Water: A Precious Resource
IMPORTANT TERMS
Aquifer Water reservoir formed above the impervious layers of rock; Underground water is also known as an aquifer.
Infiltration The process of seeping of surface water into the ground is called Infiltration.
Water Table The top level of the underground water is called the water table.
Surface Water Water present on the surface of the Earth is known as Surface water.
Groundwater Water that lies beneath the surface of the Earth is called underground water.
Bawris Deep step-wells built during olden times for the storage of rain water.
Hard Water Water that contains dissolved salts of calcium and magnesium.
Potable Water The water suitable for drinking by living beings is known as potable water.
FORMS OF WATER
Water exists in three forms: Solid, Liquid and Gas.
Solid - Snow, icebergs, glaciers and hail are solid forms of water.
Liquid - Dew, rain and water droplets are liquid forms of water.
Gaseous - Water vapour, steam, clouds and fog are gaseous forms of water.
WATER AVAILABLE FOR USE
Water covers about three-fourth (about 71%) of the Earth's surface.
Approximately 97 percent of the water on Earth is salt water. The water in the seas and oceans is so salty that it cannot be used for drinking or other purposes.
Roughly, a very small faction (about 3%) of the water found on the Earth is available to us as freshwater. Out of which, 2.997% is frozen in the glaciers and in the polar ice caps and is not readily available. So, the percentage of water available on Earth for use by human beings is about 0.006%.
About 60% of the population of India depends on agriculture for their living. About 20-22% of water is used by industries and about 8% is used for domestic activities.
WATER CYCLE
Water cycle is a continuous circulation of water where water evaporates from the surface of the Earth, form clouds and falls on the surface of Earth as precipitation.
Evaporation - Evaporation is the process in which liquid state changes to a gaseous state due to an increase in temperature or pressure. It is a part of the water cycle. During this process, the heat of the sun changes the water in oceans, rivers and other water bodies into water vapour.
Condensation - It is the process by which water vapour is changed back into liquid water. Condensation is very important to our weather as it is responsible for cloud formation. As water vapour rises into the atmosphere, it mixes up with very tiny particles of dust present in the atmosphere to form tiny droplets or ice crystals, if it is very cold. As more and more water particles and dust particles stick together, clouds are formed.
Precipitation - Precipitation occurs when the water drops become too heavy to float in the air, they fall on the Earth in the form of rain, hail or snow. Water stored in the clouds reaches Earth in the form of rain. It comes in the form of ice crystals or snow, if it is very cold.
SOURCES OF WATER
The main sources of water on Earth are rainwater, surface water and groundwater.
Rainwater
Rainwater is one of the main sources of water. It is the purest form of water. The rainwater becomes a part of a water body such as ocean, river or lakes (surface water) or it seeps into the ground (underground water).
Surface Water
Water present on the surface of the Earth is known as Surface water.
Rivers, ponds and lakes, streams, oceans and seas are sources of surface water. The water in the water bodies comes mainly from rainfall or melting of glaciers.
Groundwater
Groundwater is the water present under the ground where the soil is completely filled with water. The moisture in the soil indicates the presence of water underground.
The upper layer of underground water where all the space between particles of soil and rocks is filled with water is called water table.
At some places the groundwater is stored between layers of hard rock below the water table, which is known as an aquifer.
The process of seeping of water from various sources such as rivers and ponds into the ground is known as infiltration. The groundwater gets recharged by this process. Water drawn from under the ground also gets replenished by seepage of rainwater.
Water in the aquifers can be obtained through hand pumps and tube wells. Wells can also be drilled to take out underground water.
HARD WATER AND SOFT WATER
Water is regarded as hard or soft based on the presence of certain mineral salts.
When hard water is treated with soap, an insoluble and sticky substance called scum is formed, and it does not lather therefore, hard water is not considered suitable for washing clothes.
Hard water usually contains dissolved salts such as sulphates, chlorides and bicarbonates of calcium and magnesium.
Calcium and magnesium bicarbonates cause temporary hardness in water which can be removed by boiling.
The presence of chlorides and sulphates of calcium and magnesium in water cause permanent hardness. Permanent hardness of water can be removed by treating it with Sodium carbonate (washing soda).
Soft water is the water which has relatively low concentration of calcium carbonate and other ions. It produces good lather with soap.
CONSUMPTIVE AND NON-CONSUMPTIVE USE OF WATER
Consumptive use of water occurs when the water is removed from available supplies without returning to a water resource system such as rivers, ponds etc. Water used in manufacturing, agriculture, and household activities is a consumptive use of water.
Water used for navigation and Hydropower generation is considered as non-consumptive use of water as water does not get consumed in these activities. It merely facilitates the activities.
SCARCITY OF WATER
The major reasons for the scarcity of water are the following:-
Agricultural activities
India is a country which depends mainly on agriculture. Agricultural activities demand maximum amount of water. Irregular rainfall has increased the consumption of groundwater. Sometimes rainfall is not sufficient to water the crops, so the farmers have to use groundwater for irrigation.
Increasing Population
Growing population is one of the main reasons for the depletion of water table in India. Demand of water has increased because of the rapid increase in population. As the population increases, the demand for houses, shops etc. also increases. A large amount of water is needed for constructing houses because of which the water table depletes.
Industrial Activities
Rapid increase in the number of industries has led to scarcity of water. All industries depend on water at some level of production. Water is used by all the industries and it is obtained from the ground water, which depletes the water table.
Deforestation
Deforestation leads to decrease in the number of trees. As trees have the ability to hold water, but because of deforestation, the water keeps flowing towards the sea and the groundwater is not recharged.
Water Pollution
Water pollution is also reason for the scarcity of water. Most of the rivers in our country and other sources of fresh water are polluted by industrial wastes or effluents. Industrial wastes discharged into the water bodies contain a lot of toxic substances that pollute the water and make it unfit for drinking.
Use of Borewell Technology
Borewells are basically vertical drilled wells, bored into an underground aquifer in the Earth’s surface, to extract water for various purposes. Excessive drilling of borewells has led to exploitation of groundwater at higher rates than the rate of water recharge and caused depletion of the groundwater levels.
CONSERVATION OF WATER
Avoiding wastage of water and using it economically and judiciously by following water saving practices can help in conserving the water.
Rainwater Harvesting
Rainwater harvesting is the process of collecting and storing rainwater that collects on roofs instead of letting it go down the drain. It is one of the ways to conserve water.
Fixing Leaky Taps
A lot of water is wasted through leaking taps. So the leaking taps must always be fixed to avoid wastage of water.
Improving the methods of Irrigation
Water can be conserved by improving the methods of irrigation. Drip system is the most efficient method for irrigation because there is no wastage of water. In this system water falls drop by drop directly at the base of each plant through a network of pipes.
Water can also be conserved by building dams, reservoirs and embankments.
FUNCTIONS OF WATER IN BODY
Water is very important for the proper functioning of the human body. It plays an important role in the process of respiration, digestion, metabolism, and excretion.
Water helps in regulating the body temperature.
It helps in digestion of food.
It helps in removing the waste produced in the body.
It helps in carrying nutritive elements to the tissues.
INTERESTING FACTS
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