西藏林芝扎木弄沟泥石流规模变化趋势研究

弄清扎木弄沟泥石流规模变化趋势,是进一步分析该沟潜在特大型泥石流发生频率的基础。基于钻孔资料和野外调查资料以及相关文献资料,采用光释光年代法和泥石流动力学参数计算法确定扎木弄沟在万年尺度下的泥石流规模变化过程。依据万年尺度下泥石流规模变化过程和现今区域内外动力条件,分析了扎木弄沟今后泥石流发展变化趋势。研究结果表明:扎木弄沟万年尺度下泥石流规模呈波动减小过程,特大型泥石流规模随时间逐渐减小,且在特大规模泥石流发生后的数十年间,汇流型泥石流规模也逐渐减小;扎木弄沟内还具备外动力条件,经历一定时间的累积(有可能是千年尺度或者百年尺度),今后扎木弄沟泥石流灾害仍易于发生,并且再次发生的特大型泥石流规模会小于2000年泥石流规模。特大型泥石流灾害发生后,灾害还将延续一段时间,汇流型泥石流规模呈逐年减小趋势。

Variation trend analysis on debris flow scale in Zhamunong Gully

The variation trend analysis on debris flow scale of Zhamunong Gully is the basis for further analysis on the frequency of potential giant debris flow. Based on borehole data, field survey data and relevant literature, we determine the variation process of the debris flow scale under ten thousand years scale by using Optically Stimulated Luminescence method and debris flow parameter calculation method. According to the variation process and the condition of endogenic and exogenic geological processes at present, we research the future development trend of the debris flow in Zhamunong Gully. The results show that: (1) the debris flow scale decreases under ten thousand years scale in fluctuation, the giant debris flow scale also decreases, and the confluence-type debris flow scale also gradually reduce during the decades after the occurrence of giant debris flow. (2) There still has endogenic and exogenic geological processes conditions in Zhamunong Gully and the giant debris flow is prone to occur after a period of time(maybe thousand years scale or century scale), but the scale would be less than the giant debris flow in 2000. After the giant debris flow, many other disasters would continue for a while.