Oceanography (2+1)

Tidal Currents

Tidal Currents

The tides horizontal and vertical flow of water is easily noticeable near the coast. The periodical horizontal movements of the sea, in response to the tide generating forces, are called tidal currents. These currents respond to the changes in the tide-generating forces brought about by the changing relative positions of the moon, the sun and the earth, in a manner similar to that tides. High tides and low tides can set up currents known as flood currents and ebb currents, particularly in narrow straits and channels. In these areas tidal currents may reach velocities of up to 15km/h. Similar to tides, tidal currents in restricted areas changes their direction due to earth’s rotation. Some time the flood and ebb currents may even be opposite to each other. The important factors which affect the tidal currents are the shape of the bay, river flow, depth and shape of the channel and friction. Tidal currents in estuaries and restricted channels can be very important. They can move large amount of sediment, which may block horbours located in the estuaries.