Using Weather Forecasts to Better Leverage Our Water
Resources InfrastructureRob Hartman
RKH Consulting Services
Representing Scripps Institution of OceanographyOrange County Water Summit, June 2018
Here’s the Problem…
• Growing population and demands on water supply• Our climate is quite variable (unreliable)• New water storage (reservoirs) is very limited
• Physical locations (good sites w/excess water)• Very expensive (planning, construction, legal)• Environmental concerns• Very slow (10+ years)
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• CA has the largest year to year precipitation variability in the US.
• The year to year variability in CA is largely caused by the wettest days (ARs).
• Major challenge for water management
Coefficient of variation (std.dev/mean) for annual precipitation 1950-2008Dettinger, M.D., Ralph, F.M., Das, T., Neiman, P.J., and Cayan,
D., 2011: Atmospheric rivers, floods, and the water resources of California. Water, 3, 455-478.
Variability of Annual Precipitation
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So what can we do?
Get MORE out of our existing water resources infrastructure!
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Weather Forecasts Are Improving
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Atmospheric Rivers are like rivers in the sky –Rivers of water vapor
Dettinger and IngramScientific American2013
From Ralph et al. 2011, Mon. Wea. Rev.
These color images represent satellite observations of atmospheric water vapor over the oceans.
Warm colors = moist airCool colors = dry air
ARs can be detected with these data due to their distinctive spatial pattern.
In the top panel, the AR hit central California and produced 18 inches of rain in 24 hours.
In the bottom panel, the AR hit the Pacific Northwest and stalled, creating over 25 inches of rain in 3 days.
One AR transports as much water as 25 Mississippi Rivers,
but as vapor rather than liquid(from Ralph et al. 2017)
Dettinger and Cayan Drought and the Delta—A Matter of Extremes San Francisco Estuary and Watershed Science, April 2014
Total precipitation
LARGE STORM CONTRIBUTION
All Other Days
• 85% of interannual variability results from how wet the 5% wettest days are each year.• These days are mostly atmospheric river events.
WHETHER A YEAR WILL BE WET OR DRY IN CALIFORNIA IS MOSTLY DETERMINED BY THE NUMBER AND STRENGTH OF ATMOSPHERIC RIVERS STRIKING THE STATE.
AR Forecast Challenges and Research
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Timing DurationIntensityLocation
“With enough forecast lead time to allow for effective decisions”
Forecast InformedReservoir Operations (FIRO)
“Evaluating and demonstrating improved reservoir outcomes by leveraging weather/water forecasts and
research in operational decisions to release or retain water”
• Lake Mendocino (Russian River) 2014 -• Prado Dam (Santa Ana River) 2017 -
• Plans for expansion and transfer 2018 -
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Lake Mendocino FIRO - Goals
Improved water supply reliabilityUndiminished or improved flood control capacity
Improved environmental outcomes
Explore improvements in multi-purpose reservoir management outcomes through leveraging state-of-the-
science technology in monitoring, modeling, and forecasting and through targeted research and development
All without pouring a single yard of concrete…
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Lake Mendocino FIRO
Lake Mendocino • 122,000 AF Reservoir• Upper Russian River• Owned by USACE• Operated for flood control by
South Pacific Division• Operated for water supply by
Sonoma County Water Agency (SCWA)
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Lake Mendocino FIROSeasonal Water Storage
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Lake Mendocino FIROPreliminary Viability Assessment - 2017
SCWA – Development and evaluation of a reservoir model that leverages streamflow forecast skillHEC – Evaluation of multiple reservoir management rule-sets/schemes in the HEC-WAT framework
CW3E – AR analysis, monitoring enhancements, and quantified forecast skill requirements
http://scholarship.org/uc/item/66m803p2
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Lake Mendocino FIROEnd of Year Reservoir Storage
Substantial gains in water storage over existing WCM operations by leveraging information in streamflow forecasts
Lake Mendocino FIRO“Moving the Needle”
• Improved monitoring• Ground based• Remote sensing• Airborne
• AR science investigations• WestWRF• AR Recon / Data Assimilation• Subseasonal to seasonal
• Engineering technologies• Models• Decision support
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NOAA G-IV
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Applying FIRO to Prado Dam
Prado Dam – Flood Control and Water Conservation
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Year Flood Season
Non-Flood Season
1969 revision to reservoir regulation schedule
490 ft
1990 update to water control manual
494 ft
1993 MOA 494 ft 505 ft2006 MOA 498 ft 505 ft
Santa Ana River Groundwater Recharge below Prado Dam
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Prado Basin Resources
• OCWD owns 2,150 acres behind Prado Dam
• Endangered species habitat throughout Prado Basin (riparian habitat)
• OCWD implements programs to enhance native riparian habitat and control non-native cowbird population
• 800 acres of mitigation areas
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Water Resources & Natural Resources Management: hand-in-hand
• Established Santa Ana Watershed Association• Funding to improve Santa Ana River
environment• Removing non-native Arundo donax
• Creating 18,000 afy of new water• Santa Ana Sucker fish recovery efforts• Recovered least Bell’s vireo
• From 10 to > 500 territories in Prado Basin• 1,700 territories in SA Watershed
Least Bell’s Vireo Territories
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1983 2016
Efforts to Increase Stormwater Capture at Prado
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• Seeking stormwater capture to elevation 505 feet in flood season
• Permanent change to 505 feet year-round being evaluated in Prado Basin Feasibility Study being conducted by Corps with OCWD as local sponsor
• Temporary deviation to 505 feet approved this flood season
Prado Forecast-Informed Reservoir Operations (FIRO)
• Using enhanced weather forecasting and runoff estimation tools to inform future reservoir operations
• Includes growing understanding of Atmospheric River (AR) storms
• Leveraging efforts and experience gained through Lake Mendocino project
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Prado FIRO Phase I(began Fall 2017)
• Task 1: Prado FIRO Steering Committee• Form steering committee • Conduct quarterly meetings • Create technical support team
• Task 2: Creation of FIRO Viability Assessment Workplan• Define FIRO Workplan and desired outcomes• Develop Workplan elements customized to Prado
• Identify necessary technical studies to be done in Phase II
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Thank You
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