Water a Precious Resource CBSE Class 7 Science

Key and Important notes of Water a precious Resource
 
World Water Day: 22 March is celebrated as World Water day. It's purpose is to attract the attention of everybody towards the Importance of conserving water.

Minimum Required Water: According to Research b y United Nations, each individual requires about 50 litres of water per day to go through daily tasks



Water Scarcity: This situation arises when the demand for water is much more than supply. It is estimated that in few years from now more than one third of the people in the world could face water scarcity.

Potable Water: The water which is considered fit for human consumption is referred to as potable water.It is also known as fresh water

Source of Freshwater: Most of the freshwater is in the frozen form and is found in glaciers other sources of fresh water are ponds, lakes, underground water and rivers, springs etc
Saline Water: The water in seas and oceans contain huge concentration of salts and compounds therefore it is not fit for drinking

Forms of Water: The solid form, snow and ice, is present as ice caps at the poles of the earth, snow-covered mountains and glaciers. Liquid water is present in oceans, lakes, rivers, and even underground. The gaseous form is the water vapour present in the air around us. The continuous cycling of water among its three forms keeps the total amount of water on the earth constant even when the whole world is using it.


Supply of Water in Towns or urban Centres
The water supply system in cities is maintained by Civic bodies, where the water is drawn from nearby lakes, rivers, ponds or wells, and is supplied through a network of pipes.

Villages do not have such a water supply system. there people fetch water directly from sources Problem faced by Village folk
Women and children have to walk several kilometres to fetch water The children suffer a lot, and are unable to attend school as they spend hours fetching water

Water Table:The upper limit of level where all the space between particles of soil and gaps between rocks are filled with water is called the water table

Ground water: It is the water that seeps into the ground through soil and fills the empty spaces and cracks deep below the ground, and at places the ground water is stored between layes of hard rock below the water table. This is known as aquifer.
The process of seeping of water into the ground is called infiltration. the ground water gets recharged by the process of infiltration

Various causes of Water Table Depletion
(i) Increase population decreases open areas which decreases seepage of rainwater.
(ii) Increasing industries more water is drawn out from ground.
(iii) Agricultural activities irrigation systems fail due to erratic rainfall which results in increased used of ground water.
(iv) Uneven distribution of rainfall.
(v) Scanty rainfall.
(vi) Deforestation.


Uneven Distribution of Water India is a vast country and the rainfall is not the sam everywhere. some region have excessive rains while some others have very little rainfall. Excessive rains cause floods, whereas the absence of rains results in droughts. therefore some regions in our country may have floods while others may suffer from droughts at the same time

Causes of Water Wastage
Leakage in the supply lines
Mismanagement at level of individuals

Ways of conserving water
Rainwater Harvesting: Rainwater harvesting is a technique used for collecting, storing and using rainwater for landscape irrigation and other uses. The rainwater is collected from various hard surfaces such as rooftops and/or other man made above ground hard surfaces.

Drip irrigation is a form of irrigation that saves water and fertilizer by allowing water to drip slowly to the roots of many different plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters. 

Water Wise Habits
1.Turn off taps while brushing
2.Mop the floor instead of washing
Effects of Water Scarcity on Plants

Plants wilt and ultimately dry up if they do not get water even for a few days. plants need water to get nutrients from the soil to prefer their food.

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