基于DEM的黄土高原小流域主沟道汇流累积量沿程变化模式

DEM-based research on change patterns of flow accumulation of main channel of small watersheds in Loess Plateau

文章以30m的ASTER GDEM(Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model)为数据源,利用ArcGIS水文分析工具提取了黄土高原9个不同水土保持分区典型小流域的沿程沟道网络,绘制了小流域主沟道汇流量的沿程变化曲线,并对其模式及地学意义进行研究。结果表明,沿程变化模式分为线性模式和台阶模式。线性模式小流域的岩土层一般分布较均匀,其线性函数斜率越小,子流域汇流面积或地形起伏越小,反之则越大;其线性函数截距越小,一般分布在年均降雨量越大的区域,反之,则分布在年均降雨量越少的区域。台阶模式小流域一般分布在岩土层不均匀的区域。该研究是对黄土高原小流域地貌定量研究理论和方法的一种探索,对进一步研究黄土高原小流域地貌演化机理等具有参考意义。

Based on the 30 m Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model(ASTER GDEM),the hydrological analysis tools of the ArcGIS are used to extract the channel networks of typical small watersheds in nine zones of conservation of soil and water in the Loess Plateau.The change curves of the main channel flow accumulation in the small watersheds are drawn,and its models and geological significance are studied.The results show that the change patterns of flow accumulation along the main channel can be divided into linear model and stepped model.In the small watersheds with linear model,the distribution of rocks and soil layers is relatively homogeneous.If the slope of the linear function is small,the confluence area of the sub-stream is small or topographic relief is small,and vice versa.If the intercept of linear function is small,the small watersheds always lie in areas with high annual mean rainfall,and vice versa,they lie in areas with low annual mean rainfall.The small watersheds with stepped model lie in regions with uneven rocks and soil layers.The research results are useful for quantitative theory and methodological research of the geomorphology of small watersheds in the Loess Plateau,and have a reference value for the further research of the geomorphic evolution mechanism of small watersheds in the Loess Plateau.