黑水河干旱河谷沿程土壤物理参数梯度变化特征研究

Study on Gradient Variation of Physical Parameters of Soil along the Drought Valley of Heishui River

横断山区干旱河谷是具有典型的旱季和雨季的特殊气候特征的区域，本区域土壤退化和荒漠化极大制约了区域农业的发展。本文研究了金沙江干热河谷区支流黑水河从源头到河口未扰动土壤的物理参数变化特征。结果表明，沿河土壤物理呈现不同变化趋势，砾石在中游部分河段和河口段高，而〉5mm团聚体的变化则相反；5～1mm的团聚体变化不大；〈1mm团聚体河口和源头段高于其余地段；土壤容重沿程增大，非饱和导水率源头地段土壤最高。本研究初步揭示了干旱河谷土壤不均匀，不同水热条件及其组合可能对退化程度有至关重要的影响。这表明横断山区不同的干旱河谷地段土壤和植被退化途径、退化特征和退化过程不同，开发和治理途径与方式也应当不同。

The drought valley of Jinsha River in Hengduan Mountains is eharaeterized with both dry season and monsoon, where the development of local agriculture is restricted by soil degradation and desertifieatian. This paper studies on gradient variation of physical parameters of undisturbed soil along the whole drought valley of Heishui River, one of the branches of Jinsha River. The results showed that the physieal properties of the soil have different variation style along the river. Gravel content of the soll is higher at middle reach and debouehure. While the eantent of aggregate with size of 5mm or more is lower at middle reach and debouehure, and the eantent of aggregate with size less than 1 mm is higher at debouehure and headstream. The bulk density of the soil gets higher along the stream and the headstream soil has the lowest unsaturated hydraulic conductivity. The study shows that nonuniformity, different hydrothermal condition and their combination play a vital role in the degradation process. Therefore, different measures should be taken for ecological restoration according to factual conditions in different degradation of soil and vegetation.