Environmental Degradation Notes [For Dibrugarh University 2nd SEM NEP 2023]


For Dibrugarh University 2nd SEM NEP 2023

2.1 Land degradation: Causes and consequences.

2.2 Exploitation of surface and ground water,

2.3 Air pollution: anthropogenic causes, impact on health, agriculture, climate, hydrology


Land resources

Land resource is the most important natural resource which is essential for survival of life on earth. We depend on land for our basic amenities of life such as food, fibre, fuel, home etc. Land is a finite and most valuable resource as compared to other natural resource.

The top layer of the earth is called the soil. Soil can be classified as a renewable resource because it is continuously regenerated by natural process thought at a slow rate. But when the rete of erosion of soil is faster than the normal rate of renewable of soil, then the soil becomes a non-renewable resource.

Types of Land resources in India

The total geographical area of India is about 329 million hectares, but statistical information regarding land classification is available for only about 305 million hectares. Various types of land in India are given below:

a) Barren Land: 13% of the total reporting land area of our country is mountains, deserts, ravines and hills which cannot be used for cultivation. Barren land also includes those land which are left uncultivated for at least 5 years.

b) Forest land area: 22% of the total reporting land area of our country is covered by forests. Areas under forests includes all land classified as forests by law or administered as forests, whether state owned or private, and whether wooded or maintained as potential forest land.

c) Pastures and Grazing Land: 4% of the total land area of our country is classified as permanent pastures. Such lands are used for cattle grazing.

d) Culturable waste land: Culturable Waste Land comprises land available for cultivation, either taken up or just not taken up once for harvesting, but not harvested over the last five years more than in sequence, including that of the current year. In India percentage of the Culturable waste land is 4.41%.

e) Fallow Lands: These are cultivable & cultivated lands but remain uncultivated or fallow during a given year. Fallow land means land that is not cropped and kept cultivated throughout a growing season and has a vegetative cover of less than 25 percent. Fallow lands are classified into current fallows and other fallows lands. Current fallows represent cropped areas which are kept fallow during the current year, for example the seeding are may not be cropped in the same year. Other fallow lands are temporarily out of cultivation for a period not less than one year and not more than 5 years.

f) Agricultural lands: Out of the total land area of 329 million hectares, only 199 million i.e., 60% percent hectares are presently used for agricultural activities.

Land Degradation Meaning

Land degradation takes place when land use exceeds the carrying capacity of a system. It is a process in which the value of the biophysical environment is affected by a combination of human induced processes acting upon the land.

Houghton and Chairman defines land degradation “It encompass soil degradation and the deterioration of natural landscape and vegetation”. Human induced degradation includes the adverse effects of overgrazing, erosion, urbanization, disposal of industrial wastes, road construction, decline of plant communities and pollution of the air with its effects on land.

During the last few decades, there has been tremendous pressure on land in India due to increase in population. As urban centers grow and industrial expansion occurs, the agricultural land and forests shrink.

Causes of land degradation:

a) Soil erosion: Loss of top soil due to water and wind.

b) Water Logging: Accumulation of excess water under the ground.

c) Salinization: It is the accumulation of soluble salts of sodium, magnesium and calcium in soil to the extent that soil fertility is severely affected.

d) Contamination of soil with industrial waste like heavy metals, pesticides, fertilizers etc.

e) Overgrazing: Increase in livestock population results in overgrazing in pastures land.

f) Desertification: Desertification is a type of land degradation in which a relatively dry area of land becomes increasingly arid, typically losing its water bodies as well as vegetation and wildlife.

Also Read: Environmental Science Chapterwise Notes for 2nd SEM NEP 2023

– Unit 1: Environmental Science Notes

– Unit 2: Environmental Degradation Notes


Effects of land degradation

a) Deterioration of Soil texture.

b) Loss of soil fertility.

c) Accelerated soil erosion by wind and water.

d) Increased vulnerability of the environment or people to destruction or crisis.

e) Increase in water logging, salinity and acidity problems.

f) Affects social, economic and biodiversity level.

Soil Erosion – Meaning, Types, Causes and Conservation


Soil erosion is a naturally occurring process that affects all landforms. It is the removal of the top fertile layer of the soil. In other words, it is the displacement of the upper layer of soil due to water and wind. Soil erosion by water and wind is the most common and extensive form of soil erosion. The loss of soil from farmlands may be reflected in reduced crop production, lower surface water quality and damaged drainage networks. Intensive agriculture, deforestation and climate change are the most significant factors responsible for soil erosion. Due to soil erosion, one third of the world’s total cropland is eroded.

Types of Soil Erosion:

1. Normal erosion: This is caused by the gradual removal of top soil by natural processes which bring an equilibrium between physical, biological and hydrological activities and maintain a natural balance between erosion and renewal.

2. Accelerated erosion: This is mainly caused by man mad activities such as overgrazing, deforestation, mining etc.

Causes of soil erosion

1.    Loss of top soil: Loss of top soil due to wind and water.

2.    Deforestation: Deforestation for agriculture is the main cause of soil erosion. Due to high population in our country, deforestation is going at a rapid speed.

3.    Water Logging: Accumulation of excess water under the ground.

4.    Salinization: It is the accumulation of soluble salts of sodium, magnesium and calcium in soil to the extent that soil fertility is severely affected.

5.    Overgrazing: Overgrazing by cattle can cause soil erosion.

Checking/Conservation of Land resources

Land resources can be conserve by taking the following steps:

1. Soil erosion can be minimized by Afforestation in the hilly slopes.

2. Use of pesticides and fertilizers should be banned and organic fertilizers should be encouraged.

3. Proper disposal of industrial waste is a must.

4. Cultivation of tradition crops variety in a region should be encouraged.

5. Alley cropping helps in reducing soil erosion. In such cropping, crops are planted between rows of trees or shrubs.

6. Planting of trees in long rows along the cultivated land boundary so that strong winds can be blocked.

Desertification – Meaning, Causes and Effects

Desertification Meaning

Desertification is a type of land degradation in which a relatively dry area of land becomes increasingly arid, typically losing its water bodies as well as vegetation and wildlife. It is caused by climate change and soil erosion. When deserts appear automatically over the natural course of an Earth’s life cycle, then it can be called a natural phenomenon. Desertification is a significant global ecological and environmental problem. The UNO Conference on Desertification has defined it as “the destruction of the biological potential of land and can lead ultimately to desert like conditions.”

Causes of Desertification

a) Mismanagement of forests

b) Overgrazing by cattle

c) Mining and quarrying.

d) Deforestation.

e) Climate Change

f) Excessive use of fertilizers and pesticides.

g) Stripping the land of resources.

Effects of Desertification

a) Farming becomes next to impossible in such lands.

b) Decrease in crop yields which can lead to high inflation and hunger problem.

c) If an area becomes a desert, the water quality is going to become worst.

d) Reduction in crops and poor water quality leads to poverty like situation.

e) Migration of people from such areas for better life leads to over population and unemployment in other areas.

Water Resources

Water resources are a critical component of life and the environment. However, there are several issues related to water resources that have emerged due to human activities. In this context, the following are the notes on water resources, their use, overexploitation, and related conflicts.

Use and Over-exploitation of Surface and Groundwater

A. Surface water:

Surface water resources are the water sources that are available on the Earth’s surface, such as rivers, lakes, and ponds. These resources are essential for human survival and ecosystem functioning. However, their use for agriculture, industrial, and domestic purposes, as well as pollution, has led to the depletion of these resources.

Sources of surface water include precipitation, surface runoff, and melting snow and ice. Surface water is commonly used for irrigation in agriculture, cooling in power plants, and domestic and industrial purposes. However, the pollution of surface water due to human activities, such as dumping of waste and discharge of industrial effluents, has led to a decline in water quality.

B. Groundwater:

Groundwater is the water that is stored beneath the Earth’s surface in aquifers. These resources are essential for human survival and ecosystem functioning. However, over-exploitation of groundwater due to its use for irrigation and drinking water has led to depletion and contamination.

Sources of groundwater include precipitation, infiltration of surface water, and recharge from rivers and lakes. Groundwater is commonly used for irrigation in agriculture, drinking water, and industrial purposes. However, over-exploitation of groundwater has led to depletion and contamination due to the infiltration of pollutants from the surface.


Floods are natural disasters that occur when a region is inundated by water due to heavy rainfall, snowmelt, or the failure of dams and levees. Floods can have severe impacts on the environment and society.

Causes of floods:

a) Heavy rainfall due to cyclones, monsoons, or thunderstorms

b) Rapid melting of snow or ice

c) Dam or levee failures

d) Changes in land use, such as deforestation or urbanization

e) Climate change leading to extreme weather events

Effects of floods on the environment and society:

a) Loss of life and property damage

b) Displacement of people and disruption of livelihoods

c) Contamination of water and soil

d) Spread of waterborne diseases

e) Erosion of soil and loss of fertile land

Measures to mitigate the effects of floods:

a) Construction of dams and levees to control water flow

b) Implementation of flood warning and evacuation systems

c) Restoration and protection of wetlands and floodplains

d) Implementation of zoning regulations and land-use planning to prevent development in flood-prone areas

e) Building homes and infrastructure to withstand flooding.


Droughts are natural disasters that occur when a region experiences a prolonged period of low rainfall, leading to water scarcity. Droughts can have severe impacts on the environment and society.

Causes of droughts:

a) Lack of rainfall or precipitation

b) Climate change and variability

c) Overuse of water resources

d) Deforestation and land-use changes

e) Natural disasters such as wildfires or heatwaves

Effects of droughts on the environment and society:

a) Crop failure and food shortages

b) Water scarcity and depletion of groundwater resources

c) Economic losses for farmers and related industries

d) Increased risk of wildfires and dust storms

e) Public health impacts, such as malnutrition and waterborne diseases

Measures to mitigate the effects of droughts:

a) Conservation and efficient use of water resources

b) Rainwater harvesting and groundwater recharge

c) Drought-resistant crop varieties and farming techniques

d) Water-use regulations and pricing mechanisms

e) Early warning systems and drought preparedness planning

Water Conflicts – International and Inter-state

Water conflicts are a common occurrence due to the unequal distribution of water resources, population growth, and increasing demand for water for agriculture, industrial, and domestic purposes. There are two types of water conflicts: international and inter-state.

A. International conflicts:

Indo-China water disputes: The dispute is related to the Brahmaputra River, which flows through China, India, and Bangladesh. China is building a series of hydroelectric dams on the river, which has raised concerns in India and Bangladesh about the potential impact on downstream water flow and water quality.

Indo-Bangladesh water disputes: The dispute is related to the sharing of the Ganges River water between India and Bangladesh. The Farakka Barrage, built by India on the Ganges River, has been a source of tension between the two countries due to the reduction in the flow of water downstream.

B. Inter-state conflicts:

Cauvery river water disputes between Karnataka and Tamil Nadu: The conflict is related to the sharing of water from the Cauvery River between the two states. Karnataka and Tamil Nadu have been in a dispute over water sharing for over a century, with both states claiming a larger share of the river water.

Mahanadi river water disputes between Odisha and Chhattisgarh: The conflict is related to the sharing of water from the Mahanadi River between the two states. Odisha and Chhattisgarh have been in a dispute over water sharing for several years, with Odisha claiming that Chhattisgarh is building dams and barrages upstream that would reduce the flow of water downstream.

Causes of water conflicts:

a) Competition for limited water resources due to population growth, increasing urbanization, and industrialization.

b) Unequal distribution of water resources.

c) Climate change and variability.

Resolution of water conflicts:

a) Legal and institutional mechanisms such as treaties, agreements, and laws.

b) Negotiations and dialogue between the conflicting parties.

c) Use of scientific and technical solutions such as water conservation, rainwater harvesting, and water recycling.

Air Pollution

We all breathe in air, we can feel, and even smell the air and say whether it is fresh or stale. The pollution in air may not be noticed until we see smoke coming out from some source. All human activities from cooking at home to activities in highly mechanized industries contribute to air pollution.

The World Health Organization defines air pollution as “the presence of materials in the air in such concentration which are harmful to man and his environment.”

In Simple words, it is the occurrence or addition of foreign particles, gases and other pollutants into the air which have an adverse effect on human beings, animals, vegetation, buildings, etc.

Air Pollutants

Pollutants are classified into primary and secondary pollutants.

Primary pollutants: they are emitted into the atmosphere directly from the source and retains the same chemical form. Examples are carbon monoxide, sulphur oxides, nitrogen oxides, hydrocarbons, suspended particulate matter(SPM).

Secondary pollutants: they are formed by the inter mingling and reactions of primary pollutants. Examples are photochemical smog, acid rain, PAN etc.

Sources and causes of Air Pollution

The sources of air pollution are classified into two groups: Natural and Man- made sources.

(a) Natural sources:

1)    Volcanic eruption: releasing poisonous gases like SO2, H2S, CO etc.

2)    Forest fires: Very large quantities of smoke and particulate matter are liberated during their breakout.

3)   Decomposition of organic and inorganic substances: Methane gas, carbon dioxide is released into the air.

4)    Dust: Dust is always present in the atmosphere in varying amount.

(b) Manmade sources:

1)    Deforestation.

2)   Burning of fossil fuels.

3)   Emission from vehicles.

4)   Rapid industrialization.

5)   Modern agricultural practices.

Effects of Air Pollution

Air pollution is very dangerous for health. Some of the adverse effects of air pollution are given below:

1. Air pollution affects our respiratory system and causes breathing difficulties.

2. Diseases such as bronchitis, asthma, lung cancer, tuberculosis and pneumonia caused due to air pollution.

3. Increased concentration of carbon dioxide in atmosphere causes global warming.

4. Air pollution causes acid rain which damages crop plants, trees and buildings. It also makes the soil acidic.

5. Ozone layer depletion due to air pollution which allows ultraviolet radiation to reach the earth. Such radiation causes various skin and eye diseases.

6. Excess nitrogen oxides in the atmosphere results in respiratory problems and bronchitis.

Measures to Control Air Pollution

Air pollution can control from the following points:

1. A raw material for feedstock should be renewable rather than depleting.

2. Better designed equipment and smokeless fuels should be used in houses and industries. Less polluting fuels should be used.

3. Growing plants capable of fixing carbon monoxide. Example: Phaseolus vulgaris, Daucus carota.

4. Growing plants capable of metabolizing nitrogen oxides and other gaseous pollutants. Example: Vitis, Pimis, Pyrus etc.

5. Use of non-conventional sources of energy should be encouraged.

6. Use of public transport to control fuel consumption.

7. Automobiles should be properly maintained and adhere to emission control standards.

8. Proper Environmental Impact Assessment for any developmental work must be done.

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