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Impact of Climate Change on Flow in the Upper Mississippi River Basin

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Presentation on theme: "Impact of Climate Change on Flow in the Upper Mississippi River Basin"— Presentation transcript:

1 Impact of Climate Change on Flow in the Upper Mississippi River Basin
Eugene S. Takle Iowa State University Ames, IA USA Project collaborators: Manoj Jha, Zaitao Pan, Roy Gu Regional-Scale Climate Modelling Workshop World Climate Research Programme Lund, Sweden, 29 March - 1 April 2004

2 If we have perfect predictability of global fields, how well can we downscale this predictability to stream flow at one point?

3 Outline Domain and hydrological model (SWAT)
Calibration and validation Observations -> stream flow NNR -> RCM -> SWAT-> stream flow GCM -> RCM -> SWAT-> stream flow GHG -> GCM -> RCM -> SWAT -> stream flow Stream flow vs. precipitation Use for policy development For details see: Jha, M., Z. Pan, E. S. Takle, and R. Gu, 2003: Impacts of climate change on stream flow in the Upper Mississippi River Basin: A regional climate model perspective. Journal of Geophysical Research (in press).

4 Sub-Basins of the Upper Mississippi River Basin 119 sub-basins
Outflow measured at Grafton, IL Approximately one observing station per sub-basin model grid point

5 Soil Water Assessment Tool (SWAT)
Long-term, continuous watershed simulation model (Arnold et al,1998) Daily time steps Assesses impacts of climate and management on yields of water, sediment, and agricultural chemicals Physically based, including hydrology, soil temperature, plant growth, nutrients, pesticides and land management

6 SWAT Output with Various Sources
of Climate Input

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

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

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

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

11 RegCM2 Simulation Domain
Red = global model grid point Green/blue = regional model grid points

12 Annual Stream Flow Simulated by SWAT
Driven by the RegCM2 Regional Climate Model with NNR Lateral Boundary Conditions

13 Seasonal Stream Flow Simulated by SWAT
Driven by the RegCM2 Regional Climate Model with NNR Lateral Boundary Conditions

14 Mean Monthly Precipitation Simulated by
the RegCM2 Regional Climate Model with NNR Lateral Boundary Conditions

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19 Hydrological component comparison
between RegCM2 and SWAT RegCM2 SWAT Evapotranspiration 588 528 Surface runoff 151 166 Snowmelt 256 240 Note: All values are in mm per year averaged for in NNR run.

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22 Ten-Year Mean Monthly Stream Flow Generated by the
RegCM2 Regional Climate Model Driven with HadCM2 Global Model Results for the Contemporary and Future Scenario (2040s) Climate

23 Ten-Year Mean Precipitation Generated by the RegCM2
Regional Climate Model Driven with HadCM2 Global Model Results for the Contemporary and Future Scenario (2040s) Climate

24 Errors in Simulated Stream Flow
and Climate Change Comparisons Evaluate SWAT 1 vs. Measured SWAT error SWAT 2 vs. SWAT 1 RCM error SWAT 3 vs. SWAT 2 GCM error SWAT 3 vs. SWAT 1 GCM-RCM error SWAT 2 vs. Measured RCM-SWAT error SWAT 3 vs. Measured GCM-RCM-SWAT error SWAT 4 vs. SWAT 3 Climate change

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

26 Hydrologic Budget Components
Simulated by SWAT under Different Climates Hydrologic budget components Calibration ( ) Validation ( ) NNR CTL (around 1990s) SNR (around 2040s) % Change (SNR-CTL) Precipitation 856 846 831 898 1082 21 Snowfall 169 103 237 249 294 18 Snowmelt 168 99 230 245 291 19 Surface runoff 151 128 178 268 51 GW recharge 154 160 134 179 255 43 Total water yield 273 257 253 321 481 50 Potential ET 947 977 799 787 778 -1 Actual ET 547 541 528 539 566 5 All units are mm Yield is sum of surface runoff, lateral flow, and groundwater flow

27 Relation of Runoff to Precipitation
for Various Climates

28 Stream Flow vs. Precipitation
Regression Analysis: Stream Flow vs. Precipitation

29 Summary RCM provides meteorological detail needed by SWAT to resolve sub-basin variability of importance to streamflow There is strong suggestion that climate change introduces changes of magnitudes larger than variation introduced by the modeling process Relationship of streamflow to precipitation might change in future scenario climates

30 Future Directions Couple GCM, RCM, SWAT, Crop Model and Economic Model
Evaluate policy alternatives: Impact of introducing conservation practices Impact of introducing incentives Hypothesis: It is possible to balance profitability with sustainability in an intensively managed agricultural area under changing climate through development of robust policy

31 Evaluate Sustainability
GCM OBS RCM Crop Model NNR Climate Over UMRB Crop Yield SWAT Economic Model Soil Drainage Land-use Management Choices OBS Incentives Stream flow Soil Carbon Crop Production Water Quality Public Policy Evaluate Sustainability and Profitability

32 Evaluate Sustainability
GCM OBS RCM Crop Model NNR Climate Over UMRB Crop Yield SWAT Economic Model Soil Drainage Land-use Management Choices OBS Incentives Stream flow Soil Carbon Crop Production Water Quality Public Policy Evaluate Sustainability and Profitability

33 Without sufficient resolution, it just doesn’t look right.
EST&LM


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