Impact of Climate Change Impact of Climate Change on Flow in the Upper on Flow in the Upper

Mississippi River BasinMississippi River Basin

Eugene S. TakleEugene S. TakleIowa State UniversityIowa State University

Ames, IA 50011 USAAmes, IA 50011 USAgstakle@iastate.edugstakle@iastate.edu

Project collaborators:Project collaborators:

Manoj Jha, Zaitao Pan, Roy GuManoj Jha, Zaitao Pan, Roy Gu

9th Annual GHP meeting, GKSS, Geesthacht, Germany, Sept. 22-26, 2003

If we have perfect If we have perfect predictability of global predictability of global fields, how well can we fields, how well can we

downscale this downscale this predictability to stream predictability to stream

flow at one point?flow at one point?

OutlineOutline Domain and hydrological model (SWAT)Domain and hydrological model (SWAT) Calibration and validationCalibration and validation Observations -> stream flowObservations -> stream flow NNR -> RCM -> SWAT-> stream flowNNR -> RCM -> SWAT-> stream flow GCM -> RCM -> SWAT-> stream flowGCM -> RCM -> SWAT-> stream flow GHGGHG -> GCM -> RCM -> SWAT -> -> GCM -> RCM -> SWAT ->

stream flowstream flow Stream flow vs. precipitationStream flow vs. precipitation

For details see: Jha, M., Z. Pan, E. S. Takle, and R. Gu, 2003: Impacts of climate change on stream flow in the Upper MississippiRiver Basin: A regional climate model perspective. Accepted byJournal of Geophysical Research.

Sub-Basins of theSub-Basins of theUpper MississippiUpper MississippiRiver BasinRiver Basin

119 sub-basins

Outflow measuredat Grafton, IL

Approximately oneobserving stationper sub-basin

Approximately onemodel grid pointper sub-basin

Soil Water Assessment Soil Water Assessment Tool (SWAT)Tool (SWAT)

Long-term, continuous watershed Long-term, continuous watershed simulation model (Arnold et al,1998)simulation model (Arnold et al,1998)

Daily time stepsDaily time steps Assesses impacts of climate and Assesses impacts of climate and

management on yields of water, management on yields of water, sediment, and agricultural chemicalssediment, and agricultural chemicals

Physically based, including hydrology, Physically based, including hydrology, soil temperature, plant growth, soil temperature, plant growth, nutrients, pesticides and land nutrients, pesticides and land managementmanagement

SWAT Output with Various Sources SWAT Output with Various Sources of Climate Inputof Climate Input

Calibration of SWAT:Calibration of SWAT:Annual Stream Flow at Grafton, ILAnnual Stream Flow at Grafton, IL

Calibration of SWAT:Calibration of SWAT:Monthly Stream Flow at Grafton, ILMonthly Stream Flow at Grafton, IL

Validation of SWAT:Validation of SWAT:Annual Stream Flow at Grafton, ILAnnual Stream Flow at Grafton, IL

Validation of SWAT:Validation of SWAT:Monthly Stream Flow at Grafton, ILMonthly Stream Flow at Grafton, IL

RegCM2 Simulation DomainRegCM2 Simulation Domain

Red = global model grid point Green/blue = regional model grid points

Annual Stream Flow Simulated by SWATAnnual Stream Flow Simulated by SWATDriven by the RegCM2 Regional ClimateDriven by the RegCM2 Regional Climate

Model with NNR Lateral Boundary ConditionsModel with NNR Lateral Boundary Conditions

Seasonal Stream Flow Simulated by SWATSeasonal Stream Flow Simulated by SWATDriven by the RegCM2 Regional ClimateDriven by the RegCM2 Regional Climate

Model with NNR Lateral Boundary ConditionsModel with NNR Lateral Boundary Conditions

Mean Monthly Precipitation Simulated by Mean Monthly Precipitation Simulated by the RegCM2 Regional Climate Model the RegCM2 Regional Climate Model

with NNR Lateral Boundary Conditionswith NNR Lateral Boundary Conditions

Without sufficient resolution, it just doesn’t look right.

EST&LM

Ten-Year Mean Precipitation Generated by the RegCM2 Ten-Year Mean Precipitation Generated by the RegCM2 Regional Climate Model Driven with HadCM2 Regional Climate Model Driven with HadCM2

Global Model Results for the Contemporary and Global Model Results for the Contemporary and

Future Scenario (2040s) ClimateFuture Scenario (2040s) Climate

Ten-Year Mean Monthly Stream Flow Generated by the Ten-Year Mean Monthly Stream Flow Generated by the RegCM2 Regional Climate Model Driven RegCM2 Regional Climate Model Driven

with HadCM2 Global Model Results for the with HadCM2 Global Model Results for the Contemporary and Future Scenario (2040s) ClimateContemporary and Future Scenario (2040s) Climate

Errors in Simulated Stream FlowErrors in Simulated Stream Flow and Climate Changeand Climate Change

ComparisonsComparisons EvaluateEvaluate

SWAT 1 vs. MeasuredSWAT 1 vs. Measured SWAT errorSWAT error

SWAT 2 vs. SWAT 1SWAT 2 vs. SWAT 1 RCM errorRCM error

SWAT 3 vs. SWAT 2SWAT 3 vs. SWAT 2 GCM errorGCM error

SWAT 3 vs. SWAT 1SWAT 3 vs. SWAT 1 GCM-RCM errorGCM-RCM error

SWAT 2 vs. MeasuredSWAT 2 vs. Measured RCM-SWAT errorRCM-SWAT error

SWAT 3 vs. MeasuredSWAT 3 vs. Measured GCM-RCM-SWAT errorGCM-RCM-SWAT error

SWAT 4 vs. SWAT 3SWAT 4 vs. SWAT 3 Climate changeClimate change

Comparison of Simulated Stream Flow under Comparison of Simulated Stream Flow under Climate Change with Various Model BiasesClimate Change with Various Model Biases

Hydrologic Hydrologic budget budget

componentscomponents

CalibratioCalibrationn

(1989-(1989-1997)1997)

ValidatioValidationn

(1980-(1980-1988)1988)

NNRNNR

(1980-(1980-1988)1988)

CTLCTL

(aroun(around d

1990s)1990s)

SNRSNR

(aroun(around d

2040s)2040s)

% Change (SNR-% Change (SNR-CTL)CTL)

PrecipitationPrecipitation 856856 846846 831831 898898 10821082 2121

SnowfallSnowfall 169169 103103 237237 249249 294294 1818

SnowmeltSnowmelt 168168 9999 230230 245245 291291 1919

Surface runoffSurface runoff 151151 128128 151151 178178 268268 5151

GW rechargeGW recharge 154154 160160 134134 179179 255255 4343

Total water Total water yieldyield

273273 257257 253253 321321 481481 5050

Potential ETPotential ET 947947 977977 799799 787787 778778 -1-1

Actual ETActual ET 547547 541541 528528 539539 566566 55

Hydrologic Budget Components Hydrologic Budget Components

Simulated by SWAT under Different ClimatesSimulated by SWAT under Different Climates

All units are mmYield is sum of surface runoff, lateral flow, and groundwater flow

Relation of Runoff to Precipitation Relation of Runoff to Precipitation for Various Climatesfor Various Climates

Regression Analysis: Regression Analysis:

Stream Flow vs. PrecipitationStream Flow vs. Precipitation

Stream flow vs. precipitation Scenario Slope1. Measured stream flow vs. observed precipitation (1980-1997) Observed 0.662. Simulated stream flow vs. observed precipitation (1980-1988) SWAT 1 0.653. Simulated stream flow vs. RCM/NNR precipitation (1980-1988) SWAT 2 0.874. Simulated stream flow vs. CTL precipitation (around 1990s) SWAT 3 0.645. Simulated stream flow vs. SNR precipitation (around 2040s) SWAT 4 1.16