金沙江河谷——水系演化的崩滑外动力作用研究

在进一步研究金沙江河谷——水系发育的构造——气候机理基础上,认识到:山区深切河谷中普遍存在着大型堰塞现象:在青藏高原东南边缘地区,由于新构造运动强烈和地震频发及大暴雨等,在山高谷深的金沙江河谷中导致大型滑坡、崩塌或其他形式的外动力作用等,阻塞河谷水流,形成河谷堰塞湖,在堰塞体上游河谷形成静水沉积;在一定时间与条件下,堰塞坝溃决,在其下河谷中形成更大更急水流,加速河谷下切速率与深度,导致更大地形高差;新一轮新构造运动强烈和地震及大暴雨等,导致新一轮大型滑坡、崩塌等,形成新一轮河谷堰塞湖……如此多次重复,逐步加快与促进金沙江河谷——水系向现代形态演化,从而构成了金沙江河谷——水系演化的一种外力动力作用。这一认识对进一步研究山区深切河谷——水系形成与演化、工程建设选址评估和进行灾害防治等有普遍的参考价值与意义。

Study on the Collapsing and Landsliding External Dynamic Effect of the Valley and Drainage Evolution of Jinsha River

Based on the further analysis of the valley and drainage development structure of Jinsha River and the climatic mechanism,the results showed that there was the phenomenon of large-scale damming in the deeply incised valleys of mountain areas generally.And the valley of Jinsha River,with the high mountains,have formed the valley dammed lakes and deposition in standing water under the large-scale coast,landslip and other external dynamic process,which was caused by intense neotectonic movement,frequent earthquakes and heavy storm in the area of the southeastern margin of the Tibetan Plateau.Under given conditions and certain time,it formed the greater and more rapid flow and accelerated the valley incision rate and depth,and increased the terrain elevation continuously during the weir dam collapsed.A new round of landslide and collapsed occurred by the new neotectonic movement,earthquakes and heavy storm,and it formatted a serial valley dammed lakes.And repeated these several times,it will promote and accelerate the valley and drainage evolution of Jinsha River for the modern river morphology which formed an external dynamic process of the valley and drainage evolution.The results have an important reference value for the further study on the formation and evolution of the valley and drainage,the site assessment of engineering construction and disaster prevention.