[Resilience and Risk of Failure of Water Distribution Systems through Novel Complex Network Analysis]

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Acknowledgement

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

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I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

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Abstract

Planners and engineers attempting to improve the resilience of water distribution systems face numerous challenges regarding the allocation and placement of redundancy so as to reduce the likelihood and impact of asset failures and take into consideration the growing demand for clean water, now and into the future. Water distribution systems may be represented as networks of multiple nodes (e.g. reservoirs, storage tanks and hydraulic junctions) interconnected by physical links (e.g. pipes) where the connectivity patterns of this network affects its reliability, efficiency and robustness to failures. In this thesis we employ the link-node representation of water infrastructures and exploit a wide range of advanced and emerging network theory metrics and measurements to study the building blocks of the systems and quantify properties such as redundancy and fault tolerance, in order to establish relationships between structural features and performance of water distribution systems. We study the water distribution network of a growing city from a developing country and explore network expansion strategies that are aimed to secure and promote structural invulnerability, subject to design and budget constraints.

Table of Contents

CHAPTER 1: INTRODUCTION6

Thesis Organization6

CHAPTER 2: LITERATURE REVIEW8

Network characteristics and measurements8

CHAPTER 3: CASE STUDIES AND METHODOLOGY11

REFERENCES13

Chapter 1: Introduction

Increasing water stress in many developing countries both endangers lives and restricts economic growth. Although levels of access to a piped water distribution are increasing at a global level, many of the developing world's cities are served by old and poorly maintained networks with consequential problems in terms of both water quality and supply reliability (UNDP, 2006). The problem is compounded by the increasing frequency and scale of extreme natural events and man-made catastrophes that cause major flow disruptions. Like many other infrastructural systems, water distribution systems consist of multiple interconnected components, whose individual or simultaneous failure may have adverse consequences in terms of disruption to water services.

Therefore, improving system reliability and reducing system susceptibility to damage and perturbation are prime concerns for system engineers and utility managers responsible for the design, operation and protection of the Water Distribution Networks (WDN).

Thesis Organization

This thesis is organized as follows. First, we briefly introduce some graph theory metrics and measurements and explain how they might be interpreted and used to capture qualities such as redundancy, optimal connectivity and structural robustness. Second, we study the structure of the water distribution network of Kumasi (Ghana's second largest city), quantify its connectivity and redundancy and explore the relationship of these metrics to the network's structural invulnerability and ...