次降雨有效降雨量的影响因素及其估算模型

Investigating Effective Rainfall and Factors Affecting Effective Rainfall Using Experiments and Modelling

利用沧州市南皮生态农业试验站点2011—2013年不同土层深度的含水率及降雨量和降雨时间,结合由植株叶面积指数得到的不同生育期植株的截留容量,分析了最大容水量S和最大降雨强度二者与降雨有效性的相关关系,并在此基础上建立了次降雨有效降雨的估算模型。结果表明,土壤初始含水率与降雨有效性线性相关,且在不发生溢流情况下,可以用土壤最大容水量S作为是否考虑土壤初始含水率折减作用的分界点;另外,对于降雨强度I≥0.7 mm/min的降雨,降雨强度与降雨有效性相关性显著,并且随最大降雨强度的增大,降雨有效性逐渐减小;最后将运用传统模型和新估算模型计算的有效降雨量值与实测有效降雨量值验证对比,新模型比传统模型更加贴近实测有效降雨,并且降雨量较大时差别更加明显。

This paper analyzed the maximum holding capacity of water by soil, rainfall intensity and effective rainfall（portion of a rainfall staying in root zone） based on rainfalls and soil water content profiles measured at Nanpi Agro-ecological Experimental Station in Cangzhou from 2011 to 2013. The interception of rainfalls by canopy at different growing periods was calculated using leaf area and leaf index. A quantitative relationship between the effective rainfall and rainfall was proposed. The results showed that the initial soil water content was linearly correlated to the effective rainfall. In the absence of surface runoff, the maximum holding capacity of water by soil could be used as a threshold of whether a reduction in initial water content should be considered. In addition, when rainfall intensity was higher than 0.7 mm/min, the correlation between rainfall intensity and effective rainfall was significant, and with the increase in maximum rainfall intensity, the effective rainfall decreased.Comparing the effective rainfall calculated using the traditional model and the proposed model with the measured results showed that the proposed model was more accurate, especially for large rainfalls.