The Construction Identification Method Of Submarine Canyon And Characteristics Analysis Of Northern South China Sea

Submarine Canyon is one of the most common underwater geomorphic units in the continental margin,which is often developed in the middle and slope break zone of the continental shelf.The canyon's terrain is characterized by shallow deep strips or forked depression,its transverse sections are usually presented U form and V form.Submarine fan topography often occurs at the mouth of the canyon,which is the important channel to transport terrigenous clastic sediments and other granular sediments from terrene to abysmal sea.Because of its special geographical location and sedimentary environment,submarine canyon has been widely concerned by scholars at home and abroad.This text is based on the northern slope of the South China Sea area as the study area,which structured the recognition methods of submarine canyon,analyzed the distribution and morphological characteristics of submarine canyon,and established criteria for identification of submarine canyon in the northern slope of South China Sea.The results had strong guiding significance for recognizing and analyzing South China Sea submarine canyons.The study area was located in northern slope of South China Sea E114.5°-120.5°,N19°-22.7°,the depth of water was in the range of 20m-4000 m,which water depth and landform type changed greatly,what's more there are many geomorphic units of submarine canyons,ridges,seafloor depressions and faults.In this paper,a new method for automatic identification of submarine canyon based on manual supervision is studied.Based on the water depth data of northern slope of the South China Sea area of the study area construction of digital elevation model(DEM).On this basis,according to the geometric characteristics and physical characteristics of the submarine canyon,the identification is studied.Then the parameters of the identified submarine canyon are analyzed.The conclusions are as follows.(1)Based on the existing data and methods,a method based on digital elevation model(DEM)is proposed to automatically identify the submarine canyon in the study area.Recognize the submarine canyon step by step: it can automatically extract the feature line-valley axle wire of submarine canyon and the canyon valley wall.Validation results with existing canyons are shown,this method is effective and accurate.(2)Comparison of three different resolution DEM data for recognition of submarine canyon.DEM data with resolution of 1km had a better recognition effect for the grand canyon,which the length was more than 150 km,the average width was greater than 5km,and the maximum depth of cut is more than 300 m.DEM data with resolution of 500 m had a better recognition effect for the canyon,which the length was more than 50 km,the average width was greater than 3.5km,and the maximum depth of cut is more than 250 m.DEM data with resolution of 50 m had a better recognition effect for the canyon,which the length was more than 30 km,the average width was greater than 1km,and the maximum depth of cut is more than 200 m.(3)In this study,a total of 34 submarine canyons were identified,then the distribution and morphological characteristics were analyzed.They were divided into 31 slope canyons(which the canyon head check in continental slope)and 3 continental shelf slope canyons(which the canyon head cut to continental shelf)according to the study of the location of the submarine canyon.They were divided into 26 linear submarine canyons,1 serpentine submarine canyon and 7 dendritic submarine canyons according to the study of the submarine canyon.(4)Based on the morphological characteristics and distribution of the submarine canyon,summed up the standard of identification and determination of suitable for China's submarine canyon northern slope of the South China Sea Area...