Hydrogeomorphic processes in a steep debris flow initiation zone
Hydrogeomorphic processes in a steep debris flow initiation zone
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DOI：
10.1029/2006gl026250
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发表时间：
2006-05
影响因子：
5.2
通讯作者：
F. Imaizumi;R. Sidle;S. Tsuchiya;O. Ohsaka
中科院分区：
文献类型：
--
作者：
F. Imaizumi;R. Sidle;S. Tsuchiya;O. Ohsaka
许多泥石流始于陡峭的河道（>20 度），但研究主要集中在坡度较低的溪流上，其中破坏由河道沉积物上方的水高度控制。日本中部 Ohya 滑坡陡峭通道中的多次泥石流与填充过程（即冻融和干散）和累积沉积物的部分饱和有关。由于该流域地貌过程非常活跃，过去6年共观测到39次泥石流。事件前后的图像表明，在大多数泥石流（包括饱和流和非饱和流）期间，较细的物质会选择性迁移；然而，对于在较平缓的河道中引发泥石流很重要的河流沉积过程却很少。这种不饱和材料运动的临界条件是通过将剪切应力与通道床的固体摩擦力等同而得出的。
Many debris flows initiate in steep channels (>20 degrees), yet studies have focused on lower‐gradient streams where failure is controlled by water height above channel deposits. Multiple debris flows in a steep channel in Ohya landslide, central Japan, were linked to infilling processes (i.e., freeze‐thaw and dry ravel) and partial saturation of accumulated sediment. Because of very active geomorphic processes in this catchment, 39 debris flows were observed in the past 6 yr. Pre‐ and post event imagery indicates selective transport of finer materials during most debris flows that comprise saturated and unsaturated flows; however, fluvial sediment processes, important in relation to debris flow initiation in gentler channels, were minimal. Critical conditions for the movement of such unsaturated materials are derived by equating shear stress with solid friction of the channel bed.