Research on Macropores Flow in Unsaturated Zone Soil of Slopes under Different Vegetation Community

To evaluate Macropores Flow in unsaturated zone Soil of natural Slopes under rainfall conditions, A dyeing tracing test with methylene blue was carried out based on retaining the original state of the slopes and simulating rainfall process. Combined with water breakthrough method and high-precision dyeing profile image, based on image processing, differential and regression analysis, distribution and influence factors of macropore flow in high coverage(90%) slope during the rainfall process were studied. The results show that: comparing with herbaceous vegetation community soil, the distribution range(dyeing coverage is at 46.18%-63.55%) of macropores flow in the profile of woody vegetation community soil is larger, the continuous degree is lower, the differentiation degree(dyeing route number is at 203-8 599) is higher, the staining patterns are more complex. Macropores flow patterns of 2D can reflect that of 3D. In the rainfall distribution process, competing with the interception effect of macropore in soils, slope orientation effect is tend to infiltrate vertically along the slopes(max dyeing coverage are at 63.55% and 59.67%). Roots size is not the only factor to control macropores scale(the mean pore sizes are at 1.23-2.03 mm and 1.34-2.23 mm). Aggregate particles themselves can also have root channels.