Soil hydrological characteristics of alpine grasslands in the Jinqiang River Valley in Eastern Qilian Mountains

The soil hydrological effect of the alpine grassland in the eastern Qilian Mountains plays an important role in the regional land hydrological process, hydrological cycle, shiyang river resources and ecological environment maintenance. Therefore, it is of great significance to study the soil hydrologic effect of alpine grassland in order to understand the soil hydrologic process in alpine region. In this study, We analyzed characteristics of soil water holding capacity, ariation of evapotranspiration, permeability and soil water content change, etc. The results showed that the field water holding capacity, capillary water holding capacity and saturated water holding capacity of the sunny slope and the lower of sunny slope in mountain valley increased first and then decreased with the deepening of soil layer, while the soil holding capacity of valley terrace and the upper of shady slope in mountain valley increased gradually with the deepening of soil layer. The field water holding capacity and capillary water holding capacity in the 0 – 30 cm soil layer were upper of shady slope > lower of sunny slope > lower of shady slope > upper of sunny slope > valley terrace. The saturated water holding capacity were upper of shady slope > lower of sunny slope > upper of sunny slope > lower of shady slope > valley terrace. The initial infiltration rate of alpine meadow soil was the minimum, and the permeability increased with the increase of infiltration time. When the permeability reached a stable state, the permeability rate of soil was the maximum. The soil mass water content in the 0 – 30 cm layer of alpine grassland was lower of shady slope > upper of shady slope > lower of sunny slope > valley terrace > upper of sunny slope. During the period from June to September, the average daily evapotranspiration of alpine grassland in the valley was 2.429 mm·d^–1, and the total evapotranspiration was 293.254 mm. The evapotranspiration of alpine grassland was in July > in August > in September and June, and increased first and then decreased with the change of seasonal temperature. It can be seen that the valley topography in the study area had a significant impact on the soil hydrological characteristics of alpine grassland. Thus, the relationship between topography and soil hydrological characteristics should be considered comprehensively in the rational management and utilization of water resources in the high and cold region of the eastern Qilian Mountains.