SRA1B情景下中国主要作物需水预测

Crop water demand in China under the SRA1B emissions scenario

分析气候变化下中国主要作物需水规律,有助于从粮食安全与水资源可持续利用角度应对气候变化。根据IPCC提供的SRA1B情景下大气环流模式MIROC3.2的输出,利用FAOPenman-Monteith公式计算参考作物腾发量;根据FAO作物系数、SAGE作物分布与柯本气候分类,得到计算单元的作物系数,根据参考作物腾发量与作物系数估算作物需水量;考虑需水与有效降水旬尺度的随机匹配,预测SRA1B情景下未来50年中国各地区主要作物的灌溉需水量。结果表明,参考作物腾发量总体上呈上升趋势,全国平均增加约8%;作物需水量总体上呈增加趋势,东北地区平均增加约10%;灌溉需水量总体上呈增加趋势,东北与华南增加显著。分析表明,SRA1B情景下气温升高是作物需水量增加的主要原因,降水的增加使华北地区灌溉需水量的增加不显著,降水的减少使东北与华南灌溉需水量显著增加。

Projections of the crop demand under future climate scenarios would help us to understand the potential in- fluence of climate change on food safety and water resources. Using the United Nations Food ＆ Agriculture Organization （FAO） modified Penman-Monteith equation and the output from the Model for interdisciplinary Research on Climate （MIROC3.2） for the SRA1B emissions scenario, the reference evapotranspiration （ETo ） can be calculated for China for the next 50 years. Using the FAO crop coefficients and the Koppen climate classification system, the crop coefficient can thus be determined for every calculation unit. The estimation of crop water demands is achieved using ETo and the crop coefficient, and the corresponding irrigation water requirement can also be worked out by matching the effective precipitation with the crop water demand. The result shows that on average, China~ ETo could increase by about 8% , and so does for the crop water demand and the irrigation water requirement. Over the northeast region, this increase in irrigation water requirement could reach above 10% , and the increase over South China is also signifi- cant. The upward trends in water demands are mainly due to the increase in future temperatures, which can result in an increase of ETo values. The matter could be further complicated by the reduction of the projected precipitation for the northeast and south regions of China. However, the projected increase in precipitation over the north region could moderate the issue of water demands.