Use of Intra-Seasonal and Seasonal Forecasts to Reduce ... · Weekly, out to 4 weeks •Estimate of...
Transcript of Use of Intra-Seasonal and Seasonal Forecasts to Reduce ... · Weekly, out to 4 weeks •Estimate of...
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Agricultural and Biological EngineeringAgricultural and Biological Engineering
Use of Intra‐Seasonal and Seasonal Forecasts to Reduce Risk in Regional Public Water Supply Management
Chris Martinez
University of Florida
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Agricultural and Biological Engineering
Overview
• Project Partners
• Project Background & Goals
• Methods
• Results
• Lessons Learned
• Relevance
Funded by NOAA’s Climate Program Office SARP-Water program
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Agricultural and Biological Engineering
Background
• Current sources:• Groundwater (13 wellfields)• Tampa Bypass Canal/Hillsborough River• Alafia River• C.W. Bill Young off‐stream reservoir• Desalination Plant
1998
2008
2012
Percentage of Water by Source
100%
61%
11%
28%
45.5%45.5%
9%
Groundwater Permit192 MGD
158 MGD
121 MGD
90 MGD
Pre‐1998
1998
2002
2008
(12-monthmoving average)
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Agricultural and Biological Engineering
Source Allocation Decisions
• Multiple decision scales:• Water year plan (6‐months prior)• Month to month adjustments• Operational decisions (weekly)
• Multiple constraints:• Permitted groundwater (12‐month moving average)• Minimum streamflows• Streamflow extraction ratio (maintain Fluoride limit)• Costs of different sources
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Agricultural and Biological Engineering
Project Goals
• Integrate forecast information into decision making– Multiple temporal scales– Relevant spatial scales– Integrate forecasts into suite of models used by Tampa Bay Water
• System‐wide Decision Support– What is the system‐wide benefit/risk of adopting forecast information?
– What is the reliability of the current system?– Value judgments under different scenarios?
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Agricultural and Biological Engineering
Links Between Climate/Hydrologic Information and Decisions by Tampa Bay Water
DecisionRequired Information
Climate/Hydrology
Set Prices and monthly Source Allocation for water-year
Update water-year Allocations
Time-Scale
18 monthsin advance
Monthly, out to 12 months
Operational Allocations
Weekly, out to 4 weeks
•Estimate of initial reservoir volume•Scenarios of historical conditions•Demand forecasts
•Precipitation and Streamflow forecasts
•Precipitation, Streamflow and Demand forecasts
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Agricultural and Biological Engineering
“Typical” Water Year
• Estimate of end of year reservoir level needed for plan for next water year
Oct --- Nov --- Dec --- Jan --- Feb --- Mar --- Apr --- May --- Jun --- Jul --- Aug --- Sep
ReservoirMax
Using Reservoir
Filling Reservoir
ReservoirMin
Max Groundwater
use Max DirectSurface Water
use
• Greater than expected groundwater pumping impacts next water year plan
• Seasonal forecasts can be used to determine expected higher/lower groundwater pumping in winter months
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Agricultural and Biological Engineering
Different Products for Different Time‐Scales
• Operational – Ensemble Precipitation, Streamflow and Demand forecasts derived from medium‐range forecast products
• Monthly/Seasonal – Probabilistic Precipitation and Streamflow/Withdrawal Climate‐based Forecasts
• Water‐Year – Decision Support, taking into account previous and next 12 months
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Agricultural and Biological Engineering
Operational Time‐scale
CurrentForecast
Historical Forecast Analogs
Historical Observations(Stations or NARR)
• Forecast analogs using the ESRL/PSD GFS Retrospective forecast archive • 1‐15 day
• 2.5° x 2.5°• 1979‐present
• Analog selection can be tailored to need
Ensemble ofHydrologic Forecasts
• +/‐ 30 day search window
• 100 analog forecasts
http://www.esrl.noaa.gov/psd/forecasts/reforecast/
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Agricultural and Biological Engineering
Precipitation Forecast Skill
F(x)
x
[ ] dx(x)FF(x)CRPS2
o∫∞
∞−
−=
CRPSS: Continuous Ranked Probability Skill Score
Ref
Forecast
CRPSCRPS1CRPSS −=
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Agricultural and Biological Engineering
Monthly/Seasonal Time‐scale
• Forecast analogs using CFS retrospective forecast archive http://cfs.ncep.noaa.gov/– Week 2
– Monthly
– Seasonal
• Climate‐based probability of exceedance streamflow forecasts
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Agricultural and Biological Engineering
Probability of Exceedance Streamflow Forecasts
Posterior probability of streamflow conditioned on predictor Streamflow Forecast
Stream
flow
Exceedance Probability (%)
Season
Lagged
Niñ03
.4
Correlation of Streamflow w/ ENSO
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Agricultural and Biological Engineering
Decision Support + Scenarios
• Inputs:– Forecasted Demand
– Forecasted Withdrawal
• Outputs:– Optimized source‐water allocations based on preferences/constraints
– End of year reservoir volume
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Agricultural and Biological Engineering
Lessons Learned
• There is a learning curve associated with using weather/climate datasets!!! (for hydrologists/engineers, at least…)
• Limited number of forecasted variables archived in retrospective archives may limit usefulness
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Agricultural and Biological Engineering
Relevance
• Tools/approaches that can easily be replicated in other regions– Analog forecasts
– Exceedance streamflow forecasts