云南蒋家沟流域泥石流沟谷演变的非线性特征

蒋家沟是我国西南山区一条典型的暴雨泥石流沟，位于云南省东北部金沙江支流小江河谷的右岸。主沟长13.9km，流域面积48.6km^2，平均纵坡比降16.02%，流域内有4级支沟。据统计，沟谷长度大于0.50km的各级泥石支沟有26条，其中主沟1条（即蒋家沟）,另含Ⅰ级支沟6条，Ⅱ，Ⅲ，Ⅳ级支沟各2，7和10。蒋家沟流域内各级泥石流支沟尽管在形态上具有自相似性，但在空间分布上则具有均一性，从各支沟的数目、密度和流域面积看，均表明由沟口至沟源（尾）有逐渐增强的趋势，且主要集中在门前、多照两沟内。对蒋家沟及流域内各泥石流支沟的沟谷形态分析显示，各支沟的流域面积、沟道坡降及长度均存在明显的分形特征，它们与沟道数目之间有良好的非线性关系。这种非线性关系一 定程度上揭示了这些泥石流沟谷演变的非均匀性和自相似性。

DEBRIS FLOW GULLY DISTRIBUTION AND ITS NONLINEAR PROPERTYOF EVOLUTION IN JIANGJIAGOU AREA,YUNNAN PROVINCE

Jiangjia Ravine is a famous rainstorm debris flow gully in the southwest mountain area of China.It is located on the right bank of Xiaojiang River which a tributary of Jinsha River northwest Yunnan Province.Jiangjia Ravine's main gully length is 13.9 kilometers,with the drainage area being 48.6 square kilometers and average gully ratio of slope 16.02%.There are 4 grading tributary gullies in Jiangjiagou area.According to statistical data,there are 26 more than 0.5 kilometer long gullies of different tributary grades.Of these,one is the major gully,6 the first grading gullies,2 the second grading,7 the third grading and 10 the fourth.The different grading gullies of debris flow have a self similarity in shape,but they are not uniform in spatial distribution.The number,density and drainage area of the debris flow gullies have a trend of increase,which are mainly concentrated in Menqian and Duozhao gullies.The 26 detris flow gullies in the Jiangjiagou gully area occurred in the \{13.9\} km long valley.Each gully has its own obvious fractal property in terms of drainage area,gully length and slop ration,which are non linearly correlated with the number of gullies.The non linear relationship may indicate the development of non uniformity and self similarity of debris flow gullies.Although the scale of each gully is different,the gullies are formed through retrogressive erosions.