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.