Q30. Why the quality of water is deteriorating?
of water is deteriorating because
River water, which is our primary source of
water, gets contaminated due to various reasons such as direct disposal of
sewage by municipalities, excessive discharge of industrial pollutants, use for
daily chores like washing, bathing, livestock bathing, garbage disposal, etc.
Water sourced from groundwater too has
deteriorated due to the excessive use of pesticides & insecticides in
agriculture, which seep into the groundwater as well as get washed away into
Q31. Write a short note on Tsunami?
i. Tsunami is a Japanese word that means
“Harbour waves” as the harbours get destroyed whenever there is tsunami.
An earthquake, a volcanic eruption or
underwater landslides can shift large amounts of ocean water.
As a result a huge tidal wave called
tsunami, that may be as high as 15m., is formed. The largest tsunami ever
measured was 150m. high. These waves travel at a speed of more than 700 km. per
The tsunami of 2004 caused wide spread
damage in the coastal areas of India. The Indira point in the Andaman and
Nicobar islands got submerged after the tsunami.
Q32. Write a short note on ocean currents?
Ocean currents are streams of water flowing
constantly on the ocean surface in definite directions.
The ocean currents may be warm or cold.
Generally, the warm ocean currents originate near the equator and move towards
the poles. The cold currents carry water from polar or higher latitudes to
tropical or lower latitudes. The Labrador Ocean current is cold current while
the Gulf Stream is a warm current.
The ocean current influence the temperature
conditions of the area. Warm currents bring about warm temperature over land
surface. The areas where the warm and cold currents meet provide the best
fishing grounds of the world. Seas around Japan and the eastern coast of North
America are such examples. The areas where a warm and cold current meet also
experience foggy weather making it difficult for navigation.
Q33. What are the major movements of ocean water?
movements that occur in oceans can be broadly categorised as: waves, tides and
When the water on the surface of the ocean rises and falls alternately, they
are called waves. Waves are formed when winds scrape across
the ocean surface. The stronger the wind blows, the bigger the wave becomes.
The rhythmic rise and fall of ocean water twice in a day is called a tide. It
is high tide when water covers much of the shore by rising to its highest level.
It is low tide when water falls to its lowest level and recedes from the shore.
strong gravitational pull exerted by the sun and the moon on the earth’s
surface causes the tides.
Currents - Ocean currents are streams of water flowing
constantly on the ocean surface in definite directions. The ocean currents may
be warm or cold. Generally, the warm ocean currents originate near the equator and
move towards the poles. The cold currents carry water from polar or higher
latitudes to tropical or lower latitudes. The Labrador Ocean current is cold
current while the Gulf Stream is a warm current.