【摘要】 文章利用ArcInfo的水文分析功能,从不同区域的三条典型泥石流沟的数字高程模型中提取出不同限值下的水系,然后研究了不同集水区面积下限导致的流域水系细节层次的变化,发现一级水系的数目和集水区面积下限成近似于反比的关系,而反比关系的比例系数只与流域面积有关。这种关系反映了泥石流流域的水系在空间尺度变换下的某种自相似性,也说明了泥石流流域在相当宽的空间尺度范围内一级子流域的物质活动能力是一定的。更多还原

【Abstract】 Drainages can show more complex structure at the smaller scale,which is the representation of the corresponding basin’s self-similarity.The detailed structures for different debris flow basins reflect their ability to transport material,which suggests that the small-scale structure plays an important role in the debris flow formation.Therefore,the paper focuses on the drainage hierarchical characteristic of debris flow basin,and two basin parameters(first-order stream number and area threshold) are used to examine this characteristic because the two are not affected by stream ordering methods and DEM errors.Three typical debris flow basins with different catchment area(Jiangjia,Longdong and Guxiang Ravine) were studied,which respectively located in three distinct regions.Using hydrological analysis tool in ArcInfo software the stream networks with different catchment area thresholds were extracted from these basins’ DEM and one set of first-order subbasin was identified.It is obvious that these subbasins occupy the whole basin’s fringe region where mass transportation starts.So this suggests that the subbasins play an important role in the initiation and material supply of debris flows.Another point is that the number of extracted first-order stream decreases rapidly with the area threshold increasing.It is found that the two parameters have close relation N=RAam have close relation,and exponent a equals to-1 and coefficient k only relates to the total basin area,namely for the same basin the product of first-order number with area threshold is constant in a wide scale range.The relationship may show that the ability of debris flow basin to transport material doesn’t change in so wide scale range.Further research will be paid more attention to the distinction of exponent a and coefficient k between debris-flow basin and non-debris-flow basin.更多还原