Tributaries of the upper course converge by the middle course. Water flow increases, as do the river's erosive and carrying capacity, resulting in geomorphology unique to the middle course, with features such as meanders and bluffs. A meander is a deep curve in the channel created by the erosion being strong along the inner margin of the curve, while deposition dominates along the outer margin. A bluff is a steep slope along the riverside, formed by lateral erosion of interlocking spurs along the stream.

In addition, lateral erosion becomes severe because of the increased water flow. The valleys are V-shaped - albeit the "Vs" are mostly irregular, and broader than along the upper course. In Hong Kong, there is often no obvious middle course between the steep upstream and gentle downstream sections.

Meander (Lam Tsuen River)

Bluff (Lam Tsuen River)

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