| 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...
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