Last updated on August 30th, 2023 at 12:57 am
Class 7 Science Chapter 16 Water A Precious Resource Notes
Q: When is World Water Day?
World Water Day is celebrated on 22nd March.
Q: What is the recommended amount of water by the United Nations for daily use?
The recommended amount of water by the United Nations for drinking, washing, cooking, and maintaining proper hygiene is a minimum of 50 litres per person per day.
Q: What is the estimated number of people who could face water scarcity in a few years?
It is estimated that in a few years from now, more than one-third of the people in the world could face water scarcity.
Q: What percentage of the earth’s surface is covered with water?
About 71% of the earth’s surface is covered with water.
Q: What are the different sources of water on earth?
The different sources of water on earth include seas and oceans, rivers, lakes, ice caps, groundwater, and the atmosphere.
Q: What is freshwater and where is it found?
Freshwater is the water that is fit for human consumption directly. It is found in rivers, lakes, underground aquifers, and glaciers.
Q: How does the water cycle maintain the total amount of water on earth?
The water cycle involves the continuous cycling of water among its three forms, which keeps the total amount of water on earth constant even when the whole world is using it.
Q: What is the water supply system in most towns and cities maintained by civic bodies?
The water supply system in most towns and cities is maintained by civic bodies. The water is drawn from nearby lakes, rivers, ponds or wells and is supplied through a network of pipes.
Q: How do people in many villages fetch water?
In many villages, people fetch water directly from sources like wells, tube wells, or hand pumps. Often, they have to walk several kilometres to fetch water.
Q: What is the water table?
The water table is the upper level of the layer below the ground where all the spaces between particles of soil and gaps between rocks are filled with water.
Q: Where does groundwater come from?
Groundwater comes from the water that seeps into the ground from precipitation like rain and snow. It can also come from nearby lakes, rivers, and other water bodies that recharge the groundwater.
Q: What is the process of seeping of water into the ground called?
The process of seeping of water into the ground is called infiltration.
Q: What is an aquifer?
An aquifer is a layer of hard rock below the water table where groundwater is stored.
Q: How is water in the aquifers usually pumped out?
Water in the aquifers is usually pumped out with the help of tube wells or handpumps.
Q: Can we keep on drawing water from under the ground? How will it affect the water table?
Drawing too much water from under the ground can cause the water table to drop, making it harder to pump water out. It can also cause wells and handpumps to dry up. Therefore, it is important to use groundwater sustainably and conserve it for future generations.
Q: What is the impact of human activities on the water table?
The impact of human activities on the water table is significant. Increase in population, industrial and agricultural activities, and deforestation are some common factors that can deplete the water table.
Q: What are the factors that can deplete the water table?
Factors that can deplete the water table include increase in human activities, decrease in rainfall, and decrease in the effective area for seepage of water due to deforestation.
Q: How is the water table replenished?
The water table is replenished through the process of seepage of rainwater and water from other sources such as rivers and ponds, which seeps through the soil and fills the empty spaces and cracks deep below the ground. This process is called infiltration.
Q: How does increasing population affect the seepage of rainwater into the ground?
Increasing population leads to the construction of more houses, shops, offices, roads, and pavements. This results in a decrease in open areas like parks and playgrounds, which reduces the seepage of rainwater into the ground.
Q: Why is groundwater depletion happening in many cities?
Groundwater depletion is happening in many cities due to factors like increasing population, industrial and agricultural activities, deforestation, and scanty rainfall. These factors reduce the amount of water that seeps into the ground, and as a result, the water table goes down.
Q: Why is water required for construction work and how does it affect the water table?
Water is required for construction work for activities like mixing concrete, curing, and dust suppression. Often, groundwater is used for this purpose. When groundwater is extracted for construction work and not sufficiently replenished, it affects the water table and leads to its depletion.
Q: Why is groundwater used by industries?
Groundwater is used by industries because it is a cheap and easily available source of water. Industries use water for various purposes like cooling, cleaning, and manufacturing processes. However, the excessive and indiscriminate use of groundwater by industries can lead to depletion of the water table.
Q: What is the reason for depletion of water table in agriculture?
Population pressure on agriculture forces increasing use of groundwater day by day, leading to depletion of water table.
Q: Why does the distribution of water over the globe vary?
The distribution of water over the globe is quite uneven due to a number of factors, including differences in rainfall and the presence of deserts.
Q: What are the consequences of excessive rains and absence of rains in different regions of India?
Excessive rains cause floods, whereas the absence of rains results in droughts. Therefore, some regions in India may have floods while others may suffer from droughts at the same time.
Q: What is the responsibility of civic authorities in preventing water wastage through pipes?
Ans: The civic authorities are responsible for preventing the wastage of precious water through well-planned pipe systems. They should ensure that water supply pipes do not leak and cause huge water wastage.
Q: What is water harvesting or rainwater harvesting?
Ans: Water harvesting or rainwater harvesting is the process of collecting and storing rainwater to recharge the groundwater. It is a way of conserving water, especially in areas with low rainfall.
Q: What is drip irrigation?
Ans: Drip irrigation is a technique of watering plants by making use of narrow tubings which deliver water directly at the base of the plant. It is a water-saving method of irrigation that ensures efficient use of water in agriculture.
