Learn from School Connect Online in this chapter we will learn about Water as Water is precious, fundamental and the most essential substances required for the existence of life on earth. Water is found naturally, abundantly on our planet earth.
CBSE Class 6 Science Revision Notes Chapter 14 Water
The different topics covered in CBSE Class 6 Science Chapter 14 are tabulated below:
|14.1||How Much Water Do We Use?|
|14.2||Where Do We Get Water From?|
|14.4||Back To The Oceans|
|14.5||What If It Rains Heavily?|
|14.6||What Happens If It Does Not Rain For A Long Period?|
|14.7||How Can We Conserve Water?|
Ex : 14.1 – How Much Water Do We Use?
- Water makes up a majority of your body weight and is involved in many important functions, including:
- flushing out waste from your body
- regulating body temperature
- helping your brain function
- Water is precious, fundamental and the most essential substances required for the existence of life on earth.
- Water is found naturally, abundantly on our planet earth.
- About two-thirds of the total earth’s surface is covered with water.
- Water is a transparent, odourless and tasteless inorganic molecule composed of hydrogen and oxygen.
Uses of Water
We all use water for different purposes, which includes everyday household uses, including :
for other domestic, irrigating, cultivating the crops and industrial requirements.
Thus, water is required for many activities, therefore it is an essential element required for the continuity of life on the planet.
Ex : 14.2 – Where Do We Get Water From?
Sources of Surface Water :
- Storage Reservoir
Sources of Ground water :
- Open wells
- Tube wells
- Artesian wells
Ex : 14.3 – Water Cycle
- Water cycle is circulation of water through the process of evaporation or condensation as rain or snowfall.
- Water cycle is like a ring.
- In nature, the water cycle takes place from sea to land and back to sea again.
In this process, the water on the earth changes into three different states of matter :
The complete process of the water cycle involves the following process:
1. Evaporation :
- The process of changing water to its vapour form is known as evaporation.
- Evaporation takes place from open surfaces of water all the time—day and night.
- Evaporation of water takes place continuously from oceans, rivers, lakes, wells and soil. Oceans, seas, rivers, lakes, ponds and wells together are often known as water bodies.
- During the day time, sunlight falls on the water in oceans, rivers, lakes. The fields, roads, rooftops and other land areas also receive sunlight. The sunlight also carries heat with it. As a result, water from oceans, rivers, lakes and the soil, and other land areas gets continuously changed into vapour.
- Thus, water vapour gets continuously added to air due to evaporation.
2. Condensation :
- The process of conversion of vapour into liquid form of water is called condensation.
- The process of condensation is opposite to evaporation.
- Cloud formation: The climate close to the earth’s surface is warm. It gets cooled as one goes up in the atmosphere. Water vapour being lighter, rises up in the atmosphere. At the upper layer of atmosphere, where the temperature is lower, the vapour gets condensed into tiny water droplets and forms clouds.
3. Precipitation :
- Clouds carry small droplets of water in them. It may so happen that many droplets of water come together to form larger sized drops of water. Such drops of water may become so heavy that they begin to fall. Falling of water drops is called precipitation.
- Rain: If the water during precipitation remains liquid till it reaches the surface of the earth, we have rains.
- Hail/Snow: Sometimes precipitation may be in the form of hail or snow. Water in a hail or snow is in its frozen or solid form.
- Dew: Many times, especially during winter nights, the air near the surface becomes quite cool. As a result, the water vapour present in it condenses to form water droplets. These water droplets appear as dew.
Ex : 14.4 – Back To The Oceans
Out of 71% of the water on earth, 97% is the water from oceans and seas. Water from oceans and seas contains dissolved salts in it, hence this water is called saltwater or saline water.
- Rainwater falls into rivers, lakes etc.
- The rain droplets fall into oceans, rivers, ponds, seas.
- Water from the rivers, lakes, ponds finally flow into the sea and ocean.
Groundwater: The groundwater is actually rainwater which mainly comes from seepage of water, accumulated under the ground.
Ex : 14.5 – What If It Rains Heavily
In case of continuous rains, the water level of rivers, lakes and ponds will rise. The soil surface will get laden with water resulting in flood. Consequences of flood: When the soil gets too much water, air in the soil comes out of it. Due to lack of air, the animals living inside the soil also come out of it. Heavy rainfall also results in the loss of crops due to flood.
Ex : 14.6 – What Happens If It Does Not Rain For A Long Period?
If it does not rain for a year or more at a place, the soil will lose its water by evaporation and become dry. Water will also be lost through the transpiration process from the plants. Rivers, ponds and wells will dry and the water table would lower down. All this will affect the humans, animals and wild plants. If it continues for one or two years consecutively, it results in drought.
Ex : 14.7 – How Can We Conserve Water?
- It is very important that water should be used carefully. We should take care that water should not get wasted.
- It is not necessary that the water used in the garden is fit for drinking. Yet most often we water the gardens with drinking water supplied by the corporation. We should use water for gardening that has already been used in the kitchen for washing vegetables and fruits, etc.
- Always be careful that the water tank in your house doesn’t overflow when it is being filled.
- Don’t use a hose pipe to wash your car or scooter. Use a bucket instead.
- If you leave the tap running while brushing your teeth, about 16 litres of water get used up. Fill a mug with water and use instead.
Ex : 14.8 – Rainwater Harvesting
- Water harvesting is the activity of collection of rainwater directly by various means.
- Harvested water can either be used immediately or it can be stored for later use.
- In Kerala and Mizoram, where it rains almost the whole year round, small tanks are used to collect rainwater, which drains from rooftops through pipes into these tanks. This water is used directly.
- In a place like Delhi where the monsoon lasts only for 3 months, it is more useful to collect rainwater as groundwater.
Freshwater: Water found in rivers, lakes, and ponds used for domestic and commercial purposes is called fresh water.
Irrigation: Watering crops by artificial means is called irrigation.
Potable water: Water fit for human consumption is called potable water.
Transpiration: The release of water vapour into the atmosphere through the leaves of plants is called transpiration.
Water cycle: The cyclic movement of water from the atmosphere to the Earth and back to the atmosphere through various processes is called the water cycle.
Drought: Abnormally long period of insufficient or no rainfall is called drought.
Famine: Lack of food in a region for a long period is called famine.
Flood: A condition when the ground becomes submerged under water, due to heavy rain and overflowing of rivers is called flood.
Epidemic: A disease affecting thousands of people at the same time is called an epidemic.
Dam: A structure built on a river to store and hold back water is called a dam.
Rainwater harvesting: The process of collecting and storing rainwater from roofs or a surface catchment is called rainwater harvesting.
Conservation of Water : Water management is the effective utilisation of water or managing the water resources carefully.
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