1. Integrated Reliability Assessment of Water
Distribution Networks
Presented by:
Azhar Uddin Mohammed
Supervisors:
Dr. Tarek Zayed, Dr. Osama Moselhi
January 26, 2016

2. 2
Introduction
Literature Review
Research Methodology
Data Collection
Model Implementation
Conclusion
Outline

3. Introduction Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
3
Water Distribution Networks
The total water use per capita (FAO, 2013)
Canada - 1,150 gal/inhab/day
USA - 1,146 gal/inhab/day
Population growth (SOTWI, 2013)
Canada - 4.6%
USA - 3.9%

4. Introduction Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
4
Water Distribution Networks
Drinking water networks in the United States
are graded “D – Poor Condition” (ASCE, 2013)
Restoring one million miles of existing water
networks costs
―$1 trillion over next 25 years (AWWA, 2012)
―$384 billion by 2030 ignoring population growth
(EPA, 2013)

5. Introduction Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
5
Water Distribution Networks
According to CIR (2012),
Canadian drinking water infrastructure is
graded “Good : adequate for now”
15.4% of water distribution systems are graded
“fair” to “very poor”
CAD 25.9 billion replacement cost estimated

6. Introduction Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
6
Water Distribution Networks
According to ASCE (2013), water and wastewater
infrastructure in the United States to reach B
grade by 2020
Required investment - $126 billion
Estimated funding - $42 billion
Investment gap - $84 billion

7. Introduction Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
7
Problem Statement
Assessment of individual pipes ignoring other components
Assessment of network ignoring the importance of crucial
water main connections
Mechanical and hydraulic failures are studied independently
Hydraulic performance evaluated ignoring the effect of
pressure on demands

8. Introduction Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
8
Objectives
 Develop a comprehensive reliability assessment model that
can identify the crucial water mains and prioritize their renewal
 Identify and study the factors impacting mechanical and hydraulic
reliability at various hierarchical levels
 Develop mechanical and hydraulic models to assess network reliability
 Develop an integrated reliability assessment model considering
mechanical and hydraulic aspects
 Semi-Automate the developed model using coded scripts

9. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
9
Literature Review
Water Distribution
Network
Failure Rate of
Components
Reliability of Water
Distribution Networks
Network Reliability
Analysis
Probability of Failure
Segment
WDN
Components
Types of
Failure
Failure Rate
Curve
Normal
Exponential
Weibull
Definition of
Reliability
Types of
Reliability
Reliability
Assessment
Methods
Series Parallel
Systems
Minimum Cut
Set Analysis
Hydraulic
Network Analysis

10. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
10
Reliability of Water Distribution Networks
Reliability
Mechanical
Reliability
Pipes Valves Hydrants Pumps
Hydraulic
Reliability
Pressure
Head
Demand
Variation
Water
Quality
Reliability

11. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
11
Reliability of Water Distribution Networks
• Associated with probability of a network to remain physically
connected
Connectivity/ Topological
• Conveyance of water at required quantity and pressure
Hydraulic
• Uncertainty that quantifies the amount of information in a finite
probability distribution
Entropy as a reliability surrogate

12. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
12
Network Reliability Analysis
Series Parallel Systems
Minimum Cut Set Analysis
Hydraulic Network Analysis
5
2
43
1
6
a
b c
de
f
g h
i
• First Order Cut Sets{i}
• Second Order Cut Sets{f,g}
• Third Order Cut Sets
{a,c,h},
{a,b,g},
{b,c,d}, {d,h,f}
Minimum set of network segments which, when failed,
causes failure of the network; but if just one segment of
the set has not failed, no failure of network occurs

13. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
13
Network Reliability Analysis
Hydraulic Network Analysis
Demand Driven Analysis (DDA)
• Surpass demand driven analysis, particularly for networks under abnormal operating conditions
• Considers the pressure dependency of nodal outflows, and in consequence, the results are more
realistic
• Objective of PDA is to establish the actual supply quantity and pressure at each node in a WDN
• Assumes that consumer demands are always satisfied regardless of the pressures
• Acceptable results when WDNs are subject to normal operating conditions
• When the pressure drops below the required level, no information on how much water would be
delivered by the system
• Results indicate the system is still supplying the full demand at lower, and sometimes, negative
pressures
Pressure Driven Analysis (PDA)

14. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
14
Network Reliability Analysis
Hydraulic Network Analysis
Category Method
First Generation Hardy Cross Method
Second Generation Linear Method, Newton Raphson Method
Third Generation Gradient Algorithm
Fourth Generation Enhanced Global Gradient Algorithm
Fifth Generation
First Order Reliability, Fuzzy Sets and
Systems
WaterCAD by Bentley
Tsakiris and Spiliotis (2014)

15. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
15
Network Reliability Analysis
• Gkountis (2014); Semaan (2011); El Chanati (2014);
Salman (2011); Ghodoosi et al. (2013)
Series Parallel Systems
• Zhou et al. (2012); Alhomidi and Reed (2013);
Yannopoulos; Spiliotis (2013); Shinstine et al. (2002)
Minimum Cut Set Analysis
• Tsakiris & Spiliotis (2014); Giustolisi and Laucelli (2011);
Pathirana (2011); Ghajarnia et al. (2009)
Hydraulic Network Analysis

16. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
16
 Water utilities usually ignore and do not record the causes of failure
 Reliability techniques were either applied to small scale networks or assessed
mechanical and hydraulic reliability independently
 Hydraulic models were found to be demand driven
 Pressure driven models were analyzed manually rather than analyzing in a
simulating environment
Limitations of Previous Studies

17. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
17
Research Methodology
Failure Rate
Pipes Accessories
Component
Reliability
Segment
Reliability
Network
Minimum Cut
Set Analysis for
allNodes
Record Minimum
Cut Sets
Integrated Reliability
Assessment of WDN
Literature
Review
Failure Probability
Models
Reliability Assessment
Methods
Reliability
Classification
Failure Causes and
Consequences
Data Collection
London Doha
LiteratureReview Best Practices
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Bentley WaterCAD Library
Required Demand
Service
Pressure Head
Available
Pressure Head

18. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
18
Failure Rate
Pipes Accessories
Component
Reliability
Segment
Reliability
Network
Mechanical
Reliability
Minimum Cut
Set Analysis for
allNodes
Record Minimum
Cut Sets
Failure Rate
Pipe Accessories
λPipe = 6 × 10−6
X2
+ 0.0004X + 0.0026
λComponent
=
Nf
Length of Segment
X is Age of pipe
Nf is Number of
failures
Component Reliability
Rc = e−λt
Rc is Component
Reliability
Segment Reliability
RSeg =
i=1
n
Rcwi
Wi is Relative Weight
of Components
Rseg is Segment
Reliability
Relative Weight wi
=
Weight of Components
Sum of Weights of all Components

19. Minimum
Cut Set
Analysis
Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
19
Failure Rate
Pipes Accessories
Component
Reliability
Segment
Reliability
Network
Mechanical
Reliability
Minimum Cut
Set Analysis for
allNodes
Record Minimum
Cut Sets
Path
Matrix
• Find all possible paths from source node to destination node
• Create path matrix
First Order
Cut Sets
• From the path matrix, check if any column is non zero
• Any non zero column is a first order cut set
Second
Order Cut
Sets
• Combine any two columns representing segments in a path matrix
and check if their addition creates a non zero column
• Resultant non zero is a second order cut set

20. Minimum
Cut Set
Analysis
Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
20
Failure Rate
Pipes Accessories
Component
Reliability
Segment
Reliability
Network
Mechanical
Reliability
Minimum Cut
Set Analysis for
allNodes
Record Minimum
Cut Sets
S D
A
CC
BB
P =
A B C
1 1 0
1 0 1
• {A-B}
• {A-C}
Possible
Paths
Path
Matrix First Order Cut Set

21. Minimum
Cut Set
Analysis
Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
21
Failure Rate
Pipes Accessories
Component
Reliability
Segment
Reliability
Network
Mechanical
Reliability
Minimum Cut
Set Analysis for
allNodes
Record Minimum
Cut Sets
S D
A
CC
BB
P =
A B C
1 1 0
1 0 1
• {A-B}
• {A-C}
Possible
Paths
Path
Matrix First Order Cut SetP =
A+B B+C C+A
1 1 1
1 1 1
Modified
Path
Matrix
Second Order Cut Set
MS Excel 2013
Mathematica 10.2
MATLAB R2013b

22. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
22
Failure Rate
Pipes Accessories
Component
Reliability
Segment
Reliability
Network
Mechanical
Reliability
Minimum Cut
Set Analysis for
allNodes
Record Minimum
Cut Sets
Mechanical Reliability based on Minimum Cut Sets
𝐐 𝐌𝐂𝐢 = 𝐣=𝟏
𝐧
𝐐𝐣 𝐑 𝐍 = 𝟏 − 𝐢=𝟏
𝐌
𝐐(𝐌𝐂𝐢)
Identification of Minimum Cut Sets
Path Matrix First Order Cut Sets Second Order Cut Sets
Probability of Failure of Segments
𝐐 = 𝟏 − 𝐞−𝛌𝐭

23. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
23
Recorded
Minimum Cut
Set(s)
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Network Hydraulic
Reliability
Nodal Demand Allocation
Import Shape Files of
Selected Sub-Network
Required Demand
Service
Pressure Head
Available
Pressure Head
Pipe
Pipe IDDiameter Length
Start Node
End Node
Material
BreaksC Factor Age
Node
Node ID
Elevation
Feature Class Attribute
ArcGIS WaterCAD
Model Builder

24. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
24
Recorded
Minimum Cut
Set(s)
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Network Hydraulic
Reliability
Nodal Demand Allocation
Import Shape Files of
Selected Sub-Network
Required Demand
Service
Pressure Head
Available
Pressure Head
Unit Demand Control Center

25. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
25
Recorded
Minimum Cut
Set(s)
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Network Hydraulic
Reliability
Nodal Demand Allocation
Import Shape Files of
Selected Sub-Network
Required Demand
Service
Pressure Head
Available
Pressure Head
Normal Condition
• All segments are functional
• Satisfy nodal demands at required pressure
Failure Condition
• At-least one of the segments is non-functional
• Reduced level of water supply at nodes, partially fulfilling the customers’
demands

26. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
26
Recorded
Minimum Cut
Set(s)
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Network Hydraulic
Reliability
Nodal Demand Allocation
Import Shape Files of
Selected Sub-Network
Required Demand
Service
Pressure Head
Available
Pressure Head
Normal Condition
Failure Condition
(For all cut sets)
Hydraulic Simulation
AllSegments
are Functional
Run Hydraulic
Simulation
Required Pressure Head
Hreq
Recorded Cut Set(s) from
Mechanical Reliability Model
Recorded Cut Set(s) from
Hydraulic Reliability Model
Segment(s) are
Non-Functional
Run Hydraulic
Simulation
Available Pressure Head
Havl
Nodal Demand Allocation
Lreq

27. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
27
Recorded
Minimum Cut
Set(s)
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Network Hydraulic
Reliability
Nodal Demand Allocation
Import Shape Files of
Selected Sub-Network
Required Demand
Service
Pressure Head
Available
Pressure Head
𝐋 𝐚𝐯𝐥 = 𝟎
if 𝐇 𝐚𝐯𝐥 < 𝐇 𝐦𝐢𝐧
Hreq = Required pressure head at a node (m)
Havl = Available pressure head at a node (m)
Hmin & Hmax = Minimum and maximum
pressure head at a node respectively (m)
Lreq = Required demand at a node (m3/day)
Lavl = Available demand at a node (m3/day)
𝐋 𝐚𝐯𝐥 = 𝐋 𝐫𝐞𝐪
𝐇 𝐚𝐯𝐥−𝐇 𝐦𝐢𝐧
𝐇 𝐫𝐞𝐪−𝐇 𝐦𝐢𝐧
if 𝐇 𝐦𝐢𝐧 ≤ 𝐇 𝐚𝐯𝐥 ≤ 𝐇 𝐫𝐞𝐪
𝐋 𝐚𝐯𝐥 = 𝐋 𝐫𝐞𝐪
if 𝐇 𝐫𝐞𝐪 < 𝐇 𝐚𝐯𝐥 ≤ 𝐇 𝐦𝐚𝐱
𝐋 𝐚𝐯𝐥 = 𝟎
if 𝐇 𝐚𝐯𝐥 > 𝐇 𝐦𝐚𝐱

28. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
28
Recorded
Minimum Cut
Set(s)
Run Hydraulic
Simulation
Normal Condition
Failure Condition
(For all cut sets)
Available Demand
Network Hydraulic
Reliability
Nodal Demand Allocation
Import Shape Files of
Selected Sub-Network
Required Demand
Service
Pressure Head
Available
Pressure Head
𝐑 )𝐇(𝐱 =
𝐣=𝟏
𝐍 𝐍𝐨𝐝𝐞
𝐋𝐣 𝐚𝐯𝐥
𝐣=𝟏
𝐍 𝐍𝐨𝐝𝐞
𝐋𝐣 𝐫𝐞𝐪
Hydraulic
reliability of a
network/sub-
network in failure
condition x
𝐑 𝐍𝐇 =
𝐑 𝐇 𝐱
𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐌𝐢𝐧𝐢𝐦𝐮𝐦 𝐂𝐮𝐭 𝐒𝐞𝐭𝐬
Hydraulic
reliability of a
network/sub-
network

29. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
29
Integrated Network Reliability
𝐑 𝐍 =
𝐍𝐨. 𝐨𝐟 𝐬𝐭𝐫𝐮𝐜𝐭𝐮𝐫𝐚𝐥 𝐟𝐚𝐢𝐥𝐮𝐫𝐞𝐬 × 𝐑 𝐍𝐌 + 𝐍𝐨. 𝐨𝐟 𝐡𝐲𝐝𝐫𝐚𝐮𝐥𝐢𝐜 𝐟𝐚𝐢𝐥𝐮𝐫𝐞𝐬 × 𝐑 𝐍𝐇
𝐓𝐨𝐭𝐚𝐥 𝐧𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐟𝐚𝐢𝐥𝐮𝐫𝐞𝐬
RN = Integrated mechanical and hydraulic network reliability
RNM = Mechanical reliability of the network
RNH = Hydraulic reliability of the network
Causes of failures are based on NRC (2006) best practice
guide for assessing and reducing risks in drinking water
distribution systems

30. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
30
Data
Collection
Geo
database
Bentley
WaterCAD
Literature
Review
Best
Practice
Guide
 Hydrant demands
 Pressure limits
 Failure causes and
consequences
 Weight composition of
components in a segment
 City of London
 City of Doha
 Nodal demands

31. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
31
Literature Review
Component Weights (Salman, 2011)
Segment Water main component Weight (%)
Hypothetical
Pipe 38
Hydrant 31
Isolation Valve 28
Control Valve 3
Total 100

32. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
32
City of London
City of London Official Website (2015)

33. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
33
City of London
North Phase
South Phase

34. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
34
City of Doha

35. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
35
Best Practice Guides
• Causes and Consequences of
Failure
NRC (2006)
• Pressure Limits
Design Specification
and Requirements
Manual (2015)
• Hydrant Demands
Fire Underwriters
Survey (1999)

36. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
36
Bentley WaterCAD
Nodal Demand Allocation

37. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
37
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
Segment
Comp.
No.ofFailures
Age
(yrs)
Segment
Length(m)
Failurerate
(Breaks/m)
Comp.
Reliability
Weight
RelativeWeight
Segment
Reliability
Probabilityof
failureof
Segments
a
Pipe 1 0 84
153.33
0.0785 0.9245 0.38 0.58
0.9429 0.0571
Valve 1 5 0.0326 0.9679 0.28 0.42
City of London

38. Demand Node Possible Paths
4
{a,e,f}, {a,b,c}, {a,i,l,j,f}, {a,e,h,g,d}, {a,i,m,q,o,j,f}, {a,i,l,n,k,h,f}, {a,i,l,n,k,g,d}, {a,i,l,j,h,g,d}, {a,e,j,n,k,g,d},
{a,i,m,r,u,t,o,j,f}, {a,i,m,r,u,p,n,j,f}, {a,i,m,r,u,p,k,h,f}, {a,i,m,r,u,p,k,g,d}, {a,i,m,q,t,p,n,j,f}, {a,i,m,q,t,p,k,h,f},
{a,i,m,q,t,p,k,g,d}, {a,i,m,q,o,n,k,h,f}, {a,i,m,q,o,n,k,g,d}, {a,i,m,q,o,j,h,g,d}, {a,i,l,o,t,p,k,h,f}, {a,i,l,o,t,p,k,g,d},
{a,e,j,o,t,p,k,g,d}, {a,i,m,s,v,u,t,o,j,f}, {a,i,m,s,v,u,p,n,j,f}, {a,i,m,s,v,u,p,k,h,f}, {a,i,m,s,v,u,p,k,g,d},
{a,i,m,r,u,t,o,n,k,h,f}, {a,i,m,r,u,t,o,n,k,g,d}, {a,i,m,r,u,t,o,j,h,g,d}, {a,i,m,r,u,p,n,j,h,g,d}, {a,i,m,q,t,p,n,j,h,g,d},
{a,i,l,o,q,r,u,p,k,h,f}, {a,i,l,o,q,r,u,p,k,g,d}, {a,e,j,o,q,r,u,p,k,g,d}, {a,e,j,l,m,r,u,p,k,g,d}, {a,e,j,l,m,q,t,p,k,g,d},
{a,i,m,s,v,u,t,o,n,k,h,f}, {a,i,m,s,v,u,t,o,n,k,g,d}, {a,i,m,s,v,u,t,o,j,h,g,d}, {a,i,m,s,v,u,p,n,j,h,g,d},
{a,i,l,o,q,s,v,u,p,k,h,f}, {a,i,l,o,q,s,v,u,p,k,g,d}, {a,e,j,o,q,s,v,u,p,k,g,d}, {a,e,j,l,m,s,v,u,p,k,g,d}
Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
38
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
City of London
North Phase Sub-Network Model (Mathematica 10.2)

39. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
39
City of London
Path Matrix (Mathematica 10.2)

40. 40
Modified Path Matrix (MATLAB R2013b)

41. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
41
City of London
Order of Cut Sets List of Cut Sets
1 {a}
2 {b,c},{d,g},{s,v}
3
{b,d,f}, {b,e,i}, {b,f,g}, {c,d,f}, {c,e,i}, {c,f,g},
{d,h,k}, {g,h,k}, {i,j,k}, {i,l,m}, {k,n,p}, {m,q,u},
{o,q,t}, {p,t,u}, {r,s,u}, {r,u,v}
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
Applying the principle of minimum cut set method, the
mechanical reliability of the north phase sub-network is
calculated to be 0.94

42. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
42
City of London
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
North Phase Sub-Network Model (WaterCAD V8i)
Hydraulic Simulation of North Phase Sub-Network

43. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
43
City of London
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
Demand
Node
GIS ID Demand (m³/day) Pressure Head (m)
8 N4210 114 34.86
1 N5775 77.5 38.1
4 N5794 93 35.71
3 N5795 93 36
2 N5796 114 38.5
6 N5992 70 35.65
5 N6088 93 32.38
7 N6091 93 35.88
12 N6094 152 34.94
9 N6096 93 35.85
10 N6098 84 34.65
13 N6100 77.5 34.45
11 N6108 95 36.5
14 N6130 46.5 36.7
15 N6131 77.5 36.39
Service Pressure Heads
for Demand Nodes of
North Phase Sub-Network

44. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
44
City of London
Demand Node a closed b + c closed d + g closed s + v closed
8 0 32.73 34.59 34.86
1 38.1 38.1 38.1 38.1
4 0 32.69 35.94 35.71
3 0 0 36.16 36
2 0 38.5 38.5 38.5
6 0 33.31 35.7 35.65
5 0 29.71 0 32.38
7 0 33.56 35.56 35.88
12 0 32.7 34.66 34.94
9 0 33.61 35.57 35.85
10 0 32.35 34.34 34.65
13 0 32.21 34.16 34.45
11 0 34.27 36.21 36.5
14 0 34.47 36.41 36.7
15 0 34.17 36.11 0
Available Pressure Heads
at Demand Nodes of
North Phase Sub-Network

45. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
45
City of London
Available Nodal Demands
for North Phase Sub-
Network
Demand Node a closed b + c closed d + g closed s + v closed
8 0 94.66 111.73 114.00
1 77.5 77.50 77.50 77.50
4 0 72.53 93.00 93.00
3 0 0.00 93.00 93.00
2 0 114.00 114.00 114.00
6 0 58.32 70.00 70.00
5 0 58.11 0.00 93.00
7 0 78.12 91.09 93.00
12 0 125.09 148.90 152.00
9 0 78.62 91.33 93.00
10 0 67.94 82.02 84.00
13 0 62.61 75.74 77.50
11 0 81.59 93.37 95.00
14 0 40.10 45.72 46.50
15 0 66.46 76.20 0.00

46. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
46
City of London
After finding the available
demands at all nodes, the
hydraulic reliability of the selected
north phase sub-network is
calculated is found to be equal to
Demand Node a closed b + c closed d + g closed s + v closed
8 0 94.66 111.73 114.00
1 77.5 77.50 77.50 77.50
4 0 72.53 93.00 93.00
3 0 0.00 93.00 93.00
2 0 114.00 114.00 114.00
6 0 58.32 70.00 70.00
5 0 58.11 0.00 93.00
7 0 78.12 91.09 93.00
12 0 125.09 148.90 152.00
9 0 78.62 91.33 93.00
10 0 67.94 82.02 84.00
13 0 62.61 75.74 77.50
11 0 81.59 93.37 95.00
14 0 40.10 45.72 46.50
15 0 66.46 76.20 0.00
0.7062

47. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
47
City of London
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
40
15
13 13
30
21
0
5
10
15
20
25
30
35
40
45
Corrosion Permeation Pipe
Deterioration
Pipe
Deterioration
Hydraulic
Changes during
Maintenance and
Emergencies
Tuberculation
Mechanical Hydraulic
No.ofFailures
Failure Causes
51.51% 48.49%
The integrated reliability of the north phase sub-
network is assessed to be equal to 0.8255

48. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
48
Results
Sub-network
Mechanical
Reliability
Hydraulic
Reliability
Integrated
Reliability
North Phase 0.94 0.7062 0.8255
South Phase 0.9680 0.6958 0.8466
Qatar University 0.9689 0.6775 0.8471

49. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
49
Comparison of Results
The segment connecting the source of water to the network is the most
crucial segment of the network
Although all the minimum cut sets are crucial segments in a network, few
among them can be termed ‘more crucial’ than others
0.965 0.957 0.938
0.706
0.826
0.990 0.988 0.968
0.696
0.845
0.000
0.200
0.400
0.600
0.800
1.000
Average Component
Reliability
Average Segment
Reliability
Mechanical Reliability
of Sub-Network
Hydraulic Reliability of
Sub-Network
Integrated Network
Reliability
Reliability Comparison of Results
North Phase South Phase

50. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
50
Comparison of Results
0.965 0.957 0.938
0.706
0.826
0.990 0.988 0.968
0.696
0.845
0.000
0.200
0.400
0.600
0.800
1.000
Average Component
Reliability
Average Segment
Reliability
Mechanical Reliability
of Sub-Network
Hydraulic Reliability of
Sub-Network
Integrated Network
Reliability
Reliability Comparison of Results
North Phase South Phase
35.65
38.1
32.38
34.86
39.56
43.06
40.86
43.29
0
5
10
15
20
25
30
35
40
45
50
70 77.5 93 114
Pressure
m
Demand
m3/day
Required Pressure
North Phase vs South Phase
North Phase South Phase
South phase sub-network requires higher pressure than the
north phase, to supply equal demands of water
Elevation

51. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
51
Sensitivity Analysis
To study the behavior of pipes with different diameters in north and
south phases throughout their useful life
Simulated in normal condition by keeping all the properties of network as
constant except C factor and diameter
As the pipe ages, it gets tuberculated reducing the value of C factor
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 100
HydraulicReliability
% Reduction in C Factor
Sensitivity Analysis
North Phase vs South Phase
North Phase 150mm North Phase 200mm North Phase 250mm
South Phase 150mm South Phase 200mm South Phase 250mm
 Small diameter pipes are less
reliable than larger diameter pipes
 As the diameter of pipe gets
increased, the failure tendency gets
reduced and the pipes behave
likewise
 Pipes with same diameter
hydraulically performs better in
south phase sub-network in normal
condition

52. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation Conclusion
52
 Reliability indices provided at hierarchical levels of component, segment and network
 Algorithm of minimum cut set analysis of a network is extended to identify the minimum cut sets
for all demand nodes
 Mechanical reliability evaluation is automated to curtail its tediousness
 Hydraulic reliability of a water distribution network is evaluated considering the effect of pressure
 An integrated reliability assessment model is developed
Contribution

53. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation Conclusion
53
 Requires a detailed historic break data of all the components including pipes
 Failure rate of pipes is computed based only on their age
 Reliability is assessed without taking into consideration the effect of rehabilitation
 Hydraulic reliability is based on nodal demands that are calculated for an instant point
of time
Limitations

54. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation Conclusion
54
 Consider more factors to compute the failure rate of pipes
 Develop a failure rate prediction model for water distribution network components other than pipes
 Consider the effect of rehabilitation on reliability
 Investigate the nodal demands for identifying the demand multipliers to run extended period hydraulic
simulation
 Supplement with rehabilitation scheduling, budget allocation and life cycle cost models
 Integrate with reliability prediction models of other infrastructure by exploring interdependencies among them
Future Work

56. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
56
Best Practice Guides
Types of failures Causes Consequences
Mechanical
 Corrosion
 Permeation
 Failure due to aging and weathering
 Contamination of Mains, Fittings, and
Appurtenances
 Contamination of Storage Facilities
 Contamination Due to the Absence or
Operational Failure of Backflow
Prevention Devices
Hydraulic
 Pipe Deterioration
 Hydraulic Changes during Maintenance
and Emergencies
 Tuberculation and Scale
 External Contamination
 Sedimentation
 Reduction in Hydraulic Capacity and
Associated Increase in Pumping Costs
(NRC, 2006)

57. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
57
City of London
Case Studies
London Doha
South Phase
North Phase
Mechanical Reliability Model
Hydraulic Reliability Model
Integrated Network
Reliability
Demand
Node
GIS ID Demand (m³/day)
Pressure Head
(m)
10 N10333 70 39.56
7 N11569 124 37.86
4 N11570 62 34.55
3 N11594 114 40.66
2 N11596 57 43.59
1 N11638 62 41.9
11 N16836 77.5 43.06
12 N16837 114 40.51
13 N16839 133 39.94
8 N16841 10 43.96
5 N16844 114 43.29
9 N16846 62 41.56
6 N16849 76 41.09
Service Pressure Heads for
Demand Nodes of South Phase
Sub-Network

58. Introduction
Literature
Review
Research
Methodology
Data
Collection
Model
Implementation
Conclusion
58
City of London
Available Pressure Heads at
Demand Nodes of South Phase
Sub-Network
Demand
Node
a closed
b + d
closed
c + g
closed
n + q
closed
10 0.00 0.00 39.48 39.56
7 0.00 0.00 37.76 37.86
4 0.00 0.00 0.00 34.55
3 0.00 0.00 40.67 40.66
2 0.00 43.59 43.59 43.59
1 41.90 41.90 41.90 41.90
11 0.00 0.00 42.97 0.00
12 0.00 0.00 40.43 40.50
13 0.00 0.00 39.86 39.93
8 0.00 0.00 43.88 43.97
5 0.00 0.00 43.22 43.29
9 0.00 0.00 41.48 41.56
6 0.00 0.00 41.01 41.09