Answer: the color code is green to red, blue and purple
Explanation: A three hours interval High tides are most represented by blue and purple. Away from the mouth of the Bay, it takes 3 hours for high tide to travel.
The report in the animation relative to the mean lower low water (MLLW) with the color code which indicate high tide is BLUE and PURPLE.
I think it will mean that the words of the question represent the key-words of your thesis. So you mustn't change the words of the question while writing your thesis