System Stability in Model Complexity for Integrated Water Management in California

Abstract

This paper presents an application of Reynolds transport theorem (RTT) to California Central Valley water resources system and projects and its utility for integrated water resources management (IWRM). Using long-term historical and estimated natural outflows of the Sacramento and San Joaquin Valleys, it defines Basin Stress Index and uses it to characterize historical beneficial water uses in the two valleys. It then gives an overview of evolutionary water resources utilization policies in California for multiple competing and complementary beneficial uses and how these policies are brought progressively to the modeling environment in support of planning and operating the Central Valley water resources and projects. This paper highlights the resulting modeling complexity and presents insights about the stability of the system due to unique natural characteristics of the Central Valley. The application of RTT to this water resources system is shown by development of regional water balance formulations and statistics that depict how their components influence the stability of model results. The author posits that the development of such bounded water balance formulations will help advance IWRM. The paper also illustrates the complementary nature of system stability and application of theory to a complex problem to provide useful insights for informed decision making and saving model development costs. Finally, the paper suggests that the analysis technique applied to the Central Valley water resources system and world-class water projects may be useful for a pedagogical development for the emergent concept of IWRM for sustainable water resource use.