| 题名 | 坡地边沟水土保持机理研究 |
| 作者 | 蔡雄飞 |
| 学位类别 | 博士 |
| 答辩日期 | 2012-05-25 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 王玉宽 |
| 关键词 | 坡地边沟 坡耕地 水土保持 机理 |
| 其他题名 | The Study on Soil and Water Conservation Mechanism of Slope Farmland Side Ditch |
| 学位专业 | 自然地理学 |
| 中文摘要 | 坡面水系工程是中国南方地区传统的水土保持工程措施，坡地边沟是坡面水系工程的重要组成部分，在防治水土流失，保护坡耕地中起着关键作用。由于坡地边沟规格和形状随坡地条件、耕作制度、耕作习惯、区域气候等不同而复杂多样，其保水保土功能及作用机理至今仍不清楚。这也是坡面土壤侵蚀和坡面水文过程研究中无法回避的问题。在对典型区域坡地边沟实地调查的基础上，通过基于人工模拟降雨的大田模拟试验、室内人工模拟径流的模拟试验等方法探讨坡地边沟水土保持机理，旨在拓展明渠水流研究范围，探讨具有单边汇流的地边沟水沙输移机理的知识，同时为丘陵区坡耕地的治理与保护提供理论依据。得出如下主要结论： （1）土壤物理性质和地边沟沟底坡度是影响地边沟保水效益的主要因素。地边沟保水效益的区域差异显著，当沟底坡度为0°或1°时，地边沟保水率在14.8%-36.72%之间，当沟底坡度为3°时，地边沟保水率在6.4%-25%之间。 （2）当坡度较小（1°或0°时），沟长较长时（大于3m），沟中径流流速呈增大、减小的周期性变化趋势。不同条件下径流雷诺数随径流含沙量的增大而减小、随雨强的增大而增大、随沟底坡度的增而增大；从沟头开始，雷洛数与沟长（径流流量）呈线性显著相关关系， R2≥0.84。 （3）地边沟沟底坡度、输入径流含沙量以及输入径流量是影响地边沟中泥沙沉积的主要因素。同坡度，不同雨强、含沙量条件下，输入泥沙总量和沟中泥沙沉积总量不同，但泥沙沉积率几乎不变。当沟底坡度从0°增大到1°、3°时，地边沟中泥沙沉积率从78%减小到55%、13%。沟中泥沙沉积量与沟底坡度呈负相关，与坡面来沙量呈正相关关系。可用以下模型表达其相互关系： Y=-1614.13X1 + 222793.3X2 + 21.2X3 - 1614.1 式中Y 为地边沟中泥沙沉积总量（g），X1 为地边沟沟底坡度（°），X2 输入径流含沙量(g/ml)， X3 输入径流流量（ml/s）。 （4）不同沟底坡度条件下，随着输入径流流量的增大，输入径流和输出径流的平均含沙量变化复杂。当坡度为0°或1°时，输出泥沙主要以悬移质为主，所以输出含沙量逐渐减小。当坡度为3°时，随着沟中径流流量的增大，水动力逐渐增强，沟中径流对已沉积的泥沙形成再次搬运，输出径流含沙量呈逐渐增大的变化趋势。 （5）同坡度，不同来水量和来沙量条件下，输入泥沙总量和地边沟中沉沙总量均不同，但是沉积泥沙的分布特征相似。当坡度为0°或1°时，泥沙沉积呈现周期性的增减循环变化，当坡度增大后，沟中沉积量减小，多数仅地边沟源头形成一个沉积峰值。 （6）当沟底坡度为0°或1°时，沟中泥沙与输出（地边沟出口）径流泥沙颗粒组成变化显著。沟中泥沙极细砂、细砂、中砂、粗砂增大，细砂富集。输出径流泥沙粘粒，细粉粒增大，细粉粒富集。当沟底坡度增大到3°时，沟中泥沙与输出径流泥沙颗粒组成变化较小。输出径流泥沙粉粒相对减小，砂粒相对增大，而沟中泥沙变化与此相反。 |
| 英文摘要 | The slope water system projects are traditional project measures of water and soil conservation in southern China, the slope farmland side ditch（SFSD）is an important component part of slope water system projects, which plays a key role in slope farmland protection and treatment. However, SFSD which widely used in production and close contact with the sloping farmland, although with a long history of practical application, the size and shape change with the sloping farmland conditions, farming systems, farming practices, regional climate, the function and mechanism of water and soil conservation is still unclear. this is the problem that we can not avoid in study on the processes of slope soil erosion and hydrology.The experiments of field artificial rainfall simulation and indoor artificial runoff simulation were done based on field work in typical regions, which not only can expand the scope of open-channel flow, but also can rich the water and sediment transport mechanism of open-channel flow which is unilateral confluence, while provide a theoretical basis for management and protection of the hilly area.The results show that: (1) Soil physical properties and Ditch Slope of the SFSD are major factors affecting water conservation quantity of SFSD, and which is different obviously between areas. When the bottom slope of the SFSD is 0° or 1°, water retaining rate is between 14.8% and 36.72%, and when the bottom slope of the SFSD is 3°, water retaining rate is between 6.4% and 25%. (2) In case that the slope was 0°or 1°, an increasing and decreasing periodic cycle appeared of the flow velocity in the SFSD. The Reynolds number decreases increases with the increasing runoff sediment concentration, and increases with the increasing rainfall intensities and the bottom slope of the SFSD. There exists a linear correlation between the Reynolds Number and the ditch length ( R2≥0.84). (3) The bottom slope of the SFSD, the input sedimentat concentration and the input variability of runoff are the main factors affecting sediment deposition rate. With increasing slope from 0 ° to 1 °and 3 °, the sediment deposition rate decreased from 78% to 55% and 13%, with the variation being less than 5%. There is a positively correlation between sediment deposition and input sedimentat concentration, a negative correlation between between sediment deposition and the bottom slope of the SFSD. A model could express their mutual relations: Y=-1614.13X1 + 222793.3X2 + 21.2X3 - 1614.1 Y is the total sedimentation depositied in SFSD (g), X1 is the bottom slope of the SFSD (° ), X2 is the input sediment concentration (g/ml), X3 is the input runoff rate (ml/s). (4) The input runoff and output runoff rate change is complex under different slope of the SFSD. When the slope is 0 ° or 1 °, the output sediment is mainly suspended load, and output sediment concentration decreases gradually. When the slope is 3 °, with the increase of runoff rate in the ditch, the water power gradually increased, and the deposited sediment was transported out of the SFSD again, and the output sediment concentration was gradually increasing. (5) As for the same slope, different rainfall intensities and sediment concentrations, differences were recognized in total incoming sediment and sediment production in the testing ditch, while almost no difference was found in the distribution characteristics of sediment production. In case that the slope was 0°or 1°, an increasing and decreasing periodic cycle appeared, with increasing slope to 3°, the sediment deposition decreased. In most cases there appeared a peak near the source of the testing ditch. (6) When the ditch slope from 0 ° or 1 °, the particle composition of sediment in the SFSD and output (Mizoguchi) runoff and sediment changes significantly.the very fine sand, fine sand, medium sand, coarse sand in the SFSD increased, clay, fine silt increases, fine silt of deposited soil in ditches decreased significantly, and very fine sand increased significantly, but the case is opposite to fine silt and very fine sand in transported soil. |
| 语种 | 中文 |
| 公开日期 | 2013-01-15 |
| 内容类型 | 学位论文 |
| 源URL | [http://192.168.143.20:8080/handle/131551/4809]  |
| 专题 | 成都山地灾害与环境研究所_山区发展研究中心 |
| 推荐引用方式 GB/T 7714 | 蔡雄飞. 坡地边沟水土保持机理研究[D]. 北京. 中国科学院研究生院. 2012. |
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