Streamflow impacts of biofuel policy-driven landscape change

Area of Science:

• Climate Science
• Hydrology
• Agricultural Science

Background:

• Policy-driven expansion of bioenergy crops can alter land surface characteristics.
• Changes in land use impact regional climate and water resources.

Purpose of the Study:

• To evaluate the effects of biofuel crop expansion on precipitation (P), potential evapotranspiration (PET), and streamflow in the U.S.
• To assess the potential for increased water stress in the High Plains due to biofuel production.

Main Methods:

• Regional climate simulations using the Weather Research Forecast (WRF) model coupled with the NOAH land surface model.
• Evaluation of current and biofuel cropping system scenarios using atmospheric forcing data from 1979-2004.

Main Results:

• Projected increase in mean annual PET under the biofuel scenario, exceeding inter-annual variability.
• Estimated changes in mean streamflow volume range from -56% to +20% across the conterminous U.S.
• Significant streamflow reduction (average 20%) in Kansas and Oklahoma primarily driven by increased PET.

Conclusions:

• Increased PET due to biofuel feedstock production is the dominant factor driving streamflow changes.
• Biofuel crop expansion is likely to exacerbate water stress in the High Plains.
• Sustainable biofuel policies must account for the water scarcity implications of feedstock production.