1 water supply forecasting research at unlv thomas piechota, phd, p.e. director of sustainability...
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Water Supply Forecasting Research at UNLV
Thomas Piechota, PhD, P.E.Director of Sustainability and Multidisciplinary Research
Associate Professor, Department of Civil and Environmental Engineering
Kenneth Lamb, P.E.
Funded By: NOAA
Outline
Climate Variability and the Colorado River BasinExisting Research BasisCurrent Research GoalEstablishing Long Lead Climate/Streamflow
teleconnectionsDevelop Weighted Forecasting Method
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Climate Variability
Linkages of Colorado River basin hydrology with: Interannual climate variability (2-7 years)
El Niño - Southern Oscillation (ENSO)Northern Atlantic Oscillation (NAO)Pacific Ocean Sea Surface Temperatures (SSTs)
Interdecadal climate variability (10-20 years)Atlantic Multidecadal Oscillation (AMO)Pacific Decadal Oscillation (PDO)
Motivation: Improved long range(6-24 months in advance) streamflow forecasting 3
Climate Indices - Streamflow
Timilsena, Piechota, Tootle, & Singh, 2009
Pacific Ocean SST - Streamflow
Tootle & Piechota, 2005
Pacific Ocean SST - Snowpack
Aziz, Tootle, Piechota, Gray, 2009
(+)(-)
(-)
(-)(+)
Research Project Goal
Improve the “Out-Year” inputs used by USBRIdentify long-lead climate-streamflow connectionsDevelop weighted forecast approach
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ESPOUTLOOKESP
3-MONTH
APR-JUL COORDINATED
USBR INTERPOLATION
1976-2005 AVERAGE
Research Project Goal
Improve the “Out-Year” inputs used by USBRIdentify long-lead climate-streamflow connectionsDevelop weighted forecast approach
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Analysis
Lagged Rank Sum Testing SOI, PDO, NAO, AMOIndividually and ENSO-Coupled
Lagged Singular Value Decompostion (SVD)Pacific Ocean SSTs
Generate weighted forecasts and compare with:30-Year AverageESP Outlook
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Identify the Strongest Lag
Rank Sum Test Results
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Developing SST Teleconnection
Singular Value Decompostition (SVD) - Identifies covariance between two datasets
Pacific Ocean Sea Surface Temperature Data
(1951 – 2003)
CRB Naturalized/Unimpaired Streamflow Data
(1952 – 2004)
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3-Month SST Avg SVD Results
Why This Region?
Yang et al. 2002:Change in SST is evidence of a strong/weak
wintertime jet stream
Why the 1-year lag? Anybody want a Masters degree? 14
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Forecasting With SST Index
Forecast created using a weighted resampling of the observed data (1976-2005)Four Different Weighting Formulas
3-Month Avg. SST intervals: DJF, JFM, FMAPredictands: April-July Volume, Yearly Volume
0 5 10 15 20 25 30 350.000.100.200.300.400.500.600.700.800.901.00
W1 W2 W3 W4
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Assessing Forecast Skill
Linear Error in Probability Space (LEPS) scoreCompares forecast to the observed mean
Probability of Observed values compared with probability of Forecasted values:
2 23(1 | | ) 1f o f f o vLEPS P P P P P P
Qf
QO
Pf
PO
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Skill Results (DJF | Lag 1 year)
30-yr average skill scores at each location
(PRELIMINARY)
Conclusions
Improvement to the 30-Year Avg using HondoRemaining Work:
Quantify Improvement to the ESP Outlook
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