UBC Theses and Dissertations
Water distribution system failures : an integrated framework for prognostic and diagnostic analyses Islam, Mohammad Shafiqul
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.
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