Author(s): M. Zaniolo; S. Fletcher; M. Mauter
Keywords: Decision-making under uncertainty; Smart urban water management; Drought management
Abstract: Increasingly frequent and severe droughts are straining municipal water resources and jeopardizing urban water security. However, the length and severity of droughts are unknown in advance, challenging short-term drought response, midterm infrastructure planning, and long-term technology innovation investment. Previous literature in urban water modeling developed strategies to expand and diversify urban water supply portfolios to enhance water resilience cost effectively. This literature has also demonstrated that high-resolution, household-level modeling is necessary to represent the real energy footprint of different water technologies and the integration of centralized and decentralized water solutions. This urban-focused modeling scale, however, does not support the characterization of water availability at extra-urban sources resulting from watershed-wide hydrological processes. Conversely, watershed-scale water resources planning characterizes water variability and stress, supports climate change analysis, but overlooks key distributional and technological aspects. This project develops a watershed-to-end-user decision support tool for cost-effective, adaptive water augmentation pathways to ensure robustness in many climate futures. The novelty of our work lies in a true multiscale framework that captures the complex system dynamics that link climate impacts to household water security (Fig. 1). A robust, multiobjective, evolutionary-based optimization framework is used to derive the technology portfolio, deployment location, and construction timing that defines a city’s Pareto frontier of water resilience and cost. This work informs generalizable guidelines for effective water supply augmentation in an uncertain climate, for instance demonstrating the advantages of small, incremental, investments to building resilience in response to water stress, over large-scale concentrated capacity expansions. Results guide technology innovation investments for municipal water treatment by explicitly valuing technology attributes that enable resilience to water shortages of varying duration, severity, and intensity, bridging the gap between hydrological prediction and technology innovation. We apply this model to the City of Santa Barbara, California, given the time relevance to city planning efforts, the diversified water supply mix, and the relative isolation of the community, enclosed between the ocean and a mountain range.