植被对不同类型泥石流的抑制作用初探

通过对比四川省巴塘县的118处沟谷泥石流及33处坡面泥石流的植被覆盖率，发现植被对于坡面泥石流具有较好的抑制作用，但对沟谷泥石流作用则不明显。造成这种差别的原因在于坡面泥石流的物源主要是坡体表面侵蚀，植被根系组成的网状锚固层可以减缓乃至消除这种侵蚀效应；沟谷泥石流的物源主要来自沟岸崩塌，但植被对于中厚层的崩滑体锚固能力差，当降雨超过一定阈值后即可暴发泥石流。基于这种特点，建议将生物工程作为坡面泥石流的主要治理手段；对于沟谷泥石流而言，既不能将植被覆盖率作为易发程度的判别标准，也不宜作为综合治理中的主要环节。

Effect of Different Types of Vegetation on the Debris Flow Control

There are 118 valley debris flows and 33 slope debris flows in Batang County, Sichuan Province, China. All the vegetation coverage of these hazards has been verified through remote sensing and field investigation. It was found that the vegetation had an effect on the slope debris flow, while there was no correlation between the vegetation and valley debris flows. This difference exists because of the material source in different types of debris flows. The main material source of the slope debris flow results from surface erosion. Vegetation roots can restrain the erosion effect. But, the main sources of valley debris flow are collapses and landslides in the valley. In this case, vegetation does not work because of the deep slip surface in most collapses and landslides. So we suggest that bioengineering should be use for mitigating the slope debris flow. For valley debris flows, the vegetation is neither an active standard nor an approach to mitigation.