Based on the distribution of tributaries, local rivers can be mostly classified into three drainage patterns: dendritic, rectangular and radial.

Dendritic Drainage Pattern
Dendritic drainage is the most common drainage pattern in Hong Kong. Tributaries from the upper course merge with the main stream at fairly regular intervals. The angle between the major channel and its tributaries is less than 90 degrees, similar to that between a tree trunk and its branches. Shan Pui River, Kam Tin River and the upper to middle Lam Tsuen River exhibit typical dendritic drainage patterns, reflecting relatively simple geology in their basins.

Rectangular Drainage Pattern
In rectangular drainage patterns, the major channel and its tributaries are connected at angles close to 90 degree. This can occur if faults and joints in the bedrock are arranged at right angles, so rivers and streams flow and erode along these lines of weakness. Granite regions of the western New Territories have such jointing, resulting in obvious rectangular drainage patterns along streams such as Sham Tseng Stream and the upper course of Tuen Mun River (above Tai Lam Reservoir).

Radial Drainage Pattern
Radial drainage patterns comprise several streams that diverge from the same point. Streams and rivers often radiate in all directions from the peaks of mountains. This pattern is generally found on roughly conical mountains such as Tai Mo Shan and Sunset Peak.

 




Dendritic Drainage Pattern


Rectangular Drainage Pattern


Radial Drainage Pattern

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