不同雨强下黄土裸坡水-沙-氮磷流失耦合模拟

采用室内人工模拟降雨试验研究6种雨强3种坡度下黄土裸露坡面水沙及氮磷养分流失规律.结果表明：1）降雨强度与土壤入渗速率，坡面产流产沙量的线性拟合决定系数均大于0.8，有较好的正相关关系；2）25°黄土坡面下：NO₃^--N初始浓度较高，随降雨历时呈波动性减少，具有明显的初期冲刷效应；NH₄⁺-N初始流失浓度由90mm/h雨强下0.6057mg/L增至120mm/h的1.3076mg/L，但其浓度随降雨历时均不断减小；TN流失浓度在雨强为90，105和120mm/h时分别为0.6056，0.8011和1.3076mg/L，随雨强增大而增大；TP初始流失浓度在105mm/h时最大，90mm/h时最小，且不同雨强下TP流失浓度相互交错，不稳定；3）养分流失与坡面产流量具有较强的线性相关性，与产沙量呈显著的幂函数关系.15°坡面时，氮素流失在6种雨强下均以颗粒态为主，平均约占72%，但在雨强增大过程中，颗粒态所占比例先减少后增加；而磷素流失颗粒态所占比例均大于90%，与降雨强度和坡度均没有直接关系.

Coupling simulation of runoff-sediment-nutrient loss on loess bare sloping land under different rainfall intensities

The simulated rainfall experiment was conducted to explore the effect of rainfall intensity on coupling loss rules of runoff and sediment and nutrients under different loess bare slopes.Results showed that:1) The linear fitting coefficients between rainfall intensity and soil infiltration rate,runoff or sediment were all greater than 0.8,there were strong positive correlations;2) At 25°slope:The initial NO₃^--N concentration was high,it was decreased with increased rainfall duration,the scouring effect was significant;The initial NH₄⁺-N concentration increased from 0.6057 to 1.3076mg/L with increased rainfall intensity from 90 to 120mm/h,but NH₄⁺-N concentration decreased with increased rainfall duration;TN concentrations were 0.6056,0.8011 and 1.3076mg/L under rainfall intensities of 90,105 and 120mm/h,which increased with increased rainfall intensity;The initial TP concentration had the maximum value in 105mm/h and the minimum value in 90mm/h,and TP concentrations in different rainfall intensities were intertwined and unstable.3) There was a strong linear correlation between runoff yield and nutrient loss,while there was a significant power correlation between sediment and nutrient loss.At 15°slope:the loss forms of nitrogen was mainly in particulate state under six rainfall intensities,which approximately accounted for an average of 72%,but the proportion of particulate nitrogen decreased first and then increased with increased rainfall intensity;the contribution of particulate phosphorus accounted for more than 90%,which was no direct relation with rainfall intensity and slope.