SY015-0001
Assessing the Viability of Forecast-Informed Reservoir Operations (FIRO) in Western U.S. Reservoirs Where Atmospheric Rivers Are Key to Both Water Supply and Flooding: Summary, Lessons Learned, and Broader Implications
Tuesday, 8 December 2020
Poster
F Martin Ralph, Scripps Institution of Oceanography, UC San Diego, Center for Western Weather and Water Extremes, La Jolla, CA, United States, Jay Jasperse, Sonoma Water, Santa Rosa, CA, United States, Cary Talbot, US Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS, United States, Joseph Forbis, US Army Corps of Engineers, Sacramento, CA, United States, Greg Woodside, Orange County Water District, Fountain Valley, CA, United States, John Leahigh, California Department of Water Resources, Sacramento, United States, Curt Aikens, Yuba Water Agency, Marysville, CA, United States, Arleen ODonnell, Eastern Research Group, Inc, Lexington, United States and Robert Hartman, Robert Hartman Consulting, Folsom, CA, United States
Abstract:
Are modern weather forecasts accurate enough to enable safe use in reservoir operations where the stakes are high? Many reservoirs are operated for multiple, and sometimes conflicting purposes of providing both water supply and flood control, all while considering environmental needs. Although some (largely private) reservoirs have used weather forecasts in their operations, the majority are operated using rules established when forecasts had very low skill and thus were not included as allowable formal inputs into daily operations. However, with advances in weather prediction skill over the decades since the dams were built, or their rule curves updated, it is possible that forecasts today are skillful enough to enable their use. Forecast-Informed Reservoir Operations (FIRO) is a program to test this possibility along the US West Coast where the needs are great and where predictive skill has emerged for the dominant storm type – atmospheric rivers (AR).
In 2014 a cross-disciplinary, multi-agency steering committee formed to develop and execute a workplan to evaluate FIRO viability. This study, originally envisioned as a purely paper/table-top assessment, showed such positive early results in terms of AR prediction skill that a deviation request to test the ideas though real-world reservoir operations was submitted to USACE in 2018. After formal review, USACE approved the plan.
By mid-2020, Lake Mendocino has been operated successfully for two winters under a deviation. It has stored significantly more water than it would have absent the deviation and has thus substantially mitigated water supply concerns during its 3rd driest winter on record. An update to the water control manual is underway to operationalize FIRO and create an adaptive approach to use future improvements in forecast skill to further increase the flexibility to release water before or retain water after a major storm based on AR forecasts. Similar assessments are now underway at three additional sites chosen to represent a wide range of rural, urban, coastal, inland, snow-impacted, and rain-dominated locations.
This presentation summarizes the partnership between research and operations that is at FIRO’s core, methods used to advance the skill of predicting ARs, the current status of 4 viability assessments underway, and future directions.
