攀枝花泥石流沟谷形态的非线性特征

NONLINEAR PROPERTIES OF DEBRIS FLOW GULLY FORM IN PANZHIHUA

攀枝花市大部分地区属泥石流重度危险区,所辖区县历史上多次受泥石流危害,现在仍有许多城镇、工矿、电站和交通设施受泥石流威胁。区内泥石流沟主要分布在断裂发育、岩层风化强烈、暴雨频发的安宁河、金沙江和雅砻江河谷地带。通过对区内近200条泥石流沟发育状况统计分析发现,泥石流沟沟床比降、流域面积、主沟长度、形态数和相对高度在空间分布上具非线性的分形特征,与对应的泥石流沟条数具良好的非线性相关关系,表明泥石流系统的演化具自相似性。其中沟床比降和流域面积的分维值最小,对泥石流沟的形成、演变控制最为显著。这也在一定程度上揭示了这些泥石流沟谷形态演变的非均匀性和自相似性。

Most districts of Panzhihua are high danger areas of debris flow. Those counties dominated by Panzhihua were formerly endangered by debris flow. Till now, many towns, mine areas, power plants and traffic establishment are threatened by debris flow. The debris flow gullies in this area are distributed in zones of Annin, Jingsha and Yalong rivers, which have the characteristics of developed fault, strong rock weathering and frequent rainstorms. Based on the statistics of development conditions of about 200 debris flow gullies, The authors found that the gully ratio of slop, drainage area, main gully length, gully form factor and the relative altitude have the nonlinear properties on the spatial distribution, which also have a good nonlinear correlation with corresponding debris flow gullieg. It is shown that the evolvement of debris flow has self-similarity. Among these factors given above, the values of the gully ratio of slops and the drainage area are the least. This illuminates that the gully ratio of slops and the drainage area could control the form and progress of debris flow. These phenomena also reveal the nonuniformity and self-similarity of debris flow gullies development on certain degree.