Study On The Relationship Between Dam And River Geomorphologic Evolution In The Upper Indus River

The upper Indus river is located at the junction of the Eurasian plate and the Indian plate,which belongs to the western Himalayan syntaxes.The strong uplift of the terrain caused by the squeeze between the plates,which has led to frequent geologic hazards such as large-scale collapses,landslides and debris flows,and a large-scale blocking river dam has seriously affected the safety of local people's lives and property as well as the prosperity and stability of the China-Pakistan Economic Corridor.The digital topographic analysis of the river can not only understand the characteristics of the river geomorphologic evolution in the region,but also further understand the evolution mechanism of the regional geomorphologic evolution by analyzing the relationship between the dam and the river geomorphologic evolution.The paper based on remote sensing and digital terrain analysis combining the two methods to study the evolution of the Indus river upstream dams and rivers landscape.Through the human-computer interaction remote sensing and field survey,the distribution of the Indus river upstream dams can be obtained,based on the 30 m SRTM DEM of river digital terrain analysis,get the Indus river profile,Chi-plot,the slope area of logarithm,steep and steep index distribution,such as figure,river knickpoint comprehensive recognition,and preliminary judge river knickpoint type.At the same time,the spatial superposition of the location,fault,lithology distribution of the river fracture point and the dam can obtain the main controlling factors of the river knickpoints.The research results are as follows:(1)Through remote sensing interpretation and local field investigation,121 dams(with a volume greater than 0.001km~3)were found in the upper Indus river region,which are mainly landslide dams.The dam body is relatively large in scale,which are mainly between 0.01 and 0.1km~3;The dam height is mainly between 100 and 200meters,which is relatively high.It is mainly located in middle and high altitude areas of2000-5000m.In the Hunza river valley,the dams are the most densely distributed,which most of them are glacier or moraine dams.The dams on the trunk river of the Indus river are mainly distributed in the middle and lower reaches of the river,which are mainly landslide and debris flow dams.(2)The longitudinal profile of the trunk rivers of six major rivers in the upper Indus region was analyzed,and it was found that the longitudinal profile of all the major rivers had obvious convex region,especially that the Indus and Shyok rivers developed significant knickpoint.The high values of the steep index of the Indus,Shyok and Astor rivers are mainly concentrated in the middle and lower reaches,indicating that the erosion rate of the middle and lower reaches is fast and mainly dominated by erosion landform.However,the steep index of the Hunza river and Gilgit rivers are mainly concentrated in the middle and upper reaches,which indicate that the middle and upper reaches of the river have a fast erosion rate and are mainly based on erosion topography.(3)Through the river profile,Chi-plot,such as slope area of feature extraction and discriminant river knickpoint types,which damming knickpoint is in the majority in the upper Indus river region.In addition,we make the spatial superposition comparison of the dam of some rivers with river kinckpoint and fault lithology.It is found that the dam and the river knickpoint have a good fit,indicating that the dam affects the formation and migration of river knickpoint in this area to some extent.(4)Dams and rivers profile,steep index space comparison found that that the high value of steep index has a good correlation with the dam.The variability of river profile of most rivers are related to the dam in this area,which elevates the local erosion base level in the upstream of the dam body.It indicates that the dam affects the geomorphologic evolution of the river in this region,which form the knickpoint in river channel,and delay the river headward erosion,protected the integrity of the the Tibetan Plateau.