【作者】 史玉虎；

【导师】 张洪江；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2005， 博士

【摘要】 优先流是用于描述在多种环境条件下发生的非平衡流过程的术语,作为土壤水分一种特殊运动形式的优先流,是当今世界水文学研究的重点和难点问题之一。本文在大量查阅文献的基础上,对优先流的概念、分类、研究方法等进行了归纳,并以湖北省秭归县曲溪小流域为试验基地,采用挖土壤剖面将管流、剖面渗流引入流量计自计观测,并通过径流小区观测坡面地表径流、三角堰观测流域径流、数字雨量计观测天然降雨等方法,观测了天然降雨过程及其影响下优先流、坡面径流、渗流、地表径流的量和过程,分析了长江三峡花岗岩特定区域条件下优先流的产流机理、优先流路径、优先流的影响因素及优先流对地表径流过程的影响。取得的主要结论如下: （1）优先流是长江三峡花岗岩坡面的一种普遍现象,观测的管流雷诺数均大于10,土内渗流的雷诺数均小于10,根据北原曜的分类系统,以管流为主要形式的优先流运动不遵从达西定律。在该地区存在两种类型的土管,即地质性土管（原生性土管）和生物性土管（次生性土管）。土管在垂直方向上主要集中在土壤B层与C层的过渡带附近,呈聚集型分布。距地表的深度为0.8～1.0m,土管密度为5～7个/m。 （2）管流水文过程波形图基本相似,表现为明显的涨水、峰值和退水3个阶段,且涨水历时短,落水历时长。长江三峡花岗岩区的单个土管管流量为0.00036～0.17918m³,管流的峰值流量平均为120～25000cm³/h。管流受降雨量和降雨强度影响较大,同场降雨条件下管流量同降雨量线性相关显著,方程为: y=0.0035x-0.1105（R=0.9405） 优先流流量的波动与降雨强度的变化呈正相关关系,且在降雨过程中雨强的微小变化会导致管流水文波形的明显反映,尤其是阵雨的出现,会使缓慢下降的管流流量水文波形下降的更为缓慢或转而产生小幅度的回升。 （3）管流占剖面渗流总量的比值为8.7%～22.11%,场降雨过程中,管流量和剖面渗流量呈线性正相关关系,一般关系式为: y=30.58x+7.42×10^-3（20020528号降雨,r=0.812） （4）同等降雨及下垫面条件下,管流量和对应的坡面地表径流量呈线性正相关更多还原

【Abstract】 Preferential flow is used for describing term of non-equilibrium process that takes place under many kinds of environmental condition, being as a kind of special movement form of soil moisture, the preferential flow is focal point and one of difficult point problems that the hydrology is studied in current world. This text has been summed up to concept, classification, research approach of preferential flow, etc. on the basis of a great amount of consultable literatures. Regarding Quxi small watershed of Zigui County in Hubei province as trial base, pipe flow and soil infiltration flow to flow meter have been introduced and observed by itself through the soil section, the preferential flow, slope surface flow, soil infiltration flow, and the total surface flow of watershed have been observed under observed natural rain process and its influence by the method of observing slope surface flow、 the total surface flow、 natural rain through flow district、triangular weir and digital rain meter; flow theory、 path, influence factor of preferential flow and the influence of preferential flow to the process of surface runoff are analyzed under the specific regional condition in granite region within Three-Gorges of Yangtze River. The main conclusions achieved are as follows:（1） Preferential flow is a common phenomenon in the granite region of the Three Gorges in the Yangtze River. The observed Renault quantity of pipe flow is averagely bigger than 10, on the other hand, the observed Renault quantity of soil infiltration flow is averagely smaller than 10. According to the classification system of Kitahara Hikalu, the preferential flow predominated to the pipe flow as a main type can not follow to Darcy Law. Two kinds of soil pipe exist in the granite region of the Three-Gorges in the Yangtze River, which are the biological pipes formed by dead plant roots and the geological pipesformed by soil cracks. The result of field observation shows that the soil pipes concentrate mainly nearby the transitional zone forming distribution with assembling type between weathering of granite layer and the semi-weathering of granite layer, where is about deep 1.2 -1.6 m under the ground surface, and density of the soil type is about 5-7 pieces per meter.（2） Hydrology wave shape of pipe flow is similar basically, shown obviously 3 stages that are rising, peak value and retreating, and it lasts short to rise as well as lasts long to fall. In the granite region of Three Gorges in Yangtze River, the pipe flow’s quantity of single soil pipe is about 0.00036-0.17918 m3, the average peak quantity is about 120-25000 cm3/h. The pipe flow is significantly influenced by precipitation and rainfall intensity, meanwhile at the same condition of rainfall, linear interrelation between the quantity of pipe flow and rainfall is obvious, the equation is:y= 0.0035x-0.1105 （R=0.9405）.Quantity wave of the preferential flow is positively related to changes of the rainfall intensity, moreover, the pipe flow is sensitive to the micro-changes of rainfall during the rainfall period, and micro-change of intensity of rainfall will be distinctly reflected in pipe flow’s hydrological graph, especially, it may make pipe flow’s hydrological graph downtrend, or cause small bounce.（3） The ratio of the total amount of the sectional influent to the pipe flow is 8.70%-22.11%, among the rainfall process, the quantity of the pipe flow is linear positively interrelated to the relation of total amount of soil infiltration flow, the general relational equation is:y= 30.58x +7.42 x10^-3 （the rainfall NO.20020528, R=0.812）（4） Under the condition of equal rainfall and ground, the quantity of pipe flow is linear positively interrelated to relation to corresponding surface runoff in slope, the general equation is:y = 0.7761x+ 0.0379 （R=0.9107）（5） The percentage ratio of the quantity of pipe flow covering total runoff quantity ofthe watershed is 0.53%².31%. During the raining process, the total quantity of pipe flow and total quantity of the runoff in the watershed assumes更多还原