Advancing combined water supply and demand planning and management under climatic and socio-economic change

With climate change increasing the stress on water resources and aging water infrastructure needing replacement in the Western United States, water utilities are tasked with planning and managing an increasingly complex water system to meet key objectives such as water security, drought resilience, affordability, and equitable access to water. However, they still often rely on simple assumptions to model their water resource systems, and changes in management practices are often implemented reactively, in response to changing external conditions, instead of proactively. The main goal of this thesis is to advance and develop analytic frameworks and modeling tools to facilitate the analysis of combined water supply and demand planning and management strategies and drought-resilient adaptive water resource planning at the state-wide scale of California, USA, to ultimately formulate future policy recommendations. The contribution of this thesis is threefold. First, we contribute an open-access dataset which encompasses nine years (2013-2021) of monthly time series of residential water supply and demand data for 404 water suppliers in California. Second, we develop a three-step descriptive analytics framework powered by explainable artificial intelligence to assess the influence of climate, regional, institutional, and socio-economic factors on combined water supply and demand management patterns. Third, we generalize a state-of-the-art adaptive water resource planning tool that includes multiple, scalable water augmentation and demand options, to provide state-wide drought resilience planning and management recommendations. We find that in times of drought and pandemic in California either water supply operations promptly adapted to changes in water demand, or combined water supply and demand management strategies have been implemented effectively and in a coordinated way. Further, our retrospective results indicate that combined water supply and demand management strategies can foster more equal usage of water resources across California. For the optimal state-wide, drought resilient combined water supply and demand planning and management portfolio, we find that drought characteristics influence planning decisions as well as the available water sources of a water utility. Also, our results show that technological advances such as decentralized water reuse can significantly reduce planning costs. These findings reinforce the call from previous research that state-wide water policies need to be more flexible, accounting for water utility features, e.g., size, region, and storage capacities.