Chapter- 1

INDIA – SIZE AND LOCATION

LOCATION-

• Extends between latitudes 8°4'N and 37°6'N and longitudes 68°7'E and 97°25'E
• The Tropic of Cancer (23° 30'N) divides the country into almost two equal parts.
• The southernmost point of the Indian Union– ‘Indira Point’ got submerged under the sea water in 2004 during the Tsunami.
• Land mass of India- 3.28 million square km
• 2.4% of the total geographical area of the world
• 7th largest country of the world
• Land boundary- 15,200 km
• Total length of the coastline (A & N and Lakshadweep)- 7,516.6 km
• From Gujarat to Arunachal Pradesh, there is a time lag of two hours. Hence, time along the Standard Meridian of India (82°30'E) passing through Mirzapur (in UP) is taken as the standard time for the whole country.
• Latitudinal extent influences the duration of day and night, as one move from south to north.
• Deccan Peninsula protrudes into the Indian Ocean, thus helping India to establish close contact with West Asia, Africa and Europe from the western coast and with Southeast and East Asia from the eastern coast.
• Sri Lanka is separated from India by a narrow channel of sea formed by the Palk Strait and the Gulf of Mannar

The Northern Plain

The Peninsular Plateau

• Tableland composed of the old crystalline, igneous and metamorphic rocks.
• Formed due to the breaking and drifting of the Gondwana land and thus, making it a part of the oldest landmass.
• The plateau has broad and shallow valleys and rounded hills.
• This plateau consists of two broad divisions, namely, the Central Highlands and the Deccan Plateau.
• The part of the peninsular plateau lying to the north of the Narmada River, covering a major area of the Malwa plateau, is known as the Central Highlands.
• The Vindhyan range is bounded by the Satpura range on the south and the Aravalli’s on the northwest.
• The further westward extension gradually merges with the sandy and rocky desert of Rajasthan.
• The flow of the rivers draining this region, namely the Chambal, the Sind, the Betwa and the Ken is from southwest to northeast, thus indicating the slope.
• The Central Highlands are wider in the west but narrower in the east. The eastward extensions of this plateau are locally known as the Bundelkhand and Baghelkhand.
• The Chotanagpur plateau marks the further eastward extension, drained by the Damodar River.
• The Deccan Plateau is a triangular landmass that lies to the south of the river Narmada.
• The Satpura range flanks its broad base in the north, while the Mahadev, the Kaimur hills and the Maikal range from its eastern extensions.
• The Deccan Plateau is higher in the west and slopes gently eastwards.
• An extension of the Plateau is also visible in the northeast, locally known as the Meghalaya, Karbi-Anglong Plateau and North Cachar Hills.
• It is separated by a fault from the Chotanagpur Plateau.
• Three prominent hill ranges from the west to the east are the Garo, the Khasi and the Jaintia Hills.

Western and Eastern Ghats

• The Western Ghats and the Eastern Ghats mark the western and the eastern edges of the Deccan Plateau respectively.
• Western Ghats lie parallel to the western coast.
• They are continuous and can be crossed through passes only.
• The Western Ghats are higher than the Eastern Ghats.
• Their average elevation is 900– 1600 meters as against 600 meters of the Eastern Ghats.
• The Eastern Ghats stretch from the Mahanadi Valley to the Nilgiris in the south.
• The Eastern Ghats are discontinuous and irregular and dissected by rivers draining into the Bay of Bengal.
• The Western Ghats cause orographic rain by facing the rain bearing moist winds to rise along the western slopes of the Ghats.
• The Western Ghats are known by different local names.
• The height of the Western Ghats progressively increases from north to south.
• The highest peaks include the Anai Mudi (2,695 meters) and the Doda Betta (2,637 meters).
• Mahendragiri (1,501 meters) is the highest peak in the Eastern Ghats.
• Shevroy Hills and the Javadi Hills are located to the southeast of the Eastern Ghats.
• One of the distinct features of the peninsular plateau is the black soil area known as Deccan Trap.
• This is of volcanic origin; hence, the rocks are igneous.
• Actually, these rocks have denuded over time and are responsible for the formation of black soil.
• The Aravalli Hills lie on the western and north- western margins of the Peninsular plateau.
• These are highly eroded hills and are found as broken hills.
• They extend from Gujarat to Delhi in a southwest-northeast direction.

The Indian Desert

• The Indian desert lies towards the western margins of the Aravalli Hills.
• It is an undulating sandy plain covered with sand dunes.
• This region receives very low rainfall below 150 mm per year.
• It has arid climate with low vegetation cover.
• Streams appear during the rainy season.
• Soon after they disappear into the sand as they do not have enough water to reach the sea.
• Luni is the only large river in this region.
• Barchans (crescent-shaped dunes) cover larger areas but longitudinal dunes become more prominent near the Indo-Pakistan boundary.
• If you visit Jaisalmer, you may go to see a group of barchans

The Coastal Plains

• The Peninsular plateau is flanked by stretch of narrow coastal strips, running along the Arabian Sea on the west and the Bay of Bengal on the east.
• The western coast, sandwiched between the Western Ghats and the Arabian Sea, is a narrow plain.
• It consists of three sections.
• The northern part of the coast is called the Konkan (Mumbai – Goa), the central stretch is called the Kannad Plain, while the southern stretch is referred to as the Malabar coast
• The plains along the Bay of Bengal are wide and level.
• In the northern part, it is referred to as the Northern Circar, while the southern part is known as the Coromandel Coast.
• Large rivers, such as the Mahanadi, the Godavari, the Krishna and the Kaveri have formed extensive delta on this coast.
• Lake Chilika is an important feature along the eastern coast
• The Chilika Lake is the largest salt water lake in India.
• It lies in the state of Odisha, to the south of the Mahanadi delta.

The Islands-

Lakshadweep Islands

• Group lying close to the Malabar Coast of Kerala.
• This group of islands is composed of small coral islands. Earlier they were known as Laccadive, Minicoy and Amendivi.
• In 1973, these were named as Lakshadweep.
• It covers small area of 32 sq km.
• Kavaratti Island is the administrative headquarters of Lakshadweep.
• This island group has great diversity of flora and fauna.
• The Pitti Island, which is uninhabited, has a bird sanctuary.

Andaman and Nicobar islands-

• Chain of islands located in the Bay of Bengal extending from north to south.
• They are bigger in size and are more numerous and scattered.
• The entire group of islands is divided into two broad categories – The Andaman in the north and the Nicobar in the south.
• It is believed that these islands are an elevated portion of submarine mountains.
• These island groups are of great strategic importance for the country. There is great diversity of flora and fauna in this group of islands too.
• These islands lie close to equator and experience equatorial climate and have thick forest cover.
• India’s only active volcano is found on Barren Island in Andaman and Nicobar group of Islands.

Chapter- 2

PHYSICAL FEATURES OF INDIA

Theory of Plate Tectonics-

• Crust (upper part) of the earth has been formed out of 7 major and some minor plates.
• Movement of the plates 

Building up of stresses within the plates and the continental rocks above, leading to folding, faulting and volcanic activity

Broadly, these plate movements are classified into three types

• The oldest landmass, (the Peninsula part), was a part of the Gondwana land.
• Gondwana land- India, Australia, South Africa, South America and Antarctica as one single land mass.
• The convectional currents split the crust into a number of pieces, thus leading to the drifting of the Indo- Australian plate after being separated from the Gondwana land, towards north.
• Northward drift resulted in the collision of the plate with the much larger Eurasian Plate.
• Due to this collision, the sedimentary rocks which were accumulated in the geosyncline known as the Tethys were folded to form the mountain system of western Asia and Himalaya.
• The Himalayan uplift out of the Tethys sea and subsidence of the northern flank of the peninsular plateau resulted in the formation of a large basin.
• In due course of time this depression, gradually got filled with deposition of sediments by the rivers flowing from the mountains in the north and the peninsular plateau in the south.
• A flat land of extensive alluvial deposits led to the formation of the northern plains of India.
• The northern plains are formed of alluvial deposits.
• The peninsular plateau is composed of igneous and metamorphic rocks with gently rising hills and wide valleys.

MAJOR PHYSIOGRAPHIC DIVISIONS

1. The Himalayan Mountains
2. The Northern Plains
3. The Peninsular Plateau
4. The Indian Desert
5. The Coastal

• Himalayas lying between Indus and Satluj has been traditionally known as Punjab Himalaya but it is also known regionally as Kashmir and Himachal Himalaya from west to east respectively
• The part of the Himalayas lying between Satluj and Kali rivers is known as Kumaon Himalayas.
• The Kali and Teesta rivers demarcate the Nepal Himalayas and the part lying between Teesta and Dihang rivers is known as Assam Himalayas.
• The Brahmaputra marks the eastern-most boundary of the Himalayas
• Beyond the Dihang gorge, the Himalayas bend sharply to the south and spread along the eastern boundary of India.  They are known as the Purvanchal or the Eastern hills and mountains.
• These hills running through the north-eastern states are mostly composed of strong sandstones, which are sedimentary rocks.

Purvanchal- Patkai hills, the Naga Hills, the Manipur hills and the Mizo hills

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Chapter- 3

Drainage

Accordingly, the Indian rivers are divided into two major groups:

1. The Himalayan rivers; and
2. The Peninsular rivers

Drainage Patterns

The Himalayan Rivers

Indus, the Ganga and the Brahmaputra. These rivers are long, and are joined by many large and important tributaries. A river along with its tributaries may be called a river system.

The Indus River System

• The river Indus rises in Tibet, near Lake Mansarovar.
• Flowing west, it enters India in the Ladakh district of Jammu and Kashmir.
• It forms a picturesque gorge in this part.
• Several tributaries, the Zaskar, the Nubra, the Shyok and the Hunza, join it in the Kashmir region.
• The Indus flows through Baltistan and Gilgit and emerges from the mountains at Attock.
• The Satluj, the Beas, the Ravi, the Chenab and the Jhelum join together to enter the Indus near Mithankot in Pakistan.
• Beyond this, the Indus flows southwards eventually reaching the Arabian Sea, east of Karachi.
• A little over a third of the Indus basin is located in India in the states of Jammu and Kashmir, Himachal Pradesh and Punjab and the rest is in Pakistan.
• According to the regulations of the Indus Water Treaty (1960), India can use only 20 per cent of the total water carried by the Indus river system.
• This water is used for irrigation in Punjab, Haryana and the southern and the western parts of Rajasthan.
• The main tributaries, which come from the peninsular uplands, are the Chambal, the Betwa and the Son. These rise from semi-arid areas, have shorter courses and do not carry much water in them.
• The Namami Gange Programme is an Integrated Conservation Mission approved as a ‘flagship programme’ by the Union Government in June 2014 to accomplish the twin objectives of effective abatement of pollution, conservation and rejuvenation of the national river, Ganga.
• Namami Ganga- Enlarged with the waters from its right and left bank tributaries, the Ganga flows eastwards till Farakka in West Bengal. This is the northernmost point of the Ganga delta.
• The river bifurcates here; the Bhagirathi-Hooghly (a distributary) flows southwards through the deltaic plains to the Bay of Bengal.
• The mainstream flows southwards into Bangladesh and is joined by the Brahmaputra.
• Further downstream, it is known as the Meghna.
• This mighty river, with waters from the Ganga and the Brahmaputra, flows into the Bay of Bengal.
• The delta formed by these rivers is known as the Sunderban Delta.

The Ganga River System

• The headwaters of the Ganga, called the ‘Bhagirathi’ is fed by the Gangotri Glacier and joined by the Alaknanda at Devaprayag in Uttarakhand.
• At Haridwar, the Ganga emerges from the mountains on to the plains
• The Ganga is joined by many tributaries from the Himalayas, a few of them being major rivers, such as the Yamuna, the Ghaghara, the Gandak and the Kosi.
• The river Yamuna rises from the Yamunotri Glacier in the Himalayas.
• It flows parallel to the Ganga and as a right bank tributary meets the Ganga at Allahabad.
• The Ghaghara, the Gandak and the Kosi rise in the Nepal Himalaya.
• They are the rivers, which flood parts of the northern plains every year, causing widespread damage to life and property, whereas, they enrich the soil for agricultural use.
• The Sunderban Delta derived its name from the Sundari tree, which grows well in marshland.
• It is the world’s largest and fastest growing delta.
• It is also the home of Royal Bengal tiger.
• Ambala is located on the water divide between the Indus and the Ganga river systems
• River develops large meanders.

The Brahmaputra River System

• The Brahmaputra rises in Tibet east of Mansarovar Lake very close to the sources of the Indus and the Satluj.
• It is slightly longer than the Indus, and most of its course lies outside India.
• It flows eastwards parallel to the Himalayas.
• On reaching the Namcha Barwa (7757 m), it takes a ‘U’ turn and enters India in Arunachal Pradesh through a gorge.
• Here, it is called the Dihang and it is joined by the Dibang, the Lohit, and many other tributaries to form the Brahmaputra in Assam.
• Brahmaputra is known as the Tsang Po in Tibet and Jamuna in Bangladesh.
• In Tibet, the river carries a smaller volume of water and less silt as it is a cold and a dry area.
• In India, it passes through a region of high rainfall.
• Here the river carries a large volume of water and considerable amount of silt.
• The Brahmaputra has a braided channel in its entire length in Assam and forms many riverine islands.
• Every year during the rainy season, the river overflows its banks, causing widespread devastation due to floods in Assam and Bangladesh.
• Unlike other north Indian rivers, the Brahmaputra is marked by huge deposits of silt on its bed causing the riverbed to rise.
• The river also shifts its channel frequently.

The Peninsular Rivers

• The main water divide in Peninsular India is formed by the Western Ghats, which runs from north to south close to the western coast.
• Most of the major rivers of the Peninsula, such as the Mahanadi, the Godavari, the Krishna and the Kaveri flow eastwards and drain into the Bay of Bengal.
• These rivers make deltas at their mouths.
• There are numerous small streams flowing west of the Western Ghats.
• The Narmada and the Tapi are the only long rivers, which flow west and make estuaries.
• The drainage basins of the peninsular rivers are comparatively smaller in size

The Narmada Basin

• The Narmada rises in the Amarkantak hills in Madhya Pradesh.
• It flows towards the west in a rift valley formed due to faulting.
• On its way to the sea, the Narmada creates many picturesque locations.
• The ‘Marble rocks’, near Jabalpur, where the Narmada flows through a deep gorge, and the ‘Dhauladhar falls, where the river plunges over steep rocks, are some of the notable ones.
• The Narmada river conservation mission has been undertaken by the government of Madhya Pradesh by a scheme named Namami Devi
• All tributaries of the Narmada are very short and most of these join the main stream at right angles.
• The Narmada basin covers parts of Madhya Pradesh and Gujarat.

The Tapi Basin

• The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh.
• It also flows in a rift valley parallel to the Narmada but it is much shorter in length.
• Its basin covers parts of Madhya Pradesh, Gujarat and Maharashtra.
• The coastal plains between Western Ghats and the Arabian Sea are very narrow.
• Hence, the coastal rivers are short.
• The main west flowing rivers are Sabarmati, Mahi, Bharathappuzha and Periyar.

The Godavari Basin

• The Godavari is the largest Peninsular River.
• It rises from the slopes of the Western Ghats in the Nasik district of Maharashtra.
• Its length is about 1500 km. It drains into the Bay of Bengal.
• Its drainage basin is also the largest among the peninsular rivers.
• The basin covers parts of Maharashtra (about 50 per cent of the basin area lies in Maharashtra), Madhya Pradesh, Odisha and Andhra Pradesh.
• The Godavari is joined by a number of tributaries, such as the Purna, the Wardha, the Pranhita, the Manjra, the Wainganga and the Penganga.
• The last three tributaries are very large.
• Because of its length and the area it covers, it is also known as the Dakshin Ganga.

The Mahanadi Basin

• The Mahanadi rises in the highlands of Chhattisgarh.
• It flows through Odisha to reach the Bay of Bengal. The length of the river is about 860 km.
• Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.

The Krishna Basin

• Rising from a spring near Mahabaleshwar, the Krishna flows for about 1400 km and reaches the Bay of Bengal.
• The Tungabhadra, the Koyana, the Ghatprabha, the Musi and the Bhima are some of its tributaries. Its drainage basin is shared by Maharashtra, Karnataka and Andhra Pradesh.

The Kaveri Basin

• The Kaveri rises in the Brahmagri range of the Western Ghats and it reaches the Bay of Bengal in south of Cuddalore in Tamil Nadu.
• The total length of the river is about 760 km. Its main tributaries are Amravati, Bhavani, Hemavati and Kabini.
• Its basin drains parts of Karnataka, Kerala and Tamil Nadu.
• The river Kaveri makes the second biggest waterfall in India, known as Jog Falls. 
• The hydroelectric power generated from the falls is supplied to Mysuru, Bengaluru and the Kolar Gold Field.
• Besides these major rivers, there are some smaller rivers flowing towards the east.
• The Damodar, the Brahmani, the Baitarni and the Subarnarekha are some notable examples.

LAKES

• Srinagar, Nainital and other tourists places did not have a lake
• There are some lakes which are the result of the action of glaciers and ice sheets, while others have been formed by wind, river action and human activities.
• A meandering river across a floodplain forms cut-offs that later develops into ox-bow lakes.
• Spits and bars form lagoons in the coastal areas, e.g. the Chilika Lake, the Pulicat lake and the Kolleru lake. Lakes in the region of inland drainage are sometimes seasonal;

For example, the Sambhar Lake in Rajasthan, this is a salt water lake. Its water is used for producing salt.

• Most of the freshwater lakes are in the Himalayan region.
• They are of glacial origin.
• The Wular Lake in Jammu and Kashmir, in contrast, is the result of tectonic activity.
• It is the largest freshwater lake in India.
• The Dal lake, Bhimtal, Nainital, Loktak and Barapani- freshwater lakes

Advantages of Lakes-

• Apart from natural lakes, the damming of the rivers for the generation of hydel power has also led to the formation of lakes, such as Guru Gobind Sagar (Bhakra Nangal Project).
• A lake helps to regulate the flow of a river.
• During heavy rains, it prevents flooding and during the dry season, it helps to maintain an even flow of water.
• Can also be used for developing hydel power.
• They moderate the climate of the surroundings; maintain the aquatic ecosystem, enhance natural beauty, help develop tourism and provide recreation

National River Conservation Plan (NRCP)

• The river cleaning programme in the country was initiated with the launching of the Ganga Action Plan (GAP) in 1985.
• The Ganga Action Plan was expanded to cover other rivers under the National River Conservation Plan (NRCP) in the year 1995.
• The objective of the NRCP is to improve the water quality of the rivers, which are major water sources in the country, through the implementation of pollution abatement work.

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Chapter- 4

Climate

• Climate refers to the sum total of weather conditions and variations over a large area for a long period of time (more than thirty years).
• Weather refers to the state of the atmosphere over an area at any point of time.

• The word monsoon is derived from the Arabic word ‘mausim’ which literally means season.
• ‘Monsoon’ refers to the seasonal reversal in the wind direction during a year.
• Climate of India- ‘monsoon’ type.
• In Asia, this type of climate is found mainly in the south and the southeast.
• Most parts of the country receive rainfall from June to September.
• But some parts like the Tamil Nadu coast gets a large portion of its rain during October and November.
• In general, coastal areas experience less contrasts in temperature conditions.
• Seasonal contrasts are more in the interior of the country.
• There is decrease in rainfall generally from east to west in the Northern Plains.
• These variations have given rise to variety in lives of people – in terms of the food they eat, the clothes they wear and also the kind of houses they live in.

CLIMATIC CONTROLS

Latitude

• The Tropic of Cancer passes through the middle of the country from the Rann of Kachchh in the west to Mizoram in the east.
• Almost half of the country, lying south of the Tropic of Cancer, belongs to the tropical area. All the remaining area, north of the Tropic, lies in the sub-tropics.
• Therefore, India’s climate has characteristics of tropical as well as subtropical climates.

Altitude

• India has mountains to the north, which have an average height of about 6,000 metres.
• The Himalayas prevent the cold winds from Central Asia from entering the subcontinent.
• It is because of these mountains that this subcontinent experiences comparatively milder winters as compared to central Asia.

Pressure and Winds

The climate and associated weather conditions in India are governed by the following atmospheric conditions:

Pressure and surface winds;

Upper air circulation; and

Western cyclonic disturbances and tropical cyclones

India lies in the region of north easterly winds.

• These winds originate from the subtropical high-pressure belt of the northern hemisphere.
• They blow southwards, get deflected to the right due to the Coriolis force, and move towards the equatorial low-pressure area.
• Generally, these winds carry little moisture as they originate and blow over land.
• Therefore, they bring little or no rain.
• Hence, India should have been an arid land, but it is not so.
• The pressure and wind conditions over India are unique.
• During winter, there is a high-pressure area north of the Himalayas.
• Cold dry winds blow from this region to the low-pressure areas over the oceans to the south.
• In summer, a low-pressure area develops over interior Asia, as well as, over North- western India.
• This causes a complete reversal of the direction of winds during summer.
• Air moves from the high-pressure area over the southern Indian Ocean, in a south-easterly direction, crosses the equator, and turns right towards the low-pressure areas over the Indian subcontinent.
• These are known as the Southwest Monsoon winds.
• These winds blow over the warm oceans, gather moisture and bring widespread rainfall over the mainland of India.
• The upper air circulation in this region is dominated by a westerly flow.
• An important component of this flow is the jet stream.
• These jet streams are located approximately over 27°-30° north latitude, therefore, they are known as subtropical westerly jet streams.
• Over India, these jet streams blow south of the Himalayas, all through the year except in summer.
• The western cyclonic disturbances experienced in the north and north-western parts of the country are brought in by this westerly flow.
• In summer, the subtropical westerly jet stream moves north of the Himalayas with the apparent movement of the sun.
• An easterly jet stream, called the sub-tropical easterly jet stream blows over peninsular India, approximately over 14°N during the summer months

Coriolis force-

• An apparent force caused by the earth’s rotation.
• The Coriolis force is responsible for deflecting winds towards the right in the northern hemisphere
• and towards the left in the southern hemisphere. This is also known as ‘Ferrel’s Law’.

Jet stream-

• These are a narrow belt of high altitude (above 12,000 m) westerly winds in the troposphere.
• Their speed varies from about 110 km/h in summer to about 184 km/h in winter.
• A number of separate jet streams have been identified.
• The most constant are the mid-latitude and the sub-tropical jet stream.

Western Cyclonic Disturbances-

• The western cyclonic disturbances are weather phenomena of the winter months brought in by the westerly flow from the Mediterranean region.
• They usually influence the weather of the north and north-western regions of India.
• Tropical cyclones occur during the monsoon, as well as, in October – November, and are part of the easterly flow.
• These disturbances affect the coastal regions of the country.

Inter Tropical Convergence Zone-

• The Inter Tropical Convergence Zone (ITCZ,) is a broad trough of low pressure in equatorial latitudes.
• This is where the northeast and the southeast trade winds converge.
• This convergence zone lies more or less parallel to the equator but moves north or south with the apparent movement of the sun.

El Nino-

• This is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current.
• ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas.
• The presence of the El Nino leads to an increase in sea-surface temperatures and weakening of the trade winds in the region.

THE INDIAN MONSOON

Atmospheric Conditions over the Indian Subcontinent in the Month of January

The monsoons are experienced in the tropical area roughly between 20° N and 20° S.

To understand the mechanism of the monsoons, the following facts are important -

(a) The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure.

(b) The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator.

It is also known as the monsoon trough during the monsoon season).

(c) The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean.

The intensity and position of this high-pressure area affects the Indian Monsoon.

(d) The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of low pressure over the plateau at about 9 km above sea level.

(e) The movement of the westerly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer.

• Apart from this, changes in the pressure conditions over the southern oceans also affect the monsoons.
• Normally when the tropical eastern South Pacific Ocean experiences high pressure, the tropical eastern Indian Ocean experiences low pressure.
• But in certain years, there is a reversal in the pressure conditions and the eastern Pacific has lower pressure in comparison to the eastern Indian Ocean.
• This periodic change in pressure conditions is known as the Southern Oscillation or SO.
• The difference in pressure over Tahiti and Darwin in northern Australia is computed to predict the intensity of the monsoons.
• If the pressure differences were negative, it would mean below average and late monsoons.
• A feature connected with the SO is the El Nino phenomenon in which a warm ocean current that flows past the Peruvian Coast, in place of the cold Peruvian current, every 2 to 5 years.
• The changes in pressure conditions are connected to the El Nino.
• Hence, the phenomenon is referred to as ENSO (El Nino Southern Oscillations)

THE ONSET OF THE MONSOON AND WITHDRAWAL

• The duration of the monsoon is between 100- 120 days from early June to mid-September.
• The monsoon arrives at the southern tip of the Indian peninsula generally by the first week of June.
• Subsequently, it proceeds into two – the Arabian Sea branch and the Bay of Bengal branch.
• The Arabian Sea branch reaches Mumbai about ten days later on approximately the 10th of June.
• This is a fairly rapid advance.
• The Bay of Bengal branch also advances rapidly and arrives in Assam in the first week of June.
• The lofty mountains cause the monsoon winds to deflect towards the west over the Ganga plains.
• By mid-June the Arabian Sea branch of the monsoon arrives over Saurashtra-Kuchchh and the central part of the country.
• The Arabian Sea and the Bay of Bengal branches of the monsoon merge over the north- western part of the Ganga plains.
• Delhi generally receives the monsoon showers from the Bay of Bengal branch by the end of June (tentative date is 29th of June).
• By the first week of July, western Uttar Pradesh, Punjab, Haryana and eastern Rajasthan experience the monsoon.
• By mid-July, the monsoon reaches Himachal Pradesh and the rest of the country
• The withdrawal of the monsoon begins in North- western states of India by early September.
• By mid-October, it withdraws completely from the northern half of the peninsula.
• The withdrawal from the southern half of the peninsula is fairly rapid.
• By early December, the monsoon has withdrawn from the rest of the country.
• The islands receive the very first monsoon showers, progressively from south to north, from the last week of April to the first week of May.
• The withdrawal, takes place progressively from north to south from the first week of  December to the first week of January.
• By this time the rest of the country is already under the influence of the winter monsoon.

THE SEASONS

The Cold Weather Season (Winter)

• Begins from mid- November in northern India and stays till February.
• December and January are the coldest months in the northern part of India.
• During this season, the northeast trade winds prevail over the country.
• They blow from land to sea and hence, for most part of the country, it is a dry season.
• Some amount of rainfall occurs on the Tamil Nadu coast from these winds as, here they blow from sea to land.
• In the northern part of the country, a feeble high-pressure region develops, with light winds moving outwards from this area.
• Influenced by the relief, these winds blow through the Ganga valley from the west and the northwest.
• A characteristic feature of the cold weather season over the northern plains is the inflow of cyclonic disturbances from the west and the northwest.
• These low-pressure systems originate over the Mediterranean Sea and western Asia and move into India, along with the westerly flow.
• Although the total amount of winter rainfall locally known as ‘mahawat’ is small, they are of immense importance for the cultivation of ‘rabi’ crops.

The Hot Weather Season (summer)

• Due to the apparent northward movement of the sun, the global heat belt shifts northwards.
• March to May
• The influence of the shifting of the heat belt can be seen clearly from temperature recordings taken during March-May at different latitudes.
• In peninsular India, temperatures remain lower due to the moderating influence of the oceans.
• Towards the end of May, an elongated low-pressure area develops in the region extending from the Thar Desert in the northwest to Patna and Chotanagpur plateau in the east and southeast.
• A striking feature of the hot weather season is the ‘loo’.
• These are strong, gusty, hot, dry winds blowing during the day over the north and North- western India.
• Dust storms are very common during the month of May in northern India.
• This is also the season for localised thunderstorms, associated with violent winds, torrential downpours, often accompanied by hail.
• In West Bengal, these storms are known as the ‘Kaal Baisakhi’.
• Towards the close of the summer season, pre-monsoon showers are common especially, in Kerala and Karnataka.
• They help in the early ripening of mangoes, and are often referred to as ‘mango showers’.

Advancing Monsoon (The Rainy Season)

• By early June, the low-pressure condition over the northern plains intensifies.
• It attracts the trade winds of the southern hemisphere.
• These south-east trade winds originate over the warm subtropical areas of the southern oceans.
• They cross the equator and blow in a south- westerly direction entering the Indian peninsula as the south-west monsoon.
• As these winds blow over warm oceans, they bring abundant moisture to the subcontinent.
• With the exception of the extreme north-west, the monsoon winds cover the country in about a month.
• The inflow of the south-west monsoon into India brings about a total change in the weather.
• Early in the season, the windward side of the Western Ghats receives very heavy rainfall, more than 250 cm.
• The Deccan Plateau and parts of Madhya Pradesh also receive some amount of rain in spite of lying in the rain shadow area.
• The maximum rainfall of this season is received in the north-eastern part of the country.
• Mawsynram in the southern ranges of the Khasi Hills receives the highest average rainfall in the world.
• Rainfall in the Ganga valley decreases from the east to the west.
• Another phenomenon associated with the monsoon is its tendency to have ‘breaks’ in rainfall. Thus, it has wet and dry spells.
• These breaks in monsoon are related to the movement of the monsoon trough.
• For various reasons, the trough and its axis keep on moving northward or southward, which determines the spatial distribution of rainfall.
• When the axis of the monsoon trough lies over the plains, rainfall is good in these parts.
• On the other hand, whenever the axis shifts closer to the Himalayas, there are longer dry spells in the plains and widespread rain occur in the mountainous catchment areas of the Himalayan rivers.
• These heavy rains bring in their wake, devastating floods causing damage to life and property in the plains.
• The frequency and intensity of tropical depressions too, determine the amount and duration of monsoon rains.
• These depressions form at the head of the Bay of Bengal and cross over to the mainland.
• The depressions follow the axis of the “monsoon trough of low pressure”.
• The alternation of dry and wet spells varies in intensity, frequency and duration.
• While it causes heavy floods in one part, it may be responsible for droughts in the other.
• It is often irregular in its arrival and its retreat.
• Hence, it sometimes disturbs the farming schedule of millions of farmers all over the country.

Retreating/Post Monsoons (The Transition Season)

• During October-November, with the apparent movement of the sun towards the south, the monsoon trough or the low-pressure trough over the northern plains becomes weaker.
• This is gradually replaced by a high-pressure system.
• The south-west monsoon winds weaken and start withdrawing gradually.
• By the beginning of October, the monsoon withdraws from the Northern Plains.
• The months of October-November form a period of transition from hot rainy season to dry winter conditions.
• The retreat of the monsoon is marked by clear skies and rise in temperature.
• While day temperatures are high, nights are cool and pleasant.
• Owing to the conditions of high temperature and humidity, the weather becomes rather oppressive during the day.
• This is commonly known as ‘October heat’.
• In the second half of October, the mercury begins to fall rapidly in northern India.
• The low-pressure conditions, over north- western India, get transferred to the Bay of Bengal by early November.
• This shift is associated with the occurrence of cyclonic depressions, which originate over the Andaman Sea.
• These cyclones generally cross the eastern coasts of India cause heavy and widespread rain.
• The bulk of the rainfall of the Coromandel Coast is derived from depressions and cyclones

DISTRIBUTION OF RAINFALL

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Chapter- 5

NATURAL VEGETATION AND WILDLIFE

RELIEF

Land

• Land affects the natural vegetation directly and indirectly.
• The fertile level is generally devoted to agriculture.
• The undulating and rough terrains are areas where grassland and woodlands develop and give shelter to a variety of wildlife.

Soil

• The sandy soils of the desert support cactus and thorny bushes, while wet, marshy, deltaic soils support mangroves and deltaic vegetation.
• The hill slopes with somedepth of soil have conical trees.

CLIMATE

Temperature

On the slopes of the Himalayas and the hills of the Peninsula above the height of 915 metres, the fall in the temperature affects the types of vegetation and its growth, and changes it from tropical to subtropical temperate and alpine vegetation.

Photoperiod (Sunlight)

The variation in duration of sunlight at different places is due to differences in latitude, altitude, season and duration of the day.

Due to longer duration of sunlight, trees grow faster in summer.

Precipitation

• In India, almost the entire rainfall is brought in by the advancing southwest monsoon (June to September) and retreating northeast monsoons.
• Areas of heavy rainfall have more dense vegetation as compared to areas of less rainfall.

1. Tropical Evergreen Forests
2. Tropical Deciduous Forests
3. Tropical Thorn Forests and Scrubs
4. Montane Forests
5. Mangrove Forests

• These forests are restricted to heavy rainfall areas of the Western Ghats and the island groups of Lakshadweep, Andaman and Nicobar, upper parts of Assam and Tamil Nadu coast.
• Areas having more than 200 cm of rainfall with a short dry season.
• The trees reach great heights up to 60 metres or even above.
• Since the region is warm and wet throughout the year, it has a luxuriant vegetation of all kinds — trees, shrubs and creepers giving it a multi-layered structure.
• There is no definite time for trees to shed their leaves.
• Trees- ebony, mahogany, rosewood, rubber and cinchona.
• The common animals found in these forests are elephant, monkey, lemur and deer.
• One horned rhinoceroses are found in the jungles of Assam and West Bengal.
• Besides these animals, plenty of birds, bats, sloth, scorpions and snails are also found in these jungles.

Tropical Deciduous Forests

• Most widespread forests of India
• They are also called the monsoon forests and spread over the region receiving rainfall between 200 cm and 70 cm.
• Trees of this forest type shed their leaves for about six to eight weeks in dry summer.
• On the basis of the availability of water, these forests are further divided into moist and dry deciduous.
• Rainfall between 200 and 100 cm
• Mostly in the eastern part of the country — north- eastern states, along the foothills of the Himalayas, Jharkhand, West Odisha and Chhattisgarh, and on the eastern slopes of the Western Ghats.
• Teak is the most dominant species of this forest.
• Bamboos, sal, Shisham, sandalwood, khair, kusum, Arjun and mulberry are other commercially important species.
• The dry deciduous forests are found in areas having rainfall between 100 cm and 70 cm.
• These forests are found in the rainier parts of the peninsular plateau and the plains of Bihar and Uttar Pradesh.
• Teak, sal, peepal and neem grow.
• A large part of this region has been cleared for cultivation and some parts are used for grazing.
• Animals- lion, tiger, pig, deer and elephant
• A huge variety of birds, lizards, snakes and tortoises

The Thorn Forests and Scrubs

• In regions with less than 70 cm of rainfall
• Found in the north-western part of the country, including semi-arid areas of Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Uttar Pradesh and Haryana.
• Plants- Acacias, palms, Euphorbias and cacti
• Trees are scattered and have long roots penetrating deep into the soil in order to get moisture.
• The stems are succulent to conserve water.
• Leaves are mostly thick and small to minimise evaporation.
• These forests give way to thorn forests and scrubs in arid areas.
• In these forests, the common animals are rats, mice, rabbits, fox, wolf, tiger, lion, wild ass, horses and camels.

Montane Forests

• In mountainous areas, the decrease in temperature with increasing altitude leads to the corresponding change in natural vegetation.
• The wet temperate types of forests are found between a height of 1000 and 2000 metres.
• Evergreen broad-leaf trees, such as oaks and chestnuts predominate.
• Trees- pine, deodar, junipers, birches, silver fir, spruce and cedar
• These forests cover mostly the southern slopes of the Himalayas, places having high altitude in southern and north-east India.
• At higher elevations, temperate grasslands are common.
• At high altitudes, generally, more than 3,60o metres above the sea level, temperate forests and grasslands give way to the Alpine vegetation.
• However, they get progressively stunted as they approach the snow-line.
• Ultimately, through shrubs and scrubs, they merge into the Alpine grasslands.
• These are used extensively for grazing by nomadic tribes, like the Gujjars and the Bakarwals.
• At higher altitudes, mosses and lichens form part of tundra vegetation.
• Animals- Kashmir stag, spotted dear, wild sheep, jack rabbit, Tibetan antelope, yak, snow leopard, squirrels, Shaggy horn wild ibex, bear and rare red panda, sheep and goats with thick hair.

Mangrove Forests

• Found in the areas of coasts influenced by tides.
• Mud and silt get accumulated on such coasts.
• The deltas of the Ganga, the Mahanadi, the Krishna, the Godavari and the Kaveri are covered by such vegetation.
• In the Ganga- Brahmaputra delta, Sundari trees are found, which provide durable hard timber.
• Palm, coconut, keora, agar, etc.
• Royal Bengal Tiger
• Turtles, crocodiles, gharials and snakes

WILDLIFE

approximately 90,000 animal species

2,000 species of birds

They constitute 13% of the world’s total.

There are 2,546 species of fish, which account for nearly 12% of the world’s stock.

It also shares between 5 and 8 per cent of the world’s amphibians, reptiles and mammals.

Elephants- found in the hot wet forests of Assam, Karnataka and Kerala

One-horned rhinoceroses are the other animals, which live in swampy and marshy lands of Assam and West Bengal.

Arid areas of the Rann of Kachchh and the Thar Desert are the habitat for wild ass and camels respectively.

Indian bison, nilgai (blue bull), chousingha (four-horned antelope), gazel and different species of deer are some other animals found in India.

It also has several species of monkeys.

Natural habitat of the Indian lion is the Gir forest in Gujarat.

Tigers are found in the forests of Madhya Pradesh, the Sundarbans of West Bengal and the Himalayan region.

Leopards, too, are members of the cat family.

The Himalayas harbour a hardy range of animals, which survive in extreme cold.

Ladakh- yak, the shaggy horned wild ox weighing around one tonne, the Tibetan antelope, the bharal (blue sheep), wild sheep, and the kiang (Tibetan wild ass)

Furthermore, the ibex, bear, snow-leopard and rare red panda are found in certain pockets.

In the rivers, lakes and coastal areas, turtles, crocodiles and gharials are found.

 

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Chapter- 6

Population

Census

• In India, the first census was held in the year 1872.
• The first complete census, however, was taken in the year 1881.
• Every tenth year

India’s Population Size and Distribution by Numbers

2011- 1,210.6 million, which account for 17.5 per cent of the world’s population.

2011 Census data- Uttar Pradesh with a population size of 199 million is the most populous state of India.

• Population density is calculated as the number of persons per unit area.
• 2011 was 382 persons per sq km.
• Bihar- 1,102 persons per sq km
• Arunachal Pradesh- 17 persons per sq km
• Assam and most of the peninsular states have moderate population densities.
• Hilly, dissected and rocky nature of the terrain, moderate to low rainfall, shallow and less fertile soils have influenced population densities in these areas.
• The Northern plains and Kerala in the south have high to very high population densities because of the flat plains with fertile soils and abundant rainfall.

Processes of Population Change/Growth

• Birth rate is the number of live births per thousand persons in a year.
• In India, birth rates have always been higher than death rates.
• Death rate is the number of deaths per thousand persons in a year.
• The main cause of the rate of growth of the Indian population has been the rapid decline in death rates.
• The third component of population growth is migration. Migration is the movement of people across regions and territories.
• Migration can be internal (within the country) or international (between the countries)

Age Composition

Children (generally below 15 years)

They are economically unproductive and need to be provided with food, clothing, education and medical care.

Working Age (15–59 years)

They are economically productive and biologically reproductive. They comprise the working population.

Aged (Above 59 years)

They can be economically productive though they may have retired. They may be working voluntarily but they are not available for employment through recruitment.

Sex Ratio

• Sex ratio is defined as the number of females per 1000 males in the population.
• The sex ratio in the country has always remained unfavourable to females
• Kerala- 1084 females per 1000 males,
• Puducherry-  1038 females for every 1000 males
• Delhi- 866 females per 1000 males
• Haryana- 877.

Literacy Rates

• According to the Census 2011, a person aged 7 years and above, who can read and write with understanding in any language, is treated as literate.
• Census of 2011- 73 per cent;
• 80.9 per cent for males and 64.6 per cent for females

Occupational Structure

1. Primary activities-Agriculture, animal husbandry, forestry, fishing, mining and quarrying, etc.
2. Secondary activities- Manufacturing industry, building and construction work, etc.
3. Tertiary activities-Transport, communications, commerce, administration and other services.

Adolescent Population

• 1/5^th of the total population of India.
• Adolescents- grouped in the age group of 10 to 19 years.

National Population Policy

• 1952- Family Planning Programme- to promote responsible and planned parenthood on a voluntary basis.
• 2000- National Population Policy (NDP) –

1. for imparting free and compulsory school education up to 14 years of age,
2. reducing infant mortality rate to below 30 per 1000 live births,
3. achieving universal immunisation of children against all vaccine preventable diseases,
4. promoting delayed marriage for girls,
5. and making family welfare a people-centred programme

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