| چکیده انگلیسی مقاله |
Soil preferential flow, as one of the most common forms about the movement of soil water, is an important process of water downward leakage. The rock and soil is in mosaic pattern in the Karst Rocky Desertification Area. The development of preferential flow in soil affected by rock boundary of outcrop rock may be different from that in the non karst area. The aims of this study are to: 1) analyze the distribution characteristics of soil preferential flow pathways under the influence of different types of rock boundaries; 2) the dyeing area characteristics of soil preferential flow affected by rock boundaries with different types; 3) the effect of rock boundaries on the development of preferential flow in soils. To achieve the above goals, several text sites with five typical rock boundary types were selected in an area with severe rocky desertification in the Guizhou Province, China. A dye tracing method, one of the most commonly used methods to research preferential flow, combined with digital image processing technique were applied in this study. Results indicated that: the rock-soil interface flow is the most important form of soil preferential flow in the karst area. The dyeing area ratio of preferential flow changed from 0.12 to 0.48 in rock-soil profiles, from 0.06 to 0.37 in soil profiles, while between 0.02 and 0.16 in rock profiles. The rock profiles are the smallest in both dyeing area ratio and variation ranges of preferential flow compared with soil and rock-soil profiles. The soil preferential flow mainly occurs at the soil depth of 0-20 cm under different rock boundaries. The pathway of preferential flow is mainly the rock interface on both sides, which can pass through the yellow clay soil with poor permeability. However, the dyed part of rock interface can reach the soil depth of more than 50 cm. The flow in rock-soil interface affected by different rock boundaries is the main form of preferential flow in the karst rocky desertification area. It can flow to the bottom of soil layer by passing through the layer with poor permeability, which is an important inner-factor of water leakage in the karst rocky desertification area. |
