珠江河口水下三角洲冲淤演变分析

Analysis on morphological evolution of underwater delta in the Pearl River Estuary

基于历史地形数据,建立珠江河口水下三角洲数字高程模型分析近期的水下地形变化。并分析上游径流来沙和人类工程活动对河口区水下地形冲淤演变的影响。结果显示在20世纪60年代到2000年左右期间,水下三角洲地形基本处于淤积状态,只有深槽等局部区域发生冲刷。20世纪90年代期间,黄茅海水域和伶仃洋水域的淤积强度有减弱的趋势,而鸡啼门水域淤积强度增强,磨刀门水域表现为滩淤槽冲的状态。上游径流来沙除伶仃洋水域外都表现出减少的趋势,一定程度上减弱了这些区域的淤积强度。而人类活动如土地围垦,航道整治对河口区水下地形的变化有十分重要的影响。

Underwater Digital Elevation Models （DEM） of the Pearl River Estuary were built based on the historical bathymetric charts to analyze quantitatively morphological changes of underwater delta. The impacts of sediment supply and human activities on morphological evolution of underwater delta were analyzed. During the period between 1960s and 2000s, the results suggest that the PRD experienced a major stage of accretion, with net erosion only in some local zones such as deep channels. During the 1990s, sedimentation in Huangmao Bay water area and Lingding Bay water area showed a decreasing trend, but increased in Jitimen water area. And Modaomen water area was in a state that shoals silted and deep troughs scoured during the 1990s. Sediment supply from upstream decreased except Lingding Bay water area, which led to a weakening trend of sediment deposition in these regions. Human activities such as land reclamation and waterway regulation have significant impacts on morphological evolution of underwater delta.