青藏高原地区水土流失时空分异特征

Temporal and Spatial Distribution of Soil Loss on Tibet-Qing Plateau

青藏高原的自然地理环境十分独特却也非常脆弱,水土流失的潜在危害性大。在全球变化和西部大开发的背景下,研究青藏高原水土流失规律具有重要意义。从自然地理条件出发,总结了青藏高原水土流失具有侵蚀类型多样,区域分异明显,人为作用较弱但潜在危害性大等特点。通过分析青藏高原河流泥沙资料,对土壤侵蚀强度的区域分异和水土流失的年内变化进行了初步研究。可以看出区内输沙模数的区域差异较大,输沙模数的大小主要决定于降雨条件和地表覆盖(包括地表物质组成和植被覆盖)。输沙模数的分布也一定程度上反映了土壤侵蚀强度的区域差异。青藏高原地区水土流失在一年中较为集中,7、8月份输沙量占全年的65%左右,6～9月份输沙量占全年的90%左右。由于夏季冰雪融水作用,径流泥沙可比降雨提前到达峰值。

The natural condition of Tibet-Qing Plateau is unique but especially fragile. Thus, the potential hazards of soil loss may be greater than other place. Under the background of global change and West Development Strategy, the research on the soil loss on Tibet-Qing Plateau is of great importance. According to its natural condition, three main characters were summarized: diversity in erosion type, unevenly-distributed erosion intensity, weakness but great potential hazards in man-made erosion. Analyzed the temporal and spatial distribution of soil loss with the sediment yield date of river. It was showed that the distribution of the sediment modulus was greatly uneven and was mainly determined by rainfall and land cover. To a certain extent, the soil erosion intensity could be demonstrated by the sediment modulus. The sediment yield was highly concentrated in July and August, accounting for 65%. Due to the thaw of snow and ice in early summer, the peaks of runoff and sediment yield could precede that of rainfall.