Hydroclimate Variability : Diagnosis Prediction and Application Balaji Rajagopalan Department of Civil, Encironmental and Architectural Engineering And Co-operative Institute for Research in Environmental Sciences (CIRES) University of Colorado Boulder, CO Fall 2003
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Hydroclimate Variability : Diagnosis Prediction and Application
Balaji Rajagopalan Department of Civil, Encironmental and Architectural Engineering And Co-operative Institute for Research in Environmental Sciences (CIRES) University of Colorado Boulder, CO Fall 2003. Hydroclimate Variability : Diagnosis Prediction and Application. Inter-decadal. - PowerPoint PPT Presentation
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Hydroclimate Variability : Diagnosis Prediction and Application
Balaji Rajagopalan
Department of Civil, Encironmental and Architectural Engineering
And
Co-operative Institute for Research in Environmental Sciences (CIRES)
University of Colorado
Boulder, CO
Fall 2003
A Water Resources Management Perspective
Time
Horizon
Inter-decadal
Hours Weather
ClimateDecision Analysis: Risk + Values
Data: Historical, Paleo, Scale, Models
• Facility Planning
– Reservoir, Treatment Plant Size
• Policy + Regulatory Framework
– Flood Frequency, Water Rights, 7Q10 flow
• Operational Analysis
– Reservoir Operation, Flood/Drought Preparation
• Emergency Management
– Flood Warning, Drought Response
Climate Variability
• Daily
• Annual
• Inter-annual to Inter-decadal
• Centennial
• Millenial
• Diurnal cycle• Seasonal cycle
• Ocean-atmosphere coupled modes (ENSO, NAO, PDO)
• Thermohaline circulation• Milankovich cycle
(earth’s orbital and precision)
American River at Fair Oaks - Ann. Max. Flood
020,00040,00060,00080,000
100,000120,000140,000160,000180,000
1900 1920 1940 1960 1980 2000
Year
An
n M
ax
Flo
w
100 yr flood estimated from 21 & 51 yr moving windows
What Drives Year to Year Variability in regional
Hydrology?(Floods, Droughts etc.)
Hydroclimate Predictions – Scenario Generation(Nonlinear Time Series Tools, Watershed Modeling)
Decision Support System(Evaluate decision strategiesUnder uncertainty)
Modeling Framework
Forecast
Diagnosis
Application
Research Activities
• Long Term Salinity Modeling on the Colorado River Basin
(USBR, CADSWES)
• Spring Streamflow forecasts on the Truckee / Carson Basin – Applications to Water Management
(USBR Truckee Office, CADSWES)
• Interdecadal Variability of Thailand and Indian Summer Monsoon
• Seasonal Cycle Shifts in Western US Hydroclimatology and Flood Forecasting(NSF, NOAA/WWA)
Research Activities..
• Tools for short term and long term streamflow forecasting and water management Decision Support System
(CIRES/Western Water Assessment, NOAA, USGS)
• Infrastructure Reliability Estimation under Hurricane Hazards
(NSF, Profs. Corotis and Frangopol)
Collaborators
• Edith Zagona, Terry Fulp - CADSWES• Martyn Clark, Subhrendu Gangopadhyay - CIRES • NOAA - Western Water Assessment (WWA)• Katrina Grantz, James Prairie, David Neumann,
Satish Regonda, Yeonsang Hwang, Nkrintra Singhrattna, Somkiat, Apipattanavis, Adam Hobson
Courses• CVEN 3323 (Fall) HydraulicEngineering
Pipe Network Design, Pumps, Open Channel flowHydrology
• Fall Climate forecast captures whether season will be above or below average
• Results comparable to winter forecast w/o climate
Wet Years Dry Years
1987 1988 1989
1987 1988 1989
1990 1991 1992
1990 1991 1992
1994 1995 1996
1994 1995 1996
1997 1998 1999
1997 1998 1999
Simple Water Balance
• St-1 is the storage at time ‘t-1’, It is the inflow at time ‘t’
and Rt is the release at time ‘t’.• Method to test the utility of the model• Pass Ensemble forecasts (scenarios) for It • Gives water managers a quick look at how much storage
they will have available at the end of the season – to evluate decision strategies
For this demonstration,• Assume St-1=0, Rt= 1/2(avg. Inflowhistorical)
St = St-1 + It - Rt
Water Balance
1995 K-NN Ensemble
PDFHistorical
PDF
1995 Storage
Truckee-Carson RiverWare Model
Future Work
• Stochastic Model for Timing of the RunoffDisaggregate Spring flows to monthly flows.
• Statistical Physical ModelCouple PRMS with stochastic weather generator (conditioned on climate info.)
• Test the utility of these approaches to water management using the USBR operations model in RiverWare
Jaguaribe 80% irrigation20% municipalMainly in AugTo November
Metropolitan80% Municipal20% IrrigationUniform distributionOver the year
Oros Reservoir
Seasonality of Oros Inflow
0
50
100
150
200
250
300
350
400
1 2 3 4 5 6 7 8 9 10 11 12
Month
Flo
w (
m^
3/s
)
Mean
Median
Quantile (75)
Quantile (25)
Quantile (90)
Quantile (10)
Seasonality of rain determined by N-S migration of the ITCZ
Rain Start: ITCZ reaches Southernmost (Feb) + January Cold Fronts
Rain End: ITCZ migrates N of Equator (June-July)
Predictors for Ceara Rainfall/Flow
Factors that Affect the ITCZ dynamics– State of Tropical Pacific: El Nino– State of the tropical Atlantic
0
10
20
30
40
50
60
70
80
90
1993 1994 1995 1996 1997 1998 1999 2000
Per90%
Per75%
Per50%
Per25%
Per10%
Obs
Marginal 90%
Marginal 75%
Marginal 50%
Marginal 25%
Marginal 10%
Oros Annual Flow Forecast from previous July
– model fit 1914-1991, k=30 Correlation (Median==Obs)=0.91
Seasonal Cycle Shifts in Annual Cycle of Streamflows
Key Points• Low Frequency Climate Variability (LFV) on interannual to
centenial time scales is a significant part of “natural” variability in the climate system.– A few large-scale climate forcings (“modes”) contribute to MOST of the LFV– ENSO, NAO, PDO– The forcings have large-scale spatial structure and modulate regional climate
• These forcings manifest into LFV in regional hydroclimate variables– Droughts– Floods (mean flows, maximum flows, flood frequency)– Seasonal Temperature and Precipitation and their spells– Storm days
• Implications for – Regional Flood-frequency analyses– Resources planning/management– Hazard management/response strategies– Hydroclimate modeling of watersheds and river basins
Research Directions• Drought Severity
– Longer Records/Tree Rings for diagnosis
– Time Scale for Forecasting? Statistical Properties of Drought ?
• Operational Analyses– Seasonal Supply & Demand
• P, T, Q => Attributes to Forecast ?
• Role of Groundwater ?
• Seasonal Low Flow Attributes
• Low Frequency variations in flood probabilities – Nonstationarity => Risk analysis, Regionalization
– Seasonal Forecast Possibility => Disaster insurance and planning
• Theoretical and Conceptual Models – Predictability => Concepts and Assessment
– Framework: Dynamics of Variability & Mechanisms <= Role of Numerical, Conceptual and Stochastic Models