The impact of contextual factors on the predicted bulk water pipe repair times in Wellington City : a thesis presented in partial fulfilment of the requirements for the degree of Master in Emergency Management at Massey University, Wellington, New Zealand
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Date
2017
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Massey University
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Abstract
Lifelines, like the water supply, are essential for the survival of people, communities, and
businesses. In the event of a significant natural disaster, like an earthquake, it can be
expected that these regional lifelines will be severely damaged. Wellington, the capital of
New Zealand, contains many lifelines that are highly vulnerable to failure. The water
supply is especially susceptible, as it crosses the Wellington Fault multiple times and
carries water through landslide prone corridors. Because of the risk, and potential impact
on people, several predictive models have been created to calculate the likely downtimes
so individuals and organisations can prepare for the loss. Many of these predictive models
are comprehensive in what they calculate. However, they require improvement as they do
not include local and contextual factors or the influence of other lifelines. For example,
they do not include the impact of staff logistics, assume access to required equipment is a
given, and ignore interdependencies between lifelines, such as the loss of access to repair
sites because of damage to the transportation network.
This research aims to improve these current models by investigating the magnitude of
these site-specific and interdependency factors. Following a sequential mixed methods
approach and using a pragmatic viewpoint, experts directly involved in the repair and
maintenance of lifelines were selected for interviews. In total 20 professionals were
contacted using a snowball and convenience sampling technique. Out of these 20, five
were available for in-depth semi-structured phone interviews. From these interviews,
anything stated to affect the repair times was highlighted, the most prominent of which
were incorporated into current predictive models and their influence on repair times
calculated. In total 12 different issues were discussed, 4 of which were examined further.
These factors were: staff logistical problems; the slope of the land affecting damage
inspection processes; the impact of uncommon pipe diameters on the repair process; and
access problems. Once identified, these factors were incorporated into current predictive
models, and the impact on repair times calculated. By including these contextual
influences, it was found that they increased repair times by between 3 and 13 days
depending on the water source and 31 and 111 days when incorporating the influence of
landslides. Thus, proving contextual influences have a significant impact on repair times.
Overall this study 1) revealed the importance of including contextual factors into
predictive calculations and 2) created more accurate downtime predictions for the water
supply in Wellington City, allowing for people, organisations, and planners to better
prepare for the potential risk.
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Keywords
Water-pipes, Water-supply, Repairing, Earthquake effects, Computer simulation, Wellington, New Zealand, Research Subject Categories::SOCIAL SCIENCES::Business and economics::Business studies