Advancing Regional Water Supply Portfolio Management and Cooperative Infrastructure Investment Pathways under Deep Uncertainty

Abstract

Water utilities globally are facing a great pressure to proactively address growing demands, higher levels of resource contention, and increasingly uncertain water availability. A tension exists between improving the efficiency and coordination of regional water supplies to delay or eliminate major infrastructure investments and the eventual effects of demand growth rates that necessitate water supply capacity expansions. The hard- and soft-path views for urban water portfolio planning, namely infrastructure construction and efficient regionally-coordinated management (e.g., restrictions, water transfers, financial instruments, etc.), should be integrated while minimizing costly and contentious infrastructure expansion. However, both the soft and hard approaches may be detrimental to utilitiesThis ' finances. Integrating long-term water infrastructure investment and short-term management is a difficult task because of the potentially large number of decisions that must be considered over decadal timescales as well as the significant uncertainties inherent to the problem. This dissertation contributes a new uncertainty-sampling formulation for the stochastic simulation and optimization of water-infrastructure management policies (soft path alone) for regionally-coordinated water utilities. This sampling formulation accounts not only for well-characterized uncertainties, usually hydrological or climate extremes, but also for key urban-systems factors such as demand growth, effectiveness of water-use restrictions, construction costs, and financing uncertainties. This sampling scheme is later integrated into WaterPaths, a generalizable, cloud-compatible, open-source exploratory modeling framework designed to simulate and inform long-term regional investments in water infrastructure while simultaneously aiding regions to improve their short-term weekly management decisions. Uniquely, WaterPaths has the capability to identify the challenges and demonstrate the benefits of regionally-coordinated planning and management based on risk-of-failure decision metrics for groups of water utilities sharing water resources. The WaterPaths platform is introduced here through the hypothetical and realistic Sedento Valley test case, a test case designed to serve as a universal test case for decision-making frameworks and water-resources systems simulation software. Lastly, WaterPaths is integrated into the Deep Uncertainty (DU) Pathways framework. The DU Pathways framework is a decision-making framework developed for bridging long-term water supply infrastructure investments and improved short-term water portfolio management to yield robust regional water supply. The DU Pathways framework allows for elaborate uncertainty analysis to clarify how uncertainty may determine the appropriateness of infrastructure construction and the effectiveness of supply and financial drought-mitigation instruments used by regionally-coordinated water utilities. The ultimate goal of the DU Pathways is to aid stakeholders in discovering pathway policies that attain high performance levels across challenging and deeply uncertain futures and to guide robustness compromises that may be necessary between regional actors. As demonstrated in the Research Triangle region in North Carolina, DU Pathways clarifies how to identify robust infrastructure investment and management policies across the municipalities of Raleigh, Durham, Cary, and Chapel Hill.