近60年来珠江三角洲河床演变分析

Fluvial processes in the Pearl River Delta in recent decades

20世纪50年代至21世纪初的实测河床地形资料分析表明,珠江三角洲网河区干支流河道及主要入海水道在人类活动及来水来沙变化的共同影响下,出现了不同程度的下切演变。西江干流河道在1999年前以淤积为主,1999年后,随着人类活动强度的增大,河道严重冲蚀。北江干流河道在1960年前呈自然淤积的状态,1960年后,河道河床严重下切。20世纪60年代至90年代末珠江三角洲支流河道普遍下切,且程度不均。20世纪90年代初至21世纪初,珠江入海口门水道中,洪奇沥和磨刀门水道下切较为明显,蕉门及崖门水道受采砂影响,出现异常深坑。初步分析表明来沙减少对西江河床下切的最大贡献率约为26%,采砂活动和航道整治是珠江三角洲快速下切的主要原因。

The observed geomorphology and cross section data of the pearl river delta channel from 1950s to the early 21st century are analyzed. The study found that the main channel,branch river and the estuary in the pearl river delta have incised inordinately in recent decades under the influence of the human activities and the changes of income water and sediment. The main river of Xi Jiang was priority to siltation before 1999,after 1999,with the increase of the intensity of human activities and serious erosion of the channel,riverbed incised significantly. The main river of Bei Jiang in the state of natural sedimentation before 1960,after 1960,the river bed incised seriously. The branch river of the pearl river delta incised unevenly in the 1960s to 90s. Between the sea-entering channel in the pearl river estuary,Hongqili and Modaomen channel incised evidently,Jiaomen and Yamen channel influenced by sand-excavating,there appeared abnormal deep pit in the early 1990 s to the early 21st century. The result showed that the largest contribution rate of income water and sediment changes to river sedimentation in Xi Jiang and Bei Jiang is about 26% and 33%,sand mining and waterway regulation is the main reason for the rapid incised of pearl river delta.