基于GIS的长江梅子洲头护岸工程对河势演变的影响分析

以长江下游南京梅子洲河段1959、1970、1983、1992和2003年水下地形图为基础资料，以此建立相应年份的数字高程模型（DEM）并进行了分析，探讨护岸工程修筑前后该河段的时空演变规律，进而分析其在河势控制中的作用，为河道整治和保持优良河势提供依据。护岸工程修筑前后，1#、2#、3#三个断面的岸线摆动速率分别由500、1880和4364 m/a减小为115、600和915 m/a，主泓线摆动速率分别由845、3118和5000 m/a降至550、535和475 m/a，宽深比分别由424、320、257减小为393、278和225。结果表明，实施护岸工程后，该河段左侧岸线及主泓线的摆动幅度明显变小，河道的平面变形得到有效控制。梅子洲头滩遵循一般边滩演变规律，由护岸前的宽浅逐渐变为窄深，河道趋于稳定。长江三桥对梅子洲头上游河段的河势将进一步起到控制作用。

EFFECT OF SHOAL HEAD REVETMENT ON FLUVIAL PROCESS OF THE MEIZIZHOU REACH OF THE YANGTZE RIVER BASED ON GIS

The evolution processes for Meiizhou reach in the Yangtze River were studied based on the digital elevation models(DEM) of the lower reach of the Yangtze River for the years of 1959,1970,1983,1992 and 2003.Three profiles were investigated.The shift velocities of the water-front of the profiles,1#,2# and 3#,were respectively 5.00,18.80 and 43.64 m/a,in the stage before the construction of the revetment.But these decreased to 1.15,6.00 and 9.15 m/a thereafter.The shift velocities of the thalweg changed from 8.45,31.18 and 50.00 m/a to 5.50,5.35 and 4.75 m/a,the proportion of the width and depth,changed from 4.24,3.20 and 2.57 to 3.93,2.78 and 2.25.These results indicate that since the revetment has been finished,the shift range of left bank and thalweg has decreased distinctly and the channel planar distortion is controlled effectively.The shoal head of Meizizhou has become deeper and narrower.The river channel shows the tendency of stability.The Third Nanjing Yangtze River Bridge has good effect on controlling the evolution process of the Meizizhou reach in the Yangtze River.