Khanal Sami, Anex Robert P, Anderson Christopher J, Herzmann Daryl E
School of Environment and Natural Resources, Ohio State University, Wooster, OH, United States of America.
Dept. of Biological Systems Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
PLoS One. 2014 Oct 7;9(10):e109129. doi: 10.1371/journal.pone.0109129. eCollection 2014.
Likely changes in precipitation (P) and potential evapotranspiration (PET) resulting from policy-driven expansion of bioenergy crops in the United States are shown to create significant changes in streamflow volumes and increase water stress in the High Plains. Regional climate simulations for current and biofuel cropping system scenarios are evaluated using the same atmospheric forcing data over the period 1979-2004 using the Weather Research Forecast (WRF) model coupled to the NOAH land surface model. PET is projected to increase under the biofuel crop production scenario. The magnitude of the mean annual increase in PET is larger than the inter-annual variability of change in PET, indicating that PET increase is a forced response to the biofuel cropping system land use. Across the conterminous U.S., the change in mean streamflow volume under the biofuel scenario is estimated to range from negative 56% to positive 20% relative to a business-as-usual baseline scenario. In Kansas and Oklahoma, annual streamflow volume is reduced by an average of 20%, and this reduction in streamflow volume is due primarily to increased PET. Predicted increase in mean annual P under the biofuel crop production scenario is lower than its inter-annual variability, indicating that additional simulations would be necessary to determine conclusively whether predicted change in P is a response to biofuel crop production. Although estimated changes in streamflow volume include the influence of P change, sensitivity results show that PET change is the significantly dominant factor causing streamflow change. Higher PET and lower streamflow due to biofuel feedstock production are likely to increase water stress in the High Plains. When pursuing sustainable biofuels policy, decision-makers should consider the impacts of feedstock production on water scarcity.
研究表明，美国因政策驱动而扩大生物能源作物种植面积可能导致的降水量（P）和潜在蒸散量（PET）变化，会使径流量产生显著变化，并加剧美国高平原地区的水资源压力。利用耦合了诺亚陆面模型的天气研究预报（WRF）模型，在1979 - 2004年期间使用相同的大气强迫数据，对当前和生物燃料种植系统情景进行区域气候模拟。预计在生物燃料作物生产情景下，潜在蒸散量将会增加。潜在蒸散量年平均增加幅度大于其年际变化的变率，这表明潜在蒸散量的增加是对生物燃料种植系统土地利用的一种强迫响应。在美国本土，相对于照常经营的基线情景，生物燃料情景下平均径流量的变化估计在 - 56%至 + 20%之间。在堪萨斯州和俄克拉荷马州，年径流量平均减少20%，而径流量的这种减少主要是由于潜在蒸散量增加所致。在生物燃料作物生产情景下，预计年平均降水量的增加低于其年际变化，这表明需要进行更多模拟才能最终确定预测的降水量变化是否是对生物燃料作物生产的响应。尽管估计的径流量变化包括了降水量变化的影响，但敏感性结果表明，潜在蒸散量变化是导致径流量变化的显著主导因素。由于生物燃料原料生产导致的更高潜在蒸散量和更低径流量，可能会加剧美国高平原地区的水资源压力。在推行可持续生物燃料政策时，决策者应考虑原料生产对水资源短缺的影响。
