【作者】 牛健植；

【导师】 余新晓；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2003， 博士

【摘要】 本文所述内容是在国家重大基础规划项目课题(2002CB111502)、国家自然科学基金重点项目(39930130)及高等学校博士学科点专项科研基金(2000002009)的资助下完成的。主要针对研究区域土壤包气带根系层中水分快速运动的优先流展开研究，其目的在于系统分析优先流对径流过程的影响，为长江上游暗针叶林生态系统土壤水分运动规律研究及有效流域管理提供理论支持。 具体研究过程是以非饱和带土壤水分运动规律及地被物层、根系层生长发育特点和水分运动状况为基础，利用自制实验仪器，在研究区域四个不同演替阶段林地——幼龄林、中龄林、成熟林和过熟林开展室内土柱实验，并与野外实地示踪影像分析相结合，通过实验手段探讨研究区域土壤优先流运动过程，构建研究区域优先流分类体系，进行优先流发生判定及其特征分析等理论分析工作，以此为基础，建立融入弥散波的运动波模型(KDM优先流模型)，将此模型与实地实验检验分析，认定所构建的优先流模型实用性强、可靠程度较高。在具体分析研究区域优先流发生及运移规律之后，对研究区域优先流运移过程的影响因子进行论述分析，分析优先流对径流过程的影响。 采用雷诺数计算、示踪标定及示踪映像等方法对研究区域进行优先流发生判定，判定结果一致证明在所研究地区，有优先流现象发生。根据四个不同演替阶段林地中的优先流路径中的雷诺数值计算结果可知，贡嘎山高山生态系统中的优先流是处于层流及紊流之间的过渡流。 对研究区域优先流类型开展研究，研究结果表明幼龄林、中龄林及过熟林冰碛物土壤中的优先流类型是近乎连通的大孔隙流，成熟林坡积物土壤中的优先流类型是湿润峰占主导地位的非饱和重力流。 根据出流液的流量、通量及流速来分析土壤水流及优先流特征。研究发现研究区域内4个演替阶段的土壤水分运动的壤中流过程主要表现为优先流，而土壤中的基质部分，则表现为不动区域，并且一旦优先流路径形成，土壤将不再阻拦水入渗，导致随后的降雨入渗穿过前面已经湿润的、已经存在的优先路径。优先流路径是研究区域水分在土壤中运移的主要途径，只要降雨雨强不停止，水将始终沿着优先流路径向下运移。不同景观位置的优先流运移程度也不同，幼龄林和成熟林的优先流迁移程度低于中龄林和过熟林。在同一演替阶段的森林内的不同景观位置处，坡上位置处的优先流运移量较坡下位置的优先流迁移量多。 通过染色示踪及映像分析技术、室内土柱实验中出流液的流量、流速及通量数值分析可以判断分析出研究区域的土壤优先流具有环绕特征、快速穿透及非平衡特征；采用驻留力矩来分析穿透曲线(BTC)的平均穿透时间以及蔓延扩散和中文摘要拖尾程度，研究分析可知优先流的穿透曲线具有不对称性。 构建一个融有弥散因子的运动波模型(KDM优先流模型)，将KDM优先流模型用于成熟林坡积物土壤的土柱实验中，采用交叉模拟的方法计算出模型所需的参数，通过评价检验分析可知KDM优先流模型实用性较强。同时利用统计学分析方法对所构建的KDM优先流模型进一步验证，统计分析表明所构建的优先流模型可以较好地模拟水分在土柱中的运移过程，模型在低雨强条件下的拟合结果好于高雨强的拟合结果。利用构建的KDM优先流模型分析优先流对径流的影响，研究表明优先流的运移过程是运动波及弥散波共同作用的结果，运动波起主导作用，与前面分析水分在土壤中的运移过程主要是在优先流路径中运移相联系，可分析出优先流是土壤水分运移的主要通道，对流域径流形成及洪峰的发生都起着重要作用，也是地下径流的主要来源。 针对优先流的内外影响因子，具体分析了研究区域土壤孔隙、降雨规律、地被物层及根系层的特征。研究表明由于这些诱发因素存在，使贡嘎山高山生态系统具有优先流产生的可能。更多还原

【Abstract】 The dissertation researches on the preferential flow of the fast water movement in the root zone supported by National Basic Research Priorities Programme (2002CB111502), National Natural Science Fund (39930130) and Research Fund for the Doctoral Program of Higher Education (2000002009).The objectives of this research are to analyze effects of the preferential flow on runoff process systematically, to provide theoretic supports to the research on law of soil water movement of the dark coniferous ecosystem in the upper reach area of Yangtze River and the efficient watershed management.Based on the law of soil water movement of unsaturated zone, the growth characteristics and the water movement states of litters, moss and root, the detailed research discusses the movement of the preferential flow of the researched soil through experimental methods, sets up the classified system of the preferential flow of the study area and does the theoretic analyses, such as to discriminate the occurrence of the preferential flow and analyze its characteristics by carrying through the soil column experiment with homemade experimental apparatuses in four successive stages-young, middle-aged, mature and over mature and combining the dye-tracer analyzes of the field process, According to the research, the dissertation establishes the kinetic wave model with dispersion wave(KDM preferential flow model) and by inspecting and comparing this model with the field experiment, and finds the preferential flow model has good practicability and high credibility.After the inspection of the occurrence of the preferential flow and its movement law of the study area concretely, it discusses the influential factors of the movement of the preferential flow in the study area and analyzes the effects of the preferential flow on the runoff process. The conclusion can be drawn with the integration ofexperimental results.Aiming at the common used determinant method of the preferential flow, the dissertation gives a systematic discrimination to the occurrence of the preferential flow in the study area and proves that the preferential flow happens in that area through the analyzing. The Reynolds numerical calculation of the preferential flow path in the four different successive stages indicates that the preferential flow in Gongga mountain forest ecosystem is the transition flow between the laminar flow and turbulence flow.Through analyzing the types of the preferential flow in the study area, it indicates that the perceptible type of the preferential flow in young, mid-aged and over-mature is the approximate connected macropore flow and the one in the mature forest soil is unsaturated gravitational flow which is dominated by wetness front.By analyzing the characteristics movement of soil water flow and preferential flow through water discharge, flux and velocity, it shows that the flow in soil water movement in the researched four successive stages mainly exhibits preferential flow, and the matrix part of soil exhibits non-move area; once the preferential flow path comes into being, soil could not hinder the penetration of water, which causes the followed rain penetrating the front wet. The preferential flow path is the main route and water moves downward along the preferential flow till the stop of rainfall.The preferential flow of different landscape locations has different movement levels. The whole cumulative outflow of young forest is lower than that of mid-aged and over mature forests. In different landscape location of the same successive stage, the cumulative outflow on the hill is higher than that under the hill.It is judged that the preferential flow in the study area has surrounding characteristics through the dye and image analyzing technique. It is clear that the preferential flow in the study area has fast penetration and non-balance characteristics by numerical analysis of the water discharge, velocity and flux of soil column experiments. The BTC of preferential flow is asymmetric by analyzing time momentIt更多还原