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李子凹沟和滑脚坡沟是著名高频泥石流沟蒋家沟中游流通段的两条支沟,流域条件极为相似,泥石流暴发频率高,堆积扇发育快。以这两条沟为对象,观察泥石流在堆积扇上的运动和停积过程,对不同特征的泥石流堆积体进行采样分析,并在每年雨季前后测量堆积扇地形及其纵横断面。对这两条支沟泥石流堆积扇2006～2008年的发育过程、平面形态、纵横剖面、堆积速度等进行分析,得出如下结论:(1)滑脚坡沟泥石流体颗粒较粗,容重大,泥石流整体堆积,呈垄岗状。李子凹沟泥石流粗大颗粒少,容重小,在扇体上漫流,堆积呈舌状。堆积扇的进一步发育主要靠垄岗状堆积-改道完成。(2)主沟堆积条件下,支沟泥石流堆积扇以淤高为主,且淤高幅度在扇体上下部分布均匀。(3)泥石流堆积扇发展到一定程度后,纵比降基本稳定,表现为剖面上发生持续且较为均衡的堆积。横剖面在主沟上游方向的坡度较小。
Pitch ditch and slippery slope ditch is a well-known high-frequency debris flow ditch Jiangjiagou middle part of the two branch ditch, watershed conditions are very similar, debris flow outbreak frequency, rapid development of accumulation fan. Taking these two ditches as object, we observed the movement and de-deposition process of the debris flow on the stacking fan, sampled and analyzed the debris flow debris of different characteristics and measured the topography and aspect of the stacking fan before and after the rainy season. The development process, plane morphology, vertical and horizontal cross-section, accumulation velocity and so on of the debris flow debris accumulating fan in the two branch valleys from 2006 to 2008 are analyzed. The conclusions are as follows: (1) The debris flow in the slump slope ditch is coarse, Debris flow as a whole pile up, ridge-shaped. Plum Gully Debris flow coarse particles less weight, small, diffuse in the fan body, the accumulation of tongue-like. The further development of the accumulation fan mainly depends on the ridge-shaped accumulation - diversion completed. (2) Under the condition of main channel accumulation, the silt accumulation in the branch gully is dominated by siltation, and the silt height is evenly distributed on the upper and lower sectors of the fan. (3) After the debris flow fan has developed to a certain extent, the vertical and horizontal drop are basically stable, showing a continuous and balanced accumulation in the profile. The slope of the cross section in the upstream direction of the main channel is smaller.