Characteristics Of Preferential Flow And Its Influencing Factors Study In Vegetated Slopes Soils

The term "landslide" describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock,soil,artificial fill,or a combination of these. There are many kinds of trigger for the occurrence of landslide, especially rainfall.The landslide induced by rainfall is called precipitation-induced landslide. The research about precipitation-induced landslide has focused on the relationship between rainfall and landslide, as well as water-rock interaction.but despised the process of the rainfall transfers into groundwater.In fact,the relationship between rainfall and landslide is indirect.Its conformation is controlled by the process of the rainfall transfers into groundwater,so it is highly necessary to intensive study the process.This paper takes two kinds of vegetated slopes soils for research objects. Dye infiltration experiments and water breakthrough curves methods are adopted respectively for research of morphological characteristics of preferential flow and distribution characteristics of soil macropores. By means of sample detection and field observation, the influencing factors of preferential flow were studied.In the end, the relationship between the characteristics of preferential flow and macropores properties has been discussed.Specific works are as follows:(1)Dye tracer selection. Before the beginning of field dye infiltration experiments, the comparative trial was done about dyeing effect of seven dye tracers(brilliant blue、brilliant green、methylene blue、rhodamine B、fluorescei、helianthine and methyl red). Dye tracer for field experiments was determined after careful consideration to all the factors was afforded.(2)Morphological characteristics of preferential flow. By means of dye infiltration methods, simulate rainfall occurred in a specific arca of two kinds of vegetated slopes. Characteristic parameters of staining images which is acquired through soil profile excavation were calculated by stereology method. Hereby.the similarities and differences of preferential flow in two kinds of vegetated slopes soils were compared.(3) Influencing factors of preferential flow. By means of sample detection and field survey, soil grain composition within0-40cm,organic content at regular depths, the root biomass of vegetation and distribution situation of wildlife passages can be determined.the change laws of them and morphological characteristics of preferential flow can illustrate the influencing factors of preferential flow. (4) Distribution characteristics of soil macropores and its relationship with morphological characteristics of preferential flow. According to water breakthrough curves,the distribution characteristics of soil macropores can be calculated by Poiseulle equation.Furthermore,the relationship between the characteristics of preferential flow and macropores properties has been discussed.