中文摘要：

壤中流是土石山区降雨径流的重要组成部分,也是养分流失的重要途径。通过对陕西省石泉县后沟小流域2011年汛期3场自然降雨过程条件下玉米和辣椒径流小区壤中流过程对硝态氮（NO3--N）迁移流失影响研究,结果表明,在3场典型自然降雨过程中,2个径流小区内产生的壤中流量占总径流量的比例均大于74.3%;而且大雨强短历时降雨过程下壤中流的流量较小,小雨强长历时的降雨过程容易形成壤中流流量较大;作物的前期和中后期生长阶段的壤中流占总径流量比例是作物收获和土地空置阶段壤中流比例的1.14～1.35倍。在3场自然降雨过程中,由壤中流携带的硝态氮流失量占径流小区硝态氮流失量的87.81%～98.99%,表明壤中流是坡耕地NO3--N的流失的最重要载体。因此,加强壤中流管理对于汉江水源区坡耕地面源污染控制管理和南水北调中线工程引水水质安全有重要的参考意义。

英文摘要：

Based on natural rainfall processes,effects of nitrate-N（NO-3-N） loss by subsurface flow in corn（Zea mays）and chilies（Capsicum frutescens L.） runoff plots in 2011 flood season in Hougou watershed of Shiquan county,Shaanxi province.The results show that the subsurface flow takes up of more than 74.3% in total amount of runoff.Moreover,during the heavy rainfall intensity and short duration rainfall,the volume of subsurface flow is small.However,during the small rainfall intensity and long duration rainfall,the volume of subsurface flow is large.In addition,the subsurface flow ratio is 1.14~1.35 times at the seedling stage and the vigorous stage.During the processes of three monitored natural rainfall in 2011 flood season,the loss amount of NO-3-N by subsurface flow takes up of more than 87.81% in total amount of NO-3-N,which indicates subsurface flow is the main carrier for NO-3-N loss,meanwhile,NO-3-N loss is being aggravated by local agricultural practices.The research has a great significance to the non-point source pollution management and water quality of the middle route of south-to-north water diversion project.