Study on the evolution trend of the south branch of Changjiang Estuary in China based on bathymetry reversion method of visible remote sensing

Taken the south branch of Changjiang Estuary as the study area,two bathymetric datasets,in which one is inversed by Landsat ETM+ remo tesensing image of 1999 and anot her is surveyed in 2002, were used to analyze the erosion and deposition rule of the reach and sand body movement pattern which was combined with the Changjiang River runoff discharge and sediment movement charact eristics.Results indicated that(1)from 1999 to 2002 the general variation trend of the south branch was erosion and the annual erosion amount was about 0.1926×10⁸ m³;three sand shoal bundles,namely,Baimao sand shoal, New Liuhe sand shoal and New Liuhe sand shoal bundle were all eroded with the backing distances about 467,374 and 421 m/a respectively;(2)upper and lower Biandan sand shoals had the trend of separation because of the development of the erosion ditch between them.The changing patterns of the fiveiso baths showed that the tail of the two shoals moved downward whichled to the deeper water depth of Xinqiao Channel and lower one of its south side;(3)fixing Baimao sand shoals,and upper and lower Biandan sand shoals were very important for the channel navigation maint enance of south branch as well as the river regime stabilization of south and north river courses.