邛海山洪泥石流淤积特征与趋势分析

通过流域最典型支流官坝河山洪泥石流堆积特征调查,分析邛海泥沙淤积变化状况,探讨邛海山洪泥石流淤积特征以及发展趋势。结果表明,1950年以来,邛海泥沙淤积达到0.52×106 m3;山洪泥石流携带的泥沙堆积特征为粗颗粒(粒径2mm)沿沟床堆积,细颗粒大多被输移到邛海;山洪泥石流形成的堆积扇促使邛海湖岸线向湖心不断推进;邛海流域山洪泥石流潜入邛海湖底,形成浊流在湖底继续运动,形成湖底水下堤及冲沟,改变邛海湖底地形。在强地震和强降雨等多因素的偶然联合作用下,邛海流域可能会发生大规模的山洪泥石流。

Silt deposit characteristics and trend analysis of torrential flood debris flows in Qionghai Lake, Xichang, China

This paper investigates the accumulation characters of the debris flows of the flash floods in the most typical tributaries in the Qionghai basin of Guanba river,Sichuan,China,analyses the changes of silt deposit in Qionghai,and explores the deposit characters and development trend.Based on this,the authors draw the following conclusions.Firstly,since 1950,520 thousand cubic silt have deposited in Qionghai.Secondly,the deposit character of silt carried by debris flows of flash flood is that coarse particles(diameter >2 mm) accumulate along the ditch bed,while the fine particles are transported to Qionghai.Thirdly,the depositional fan formed by debris flows of flash flood impels the Qionghai lake shoreline to push on to the lake core constantly.Fourthly,the debris flows of flash flood sneak into the sublacustrine,forming the turbidity current in the lake and continuing to move,as well as forming sublacustrine underwater embankments to change the sublacustrine topography.Finally,with the combining effects of strong earthquakes,rainfalls and other causal factors,large-scale debris flows of flash flood may take place in Qionghai.