八角楼乡火后泥石流空间发育特征

作为一种与林火密切相关的特殊泥石流，火后泥石流的形成具有明显的空间差异性，对其空间发育特征及影响因素的分析有利于此类泥石流的防灾减灾. 运用现场调查、室内外试验和遥感解译等手段，对雅江县八角楼乡火烧迹地15条沟道的火后泥石流发育特征及地形、林火、植被特征、降雨条件进行了多元分析. 结果表明:火烈度越强，土壤的物理力学性质劣化越严重，斥水性越强，渗透性越低，泥石流越易形成；流域过火面积越大，植被覆盖率越低，泥石流暴发频率越高；相对于大流域，小而陡的流域反而更易暴发火后泥石流. 此外，研究区内暴发的5次火后泥石流中有4次泥石流其激发雨强重复周期均小于5 a，且随着时间的增长激发雨强也逐渐升高. 

Spatial Development Characteristics of Post-Fire Debris Flow in Bajiaolou Town

As a special type of debris flows closely relevant to forest fire, the generation of post-fire debris flow often shows a spatial variation. It is of great significance to analyze the spatial development characteristics and its influencing factors for hazard mitigation and reduction. By means of field investigation, in-situ and laboratory tests, and remote sensing interpretation, multi-factor analysis was conducted on the 15 channels in the burned area in Bajiaolou town of Yajiang county in terms of their spatial development characteristics, topography, forest fire, vegetation and rainfall conditions. The results show that the higher the fire intensity, the stronger the soil water repellency and the lower the permeability; moreover, the physical and mechanical properties of soil deteriorate more seriously, which contribute to the generation of post-fire debris flow. The occurrence frequency of post-fire debris flow rises when the burned area become larger and the vegetation cover coefficient lower. In contrast to the large basins, the smaller basins show more vulnerability to post-fire debris flow for their short channel lengths and high longitudinal slopes. Besides, the recurrence time of the triggering rainfall intensity that corresponds to four of five debris-flow events in the study areas is less than 5 years, and the triggering rainfall intensity also increases with time.