The Research On Characteristic Of Preferential Flow In The Typical Slope Around The Reservoir Area In Danjiangkou

Economy of danjiangkou reservoir is taking agriculture as foundation, residues of pesticides and fertilizer in the soil can migrate to groundwater along the preferred path in the soil, preferential flow along the preferred path is not only resulting to the loss of fertilizers and pesticides, but also resulting to pollution of surface water and groundwater and soil erosion.There are few studies about law of motion preferential flow for the slope of danjiangkou reservoir,revealing that formation and mechanism of preferential flow about the reservoir area and protecting of water quality and safety in the reservoir area are require problems to be solved, This paper sets slope around the Danjiangkou reservoir located in xingdoupo village of xijiadian town as study area, and selects5typical location in whole slope to carry on dyeing experiments, and then the stained images are obtained. We analyze the quantity vertical variation of soil staining path and the characteristics of path width distribution and the preferential flow type around the reservoir area, soil physical and chemical properties and soil vertical infiltration are analyzed as well, we study the influences on soil physical and chemical properties and soil vertical infiltration contrast to morphological variation of preferential flow type and type of preferential flow. The main work and conclusions in this paper included:(1) Preferential flow phenomena from the bottom to the top of the slope happens frequently,In the ecological protection of soil and water conservation district,the migration distance of matrix flow is the farthest in the range soil depth from0cm to15cm, followed by the migration range from0cm to10cm in the reservoir buffer zone, which deeper than the Migration range from0cm to5cm in the Sesame Place,then the Migration range that from0cm to4cm of the soil surface in the definition in Water Conservation Forest is shorter than whicn in the Sesame Place, and then orangery has the shortest Migration rang that from0cm to2cm in the five test areas of entire slop. Migration depth of preferential flow is from3times to15times than the matrix flow in the whole slope.we find tha there are relationship moisture content of the soil and plant roots which distribution at soil surface through the excavation process.Following The higher of the surface soil moisture and the more small and intensive of the soil root system,and then the range of the matrix flow transport is more deeper.This paper chose the Stained path width that<20mm and>200mm as standard, Subsurface flow could be classified as five types:homogeneous matrix flow, macropore flow with mixed interaction, macropore flow with high interaction,heterogeneity figering flow and macropore flow with low interaction,preferential flow include thefigering flow and macropore flow, emergence and development of preferential flow in the whole slope is mainly heterogeneity figering flow,which in depth of the soil generally from7cm to35cm.Based on the grade distribution of stained path width to determine the type of Subsurface flow, the results of this method is more realistic and accurate than using the stained area of the semi-quantitative or intuitive to analyze the images of staining profiles obtained results.(2) The differences of staining area ratio directly reflects the characteristics of morphological changes of preferential flow between the different sampling plots within the soil profile. For each different plot of the shore reservoir, with the deepening of the stained area, the corresponding soil staining area ratio also changes,both showed significant logistic (the logistic) curve relationship which illustrate the fact that matrix flow and preferential flow happen together and show some certain correlation.(3) We identify the relationship between the process of the different soil cumulative infiltration with the diachronic change and the organic matter content and texture referring to the organic matter content and different soil texture test and analysis results of various sampling sites. With the increasing of the organic matter content, cumulative infiltration correspondingly increased, with the decreasing of the clay content, cumulative infiltration basic increased. Organic matter content and clay content play mutual inhibition role of the cumulative infiltration; The infiltration model of Kostiakov and infiltration equation of Philip can well reflect the changes in the cumulative infiltration corresponding to infiltration time change, the passage of humid peak can be explain well by infiltration equation of Philip; As time goes by, the humid peak onward rate shows a reduced trend for the most of soil with the increasing in clay content while shows a increased trend with the increasing in organic matter content, we can draw a conclusion that organic matter content and clay content play inhibition role of soil passage velocity of the humid peak.