2013年洪季长江口南港沙波运动观测与分析

Field study on sand wave movement in the Changjiang( Yangtze) Estuary

基于2013年6-7月最新的沙波观测资料和近年来多次野外洪枯季沙波、底质观测资料,探讨了长江河口南港-圆圆沙河段沙波分布特征及变化趋势。结果表明:南港-圆圆沙河段区域河床沉积物颗粒较粗,中值粒径均在0.1mm左右,属于细砂类,分选系数较好,为沙波的形成和发育提供了良好条件。南港河段沙波普遍存在,以平直二维沙波为主,沙波对称性良好,以陡坡向海为主。横沙通道口外附近以及圆圆沙航道沙波对称性指标部分大于1,呈陡坡向陆趋势。长江口沙波发育尺度呈自西向东逐渐减弱态势,自1997年以来南港沙波范围逐渐增大,尤其逐渐向下游推展,直至圆圆沙航道,2006-2013年再次下移17km,洪、枯季沙波发育尺度差别较大。

Based on data of bed sediments and sand waves during June 29 to July 2, 2013 and July 6 -12, 2013 in the Changjiang estuary, China, and other bed sediments and sand wave data in recent years, sand wave distribution characteristics and change tendency were discussed. Results show that in the Nangang- yuanyuansha region, bed sediment particles median diameter was around 0. 1 mm, as part of the fine sand with sorting coefficient, the surroundings provides a good condition for the formation and development of sand waves. Sand waves were widespread in the Nangang-yuanyuansha region, the main feature of dunes is consist of 2D dunes with good symmetry, abrupt slope of dunes to downstream. Sand wave scale was gradually weak- ened from the west to the east. From 1997 the regime termination of sand waves in the Changjiang estuary has put up a expanding trend toward downstream direction in the South Channel, with a migration of 17km from 2006 to 2013. Sand wave development dimension was different during flood season and dry season, the scale of dunes in dry season is extremely smaller than that in flood season.