Based On DEM, The Study Of Tectonic Geomorphology And Water System Evolution In The Upper Reaches Of The Minjiang River In The Longmenshan Area

The Tibetan plateau is formed by the collision of the Eurasian plate and the Indian plate to form the highest plateau in the world since Cenozoic era.It is known as the "roof of the world" and "third pole".The eastern margin of Tibetan plateau is also known as the Longmen mountain area.The Cenozoic tectonics and surface processes are of great significance to the study of the formation and evolution of Tibetan plateau.Longmen mountain tectonic belt is becoming the focus of international geology because of its variety of tectonic style and special tectonic position,strong complexity and the historical evolution,especially since the 2008 Wenchuan Ms8.0 earthquake.Tectonic geomorphology and the water system is extremely sensitive to tectonic activity,the author aims to explore the tectonic activity in Fujiang river upstream,Longmen mountain area,by studying the relationship between drainage characteristics and tectonic activities.Based on geographic information system(GIS)technology,remote sensing(RS)technology,Landsat8 satellite remote sensing image and DEM data,Fujiang river upstream,Longmen mountain area extract water system and interpret fault zone.On the basis of analyzing and predicting the predecessors' data,the relationship between the extracted water system and the untied fault zone is studied.The research results can provide reference for the study of the active structure of Fujiang river upstream,Longmen mountain area.Based on the DEM data,the spatial analysis of the basic tectonic geomorphology of the study area was carried out with the help of ArcGIS10.1 software.The results indicated that Fujiang river upstream and Longmen mountain area have obvious terraces and the elevation decreases from southeast to northwest.The elevation of fujiang River pass Longmen mountain and fujiang river in the middle of the study area and its tributaries around are low.The distribution of high elevation areas is the least.High altitude areas are mainly located in the northwest area and influenced by the erosion of Fujiang River,indicating jagged shape.The fluctuation in the middle area surrounding River is in range of 200-400 m with the largest proportion.Water system and DEM data were processed by the remote sensing images,and the the DEM data were corrected.The corrected DEM data were extracted and classified by the hydrological model in ArcGIS10.1,showing that the total river length in study area is 2430.93 km.The first degree river has the longest length of 1154.26 km,with a percentage of 47.48%.The distribution of water density in the study area are within the range of 6-1000.The high value area with water density greater than 570 are striped.The density of the water system in thesoutheastern part of the study area is the largest.The information of fracture zone was extracted by the SRTM-DEM data,Landsat 8 remote sensing images and the geological map of the study area.The information of fracture zone was extracted and interpreted with 3D simulation technology and ArcGIS spatial analysis technology.One of the fractures in northwest-southeast direction and 18 fractures in northeast-southwest direction was extracted with the filed research and the existing data.The extraction of fault zone and drainage stack indicated that there is a close relationship between morphological characteristics and tectonic activity in water.The water flows through the fault often occurs when the change of direction,under the influence of fractured zone makes water river merging in active fault zone along the fracture zone formed near the fracture zone and roughly linear drainage in parallel,tectonic fault zone often the catchment formed obvious water density,high value area is mostly located in tectonic fault zone.