珠江河网分形机理研究

以不同时期珠江网河历史地图及遥感影像为基础,进行了河网分形计算,并从河道发育、人为活动等多个角度分析了珠江网河分形机理。在发育过程中,1883-2001年间河网分维值逐渐减小;在空间上,正干水道中潮道分维值大于分汊河道。分析认为,人为活动是导致珠江网河分形变化的主要因素:联围筑闸消灭横向支汊、口门整治及河道固化减小了河道冲决的几率、河道挖沙引起的水沙分流比变化改变了河道冲淤特性。

Fractal Mechanism of the Pearl River Network

The fractal dimensions of the river incarnate the river status,which has its inherent dynamical mechanism.The variation of fractal dimensions in different phases denotes the dynamic change in the same area.Based on the historic maps and remote sensing images in different periods,the fractal dimensions of the Pearl River network are calculated,and the fractal mechanism is analyzed from multiple perspectives,such as the hydrodynamics of network,the evolution of river channel,and man-induced impact on river network.The results show that: the fractal dimensions of the Pearl River network decreased gradually during the period of 1883~2001 as a whole;and the fractal dimensions of tidal channels in the artery were larger than those in the distributaries on space.As for the fractal mechanism,human activity has been increasingly an important factor leading to the change of fractal dimensions,e.g.the combination of dykes and construction of sluices diminish the amount of cross branches,estuarine renovation and solidification of river banks reduce the probability of bank breach,the rectification of division ratio of flow and suspended sand due to excavating sand from riverbed change the channel eroding or alluvial characteristics.