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| 黄土丘陵区坡面薄层水流动力学特性及其对土壤侵蚀的影响 |
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安妙颖1,2,韩玉国1,2*,王金满3,徐磊4,王秀茹1,2,庞丹波1
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| (1.北京林业大学 水土保持学院 水土保持国家林业局重点实验室, 北京 100083;2.山西省吉县森林生态系统国家野外科学观测研究站, 山西 吉县 042200;3.中国地质大学(北京)土地科学技术学院/国土资源部土地整治重点实验室, 北京 100083;4.中国灌溉排水发展中心, 北京 100054) |
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| 摘要: |
| 为奠定基于运动力学参数构建土壤侵蚀模型的理论基础，通过不同降雨强度(25、50和75 mm/h)、不同坡长(1、5、10、15和20 m)下径流小区内人工模拟降雨试验，对不同处理下坡面薄层水动力学特性进行分析，并对水动力学参数与土壤侵蚀之间的关系进行初步探讨。结果表明:当坡度一定时，坡面平均流速主要受坡长及单宽流量影响，降雨强度通过影响单宽流量的大小间接影响坡面平均流速；在试验设计范围内，当坡长>1 m时，整体上呈“层流-急流态”，当坡长为1 m时，整体上呈“层流-缓流态”；当降雨强度一定时，雷诺数随着坡长的增加线性增加，佛汝德数随着坡长的增加以幂函数形式增加；降雨强度对坡面流有明显的“增阻”效应；坡面阻力系数随着坡长的增加呈幂函数减小趋势；坡面平均土壤侵蚀率与单宽流量间呈一元线性趋势增加，与水流平均流速间呈指数函数增加，与雷诺数间呈二次函数增加。 |
| 关键词: 黄土丘陵区 坡面流 水动力学特性 土壤侵蚀 |
| DOI：10.11841/j.issn.1007-4333.2020.02.15 |
| 投稿时间：2019-04-23 |
| 基金项目:中央高校基本科研业务费专项资金(BJFUKF201801)；国家自然科学基金(51879005) |
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| Hydrodynamic characteristics of overland flow and its impact on erosion in Loess Hilly RegionAN Miaoying1, 2, HAN Yuguo1, 2*, WANG Jinman3, XU Lei4, WANG Xiuru1, 2, PANG Danbo1 |
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AN Miaoying1,2,HAN Yuguo1,2*,WANG Jinman3,XU Lei4,WANG Xiuru1,2,PANG Danbo1
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| (1.School of Soil and Water Conservation, Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China;2.Forest Ecosystem Studies, National Observation and Research Station, Jixian 042200, China;3.School of Land Science and Technology/Key Laboratory of Land Consolidation and Rehabilitation of Ministry of Land and Resources, China University of Geosciences(Beijing), Beijing 100083, China;4.China Irrigation and Drainage Development Center, Beijing 100054, China) |
| Abstract: |
| Overland flow is the main source of soil erosion. Research on the hydrodynamic characteristics and its impact on soil erosion are important to deeply understand the mechanism of soil erosion. In recent years, numerous studies have focused on the characteristics of overland flow on slopes, which ignored the role of slope hydrodynamics in soil erosion mechanisms. In this study, the characteristics of overland flow and its impact on soil erosion were analyzed by conducting artificial simulation experiments in runoff plots with different slope lengths(1, 5, 10, 15 and 20 m)under different rainfall intensities(25, 50 and 75 mm/h). The results showed that the average velocity was mainly affected by the lengths of slope and the discharge per unit width, whereas the rainfall intensity indirectly affected the average velocity by influencing the discharge per unit width. The overland flow presented laminar torrent pattern when the slope length was greater than 1m and laminar subcritical pattern when the slope was 1 m. When the rainfall intensity was constant, the Reynolds number increased linearly with the increase of slope length, and the Froude number increased with the increase of the slope length as a power function. The rainfall intensity displayed a significant “drag- increasing” effect on overland flow. The slope resistance coefficient decreased in power function with the increase of slope length. The average soil erosion rate on slope increased with the discharge per unit width linearly, with the average velocity exponentially and the Reynolds numbers quadratically. |
| Key words: Loess Hilly Region overland flow hydrodynamic characteristics soil erosion |
