Answer:
Because channels are the easiest way to transport water from one place to another.
Explanation:
In a way, channels are just like small, artificial rivers that humans have built since the dawn of civilization in order to take water from the source, to crops that are located further away from that source.
Irrigation channels have allowed civilizations to grow crops in areas where water resources are not so readily available, by relying on a single large water source. This is why all early civilizations developed around major rivers, and built irrigation channels that took water from those rivers to the many other agricultural regions.
