Tools For Drought Management
• Water Management in the face of droughts
require• Skilful Hydrologic Forecasting/Simulation Tool
» Statistical or Hydrologic Models (PRMS, SWAT, etc.)
for ~seasonal time scales» Stochastic Flow Simulation tools for longer term
(multi-year, decades) planning and management
• Decision Support tool of the agriculture/water resources system
» RiverWare
Seasonal Streamflow Forecast/Simulation
• Hydrologic Models– PRMS, SWAT
• Statistical Models– Nonlinear Regression approach for ensemble
forecasts [incorporating large-scale land-ocean-atmospheric information, Grantz et al., 2005; Regonda et al., 2006]
– Skilful, provides uncertainty estimates via ensembles
Truckee / Carson Basin - Application
• Study Area– Hydroclimatology, Management
• Spring Streamflow Forecast Models[incorporating large-scale land-ocean-atmospheric information, Grantz et al., 2005]
• Decision Support Model• Drive the streamflow forecast through the
decision model. Investigate skills in the decision variables
INDEPENDENCE
DONNERMARTIS
STAMPEDE
BOCA
PROSSER
TRUCKEERIVER
CARSONRIVER
CARSONLAKE
Truckee
CarsonCity
Tahoe City
Nixon
Fernley
DerbyDam
Fallon
WINNEMUCCALAKE (dry)
LAHONTAN
PYRAMID LAKE
NewlandsProject
Stillwater NWR
Reno/Sparks
NE
VA
DA
CA
LIF
OR
NIA
LAKE TAHOE
Study Area
TRUCKEE CANAL
Farad
Ft Churchill
NEVADA
CALIFORNIA
Carson
Truckee
Average Monthly Flows
• Primarily snowmelt driven basins
(April, May, June)
• Correlate Fall/ Winter Climate Signals with AMJ Streamflow
Management Issues
• Irrigation/Agriculture decisions on the Newland Irrigation district are made in Feb much before the peak flow occurs
• So, skilful long-lead seasonal streamflow forecasts on Truckee and Carson Rivers are required
• Forecasts determine – How storage targets will be met
on the Lahonton reservoir forirrigation
– How much water to divertfrom Truckee to Carson viathe Truckee Canal
– How much water will beavailable for Irrigation
Truckee Canal
Decision Variables
• Lahontan Storage Available for Irrigation
• Truckee River Water Available for Fish
• Diversion through the Truckee Canal
RiverWare – River and Reservoir Decision Support System
Inflow Forecast
OR
Historical Hydrology
OR
Stochastic inflows
Models interaction of
Hydrologic response of River /Reservoir system (includes
Hydropower)
With
Multi-objective operating policies
Operational Decisions
Predictions
Statistical Output
Economic Analysis
Environ analysis
Tradeoff Analysis
Truckee-Carson RiverWare Model
Winter Climate Link
500 mb Geopotential Height
Carson Spring Flow
• High flow years go with S.Westerly winds in the Basin during winter increased moisture/snow increased streamflow in spring. • Vice-Versa for Low flow years Grantz et al., 2005 – Water Resources Research
High flow Years Low flow Years
• Identified large scale land-ocean-atmosphere predictors for Truckee/Carson spring (April-June total) streamflow
• Used a Nonlinear regression framework (local polynomials) to generate ensemble of spring streamflow forecasts
• Forecasts issued on the 1st of each month starting from Nov 1st through April 1st
• Skills evaluated using correlation coefficient and RPSS(RPSS = 1 implies categorical forecast, 0, no better than
climatology)
Forecasting ResultsTruckee RPSS results
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Nov 1st Dec 1st Jan 1st Feb 1st Mar 1st Apr 1st
Month
Med
ian
RP
SS
(al
l yea
rs)
GpH & SWE
SWE
Carson RPSS results
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Nov 1st Dec 1st Jan 1st Feb 1st Mar 1st Apr 1st
Month
Med
ian
RP
SS
(al
l yea
rs)
GpH & SWE
SWE
Truckee Forecasted vs. Observed Correlation Coeff
0
0.2
0.4
0.6
0.8
1
Nov 1st Dec 1st Jan 1st Feb 1st Mar 1st Apr 1st
Month
Co
rrel
atio
n C
oef
f
GpH & SWE
SWE
Carson Forecasted vs. Observed Correlation Coeff
0
0.2
0.4
0.6
0.8
1
Nov 1st Dec 1st Jan 1st Feb 1st Mar 1st Apr 1st
Month
Co
rrel
atio
n C
oef
f.
GpH & SWE
SWE
Truckee Likelihood Results
0
0.5
1
1.5
2
2.5
Nov 1st Dec 1st Jan 1st Feb 1st Mar 1st Apr 1st
Month
Med
ian
Lik
elih
oo
d (
all
year
s)
GpH & SWE
SWE
Carson Likelihood Results
0
0.5
1
1.5
2
2.5
Nov 1st Dec 1st Jan 1st Feb 1st Mar 1st Apr 1st
Month
Med
ian
Lik
elih
oo
d (
all
year
s)
GpH & SWE
SWE
•Skills increase with decrease in lead-time
•Significant skill even on Jan 1st and Feb 1st (when snow infois partial)
Forecast Ensembles are Used to drive the Decision Support
System for the Truckee/Carson Baisn
(Forecast skills of the decision variables evaluated)
Decision Model
Results0 100 300 500
010
030
050
0
Perfect Forecast Irrigation Water (kaf)
Med
ian
of E
nsem
ble
Irrig
atio
n W
ater
(kaf
)
r=0.17
0 50 100 150
050
100
150
Perfect Forecast Diversion (kaf)
Med
ian
of E
nsem
ble
Div
ersi
on(k
af)
r=0.23
0 200 400 600
020
040
060
0
Perfect Forecast Fish Water (kaf)
Med
ian
of E
nsem
ble
Fis
h W
ater
(kaf
)
r=0.36
0 100 200 300 400 500
010
020
030
040
050
0
Perfect Forecast Irrigation Water (kaf)
Med
ian
of E
nsem
ble
Irrig
atio
n W
ater
(kaf
)
r=0.54
0 50 100 150
050
100
150
Perfect Forecast Diversion (kaf)
Med
ian
of E
nsem
ble
Div
ersi
on(k
af)
r=0.38
0 200 400 600
020
040
060
0
Perfect Forecast Fish Water (kaf)
Med
ian
of E
nsem
ble
Fis
h W
ater
(kaf
)
r=0.62
0 100 200 300 400 500
010
030
050
0
Perfect Forecast Irrigation Water (kaf)
Med
ian
of E
nsem
ble
Irrig
atio
n W
ater
(kaf
)
r=0.79
0 50 100 150
050
100
150
Perfect Forecast Diversion (kaf)
Med
ian
of E
nsem
ble
Div
ersi
on(k
af)
r=0.78
0 200 400 600
020
040
060
0
Perfect Forecast Fish Water (kaf)
Med
ian
of E
nsem
ble
Fis
h W
ater
(kaf
)
r=0.93
Canal Diversion Water for FishIrrigation Water
Dec 1st Forecast
Feb 1st Forecast
Apr 1st Forecast
Significant skillEspecially from Feb1stonwards
Dry Year: 1994April 1st February 1st December 1st
Truckee ForecastTruckee Forecast
Carson ForecastCarson Forecast
Storage for IrrigationStorage for Irrigation
Canal DiversionCanal Diversion
Water for FishWater for Fish
Wet Year: 1993April 1st February 1st December 1st
Truckee ForecastTruckee Forecast
Carson ForecastCarson Forecast
Storage for IrrigationStorage for Irrigation
Canal DiversionCanal Diversion
Water for FishWater for Fish
Normal Year: 2003April 1st February 1st December 1st
Truckee ForecastTruckee Forecast
Carson ForecastCarson Forecast
Storage for IrrigationStorage for Irrigation
Canal DiversionCanal Diversion
Water for FishWater for Fish
Exceedance Probabilities 1994 (Dry Year) Apr 1st Feb 1st Dec 1st Historical
Irrigation Water mean value (kaf) 94 161 214 264264 kaf Irrigation Water exceedance probability 4% 14% 18% 50%Fish Flow mean value (kaf) 0 42 39 19960.5 kaf Fish Flow exceedance probability 0% 57% 58% 87%Canal Diversion mean value (kaf) 52 107 121 84
1993 (Wet Year) Apr 1st Feb 1st Dec 1st Historical
Irrigation Water mean value (kaf) 291 332 246 264264 kaf Irrigation Water exceedance probability 73% 73% 31% 50%Fish Flow mean value (kaf) 452 391 138 19960.5 kaf Fish Flow exceedance probability 100% 99% 81% 87%Canal Diversion mean value (kaf) 8 29 101 84
2003 (Normal Year) Apr 1st Feb 1st Dec 1st Historical
Irrigation Water mean value (kaf) 261 268 225 264264 kaf Irrigation Water exceedance probability 40% 49% 26% 50%Fish Flow mean value (kaf) 76 223 71 19960.5 kaf Fish Flow exceedance probability 61% 91% 69% 87%Canal Diversion mean value (kaf) 126 106 108 84
Summary• Developed a streamflow forecast framework incorporating large-
scale ocean-atmospheric-land variables• Skilful long-lead streamflow forecasts obtained on the
Truckee/Carson river basin ~4-5 months ahead of the spring peak flow
• Developed a Decision Support System that incorporates all the management aspects of the water resources system
• Skilful streamflow forecasts translated into skills in the decision variables – especially the amount of flow available for irrigation
• The Integrated streamflow-Decision Support System provides a robust framework for effective management of droughts both in theshort and longer time scales
• Streamflow scenarios can be generated conditioned on climate change, land use change, water use change etc. and management/decision strategies evaluated
AcknowledgementsMs. Katrina Grantz for
USBR Truckee Office for financial support of this study
CADSWES for computation and logistics support