Importance of tides
Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Class 11, Ch 13 "Movements of Ocean Water"
Meaning
Tides follow the positions of the Sun, Moon and Earth, which are known in advance. So tides can be predicted well ahead of time, and navigators and fishermen plan around them. Tides are useful in several ways:
- Navigation: high tide deepens the water, so ships can cross shallow sandbars at river mouths and enter estuary ports.
- Desilting: tides flush silt and polluted water out of estuaries.
- Ecology: mangroves and other plants and animals of the shore depend on the daily rise and fall of the sea.
- Energy: floodgates can trap tidal water and run turbines to make electricity.
Example
Kolkata port (Syama Prasad Mookerjee Port) lies up the Hooghly river in West Bengal. Large ships can reach it only at high tide, and the biggest ships use Haldia port downstream instead.