Page 1 - LN
P. 1

SAI INTERNATIONAL SCHOOL
                         STD VII                                                SUBJECT - GEOGRAPHY
               TOPIC-CH – 5- WATER(LESSON NOTES)

               Sub-topic- Distribution of water bodies

               NOTES- Distribution of water bodies-The distribution of water on the Earth’s surface is
               extremely uneven. Only 3% of water on the surface is fresh; the remaining 97% resides in the
               ocean. Of freshwater, 69% resides in glaciers, 30% underground, and less than 1% is located
               in lakes, rivers, and swamps. Looked at another way, only one percent of the water on the
               Earth’s surface is usable by humans, and 99% of the usable quantity is situated underground.


               Salinity- On average, seawater in the world's oceans has a salinity of approximately 3.5%, or
               35 parts per thousand. This means that for every 1 litre (1000 mL) of seawater there are 35
               grams of salts (mostly, but not entirely, sodium chloride) dissolved in it.


               Although a vast majority of seawater is found in oceans with salinity around 3.5%, seawater is
               not uniformly saline throughout the world.

               WATER CONSERVATION-Water conservation is the careful use and preservation of water
               supply. It includes both the quantity and quality of water utilized. Water is an essential asset
               for the nourishment of all life. Water is definitely the most important natural resources that
               living things need. But at the same time, it has also been misused and wasted.
               Saving WATER really is IMPORTANT!
               Since safe and clean water is limited, people who have access to fresh water. They can take
               steps to control their consumption of water to avoid waste and shortage.
               WORLD WATER DAY- World Water Day, held on 22 March every year since 1993, focuses
               on the importance of freshwater. It is about taking action to tackle the global water crisis.
               World Water Day 2020 is about water and climate change – and how the two are inextricably
               linked.
               OCEAN CIRCULATION-Ocean circulation is the large scale movement of waters in the
               ocean basins.The movements that occur in oceans can be broadly categorised as waves,
               tides and currents.
   1