Science 5 Marks Questions

The factors responsible for the depletion of water table are as follows:

1. Increasing population:

As a result of increasing population, all the facilities such as houses, shops, roads, offices, pavements, etc. increase to fulfill the increasing demands. This, in turn, decreases the open area for seepage of water into the ground.

2. Increasing industries:

Most of the stages of manufacturing processes in industries require water. If the number of industries increases, then the water required by them will also increase. Therefore, increase of industries contributes to the depletion of water table.

3. Agricultural activities:

India is an agricultural country and agriculture is impossible without water. The water for agriculture is mainly utilised from ground water, rain water and canal water. As there is no rainfall in many places, agriculture cannot be entirely depended on rain water. Also, canal water is available in a few places only. Therefore, ground water is the main source of water for agricultural activities and this causes depletion of water table.

The wells, tubewells and handpumps are main sources of water for many people. The water in these sources is the groundwater. It is upper level of underground water which occupies all the spaces in the soil and rocks and form a water table as shown in the figure below:
The upper limit of groundwater is called water table. It represents the depth of water filled area at a given place. The water table rises and falls depending upon the amount of rainwater that seeps into the groundwater and how much groundwater is drawn out for irrigation and industry. The seeping down of rainwater into the groundwater is called infiltration. The groundwater, thus gets recharged by this process. At some places, the groundwater is stored between layers of hard rock below the water table. This is aquifer which contains the groundwater usable by tubewells and handpumps. These sources however, have limited sources of water and may get exhausted if used excessively.

There are six important processes that make up the water cycle:

1. Condensation: The opposite of evaporation. Condensation occurs when a gas is changed into a liquid.
2. Infiltration: Infiltration is an important process where rain water soaks into the ground, through the soil and underlying rock layers.
3. Runoff: Much of the water that returns to Earth as precipitation runs off the surface of the land, and flows downhill into streams, rivers, ponds and lakes.
4. Evaporation: The process where a liquid, in this case water, changes from its liquid state to a gaseous state.
5. Precipitation: When the temperature and atmospheric pressure are right, the small droplets of water in clouds form larger droplets and precipitation occurs. The raindrops fall to Earth.
6. Transpiration: As plants absorb water from the soil, the water moves from the roots through the stems to the leaves. Once the water reaches the leaves, some of it evaporates from the leaves, adding to the amount of water vapour in the air. This process of evaporation through plant leaves is called transpiration.

• Increasing population: decreases open areas which decreases seepage of rainwater.
• Increasing industries: more water is drawn out from ground.
• Agricultural activities: irrigation systems fail due to erratic rainfall which results in increased use of groundwater.
• Uneven distribution of rainfall.
• Scanty rainfall.
• Deforestation.

1. Sachin has build up cemented drainage channels in the elevated area and tanks where these channels will collect water.

2. Sachin is planning to harvest rainwater.

3. Sachin will educate people to use water judicially in the following way.

1. Use mug for brushing, shaving and bathing.
2. Water plants with drip irrigation.
3. Use and reuse water in home activities.

1. Water table.
2. Seepage.
3. Water cycle.
4. Water management.
5. Aquifer.

Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decreases the open areas like parks, and playgrounds. This, in turn, decreases the seepage of rainwater into the ground. A cemented floor does not allow water to seep in easily, while in a grass lawn water seeps through in no time. Moreover a huge amount of water is required for construction work. Often groundwater is used for this purpose. So, on the one hand we are consuming more groundwater, and on the other we are allowing lesser water to seep into the ground. This results in depletion of water table. In fact, the water table in some parts of many cities has gone down to alarmingly low levels
Water is used by all the industries. Almost everything that we use needs water somewhere in its production process. The number of industries is increasing continuously. Water used by most of the industries is drawn from the ground.
A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems such as canals are there only in a few places. Even these systems may suffer from lack of water due to erratic rainfall. Therefore, farmers have to use groundwater for irrigation. Population pressure on agriculture forces increasing use of groundwater day by day. This results in depletion of water table.

Water is needed for various life activities. If we continue the misuse of water and do not conserve it, the groundwater level will be depleted. This may result into various consequences like:

1. Lowering of the water table Excessive pumping can lower the groundwater table.
2. Reduced surface water supply Groundwater and surface water are connected. When groundwater is over used, the lakes, streams and rivers connected to groundwater, can also have little supply.
3. Loss of plants from land We fully depend on the plants for food directly or indirectly. Plants need water to prepare their food. If there will be scarcity of water on earth, the plants will be unable to prepare their food. This inturn will lead to the end of the life because world without plants means no food, no oxygen, not enough rain and other innumerable problems.

Therefore, it is true that water is a precious resource.

Following industries and their products pollute the water.

1. Leather industries, e.g. shoes and other products.
2. Chemical factories, e.g. fertilisers, different insect repellant sprays, etc.
3. Petrochemical industries, e.g. petroleum and different fuels.
4. Oil industries.

All the above industries release pollutants such as asbestos, lead, mercury, nitrates, sulphur, etc in different rivers, lakes and ponds which are polluting the water and hence is responsible for depletion of water table.

Water management is the continuous matching of water resources with the water requirements of a place.

• Water management essentially involves activities that identify sources of water, prevent wastage of water, and implement recycling of water.
• It may also include treatment of water to make it suitable for human consumption.
• Prevent wastage of water.
• Water leaking from pipes.
• Leaking tap.
• Water over-flowing from buckets while clothes are being washed alongside.
• A person brushing teeth with the tap left running.

1. Avoid bath under a running shower, instead use a mug.
2. Get leaking pipelines repaired.
3. Avoid shaving and brushing teeth with running tap water.
4. Avoid overflowing of water in buckets.