Impact of anthropogenic drivers on subaqueous topographical change in the Datong to Xuliujing reach of the Yangtze River  

作　　者：Shuwei ZHENG Heqin CHENG Shengyu SHI Wei XU Quanping ZHOU Yuehua JIANG Fengnian ZHOU Minxiong CAO 

机构地区：[1]State Key Laboratory of Estuarine and Coastal Research, East China Normal University [2]Nanjing Geological Survey Center,China Geological Survey [3]Yangtze River Water Resources Commission, Yangtze River Hydrology and Water Resources Survey Bureau [4]Nanjing Hydraulic Research Institute, State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering

出　　处：《Science China Earth Sciences》2018年第7期940-950,共11页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 51761135023 & 41476075);the China Geological Survey (Grant No. DD20160246)

摘　　要：Changes of subaqueous topography in shallow offshore water pose safety risks for embankments,navigation,and ports.This study conducted measurements of subaqueous topography between Datong and Xuliujing in the Yangtze River using a Sea Bat 7125 multi-beam echo sounder,and the channel change from 1998 to 2013 was calculated using historical bathymetry data.The study revealed several important results:(1)the overall pattern of changes through the studied stretch of the river was erosion–deposition–erosion.Erosion with a volume 700×10~6m^3occurred in the upper reach,deposition of about 204×10~6m^3occurred in the middle reach,and erosion of about 602×10~6m^3occurred in the lower reach.(2)Dunes are the most common microtopographic feature,accounting for 64.3%of the Datong to Xuliujing reach,followed by erosional topography and flat river topography,accounting for 27.6%and 6.6%,respectively.(3)Human activities have a direct impact on the development of the microtopography.For instance,the mining of sand formed holes on the surface of dunes with lengths of 20–35 m and depths of 3–5 m.We concluded that the overall trend of erosion(net erosion volume of 468×10~6m^3)occurred in the study area mainly because of the decreased sediment discharge following the closure of the Three Gorges Dam.However,other human activities were also impact factors of topographic change.Use of embankments and channel management reduced channel width,restricted river meandering,and exacerbated the erosion phenomenon.Changes of subaqueous topography in shallow offshore water pose safety risks for embankments,navigation,and ports.This study conducted measurements of subaqueous topography between Datong and Xuliujing in the Yangtze River using a Sea Bat 7125 multi-beam echo sounder,and the channel change from 1998 to 2013 was calculated using historical bathymetry data.The study revealed several important results：（1）the overall pattern of changes through the studied stretch of the river was erosion–deposition–erosion.Erosion with a volume 700×10^6m^3occurred in the upper reach,deposition of about 204×10^6m^3occurred in the middle reach,and erosion of about 602×10^6m^3occurred in the lower reach.（2）Dunes are the most common microtopographic feature,accounting for 64.3%of the Datong to Xuliujing reach,followed by erosional topography and flat river topography,accounting for 27.6%and 6.6%,respectively.（3）Human activities have a direct impact on the development of the microtopography.For instance,the mining of sand formed holes on the surface of dunes with lengths of 20–35 m and depths of 3–5 m.We concluded that the overall trend of erosion（net erosion volume of 468×10^6m^3）occurred in the study area mainly because of the decreased sediment discharge following the closure of the Three Gorges Dam.However,other human activities were also impact factors of topographic change.Use of embankments and channel management reduced channel width,restricted river meandering,and exacerbated the erosion phenomenon.

关 键 词：Subaqueous topographical Human activities Multi-beam echo sounder High resolution Yangtze River 

分 类 号：P332[天文地球—水文科学]