The Study on Soil Hydrology Course in High-cold RegionTwo Small Basins in the Source Region of Yellow River for Instance

Soil, vegetation and rainfall are the main factors controlled the watershed hydrological process. In order to examine the effects of high-cold vegetation on the soil hydrologic process in high-cold area of the source region of Yellow River, two small basins (Kurewaermna River and Natong River catchenment) with different degenerate degrees were selected as paired catchments. The self-made artificial rainfall device was used for rainfall simulation. Based on the field rainfall-runoff examination under different plant types, coverage degrees, the rainfall- runoff process, sediment yields, soil infiltration and soil water content changes are measured and analyzed. The results show that the process of runoff and sediment yield were power function (y = ax^b ) distribution in alpine meadow with different coverage, when coverage varying from high to low, the parameter a decreasing, and b increasing, while were better in exponential function (y = ae^bx) distribution in black soil with coverage below 5%. Under the same rainfall intensity, the higher is meadow coverage the lower is runoff amount, the vegetation is positive correlation to duration, i.e. runoff duration is prolonging with the coverage increasing, which indicates that increasing vegetation coverage is an important measure to alleviate soil and water loss and reduce runoff on slope land. The results also show that the water content variety in the vertical section of the soil with different surface feature units, vegetation types and slope gradients has great difference during a rainfall course, the soil moisture variety in 10 ~ 25 cm is more evident than that in 0 ~ 10 cm. The hydraulic erosion of the black soil type (coverage below 5%) is more serious than that with higher coverage and the water loss and soil erosion is fast.