怒江东月各特大泥石流流域几何形态学特征

Basin morphology characteristics of the giant debris flow in the Dongyuege gully near the Nujiang River

怒江支流东月各沟于2010年8月18日凌晨暴发灾难性泥石流,其规模巨大且远程运移超过8 km。为了探究其发生机理,从流域几何形态学特征的角度出发,对东月各泥石流地形条件进行量化研究。在野外调查基础上,对泥石流运移路径纵坡进行1∶1 000比例现场测量,使用1∶10 000比例尺摄影测量数字线划地形图和Arc GIS进行三维地形建模分析。东月各流域长约14.0 km、平均宽度约3.4 km,在约47.3 km2的面积上具有2 849 m的高差。主沟下段沟长8.8km,高差1 084 m,平均比降101‰。B4支沟沟长2.6 km,平均坡降361‰。斜坡在40°~45°这一区间面积占比最高,为17.86%。结果表明,东月各流域属于中国泥石流小流域中面积最大的一类。泥石流形成区为B4支沟及邻近区域,以B4支沟为主。泥石流远程运移受到沟道纵剖面形态和平面形态共同影响。受地形条件影响,泥石流活动呈现单个大周期套叠多个小周期的模式。

In the early morning of August 18, 2010, a catastrophic debris flow occurred in the Dongyuege gully, a branch of the Nujiang river. It traveled a long distance of more than 8 km with a huge volume. In order to explore its occurrence mechanism, a quantitative study of the terrain condition is carried out. In addition to field investigation of the debris flow, the 1：1 000 scale longitudinal slope data is collected by field survey, and 1：10 000 scale digital line topographic data and ArcGIS software are used for the 3D terrain modeling and analysis. The Dongyuege basin has a length of 14. 0 km, an average width of 3.4 km, and a maximum elevation difference of 2 849 m in its basin area of 47.3 km^2. The lower segment of the main channel is about 8.8 km long and has a maximum height difference of 1 084 m and an average gradient of 101%o. The branch B4 is 2. 6 km long and its average gradient is 361‰. The slope range of 40° -45° has the highest area ratio of 17.86%. The results show that the Dongyuege basin is one of the largest debris flow basins of China. The formation zone is in branch B4 and its adjacent area. The remote migration of debris flow is closely related to profile morphology and plane morphology of the channel. Affected by the topography, the debris flow activities in the Dongyuege gully show a pattern in which several small cycles nested in a large period.