Indicating coincidence of high tides or low tides.
Relating to a line that passes through each location on a coastal map where tides occur at the same time of day. Cotidal maps show variation in the height of the tides and indicate the time of high tide occurrence. Cotidal charts can be made using tide gauge data from gauges at regular intervals along the coast; however, computer modeling is increasingly used, especially where the tides vary greatly over a short distance.
[koh-tahyd-l] 
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