Student or Learner
There are two channels. Water can go through the cross-section between the channels, as shown in figure. But I don't know how to call it in English.
Any help will be appreciated.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
Are you sure it doesn't raise or lower to control the volume of water? I can't tell for sure from the picture, but it looks like a flow gate or sluice gate as Barb suggested.
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Johny, you should know by now that you have to say you are not a teacher when answering questions.