Chapter 14: NATURAL RESOURCES

1.       The under-ground water and the water in rivers, lakes and ponds is also fresh.

2.       However, the availability of fresh water varies from place to place.

3.       Practically every summer, most places have to face a shortage of water.

4.       And in rural areas, where water supply systems have not been installed, people are forced to spend considerable amounts of time in fetching water from faraway sources.

Many municipal corporations are trying water-harvesting techniques to improve the availability of water, It is commonly called rain-roof water harvesting system or roof water recharging system, percolation ditches, open tree plantation etc. These techniques would increase the water by improved percolation and ground water recharge.

Why is water so necessary? And do all organisms require water?

1.       All cellular processes take place in a water medium.

2.       All the reactions that take place within our body and within the cells occur between substances that are dissolved in water.

3.       Substances are also transported from one part of the body to the other in a dissolved form.

4.       Hence, organisms need to maintain the level of water within their bodies in order to stay alive.

5.       Terrestrial life-forms require fresh water for this because their bodies cannot tolerate or get rid of the high amounts of dissolved salts in saline water.

6.       Thus, water sources need to be easily accessible for animals and plants to survive on land.

What is the relationship between water and the life?

            In nature is there any relationship between the amount of available water and the number and variety of plants and animals that can live in a given area?

1.       There is a greater variety and abundance of life in a region that receives 5 cm of rainfall in a year or a region that receives 200 cm of rainfall in a year

2.       The map showing rainfall patterns in the atlas shows that States like Kerala, Assam, Himachal Pradesh, in India would have the maximum biodiversity, as they receive highest annual rainfall.

3.       And the states like Gujrat, Rajsthan, parts of Maharashtra etc would have the least.

4.       The availability of water decides not only the number of individuals of each species that are able to survive in a particular area, but it also decides the diversity of life there.

5.       Of course, the availability of water is not the only factor that decides the sustainability of life in a region.

6.       Other factors like the temperature and nature of soil also matter.

7.       But water is one of the major resources which determine life on land.

WATER POLLUTION

What is water pollution? What are causes? What are ill-effects? What are control measures?

“The undesirable changes in the quality of natural water are called as water pollution”.

1.       Water dissolves the fertilizers and pesticides that we use on our farms.

2.       So some percentage of these substances are  washed into the water bodies.

3.       Sewage from our towns and cities and the waste from factories are also dumped into rivers or lakes.

4.       Specific industries also use water for cooling in various operations and later return this hot water to water-bodies.

5.       Some industries like chemical, leather, distilleries etc throw their effluents directly into water bodies.

6.       Another manner in which the temperature of the water in rivers can be affected is when water is released from dams.

7.       The water inside the deep reservoir would be colder than the water at the surface which gets heated by the Sun.

8.       All this can affect the life-forms that are found in these water bodies in various ways.

9.       It can encourage the growth of some life-forms and harm some other life-forms.

10.   This affects the balance between various organisms which had been established in that system.

11.   So we use the term water-pollution to cover the following effects:

A.     The addition of undesirable substances to water-bodies. These substances could be the fertilizers and pesticides used in farming or they could be poisonous substances, like mercury salts which are used by paper-industries. These could also be disease-causing organisms, like the bacteria which cause cholera.

B.      The removal of desirable substances from water-bodies. Dissolved oxygen is used by the animals and plants that live in water. Any change that reduces the amount of this dissolved oxygen would adversely affect these aquatic organisms. Other nutrients could also be depleted from the water bodies.

C.      A change in temperature. Aquatic organisms are used to a certain range of temperature in the water-body where they live, and a sudden marked change in this temperature would be dangerous for them or affect their breeding. The eggs and larvae of various animals are particularly susceptible to temperature changes.

Mineral Riches in the Soil

1.       What is the soil and how is it formed?

2.       How is soil formed?

3.       What is soil erosion?