祁连山东段金强河河谷高寒草地土壤的水文特征

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

祁连山东段高寒草地土壤水文效应对该区域陆面水文过程、水文循环、石羊河水资源和生态环境维持等作用巨大。因此,深入开展高寒草地土壤水文效应研究对深入了解和认识高寒地区土壤水文过程和陆面水文过程有重要意义。为此,本研究以祁连山东段金强河河谷高寒草地为对象,分析了土壤含水量、持水特征、入渗速率和草地蒸散等土壤水文特征和变化规律。结果表明:河谷山地阳坡和河谷山地阴坡下部高寒草地田间持水量、毛管持水量和饱和持水量随土层加深先增大后减小,河谷水平阶地和山地阴坡上部高寒草地土壤持水量随土层加深逐渐增大;河谷0-30 cm土层高寒草地田间持水量和毛管持水量均为阴坡上部>阳坡下部>阴坡下部>阳坡上部>水平阶地,饱和持水量表现为阴坡上部>阳坡下部>阳坡上部>阴坡下部>水平阶地。高寒草地土壤初渗透率最小,渗透性随着渗透时间的增加土壤渗透速率不断增大,当渗透达到稳定状时土壤渗透速率最大。河谷高寒草地0-30 cm土层土壤含水量为阴坡下部>阴坡上部>阳坡下部>水平阶地>阳坡上部。河谷高寒草地在6月-9月的日均蒸散量为2.429 mm·d^-1,蒸散总量为293.254 mm。可见,研究区河谷地形对高寒草地土壤水文特征有显著的影响,因此对祁连山东段高寒区水资源合理管理与利用过程中要综合考虑地形与土壤水文特征之间的关系。

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.