| 典型黄土坡面土壤侵蚀特征及径流流速空间变化试验研究 |
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| 引用本文： | 和继军,黎雪晴,蔡强国,孙莉英,王硕.典型黄土坡面土壤侵蚀特征及径流流速空间变化试验研究[J].地理研究,2022,41(5):1327-1337. |
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| 作者姓名： | 和继军 黎雪晴 蔡强国 孙莉英 王硕 |
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| 作者单位： | 1.首都师范大学,城市环境过程和数字模拟国家重点试验室培育基地,北京资源环境与GIS重点试验室,北京 1000482.中国科学院水利部水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌 7121003.中国科学院地理科学与资源研究所,陆地水循环与地表过程重点试验室,北京1001014.中国科学院大学资源与环境学院,北京 100049 |
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| 基金项目： | 国家自然科学基金项目（52179071、41977069、41771314）； |
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| 摘 要： | 为了明确土壤性质对坡面侵蚀方式作用机制的影响,本研究采用室内模拟降雨试验,选取黄土高原典型暴雨强度,在不同坡度条件下,对两种黄土的坡面侵蚀方式、形态特征、产流产沙过程及其相应径流流速的变化规律进行了研究。结果表明,绥德土径流量明显高于安塞土,10º、15º和20º时前者的平均径流量分别比后者高出51.1%、55.5%和63.0%,且前者更易形成细沟,使得其平均含沙量和平均产沙率分别是后者的1.14~3.59倍和2.50~8.48倍。在片蚀阶段,与绥德土相比,安塞土的含沙量较高,后者的平均含沙量是前者的1.24~1.73倍,但两种土壤的含沙量和产沙规律相同,均表现为先快速增加到最大值,然后逐渐降低到相对稳定状态,该现象证明片蚀的初期阶段主要受控于径流输沙能力,后期受径流的剥蚀能力控制。在细沟侵蚀阶段,绥德土细沟发育以沟头溯源侵蚀为主,崩塌作用频繁,该侵蚀形式不仅控制着细沟形态的总体特征,也导致含沙量和产沙率均急剧增加,该阶段平均含沙量是相应片蚀阶段的3.25~4.34倍。细沟沟口下方坡面存在明显的泥沙沉积带,表明细沟集中水流的搬运能力远高于坡面漫流,细沟侵蚀主要受径流输沙能力控制。两种土壤的径流流速均表现为坡面下部高于坡面上部,径流稳定后高于径流稳定前,总体来看,绥德土和安塞土上坡和径流稳定后的平均流速分别是下坡和径流稳定前的1.4倍、1.25倍和1.75倍、1.29倍,此外细沟侵蚀或侵蚀强度与微地貌形态之间的互馈作用对径流流速也有较大影响。
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| 关 键 词： | 片蚀 跌坎 细沟侵蚀 泥沙沉积 径流流速 |
| 收稿时间： | 2021-03-02 |
Experimental study on soil erosion characteristics and spatial variation of runoff velocity on typical loess slopes |
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| HE Jijun,LI Xueqing,CAI Qiangguo,SUN Liying,WANG Shuo.Experimental study on soil erosion characteristics and spatial variation of runoff velocity on typical loess slopes[J].Geographical Research,2022,41(5):1327-1337. |
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| Authors: | HE Jijun LI Xueqing CAI Qiangguo SUN Liying WANG Shuo |
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| Abstract: | In order to clarify the mechanism of soil properties affecting erosion form of Loess Plateau, this study uses indoor simulated rainfall tests, and the typical rainfall intensity, to analyze the slope erosion forms, morphological characteristics, runoff and sediment yield processes and corresponding changes of runoff velocity of two types of loess under different slope conditions. The results show that the runoff of Suide soil is obviously higher than that of Ansai soil. On 10º, 15º and 20º slopes, the average runoff rates of Suide soil are 51.1%, 55.5% and 63.0% higher than those of Ansai soil, respectively. In terms of the form of erosion, Suide soil is more likely to form rill, and the average sediment concentration and yield of Suide soil are 1.14-3.59 times and 2.50-8.48 times of Ansai soil, respectively. During the sheet erosion stage, Ansai soil has a higher sediment concentration, which is 1.24-1.73 times that of Suide soil. Therefore, the two types of soil have the same change law of sediment concentration and sediment yield, and they both increase rapidly to a maximum value, and then gradually decrease to a relatively stable state. Sheet erosion can be divided into two erosion stages, the initial stage controlled by a transport-limited condition and the subsequent stage controlled by erosion-limited condition. During the rill erosion stage, the development of rill is dominated by headcut advance and its frequent collapse. This erosion form not only affects the characteristics of rill morphology, but also leads to a rapid increase in both the sediment concentration and sediment yield, the average sediment concentration is 3.25-4.34 times of that in sheet erosion stage, and there is an obvious sediment deposition belt below the rill mouth. This indicates that the transport capacity of rill flow is much higher than that of sheet flow, and rill erosion is mainly controlled by a transport-limited condition. The runoff velocity of both types of soil increases as the distance from the top of the slope increases, and the velocity after the runoff stabilizes is higher than that before the runoff stabilizes. Overall, the average flow velocities of Ansai soil and Suide soil on the upslope and after runoff stabilization are 1.75 times, 1.29 times and 1.4 times, 1.25 times of that on the downslope and before runoff stabilization, respectively. At the same time, the interaction between the rill erosion or the erosion intensity and the micro-morphology could also affect the runoff velocity. |
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| Keywords: | sheet erosion drop pit rill erosion sediment deposition runoff velocity |
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