Learn from School Connect Online in this chapter ” Water”. Water is a vital and invaluable resource that plays a fundamental role in supporting life on Earth. It is one of the most essential substances required for the existence of living organisms and is abundantly available in its natural form across our planet.
Its abundance and availability make it a critical element in shaping the planet’s ecosystem, climate, and weather patterns. Thus, water is not only precious but also indispensable for the sustainability of life on 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? |
| 14.3 | Water Cycle |
| 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? |
| 14.8 | Rainwater Harvesting. |
Ex : 14.1 – How Much Water Do We Use?
Water is an indispensable element that constitutes a significant portion of our body weight and is involved in crucial functions, including flushing out waste, regulating body temperature, and supporting brain function.
As a fundamental and precious resource, water is abundantly found in its natural form on Earth, covering about two-thirds of the planet’s surface. It is a transparent, odorless, and tasteless inorganic molecule composed of hydrogen and oxygen, which makes it essential for the existence of life on our planet. Its natural abundance and properties make it a vital component in shaping the Earth’s ecosystem, climate, and weather patterns.
Uses of Water
Water serves a myriad of purposes in our daily lives, ranging from household uses to industrial requirements. These include essential activities such as drinking, cooking, cleaning, washing, bathing, as well as domestic, irrigation, and crop cultivation needs.
Water’s versatility and significance in various aspects of human activities make it an indispensable element for the continuity of life on our planet. It plays a critical role in meeting our basic needs, supporting agricultural practices for food production, and facilitating industrial processes that are essential for modern life. Thus, water’s multifaceted importance underscores its status as an essential resource for sustaining life and human civilization.
Ex : 14.2 – Where Do We Get Water From?
Sources of Surface Water :
- Lakes
- Ponds
- Streams
- Rivers
- Storage Reservoir
Sources of Ground water :
- Open wells
- Tube wells
- Artesian wells
- Springs
- Infiltration
Ex : 14.3 – Water Cycle
The water cycle, also known as the hydrological cycle, is a continuous process of water circulation through various stages, including evaporation, condensation, and precipitation in the form of rain or snowfall.
The water cycle can be visualized as a ring, where water evaporates from the Earth’s surface, rises into the atmosphere, and then condenses into clouds. These clouds release water in the form of precipitation, which falls back to the Earth’s surface as rain or snow. The water then replenishes various water bodies on land, such as rivers, lakes, and groundwater, before eventually flowing back into the oceans, thus completing the cycle.
Throughout the water cycle, water can exist in three different states of matter: solid (such as ice or snow), liquid (such as rain or surface water), and gas (such as water vapor in the atmosphere). These changes in state are driven by factors such as temperature, pressure, and humidity, and are crucial for the continuous movement and recycling of water on Earth, which is vital for maintaining the water balance and supporting life on our planet.
The complete process of the water cycle involves the following process:
1. Evaporation :
Evaporation is the process of water changing into its vapor form, which occurs from the open surfaces of water bodies, such as oceans, rivers, lakes, wells, and soil, both during the day and night.
Water bodies, including oceans, seas, rivers, lakes, ponds, and wells, constantly undergo evaporation, as they receive sunlight during the day. Sunlight carries heat, which causes water from these bodies and land areas, such as fields, roads, and rooftops, to continuously transform into vapor.
As a result, water vapor is continuously added to the air through evaporation, contributing to the water cycle and the movement of water in the environment. This process plays a crucial role in regulating the Earth’s water balance and maintaining the availability of water for various natural processes and human activities.
2. Condensation :
Condensation is the process of water vapor changing into its liquid form, which is opposite to evaporation.
Cloud formation occurs due to the temperature changes in the atmosphere. The climate near the Earth’s surface is generally warm, but as one ascends higher in the atmosphere, the temperature decreases. Water vapor, being lighter, rises in the atmosphere.
When it reaches the upper layers where the temperature is lower, the water vapor condenses into tiny water droplets, forming clouds. These clouds are visible masses of water droplets suspended in the air, and they play a significant role in the Earth’s weather and climate patterns.
3. Precipitation :
Clouds contain small droplets of water, which can come together and form larger water droplets. These larger droplets may become heavy enough to fall, which is known as precipitation.
Rain occurs when the water droplets remain in a liquid state until they reach the Earth’s surface during precipitation.
Hail/Snow are other forms of precipitation where water is in its frozen or solid state.
Dew is formed when the air near the Earth’s surface becomes cool, especially during winter nights. The water vapor in the air condenses into water droplets, which appear as dew.
Precipitation, whether in the form of rain, hail, snow, or dew, plays a vital role in the water cycle and has significant impacts on weather patterns, ecosystems, and human activities.
Ex : 14.4 – Back To The Oceans
Out of the total water on Earth, about 71% is in the form of water bodies such as oceans and seas. Water from oceans and seas is known as saltwater or saline water as it contains dissolved salts.
Rainwater, which falls from the clouds during precipitation, replenishes rivers, lakes, and ponds.
The rain droplets that fall onto the Earth’s surface may flow into oceans, rivers, ponds, and seas.
Water from rivers, lakes, and ponds eventually flows into the sea and ocean, completing the water cycle.
Groundwater, on the other hand, is the water that accumulates under the ground through seepage of rainwater. It is an important source of water for various purposes and plays a crucial role in supporting ecosystems and human activities.
Ex : 14.5 – What If It Rains Heavily
During prolonged periods of heavy rainfall, the water levels of rivers, lakes, and ponds may rise, leading to potential flooding. Floods can have several consequences, including:
Soil saturation: Excessive water can saturate the soil, leading to the expulsion of air from the soil. This lack of air can force animals that reside in the soil to come out of it.
Crop loss: Floods can cause significant damage to crops, resulting in crop loss. The inundation of fields with water for prolonged periods can lead to crop damage, reduced yield, or even complete loss of crops.
Displacement of animals: Floods can disrupt the natural habitats of animals, causing them to flee from their usual dwelling places in search of higher ground, food, and safety.
Disruption of infrastructure: Floods can damage infrastructure such as roads, bridges, buildings, and other structures, leading to disruption of transportation, communication, and utilities.
Economic and social impacts: Floods can have significant economic and social impacts, including loss of property, displacement of people, disruption of livelihoods, and increased costs for recovery and rehabilitation efforts.
Ex : 14.6 – What Happens If It Does Not Rain For A Long Period?
In the absence of rainfall for an extended period, typically a year or more, the soil may lose its moisture through evaporation, and the water stored in rivers, ponds, and wells may diminish. Additionally, the transpiration process from plants can also lead to water loss. As a result, the water table may decline, impacting humans, animals, and wild plants.
If this situation persists for consecutive years, it can result in a drought, which can have severe consequences for the environment, agriculture, livestock, and local communities.
Ex : 14.7 – How Can We Conserve Water?
- It is crucial to use water wisely and avoid wastage.
- Water used for gardening does not necessarily need to be fit for drinking. Instead of using drinking water supplied by the corporation, we can utilize water that has already been used in the kitchen for washing vegetables and fruits.
- When filling the water tank in your house, ensure that it does not overflow.
- Avoid using a hosepipe to wash your car or scooter, and opt for a bucket instead.
- Leaving the tap running while brushing your teeth can consume around 16 litres of water. To conserve water, fill a mug with water and use it instead of letting the tap run.
Ex : 14.8 – Rainwater Harvesting
- Water harvesting is the process of collecting rainwater through various methods.
- Harvested rainwater can be utilized immediately or stored for future use.
- In regions like Kerala and Mizoram where rainfall is abundant throughout the year, small tanks are used to collect rainwater from rooftops through pipes, which is then used directly.
- In contrast, in places like Delhi where the monsoon season lasts only for three months, rainwater harvesting is more beneficial for replenishing groundwater levels.
Conclusion :
Freshwater refers to water found in rivers, lakes, and ponds that is suitable for domestic and commercial use. Irrigation is the artificial process of watering crops to support their growth. Potable water is safe for human consumption. Transpiration is the release of water vapor into the atmosphere through plant leaves. The water cycle is the continuous movement of water from the atmosphere to the Earth’s surface and back through various processes.
Drought is an extended period of inadequate rainfall, while famine is a severe shortage of food in a region over a prolonged time. Flood occurs when heavy rainfall or overflowing rivers submerge the ground. An epidemic is a widespread occurrence of a disease that affects a large number of people.
A dam is a constructed structure on a river designed to store and control water. Rainwater harvesting is the process of collecting and storing rainwater from rooftops or other surface catchments. Conservation of water involves managing water resources carefully to ensure effective utilization and sustainability.
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