Robust technology and policy pathways to urban water security

Increasingly frequent and severe droughts are jeopardizing urban water security in water stressed regions, but cities also struggle to justify the costs and energy consumption of some drought-resilient technologies. 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 modeling framework that captures the complex system dynamics that link climate impacts to household water security. A robust, multi-objective, evolutionary-based optimization framework (i.e., EMODPS) 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 urban water resource planners, as well as guides technology innovation by explicitly valuing technology attributes that enable resilience to droughts of varying duration, severity, and intensity. 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.