坡面氮素流失的坡度和雨强效应模拟研究
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Effects of Slope Gradient and Rainfall Intensity on Nitrogen Loss Under Artificial Simulated Rainfall
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    摘要:

    为了研究坡面径流和壤中流中全氮(TN)的流失特征,探索坡度和雨强对TN流失的影响,以风化花岗岩母质发育的土壤为研究对象,选定坡度(5°,8°,15°,25°)和降雨强度(60,90,120,150 mm/h)作为可变量,采用原状土搬迁的方式,在室内设计的径流槽上进行人工模拟降雨试验,设计试验降雨时长为坡面径流产流后90 min,壤中流水样收集延续直至无出流为止。结果表明:(1)坡面径流TN流失浓度在产流初期快速下降,随雨强的减小或坡度的增大而增大,产流后期浓度趋于稳定且差距不大。(2)壤中流TN流失浓度均明显高于坡面径流,其流失过程规律为“上升—下降—略有上升—平稳”,总体上随雨强的减小或坡度的增大而增大。(3)坡面径流和壤中流的TN流失量均随雨强或坡度的增大而增大。壤中流是坡面TN流失的主要途径,流失比例可达91.26%~99.61%。坡面径流中TN流失量占坡面TN总流失量的比例随雨强的增大而增大。(4)雨强、流量与坡面径流、壤中流TN总流失量均呈极显著正相关,而坡度只与壤中流TN总流失量呈显著正相关。(5)在雨强90 mm/h与120 mm/h之间存在一个临界雨强,超过这个临界雨强,坡面径流TN流失量及其占总流失量的比例都会大幅上升。

    Abstract:

    In order to investigate the effects of different slope gradients (5°, 8°, 15° and 25°) and rainfall intensities (60, 90, 120 and 150 mm/h) on TN (total nitrogen) loss in surface runoff and subsurface flow, an artificial simulated rainfall experiment was conducted, and decomposed granite soil was taken as the experiment object. As the test design, the rainfall duration was 90 min after the appearance of surface runoff, and the test ended up when the subsurface flow disappeared. The results showed that: (1) The loss concentrations of TN in surface runoff declined rapidly at the early stage, and increased with the reduction of rainfall intensity and the increasing of slope gradient, and then tended to be stable. (2) The loss concentrations of TN in subsurface flow were significantly higher than those in surface runoff, and the curves of TN loss concentration in subsurface flow all followed a law of “rising-falling-slightly rising-steady”. Generally, the loss concentrations increased with the reduction of rainfall intensity and the increasing of slope gradient. (3) The total losses of TN in surface runoff and subsurface flow were both increased with the increasing of rain intensity and slope gradient. Subsurface flow was the main approach of TN loss on slope, and its proportion could reach 91.26% to 99.61%. The proportion of TN loss in surface runoff increased with the enhancement of rainfall intensity. (4) Rainfall intensity and runoff volume were both extremely significantly positively related to the TN loss in surface runoff and subsurface flow, while slope gradient only significantly positively correlated with the TN loss in subsurface flow. (5) There was a critical rainfall intensity between 90 mm/h and 120 mm/h, over which, the TN loss in surface runoff and its proportion in total loss would sharply rise.

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邬燕虹, 张丽萍, 邓龙洲, 范晓娟.坡面氮素流失的坡度和雨强效应模拟研究[J].水土保持学报,2018,32(2):27~33

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  • 在线发布日期: 2018-04-18
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