HKDSE Geography/M2a/Drainage Basins

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There are many definitions in the following chapters. You need not recite them! Simply learn what they mean, as well as the associated keywords. There are a few definitions that you should recite, and those are put in definition boxes.

There are also many processes on this page, marked with arrows like ↑ and →. You should know them flexibly apply them to MCQs and DBQs related to this topic. Remember, these processes are used throughout the whole module, so there is no excuse not to know them. You don't have to recite them like you recited the 三字經; if you are familiar with the concepts, they should become 'second nature'.

A drainage basin is, basically, a river system, including the physical land and the water inside.

These words should be recited:

  • A drainage basin (catchment area) is the area occupied by the river system.
  • A watershed is the boundary if a drainage basin. It is determined by the ridge surrounding the system.
  • A confluence point is where tributaries join together.
  • Rivers flow from a point called the source.
  • A tributary is a smaller stream that joins the main river/main stream.
  • Distributaries where when the main river branches out.
  • A mouth is where the main river flows into the ocean.

Here are the inputs, processes and outputs of a drainage basin:

Inputs Processes Outputs
Precipitation, solar energy, weathered materials Erosion, deposition, transportation (infiltration, channel flow) Channel flowing into the sea, runoff, water vapour (in evapotranspiration), sediments (CE90Q20)