摘要
为研究耕作对浅沟径流产沙及形态发育特征的影响,在野外调查的基础上,设计坡度（15°、20°、25°）、雨强（1.0、1.5、2.0 mm/min）及放水流量（7.53∽23.45 L/min）3个处理,采用室内模拟降雨和放水冲刷的方法,测定了不同处理下浅沟径流量、产沙量。结果表明：1）2种浅沟水流均为紊流,耕作使浅沟水流雷诺数和弗劳德数分别减小0.95%∽30.77%、2.64%∽39.14%,阻力系数和糙率系数分别增加4.01%∽58.82%、0.88%∽27.87%;2）试验条件下,耕作使浅沟土壤剥蚀率增大9.48%∽37.87%,未耕作与耕作浅沟土壤剥蚀率分别与坡度—流量交互作用、雨强—坡度交互作用呈极显著线性关系,土壤剥蚀率与径流剪切力、径流功率及单位径流功率均呈显著的线性关系,未耕作浅沟发生剥蚀的临界剪切力、临界功率及临界单位径流功率分别为17.576 N/m2、5.036 W/（m2·s）、0.0381 m/s,耕作浅沟为10.585 N/m2、3.544 W/（m2·s）、0.0277 m/s;3）耕作使浅沟宽度增加1.98%∽31.79%,浅沟面积增大0.84%∽32.03%,下切深度降低2.82%∽26.67%;4）耕作使浅沟土壤侵蚀量增加0.91%∽22.80%,未耕作和耕作浅沟土壤侵蚀量分别占坡面土壤侵蚀总量的44.09%∽74.16%和42.44%∽56.44%,与雨强—流量交互作用均呈极显著的线性函数关系。结果可为该区浅沟侵蚀预测模型的建立及农业生态环境安全与保护提供科学依据。
In the hill-gully area of the Loess Plateau, serious man-made soil and water loss occurs in disturbed soils of sloping farmlands formed in the process of tillage operation. Frequent farming activities cause ephemeral gullies to develop continuously on sloping farmlands. Although an ephemeral gully may be refilled and rehabilitated, new ephemeral gully may develop in the original position in next rainy season. An indoor flow scouring experiment under artificially simulated rainfall was carried out in the State Key Laboratory of Soil Erosion and Dryland Agriculture on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, China in July 2014. The effects of tillage treatments on runoff and sediment yielding in ephemeral gully and its morphology were investigated at different rainfall intensities and slope degrees under the condition of upslope concentrated flow. Based on preliminary field investigations, 3 slope degrees of 15°, 20° and 25° were selected. Rainfall intensity was designed at 1.0, 1.5, and 2.0 mm/min. Flow discharges were 7.53 to 23.45 L/min. Plots of 8 m×1m were laid out for experiments and 3 flow sections were set up for runoff and sediment measurements. Before each test, rainfall intensity was calibrated repeatedly until the rainfall uniformity coefficient reached 85% or above. During each test, flow velocity was measured with dye tracing method and flow width and depth were measured with point gauge system. Runoff sample was taken once a minute within 3 minutes before runoff generation, and once 3 minutes after runoff generation. The results showed that： 1） Flow regimes for non-tilled and tilled ephemeral gullies were characterized by turbulent flow; Tillage could decrease Reynolds number and Froude number by 0.95%-30.77% and 3.41%-35.66%, and increase Darcy-Weisbach coefficient and Manning roughness coefficient by 4.01%-58.82% and 0.88%-27.87%, respectively; and 2） Compared to non-tilled ephemeral gully, the soil detachmen
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2015年第15期114-123,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金(40471080
41301299)
中国科学院知识创新工程重大项目(KZZD-EW-04-03)
关键词
耕作
径流
产沙
黄土区
坡耕地
浅沟
形态特征
cultivation
runoff
sediments
Loessial region
sloping farmland
ephemeral gully
morphological characteristic
