CBSE Class 7 Science Chapter 16 Notes Water: A Precious Resource
Water: A Precious Resource Class 7 Notes Understanding the Lesson
1. Water is the most important compound for all living things. There can be no life without it.
2. 22 March is celebrated as the world water day to attract the attention of everybody towards the importance of conserving water.
3. Water is an universal solvent.
4. 71% of earth surface is covered with water.
5. Three forms of water are solid, liquid and gas.
6. The water on the earth has been maintained for millions of years by various processes which make the water cycle.
7. The solid form of water, snow and ice, is present as ice caps at the poles of the earth, snow-covered mountains and glaciers.
8. Liquid water is present in oceans, lakes, rivers and even underground.
9. The gaseous form of water is the water vapour which is present in the air around us.
10. The rainwater or the water from other sources like ponds, lakes, etc., percolates under the ground and collects over the impermeable rocks. This water is called
11. The upper limit of underground water is called water table. The water table varies from place to place, and it may even change at a given place.
12. The process of seeping of water into the ground is called The groundwater gets charged by this process.
13. Aquifer is a water trap where groundwater is trapped between the layers of hard rock below water table.
14. Following are the causes of water shortage:
- Increasing population
- Rapid growth of industries
- Growing irrigation requirements
- Increasing agricultural activities
- Mismanagement
15. The distribution of water is also quite uneven due to number of factors. There are some regions in our country may have floods while others may suffer droughts at the same time.
16. Water management should be done by following ways:
17. Unnecessary use of water and overdrawing of groundwater should be stopped.
18. Recharge of groundwater must be increased through various processes.
19. We should prevent the wastage of water during its supply through pipes, the leaking taps in buildings and other places.
20. Plants wilt and ultimately dry-up if they are not watered for few days.
Class 7 Science Chapter 16 Notes Important Terms
Aquifer: A water trap where groundwater is trapped between the layers of hard rock below water table.
Depletion: Depletion is reduction in number or quantity of something. Rapid growth of industries, increasing population, growing irrigation requirements and mismanagement are some of the causes for water depletion.
Drip irrigation: It is a technique of irrigation by using narrow tubings which deliver water drop by drop directly at the base of the plant.
Groundwater: The water that seeps into the earth, gets collected between the layers of rocks and found below the water table is called groundwater.
Infiltration: The process of seeping of water into the ground is called infiltration. The groundwater gets recharged by this process.
Water harvesting: The water harvesting simply involves collection of rainwater from surfaces that can be used to recharge the groundwater or storing it for later use.
Water table: The water present deep under the ground is known as groundwater and the upper limit of this layer is known as water table.