Yangyun town is a place where debris flow frequently happens in Gaizhou city and suffers from economic loss. This paper, based on the debris flow happened in July, 1981, studies the debris flow accumulation, terrain and vegetation, analyzes the features and conditions of debris flow. This study indicates that this debris flow is derived from flooding, large, accumulating coarse gravels, poor sorting and roundness. Materials are from the nearby mountain, weathered granite. Debris flow most occurs in the rainstorm seasons in July to August, follows along steep and deep valleys and accumulates in the valley mouth. The rainstorm is an evocator for this debris flow.

The southeast Tibet terrain with deep valleys and steep mountains is abundant in geological disasters such as landslides. This paper analyzes the landslide development regularity, discusses the relation between landslides and terrain, lithologies, structures, and rainfalls. The landslides occur during the rainy seasons May to September, most in June. The landslides trend to occur in sandstone, shale, mudstone, and active faults areas, but not in the granite and gneiss areas. Slope with over 30 degrees is also favorable for landslides.