The sun's apparent motion across the sky from east to west daily is due to the

This is due to the movement of the Earth: not the Sun is moving, but Earth is moving (this is what  was discussed in the Heliocentic/Geocentric models in middle ages);

the Earth rotates counter-clockwise (as seen from the North Pole) which means that the points on the Earth move relative to the Sun.

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Answer the use of flood plains and irrigation;