【摘要】 坡面土壤侵蚀及养分流失是造成土地生产力下降、地表水体富营养化等环境问题的主要原因.采用物理模型对次降雨条件下坡面径流量、侵蚀量及养分流失量进行准确估算具有重要意义.本文通过不同降雨强度(20、50、75mm/h)、不同坡长(1、5、10、15、20m)下径流小区内人工模拟降雨试验,分析了坡面径流侵蚀特征及总氮(TN)流失特征,构建了估算坡面总氮流失量的经验模型,并将其嵌入基于次降雨的KINEROS2(A Kinematic Runoff and Erosion Model)模型中进行模拟验证.结果表明:降雨强度是影响坡面径流率、侵蚀率及总氮流失率的主要因素;降雨强度、坡长及其交互作用与径流量、侵蚀量之间呈多项式关系(决定系数R~2>0.95);坡面总氮主要以结合态的形式流失,且坡面TN流失量与径流量、侵蚀量之间呈一元线性关系(R~2>0.92);KINEROS2对次降雨条件下坡面径流量、侵蚀量的模拟精度较高(相对误差RE,0.03%～11.31%);嵌入坡面TN流失模型的KINEROS2对径流中TN流失量、泥沙中TN流失量及坡面TN流失量模拟效果较好(R~2>0.91,纳什系数NSE>0.76).更多还原

【Abstract】 Soil erosion and nutrient loss are major causes of decline in land productivity,water eutrophication and other environmental problems.It is important to estimate the amount of runoff,erosion and nutrient loss on slope under rainfall events by a physical model.In this study,characteristics of runoff,erosion and total nitrogen(TN) loss were analyzed by artificial simulation test in runoff plots with different slope lengths under different rainfall intensities,an empirical model was established,and by embedding this model into the kinematic runoff and erosion model(KINEROS2),total nitrogen loss on slope was simulated.The results indicated that rainfall intensity is the main factor affecting the runoff rate,erosion rate,and total nitrogen loss rate.There is a polynomial relationship between rainfall intensity,slope length and their interaction with amount of runoff and erosion(Coefficient of determination R~2>0.95).The TN on slope is mainly lost in a combined state,and there is a linear relationship between the loss of TN and the amount of runoff and erosion(R~2>0.92).KINEROS2 can simulate the amount of runoff and erosion under individual rainfall events more accurately(Relative Error(RE),0.03%～11.31%).By embedding the empirical model into KINEROS2,TN loss in runoff,in erosion and on slope under individual rainfall events was better simulated(R~2>0.91;Nash-Sutcliffe efficiency coefficient(NSE)>0.76).更多还原