冬小麦冠层降雨截留过程及其模拟研究

冬小麦冠层截留直接影响冬小麦对降雨的有效利用,通过模拟降雨试验和统计分析,系统研究了降雨量、降雨强度对冬小麦冠层截留特征的影响,建立了适于降雨冬小麦冠层截留的模型。结果表明:棵间雨量与降雨量呈显著的正相关关系(P<0.01);冠层截留量与降雨量呈显著的幂函数关系(P<0.01)。降雨强度与棵间雨量百分比呈负指数函数关系(P<0.01),与冠层截留量百分比呈负幂函数关系(P<0.01)。不同降雨强度下冬小麦冠层截留过程趋势一致,降雨强度越小,其达到冠层截留容量时所需时间越长。降雨强度对冠层截留容量没有明显影响。在雨量恒定条件下,冠层截留量随雨强的增加而减小,呈明显的负相关关系。叶面积指数(leaf area index,LAI)与冬小麦冠层截留容量呈正相关关系(P<0.01)。构建了具有较好截留机制的冬小麦冠层降雨截留过程模型,并基于模拟降雨和天然降雨的数据拟合了模型参数,表征冬小麦降雨蒸发能力的参数α为0.008。模拟值和实测值有较好的一致性,显示了修正模型适用于冬小麦冠层截留计算。

Study on Winter Wheat Canopy Interception Process of Rainfall and Simulation

The effective utilization of rainfall by winter wheat was directly influenced by canopy interception.Influences of rainfall and rainfall intensity on characteristics of canopy interception of winter wheat were studied by simulative rainfall experiment and statistical analysis,and a canopy interception model suitable for winter wheat was established.The results showed that throughfall was significantly positively related with rainfall(P<0.01),while relationships between canopy interception and rainfall significantly showed a power function(P<0.01).A negative exponential correlation between rainfall intensity and percentage of throughfall(P<0.01) and a negative power correlation between rainfall intensity and percentage of interception(P<0.01) were found.The trend of canopy interception of winter wheat was consistent under different rainfall intensities,while the duration to reach the canopy interception capacity was longer with lower rainfall intensity.Rainfall intensity had no significant influence on canopy interception capacity of winter wheat.Interception decreased with the increase of rainfall intensity,indicating a negative relation with rainfall intensity at the constant rainfall conditions.Canopy interception capacity of winter wheat showed a positive correlation with LAI(P<0.01).A mechanism model for rainfall interception process of the winter wheat was developed,and the model parameters were fitted based on the measured data both from the natural rainfall experiment and simulated rainfall experiments.A parameter,α,indicating evaporative capacity of rainfall intercepted by winter wheat canopy,was set to 0.008.Simulated values were consistent with measured ones,indicating that the improved model can be used for estimating rainfall interception of winter wheat canopy.