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金沙江干热河谷冲沟沟床草被对径流产沙过程的影响机理
Alternative TitleInfluence mechanism of grass belt to sediment production process of runoff in gully beds in Jinsha River Dry-hot Region, Southweat China
Language中文
杨丹
Thesis Advisor草被带长度 ; 茎秆直径 ; 水动力特性 ; 产沙过程 ; 金沙江干热河谷
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士
Degree Discipline自然地理学
Keyword熊东红
Abstract本研究以金沙江干热河谷为研究区,依托中国科学院水利部成都山地灾害与环境研究所与云南省农业科学院合建的元谋干热河谷沟蚀崩塌观测研究站(以下简称元谋站),根据野外调查结果,构建冲沟模拟试验小区,并采用放水冲刷试验,研究沟床草被特征(草被带长度和茎秆直径)对径流水动力特性和产沙过程的影响机理。研究结果对于深刻揭示草被影响冲沟径流过程、促进冲沟稳定的机理机制具有重要意义,有利于优选出最佳沟床草被布局,有的放矢地采取植被措施指导冲沟治理实践,对地貌学和土壤侵蚀学中关于冲沟发育动力过程及稳定机制的阐述起到一定的补充和完善作用。主要结论如下: 1)沟床草被对径流水动力特性的影响。综合分析了不同长度和不同茎秆直径的草被带对径流剪切力、阻力系数、总能耗等水动力参数的影响及其在时空上的变化规律。草被带对径流剪切力有明显消减作用,草被带越长,径流剪切力越小,16m长草被带小区剪切力均值(3.45Pa)远小于无植被裸地小区(6.81Pa);对径流阻力系数和总能耗有增大作用,且草被带越长、茎秆直径越大阻力系数和总能耗越大。径流剪切力和阻力系数均在时空上表现出增大趋势。 2)沟床草被对产沙特性的影响。沟床径流泥沙含量随着草被带长度和茎秆直径的增大成明显的减小趋势(裸地小区泥沙含量均值为0.51g/ml,16m长草被带小区泥沙含量均值为0.08g/ml)。径流泥沙含量从沟床上游往下游方向不断增大,但随着草被带长度和茎秆直径的增大,泥沙含量在沟床径流方向上的增大速率有减小趋势。8~12m长草被带是本研究中径流泥沙含量显著降低的临界草被带长度。 3)径流水动力参数对产沙特性的影响。沟床径流泥沙含量随径流阻力系数的增大呈减小趋势,随径流剪切力和总能耗的增大成增大趋势。不同沟床草被带长度和茎秆直径下,泥沙含量与总能耗的拟合关系存在一定差异。 4)本试验条件下,草被带长度为8~12m是增大径流阻力,降低径流剪切力,控制径流泥沙含量的最佳草被带长度范围;98mm茎秆直径是增大径流阻力,降低剪切力的最佳草被茎秆直径。
Other AbstractThe study area locates in Jinsha River Dry-hot Valley, relying on Yuanmou Dry-hot Valley Gully Erosion and Collapse Observation Research Station of Institute of Mountain Hazards and Environment, Chinese Academy of Sciences. Constructing simulation experimental plots based on the field investigation to study the influence mechanism of grass belt length and culm diameter to hydrodynamic properties and sediment transport process of runoff. The study results revealed the impact of grass belt in gull beds to runoff resisitance and energy consumption, were benfical to optimize the gully bed grass belt layout and take purposeful measures to promote gully. The main contents and conclusions of this study are listed as follows: 1) Impact of grass belt length to hydrodynamic properties. The influence of grass belt to shear stess, runoff resistance coefficient, and energy consumption of runoff were analysed. Besides, we analysed the spatial and temporal variety regulation of above-mentioned hydrodynamic properties. The study result shows that grass belt has important effects on reducing shear stress of runoff(the shear stress of runoff in Plot 1 and Plot 5 are 6.81Pa and 3.45 Pa,respectively), and increasing runoff resistance coefficient and energy consumption. 2) Impact of grass belt to sediment yield characteristics. With the increasing the length and culm diameter of grass belt, the sediment concentration of runoff has a tendency to decrease (the average sediement concentration in Plot 1 and Plot 5 are 0.51g/ml and 0.08g/ml, respectively). Sediment concentration gradually becomes stable after steep decline in fisrt with the change of time.The sediment concentration has a tendency to increase with the increase rate gradually decreasing along the gully bed extend direction. The 8m grass belt is the critical length to control and reduce sediment concentration in preventing soil and water erosion. 3) Impact of hydrodynamic properties to sediment concentration of runoff in gully bed. The sediment concentration of runoff decreased along with the increase of resistance coefficient, and increased with the increase of shear stress and energy consumption of runoff. The length and culm diameter of grass belt have important influence on the fitting relationship between hydrodynamic properties and sediment concentration. 4) The study result shows: i) it can effectively control soil erosion in gully bed when the grass belt’s length is 8~12m; ii) when the culm diameter is 98mm, the grass belt can maximumly increase the runoff resistance coefficient and decrease runoff shear stress.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/8011
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
杨丹. 金沙江干热河谷冲沟沟床草被对径流产沙过程的影响机理[D]. 北京. 中国科学院研究生院,2014.
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