New methods for identifying robust long-term water resources management strategies for California

Assuring sufficient, high-quality water supplies for California over the next several decades will be a great challenge for water resource managers. Urban water needs are likely to grow while climate change, surface and groundwater pollution, infrastructure aging, and changing management priorities may decrease future supply and impact its reliability. Choosing an appropriate management response using standard methods will be extremely difficult and contentious as the scope and magnitude of these impacts are highly uncertain, and the large stakeholder community holds diverse views over desirable outcomes.; New analytic methods based on quantitative scenario analysis hold promise to improve decision support for long-term water resource planners. These methods can more explicitly address and accommodate the substantial uncertainty about the future and help identify management strategies that balance the objectives of numerous stakeholders. This dissertation presents two analyses to demonstrate the utility of such methods for long-term water resource planning.; This dissertation first documents the development and use of a model to generate quantitative scenarios of future water demand in California. The analysis reveals positive features of traditional scenario analysis and also highlights some of its major limitations. This work was used by the California Department of Water Resources in its California Water Plan Update 2005 as a first step toward a more comprehensive scenario approach for its long-term planning process.; The dissertation next describes a new analytic method for decision making under deep uncertainty called Robust Decision Making (RDM). To demonstrate how RDM can be a valuable analytic tool for California long-term water planning, the dissertation applies the methodology to a stylized representation of the water supply and demand management challenge facing Southern California. The analysis demonstrates that greater urban water use efficiency in conjunction with an appropriate level of new supply may be more robust to uncertain future water needs than new supply alone. Finally, the analysis suggests that adaptive strategies, coupled with urban efficiency, could significantly reduce the risk of constructing unnecessary infrastructure.