Enhancing California Water Resource Decision Support System
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: California is a leader among states in its response to warnings about global warming. In 2005, the governor, supported by the State Legislature, issued an Executive Order that set greenhouse gas emissions targets and established a California Action Team (CAT) responsible for biennial reports on climate change’s potential effects on various areas including water resources. To support decision-making, under the guidance of the CAT, California Department of Water Resources and Bureau of Reclamation are using IPCC climate change scenarios and a newly-developed water management model (Calsim-II) to predict potential critical issues for water management. This proposal aims to assist the state government’s efforts to make water management more effective. Our proposal focuses on research areas that would strengthen the Calsim system’s capabilities in providing decision support for water resource management. We propose to improve the Calsim system with uncertainty reduction and risk assessments by refining it from its current deterministic mode to a probabilistic mode. The improved system will then be used to project the potential extremes for California water resources as result of climate change. Projection with uncertainty analysis and risk assessment is necessary for the state to develop the mitigation strategy on potential water crisis. The methods employed to achieve the proposal’s scientific goal are: (1) Develop a hybrid dynamical and statistical downscaling technology. This method will make the initial downscaling estimates using an RCM nested inside a GCM, then adjust the estimate errors using spatially-distributed error models derived from California’s long-term observational data. (2) Use a variety of satellite remotely-sensed data in conjunction with California’s abundant ground measurements. A special study is proposed to investigate a more accurate estimation of snow water equivalent (SWE), the source of most of California’s fresh water. (3) Provide uncertainty analysis and risk assessment for Calsim’s water management solutions. We propose to examine a model’s errors on key variables by making retrospective runs for many decades and use California’s long-term observation data to statistically quantify the model’s uncertainty distributions under different circumstances. The uncertainty distributions are assumed to be the model’s inherent behaviors and are invariant in the model predictions. In this way, the Calsim input will be an ensemble of input members randomly generated according to the uncertainty’s statistical characteristics. Consequently, the Calsim solution will be probabilistic and will provide quantitative risk assessments. (4) Study California’s critical water resource issues under the IPCC climate change scenarios. We will conduct numerical study using the improved system to explore ensemble predictions of 20th and 21st century climate from multiple IPCC scenarios. The results will be differentiated to identify the impact of climate change on water resource managements and decision-making. The proposed research will provide strong support for multiple facets of the state’s ongoing management responses to climate change.