8.Chapter 2.Learning.
Natural Resources.
Natural Resources: Land, Soil and Water Earth is a unique
planet in the solar system. Life is
possible on the earth because of the four spheres --- lithosphere, atmosphere,
hydrosphere and biosphere, Earth's surface is divided into two parts, i.e. land and water. Land covers about 30% of the total surface
area of the earth and water about 70% of its total surface planet Earth LAND
RESOURCES The most important natural resource upon which all human activity is
based is land. It is used for growing
crops, building houses, constructing roads and railway tracks, further
industries, grazing animals, mining, etc.
In short, almost all human activities related to food, shelter and
clothing take place on land. Lithosphere
consists of loose surface material called soil.
It is a combination of organic and inorganic matter. The organic component which consists of dead
and decomposed parts of animals and plants is known as humus. The inorganic component is formed by rock
particles and minerals, such as lime, iron, etc. Soil is formed as a result of the long,
continued weathering process of rocks.
It also contains water and air, which occupy its pore spaces. About 90% of the world's population is
inhabited in the plain areas of the alluvial soils of the tropical and sub -
tropical areas. These are the areas of
intensive crop cultivation with high yields.
All these areas support dense population. In contrast, sparse population is seen in
areas of high altitudes, deserts and equatorial forest areas where slopes are
steep, temperature is either too hot or too cold, soils are thin and
infertile. These areas are inhabited by
people who are engaged in hunting, gathering, fishing and shifting
agriculture. Land Use Land is used for
various purposes, such as cultivation of crops, building of houses,
construction of roads and railways, grazing of animals, etc. This is commonly known as land use
pattern. The percentage of land used for
various purposes varies from one region to another. The utilization of land is determined by the
continuous interplay of the physical factors, such as relief, soil, climatic
conditions, mineral resources, etc. ,
and the human factors like density of population and the technological and
social requirements of the people.
The study of land use pattern is important for the economic
planning of a nation. It helps in
assessing shortcomings in the land utilization countries decide the land use
according to their development goals and availability of natural resources,
according to the scientific criteria, 33% area of the world should be under
forest to maintain ecological balance.
At present, only 31.6% area of the world is covered by forest. Out of this, 93% of the forests are naturally
occurring, while the other 7% are man - made.
The earth's forest cover is unevenly distributed with some countries
having most of their land covered by forest while others have only limited
forest cover. It is very important for
us to take initiative to conserve forests by discouraging deforestation and
encouraging afforestation. Do you
know? Surinam has the maximum forest
cover in the world. India has the
maximum arable land in the world followed by the United States and China. The availability of land on earth is
limited. There is conflict over the
access and rights of this natural resource.
It has also resulted in tough competition between the agriculture and
other sectors over usage of land.
Moreover, land also suffers from various problems, such as soil erosion,
degradation and deforestation. It is
important to reduce land degradation and ensure the optimum use of land
resources for the benefit of the present and future generations, land
management is a holistic approach for achieving productive and balanced
ecosystem by integrating socio - economic needs of the people. SOIL RESOURCES A large part of the earth's
land surface is covered with soil. As a
resource, soil is of immense value to the farmers, agricultural production is
mainly dependent upon the fertility of soil.
Rich and deep soil cover, with a high degree of fertility, favored
agricultural production. On the other hand,
if the soil cover is shallow and lacks fertility, agricultural production will
be less. Therefore, a thick layer of
fertile soil is very important for the growth of plants. Though indirectly, animals also depend upon
the soil to satisfy their basic needs, as soil gives nutrients to plants. It gives shelter to insects and animals like
rats, snakes, ants, earthworms, etc.
Soil s also used for making bricks and pottery factors affecting soil
formation egetation cover and time. Let
us study each one of them. Soil
formation is influenced by five factors - the parent rock, the topography, the
climate, the 10
The Parent Rock: The original rock from which soil is formed
by the process of weathering is known as the parent rock. For example, the black soil of India is
derived from the lava rock, The Topography: Topographical variations, such as
mountains, plateaus and plains affect the thickness of a soil cover. In mountainous regions, on the steep slopes,
the top layer of soil is shallow and thin.
On the other hand, at gentle slopes, the soil cover is thick and
deep. Soil cover is always thick in
plains. For example, the northern plains
of India have thick soil cover as compared to the Himalayas. Even within mountains, river valleys have
thick soil cover. The Climate: Climatic
factors, like temperature and rainfall, affect the soil formation. In the areas of high rainfall and extreme
temperature, rocks are easily weathered.
In Rajasthan, due to extreme difference in day and night temperatures,
rocks expand and contract, which results in quick formation of the soil. In regions of heavy rainfall, soluble rock
material easily gets dissolved and washed away by the running water. Thus, it affects the soil formation The
Vegetation Cover: At times, plants grow in the cracks existing in a rock. With time, roots of these plants start penetrating
in the cracks and make them wider. As a
result, cracks disintegrate into smaller pieces and help in the soil
formation. Remains of dead or decomposed
plants and animals provide humus to the soil, which enriches the fertility of
the soil. The soil of densely forested
area is generally very rich in humus content.
• Time: Time gives maturity to the soil.
Although, soil is a renewable resource, yet it takes thousands of years
to develop a very thin layer of soil on the earth's surface. For example, the Nile delta and delta formed
by the Ganga and Brahmaputra rivers have very deep and fertile soil. Fertile soil is essential for
agriculture. It helps in enjoying food security
of the world. But it has been observed
that the fertility of soil is severely damaged by soil erosion. In soil erosion, the top layer of the soil is
removed by natural agents, such as water, wind, glacier, etc. , and by mankind's unwise actions, such as
deforestation, Soil erosion over - grazing and mining. The need to conserve soil from erosion has
become one of the major environmental concerns.
11
Soil Conservation Soil conversation means prevention of soil
from being eroded. Various methods for
soil conservation are: • Afforestation is the process of planting more 4 trees
and seeds on the land. It reduces the
surface runoff and binds the soil. M
Rows of trees or shelter belts are planted in desert regions to protect the
fields from wind erosion. • Overgrazing
by animals like sheep and goats must be checked. Fodder crops should be raised. The free movement of animals in the fields
Afforestation should be restricted.
Steps should be taken to check reckless cutting or felling of trees. Floods should be avoided by building dams
across the rivers. Terrace farming and
contour plowing should be encouraged across the hill slopes. Scientific agriculture practices like
rotation of crops, strip cropping, etc.
, should be systematically followed.
Dam across the river Contour ploughing Do You Know? Terrace farming means growing, of crops on
level steps or terraces constructed on hill sides. Contour ploughing is a technique of plowing
parallel to the contours of a hill slope rather than up and down the slope, so
as to reduce soil erosion.
WATER RESOURCES Water is one of the most precious
resource. Earth is also called a watery
planet because nearly 70% of the earth's surface is covered with water. About 97% of the earth's total water is
present in the oceans and seas. This is
saline water which supports incredible biodiversity of marine life, but is not
suitable for human consumption or for watering crops. The remaining 3% is fresh water, which is
found in the following forms: • 0.32% is available in lakes, rivers, Do You
Know? atmospheric and soil moisture,
etc. • 2.0% is in the form of ice caps
and surface water means water which is present glaciers. above the earth's surface in the form of
rivers, streams, lakes, etc. 0.68% is
available as ground water. The main
source of fresh water is rainfall. The
rain water continuously gets recycled in nature through evaporation,
condensation and precipitation, which is known as hydrological cycle. Most of the fresh water on the earth is found
in the rivers, streams, lakes, ponds, ice caps and underground water. The distribution of fresh water resources on
the earth's surface is uneven.
Condensation forming Cloud Water Morage Transport Condensation inice and
snow fighting dhe EvapotFresh water is found in abundance at places which receive
heavy rainfall, whereas availability of water is less in the areas where
rainfall is low. The average Do You
Know? annual precipitation of the world
is estimated to be 1,050 millimeters per year or 2.9 millimeters per day
millimetre is a unit of length equal to 1/1000 metre The given on the adjacent
page indicates the uneven distribution of rainfall in the world. Areas of High Rainfall: Equatorial regions in
South America, Africa and South - East Asia.
Areas of Low Rainfall: Tropical Deserts - Sahara, Arabian, Central and
Western Australia, Kalahari, Central and Northern Eurasia, Central Asia, Polar
areas, etc. Pollution of Water The
quality of water in some rivers is adversely affected as the untreated
industrial waste and urban waste is dumped into them. This makes the river water unsuitable for
consumption. The polluted water, if
consumed, causes many diseases like cholera, jaundice, typhoid, etc. It also disturbs the ecosystem. Hence, serious efforts are being made to
clean water in the rivers. Multipurpose
River Valley Projects have been developed all over the world to use water. (These pollution of water projects serve many
objectives at the same time. Under a multipurpose river valley project, a dam
or series of dams are constructed across the river for storing water. This stored
water used for several purposes, such as irriga generating
hydroelectricity, afforestation, flood
control, navigation, etc.) Damodar River Valley Project and Hirakud Dam in
India, Aswan in Egypt and Hoover Valley Project in USA are some of the major
multipurpose river valley projects.
Hirakud dam, India Hoover dam, USA 15ranspiration Evaporation Surface
runoll WE Hydrological cycle 13
Fresh water is found in abundance at places which receive
heavy rainfall, whereas availability of water is less in the areas where
rainfall is low. The average Do You
Know? annual precipitation of the world
is estimated to be 1,050 millimeters per year or 2.9 millimeters per day
millimetre is a unit of length equal to 1/1000 metre The given on the adjacent
page indicates the uneven distribution of rainfall in the world. Areas of High Rainfall: Equatorial regions in
South America, Africa and South - East Asia.
Areas of Low Rainfall: Tropical Deserts - Sahara, Arabian, Central and
Western Australia, Kalahari, Central and Northern Eurasia, Central Asia, Polar
areas, etc. Pollution of Water The
quality of water in some rivers is adversely affected as the untreated
industrial waste and urban waste is dumped into them. This makes the river water unsuitable for
consumption. The polluted water, if
consumed, causes many diseases like cholera, jaundice, typhoid, etc. It also disturbs the ecosystem. Hence, serious efforts are being made to
clean water in the rivers. Multipurpose
River Valley Projects have been developed all over the world to use water. (These pollution of water projects serve many
objectives at the same time. Under a multipurpose river valley project, a dam
or series of dams are constructed across the river for storing water. This
stored water used for several purposes, such as irriga generating
hydroelectricity, afforestation, flood
control, navigation, etc.) Damodar River Valley Project and Hirakud Dam in
India, Aswan in Egypt and Hoover Valley Project in USA are some of the major
multipurpose river valley projects.
Hirakud dam, India Hoover dam, USA 15
The dams are very useful for various purposes. But large dams have come under a lot of
criticism from environmentalists, as they are causing ecological problems, like
• Extensive forests submerged under water.
Aquatic life gets affected. River
water gets diverted, Result in soil erosion.
• Population gets displaced.
During excessive rain, floods are caused. Water Conservation Methods Water is an
indispensable resource. The sources of
water are limited and are reducing every year.
Due to the effects of global warming, the frequency of rain has also
become unpredictable therefore, it is very essential for us to conserve
it. Following are some of the ways by
which water can be conserved. Water
harvesting is one of the methods of saving surface water runoff. The surface water runoff can be minimized by
having vegetation cover to improve underground storage. The demand of water for industries can be met
by the recycled water. The domestic
demand can also be reduced by using modern methods of recycling. The already used water can Water recycling
plant be reused for watering plants, flushing toilets, etc. Water can be saved by adopting modern methods
of irrigation, such as drip or trickle irrigation technique and sprinkler
method of irrigation. Trickle method
Sprinkler method 16
The rain water can be impounded by making dams across the
rivers. • Water can be conserved by
installing water fixtures, such as sensor taps in public places. • Maintenance of lakes and ponds also helps
in increasing the aquifer (water table) of underground water. Water can be conserved by educating and
sensitizing people towards the urgent need to conserve water and not to waste
fresh water. Water conservation
Keywords. altitude: height above the
mean sea level. ecosystem:
interdependency or inter - relationship of biological elements of the
environment on their physical environment.
deforestation: cutting down of large number of trees in an area or
clearing of the forest cover. • drip
irrigation: it is a form of irrigation in which water drips in small quantity
on roots of the plants. glacier: moving
mass of ice like a river. precipitation:
process in which water vapors fall on the ground in the form of rain, snow, hail
and sleet. sprinkler method: an
irrigation technique of spraying water on the plants like rain. topography: physical features, relief or
landforms like mountains, plateaus, plains, etc. Water harvesting: storing the rainwater
through various methods. water table:
the level below which the ground is completely saturated with water. weathering process of disintegration of rocks
into smaller pieces till it gets converted into soil. .
. 17
The rain water can be impounded by making dams across the rivers. • Water can be conserved by installing water fixtures, such as sensor taps in public places • Maintenance of lakes and ponds also helps in increasing the aquifer (water table) of underground water. Water can be conserved by educating and sensitizing people towards the urgent need to conserve water and not to waste fresh water. Water conservation
Keywords altitude; height above the mean sea level. ecosystem: interdependency or inter - relationship of biological elements of the environment on their physical environment. deforestation: cutting down of large number of trees in an area or clearing of the forest cover. drip irrigation: it is a form of irrigation in which water drips in small quantity on roots of the plants. glacier: moving mass of ice like a river. precipitation process in which water vapors fall on the ground in the form of rain, snow, hail and sleet. sprinkler method: an irrigation technique of spraying water on the plants like rain. topography: physical features, relief or landforms like mountains, plateaus, plains, etc. Water harvesting: storing the rainwater through various methods. water table: the level below which the ground is completely saturated with water. weathering: process of disintegration of rocks into smaller pieces till it gets converted into soil. 17
The rain water can be impounded by making dams across the rivers. • Water can be conserved by installing water fixtures, such as sensor taps in public places • Maintenance of lakes and ponds also helps in increasing the aquifer (water table) of underground water. Water can be conserved by educating and sensitizing people towards the urgent need to conserve water and not to waste fresh water. Water conservation
Keywords altitude; height above the mean sea level. ecosystem: interdependency or inter - relationship of biological elements of the environment on their physical environment. deforestation: cutting down of large number of trees in an area or clearing of the forest cover. drip irrigation: it is a form of irrigation in which water drips in small quantity on roots of the plants. glacier: moving mass of ice like a river. precipitation process in which water vapors fall on the ground in the form of rain, snow, hail and sleet. sprinkler method: an irrigation technique of spraying water on the plants like rain. topography: physical features, relief or landforms like mountains, plateaus, plains, etc. Water harvesting: storing the rainwater through various methods. water table: the level below which the ground is completely saturated with water. weathering: process of disintegration of rocks into smaller pieces till it gets converted into soil. 17
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