| Description |
Addressing the urgency of aging water infrastructure, this dissertation introduces a new approach to aid the planning for sustainability of a water distribution network. The majority of water distribution systems (WDSs) in the United States (US) were constructed before 1945, and a major fraction of the assets are reaching the end of their useful life. Repairing and replacing assets can address the problem and cost minimization is the typical approach to guide this asset management. However, basing planning exclusively on cost minimization neglects important factors related to environment and society. Moreover, the past approaches have not solved the aging problem as indicated by recent D/D- grades on the ASCE Infrastructure Report Cards. The overarching goal of this dissertation is to advance WDS asset management using a sustainability-based analysis framework. To achieve this goal, a triple top line (TTL) approach is adopted as a tool for WDS sustainability evaluation using hydraulic network modeling. First, metrics for the TTL factors are developed; they are combined into a sustainability index (SI), and tested using EPANET hydraulic simulations of a hypothetical WDS subjected to multiple aging scenarios. Second, the sustainable life of pipe (SLP) is determined to prioritize pipe replacement timing to maximize the sustainability of a WDS. And third, a hybrid combination of a hydraulic model and system dynamics model (H-SD) is developed to support financial planning of a WDS. Applications to a WDS are used to test the effectiveness of the analysis approach and hybrid model. iv The results of an aging scenario confirmed the expectation of age influencing the SI. Sensitivity analysis further illustrated that pipe aging, demand increase, water price reduction, and pipe breakage all reduced sustainability. The SLP results illustrated that maximizing the SI of the WDS leads to earlier pipe replacement with increased benefits compared to basing pipe replacement on cost minimization. Also providing a 1% annual rate of demand growth as a conservation target maximizes the SI. The H-SD model highlighted the importance of water price elasticity (WPE) for estimation of revenue. Also, the results confirmed aggressive water pricing to increase revenue does not guarantee higher SI. The final demonstration shows that a more frequent, lower incremental water price increase is more favorable when a higher WPE is present. In summary, this dissertation concluded: (1) The TTL model reflected the expected change of sustainability and is able to provide useful insight into sustainability for planning, design, and operations comparative analyses; (2) the TTL-based SI can guide demand management and pipe replacement strategies to maximize a comprehensive set of sustainability benefits; and (3) the H-SD model can project reasonable funding requirements by determining an affordable water price increase for customers while improving the sustainability of the WDS. First and foremost, I want to dedicate my dissertation work, with special feelings of gratitude and deepest love, to my loving wife, Minjung. Thank you for being a constant source of rest and encouragement during the challenges of Ph.D. study. I have truly relied on your endless support and intellectual stimulation. To my parents, Hong-Hee and Hye-Sook, deepest gratitude for always loving me unconditionally, and being a source of encouragement and inspiration to me throughout my life. I thank you for all your support and prayer during my study. I also want to thank my parents-in-law, Deuk-Yong and Bu-Suk, for their endless support, and kind prayer to finish never easy work for me and my wife. I thank you for your understanding and patience during my study. Finally, I dedicate this dissertation to my loving kids, Junwoo, Jia, and Coco who will born soon. |
