珠江河口近期岸线演变及其原因

Coastline evolution and its cause of the Pearl River Estuary in recent years

基于不同时段的珠江河口卫星遥感图像,结合遥感-地理信息系统(RS-GIS)集成技术定量计算分析岸线近期的冲淤变化。从海平面上升和上游来沙等自然演变条件及人类工程活动两大方面分析珠江河口岸线冲淤演变的原因。结果显示:在1976—2006年,珠江河口近岸岸线整体向海淤涨579.2 m,年均淤涨19.3 m,而外海岛屿岸线总共淤涨21.6 m,年均淤涨0.7 m,近岸岸线的淤涨速率远快于自然演变过程。自然条件变化如海平面上升,在河口岸线剧烈的变化中影响较小。20世纪90年代期间上游来沙的减少与岸线淤涨速率变快的结果并不一致。详细的对比分析说明珠江河口地区的土地围垦是其岸线剧烈变化的主要因素。

Multi-temporal satellite remote sensing images were used,in combination with RS-GIS integration technology,to calculate and analyze coastline changes of the Pear River Estuary（PRE）.The coastline＇ s responses to natural factors such as sea-level rise and sediment supply and human actives are analyzed.The results show that offshore coastline extends seaward by 579.2 m,with an extension rate of 19.3 m/a from 1976 to 2006.Moreover,during the same period,open-sea island coastline only extends seaward 21.6 m with an extension rate of 0.7 m/a,which suggest that extension rate of offshore coastline is much faster than by natural aggradation process.Sea-level rise,seem to have minor impacts on the dramatic changes of coastlines of the PRE.The increasing trend of coastline extension rate does not agree with the decreasing trend of the sediment supply from upstream in the 1990 s.A detailed comparative analysis indicates that land reclamation is the most dominant factor that controls the observed coastline changes.