pressure-Driven Demand and LeakageSimulation for Water Distribution Networks” Journal ofHydraulic Engineering, Vol. 134, No. 5, May 1, 2008.

[4] N. Zhang, et al “Research and Application on Leakage Model ofWater Distribution System” International Symposium onWater Resource and Environmental Protection (ISWREP). 2011.

[5] A. Di Nardo, et al “Demand Pattern and Leakage Identification In WDN” 33rd IAHR Congress ,International Association of Hydraulic Engineering & Research ISBN: 978-94-90365-01-1. 2009.

[6] J.E. van Zyl “The Effect Of Pressure On Leaks In WDS” Water Institute of Southern Africa (WISA) Biennial Conference 2 6 May 2004.

[7] C. R. I. Clayton and J. E. van Zyl, “The effect of pressure on leakage in water distribution systems,” Proceedings of the ICE -Water Management, vol. 160, no. 2, pp. 109–114, Jan. 2007.

[8] J. E. Van Zyl and L. F. R. Reis, “EXTENSION OF EPANETFOR PRESSURE DRIVEN DEMAND MODELING IN WATER DISTRIBUTION SYSTEM,” pp. 2–7.

[9] J. Mashford, D. De Silva, D. Marney, and S. Burn, “An Approach to Leak Detection in Pipe Networks Using Analysis of

Monitored Pressure Values by Support Vector Machine,” 2009 Third International Conference on Network and System Security, pp. 534–539, 2009.

[10] C. R. I. Clayton and J. E. van Zyl, “The effect of pressure on leakage in water distribution systems,” Proceedings of the ICE - Water Management, vol. 160, no. 2, pp. 109–114, Jan. 2007.

[11] Brad Painting, " Flow Vs. Pipe Diameter" eHow, [Online].Available:http://www.ehow.com/facts_6828698 _flow-vs_-pipediameter.html

[12] Richard E. Klabunde," Velocity versus Flow" , eHow,[Online].Available:"http://www.cvphysiology.com/Hemodynamics/H013.htm.

2013 IEEE Conference on Systems, Process & Control (ICSPC2013), 13 - 15 December 2013, Kuala Lumpur, Malaysia

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