MODULE - 6

India - Physical Features

The physical setting of India

16 Notes

INDIA - PHYSICAL FEATURES

Historically, India is an ancient country, known as Bharatvarsh. It is surrounded by the sea on three sides, separated from the rest of Asia by a lofty mountain chain. Hence, it has become an independent entity called the Indian subcontinent. In size, India is the seventh largest country in the world. It is a vast country characterized by great diversity in its physical feature. Therefore, it is necessary to acquire some knowledge about principal physical features. The students should make themselves familiar with the main aspects of its geography, the broad facts regarding the external relief, mountain systems, plateaus, plains, drainage systems, glaciers, volcanoes etc.

OBJECTIVES After studying this lesson, you will be able to : 

describe the location of India in terms of latitude and longitude;



describe with the help of a map and a globe, the importance of the location of India in terms of neighbouring countries, continents, hemispheres and the Indian Ocean; compare India with other countries in terms of area;



describe the main characteristics of major physiographic divisions;



show the major relief features and rivers of India on an outline map of the country;



compare the Himalayan rivers with those of the peninsular India;



conclude that India’s rich and diverse culture is the result of its varied physical features;



explain how different physiographic divisions are economically complementary to each other.

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Notes

India - Physical Features 16.1 LOCATION, EXTENT AND BOUNDARIES OF INDIA A huge landmass of South Asia is flanked by new fold towering mountains on the northwest, north and northeast. The Arabian sea lies to its southwest, the Bay of Bengal to its southeast and the Indian Ocean to its south. This well defined South Asian landmass is called Indian sub-continent. This sub-continent consists of the countries of India, Pakistan, Bangladesh, Nepal and Bhutan including Sri Lanka, an island narrowly separated by the Palk Strait. India alone covers about three fourths of the area of this sub-continent and has common frontier with each one of them. She along with her five neighbours, forms a clearly identifiable geographical unit, with certain common cultural parameters. Since old times, the country has been known by various names such as Aryavarta, Bharat, Hindustan and lately India. The Indian Ocean or Hind Mahasagar has also been named after India the only country to be so. According to the Constitution of India, the country is known as Bharat or India. India lies wholly in the Northern Hemisphere. The Indian mainland extends between 8°4'N to 37°6' N latitudes and from 68°7' E to 97°25' E longitudes. Thus the latitudinal and longitudinal extent of India is of about 29 degrees. It measures about 3,214 km from north to south, and 2,933 km from east to west. Though the latitudinal and longitudinal extent is almost the same, the actual distances do differ considerably. Why is it so? This is because the east-west distance between two successive meridians of longitude along the equator is at its maximum - 111 km. This, however, goes on decreasing as one moves from the equator to the poles, where it is zero. This is because all the meridians of longitude merge in a single point at the poles - both North and South. On the other hand, the north-south distance between any two successive parallels of latitude along any meridian of longitude remains almost uniform, i.e., 111 km. The following table may further clarify this point: Degrees of Latitude

0

Distance between two successive longitudes in kms. 111

10

20

109.6 104.6

30

40

50

60

96.4

85.4

71.7 55.8

70

80

90

38.2

19.4

0

A glance at the globe should help to convince this point. The northern most point of the Indian mainland lies in the state of Jammu and Kashmir and the southern most point is Kanyakumari in Tamilnadu. However, the southern most point of the country as a whole lies further south in Andaman and Nicobar Islands. It is now called Indira Point. It is situated at 6°30'N latitude. The westernmost point of lndia lies in Gujarat and the eastern most in Arunachal Pradesh. Let us see the impact of such large latitudinal extent upon the lives of the people of India. The northern parts of the country are quite far off from the equator. Therefore, the rays of the sun strike those parts more obliquely. Consequently, this part 2

GEOGRAPHY

India - Physical Features of the country receives lesser amount of insolation and has cold climate unlike the southern parts. Secondly, the difference between the length of day and right in southern most part of India is much less only about 45 minutes as they are situated near the equator, This difference between day and night in the northern parts of India steadily goes on increasing till it becomes as much as 5 hours. The Tropic of Cancer passes almost halfway through the country. Thus half of the country to the south of the Tropic of Cancer is situated in the Tropical or Torrid zone and the other half lying north of the Tropic of Cancer falls in the Sub-tropical zone.

MODULE - 6 The physical setting of India

Notes

The earth takes 24 hours to complete one rotation on its axis. The Sun rises first in the east and then in the west because the earth rotates from west to east. The earth’s longitudinal expanse of 360° is thus covered in 24 hours, at the pace of 15° per hour. As the longitudinal extent of India is nearly 29°, the real time difference in India between its eastern and western extremities is roughly of two hours. While at the eastern extremity of India the day may have just broken out, the western extremity would take nearly another two full hours to do so. To iron out this big chunk of time difference, India, like all other countries of the world, follows the local time of its relatively central meridian as the standard time for the whole country. For the convenience of all, each country chooses its standard meridian in a multiple of 7°30'. Accordingly, the standard meridian of India has been chosen to be 82°30' E. The north-central part of India is broad while the southern part tapers down towards the Indian Ocean in the south. Thus, the northern part of the Indian Ocean has been divided into two, by the sheer presence of Indian Peninsula. The western part of northern Indian Ocean is called the Arabian Sea while the eastern part is called the Bay of Bengal. The total length of the coastline of India including the island groups is about 7,516.6 km. The Palk Strait separates Indian mainland from Sri Lanka. Structurally, Sri Lanka is an extension of the peninsular block of India. 16.2 SIZE India accounts for 2.42 per cent of the world’s total land area; whereas it sustains 16 per cent of the world population. You will know more about it in lesson No. 26 on population of India. The land frontiers of India measure 15,200 km. Pakistan, Afghanistan, China, Nepal, Myanmar and Bangladesh share common boundaries with India. The kingdom of Bhutan is situated in the Eastern Himalaya. It is a small country and the responsibility of its defence rests with India. Most of our boundary with Pakistan and Bangladesh is almost man-made. There is no mountain range or river to form a natural boundary. The international boundary of India passes through a variety of landforms - barren desert lands, lush green agricultural fields, gushing rivers, snow clad mountains as well as densely forested mountain ranges. The defence of such an international boundary passing through various GEOGRAPHY

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Notes

India - Physical Features kinds of terrains is certainly a difficult job. An Indian soldier is, therefore, exposed to various types of extremely hostile conditions on the course of his duty. Sometime, he is posted on the icy cold glaciers. At times he has to bear the wrath of the burning sun and he has to face in the hot sands of the desert. Often he is posted in the marshy, riverine, rainy and thickly forested tracts of the northeast. Our country has to spend crores of rupees daily for the defence of such a long and inhospitable boundary that passes through various kinds of terrain. 

India stands at the head of the Indian Ocean that spans the continents of Asia, Africa and Oceania providing further links to other continents through the Pacific Ocean and the Atlantic Ocean.



In the Indian subcontinent, India is the only country to share its land frontiers with every member country of the subcontinent.



In area India is the seventh largest country in the world but in population it stands next only to China.



The variation in local time between the eastern and western extremities of India is of two hours. This has been minimised to a certain extent by adopting 82°30' E longitude as the Standard Meridian of India for calculating Indian standard time which we follow through our watches.

INTEXT QUESTIONS 16.1 1.

Name the countries which share the common land frontiers with India. ______________________________________________________

2.

Between which latitudes and longitudes is India situated? ______________________________________________________.

3.

4.

Which is the southern most point of India? Select the correct alternative. (a) Kanyakumari

(b) Rameshwaram

(c) Indira Point

(d) Kavaratti

Which is the Standard Meridian of India? Select the correct alternative. (a) 68°7' E (b) 97°25’E (c) 82°30' E (d) 800E

5.

Broadly by how many hours does the local time of the eastern most point of India differ from that of the westernmost point? _____________________

16.3 PHYSIOGRAPHIC DIVISIONS OF INDIA India is a land of physical diversities. Almost all types of picturesque and breath taking landforms are found here. According to one estimate, 29.3 per cent of area of India is occupied by mountains and hills, 27.7 per cent by plateaus and 43 per cent by plains. 4

GEOGRAPHY

India - Physical Features From a physiographical point of view, India can be divided into following four regions: 1. 2. 3. 4.

Great Northern Mountains Great Northern Plains Great Indian Plateau and Coastal Plains and Islands.

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Notes

Let us know more about these physiographic divisions. 16.4 THE GREAT NORTHERN MOUNTAINS They include the mountains and plateaus of northern Kashmir, the Himalayas proper and the hills of Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura and Meghalaya. They are divided into three groups. They are (i) The Himalayas (ii) The Trans-Himalayas (iii) Purvachal or the hills of the North-East. (i) The Himalayas This is the highest mountain range of the world. It extends in the shape of an arc for a distance of about 2500 km from west to east along the northern boundary of India between the Indus gorge in Jammu and Kashmir in the west and Brahmputra gorge in Arunachal Pradesh in the east. The breadth of the Himalayas ranges between 400 km in the west to 150 km in the east. The area covered by this mountain system is about 5 lakh square km. It has three major ranges. These ranges are separated by deep valleys and plateaus. The southern slopes of Himalayas facing India are steeper and those facing the Tibetan side are generally gentler. In the east, Himalayas rise almost abruptly from the plains of West Bengal and Assam. That is why two of the highest peaks of Himalayas, Mt. Everest (in Nepal) and Kanchenjunga are not very far from the plains. On the other hand, the western part of Himalayas rises rather gradually from the plains. Hence, the higher peaks in this part are farther from the plains and a number of ranges lie between the plains and high peak. The high peaks of this part such as Nanga Parbat, Nanda Devi and Badrinath are very far from the plains. Three parallel ranges can be identified in the Himalayas. These are (a)

Himadri,

(b)

Himachal and

(c)

Siwalik

(a)

Himadri (Greater Himalaya) : This is the northern most and the highest range of the Himalayas. This is the only range of the Himalaya which main-

GEOGRAPHY

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Notes

India - Physical Features tains its continuity from west to east. The core of this range is made up of granite rocks and flanked by metamorphic and sedimentary rocks. The extent of this range is between the Nanga Parbat peak (8126 m.) in the west and Namcha Barva peak (7756 m.) in the east. The average height of this range from sea level is about 6100 metres. Over 100 peaks have a height of more than the average height of the range. The highest peak of the world, Mount Everest, (8848 m) is situated in this range. Kanchenjunga, Makalu, Dhaulagiri, Annapurna are some of the other peaks having a height of more than 8000 metres. Kanchenjunga is the highest peak of Himalayas in India. The Himadri range is snow clad throughout the year. There are a number of large and small glaciers. After melting of snow and ice, their water falls in the rivers of northern India making them perennial throughout the year. Gangotri and Yamunotri are good examples of such glaciers.

Fig. 16.1 : Physiographic Divisions of India

6

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India - Physical Features The Himadri range can be crossed through some passes like Zojila, Shipkila, Niti, Nathula etc. (b)

Himachal (Lesser or Middle Himalaya) : It is located southwards of Himadri. The breadth of Himachal range is 60 to 80 km and the height varies from 1000 metres to 4500 metres. Some of the peaks of this range have a height of more than 5000 metres. This range is highly dissected and uneven. Rocks in this zone have been metamorphosed due to violent thrusts and compression. Therefore, this range mainly consists of metamorphosed rocks. The gentle slopes of the eastern part of this range are covered with dense forests. The south facing slopes of other parts of this range are very steep and generally devoid of any vegetation. The north facing gentle slopes of this range are covered by dense vegetation.

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Notes

Pir Panjal in Jammu and Kashmir and Dhauladhar in Himachal Pradesh are the local names of this range. The beautiful valley of Kashmir extends between the Pir Panjal and Himadri ranges. The famous valley of Kullu and Kangra are also a part of Himachal ranges. Most of the hill towns or resort towns are located in the Himachal range. Shimla, Nainital, Mussouri, Almora and Darjeeling are some such famous hill towns. There are a number of beautiful lakes around Nainital. (c)

Siwalik (Outer Himalaya) : The southern most range of Himalayas is known as Siwalik. The Himadri and Himachal ranges of the Himalayas have been formed much before the formation of Siwalik range. The rivers rising in the Himadri and Himachal ranges brought gravel, sand and mud along with them, which was deposited in the rapidly shrinking Tethys Sea. In course of time, the earth movements caused folding of these relatively fresh deposits of sediments, giving rise to the least consolidated Siwalik range. The average height of the Siwalik range is very low, about 600 metres only. There are some broad valleys in between the Himachal and the Siwalik ranges. These valleys are known as ‘duns’. Dehradun valley is one of the best examples.

(ii)

The Trans-Himalayan ranges There are some mountain ranges to the north of the Himadri in Jammu and Kashmir. The range extending to the north of the Himadri and running parallel to it is called the Zaskar range. North of Zaskar range is the Ladakh range. The river Indus flows towards northwest between Zaskar and Ladakh range. Many scholars treat Zaskar and Ladakh ranges as parts of the Great Himalayas and include them in Kashmir Himalayas. North of the Ladakh range lie the Karakoram. The name of the Karakoram in Sanskrit literature is Krishnagiri, K2 (8611m) is the highest peak of the Karakoram Mountains. This is the second highest peak of the world, next only to Mt. Everest. Ladakh plateau is situated in the north eastern part of the state of Jammu and Kashmir. This plateau is a very high and arid. It forms one of the remote areas of our country.

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MODULE - 6 The physical setting of India

India - Physical Features (iii) Purvachal Purvachal is the name given to all the hills of north east India beyond Brahmaputra gorge. The average height of these hills from sea level is 500 to 3000 metres. These hills are located in Southern Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura and Meghalaya. Mishmi, Patkoi Bum, Naga, Manipur, Mizo(Lushai) and Tripur are the major hilly ranges of this region. Meghalaya Plateau is also part of these hills of the north eastern region. This plateau includes the hills of Garo, Khasi, and Jaintia. Structurally, however, it is a part of Peninsular India.

Notes

 The Himadri, the Himachal and the Siwalik are three major ranges of the

Himalayas.  The Zaskar, the Ladakh and the Karakoram along with their eastern exten-

sion, Kailash in Tibet are the trans Himalayan ranges.  Mishmi, Patkoi Bum, Naga, Manipur, Mizo, Tripur etc. are the hill ranges of

Purvachal.

INTEXT QUESTIONS 16.2 1.

Select the correct alternative. (i)

Which is the highest mountain peak of the world? (a) K2 (b) Kanchenjunga (c) Mt. Everest (d) Namcha Barva. __________________________________________________

(ii)

Which is the highest peak in India? (a) Annapurna (b) Nanga Parbat (c) K2 (d) Nanda Devi __________________________________________________

2.

Name three mountain ranges of the Himalayas (1)________________(2)______________(3)__________________

3.

Which mountain is referred to as Krishnagiri in Sanskrit literature? _______________________________________________________

4.

Name the most important Trans-Himalayan mountain range in Jammu & Kashmir along with its eastern extension in Tibet. _______________________________________________________

16.5 THE GREAT NORTHERN PLAINS This plain extends from west to east, between Himalayas in the north and Great Indian Plateau in the south. The plain extends from the arid and semi-arid areas of 8

GEOGRAPHY

India - Physical Features Rajasthan in the west to Brahmputra valley in the east. The area of this plain is more than 7 lakh square km. This plain is very fertile and a very sizeable part of the Indian population lives in innumerable villages and several big cities in this region. This plain is made up of the soils brought down and deposited by the rivers flowing from the Himalayas in the North and the Great Indian plateau in the South. The rivers have been depositing their sediments in this plain over millions of years. Therefore, the alluvium in this plain is quite a few hundred metres deep. In some of the parts, the depth of the sediments is as much as 2000 to 3000 metres.

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Notes

This plain is almost dead flat. Its average height is 200 metres above the mean se level. Due to a very gentle slope towards the sea, the rivers in this plain flow very leisurely and at times even sluggishly. The slope from Varanasi upto the mouth of Ganga is only 10 cm. per km. The land around Ambala is a bit more elevated. However, it acts as a water divide between the two major river basins - the Satluj in the west and the Ganga in the east. Rivers lying eastwards of this water divide flow into the Bay of Bengal while those west of it flow into the Arabian Sea. The relatively higher part of the plain is called bangar. This area is never covered with flood water of the rivers. Contrary to this, the comparatively lower area is called the khadar. This area is flooded by streams almost every year. Khadar area is know as bet in Punjab. There is a strip of plain about 10-15 km broad along the outer slopes of the Siwaliks in Punjab, Haryana and Uttar Pradesh. This region is known as ‘bhabar’. This strip of bhabar is made of gravel and coarse sand. The smaller streams disappear under ground in the ‘bhabar’ region during the summer season and their water surfaces again after crossing the bhabar. This water accumulates in the strip of plain about 15 to 30 km wide and extends to the south of bhabar. Accumulation of this water makes the land marshy. This marshy land is called the terai. Many parts of the terai have been reclaimed, for agricultural purposes. The great Northern Plain can be divided into four parts: (i) Western plain (ii) North Central plain (iii) Eastern plain and (iv) Brahmputra plain. (i)

Western Plain : This region includes the Rajasthan desert and bangar region lying to the west of Aravali ranges. The desert is partly rocky and partly sandy. In the ancient period, the perennial streams - Saraswati and Drishadvati - flowed through this region. This region includes the fertile area of Bikaner. River Luni flows through this bangar region and falls into the Rann of Kutchchh. The famous salt water lake of Sambhar is situated in this part of the plain.

(ii)

North Central Plain: This plain extends over Punjab, Haryana and Uttar Pradesh. The part of this plain extending into Punjab and Haryana has been formed by the alluvium brought by rivers Satluj, Beas and Ravi. This is a very fertile area. The part of this plain lying in Uttar Pradesh is made up of

GEOGRAPHY

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India - Physical Features

The physical setting of India

Notes

the deposits laid down, by the rivers like, Ganga, Yamuna, Ramganga, Gomati, Ghagra and Gandak. This part of plain is highly fertile and has been the cradle of Indian civilization and culture. (iii) Eastern Plain: This part of the great plains covers the middle and the lower Ganga valley lying in the states of Bihar and West Bengal. Ganga flows through the middle of this plain in Bihar. Ghagra, Kosi and Gandak join Ganga from the north while Son joins from south. On entering West Bengal the plain widens further extending from the foot hills of the Himalayas upto the Bay of Bengal. The southern part of the plain is delta region. Ganga is divided into several distributaries in the delta region. Hooghly is the best example of a distributary of Ganga. This part of the plain is indeed very fertile and more rainy. (iv) Brahmputra Plain: The northeastern part of the Great Indian Plain extends into Assam. This plain has been formed by deposition of alluvium brought down by river Brahmputra and its tributaries. Brahmputra is highly prone to devastating floods at regular intervals. After the floods, the river generally changes its course. This process has led to the formation of various islands in the river. Majuli (1250 square kilometer) in the Brahmputra river is the world’s largest river island. This part is also very fertile. It is surrounded by hills from three sides. Bangladesh is situated on this plain and the delta jointly formed by Ganga and Brahmaputra and their distributaries.  The great Northern Plains have been formed by alluvium deposits brought

by rivers flowing from Himalayas and the Great Indian Plateau.  This plain is dead flat, with almost negligible slope.  The plain is of two types bangar and khadar.  The Great Northern Plain can be divided into four parts - Western Plain,

North Central Plain, Eastern Plain and Brahmputra Plain.

INTEXT QUESTIONS 16.3 1.

What is the maximum depth of alluvium deposits in the Great Northern Plain? _______________________________________________________

2.

What is meant by the term ‘bangar’? _______________________________________________________

3.

In which three states does the bhabar region extend? (a) ______________(b)______________(c)______________

10

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India - Physical Features 4.

Which two perennial rivers flowed through the Western Plain in ancient times? (a) ________________________(b)_______________________

5.

Name four rivers flowing through the North Central Plain

MODULE - 6 The physical setting of India

(a)____________________________ (b)______________________ (c)____________________________(d)______________________

Notes

16.6 THE GREAT INDIAN PLATEAU The Great Indian Plateau lies to the South of the Great Northern Plains. This is the largest physiographic division of our country. It covers an area of about 16 lakh square km, i.e., about half of the total area of the country. It is an old rocky plateau region. The topography consists of a series of plateaus and hill ranges interspersed with river valleys. Aravalli hills mark the north-western boundary of the plateau region. Its northern and north-eastern boundary is marked by the northern edge of the Bundelkhand Plateau,Kaimur and Rajmahal Hills. The Western Ghats (Sahyadry) and the Eastern Ghats mark the western and eastern boundaries respectively of this Great Plateau. Most of the area of the plateau has a height of more than 400 metres above sea level. The highest point of plateau region is the Anaimudi peak (2965 m). The general slope of this plateau is towards east. The Great Plateau is the part of very ancient landmass, called Gondwana land. From the earliest time it has been above the level of the sea. Therefore, it has been subjected to large scale denudation. Its mountains are generally of relic type. They are composed of very hard rocks, which have withstood the ravages of denudation more effectively than the surrounding regions. Because of their old age, all the rivers have almost attained their base level and have built up broad and shallow valleys. The dominant rock formations, especially those in the southern parts, are of metamorphic origin with frequent occurrences of granites. River Narmada divides the peninsular block of India into two parts. The region lying to the north of the Narmada is called the Central Highlands and the region lying to the south of Narmada is called the penninsular plateau, more commonly referred to as the Deccan Plateau. A glance at the map would point out that barring Narmada and Tapti all the major rivers lying to the south of the Vindhyas flow eastwards to fall into the Bay of Bengal. The westward flow of Narmada and Tapi is assigned to the fact that they have been flowing through faults or rifts which were probably caused when the Himalayas began to emerge from the Tethys Sea of the olden times. (i)

The Central Highlands: It extends between river Narmada and Great Northern Plains. The Aravallis form the west-northwestern edge of the Central Highlands. These hills extend from Gujarat, through Rajasthan to Delhi in the northeasterly direction for a distance of about 700 km. The height of

GEOGRAPHY

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these hills is about 1500 metres in southwest while near Delhi they are hardly 400 metres high. The highest peak of the Aravalli hills is Gurushikhar (1722 m) near Mt. Abu. Mt. Abu on the border of Gujarat and Rajasthan is a beautiful hill station. The region to the east of Aravallis is the highly dissected and uneven. Malwa plateau forms the dominant part of the Central Highlands.

Notes

It lies to the southeast of Aravallis and to the north of Vindhyachal Range. River Chambal, Betwa and Ken drain the Malwa Plateau before they join Yamuna. The part of the Central Highlands which extends to the east of Malwa Plateau is known as Bundelkhand and is further followed by Baghelkhand and the well known Chhotanagpur Plateau. Vindhyachal Range forms the southern edge of Malwa Plateau. The Mahadeo Hills, Kaimur Hills and Maikal Range lie towards further east. The slope of Vindhayachal Range towards Narmada valley is absolutely steep and forms escarpments. It only confirms that Narmada flows through a rift valley. This range has very few passes. Due to this fact the Vindhyas acted as a barrier between northern and southern parts of India for a long time in the past. The valley of Narmada is situated between the Satpuras and the Vindhyas. River Narmada flows from east to west in this valley and falls into the Arabian Sea. This valley has been formed due to the subsidence of the land mass between the Vindhyas and the Satpuras. (ii)

The Peninsular Plateau (Deccan Plateau) : This physiographic division is the largest region of the Great Indian Plateau. The shape of this plateau is triangular. One of the sides of this triangle is marked by the line joining Kanya Kumari with Rajmahal Hills and this line passes through the Eastern Ghats. The second arm is marked by the Satpura Range, Mahadeo Hills, Maikal Range and the Rajmahal Hills. The third arm is marked by the Sahyadris (Western Ghats). The area of this Penninsular Plateau is about 7 lakh square km and the height ranges from 500 to 1000 metres above sea level. The Sahyadri Range forms the sharp edge of the Penninsular Plateau. Its long escarpments running parallel to the Arabian Sea coast are simply breath taking. Due to its location on the western margin of the Penninsular Plateau, the Sahyadri Range is also called Western Ghats. The word ‘Ghat’ also means a step like mountain. Therefore, this English name of the Sahyadris is meaningful. The height of the Sahyadris increases from north to south. Anaimudi peak (2695 m) situated in Kerala is the highest peak of southern India. Anaimudi is a sort of tri-junction of the Annamalai Range, the Cardamom Hills and the Palani Hills. Kodai Kanal is a beautiful hill resort situated on the Palani Hills. Eastern Ghats running from southwest to northeast form the eastern edge of the Penninsular Plateau. This range is known as poorvadri also. The Eastern Ghats joins the Sahyadris at the Nilgiri Hills bordering Karnataka and

12

GEOGRAPHY

India - Physical Features Tamilnadu. Udagamandalam (Ooty) situated on the Nilgiris is the famous hill station of South India and lies in Tamil Nadu. Once it was the summer resort of the Governor of Madras Presidency. The Eastern Ghats are not continuous like the Sahyadris. Mahanadi, Godavari, Krishna, Pennar and Kaveri rivers have dissected this range at many places. The plateau region between the Sahyadris and the Eastern Ghats is known by numerous local names in different regions. Telangana which extends in Andhra Pradesh is the name of such a plateau. River Damodar flows through the Chhotanagpur Plateau. The valley of this river is famous for its huge coal deposits. Besides coal, this region is a store house of a number of other minerals.

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Notes

 The shape of the Great Plateau is triangular.  It can be divided into two major parts. The Central Higlands and the Penin-

sular Plateau.  Aravallis, Vindhyas, Sahyadris, Poorvadris, Annamalai, Cardamom, Palani

Mahadeo, Maikal and Satpuras are the major hills of the Great Plateau.  Chambal, Narmada, Tapi, Mahanadi, Godavari, Krishna and Kaveri are

the major rivers of the Great Plateau.

INTEXT QUESTIONS 16.4 1.

Select the correct alternative (i)

Which is the highest peak of southern India? (a) Doda Betta (b) Anaimudi (c) Mahabaleshwar (d) Guru Shikhar __________________________________________________

(ii)

Which river flows through a rift valley? (a) Narmada (b) Chambal (c) Godavari (d) Pennar __________________________________________________

2.

Name two rivers flowing through Malwa plateau. (a) _______________________(b)________________________

3.

On which hills is Kodaikanal situated? ______________________________________________________

4.

Name the famous hill station situated on the Aravallis. ______________________________________________________

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India - Physical Features 16.7 COASTAL PLAINS The Great Plateau of India is surrounded by plains on all sides. In the north lies the Great Northern Plain and in south, along the east and west lie the Coastal Plains.

Notes

East Coastal Plain extends along the coast of the Bay of Bengal from Ganga Delta in the north to Kanyakumari in the south. This plain is broader than the western coastal Plains. This plain includes the deltas of the rivers Mahanadi, Godavari, Krishna and Kaveri. Chilka, Pulicat and Koluru lakes are the famous lagoons of this plain. These lakes have been formed by enclosing small parts of the Bay of Bengal behind sand bars. Lake Chilka is situated south of the delta of Mahanadi. The lake measures 75 km in length. Lake Pulicut is situated north of Chennai city. Koluru lake is situated between the deltas of the Godavari and Krishna rivers. The east coastal plain is fertile where rice grows in plenty. West Coastal Plain extends along the Arabian Sea from the Rann of Kutchch in the north to Kanyakumari in the south. Except for the Gujarat plain, the western coastal plains are narrower than the eastern coastal plain. From southern Gujarat upto Mumbai this plain is comparatively broader, but it narrows southwards of Mumbai. Occasionally rocky domes and hills are visible in the plains of Gujarat, the Rann of Kutchch and the plains of Kathiawar. The plains of Gujarat are made up of black soil. The coastal strip extending for about 500 km between Daman in the north and Goa in the south is called Konkan. This region is highly dissected and the coast line is indented or irregular with several natural harbours. A number of small and seasonal rivers flow through this region. The coast from Goa to Mangalore is called the Karnataka coast. The coast from Mangalore upto Kanyakumari is called the Malabar coast. Here the coastal plain is wider. There are a number of long and narrow lagoons. 80 km. long Vembanad is an example of its kind. Kochi port is situated on one of the lagoons. 16.8 INDIAN ISLANDS There are two small groups of islands. One of these situated in the Bay of Bengal, off the coast of Myanmar is known as the Andaman and Nicobar Islands. The other is known as Lakshadweep and situated in Arabian Sea, off the coast of Kerala. The Andaman Islands consists of (i) North, (ii) Middle, (iii) South and (iv) Little Andaman Islands. Port Blair is the capital city of the entire Union Territory and is located in South Andaman Island. This island group is separated by the Ten Degree Channel. To its south are situated the Nicobar Islands. They include Car Nicobar, Little Nicobar and Great Nicobar Islands from north to south. The southern most point of the Indian Union lies in Great Nicobar Island and has been named after Indira Gandhi. These islands represent a submerged chain of mountains. The Barren Island in the Andamans is India’s only active volcano. These islands act as a naval and air outpost of our country in view of its strategic location. This island group faces seven countries - Bangaladesh, Myanmar, Thailand, Malaysia, Singapore, Indonesia and Sri Lanka.

14

GEOGRAPHY

India - Physical Features Lakshadweep Islands are situated in the Arabian Sea, off the coast of Kerala. All these islands are of coral origin. They have been built up by corals, the microscopic polyps. All these islands are very small in size. The largest island among these, the Minicoy, has an area of 4.5 square km only. Kavaratti is the capital city of this island group.  The West Coastal plains extend along the Arabian Sea coast.

MODULE - 6 The physical setting of India

Notes

 The East Coastal Plains extend along the coast of the Bay of Bengal.  The East Coastal Plains are broader than the West Coastal Plains.  Lakshadweep Islands are situated in the Arabian Sea, off the coast of Kerala

and the Andaman & Nicobar Islands are situated in the bay of Bengal, off the coast of Myanmar. Their location is highly strategic.

INTEXT QUESTIONS 16.5 1.

Which of the coastal plains of India is broader than the other? ______________________________________________________

2.

Name two lagoons on the Eastern Coastal plain. (a)

______________________ (b) _____________________

3.

Which lake is situated between the deltas of the Godavari and the Krishna rivers? _________________________________________________

4.

Name the two places asociated with the northern or southern extremities of the Konkan coast respectively. _______________________________________________________

5.

Which Indian group of islands is of coral origin? Select the correct alternative. (a) Andaman (b) Nicobar (c) Lakshadweep (d) Barren _______________________________________________________

16.9 DRAINAGE SYSTEM The drainage pattern or system of an area refers to the system of flow of surface water mainly through the rivers and basins forms. The drainage system studies streams and the directions in which they carry the surface water of an area. The drainage system is related to a number of factors, for example slope of land, geological structure, amount of volume of water and velocity of water. The surface run off of India is carried by a number of small and large rivers. The drainage system of country can be studied with reference to two parts Northern India and Southern India.

GEOGRAPHY

15

MODULE - 6 The physical setting of India

Notes

India - Physical Features (a) Drainage System of North India Himalayas play an important role in the drainage system of the North India. This is because the rivers of North India have their sources in these mountains and beyond. These rivers differ from those of South India as they are still deepening their valleys rather rapidly. The debris eroded by these rivers are carried to the plains and seas and deposited there. This deposition is caused by the reduced velocity of river waters in the plains and deltas for want of necessary slope. The Great North Indian plain has been formed by the silt brought down by these rivers. Some of the Himalayan rivers are older than the Himalayas themselves. As the ranges of the Himalayas had been rising upwards, these rivers were equally busy in downward cutting forming deep gorges and valleys. Consequently, parts of the valleys of these rivers are very deep and gorges have been formed. The depth of the Indus gorge near Bunji (Jammu & Kashmir) is 5200 metres. Sutlej and Brahmaputra have also formed such gorges. The drainage system of Northern India can be further sub-divided into three subsystems Indus System, Ganga System and Brahmaputra System. The major rivers of Indus basin are the Indus, Jhelum, Chenab, Ravi, Beas and Sutlej. The Ganga basin includes Ramganga, Ghaghra, Gomti, Gandak, Kosi, Yamuna along with its southern tributaries, Son and Damodar rivers. The major rivers of Brahmputra basin are Dibang and Lohit in Arunachal Pradesh and Assam, Tista in Sikkim, West Bengal and Bangladesh and Meghna, draining northeastern part of Bangladesh. (b) Drainage System of Southern India The Peninsular India is an ancient landmass. Therefore, the streams flowing through this region are in their old stage. They have almost attained their base level of erosion. Their capacity to erode valleys vertically has almost come to a negligible stage. Now these streams are eroding their sides at a slow pace. This is resulting in broadening of their valleys. Consequently, during flood their waters spread over a large area. It is believed that at the time of Himalayan orogeny, due to the movements associated with the mountain building processes, the Peninsular block had a slight tilt towards east. This is why, barring Narmada and Tapi, all the major rivers of south India flow towards east. Narmada and Tapi, both flow through fault or rift valleys. The major rivers of the drainage system of southern India are Mahanadi, Godavari, Krishna, Pennar, Kaveri and Vaigai. The slope of the northern part of the southern peninsula is towards north. Consequently, some of the streams originating in the Vindhyas, flow towards north and join Yamuna and Ganga. Among these, Chambal, Ken, Betwa, Sind and Son are more important.

16

GEOGRAPHY

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India - Physical Features

The physical setting of India

Notes

Fig. 16.2: Major Rivers of India

The difference between the Himalayan rivers and Peninsular rivers The rivers which have their origin in the Himalayas are perennial. These rivers are fed by the melting of ice and snow lying near the tongue of glaciers of the Great Himalayan Range (Himadri). In the rivers of South India, the flow of water is highly fluctuating. While the rivers are in spate during the monsoons, they are almost dry during the long rainless months. Some of these rivers at many places become totally dry. GEOGRAPHY

17

MODULE - 6 The physical setting of India

Notes

India - Physical Features 16.10

DIVERSITY AND COMPLEMENTARITY OF PHYSIOGRAPHIC DIVISIONS

India possesses a wide variety of landforms and relief features. Its young fold mountains of the north have very bold and sharp features. They include very long as well as tall mountain ranges, towering mountain peaks, high mountain passes and precipitous river valleys. If in one direction lie very steep slopes, on the other there are gentle slopes. If some parts are without thick forests, the others are clad with varied natural vegetation - from tropical rain forests to Alpine grasslands. They rightly boast of large snowfields, glaciers, picturesque water falls along the hanging valleys and glacial lakes like the Dal in Srinagar. The youthful Himalayan rivers prefer to jump, leap and hop forming water falls, rapids and cascades on their way. Equally awe-inspiring are its deep gorges establishing balance between steadily rising mountian ranges on the one hand and silent down cutting action of weighty trans Himalayan rivers like the Indus, Sutlej and Brahamaputra on the other. Not even a handful of countries can boast of such a magestic and maddening beauty of youthful fold mountains. These highest and largest mountain chains of the world have enabled Indian subcontinent to develop its unique culture by acting itself as a physical barrier between the subcontinent and the rest of Asia. Perhaps even more effective is its role as a climatic divide. This physiographic division acts as a store house of snow and water, giving rise to hundreds of perennial rivers to drain and irrigate one of the world’s largest and most fertile plains. In fact the plains themselves are a gift of these mountains and rivers flowing from them. It is also a store house of hydel power, fuel wood, timber, various forest products and medicinal herbs, no excluding some strange wildlife species. No wonder, if this region is able to attract tourists from far and near, both in summer and winter. The Northern Plains are matchless in expanse. These flat or dead level plains are mostly well drained and fairly well irrigated through the use of surface and ground water. The meandering rivers, ox-bow lakes, braided river channels and a maze of distributaries help to break the monotony of these extremely level plains. Once a forest land, it has now been brought under the plough almost fully. The lower parts of the deltas are ribbonned with mangrove or tidal forests. These well watered plains, supported by highly fertile soils, produce varied crops year after year sustaining a very large chunk of the world’s population. They have also been supporting equally large bovine population. They are one of the world’s largest food baskets producing cereals, pulses, oil seeds, vegetables, fruits besides industrial or cash crops like cotton, jute, sugarcane and the like. In sharp contrast with the Northern Mountains and Plains stand the hills of moderate attitude and a highly denuded rocky landscape, representing one of the oldest landmasses of the world - the peninsular block of India. Its rounded hills and flat topped ridges have a beauty of their own. The varied metamorphic and old granite rocks have given rise to hills, plateaus and foliated rocks. Further more, the basalt or Deccan Trap of Western India has its typical flat topped hills and ghat or stairlike

18

GEOGRAPHY

India - Physical Features structures. Its steep wall-like escarpments run for miles and miles without interruption overlooking the Arabian Sea. Their beauty need to be seen and to be believed. This physiographic division is known for millets and various industrial crops such as cotton, sugarcane, coffee and groundnut. More importantly, it is a store house of minerals - specially the ferrous ones and mineral fuels like coal and atomic or radio-active minerals. They have also sizeable hydel power resources. They, thus, provide a sound base to develop both agro-based and mineral-based industries.

MODULE - 6 The physical setting of India

Notes

The coastal strips are ribonned with a coastline which is partly regular and partly indented. The latter has provided spacious natural harbours like Mumbai and Marmagao. The coastal strips and island groups have ideal conditions to tap deep and shallow water fisheries. The coastal plains in the east have very fertile deltas providing rice-bowls. If it is a coast of emergence in the eastern coast then the major part of the western coast is that of submergence. The plains are rocky and highly eroded. Rice, coconuts, rubber, tobacco and spices are some of the agricultural produce. Off-shore oil and natural gas fields have also been located. If the Lakshadweep are of coral origin, the Andaman and Nicobar Islands are the peaks of emerging mountain chain. These islands are of great strategic significance to the defence of the mainland. They face seven different countries across the seas washing their shores - Bangladesh, Myanmar, Thailand, Malaysia, Singapore, Indonesia and Sri Lanka. The islands are known for fishing, forestry and tourism. This is how the great diversity of macro and micro relief features and land forms has contributed to enrich our culture, enhanced agricultural potential to grow almost every crop, lay strong foundations of modern industry making all its physiographic divisions totally inter dependent on one another.

INTEXT QUESTION 16.6 1. 2.

3. 4.

Name any two factors, which influence the drainage system. (a) ______________________ (b) ______________________ Fill in the blanks with appropriate words out of those given in the brackets: (i) Surface run off from Indian territory flows into the __________ in the west and the ___________ in the east. (Indian ocean, Bay of Bengal, Persian Gulf, Arabian Sea) (ii) The two major west flowing rivers of South India are___________ and ___________ (Mahanadi, Kaveri, Narmada, Tapi) Name three rivers of the Great Plateau which flow towards north. (a)_______________ (b)___________________(c)________________ How deep is the gorge of the Indus river near Bunji? _______________________________________________________

GEOGRAPHY

19

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India - Physical Features

The physical setting of India

WHAT YOU HAVE LEARNT

Notes

The Indian subcontinent, flanked by the towering mountains in the north and girdled by the seas and the ocean in the south stands distinct from the rest of Asia. This explains why the subcontinent has been able to develop a distinctive culture of its own. India occupies a dominant position in the subcontinent as it alone claims three fourths of the total population. Also it has fairly long common frontiers with each member of the subcontinent. Being located at the head of the Indian Ocean it is in a very good position to promote trade with the continents of Asia, Africa and Australia. The construction of Suez Canal has brought Europe and North America in its easy reach. India is only at a relatively short distance from the oil-rich countries surrounding the Persian Gulf. The latitudinal extent of the country implies marked variations in the climate of the northern and southern parts of the country. The longitudinal extents is responsible for a time lag of almost two hours between its eastern and western extremities. This, however, has been minimised by adopting 82030' E longitude as the standard meridian of India whose local time is taken to be the standard time for the entire country. In terms of area, India stands seventh in the world but in population it ranks second next only to China. It means there is tremendous population pressure on our limited land and water resources. The physiographic divisions of India are very bold and highly contrasting. In fact, each one of them can be presented as an ideal example of its kind - be it a mountain; a plateau or a plain. Besides adding to the diversity they also stress economic complementarity. They make all these macro regions entirely interdependent on one another, making the whole country a single economic and political entity benefiting each and every part - big or small.

TERMINAL QUESTIONS 1.

Give a brief account of the Himadri Range under the following headings. (a) Location (b) Their average height and length (c) A few major peaks (d) Few prominent glaciers and (e) Major passes - one each from Jammu & Kashmir, Himachal Pradesh and Sikkim.

2.

Differentiate between: (a)

Eastern coastal plains and western coastal plains.

(b) Western ghat and Eastern ghat. (c) 20

The Himalayan rivers and peninsular rivers. GEOGRAPHY

India - Physical Features 3.

Divide the Great Plateau into two physiographic divisions and describe briefly the Central High Lands under the following heading - (a) Aravalli Hills (b) Malwa plateau and its eastern extensions (c) Vindhyachal Range

4.

Write a brief description of Northern Plains, a sub-division of Great Northern Plains of India; under the following headings. (a) Location and extent (b) Major rivers.

5.

Define the following - (a) Standard Meridian of India (b) Rift Valley (c) Drainage System.

6.

Locate the following in two separate outline maps of India.

MODULE - 6 The physical setting of India

Notes

Map I - (a) Himalayas, Karakoram, Zaskar Range, Ladakh Range, Mizo Hills, Sahyadry, Satpura and Vindhyachal Range. Map II - (b) Satluj, Ganga, Brahmaputra, Yamuna, Chambal, Mahanadi, Godavari, Krishna, Kaveri, Narmada and Tapi rivers.

ANSWERS TO INTEXT QUESTIONS 16.1 1. 2. 3. 4. 5. 16.2 1.1 2. 3. 4. 16.3 1. 2. 3. 4. 5. 16.4 1.

Pakistan, Afghanistan, China, Nepal, Myanmar, Bangladesh and Bhutan 8°4' and 37°6' N. Lat., 68°7' and 97°25' E Long. (C) (c) 82°30' About two hours (i) (c) (ii) (c) (1) Himadri (2) Himachal (3) Siwalik Karakoram Karakoram 2000 to 3000 metres Comparatively higher part of the plain. (a) Punjab (b) Haryana (c) Uttar Pradesh (a) Saraswati (b) Drishadvati Yamuna, Ganga, Gomati, Ghagara, Gandak, Ramganga (Any four). (i) (b) (ii) (a)

GEOGRAPHY

21

MODULE - 6 The physical setting of India

Notes

22

India - Physical Features 2. 3. 4. 16.5 1. 2. 3. 4. 5. 16.6 1.

Chambal, Betwa, Parbati, Kali, Sindh (Any two). Palani Hills Mt. Abu (Peak is Gurushikhar) The East Coastal Plain (a) Chilka (b) Pulicat Kolleru Daman (North) and Goa (South) (c)

Slope of land, geological structure, amount of water and velocity of water (Any two) 2. (i) Arabian Sea; Bay of Bengal (ii) Narmada and Tapi 3. Chambal, Parbati, Sind, Betwa, Ken, Son (Any three). 4. 5200 metres. HINTS TO TERMINAL QUESTIONS 1. Refer to the description of Himadri Range in 16.4 2. (a) East coastal plain West coastal plain 1. Extend along the coast of Extend along the coast of Bay of Bengal Arabian Sea 2. Comparatively broad Comparatively narrow 3. There are deltas here No deltas of rivers. (b) Sahyadry (Pashchimi Ghat) Poorvi Ghat 1. Continuous range Broken by a number of rivers draining into the Bay of Bengal 2. Comparatively high Low height 3. Beautiful hill towns No hill towns (c) Himalayan Rivers Rivers of Peninsular India 1. Perennial Seasonal 2. Origin from glaciers Origin from springs 3. Refer to the description of Central High Lands given in 16.6 4. Standard Meridian 82°30' E ; The local time of the standard meridian is considered to be the standard time for the whole country. 6. Rift valley: A valley which has been formed by the sinking of land between roughly parallel faults is called a rift valley. Drainage System: The drainage system refers to the system of flow of surface water or runoff in that area. Thus the drainage system studies the streams and the directions in which they carry the surface water of an area. 7. Refer to the maps given at the end of this lesson showing physical features and location of rivers. GEOGRAPHY

MODULE - 6

Climate of India

The Physical setting of India

17 Notes

CLIMATE OF INDIA

In the previous lesson, we have noted the shape and size of our country along with its latitudinal extent. Not only its physiographic divisions are diverse but also far more contrasting in nature. Each one of these factors has an impact on climatic conditions of India, be it temperature, atmospheric pressure, wind system or precipitation. In this lesson, we will study regional variations in the climatic conditions of India. A search will be made to identify a series of factors responsible for these climatic variations both over space and time. A cycle of seasons would also merit our attention. As our climate is labelled “a monsoon type of climate” we would study the basic concept of monsoons and their typical charateristics. Since, in our country, the climatic variations depends more on rainfall rather than temperature, we would devote some time to study distribution of rainfall.

OBJECTIVES After studying this lesson, you will be able to: 

explain with suitable examples the climatic variations in India (both seasonal and spatial);



name various factors which influence the climate of different parts of India;



explain the concept of monsoon and the way it is caused;



discuss the typical characteristics of monsoons;



state the climatic conditions during different seasons;

17.1 CLIMATIC VARIATIONS IN INDIA You have studied the shape, size, location and latitudinal extent of India. You have also noted the sharply contrasting relief features of India. This has created regional diversities in climatic conditions. The climatic conditions of southern India are a bit GEOGRAPHY

23

MODULE - 6 The Physical setting of India

Notes

Climate of India different from those of the northern parts with respect to temperature, rainfall and commencement as well as duration of different seasons. Now, let us have a closer look at these climatic variations. During June, the north western plains experience high temperature around 45°C when areas of Rajasthan desert record day temperatures around 55°C, while the temperatures around Gulmarg or Pahalgam in Kashmir are hardly around 20°C. Similarly, in the month of December, the people of Kargil or Dras(in Jammu & Kashmir) experience biting cold because the night temperatures drop to -40°C, while the inhabitants of Thiruvananthapuram experience temperatures around 27° C (Table 17.1) The range of temperature increases as one moves away from coastal areas to interior parts of the country. As a result, the people living along Konkan and Malabar coasts do not experience extremes of temperatures or marked change in seasons. On the other hand, people living in north western parts of India, experience sharp seasonal contrasts. The diversity in rainfall distribution is equally striking. Mausimram, near Cherrapunji in Meghalaya, receives about 1080 cm of rainfall annually, while Jaisalmer in the desert of Rajasthan receives only 20 cm of annual rainfall. The northeastern parts and the coastal plains of Orissa and West Bengal experience spells of heavy rain during July and August while the Coromondel coast of Tamilnadu receive very meager rain during these months (Table 17.1) Have a close look at Figure17.1 and 17.2 which show the dates of onset and withdrawal of Southwest monsoons respectively. This will help you to understand the difference in the duration of rainy season in different parts of India. You will come to the conclusion that the duration of rainy season is the shortest in Northwest India and longest in the South and North eastern parts of the country. 



The shape, size, location, latitudinal extent of the country and its contrasting relief have resulted in diverse climatic conditions in different parts of India. Climatic diversity is reflected in regional variations in temperature, amount of rainfall and commencement as well as duration of seasons.

INTEXT QUESTIONS 17.1 1.

2.

24

Name two places in India - one experiencing the highest and the other the lowest temperatures. (a) ______________________(b) ______________________ Study the Table 17.1 and answer the following questions: (i) Name the station which has the most equable climate. (ii) Which station has the highest range of temperature ? (iii) Which station has the highest temperature in GEOGRAPHY

MODULE - 6

Climate of India (a) February

(b) April

(c) June

(d) August

The Physical setting of India

(iv) Name the four most rainy months in India. (a) _________ (b) _________ (c) _________ (d) _________ (v)

Notes

Name a place in India which has the lowest rainfall.

Table 17.1: Mean Monthly Temperature and Rainfall in Major Meteriological Centres in India T=Temperature (in Celsius) and P=Precipitation (in mm) Station

T/P

J.

F.

M.

A.

M.

J.

J.

A.

S.

O.

N.

D.

Leh

T. P.

-8 10

-7 8

-1 8

9 5

10 5

14 5

17 13

17 13

12 8

6 5

0 0

-6 5

Shilong

T. P.

10 14

11 29

16 56

19 19 21 146 295 476

21 359

21 343

20 302

17 188

13 36

10 10

Kolkata

T. P.

20 12

22 28

27 34

30 30 30 51 134 290

29 331

29 334

29 253

28 129

24 27

20 4

Delhi

T. P.

14 21

17 24

23 13

29 10

34 10

35 68

31 186

30 170

29 125

21 14

20 2

15 9

Jodhpur

T. P.

17 5

19 6

25 3

30 3

34 10

34 31

31 108

29 131

29 57

27 3

22 2

18 2

Mumbai

T. P.

24 4

24 2

24 2

28 2

30 29 18 465

27 613

27 329

27 286

28 65

27 18

25 2

Mahabaleshwar

T. P.

19 5

20 4

23 5

25 25

24 19 18 18 27 440 2546 1764

18 686

20 154

20 47

19 5

Pune

T. P.

21 3

23 1

26 2

29 14

30 28 27 107

25 169

25 97

25 130

26 76

23 31

21 4

Nagpur

T. P.

22 11

24 23

28 17

33 16

35 32 21 222

28 376

27 286

28 185

27 55

23 20

21 10

Banglore

T. P.

22 9

23 7

26 11

27 27 45 107

25 71

23 111

23 137

23 164

23 53

19 61

20 13

Chennai

T. P.

25 4

26 13

28 13

31 18

33 45

31 87

31 113

30. 119

28 306

26 350

25 135

Thiruvana- T. nthapurarn P.

27 23

27 21

28 39

29 29 27 106 208 356

26 223

26 146

27 138

27 273

27 206

27 75

GEOGRAPHY

33 38

25

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Climate of India

The Physical setting of India

Fig. 17.1 Onset of Southwest Monsoon

26

GEOGRAPHY

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Climate of India

The Physical setting of India

Fig. 17.2 : INDIA : Withdrawl of Southwest Monsoon GEOGRAPHY

27

MODULE - 6 The Physical setting of India

Climate of India 17.2 FACTORS INFLUENCING THE CLIMATE OF INDIA The factors influencing the climate of India are given below: (i) Location and Latitudinal Extent

Notes

India lies roughly between 6°N to 37°N latitudes. The Tropic of Cancer passes through the middle of the country. The southern parts being closer to the Equator, experience high temperatures throughout the year. The northern parts on the other hand lie in the warm temperate zone. Hence they experience low temperatures particularly, in winter. Water bodies surrounding peninsular India make climatic conditions mild along the coastal areas. (ii) Distance from the Sea Southern or peninsular India is surrounded by the Arabian Sea, the Indian ocean and the Bay of Bengal, hence the climate of coastal regions of India is equable or maritime. Contrary to this, the climate of the regions located in the interior of the country are cut off from the oceanic influence. As a result, they have an extreme or continental type of climate. (iii) The Northern Mountain Ranges The Himalayan and adjoining mountain ranges which extend from Kashmir in the Northwest to Arunachal Pradesh in the Northeast, separate India from the rest of Asia. These ranges protect India from the bitterly cold and dry winds of Central Asia during winter. Further more, they act as an effective physical barrier for the rain bearing southwest monsoons winds to cross the northern frontiers of India. Thus, these ranges act as a climatic divide between Indian Sub-Continent and Central Asia. (iv) Physiography The physical features influence the air temperature, atmospheric pressure, direction of winds and the amount of rainfall in different parts of the country. Study the map showing physical features given in the earlier lesson and find out yourself, the relationship between the relief, temperatures, direction of winds and amount of rainfall with the help of climatic maps given in this lesson. This will help you to understand why western ,coastal plains receive more rainfall than the interior parts of Karnataka and Tamil Nadu lying east side of the Western Ghats. You will also understand why Bay of Bengal branch of Southwest monsoon is bifurcated into two parts - one moving along the Ganga Valley to the west and the other along the Brahmaputra Valley to the east. Locate on your Atlas the funnel-shaped Cherrapunji Valley and Mausimram nearby along the steep southern edge of the Meghalaya Plateau. This would give you a clue why Mausimram happens to be the rainiest spot in the world.

28

GEOGRAPHY

Climate of India (v) Monsoon Winds The complete reversal in the direction of winds over India brings about a sudden change in seasons - the harsh summer season suddenly giving way to the eagerly awaited monsoon or rainy season. These winds which change their direction completely are called monsoon winds. The word ‘monsoon’ is derived from the Arabic word ‘Mousim’ which means ‘season’. These winds have such a far reaching influence on India’s climate that it is termed as ‘monsoon type of climate’. The nature of these winds can be described with reference to the surface distribution of pressure in different regions of India during winter and summer seasons. (a)

The Northeast Monsoon and its Effect: During winter, the weather conditions is influenced by high pressure developed over Northwestern part of the subcontinent. This results in the blowing of cold dry winds from this regions towards southern low pressure areas lying over water bodies surrounding peninsular India. Since these winds are cold and dry, they do not cause rainfall and weather conditions under their influence remain cold and dry. However; wherever these Northeast monsoon winds collect moisture while passing over the Bay of Bengal, they bring rain along Coromandel coast. Strictly speaking these winds are planetary winds known as Northeast Trades. In India they are essentially land bearing winds.

(b)

The Southwest Monsoon and its Effect : During summer, the northwestern parts of India become very hot due to very high temperature. This is ascribed to the apparent shift of the sun in northern hemisphere. This results in the reversal of air pressure conditions not only in northwestern India but also on water bodies surrounding the peninsular. As a result, Northeast Trade winds are replaced by Southwest monsoon winds. Since these winds are sea bearing and blow over warm water bodies before reaching land, they are moisture laden, causing wide spread rain over the most parts of India. This period of southwest monsoon from June to September, is known as the rainy season for most parts of the country.

MODULE - 6 The Physical setting of India

Notes

(vi) Upper Air Circulation The changes in the upper air circulation over Indian landmass is yet another cause for sudden outbreak of monsoons in India. Jet streams in the upper air system influence the climate of India in the following ways: (a)

Westerly Jet stream and its Impact: During Winter, at about 8 km. above sea level, a westerly jet stream blows at a very high speed over the subtropical zone. This jet stream is bifurcated by the Himalayan ranges. The northern branch of this jet stream blows along the northern edge of this barrier. The southern branch blows eastwards south of the Himalayan ranges along 25° N latitude. It is believed by meteorologists that this branch of jet stream exercises a significant influence on the winter weather conditions over India. This jet stream is responsible for bringing western disturbances from the Mediterranean region into Indian sub-continent. Winter rain and

GEOGRAPHY

29

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Climate of India

The Physical setting of India

hail storms in northwestern plains and occasional heavy snowfall in hilly regions are caused by these disturbances. These are generally followed by cold waves in whole of northern plains. (b)

Notes

Easterly Jet and its Influence: During summer, due to the apparent shift of the sun in northern hemisphere, the reversal in upper air circulation takes place. The westerly stream is replaced by easterly jet stream which owes its origin to the heating of the Tibetan plateau. This leads to the development of an easterly cold jet stream centered around 15°N latitude and blowing over peninsular India. This helps in the sudden onset of monsoons.

(vii) Western Disturbances and Tropical Cyclones The inflow of western disturbances moves under the influence of westerly jet streams from the Mediterranean Sea. It influences winter weather conditions over most parts of Northern Plains and Western Himalayan region. It brings little rain in winter months. This rain is considered to be very good for wheat crops in northern plains. The tropical cyclones also develop in the Bay of Bengal. The frequency and direction of these cyclones influence weather conditions along the eastern coast during October, November and December. (viii) El - Nino Effect Weather conditions in India are also influenced by EI-Nino which causes wide spread floods and droughts in tropical regions of the world. El-Nino is a narrow warm current which sometimes appears off the coast of Peru in South America. It is a temporary replacement of the cold Peru current which normally flows along this coast. Sometimes, becoming more intense, it increases the surface water temperatures of the sea by 10° C. This warming of tropical Pacific waters affects the global pattern of pressure and wind systems including the monsoon winds in the Indian Ocean. It is believed that the severest drought of 1987 over India was caused by EI-Nino. (ix) Southern Oscillation and its Effect The southern oscillation is a pattern of meteorological changes which are often observed between Indian and Pacific oceans. It has been noticed that whenever the surface level pressure is high over Indian ocean, it is low over Pacific Ocean and vice-versa. When the pressure is high over the Pacific Ocean and low over Indian Ocean, the Southwest monsoons’ in India tend to be weaker. In the reverse case, the monsoons are most likely to be stronger.  The factors affecting the climate of India are: location and latitudinal ex-

tent, distance from the sea, the northern mountain ranges, physiography, monsoon winds, upper air circulation, western disturbances and tropical cyclones, formation of El-Nino and southern oscillation. 30

GEOGRAPHY

Climate of India

MODULE - 6 The Physical setting of India

INTEXT QUESTIONS 17.2 1.

Name the mountain range which acts as a climatic divide for the entire Indian subcontinent _______________________________________________________

2.

Notes

Why is the climate of Mumbai equable and than of Delhi? _______________________________________________________

3.

Name the Jet Stream which brings Western disturbances in India. _______________________________________________________

4.

Why do Northeast Monsoons cause no rainfall in most parts of India ? _______________________________________________________

5.

Why does reversal of winds take place in India before the onset of southwest monsoons? _______________________________________________________

17.3 THE CONCEPT AND MECHANISM OF MONSOON Monsoons refer to a system of winds in the tropical regions under which the direction of winds is reversed completely between the summer and the winter seasons. Under this system, the winds blow from land to sea in winter and from sea to land in summer. Therefore, most of the rainfall in the regions influenced by the monsoons is received in the summer season while winter season is generally dry.  Monsoon implies the system of tropical winds with complete reversal in

their direction between winter and summer seasons. According to the traditional belief, the monsoon is caused by the differential heating of land and sea. Due to a higher temperature over the land in summer, a low pressure area develops over the continents and the winds blow from neighbouring oceans towards the land. These winds are of maritime origin and hence cause ample rainfall in summer. On the other hand, the continents become colder than the neighboring oceans in winter. As a result a high pressure area is developed over the continents. Therefore, winds blow from land to sea in winter. These winds, being of continental origin, are dry and do not cause rain. This traditional theory of monsoon has been criticized by the German meteorologist Flohn. He argues that the differential heating of land and sea is not enough to cause a seasonal reversal of winds at a global scale. He has explained the origin of the monsoon on the basis of seasonal shift of the pressure and wind belts under the influence of the shift of the vertical rays of the sun.

GEOGRAPHY

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MODULE - 6 The Physical setting of India

Notes

Climate of India According to this theory, as the vertical rays of the sun shift northwards over the Tropic of Cancer in summer season, the Inter-Tropical Convergence Zone(ITCZ) also shifts to north. This results in the formation of a low pressure area over the northwestern parts of India. This low pressure is further intensified by the high temperatures in this region. This low pressure area sucks the air from the Indian Ocean towards the Indian landmass in the form of Southwest monsoons. In winter season, the ITCZ shifts southwards and a mild high pressure is produced over northern parts of India. This high pressure is further intensified by the equator ward shift of the sub tropical high pressure belt. Due to high pressure over northern lndia, the winds start blowing from northeast as retreating monsoons. According to recent observations, the origin of Indian monsoon is influenced by a number of other factors, besides the differential heating of land and sea and the seasonal shifts of pressure and wind belts. One of the most important factors among these is the system of subtropical westerly and tropical easterly jet streams. The subtropical westerly jet streams blowing over India in winter cause a high pressure over northern India. It thus intensifies the northeast monsoons. This jet stream shifts northwards beyond India in summer season and tropical easterly jets develop over India in this season. The behaviour of this jet streams is partly responsible for the variations in the time of onset of southwest monsoons over India.  According to the traditional belief, monsoon is caused by the differential heating and cooling of land and sea.  Flohn, a German meteorologist opined that monsoon originates due to the shifting of planetary pressure and wind belts,  According to modern scientists, the origin of Indian monsoon is influenced by a number of factors, important among them is the system of jet streams.

INTEXT QUESTIONS 17.3 1.

Define monsoons. _______________________________________________________

2.

What is the main cause of the origin of monsoons according to Flohn? _______________________________________________________

3.

List three important theories explaining the origin of monsoon in India. (i)

___________________________________________________

(ii)

___________________________________________________

(iii) ___________________________________________________

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GEOGRAPHY

Climate of India 17.4 CYCLE OF SEASONS IN INDIA By now, you have understood that the complete reversal of direction of winds is the most striking feature of the monsoons. These changing monsoon winds result in the change of seasons over the year. It is, therefore, important to understand in detail, the prevailing weather conditions throughout India during different seasons.

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Notes

Climatically, the year is divided into following four seasons in India: (i)

The cold weather season - December to February;

(ii)

The hot weather season - March to may in south and upto June in the north;

(iii)

The advancing southwest monsoon season - June to September;

(iv)

The retreating southwest monsoons season - October and November.

(i) The Cold Weather Season This season usually begins with late-November in northern India. January is the coldest month over most parts of the country as sun shines vertically over the Tropic of Capricorn in the southern hemisphere. During these months, the mean daily temperatures remain below 21°C over northern plains and northern mountain regions. The night temperatures sometimes fall below freezing point resulting in wide spread damage to the standing crops due to frost. The temperature increases as one moves from north to south (Fig. 17.3). As a result of low temperatures, a feeble high pressure area develops over northern parts of India (Fig17.4) This mild high pressure causes the off-shore Northeast monsoon winds. Their direction in Northern Plains is westerly owing to the relief. These land bearing winds being cold and dry don’t give rain over most parts of the country. However, these winds cause rain along the Coromandel coast since they collect moisture on their way over the Bay of Bengal. The succession of depressions is another feature of this season. These low pressure systems are called “Western disturbances” as they originate in the Mediterranean region. These depressions move with the westerly jet streams. Covering a long distance over Iraq, Iran and Pakistan, they reach India around mid December. Their arrival results in the increase of temperature and in light rains over northern plains. They cause wide spread snowfall over western Himalayas and the adjoining ranges. At times hailstorms cause widespread damage to the standing rabi crops in northwestern plains. The meager rainfall caused by these disturbances is of great importance to the standing crops, particularly the wheat, in unirrigated areas. These depressions are followed by cold waves which bring down temperatures considerably. The peninsular India has no well defined winter season. The mean monthly temperatures in the month of January is above 20°C in this part. Moreover, the coastal plains hardly experience any seasonal change as is clear from the mean monthly

GEOGRAPHY

33

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Fig. 17.3 INDIA : Temperature (cold weather season)

34

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Climate of India

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GEOGRAPHY

35

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India - Physical Features

The physical setting of India

Fig. 17.4 INDIA : Pressure and wind direction

36

GEOGRAPHY

temperature of above 27°C at Thiruvananthapuram. But Chennai records a temperature of 25°C during December and early January owing to the rains caused by Northeast monsoon winds (Table 17.1) The important characteristics of cold weather season are:  Low temperatures in the north and their gradual increase towards southern parts of India.  Blowing of cold and dry northeast monsoon resulting in dry weather conditions in most parts. Coromandel coast receives rainfall during winter.  Western disturbances cause light rain in northern plains and snowfall over the Himalayan ranges. (ii) The Hot Weather Season The apparent movement of the sun towards the north increases the temperatures in the northern plains. As a result, the spring sets in soon giving way to the hot weather season which lasts till end of June in this region. The temperatures increase northwards and reach around 45°C in mid May in most parts of the northern plains. The characteristic features of this season are afternoon dust storms and ‘Loo’ which is a hot dry wind which blows during May and June mainly over the northern plains. These winds cause heat stroke resulting in deaths of hundreds of people every year. The day temperatures at times rise above 45°C in some northwestern parts of the country. The wind direction is variable during this season. The weather conditions are generally hot and dry throughout the country. However, dust storms cause drizzle in Northern Plains. Light showers are also experienced in Kerala, West Bengal and Assam. In Kerala, these premonsoon showers are popularly known as “Mango Showers”. In West Bengal and Assam, they are called Northwesters or Kal Baisakhi. Sometimes, due to high velocity of winds these Northwesters cause heavy loss of life and property. 

The main characteristic features of hot weather season are hot and dry weather, blowing of Loo - a hot dry wind in northern plains, afternoon dust storms, sometimes causing drizzle and mild showers in Kerala (Mango showers), West Bengal and Assam (Northwesters / Kal Baisakhi).

(iii) The Advancing Southwest Monsoon Season It is a rainy season for most parts of India. It starts with the inflow of Southwest monsoons which strike the coast of Kerala normally in the first week of June and cover most of India by mid July. This weather continues till September. The arrival of these warm moisture laden winds brings a total change in weather conditions. Their arrival causes sudden rains which bring down the temperatures considerably. The decline in temperature is between 5°C to 10°C. The sudden onset of

rain is called break of monsoons or the burst of monsoons. The arrival of these winds may be delayed by a week or two depending upon the pressure conditions over northern plains and over the Indian ocean (Fig.17.1) The peninsular shape of India divides these Southwest monsoons into two branches - Arabian Sea branch and Bay of Bengal branch. (a)

Arabian Sea branch of Southwest monsoons strikes the western coast of India and causes heavy rains on the western slopes of the Western Ghats. After crossing the Western Ghats, these winds cause less rainfall on the eastern slopes as they gain temperature while descending. This area is, therefore, known as rain shadow zone. This explains why interior parts of Maharashtra, Karnataka and Telangana get meagre rains from these winds. Southwest monsoons striking along the coast of Saurastra and Kuchchh and pass over Rajasthan and beyond to meet the Bay of Bengal branch. These winds cause widespread rain in these states and western Himalayan region.

(b)

The Bay of Bengal branch is divided into two sub branches after striking eastern Himalayas. One branch moves towards the east northeast direction and causes heavy rains in Brahmaputra valley and northeast hills of India. The other branch moves towards northwest along the Ganga valley and the Himalayan ranges causing heavy and widespread rains over vast areas. In this region, the amount of rainfall decreases from east to west owing to the progressive decrease in humidity of these winds(Fig. 17.8).

(c)

The characteristics of Southwest Monsoons (i)

These winds generally strike the Indian coast in the first week of June. but their arrival and departure may be before time or even it may be delayed.

(ii)

There may be dry spells in between rainy periods. Such long dry spells may even lead to failure of crops.

(iii) At times, these winds skip over certain regions without any cause. (iv) The amount and timing of rainfall and intervening duration of wet and dry spells varies from year to year. This is known as the vagaries of the monsoons. (v)

The spatial distribution of rainfall is uneven - some regions may receive heavy rains while the others will have to be contented with meagre or scanty rains.

(vi) Generally, these winds start retreating by the end of September. But, sometimes, their departure may be delayed till October or they may retreat even much earlier.

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The Physical setting of India

Fig. 17.6 INDIA : Temperature (during hot season) GEOGRAPHY

39

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Climate of India

The Physical setting of India

Fig. 17.7 INDIA : Pressure and winds (during southwest monsoon)

40

GEOGRAPHY

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The Physical setting of India

Fig. 17.8 INDIA : Rainfall GEOGRAPHY

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The Physical setting of India

The main features of advancing Southwest monsoon season are:  

Notes  

Low pressure conditions over northwestern parts of India and high pressure conditions over seas. The general wind direction particularly on the Arabian Sea and the Bay of Bengal is southwest to northeast. They cause wide spread rain interspersed with dry spells. The onset of monsoons is in the first week of June and withdrawal by the end of September. The weather is generally hot and humid during this season.

(iv) The Retreating Southwest Monsoon Season The Southwest monsoons start retreating in the first week of September from Pakistan border in Northwest India. Thus, these winds withdraw earlier from the regions where they reach the last. The retreat of these winds takes place due to weakening of low pressure area over the northwestern parts. This happens due to low temperatures caused by apparent shift of the sun towards the equator and also owing to the widespread rains bringing down temperatures perceptibly. Consequently, the air pressure starts decreasing. Such changes in the patterns of atmospheric pressure causes Southwest monsoons to withdraw. Hence, this period is known as the season of retreating Southwest monsoons. By the end of October, these winds retreat from most of northern India. As a result, fair weather conditions prevail over this region. The low pressure area lying over Northwest India is transferred to the middle of the Bay of Bengal by the end of October. As a result of these unstable conditions, severe cyclonic storms originate in the Bay of Bengal. These cyclonic storms strike along the eastern coast of India causing wide spread rain in the coastal regions. Some times very sever storms cause damage to the standing crops, cattle, property, the lines of transports, communication and even electricity. Tamil Nadu coast receives maximum of its rainfall during October and November - the period of retreating monsoons. The main characteristic features of retreating Southwest monsoon season are:    

weakening of low pressure area over Northwest India; fall in temperatures throughout India; shifting of low pressure area to the south; and origin of cyclonic storms in the Bay of Bengal causing heavy rains and damage to crops and property along the eastern coast of India.

INTEXT QUESTIONS 17.4 1. 42

List four important features of each seasons given below (a)

Cold Weather Season

GEOGRAPHY

Climate of India (i) ______________________ (ii) ________________________

MODULE - 6 The Physical setting of India

(iii) _____________________ (iv) ________________________ (b) Hot Weather Season (i) ______________________ (ii) ________________________ (iii) _____________________ (iv) ________________________ (c)

Notes

The Advancing Southwest Monsoon Season (i) ______________________ (ii) ________________________ (iii) _____________________ (iv) ________________________

(d) The Retreating Southwest Monsoon Season (i) ______________________ (ii) ________________________ (iii) _____________________ (iv) ________________________

17.5 DISTRIBUTION OF ANNUAL RAINFALL Study the map carefully. You will find that the regional variations in average annual rainfall are well pronounced. The distribution map of rainfall shows that northeastern parts of Jammu and Kashmir and extreme western Rajasthan receive a rainfall of less than 20 cm. On the other hand, the west coastal plains, Sub-Himalayan areas of northeast India including the Shillong plateau receive more than 200 cm. of annual rainfall. Southern slopes of Khasi and Jayantia Hills, particularly the Cherrapunji valley receive the highest rainfall exceeding 1000 cm. Starting from the southern coast of Gujarat, the isohyte of 200 cm. runs somewhat parallel to the coast of Western Ghats upto kanyakumari. To the east of Western Ghats, the rainfall drops abruptly below 60 cm. over interior Maharashtra and Karnataka. Most parts of Punjab, Haryana, central and eastern Rajasthan and western Gujarat also receive rainfall below 60 cm. Starting from the southwestern parts of Jammu and Kashmir, the isohyte of 100 cm. moves eastwards upto east of Allahabad from where it bends to the west and south west, running over western Madhya Pradesh, eastern Maharashtra and northern Andhra Pradesh, it joins eastern coast near Visakhapattnam. To the west and south west of this isohyte, the areas receive less rainfall. Some parts of Coromondel coast receive a rainfall of more than 100 cm. The areas receiving less than 100 cm. of rainfall depend on means of irrigation for agricultural activities In India, distribution of rainfall particularly of the southwest monsoon has a close relationship with the relief. Hence it is even described as “relief” or “orographic” rainfall. By and large places with higher altitude have greater chance to catch more rainfall than the places with less altitude. The direction of moist winds also matters.

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43

MODULE - 6 The Physical setting of India

Climate of India The distribution of annual rainfall in different parts of India shows the following trends: 

The rainfall decreases as one moves from Kolkata to Amritsar.



It shows declining trend towards interior from the coastal areas on Deccan Plateau.



Northeastern parts receive more rainfall than north western parts of India.



Areas lying on the windward side receive more rains than the areas lying on the leeward side.

Notes

17.6 THE MONSOONAL UNITY IN INDIA Despite the regional diversities in climatic conditions, it is obvious from the above description that there exists a climatic unity in India. The ‘Climatic Unity’ means that weather conditions over different parts of India are more or less the same during different seasons round the year leaving minor variations as exceptions to the rule. Indian climate is called ‘monsoon climate’. It explains how much influence the monsoon winds have in bringing climatic unity. This unity in climatic conditions results from the combined influence of regular movements of monsoons (seasonal winds) and the bounding role of the Himalayan mountain system. The monsoonal unity of India caused by these twin factors is discernible. It reflects upon the life styles and activities of the common masses in India. They are: (i)

Rhythm of seasons: The sequence of hot, wet and cold seasons affects the life styles and economic activities of the people throughout India in the following ways: Firstly, the farmers all over India start their agricultural activities like ploughing of fields, sowing of seeds, transplantation etc. with or just before the onset of monsoons. Kharif crops - rice and millets, cotton and sugarcane in different areas is an expression of amount of rainfall they receive. During winter, wheat is the major rabi crop in cool and irrigated areas; whereas barley, gram and oil seeds are common crops of unirrigated areas in northern and central India. Secondly, the clothes are also affected by seasons. During summer, the people wear cotton clothes whereas the woollen clothes are used in winter season especially in north and central India. Thirdly, most parts of lndia have to bear a long dry season; contrary to it, the season of life giving rains is limited to only a few months. This has a far reaching effect on the life style of the Indian people. When the rain drops the monsoon clouds fall on the thirsty parched land. Their music and fragrance coming out of the land generate similar emotional responses all over India. This is reflected in the Kajari of Bhojpuri and Malhar of Brij and their counter parts in other regions of India. Most of the Indian festivals are closely

44

GEOGRAPHY

Climate of India linked with seasons. In north India, Baisakhi is celebrated when rabi crop is ready for harvesting. During winter, when the sun shines vertically over the Tropic of Capricorn and extreme cold weather conditions prevail over northern plains Lohri and Makar Sakranti are celebrated in the north and west while Pongal distinctly is its southern counterpart. Holi is celebrated in spring after bidding good bye to the prolonged cold winter especially in the north.

MODULE - 6 The Physical setting of India

Notes

Fourthly, the rainfed subsistence farming has been the oldest response of the village community. Its entire economy is based on it, howsoever meagre rain it may be. Lastly, the seasonal and regional variations in weather conditions have made different regions capable of producing different crops in varying quantities making all regions completely interdependent. This is not a less contribution of the monsoons in promoting underlying unity despite all pervasive diversity. (ii)

Thirst for Water: You know that rain occurs over most parts of India only during four or five months of the year. Thus, India remains dry for seven to eight months in a year. Even during rainy season, spells of dry period are common. Being an agricultural society, the need for water is all pervasive in most parts of India. Even the rainiest parts around Cherrapunji and in Konkan and Kerala have no drinking water during the long and dry summer months. All eyes are focussed on black monsoon clouds in every part of the country.

(iii) The Waiting for Monsoon Rains: The farmers as well as citizens all over India eagerly wait for monsoon rains after a long dry season not only to get rid of summer heat but to start agricultural activities which sustain rural as well as urban economy. So, bursting of monsoon is welcomed with equal joy everywhere in India. (iv) Incidence of Droughts and Floods: The paradox of Indian monsoons is that no part in India is spared from occasional or even frequent floods or droughts, if not famines. The drought are common even in the areas of heavy rainfall like Kerala and Assam; likewise, dry areas of Northwest India are not free from floods, be it Punjab or Rajasthan. Consequently, there is need to conserve, control and store water for irrigation, drinking and power generation.

INTEXT QUESTIONS 17.5 1.

Write True or False against each of the following statements (a)

The amount of rainfall decreases from east to west in northern plains.

(b) Gujarat and Rajasthan receive low rainfall as monsoon winds become dry on reaching these states. GEOGRAPHY

45

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Notes

Fig. 17.9 INDIA : Average Annual Rainfall

46

GEOGRAPHY

Climate of India (c)

The date of arrival of monsoon winds is always definite in different parts of India.

MODULE - 6 The Physical setting of India

(d) Coromandel coast receives bulk of its rainfall in October-November from Northeast monsoon winds. (e) 2.

Only certain parts of India experience the occurrence of droughts and floods.

Notes

Name two areas of India which receive less than 20 cm of annual rainfall. (i)___________________________ (ii)_______________________

WHAT YOU HAVE LEARNT India is a country of climatic diversities which are expressed in the variations in the distribution of temperature, pressure, winds and amount of precipitation. The factors which are responsible for determining the climate of different regions of India include her location and latitudinal extent, physiography, the role of Himalayan ranges as a climatic divide, the monsoon winds, upper air circulation, western disturbances and cyclonic storms. Derived from Arabic word ‘mousim’, monsoon implies the rhythm of season and seasonal reversal of winds. Meteorologically, the year in India is divided into four seasons namely the cold weather season, the hot weather season, the advancing southwest monsoon season and the retreating southwest monsoon season. These seasons have different characteristics of weather conditions.

TERMINAL QUESTIONS 1.

How do western disturbances influence the weather conditions of north west India?

2.

Distinguish between: (i)

The cold weather season and hot weather season;

(ii) The southwest and northeast monsoons. 3.

Give reasons : (i)

Dras in Kargil is always colder than Thiruvananthapuram.

(ii) Winter is dry and cold over greater parts of India. (iii) Southwest monsoons start retreating from northern India after September. (iv) The western coastal plains receive more rainfall compared to the interior plateau region lying east of the Western Ghats. GEOGRAPHY

47

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Notes

Climate of India 4.

Describe five major factors which influence the climate of India. Illustrate your answer with examples.

5.

Explain with suitable examples the uneven distribution of rainfall in India.

6.

Identify the characteristics of monsoons in India.

7.

Locate and label the following on the outline maps of India (i)

Dras and Cherrapunji;

(ii) Areas receiving rainfall from ‘western disturbances’; (iii) Areas receiving rainfall from northeast monsoons. (iv) Areas receiving annual rainfall less than 20 cm.

ANSWER TO INTEXT QUESTIONS 17.1 1.

(a) Jaisalmer in Rajasthan desert (b) Dras in Jammu & Kashmir

2.

(i)

Thiruvananthapuram

(ii) Delhi (iii) (a) Thiruvananthapuram (b) Nagpur (c) Delhi (d) Chennai (iv) June, July, August, September (v) Leh. 17.2 1.

The Himalayas

2.

Mumbai lies along the western coast while Delhi is too far away to have any oceanic influence.

3.

Westerly jet stream.

4.

Because they are cold and dry land bearing winds.

5.

Owing to the reversal of air pressure conditions between land and sea at the peak of the summer season.

17.3 1. 48

Monsoon refer to a system of winds in the tropical regions under which the GEOGRAPHY

Climate of India direction of winds is reversed completely between summer and winter. 2.

The shifting of planetary pressure and wind belts. .

3.

(i)

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Differential heating and cooling of land and sea.

(ii) Shifting of planetary pressure and wind belts.

Notes

(iii) System of jet streams. 17.4 1.

(a) (i)

cold and dry in most parts of India.

(ii) direction of winds is generally northeasterly. (iii) light rain, hails in northwestern plains and snowfall in Western Himalayan region. (iv) rainfall along Coromondal coast from N.E. monsoons. (b) (i)

generally hot and dry throughout India.

(ii) variable wind direction. (iii) blowing of hot and dry wind called “Loo” in northern plains causing heat strokes. (iv) light rain in Kerala, W. Bengal and Assam. (premonsoon showers) (c) (i)

generally rainy throughout India.

(ii) general direction of winds is southwesterly. (iii) onset and withdrawal of these winds is somewhat certain with marginal variations. (iv) amount of rainfall varies from place to place and time to time. (d) (i)

Weakening of low pressure are over northern parts of India.

(ii) fall in temperatures throughout India. (iii) shifting of low pressure areas to the Indian ocean. (iv) origin of cyclonic storms in the Bay of Bengal causing heavy rains on coastal areas. GEOGRAPHY

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Climate of India 17.5 1.

(a) True; (b) False; (c) False; (d) True; (e) False

2.

(a) Ladakh (b) Rajasthan desert

Notes HINTS TO TERMINAL QUESTIONS 1.

Refer to 17.2 (vii)

2.

(i)

Refer to 17.4 (i) and (ii)

(ii) Refer to 17.4 (iii) and (iv) 3.

(i)

Because Dras is located in high altitude and latitude in interior parts of Jammu and Kashmir while Thiruvananthapuram has coastal location and is nearer to equator.

(ii) Refer to 17.4 (i) (iii) Refer to 17.5

50

4.

Refer to 17.2

5.

Refer to 17.5

6.

Refer to 17.6

7.

Refer to maps.

GEOGRAPHY

Natural Disasters

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18 Notes

NATURAL DISASTERS

Humans have been coping with natural disasters since time immemorial. There are so many disaster which can not be controlled by human intervention. They are destined to bring their tragic consequences of human destruction. Due to human intervention in the natural processes, the destructive power and frequency of natural disasters have increased considerably. According to U N statistics, natural disasters kill 1,00,000 persons on an average and cause property damage of Rs 20,000 crores world wide per year. Among the top ten natural disaster-prone countries, India stands second after China.Therefore, there is a need for creating awareness among all sections of the people about it’s causes, consequences as well as preventive measures so that they can handle as an individual, and as a members of society. In this chapter we will study five natural disasters i.e. earthquakes, land slides, droughts, floods and cyclones.

OBJECTIVES After studying this lesson you will be able to: 

explain the meaning of the words natural ‘Hazard’ and ‘Disaster’.



differentiate between hazard and disaster



recognize and describe some disaster-prone areas from each physical division of India.



describe some adverse effects of natural disasters.



give example of some other nuturological disasters.



suggest measures to mitigate or reduce the problems and sufferings arising before, during or after the disaster.

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18.1 DISASTERS IN INDIA – A BACKGROUND

Notes

India is struggling with disasters from many years. How can we forget the day when killer waves (tsunami) struck the coastal parts of India on 26th December 2004 or the morning of 26th January 2001, when western part of India was badly affected by earthquake. These are just few examples. We always listen such kind of news in print or electronic media that one part of India is affected by flood where as another faces drought. Due to vulnerability of different kinds of disasters, it is said that India is a disaster prone country, the reasons are: 1.

Over 55% of the land area is vulnerable to earthquakes,

2.

12% is flood prone,

3.

8% is vulnerable to cyclones and

4.

70% of the land under cultivation is drought prone.

18.2 NATURAL HAZARDS AND DISASTERS The vulnerability of enviornment has been increasing continuously due to human activities. But this is not one sided relationship. Humans are also the components of the enviornment. Hence they can’t escape from the effects of environmental change processes. When local, regional or global processes of environment pose danger to humans or their property, they are simply natural events. For example, the blizzard blowing in the Antarctica is a natural event. But if this blizzard porses dangers to our lives and property, then it becomes a disaster. For instance, tsunami was caused by an earthquake that occurred in the sea near Sumatra (Indonesia) on 26 December, 2004. It turned into a disaster for India, Srilanka and some other countries of Southeast Asia. It caused wide spread loss to human life and property in Andaman and Nicobar Islands and on the coasts of Andhra Pradesh and Tamil Nadu. Table 18.1: Difference between Natural Hazard and Disaster Hazard

52

Disaster

1.

A hazards is a dangerous physical condition or event.

1. A disaster disrupts the normal function of the society caused by a hazard.

2.

Earthquakes, floods, volcanic erruption, land slides, droughts etc are called natural hazards before they cause loss of life and damage to property.

2. It causes damage to property and loss of life but it disrupts the opportunities of employment also.

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Natural Disasters

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3.

Small number of people are affected.

3. A large number of people are affected by it.

4.

It may cause injury, loss of life or damage of property.

4. It causes wide spread loss to life and property.

5.

Earthquakes, floods, volcanoes, tsunami, land slide, drought etc. are natural hazards.

5. It affects the society to such an extent that external aid becomes, necessary to compensate the losses.

Notes

 Nearly 6 crore people are effected by natural disasters every year.  Natural events, when pose danger to humans, are called hazards.

INTEXT QUESTIONS 18.1 1.

When do natural events become natural hazards? ________________________________________________________ ________________________________________________________

2.

What is a tsunami? ________________________________________________________ ________________________________________________________

18.3 FLOODS With the arrival of Monsoon, people living in 4 crore hectares area of the country become extremely nervous. No one knows when there will be a flood in the river and their hard earned belongings will be washed away. In comparison to other disasters flood cause more damage to life and property. Twenty percent of deaths caused by floods in the world, occur in India. What is a flood The inundation of an area by water is called a flood. In other words, when a river over flows its banks and water spreads in the surrounding areas is a flood. Various causes of flood, losses by flood and flood control measures are described below: Cause of flood The causes of flood in India are as follows: GEOGRAPHY

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(i) Heavy rainfall : Heavy rain in the catchment area of a river causes water to over flow its banks, which results in the flooding of nearby areas.

Notes

(ii) Sediment deposition : River beds become shallow due to sedimentation. The water carrying capacity of such river is reduced. As a result the heavy rain water over flows the river banks. (iii) Deforestation : Vegetation hampers the flow of water and forces it to percolate in the ground. As a result of deforestation, the land becomes obstruction free and water flows with greater speed into the rivers and causes flood. (iv) Cyclone : Cyclone generated seawaves of abnormal height spreads the water in the adjoining coastal areas. In October 1994 Orissa cyclone generated severe floods and caused unprecedented loss of life and property. (v) Interference in drainage system: Drainage congestion caused by badly planned construction of bridges, roads, railway tracks, canals etc. hampers the flow of water and the result is flood. (vi) Change in the course of the river: Meanders and change in the course of the river cause floods. (vii) Tsunami : Large coastal areas are flooded by rising sea water, when a tsunami strikes the coast. Losses by flood : Humans and animals both are affected by flood. People are rendered homeless. Houses are damaged or collapse. Industries are crippled. Crops are submerged in flood water. Domestic as well as wild animals die. Boats and fishing nets etc. are lost or damaged in coastal areas. Out break of epidemics like malaria and diarrhoea etc. are common after flood. Potable water is contaminated and sometimes becomes scarce. Food grains are lost or spoiled, their supplies from outside become difficult. Losses by annual floods, instead of decreasing are increasing every year. In 1953 2.43 crores of people were affected. By 1987 the number of flood affected people rose to 4.83 crore. According to an estimate on an-average property worth Rs. 210 crores is lost in floods every year. Flood affects about 6 crore people and crops of one crore hectare are damaged. Flood prone areas : About 4 crore hectare area of our country is flood-prone, which is one eighth of the total area. The most flood prone areas are the Brahmputra, Ganga and Indus basins. As far as states are concerned, Uttar Pradesh, Bihar, West Bengal and Orissa are the most flood affected states followed by Haryana, Punjab and Andhra Pradesh. Now a days Rajasthan and Gujarat also feel the fury of floods. Karnataka and Maharashtra are no-longer immune to floods.

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Notes

Fig. 18.1 INDIA : Flood Prone Areas

Flood control measures (i) Reservoirs : By constructing reservoirs in the courses of rivers could stores extra water at the time of flood. Such measures adopted till now however, have not been successful. Dams built to control floods of Damodar could not control the flood. (ii) Embankments : By building flood protection embankments, floods water can be controlled from overflowing the banks and spreading in near by areas. GEOGRAPHY

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Notes

Building of embankments on Yamuna, near Delhi, has been successful in controlling the flood. (iii) Afforestation : The furry of flood could be minimized by planting trees in catchment areas of rivers. (iv) Restoration of original drainage system : Drainage system is generally choked by the construction of roads, canals railway tracks etc. Floods could be checked if the original form of drainage system is restored. Flood Management : About 4 crore hectare area is flood prone. Out of this, 1.44 crore hectare areas has been made secure to some extent from the devastation by floods. To achieve this goal, embankments and drainge channels have been constructed. Protection of towns and cities have been adopted. Villages are relocated on comparative by higher ground. By the end of Ninth Plan 8000 crore rupees have been spent on flood management. Some do’s and donts before, during and after the flood (i) Listen to the radio for advance information and advise. (ii) Disconnect all electrical appliances, move all valuable household goods and clothing out of reach of flood water. Adopt such measures only when there is a forecast of flood or you suspect that flood water may reach the house. (iii) Move vehicles, farm animals and moveable goods to the higher ground. (iv) Prevent dangerous pollution. (v) Keep all insecticides, pesticides etc. out of the reach of flood water. (vi) Switch off electricity and gas, in case you have to leave the house. (vii) Lock all door and windows if you have to leave the house. (viii) Do not enter flood water on foot or in a vehicle as far as possible. (ix) Never wander in the flooded area on your own. 

The inundation of an area by rain water is called flood.



The basins of Indus, Ganga and Brahamaputra rivers are the most flood prone areas.

INTEXT QUESTION 18.2 1.

Name any two causes of flood. (i) ____________________________________________________ (ii) ____________________________________________________

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2.

How much area of the country is flood prone? ________________________________________________________

3.

Name any two measures of flood control. (i) ____________________________________________________

Notes

(ii) ____________________________________________________ 18.4 DROUGHT The tragedy caused by drought affects the people slowly and vastly. This is different type of agony but painful. To see domestic animals to die of hunger and thirst before ones own eyes; to send beloved members of the family in search of employment to far off places in extremely uncertain and exploitative conditions, reduction in diet to reduce the already meager diet, to wander in search of work all day long in relief works and return rejected and empty-handed in the night, these are some of the heart rending scenes from the drought affected areas of India. What is a drought ? According to meteorologists the rainfall deficiency during a long period over a large area is called a drought. Some times in Hindi language famine Akal and Anavrishty are also used for drought. Drought can also occur when ground water level is not within reach of agricultural communities. The government also declares on area affected by drought, if more than 50 percent crop loss happens in an area due to meteorological condition. Causes of drought Major cause of drought in India is scarcity of rain. But humans have interfered in the environment processes by their activities. People have filled up the natural resources like ponds and lakes. They have destroyed the vegetation cover. Vegetation cover impedes the flow of rainwater and force it to percolate in the ground. Humans have dug lakhs of tube wells and depleted the ground water reservoirs. Impact of drought : Droughts cause scarcity of food and water. Hungry and thirsty people cry for help. People die of hunger, malnutrition and epidemics. People are forced to migrate from their area of residence. Crops fail due to scarcity of water. Cattle because fodder and water are not easily available. Farmers are deprived of their employment. People leave their villages with their families for a long, unknown and uncertain journey in the pursuit of food, water, green fodder and employment.

GEOGRAPHY

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Drought prone areas of India

Notes

Study the map carefully given below. There is a major reason that lies between South Rajasthan and Tamilnadu. It includes west south Rajasthan and Tamilnadu. It includes areas of west Madhya Pradesh, central Maharashtra, Andhra Pradesh and Karnataka. Due to deficiency in Monsoon rainfall and environmental degradation, Rajasthan and Gujrat are generally affected by drought. Out of 593 districts in India, 193 districts are severely drought prone. In 2003 most parts of Rajasthan experienced drought for the fourth consecutive year.

58

Fig. 18.2 INDIA: Drought Prone Areas

GEOGRAPHY

Measures to cope with Drought (i) Suitable farming methods for arid areas : By adopting the following methods it is possible to mitigate the intensity of drought. The methods are: Production of coarse and hardy cereals; conservation of soil moisture by deep ploughing, storing water behind small dams, collecting water in ponds and tanks and use of sprinklers for irrigation. (ii) Sowing drought resistant crops: By sowing drought resistant crops of cotton, Moong, pearl millet, wheat etc, the impact of drought could be mitigated to a certain extent. (iii) Rain water harvesting : Collection of each and every drop of rain could help in coping with the drought. (iv) By making high bunds around the fields, adoption of terrace cultivation, planting trees on the bunds of fields, the use of rainwater can be maximised. (v) Water can also be conserved by taming the irrigation canals with mortar and bricks. (vi) Small quantity of water can irrigate comparatively larger area by using drip irrigation method. Drought prone area programme This programme was initiated in 1973. The objectives of the programme are as follows: (i) To minimise the adverse impact of drought on crops, domestic animals, productivity of land, water and human resources. This could be done by integrated development by using appropriate technologies as it was done for the natural resources of Gujrat. (ii) By developing, conserving and suitably using the rainwater, the ecological balance could be maintained for a longer period. (iii) To improve the economic and social conditions of the section of society who do not have access to resources and facilities.  

The rainfall deficiency during a long period over a large area is called a drought. States of Rajasthan and Gujrat are comparatively more droughtprone than other states.

INTEXT QUESTIONS 18.3 1. 2.

What is a drought? ________________________________________________________ Fill in the blanks with appropriate words out of these given in the brackets. (i) The most drought prone state of India is _____________ (Assam, Rajasthan, Chhatisgarh) (ii) In drought prone areas the impact of drought can be minimised by adopting _____________ (Flood irrigation, sprinkler irrigation)

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18.5 LANDSLIDES

Notes

A major landslide occurred in the midnight in a place called Lamari on the foot path leading to Kailash Mansarover about 60 km away from Dharchula, in August 1998. Lamari is situated between Bendi and Malpa. The debris of this landslide slipped into river Kali and blocked its flow. The water of the river spread over an area of 1½ square km. Thus a lake was created in which the water was flowing. Some pilgrims going to Kailash Mansarovar were resting here in this fateful night. This landslide killed 60 pilgrims. What is a Landslide The slipping of masses of rocks, earth or debris downwards on the mountain slopes or banks of the rivers is called a landslide. The occurance of landslides in mountainous areas is increasing day by day. The impact of landslides on the people in the mountains is clearly visible.

60 60

Fig. 18.3 India : Major landslide prone areas GEOGRAPHY

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Landslide prone areas : The landslides are a common feature in Himalaya, Western ghats and in river valleys. The state of Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim and all the seven states of North East India, are most vulnerable to landslide. In southern India Mahrastra, Karnataka, Tamil Nadu and Kerala bear the brunt of landslides. Causes of landslides 1.

Heavy rain : Heavy rain is the main cause of landslides.

2.

Deforestation : Deforestation is another major cause of landslides. Tree, brushes and grasses keep the soil particles compact. Mountain slope looses their protective cover by felling of trees. The rain water flows on such slopes with unempeded speed.

3.

Earthquakes and volcanic explosions : Earthquake is a common feature in the Himalaya. Tremors destabilize the mountains and the rocks tumble downwards. Volcanic explosions also trigger landslides in the mountainous areas.

4.

Building of roads: Roads are built in mountainous areas for development. During the process of the construction of road, a large amount of rocks and debris has to be removed. This process dislodges the rock structure and changes the angle of slopes. Consequently landslides are triggered.

5.

Shifting agriculture : In the North Eastern part of India, the number and frequency of landslides has increased due to the practice of shifting agriculture.

6.

Construction of houses and other buildings : For giving shelter to the ever-increasing population and promotion of tourism more and more house and hotels are being built. In building processes large amount of dibrises created. This causes the landslides.

Notes

Impact of landslide (i)

Degrading of environment : Landslides are degrading the environment of mountains. Natural beauty is deminishing slowly and slowly.

(ii) Sources of water are drying up. (iii) Flooding in rivers is incrasing. (iv) Roads are blocked. (v) Life and property are lost Measures to control landslides and to mitigate their impact (i)

Afforestation : Trees and brushes help in binding the soil particles.

(ii)

New technology in road construction : Roads should be constructed in such a way, that lesser amount of debrisses are generated.

(iii) Ban on quarrying of stones and mining of minerals GEOGRAPHY

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(iv) Instead of exploitation of forests, they should be used scientifically. (v)

Permanent crops like orchards of fruits should replace the seasonal or annual Drops.

(vi) By controlling the surface flow of water, seepage of water should be minimised. Notes

(vii) Retaining walls can be built of mountain slopes to stop land from slipping. (viii) Hazard mapping should be done to locate areas commonly prone to landslides. Building and construction activities may be banned in such areas.  

The slipping of masses of rocks, earth or debris downwards on the mountain slopes or banks of rivers is called a landslide. During rainy season landslides are a common feature in Himalaya, Western Ghat and deep river valleys.

INTEXT QUESTIONS 18.4 1.

Name any two causes of landslide. (i) ______________________

2.

Name two most landslide prone areas. (i) ______________________

3.

(ii) ______________________

(ii) ______________________

Choose the correct answers given in the brackets. (i)

Which state of South India is landslide prone? (Andhra Pradesh, Tamil Nadu)

(ii)

Which measure is adopted to controll landslide (Levelling of slope, construction of strong wall on the slope).

18.6 EARTHQUAKE In simple words sudden shaking or trembling of the earthsurface is an earthquake. Most earthquake are a minor tremor. Larger earthquakes usually begin with slight tremors but suddenly they turn into violent shocks and after that the intencity of shocks deminishes. Tremors or shocks are felt for a few seconds only. Earthquake is a hazard that strikes suddenly. A hindi poet described the earthquake in these word. “Earthquakes strikes without pre information but the breathing stops without informing the man.” Earthquake can occur at any time of the year, day or night. Its impact is very sudden. There are no warning signs of earthquakes. Extensive and sincere research has been conducted but success has eluded humans in the forcast or prediction of earthquake. High risk earthquake prone areas: Bureau of Indian Standard has prepared a 62

GEOGRAPHY

Natural Disasters MODULE - 6 map of India, showing earthquake seisnic zones of different intensity. Its revised The Physical setting of India edition has been published in 2002. India has been divided into four zones. The intensity of each zone, result and losses caused by earthquake are described below: Zone II - The earthquake is felt by all, some people run outdoor. Heavy furniture may possibly move a little small pieces of plaster fall. Cracks in chimneys. Notes Zone III - Everyone runs out of doors, slight damage is there even in better designed and strongly built building. More breakage in ordinary bridges houses etc. Considerable damage to poorly designed and sub-standard buildings bridges etc. Zone IV - Slight damage in specially designed and well built building bridges etc. Heavy damage to poorly designed and badly built structures. Chimneys, poles, memorials, walls etc. fall down. Zone V - Severe damage to even well built bridges, buildings, foundations are displaced. Cracks and fissures develop in the ground. Practically all structures fall or small are greatly damaged or destroyed.

GEOGRAPHY

Fig. 18.4 INDIA Siesmic Zones

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Delhi and Mumbai are situated in high risk zone no. IV. The whole of North East India, Kachchh, Gujrat, Uttarakhand, Himachal Pradesh and Jammu & Kashmir are in the very high risk zone no. V. Now peninsular plateau is not safe from earthquakes. Earthquake of Latur (1993, intensity on rich for scale 6.4) and Koyna (1967 intensity 6.5) in Maharashtra testify it. Notes

Impact of Earthquake (i)

Damage of property : when earthquake occurs, all buildings from cottage to palaces and stronger skyscrapers are greatly damaged or totally destroyed. Underground pipelines and railway lines are damaged or broken. Dams on river collapse, resultant floods cause havoc. The earthquake in 1967 in Koyna damaged the Dam.

(ii) Human loss - Duration of tremors of earthquake is normally of only few seconds, but thousands of people may die in this short period. Five severely devastating earthquakes have occurred in India between 1988 and January 26, 2001. Nearly 31000 people lost their lives prematurely. Bihar earthquake of 1934 and Kangra earthquake of 1905, 10,000 and 20,000 people died respectively. Numerous people lost their shelter and many became orphans. The earthquake that occurred in Gujarat on 26 January, 2001 was devastating and disastrous. More than 25,000 people died due to the impact of this earthquake. The destruction of property was tremendous and could not be estimated properly and exactly. (iii) Changes in river courses: Sometimes river channels are blocked or their courses are changed due to the impact of earthquake. (iv) Tsunamis : are caused by earthquake. This is a Japanese word, meaning extremely high sea wave. It wreaks havoc on settlement of coastal areas. It sinks large ships. Tsunami that occurred on 26-12-2004 near coast of Sumatra (Indonesia) property worth billions of rupee. More than two lakh people lost their lives in Southeast Asia, India and Sri Lanka. (v) Fountains of mud : Due to the intense impact of earthquake hotwater and mud appear on the surface and take a form of fountains. In Bihar earthquake of 1934 some cracks and fissures had developed. The fields of farmer were covered by knee-deep mud and the crops were destroyed. (vi) Cracks and fissures : Sometimes cracks and fissures develop in roads railway tracks, and fields, making them useless. Well known san Andreas fault formed during the earthquake of San Fransisco (California). (vii) Landslides and avalanches are triggered Some Do’s and Don’t during and after the earthquake: Inside the house  Don’t run outside, set your family into-doorways, under table or if they are bedridden, more them under the beds; keep away from windows and chimneys. 64

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Outside the house 

Don’t go near the buildings, high walls, or electric wires.

While driving If an earthquake occurs stop driving and keep sitting in the vehicle.

Notes

To be done immediately (i)

Put off domestic fire, and all electrical switches.

(ii) Leave the house if possible and go to open space. (iii) Leave the house if a gas leak is detected after the gas is turned off. (iv) Save water (v) Untie and free pets and domestic animals (dogs, cats and cattles) Sudden shaking or trembling of the earth surface is an earthquake.  The whole North East India, Kachchh area of Gujarat, Himachal Pradesh, Uttaranchal and Jammu and Kashmir are in the very high risk zone No. 5. 

INTEXT QUESTION 18.5 1.

In which state did the earthquake occur on the occasion of Republic Day of 2001? ________________________________________________________ ________________________________________________________

2.

What names is given to the high sea-wave triggered by earthquake? ________________________________________________________ ________________________________________________________

3.

In which earthquake zone Delhi has been included on the basis of the tensity of the earthquakes? ________________________________________________________ ________________________________________________________

18.7 CYCLONES Cyclones are centers of low atmospheric pressure, in which the air pressure inGEOGRAPHY

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creases from the centre to the outer areas. Consequently winds flow from outside to the centres. In cyclones winds blow in an anticlock-wise direction in the northern hemisphere and in clock-wise in the southern hemisphere.

Notes

On the basis of their location and physical properties cyclones are of two types; temperate cyclones and tropical cyclones. Here a description of only tropical cyclone is given.The use of word ‘cyclone’ is implied for tropical cyclone here onwards.

Fig. 18.5 Way of Cyclones

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Cyclone is a violent circular stormy, in which high velocity winds blow from outside to the centre and are associated with torrential rain. Cyclones play an important role in the general circulation of the atmosphere. A fully developed cyclone can transfer 3.5 billion tons of warm humid air within an hour. When do cyclones occur? Cyclone is a phenomenon. It is concentrated to certain seasonal cyclic segment. In India, most of the cyclones occur in the post monsoon season, i.e. from October to December or in pre-monsoon season from April to May. The life span of a cyclone is generally from 7 to 14 days. The Movement of Cyclones The cyclone, with its whole system, moves forward from east to west (in Bay of Bengal) with a speed of 15 to 30 km per hour. The cyclone that struck orissa, originated near Andaman & Nicobar Islands and reached Orissa on 29-10-1999 after many days. The movement of cyclone in a direction is like the movement of a spinning top. Cyclones originate over the sea surface and dissipate as they reach land. Where do the cyclones strike in India The eastern coast of India is the most cyclone affected region. The cyclone prone states are; West Bengal, Orissa, Andhra Pradesh and Tamil Nadu: Western coast is affected by the cyclones which originate in the Arabian Sea. Gujarat on the west coast, is most affected by cyclones. The coastal areas and interior of Maharstra are affected by cyclones too. More cyclones originate in the Bay of Bengal and the Arabain Sea than any other seas of the world. Devastation by cyclones The violent winds of a cyclone destroy whatever come in their way from; thatched cottage to the palaces, forts built of concrete, iron and stones. Trees are uprooted. Lines of electricity and communication are destroyed. Torrential rains cause floods. Floods wreak havoc all around. High sea waves are generated in the sea by speedy cyclonic winds. They strike the coastal areas like high wall of water and flood the areas upto 10-15 km from the coast. In these areas houses, crops, roads, buildings, villages and cities one and all are submerged. Landslides triggered by cyclonic rains are more devastating. Developed countries have evolved measures to mitigate the fury of cyclones. The warning of cyclone is issued. They are broadcasted and telecasted at right time. This saves the life of people. On the contrary the people in developing countries get premature deaths. In USA, a fierce hurricane named Hugho struck in September 1989. Only 21 people lost their lives due to its impact, because a timely warming was issued, but contrary to this 1,39,000 people lost their lives in Bangladesh when a cyclone struck the country in 1991.

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Notes

Fig. 18.6 INDIA: Cyclone prone areas

Some do’s and don’ts before, during and after the cyclone

68 68



Listen to the radio for advance information and advice



Keep considerable margin of time for safety.



A cyclone may change direction, speed, or intensity within a few hours, so stay tuned to the radio for updated information. GEOGRAPHY GEOGRAPHY

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If high velocity winds or severe gales are forecasted for your area: 

Store or secure loose boards, corrugated iron sheets, old tin boxes, anything else that could become dangerous.



Close the windows tightly to prevent them from breakage.



Move to the safe shelter built for this purpose, or leave the area on the advice of some authoritative government agency.

Notes

When the storm strikes. 

Stay in the house and take shelter in the stronger portion of your house.



Listen to the radio and follow instructions.



Open windows of the safe portion of the house if the roof begins to lift.



Find shelter if you are in open at the hitting time of the cyclone.



Do not go out of your house or to a beach during or lay down along an elevated footpath in open field the storm. Cyclone often generates large surges in these oceans or lakes. 

Cyclone is violent circular storm. In its centre the air pressure is extremely low. High velocity winds flow towards the centre.



Most cyclone prone states of India are: West Bengal, Orissa, Andhra Pradesh and Tamil Nadu.

INTEXT QUESTIONS 18.6 1.

Which are the most cyclone prone months? ________________________________________________________

2.

Which state was hit by the seriously devastating cyclone on 29th of October, 1999? ________________________________________________________

3.

Which state is most valuable to cyclone on the western coast of India? ________________________________________________________

WHAT YOU HAVE LEARNT Among the top ten disaster prone countries, India stands second after China. More than 6% of the total population bear the brunt of natural disasters. Natural hazard, which devastates life and property, are called disasters. More than 20% GEOGRAPHY

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Notes

of the deaths caused by floods in the world, occur in India. Floods are caused by heavy rain, deposition of sediment and tsunami. 65% of cultivated area of India is rain fed. This is the area where droughts are common. Degradation of environment caused by human activities is also responsible for drought. By adopting some measures, the impact of drought could be mitigated. 191 districts, out of the 593 (2001) districts of India, are vulnerable to drought. Landslides cause heavy damage on mountainous slopes in rainy season. Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Sikkim and all the seven states of North East India are landslide prone. Landslides are caused by deforestation, earthquakes, construction of roads and buildings, and shifting agriculture. A very severe earthquake occurred on 26 January, 2001 in Gujarat. Earthquakes not only destroy life and property, but also changes the courses of rivers. Tsunami, mud fountains, cracks and fissures are also caused by severely devastating earthquakes. The quake prone areas are North East India, Gujarat, Uttarakhand, Himachal Pradesh and Jammu and Kashmir. Cyclones originate in the Bay of Bengal and affects the states of eastern coasts. Cyclones that originate in the Arabian Sea have a devastating impact over Maharashtra and Gujarat coast If some precise precautions are taken, the impact of cyclones could be mininised.

TERMINAL QUESTIONS 1.

Differentiate between natural hazard and natural disaster.

2.

What is a flood ? Explain the causes of flood and its destruction.

3.

Describe the drought prone areas of India.

4.

What is a landslide? What activities of human bening have increased the frequency of landslides.

5.

What is an earthquake? Describe its impact on humans.

6.

When do cyclones occur in India? Describe the measures adopted for protection from the cyclones.

ANSWERS TO INTEXT QUESTIONS 18.1 1. 70

When physical events pose danger to humans and their property, they are called hazards. GEOGRAPHY

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2.

Tsunami is large sea waves caused by earthquake below sea water. It causes heavy destruction to life and property on coastal areas thousands of kilometers away from its place of origin.

18.2

Notes

1.

Heavy rains, deforestation, cyclones, tsunami (any two).

2.

4 crore hectare.

3.

Construction of reservoires and embankments, tree plantation, restoration of natural drainage system.

18.3 1.

The rainfall deficiency during a long period, over a large area is called a drought.

2.

Rajasthan.

3.

Sprinkler irrigation.

18.4 1.

Earthquakes, volcanic explosions, heavy rain, deforestation, road construction, shifting agriculture (any two).

2.

Himalaya and Western Ghats.

3.

(i)

Tamil Nadu

(ii)

Cosntruction of strong wall on the slope.

18.5 1.

Gujarat

2.

Tsunami

3.

Zone No. IV

18.6 1.

October, Novemer, December, April and May

2.

Orissa

3.

Gujarat.

GEOGRAPHY

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HINTS TO TERMINAL QUESTIONS

Notes

72

1.

Refer to table No. 18.1

2.

Refer to 18.3

3.

Refer to 18.4

4.

Refer to 18.5

5.

Refer to 18.6

6.

Refer to 18.7

GEOGRAPHY