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.
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
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
Sketch the cross section of soil and label the various layers.
Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body
Down
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
Sketch the reproductive parts of a flower.
Solve the following crossword puzzle with the clues given:
Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
Describe how crystals of copper sulphate are prepared.
Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
(ii) Upper layer of the soil (b) All kinds of soil
(iii) Sandy soil (c) Dark in colour
(iv) Middle layer of the soil (d) Small particles and packed tight (v) Clayey soil (e) Lesser amount of humus
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
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.
State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
(a) Cutting a log of wood into pieces is a chemical change. (True/False)
(b) Formation of manure from leaves is a physical change. (True/False) (c) Iron pipes coated with zinc do not get rusted easily. (True/False)
(d) Iron and rust are the same substances. (True/False)
(e) Condensation of steam is not a chemical change. (True/False)
The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear view mirror the
image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
(i) 1 m/s (ii) 2 m/s
(iii) 4 m/s (iv) 8 m/s
Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair (ii) Stomata (iii) Leaf veins (iv) Sepals
Which of the following statements is not correct?
(i) Forests protect the soil from erosion.
(ii) Plants and animals in a forest are not depedent on one another.
(iii) Forests influence the climate and water cycle.
(iv) Soil helps forests to grow and regenerate
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
Show with the help of a sketch that the plants are the ultimate source of food.
Why do we get instant energy from glucose?
Explain what you understand by sexual reproduction.