南海岛礁附近悬浮泥沙时空分布的遥感研究

RemoteSensing of Spatial-temporal Distribution of Suspended Sediment Surrounding Islands and Reefs in the South China Sea

岛礁附近海域的悬浮泥沙分布时空变化对研究岛礁生态环境有重要影响。基于30 m高分辨率的Landsat 8陆地成像仪影像,利用经验算法反演南海岛礁附近水体悬浮泥沙浓度。研究结果显示,南海永暑礁有3个明显的高悬浮泥沙区,位于西南部、东北部和潟湖,环礁美济礁和渚碧礁的高悬浮泥沙区主要位于潟湖内。在时间序列上,悬浮泥沙增加主要出现在岛礁填岛阶段。在空间上,悬浮泥沙较高值分布最远约离岛10 km,基本分布面积在25 km^2以内。高悬浮泥沙分布区的方位也与同期海域的物理环境,特别是风场和流场的方位相关。岛礁建设活动与海域物理条件在短期内对附近海域悬浮泥沙分布造成明显影响,填岛工程完成约14 d后,悬浮泥沙基本恢复至原有水平。

Spatial-temporal distribution of Suspended Sediment(SS)in the waters near the islands and reefs have important effect on the ecological environment of reefs.Landsat-8 Operational Land Imager(OLI)data,with a resolution of 30 m,were applied to retrieve SS concentration using empirical algorithm.Results showed three obvious high SS areas,the southwest part,the northeast part and its lagoon surrounded Yongshu Island;While,in the Meiji and Zhubi Island,high SS areas appeared mostly in the lagoon.Time series data indicated that the SS increased mainly during islands and reefs building period.The farthest range of SS distribution is about 10 km away from the island,and the maximum influenced area is about 25 km^2.At the same time,the directions of SS distribution well matched with directions of wind and current.These islands and reefs building activities and physical situations significantly affected SS distribution in the island environments during a certain period of time,and the SS concentration restored to normal levels after islands and reef buildings finished.