Explain the factors responsible for the depletion of water table.
Some of the factors which affect the water table at a place and make it go falling down are as follows:
1. Increasing Population: The increasing population needs water in the higher proportion for its day full activities. As the population is increasing, more houses, shops, offices, schools, industries, roads and pavements, etc. need to be built and for this huge amount of water is required. Usually, groundwater is consumed for constructed work and this decreases the seepage of rain water from the ground. So, due to increasing population, we are consuming more groundwater and on the other hand we are allowing less rainwater to go into the ground. This leads to the depletion of water table.
2. Increasing Industries: Industries produce a large number of numerous things that we use in our everyday life. Almost everything that is made in industries needs water at some stage during the production, due to which water level is decreasing day by day. As the population is increasing, the demand for various industrial goods are increasing and hence the number of industries are also increasing simultaneously. Water used by most of the industries is drawn out from the ground which results in depletion of water table.
3. Scanty Rainfall: ‘Insufficient rainfall’ is called ‘scanty rainfall’ that means is not enough. Sometimes scanty rainfall occurs during the rainy season. Since there is less rainfall, less rainfall goes into the ground. In such a situation, much more groundwater is drawn out by the people for various purpose than gets replenished by rainfall. This leads to depletion in water table or level.
4. Deforestation: The cutting down of trees and plants from the forest for various purposes (like for the industrial area) is called deforestation. We know that forest help in bringing rain by making the air cooler and with the higher transpiration rate. So lower number of trees and plants in the forests will bring less rainfall. So, deforestation leads to lesser rainfall as well as lesser seepage of rainfall into the ground.
5. Decreases in Effective Area for Seepage of Rainfall: Due to increasing population, urbanisation and industrialisation, more and more space is being covered by houses, other buildings, roads etc. The open spaces having unpaved ground are getting reduced on the daily basis. It is the ‘unpaved ground’ which lets the rainwater seeps into the ground and recharges the groundwater table. Since, the effective area for seepage of rainwater in urban areas is decreasing day by day, less and then less rainwater seeps into the ground which leads to the depletion of water table.
Make a sketch showing groundwater and water table. Label it.
There are ten tubewells in a lane of fifty houses. What could be the long term impact on the water table?
Explain how groundwater is recharged?
You have been asked to maintain a garden. How will you minimise the use of water?
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world. (T/F)
(b) Water shortage is a problem faced only by people living in rural areas. (T/F)
(c) Water from rivers is the only source for irrigation in the fields. (T/F)
(d) Rain is the ultimate source of water. (T/F)
Fill in the blanks with the appropriate answers:
(a) People obtain groundwater through________ and ________. (b) Three forms of water are ________, ________ and ________.
(c) The water bearing layer of the earth is ________.
(d) The process of water seepage into the ground is called ________.
Choose the correct option. The total water
(i) in the lakes and rivers of the world remains constant.
(ii) under the ground remains constant.
(iii) in the seas and oceans of the world remains constant.
(iv) of the world remains constant.
Which one of the following is not responsbile for water shortage?
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall
(iv) Mismanagement of water resources
State similarities and differences between the laboratory thermometer and the clinical thermometer.
State differences between acids and bases.
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food
Name the elements that determine the weather of a place.
Fill the missing word in the blank spaces in the following statements:
(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———.
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
Why does an athlete breathe faster and deeper than usual after finishing the race?
Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
(e) Synthesis of carbohydrates
Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called_____________.
(b) A flower may have either male or female reproductive parts. Such a flower is called_____________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _____________.
(d) The fusion of male and female gametes is termed as _____________.
(e) Seed dispersal takes place by means of _____________, _____________ and _____________.
Classify the following as motion along a straight line, circular or oscillatory motion:
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.
State two experiences that made you think that air exerts pressure (other than those given in the text).
Explain what you understand by sexual reproduction.
A wooden spoon is dipped in a cup of ice cream. Its other end
(a) becomes cold by the process of conduction.
(b) becomes cold by the process of convection.
(c) becomes cold by the process of radiation.
(d) does not become cold.
Mark ëTí if the statement is true and ëFí if it is false:
(i) During heavy exercise the breathing rate of a person slows down. (T/F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
(iv) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
What is sludge? Explain how it is treated.
Match the items given in Column I with one or more items of Column II.
Column I Column II
(a) A plane mirror (i) Used as a magnifying glass.
(b) A convex mirror (ii) Can form image of objects spread over a large area.
(c) A convex lens (iii) Used by dentists to see enlarged image of teeth.
(d) A concave mirror (iv) The image is always inverted and magnified. (e) A concave lens (v) The image is erect and of the same size as the object.
(vi) The image is erect and smaller in size than the object.
State two differences between a convex and a concave lens.
One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be
(a) 80°C (b) more than 50°C but less than 80°C
(c) 20°C (d) between 30°C and 50°C
An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both.