STUDY OF SOIL PREFERENTIAL FLOW IN THE DARK CONIFEROUS FOREST OF GONGGA MOUNTAIN, CHINA
贡嘎山暗针叶林土壤优先流形成因素的初步研究

Background and Aims Preferential flow is the physical phenomenon of rapid transport of water and solutes in soil. It occurs in most soils and determines field-scale transport of contaminants in soils,thereby contributing to groundwater pollution. Methods Research on preferential flow involves studying the mechanism of soil water movement and can answer key questions that could not be explained by Darcy's law and Convective-Diffusive Equation in early hydrological research. Experimental or technological analyses are difficult because this movement is not detected easily. Preferential flow increases the difficulty and complexity of the research due to non-equilibrium,regional characteristics and the involvement of many influencing factors. To date,the mechanism of the movement of preferential flow has not been properly defined. This study involved detailed research on the influencing factors of preferential flow,using a soil column experiment in combination with dye-tracer analyzes in the root zone of the dark coniferous ecosystem in the upper drainage of the Yangtze River. Factors examined included rainfall processes,growth characteristics and water movement states of litter,moss,roots and soil. Key Results The soil of the research area is porous with large pores,and rainfall is low in amount and intensity and long-lasting. The soil also has thick litter and moss and is rich in roots. Therefore,the Gongga Mountain ecosystem may have preferential flow. Water transport has opened up preferential flow pathways along soil pores and root channels,forming a water channel in litter,moss and soil. Conclusions Soil will be transported continuously along these channels with longtime rainfall.