1999年6月16日大咕噜沟泥石流

通过对岷江大咕噜沟 1999 0 6 16泥石流的数次现场考察与观测 ,首先叙述了本次泥石流的活动及其危害情况 ,描述了泥石流的形成条件 ,指出了泥石流发生的原因 ,认为本次泥石流是由于大咕噜沟流域内物质的含水量较高 ,在连续暴雨的条件下其含水量将会超饱和 ,引起二岔沟以上南支右岸海拔 3750m处的沟岸滑 ,进而产生泥石流的。然后对流沟沟床演变以及单侧支流入汇的影响进行了分析 ,认为大咕噜沟主沟呈串珠状沟道 ,平面上宽窄相间 ,纵剖面为深潭—跌水形式 ,跌坎的形成通常有以下三种情况 :一种是沟床本身为岩石或含有岩石 ,一种是两岸崩塌或滑坡而残留的粗大堆积物形成 ,一种是支流的冲出物或堆积扇形成。另外 ,同岸支沟的存在使主河逼近对岸 ,在岩坡稳定性较差的条件下 ,使对岸产生相当规模的崩塌或滑坡。最后 ,提出防治泥石流灾害的建议。

FIELD INVESTIGATION OF DAGULUGOU DEBRIS FLOW ON THE MINJIANG RIVER

Field investigations were carried out to examine the cause and process of a debris flow,which occurred in the Dagulugou gully on 14+{th} June 1999.The gully is located in Songpan county,the northwest of Sichuan province,and is a small tributary of the Mijjiang River.The process and the cause of the debris flow were described in detail in this paper.It is indicated that the debris flow is mainly caused by the continuous heavy rainfall in the area and then the landslide of the right bank at an attitude of 3 750 m above sea level on the south tributary.The fluvial process of the main stream and the impact of the one side tributaries on the main gully were analysed.Three types of bed descents could be divided for the pool riffle system according to the formation process.One of bed descents of of rocky gully that is difficult to degrade by flow,one is of bulky deposit collapsed from the gully banks,and the another is alluvial fan of tributaries.