模拟降雨对工程建设区裸露坡地产流产沙及氮素流失的影响

为揭示不同降雨强度下工程建设区裸露坡地土壤侵蚀过程和氮素流失特征,采用人工模拟降雨的方法,研究不同降雨强度(1,1.5,2mm/min)和处理(裸地、坡面覆盖纱网)对工程裸露坡地产流产沙及氮素流失的影响。结果表明:(1)径流强度、径流含沙量、土壤剥蚀率都与降雨强度呈正相关关系,土壤入渗率与降雨强度呈现负相关关系。(2)累积泥沙量与累积径流量在裸地处理中呈现线性函数关系,在纱网处理中呈现幂函数关系。(3)地表径流中氮素流失浓度随降雨历时呈现"下降—稳定"趋势,氮素流失量随降雨强度的增加而增大,其中NO_3~-—N流失量占总氮比重高于NH_4~+—N。(4)土壤坡面覆盖纱网后能有效控制水土流失量和氮素流失量,其中径流量和NO_3~-—N流失量在小雨强处降低效果显著,分别降低了60.21%和56.74%;TN流失量和NH_4~+—N流失量在小、中雨强处降低效果较好,均达到59.26%以上;侵蚀泥沙量在小、中、大雨强处均降低了79%以上。说明土壤坡面覆盖纱网这一措施对降低工程建设区裸露坡地土壤侵蚀量和氮素流失量具有效果显著,可以作为工程建设区水土流失防止措施。

Research on Runoff, Sediment and Nutrient Loss Characteristics on Bare Slopes in an Engineering Construction Area Under Artificially Simulated Rainfall

In order to reveal the processes of soil erosion and the characteristics of nitrogen loss on bare slopes under different rainfall intensity,by using artificial rainfall simulation device,we simulated rainfall of three intensities (1,1.5,and 2 mm/min) and set two processing method (bare land,slope covered with yarn net) to find out the characteristics of surface runoff and nitrogen loss under different rainfall intensity.The results were as follows:(1) Runoff intensity,runoff sediment concentration,and soil erosion rate were positively correlated with rainfall intensity,while soil infiltration rate and rainfall intensity was negatively correlated.(2) Cumulative runoff and sediment yield in the bare ground showed a linear correlation,while in the yarn net covered treatment they showed a power function relation.(3) Nitrogen loss in surface runoff decreased with the duration of rainfall,the amount of nitrogen loss increased with the increase of rainfall intensity,nitrate-nitrogen loss accounted for a higher proportion of total nitrogen than ammonium-nitrogen.(4) Soil erosion and nitrogen loss could be effectively controlled by covering the slope with yarn net,runoff and nitrate nitrogen loss decreased by 60.21％ and 56.74％ under the 1mm/min rainfall intensity,respectively;the amount of total nitrogen and ammonium nitrogen loss could be reduced by more than 59％ under the 1 and 1.5 mm/min rainfall intensity;the amount of eroded sediment was decreased by more than 79％ under all three rainfall intensities.The results showed that the yarn net coverage could effectively control the amount of soil erosion and nitrogen loss on the care slope of in the engineering construction area,and this research can provide a reference for the prevention and control measures of soil and water loss in engineering construction areas.