紫色丘陵区小流域侵蚀沉积断面构型及土壤颗粒分形特征

Erosion-Sediment Sections and Soil Particles Fractal Dimensions of Small Watershed in Purple Hilly Area

土壤侵蚀沉积是地球物质循环的重要环节,但人为因素使之加剧并引起许多生态环境问题。以四川紫色丘陵区小流域为例,根据地形部位及土壤性状划分出侵蚀沉积纵横断面,分析其侵蚀沉积特征,并采集土壤样品研究其颗粒组成和分形维数特征。结果表明:侵蚀沉积纵横断面不同地形部位侵蚀沉积特征明显不同,可分冲刷剥蚀、搬运扩散和沉积掩埋3种类型并连为侵蚀沉积链;侵蚀沉积纵横断面的划分对土壤侵蚀与沉积的认识更全面,整体性更强。研究区颗粒组成特别是粘粒含量明显地体现出侵蚀沉积的差异,分形维数综合体现出明显地随高度降低粗粒物质减少、细粒物质增加的趋势。

Natural soil erosion and sediment are important parts of geologic cycle, but they have been accelerated by human activities and many eco-environmental problems arised. In a small watershed of purple hilly area, Sichuan province, the erosion-sediment sections were marked out basing on differences of topographic and soil features, and the characteristics of soils particle component as well as its fractal dimensions were also studied on the routine analyzing results. The results showed that: the erosion-sediment features of different spots on erosion-sediment trans/vertical section are different distinctively. Types of washing and denudation, moving, and sediment and burying, which components an erosion-sediment catena, can be distinguished. Sediment is main process on erosion-sediment vertical section. We can get more entire and whole understanding of erosion-sediment through dividing erosion-sediment section types. Particle components, especially clay contents, significantly embodied the differences of erosion-sediment. The trend of sand decreasing and clay increasing with altitude reduce is embodied synthetically through particle fractal dimension.