| 沙层特性对沙盖黄土坡面产流产沙变化贡献的定量分析 |
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| 引用本文： | 曹晓娟,谢林妤,张风宝,杨明义,李占斌.沙层特性对沙盖黄土坡面产流产沙变化贡献的定量分析[J].地理学报,2019,74(5):962-974. |
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| 作者姓名： | 曹晓娟 谢林妤 张风宝 杨明义 李占斌 |
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| 作者单位： | 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712100;中国科学院大学,北京100049;西安市水务局水利水土保持工作总站,西安,710018;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712100;西北农林科技大学水土保持研究所,杨凌712100;西安理工大学水利水电学院,西安,710048 |
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| 基金项目： | 国家重点研发计划(2016YFC0402406);国家自然科学基金项目(41371283);国家自然科学基金项目(41877080) |
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| 摘 要： | 沙盖黄土坡面产流产沙方式独特,侵蚀过程复杂,量化降雨过程中该类坡面产流产沙变化影响因素贡献的大小对揭示其侵蚀机理具有重要的意义。基于室内模拟降雨试验,定量分析沙层厚度（2 cm、5 cm和10 cm）和粒径组成（100%粒径≤ 0.25 mm、75%粒径≤ 0.25 mm +25%粒径> 0.25 mm、50%粒径≤ 0.25 mm+50%粒径> 0.25 mm、未处理原沙和100%粒径> 0.25 mm）在降雨过程中对产流产沙变化的影响和贡献。结果显示：沙层厚度增加能明显延长产流时间,减少总产流量,增加总产沙量,增大降雨过程中产流产沙的变异性;随沙层粒径组成变粗,初始产流时间和产沙量无明显变化规律,产流量有增大趋势。沙层厚度、粒径组成及二者交互作用对初始产流时间变化的贡献率分别为68.03%、15.77%和3.85%。沙层厚度对降雨不同时段15 min产流量和不同历时总产流量的贡献率分别在23.89%~52.22%和41.10%~48.94%之间,对相应产沙的贡献率分别在29.19%~62.01%和13.53%~30.31%之间。整体上沙层粒径组成变化对产流产沙量变化的贡献率小于沙层厚度,且无明显规律。沙层厚度和粒径组成交互作用对产流量和降雨中前期产沙量的影响显著（p < 0.05）,其对产流产沙变化的贡献率分别在13.12%~26.62%和3.22%~43.12%之间,不同降雨时段变化明显。研究结果说明,沙层厚度决定沙盖黄土坡面产流产沙过程,其和沙层粒径组成对产流产沙的影响和贡献随坡面沙层的侵蚀演化而动态变化,且二者的交互作用也不容忽视。
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| 关 键 词： | 覆沙厚度 粒径组成 径流 泥沙 贡献率 |
| 收稿时间： | 2018-07-06 |
| 修稿时间： | 2019-02-18 |
Quantifying the contributions of sand layer characteristic to variations of runoff and sediment yields from sand-covered loess slopes during simulated rainfall |
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| CAO Xiaojuan,XIE Linyu,ZHANG Fengbao,YANG Mingyi,LI Zhanbin.Quantifying the contributions of sand layer characteristic to variations of runoff and sediment yields from sand-covered loess slopes during simulated rainfall[J].Acta Geographica Sinica,2019,74(5):962-974. |
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| Authors: | CAO Xiaojuan XIE Linyu ZHANG Fengbao YANG Mingyi LI Zhanbin |
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| Abstract: | Loess slopes covered with aeolian sand are unique geomorphic features in the wind-water erosion crisscross region on the Chinese Loess Plateau. On these loess slopes, runoff and sediment production patterns are unique and complex and the thickness of covering sand and its interaction with other factors may largely interfere soil erosional responses. Therefore, quantifying the variations of runoff and sediment yields and assessing the possible factors are of great importance to understand the erosion mechanism in such unique landscapes. To quantify the effects of sand layer thickness and sand size composition on runoff generation and sediment yield, sand-covered loess slopes with 15° were subject to simulated rainfall events (intensity 1.5 mm/min) in this study. Sand layers of three different thicknesses, 2 cm, 5 cm and 10 cm, were respectively placed on loess surface. For each sand thickness, there were five kinds of compositions, i.e. 100% sand diameter ≤ 0.25 mm, 75% sand diameter ≤ 0.25 mm + 25% sand diameter > 0.25 mm, 50% sand diameter ≤ 0.25 mm + 50% sand diameter > 0.25 mm, untreated sand, and 100% sand diameter > 0.25 mm. Our results show that as sand thickness increased, it prolonged initiation time of runoff, reduced runoff yield, increased sediment yield and enhanced the variability in runoff and soil loss rates during rainfall. Our findings also indicate that with coarser sand, the total runoff loss tended to increase even though the initiation time of runoff and sediment yield was not obviously changed. The sand layer thickness, sand size composition, and their interactions respectively contributed 68.03%, 15.77%, and 3.85% to the variation of initiation time of runoff (p < 0.05), respectively. For the runoff production, the sand layer thickness can explain 23.89% to 52.22% of the variation of runoff rates during a 15-min rainfall sub-rainfall, and 41.10% to 48.94% of total runoff loss for different rainfall durations. For the sediment production, the sand layer thickness can explain 29.19% to 62.01% of the variation of soil loss rates during a 15-min rainfall sub-rainfall, and 13.53% to 30.31% the total sediment yield for different rainfall durations. Moreover, the sand size composition had less impact on runoff and sediment yields than the thickness of the sand layers. Their combined effects were significant during the early and intermediate stages (p < 0.05), and contributed to 13.12%-26.62% of runoff loss and 3.22%-43.12% of sediment yield. Overall our observations suggest that runoff and sediment generation on sand-covered loess slopes were mainly affected by the sand layer thickness rather than sand size composition, and their combined effects also varied as erosion proceeded. |
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| Keywords: | sand layer thickness particle size composition runoff sediment contribution rate |
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