基于可见光遥感测深技术的长江口南支河段河势演变规律研究

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

以长江口南支河段为研究区,利用Landsat ETM+遥感影像反演的1999年水下地形和该河段2002年实测水深数据,结合长江口来水来沙现状和河段特征,分析了河段的冲淤变化和沙体迁移规律,提出了需采取的治理措施。研究结果表明:(1)从1999到2002年南支河段总体发生冲刷,年平均冲刷量为0.192 6亿m3,河道内白茆沙、新浏河沙和新浏河沙包的沙头年平均后退467,374和421 m;(2)上、下扁担沙之间由于串沟发育,两者有分离的趋势,沙体5 m等深线的变动格局显示两沙体沙尾向下移动导致新桥水道上段水深加深、下段南侧水深变浅;(3)固定白茆沙和上、下扁担沙沙体,对维持南支河段航道的航运、稳定南北槽河势具有重要作用。

Taken the south branch of Changjiang Estuary as the study area, two bathymetric datasets,in which one is inversed by Landsat ETM＋ remote sensing image of 1999 and another 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 characteristics. 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. 192 6×10^8m^3 ; 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 five isobaths showed that the tail of the two shoals moved downward which led 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 maintenance of south branch as well as the river regime stabilization of south and north river courses.