元谋干热河谷冲沟发育区土体抗冲性及其影响因素研究

发布时间：2018-02-20 01:21

本文关键词： 不同活跃程度冲沟侵蚀土体抗冲性影响因素干热河谷　出处：《四川农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：冲沟侵蚀是造成元谋干热河谷生态环境脆弱、水土流失严重等问题的主要根源之一：土壤抗冲性是揭示土壤侵蚀机理的重要指标,也是土壤侵蚀领域的研究热点和难点问题之一。开展干热河谷极端环境(特殊的气候条件、复杂的岩土性质)下土体抗冲性研究,从抗冲性指数的空间分布特征揭示冲沟侵蚀规律,为区域生态修复与水土保持工作提供理论指导。为探明干热河谷不同活跃程度冲沟土体的抗冲性能,本研究选取活跃、较活跃和稳定这三类冲沟的沟头、沟床及其集水区的表层土体,设置了0%,50%和100%三个不同初始含水率的处理。采用原状土水槽冲刷试验和室内理化性质分析实验的方法,研究了不同活跃程度冲沟土体的理化性质差异、不同部位土体抗冲性变化特征、不同初始含水率条件下冲沟土体抗冲系数动态变化特征,并分析了冲沟土体抗冲性的影响因素。研究结果表明：(1)随冲沟活跃程度从活跃、较活跃到稳定状态变化,冲沟土体的理化性质相应发生变化。不同活跃程度冲沟土体理化性质大小为：土体容重、砂粒含量、内摩擦角在活跃冲沟最大,在稳定冲沟最小,表现为活跃较活跃冲沟稳定冲沟：土体总孔隙度、田间持水率、粘聚力、粉粒含量、粘粒含量则相反,其含量高低依次为活跃冲沟较活跃冲沟稳定冲沟。(2)不同活跃程度冲沟发育区各部位(沟头、沟床和集水区)的径流含沙量均随时间的增加而减小。三类冲沟的径流含沙量为活跃冲沟较活跃冲沟稳定冲沟：不同活跃度冲沟主要产沙部位也不大一致,活跃和较活跃冲沟产沙部位主要为沟头,稳定冲沟主要产沙部位为沟床。(3)不同初始含水率条件下土体抗冲性均与时间呈现幂函数递增关系。初始含水率为0%条件下,冲沟发育区各部位抗冲性大小表现为：活跃冲沟集水区沟床沟头,较活跃冲沟沟床集水区沟头,稳定冲沟沟头沟床集水区；初始含水率为50%条件下,冲沟各部位抗冲性大小为：活跃冲沟集水区沟床沟头,较活跃冲沟沟床集水区沟头,稳定冲沟沟头沟床集水区；初始含水率为100%时各部位抗冲性大小表现为活跃冲沟沟床集水区沟头,较活跃集水区沟床沟头,稳定冲沟沟床沟头集水区。表明干热河谷区冲沟在不同含水率下,活跃和较活跃冲沟的沟头、稳定冲沟的集水区土体抗冲性最小,极易受径流冲刷侵蚀,应重点治理活跃、较活跃冲沟沟头,重视稳定冲沟集水区的保护。(4)在不同含水率条件下冲沟土体抗冲性的影响因素不尽相同。活跃冲沟土体抗冲性与抗剪强度(内摩擦角、黏聚力)、黏粒含量与各类生物多样性指标显著正相关,与砂粒含量显著负相关；较活跃冲沟土体抗冲性与Simpson指数、丰富度、多度显著正相关,与砂粒含量显著负相关；稳定冲沟抗冲性与黏粒含量显著正相关,与田间持水率、粉粒含量、砂粒含量和生物多样性指标显著负相关。
[Abstract]:Gully erosion is one of the main causes of the fragile ecological environment and serious soil erosion in Yuanmou dry-hot valley. Soil erosion resistance is an important index to reveal the mechanism of soil erosion. It is also one of the hot and difficult problems in the field of soil erosion. Based on the spatial distribution characteristics of scour resistance index, the rule of gully erosion is revealed, which provides theoretical guidance for regional ecological restoration and soil and water conservation. In order to find out the scour resistance of gully soil with different active degree in dry and hot valley, this study is active. The surface soil of the trench bed and its catchment is more active and stable. Three different initial moisture contents of 0 ~ (50%) and 100% (100%) are set up. The methods of flume scour test and laboratory physical and chemical property analysis experiment are used. The physical and chemical properties of gully soil with different active degree, the characteristics of soil erosion resistance in different parts and the dynamic change characteristics of scour resistance coefficient of gully soil under different initial moisture content were studied. The influence factors of scour resistance of gully soil are analyzed. The results show that the crevasse activity changes from active, active to stable state. The physical and chemical properties of the gully soil are changed accordingly. The physical and chemical properties of the gully soil with different active degrees are as follows: the bulk density of soil, the content of sand particles, the angle of internal friction are the largest in the active gully and the smallest in the stable gully. The results showed that the stable gullies were active and active: soil total porosity, field water holding capacity, cohesion, silt content and clay content were opposite. The order of its content is active gully, active gully, stable gully. The sediment content of runoff decreased with the increase of time. The sediment content of the three types of gullies is active gullies, which are more stable than active gullies, and the main sediment production sites of different active gullies are not consistent. The main sediment yield of active and active gullies is gully head, and the main sediment yield part of stable gully is trench bed. (3) under the condition of different initial water content, the anti-scouring ability of soil is increased by power function. When the initial water content is 0%, the erosion resistance of soil is increased by power function. The erosion resistance of various parts of the gully development area is as follows: the trench bed head in the active gully catchment area, the trench head in the catchment area of the active trench bed, the stable gully trench bed catchment area, the initial water content being 50%, The erosion resistance of every part of the gully is as follows: active gully catchment area, trench bed catchment area, steady gully trench bed catchment area; When the initial water content is 100, the erosion resistance of every part is shown as active trench bed catchment, more active catchment area, and stable gully bed catchment area, which indicates that the gully in dry and hot valley area is under different water content. The active and active gully head, the soil body in the stable gully catchment area has the least scour resistance and is vulnerable to runoff erosion, so it is necessary to control the active gully head, the more active gully head, the more active gully head, the more active gully head, the more active gully head, Paying attention to the protection of stable gully catchment. 4) the influence factors of scour resistance of gully soil under different water content are different. The scouring resistance and shear strength of active gully soil (internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, etc.). The content of clay is positively correlated with various biodiversity indexes and negatively correlated with sand content, and is positively correlated with Simpson index, abundance and abundance of active gully soil, and negatively correlated with sand content. The scour resistance of stable gully was positively correlated with clay content, negatively correlated with field water holding rate, silt content, sand content and biodiversity index.
【学位授予单位】：四川农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.1

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