WATER DISTRIBUTION SYSTEM FAILURES

215 Pages·2012·3.7 MB·English

by  M. Shafiqul Islam

WATER DISTRIBUTION SYSTEM FAILURES: AN INTEGRATED FRAMEWORK
FOR PROGNOSTIC AND DIAGNOSTIC ANALYSES

by

Mohammad Shafiqul Islam

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

in

The College of Graduate Studies
(Civil Engineering)

THE UNIVERSITY OF BRITISH COLUMBIA
(Okanagan)

November 2012

© Mohammad Shafiqul Islam, 2012
ABSTRACT

The main goal of this research is to develop an integrated decision support system framework for
prognostic and diagnostic analyses of water distribution system (WDS) failures. The
interventions based on the prognostic analysis will reduce the likelihood of failures, and in case
of a failure, will minimize the consequences of the failures. The framework consists of five novel
models. For prognostic analysis, the first model evaluates the reliability of WDS in terms of
utility and belief of the estimated utility. This model provides a measure of degree of
uncertainties in reliability estimation and helps to plan and design a reliable WDS. Based on
various influencing factors, the leakage potential model evaluates potential for leakage under
varying operating conditions. Based on identified symptoms of failure such as taste and odor, and
the causes of failure such as free residual chlorine, the water quality failure potential model
evaluates the potential for water quality failure (WQF).
For diagnostic investigation, the leakage location and detection model, the fourth model,
identifies the presence of an actual leakage, if any, and the most probable leakage location in
WDS. The WQF detection model, the fifth model, identifies the most vulnerable location in the
WDS and in case of failure, identifies the most probable reason and most probable source of
water quality failure.
Finally, based on the developed models and other external information, an integrated prognostic
and diagnostic decision support system framework has been developed. The prognostic
capabilities of the framework provide states of the WDS and evaluate failure potentials of the
system. The diagnostic capabilities of the framework help to reduce false positive and false
negative predictions, and identify the failure location with minimal time after the occurrence
which minimizes the consequences of failure. The framework has ‘unique’ capacity to bring the
modelling information (hydraulic and Quality), consumer complaints and laboratory test
information under a single platform. The outcomes of this research widely addressed the
uncertainties associated with WDS which improves the efficiency and effectiveness of diagnosis
and prognosis analyses of WDS failures. The research also provides new insights on how to
incorporate fuzzy set in the assessment of WDS failures. It is expected that the developed
integrated framework will help municipalities to make informed decisions to increase the safely
and the security of public health.
ii
PREFACE

I, Mohammad Shafiqul Islam, conceived and developed all the contents in this thesis under the
supervision of Dr. Rehan Sadiq. The other coauthors of the articles based on this thesis, Dr. Alex
Francisque, Dr. Manuel J. Rodriguez, Dr. Homayoun Najjaran and Dr. Mina Hoorfar, have
reviewed all the manuscripts prepared and provided critical feedback to improve the quality of
the manuscripts and thesis. Most of the contents of this thesis are published, accepted or
submitted for publication in scientific international journals and conferences.
 A version of Chapter 2 has been submitted for publication in The special issue of the
Journal of Tunnelling and Underground Space Technology (TUST) incorporating
Trenchless Technology Research with the title “Water Distribution System Failure: A
Forensic Analysis” (Islam et al. 2011a). This article is under second review.
 A version of Chapter 3 has been submitted for publication in ASCE Journal of Water
Resources Planning and Management with the title “Reliability Assessment for Water
Supply Systems: A Novel Methodology” (Islam et al. 2012b). This paper is under second
review.
 A version of Chapter 4 has been published in Journal of Water Supply: Research and
Technology – AQUA with the title “Evaluating Leakage Potential in Water Distribution
Systems: A Fuzzy-Based Methodology”(Islam et al. 2012a).
 A version of Chapter 5 has been published in The Urban Water Journal with the title
“Leakage Detection and Location in Water Distribution System using a Fuzzy-Based
Methodology” (Islam et al. 2011b).
 A version of Chapter 6 has been submitted for publication in Water Resource
Management with the title “Evaluating Water Quality Failure Potential in Water
Distribution Systems: A Fuzzy-TOPSIS-OWA Based Methodology” (Islam et al. 2011c).
 Some portions of Chapter 4 and Chapter 5 have been published in The Proceedings of the
20th Canadian Hydrotechnical CSCE Conference (2011) with the title “Leakage Forensic
Analysis for Water Distribution Systems: A Fuzzy-Based Methodology” (Islam et al.
2011d).

iii
TABLE OF CONTENTS

Abstract ................................................................................................................................................... ii
Preface .................................................................................................................................................... iii
Table of Contents ................................................................................................................................... iv
List of Tables......................................................................................................................................... vii
List of Figures ........................................................................................................................................ ix
List of Abbreviations ............................................................................................................................. xii
List of Symbols .................................................................................................................................... xiv
Acknowledgements .............................................................................................................................. xvi
Dedication ........................................................................................................................................... xvii
Chapter 1 INTRODUCTION ...............................................................................................................1
1.1 Background and Motivation ....................................................................................................1
1.2 Research Objectives ................................................................................................................6
1.3 Thesis Organization ................................................................................................................8
Chapter 2 LITERATURE REVIEW AND PROPOSED FRAMEWORK ..........................................9
2.1 Literature Review ....................................................................................................................9
2.1.1 Basic Definitions in the Context of WDS Modelling ......................................................9
2.1.2 Risk-based WDS Modelling ......................................................................................... 10
2.1.3 Common Tools for WDS Modelling ............................................................................ 12
2.1.4 Multicriteria Decision Analysis (MCDA) Techniques................................................. 13
2.1.5 Uncertainty in WDS Modelling ................................................................................... 14
2.1.6 Water Distribution System Failure ............................................................................... 16
2.2 Proposed Framework ........................................................................................................... 19
2.2.1 Reliability Assessment Model ...................................................................................... 22
2.2.2 Leakage Potential Model .............................................................................................. 23
2.2.3 Leakage Detection and Location Model ...................................................................... 23
2.2.4 WQF Potential Model .................................................................................................. 23
2.2.5 WQF Detection and Diagnosis Model ......................................................................... 24
Chapter 3 RELIABILITY ASSESSMENT MODEL ....................................................................... 25
3.1 Background .......................................................................................................................... 25
3.2 Proposed Methodology ........................................................................................................ 30
3.2.1 Identification and Fuzzification of Independent Parameters ........................................ 33
3.2.2 Estimation of Extreme Values of Dependent Parameters ............................................ 35
3.2.3 Reliability Estimation ................................................................................................... 37
iv
3.3 Model Implementation and Demonstration .......................................................................... 48
3.4 Results and Discussion ......................................................................................................... 51
3.5 Summary .............................................................................................................................. 55
Chapter 4 LEAKAGE POTENTIAL MODEL ................................................................................ 57
4.1 Background .......................................................................................................................... 57
4.2 Leakage Potential Model Development Methodology ......................................................... 59
4.2.1 Model Framework ........................................................................................................ 59
4.2.2 Fuzzy Rule Based (FRB) Modelling ............................................................................ 62
4.2.3 Pressure Adjustment ..................................................................................................... 68
4.3 Example Evaluation of Leakage Potential ........................................................................... 71
4.4 Application of Proposed Leakage Potential Model .............................................................. 76
4.4.1 Study Area– Bangkok’s Metropolitan Water Authority .............................................. 76
4.4.2 Data Collection ............................................................................................................. 78
4.4.3 Results and Discussion ................................................................................................. 81
4.4.4 Sensitivity Analysis ...................................................................................................... 83
4.5 Model Summary ................................................................................................................... 91
Chapter 5 LEAKAGE DETECTION AND LOCATION MODEL ................................................. 92
5.1 Background .......................................................................................................................... 92
5.2 Leakage Detection and Location Model Development Methodology ................................. 95
5.2.1 Identification and Fuzzification of Independent Parameters ........................................ 97
5.2.2 Estimation of Extreme Values of Dependent Parameters ............................................ 98
5.2.3 Leakage Detection ...................................................................................................... 100
5.2.4 Node and Pipe Identification ...................................................................................... 102
5.3 Model Implementation ....................................................................................................... 104
5.3.1 Leakage Data Preparation .......................................................................................... 105
5.3.2 Leakage Detection ...................................................................................................... 106
5.3.3 Leakage Location ....................................................................................................... 107
5.4 Summary ............................................................................................................................ 110
Chapter 6 WATER QUALITY FAILURE POTENTIAL MODEL ............................................... 112
6.1 Background ........................................................................................................................ 112
6.2 Materials and Methods ....................................................................................................... 114
6.3 Full Scale Model Development and Application ............................................................... 125
6.4 Results and Discussion ....................................................................................................... 134
6.5 Summary ............................................................................................................................ 138
Chapter 7 WATER QUALITY FAILURE DETECTIONAND LOCATION MODEL................. 139
7.1 Background ........................................................................................................................ 139
v
7.2 Materials and Methods ....................................................................................................... 141
7.2.1 Data Collection ........................................................................................................... 142
7.2.2 Hydraulic and Water Quality Model Development ................................................... 142
7.2.3 WQF potential Model development ........................................................................... 144
7.2.4 WQF Detection .......................................................................................................... 144
7.2.5 Source Tracking Using PEST .................................................................................... 144
7.2.6 Severely Affected Area Identification ........................................................................ 147
7.3 Model Implementation ....................................................................................................... 148
7.3.1 Modelling of Fate of Arsenic in WDS ....................................................................... 149
7.3.2 Water Quality Event Data Preparation ....................................................................... 152
7.3.3 WQF Detection and Source Tracking Using PEST ................................................... 153
7.3.4 Identification of the Most Severely affected Area in WDS ....................................... 154
7.4 Model Summary ................................................................................................................. 154
Chapter 8 INTEGRATED DICISION SUPPORT SYSTEM ........................................................ 156
8.1 Background ........................................................................................................................ 156
8.2 Framework Integration ....................................................................................................... 156
8.3 Equivalent on Spot Complaint (ESC) ................................................................................ 159
8.4 Equivalent Illness Complaints (EIC) .................................................................................. 160
8.5 Dempster–Shafer Theory ................................................................................................... 160
8.5.1 Estimation of BPAs .................................................................................................... 161
8.5.2 Rules of Combination................................................................................................. 165
8.6 Implementation of Decision Support System ..................................................................... 166
8.6.1 Data Preparation ......................................................................................................... 166
8.6.2 Estimation of BPAs .................................................................................................... 169
8.6.3 Results and Discussion ............................................................................................... 170
8.7 Summary ............................................................................................................................ 177
Chapter 9 CONCLUSIONS AND RECOMMENDATIONS ......................................................... 178
9.1 Conclusions ........................................................................................................................ 178
9.2 Limitations and Recommendations .................................................................................... 180
9.2.1 Proposed Framework.................................................................................................. 180
9.2.2 Developed Models...................................................................................................... 181
9.2.3 Decision Support System ........................................................................................... 182
Bibliography ....................................................................................................................................... 185

vi
LIST OF TABLES

Table 1.1: Number of WDS with different types of advisories in a typical day (24th August,
2011) in Canada (Water 2011) ................................................................................. 4
Table 2.1: Application of risk-based water distribution modelling ......................................... 11
Table 2.2: Key features of different WDS modelling software ............................................... 12
Table 2.3: Key MCDA Techniques ......................................................................................... 13
Table 2.4: Sources of uncertainty in water distribution system modelling ............................. 14
Table 2.5: Common techniques used for uncertainty quantification and propagation ............ 15
Table 2.6: Comparison of accident and emergency (A&E) and proposed framework ........... 20
Table 3.1: Information of the example WSS ........................................................................... 27
Table 3.2: Model results for normal and changed conditions ................................................. 28
Table 3.3: Maximum, most likely & minimum pressure values at different nodes ................ 37
Table 3.4: EPS reliability results for Node D of the example network ................................... 45
Table 3.5: System utility for Example WSS ............................................................................ 48
Table 3.6 : Information of the example WDS ......................................................................... 50
Table 3.7: EPS reliability results for Node 27 of the example network .................................. 54
Table 4.1: Fuzzy sets and linguistic definition of input parameters ........................................ 63
Table 4.2: Study area at a glance ............................................................................................. 79
Table 4.3: Data used for the modelling of LP for the study area............................................. 80
Table 4.4: Definition of scenarios analyzed ............................................................................ 84
Table 5.1: Importance of time and technology in leakage (Modified from Lambert 1994) .... 93
Table 5.2: Typical degrees of leakage memberships and the associated ILPs ...................... 106
Table 5.3: Identification of the most likely leaky nodes and pipes in order .......................... 108
Table 5.4: Degree of leakage membership for a small leak at node 13 ................................. 108
Table 6.1: Definition of linguistic evaluation ........................................................................ 115
Table 6.2: Importance weights of criteria .............................................................................. 117
Table 6.3: Dynamic systems for experts’ opinion ................................................................. 117
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Table 6.4: Rating of the alternatives ...................................................................................... 118
Table 6.5: Aggregated fuzzy weight of criteria and rating of alternatives ............................ 120
Table 6.6: Fuzzy normalized decision matrix........................................................................ 121
Table 6.7: Fuzzy weighted normalized decision matrix ........................................................ 121
Table 6.8: Summary description of the causes and the symptoms for the WQF ................... 125
Table 6.9: Recommended values of the causes and the symptoms........................................ 129
Table 6.10: Data used for the modelling of WQF potential for the study area ..................... 130
Table 6.11: Data used for overall WQF potential evaluation ................................................ 132
Table 8.1: Different phases of Integration ............................................................................. 162
Table 8.2: Primary data used in the integration phase ........................................................... 167
Table 8.3: Non-zero primary data under failure condition .................................................... 168
Table 8.4: Assumed constants to convert ESC & EIC .......................................................... 169
Table 8.5: Controlling parameters for normalization and BPAs estimation ......................... 169
Table 8.6: Hydraulic prognosis results of top four likely pipes (in order) under normal
condition .............................................................................................................. 171
Table 8.7: Hydraulic prognosis results of top four likely pipes in order under failure
condition ............................................................................................................... 171
Table 8.8: Hydraulic diagnosis results of top four likely nodes (in order) under normal
condition ............................................................................................................... 172
Table 8.9: Hydraulic prognosis results of top four likely nodes (in order) under failure
condition ............................................................................................................... 172
Table 8.10: Water quality prognosis results of top four likely nodes (in order) under
normal condition ................................................................................................... 175
Table 8.11: Water quality prognosis results of top four likely nodes (in order) under
minor changes in WQF potentials ........................................................................ 175
Table 8.12: Water quality diagnosis results of top four likely nodes (in order) under
normal condition ................................................................................................... 176
Table 8.13: Water quality diagnosis results of top four likely nodes (in order) under
failure condition .................................................................................................... 176

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LIST OF FIGURES

Figure 1.1: NRW in some of the Asian Cities (ADB & IWP 2010) ......................................... 2
Figure 1.2: Thesis structure and organization............................................................................ 7
Figure 2.1: Flow chart of the proposed framework (Bold outlined blocks relate to major
objectives) ............................................................................................................... 21
Figure 3.1: Layout of the example network............................................................................. 27
Figure 3.2: Reliability assessment methodology ..................................................................... 30
Figure 3.3: Conceptual framework of the belief estimation .................................................... 32
Figure 3.4: Triangular and trapezoidal fuzzy numbers ............................................................ 34
Figure 3.5: Distribution of pressure utility .............................................................................. 38
Figure 3.6: Distribution of water quality utility....................................................................... 40
Figure 3.7: General solution domain ....................................................................................... 43
Figure 3.8: Hydraulic reliability at Node D under different level of uncertainties ................. 44
Figure 3.9: Layout of the study example WDS (pipe length not to the scale) ........................ 49
Figure 3.10: Available pressure at critical point under critical pipe failure condition ............ 53
Figure 4.1: Hierarchical structure of selected leakage influencing factors ............................. 60
Figure 4.2: Information flow in FRB modelling ..................................................................... 62
Figure 4.3: Five level granularity of fuzzy numbers ............................................................... 64
Figure 4.4: LP evaluation considering only the pressure as an influencing factor .................. 70
Figure 4.5: Input and output fuzzy membership functions for pressure dependent
SISO model ............................................................................................................. 71
Figure 4.6: Rules evaluation and outputs for RP and SP ......................................................... 72
Figure 4.7: Input and output membership function for MISO model...................................... 73
Figure 4.8: Rules evaluation and outputs for NM, NS and NJ ................................................ 74
Figure 4.9: MWA service area................................................................................................. 77
Figure 4.10: Network layout for DMA-00144 ........................................................................ 77
Figure 4.11: Typical pipe trench in the study area .................................................................. 79
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Figure 4.12: LP with varying pressure .................................................................................... 81
Figure 4.13: LP with age for two different operating system pressures .................................. 82
Figure 4.14: MC simulation results for Scenario I (a) PDF and CDF (b) Spearman rank
correlation coefficients ........................................................................................... 85
Figure 4.15: MC simulation results for Scenario II (a) PDF and CDF (b) Spearman rank
correlation coefficients ........................................................................................... 87
Figure 4.16: MC simulation results for Scenario III (a) PDF and CDF (b) Spearman rank
correlation coefficients ........................................................................................... 89
Figure 4.17: MC simulation results for Scenario IV (a) PDF and CDF (b) Spearman rank
correlation coefficients ........................................................................................... 90
Figure 5.1: Conceptual framework of the proposed methodology .......................................... 96
Figure 5.2: Flowchart for proposed methodology ................................................................... 99
Figure 5.3: Leakage detection algorithm ............................................................................... 101
Figure 5.4: ILPs at different nodes (different color represents ILPs in different nodes)....... 107
Figure 5.5: Deviations of ILPs at Sensor at Node No. 19 over time (limited number of
sensors) ................................................................................................................. 109
Figure 5.6: Deviations of ILPs at Sensor at Node No. 17 over time for a small leak ........... 109
Figure 6.1: Conceptual methodology for the development of WQF potential model ........... 114
Figure 6.2: Interrelationship of different causes and symptoms ............................................ 116
Figure 6.3: Interrelation of different criteria (symptoms) and alternatives (causes).............. 128
Figure 6.4: WQF potential in different zones of Quebec City WDS..................................... 133
Figure 6.5: Comparative influences of different causes to the WQF potential ..................... 134
Figure 6.6: MC simulation results ......................................................................................... 136
Figure 6.7: MC simulation results: percent contribution of WQF causes ............................. 137
Figure 7.1: Different components of Water Quality Failure Time ........................................ 140
Figure 7.2: Overview of the proposed methodology ............................................................. 141
Figure 7.3: Conservation of mass (a) and energy (b) (FL=Flow; ND= Nodal demand;
V=Velocity; Z= Elevation head; h = Head added by the pump) .......................... 142
p
Figure 7.4: Work flow of PEST optimization ....................................................................... 145
x