11 Geography Indian Physical Environment Goalias Blogspot (1)

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INTRODUCTION

This unit deals with

Location space relations and Indias place in the world

UNITI


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You have already seen the map of Indiain the previous classes. Now you closelyexamine the map of India (Figure 1.1).

Mark the southernmost and northernmostlatitudes and the easternmost and

westernmost longitudes.The mainland of India, extends from

Kashmir in the north to Kanniyakumari in thesouth and Arunachal Pradesh in the east toGujarat in the west. Indias territorial limitfurther extends towards the sea upto 12nautical miles (about 21.9 km) from the coast.

(See the box for conversion).

Statute mile = 63,360 inchesNautical mile = 72,960 inches1 Statute mile = about 1.6 km (1.584 km)1 Nautical mile = about 1.8 km (1.852 km)

Our southern boundary extends upto645' N latitude in the Bay of Bengal. Let ustry to analyse the implications of having sucha vast longitudinal and latitudinal extent.

If you work out the latitudinal andlongitudinal extent of India, they are roughly

about 30 degrees, whereas the actual distancemeasured from north to south extremity is3,214 km, and that from east to west is only2,933 km. What is the reason for thisdifference? Consult Chapter 3 on the topicLatitude, Longitude and Time in the book

Practical Work in Geography Part I (NCERT,2006) to find out.

This difference is based on the fact that thedistance between two longitudes decreasestowards the poles whereas the distance

between two latitudes remains the sameeverywhere. Find out the distance between twolatitudes?

From the values of latitude, it is understoodthat the southern part of the country lies

within the tropics and the northern part lies inthe sub-tropical zone or the warm temperate

zone. This location is responsible for largevariations in land forms, climate, soil types andnatural vegetation in the country.

Now, let us observe the longitudinal extentand its implications on the Indian people. Fromthe values of longitude, it is quite discerniblethat there is a variation of nearly 30 degrees,

which causes a time difference of nearly twohours between the easternmost and the

westernmost parts of our country. You arefamiliar with the concept of Indian Standard

Time (IST). What is the use of the standard

meridian? While the sun rises in thenortheastern states about two hours earlier ascompared to Jaisalmer, the watches inDibrugarh, Imphal in the east and Jaisalmer,Bhopal or Chennai in the other parts of Indiashow the same time. Why does this happen?

INDIA LOCATION

C H A P T E R

There is a general understanding among the countries of the world to select the standardmeridian in multiples of 730' of longitude. That is why 8230' E has been selected as thestandard meridian of India. Indian Standard Time is ahead of Greenwich Mean Time by5 hours and 30 minutes.

There are some countries where there are more than one standard meridian due totheir vast east-to-west extent. For example, the USA has seven time zones.


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3INDIA LOCATION

Figure 1.1 : India : Administrative Divisions


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4 INDIA : PHYSICAL ENVIRONMENT

Figure1.2:Location

ofIndiaintheEasternWorld


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5INDIA LOCATION

1. Choose the right answer from the four alternatives given below.

(i) Which one of the following latitudinal extent is relevant for the extent ofIndias area?

(a) 841'N - 357'N (c) 84'N - 356'N

(b) 84'N - 376'N (d) 645'N - 376'N

(ii) Which one of the following countries shares the longest land frontier withIndia?

(a) Bangladesh (c) Pakistan

(b) China (d) Myanmar

EXERCISES

Name a few place in India through which thestandard meridian passes?

India with its area of 3.28 million sq. kmaccounts for 2.4 per cent of the worlds landsurface area and stands as the seventhlargest country in the world. Find out thenames of the countries which are larger thanIndia.

SIZE

The size of India has endowed her with greatphysical diversity. Thus, you may appreciatethe presence of lofty mountains in the north;

large rivers such as Ganga, Brahmaputra,Mahanadi, Krishna, Godavari and Kaveri;green forested hills in northeast and southIndia; and the vast sandy expanse ofMarusthali. You may further appreciate that

bounded by the Himalayas in the north,Hindukush and Sulaiman ranges in the north-

west, Purvachal hills in the north-east and bythe large expanse of the Indian ocean in thesouth, it forms a great geographic entity knownas the Indian subcontinent. It includes thecountries Pakistan, Nepal, Bhutan,

Bangladesh and India. The Himalayas,together with other ranges, have acted as aformidable physical barrier in the past. Exceptfor a few mountain passes such as the Khyber,the Bolan, the Shipkila, the Nathula, theBomdila, etc. it was difficult to cross it. It hascontributed towards the evolving of a uniqueregional identity of the Indian subcontinent.

By referring to the physical map of Indiayou can now describe the physical variationswhich you would come across while travelling

from Kashmir to Kanniyakumari and fromJaisalmer in Rajasthan to Imphal in Manipur.

Peninsular part of India extends towardsthe Indian Ocean. This has provided thecountry with a coastline of 6,100 km in themainland and 7,517 km in the entiregeographical coast of the mainland plus theisland groups Andaman and Nicobar locatedin the Bay of Bengal and the Lakshadweep inthe Arabian Sea. Thus India, as a country, isa physically diverse land providing occurrenceof varied resources.

INDIAANDITSNEIGHBOURS

Examine the location map of India (Figure 1.2).You will notice that India is located in thesouth-central part of the continent of Asia,

bordering the Indian ocean and its two armsextending in the form of Bay of Bengal and the

Arabian Sea. This maritime location ofPeninsular India has provided links to itsneighbouring regions through the sea and airroutes.

Prepare a list of Indias neighbouringcountries by consulting the map.

Sri Lanka and Maldives are the two islandcountries located in the Indian Ocean, whichare our neighbours. Sri Lanka is separated fromIndia by the Gulf of Mannar and Palk Strait.

Differentiate between a Gulf and a Strait

Do you think that physical barrier is ahindrance in interaction with our neighbouringcountries in modern times? Give someexamples how we have overcome thesedifficulties in the present day.


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(iii) Which one of the following countries is larger in area than India?

(a) China (c) France

(b) Egypt (d) Iran

(iv) Which one of the following longitudes is the standard meridian for India?

(a) 6930'E (c) 7530'E

(b) 8230'E (d) 9030'E

2. Answer the following questions in about 30 words.

(i) Does India need to have more than one standard time? If yes, why do youthink so?

(ii) What are the implications of India having a long coastline?

(iii) How is the latitudinal spread of India advantageous to her?

(iv) While the sun rises earlier in the east, say Nagaland and also sets earlier,how do the watches at Kohima and New Delhi show the same time?

Project/Activity

Activity based on Appendix I (Teachers may help in the exercises by explainingand getting it done by the students).

(i) On a graph paper, plot the number of districts in Madhya Pradesh,Karnataka, Meghalaya, Goa, Kerala, Haryana. Do the number of districtshave some relationship with the area of the state?

(ii) Which state amongst Uttar Pradesh, West Bengal, Gujarat, ArunachalPradesh, Tamil Nadu, Tripura, Rajasthan and Jammu and Kashmir isthe most thickly populated and which one is the least densely populated?

(iii) Find out the relationship between the area of the state and the number ofdistricts.

(iv) Identify the states with coastal boundaries.(v) Arrange the states from west to east which have only land boundary.

Activity based on Appendix II

(i) List the Union Territories which have coastal location.

(ii) How do you explain the variation in the area and population of NCT Delhiand the Andaman and Nicobar Islands?

(iii) On a graph paper, draw a bar diagram to show the area and population ofall the Union Territories.


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PHYSIOGRAPHY

This unit deals with Structure and Relief; physiographic divisions

Drainage systems: concept of water sheds the Himalayanand the Peninsular

UNITII


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Do you know that our earth also has ahistory. The earth and its landformsthat we see today have evolved over a

very long time. Current estimation shows thatthe earth is approximately 460 million years old.Over these long years, it has undergone manychanges brought about primarily by theendogenic and exogenic forces. These forces haveplayed a significant role in giving shape to varioussurface and subsurface features of the earth. Youhave already studied about the Plate Tectonicsand the movement of the Earths plates in the

book Fundamentals of Physical Geography(NCERT, 2006). Do you know that the Indianplate was to the south of the equator millions of

years ago? Do you also know that it was muchlarger in size and the Australian plate was a partof it? Over millions of years, this plate broke intomany parts and the Australian plate movedtowards the southeastern direction and theIndian plate to the north. Can you map differentphases in the movement of the Indian plate? Thisnorthward movement of the Indian plate is stillcontinuing and it has significant consequenceson the physical environment of the Indiansubcontinent. Can you name some importantconsequences of the northward movement of theIndian plate?

It is primarily through the interplay of theseendogenic and exogenic forces and lateralmovements of the plates that the present geologicalstructure and geomorphologic processes activein the Indian subcontinent came into existence.Based on the variations in its geological structureand formations, India can be divided into threegeological divisions. These geological regions

broadly follow the physical features:

(i) The Penisular Block(ii) The Himalayas and other Peninuslar

Mountains

(iii) Indo-Ganga-Brahmaputra Plain.

THEPENINSULARBLOCK

The northern boundary of the PeninsularBlock may be taken as an irregular linerunning from Kachchh along the western flankof the Aravali Range near Delhi and thenroughly parallel to the Yamuna and the Gangaas far as the Rajmahal Hills and the Gangadelta. Apart from these, the Karbi Anglong andthe Meghalaya Plateau in the northeast andRajasthan in the west are also extensions of

this block. The northeastern parts areseparated by the Malda fault in West Bengalfrom the Chotanagpur plateau. In Rajasthan,the desert and other desertlike featuresoverlay this block.

The Peninsula is formed essentially by agreat complex of very ancient gneisses andgranites, which constitutes a major part of it.Since the Cambrian period, the Peninsula has

been standing like a rigid block with theexception of some of its western coast whichis submerged beneath the sea and some other

parts changed due to tectonic activity withoutaffecting the original basement. As a part ofthe Indo-Australian Plate, it has been subjectedto various vertical movements and blockfaulting. The rift valleys of the Narmada, the

Tapi and the Mahanadi and the Satpura blockmountains are some examples of it. ThePeninsula mostly consists of relictand residualmountains like the Aravali hills, the Nallamalahills, the Javadi hills, the Veliconda hills, the

STRUCTUREANDPHYSIOGRAPHY

C H A P T E R


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9STRUCTURE AND PHYSIOGRAPHY

Palkonda range and the Mahendragiri hills, etc.The river valleys here are shallow with lowgradients.

You are aware of the method of calculating

the gradient as a part of your study of the bookPractical Work in Geography Part I (NCERT,2006). Can you calculate the gradient of theHimalayan and the Peninsular rivers and drawthe comparisons?

Most of the east flowing rivers form deltasbefore entering into the Bay of Bengal. Thedeltas formed by the Mahanadi, the Krishna,the Kaveri and the Godavari are importantexamples.

THEHIMALAYASANDOTHER

PENINSULARMOUNTAINS

The Himalayas along with other Peninsularmountains are young, weak and flexible in theirgeological structure unlike the rigid and stablePeninsular Block. Consequently, they are stillsubjected to the interplay of exogenic andendogenic forces, resulting in the development offaults, folds and thrust plains. These mountainsare tectonic in origin, dissected by fast-flowingrivers which are in their youthful stage. Variouslandforms like gorges, V-shaped valleys, rapids,

waterfalls, etc. are indicative of this stage.

INDO-GANGA-BRAHMAPUTRAPLAIN

The third geological division of Ind iacomprises the plains formed by the riverIndus, the Ganga and the Brahmaputra.Originally, it was a geo-synclinal depression

which attained its maximum development

during the third phase of the Himalayanmountain formation approximately about 64million years ago. Since then, it has beengradually filled by the sediments brought by

the Himalayan and Peninsular rivers. Averagedepth of alluvial deposits in these plainsranges from 1,000-2,000 m.

It is evident from the above discussion thatthere are significant variations among thedifferent regions of India in terms of theirgeological structure, which has far-reachingimpact upon other related aspects. Variationsin the physiography and relief are importantamong these. The relief and physiography ofIndia has been greatly influenced by thegeological and geomorphological processes

active in the Indian subcontinent.

PHYSIOGRAPHY

Physiography of an area is the outcome ofstructure, process and the stage ofdevelopment. The land of India is characterised

by great diversity in its physical features. Thenorth has a vast expanse of rugged topographyconsisting of a series of mountain ranges with

varied peaks, beautiful valleys and deep gorges.The south consists of stable table land withhighly dissected plateaus, denuded rocks and

developed series of scarps. In between thesetwo lies the vast north Indian plain.

Based on these macro variations, India canbe divided into the following physiographicdivisions:

(i) The Northern and Northeastern Mountains(ii) The Northern Plain(iii) The Peninsular Plateau(iv) The Indian Desert(v) The Coastal Plains(vi) The Islands.

The North and Northeastern Mountains

The North and Northeastern Mountains consistof the Himalayas and the Northeastern hills.

The Himalayas consist of a series of parallelmountain ranges. Some of the important rangesare the Greater Himalayan range, whichincludes the Great Himalayas and the Trans-Himalayan range, the Middle Himalayas and

Figure 2.1 : A Gorge


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the Shiwalik. The general orientation of theseranges is from northwest to the southeastdirection in the northwestern part of India.Himalayas in the Darjiling and Sikkim regions

lie in an eastwest direction, while in ArunachalPradesh they are from southwest to thenorthwest direction. In Nagaland, Manipur andMizoram, they are in the northsouth direction.

The approximate length of the Great Himalayanrange, also known as the central axial range, is2,500 km from east to west, and their width

varies between 160-400 km from north tosouth. It is also evident from the map that theHimalayas stand almost like a strong and long

wall between the Indian subcontinent and theCentral and East Asian countries.

Himalayas are not only the physical barrier,they are also a climatic, drainage and culturaldivide. Can you identify the impact of Himalayas

on the geoenvironment of the countries of SouthAsia? Can you find some other examples ofsimilar geoenvironmental divide in the world?

There are large-scale regional variationswithin the Himalayas. On the basis of relief,alignment of ranges and other geomorphologicalfeatures, the Himalayas can be divided into thefollowing sub-divisions:

(i) Kashmir or Northwestern Himalayas(ii) Himachal and Uttaranchal Himalayas(iii) Darjiling and Sikkim Himalayas

(iv) Arunachal Himalayas(v) Eastern Hills and Mountains.

Kashmir or Northwestern Himalayas

It comprise a series of ranges such as theKarakoram, Ladakh, Zaskar and Pir Panjal. Thenortheastern part of the Kashmir Himalayas is acold desert, which lies between the GreaterHimalayas and the Karakoram ranges. Between

the Great Himalayas and the Pir Panjal range,lies the world famous valley of Kashmir and thefamous Dal Lake. Important glaciers of South

Asia such as the Baltoro and Siachen are also

found in this region. The Kashmir Himalayas arealso famous for Karewaformations, which are usefulfor the cultivation of Zafran,a local variety of saffron.Some of the importantpasses of the region are ZojiLa on the Great Himalayas,Banihal on the Pir Panjal,

Photu La on the Zaskar and Khardung La onthe Ladakh range. Some of the important freshlakes such as Dal and Wular and salt water lakessuch as Pangong Tso and Tso Moriri are also inthis region. This region is drained by the riverIndus, and its tributaries such as the Jhelumand the Chenab. The Kashmir and northwesternHimalayas are well-known for their scenic

beauty and picturesque landscape. Thelandscape of Himalayas is a major source ofattraction for adventure tourists. Do you knowthat some famous places of pilgrimage such as

Vaishno Devi, Amarnath Cave, Charar -e-Sharif,etc. are also located here and large number ofpilgrims visit these places every year?

Srinagar, capital city of the state of Jammu

and Kashmir is located on the banks of Jhelumriver. Dal Lake in Srinagar presents aninteresting physical feature. Jhelum in the valleyof Kashmir is still in its youth stage and yet formsmeanders a typical feature associated with themature stage in the evolution of fluvial land form(Figure 2.4). Can you name some other fluviallandforms in the mature stage of a river?

Figure 2.3 : The Himalayas

KarewasKarewas are thethick deposits ofglacial clay andother materialsembedded withmoraines.

Figure 2.4 : Meandering Jhelum


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The southernmost part of this region consistsof longitudinal valleys known as duns. Jammudun and Pathankot dun are important examples.

The Himachal and Uttaranchal Himalayas

This part lies approximately between the Raviin the west and the Kali (a tributary ofGhaghara) in the east. It is drained by two majorriver systems of India, i.e. the Indus and theGanga. Tributaries of the Indus include the riverRavi, the Beas and the Satluj, and thetributaries of Ganga flowing through thisregion include the Yamuna and the Ghaghara.

The northernmost part of the HimachalHimalayas is an extension of the Ladakh cold

desert, which lies in the Spiti subdivision ofdistrict Lahul and Spiti. All the three ranges ofHimalayas are prominent in this section also.

These are the Great Himalayan range, the LesserHimalayas (which is locally known asDhaoladhar in Himachal Pradesh and Nagtibhain Uttaranchal) and the Shiwalik range from theNorth to the South. In this section of LesserHimalayas, the altitude between 1,000-2,000m specially attracted to the British colonialadministration, and subsequently, some of the

important hill stations such as Dharamshala,Mussoorie, Shimla, Kaosani and thecantonment towns and health resorts such asShimla, Mussoorie, Kasauli, Almora,Lansdowne and Ranikhet, etc. were developedin this region.

The two distinguishing features of thisregion from the point of view of physiographyare the Shiwalik and Dun formations. Someimportant duns located in this region are the

An Interesting FactIn Kashmir Valley, the meanders in Jhelumriver are caused by the local base levelprovided by the erstwhile larger lake of whichthe present Dal Lake is a small part.

Figure 2.5 : Western Himalayas


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Chandigarh-Kalka dun, Nalagarh dun, DehraDun, Harike dun and the Kota dun, etc. DehraDun is the largest of all the duns with anapproximate length of 35-45 km and a width

of 22-25 km. In the Great Himalayan range,the valleys are mostly inhabited by theBhotias. These are nomadic groups whomigrate to Bugyals (the summer glasslandsin the higher reaches) during summer monthsand return to the valleys during winters. Thefamous Valley of flowers is also situated in thisregion. The places of pilgrimage such as theGangotri, Yamunotri, Kedarnath, Badrinathand Hemkund Sahib are also situated in thispart. The region is also known to have fivefamous Prayags (river confluences) as

mentiond in Chapter 3 of this book. Can youname some other famous prayags in otherparts of the country?

The Darjiling and Sikkim Himalayas

They are flanked by Nepal Himalayas in thewest and Bhutan Himalayas in the east. It isrelatively small but is a most significant partof the Himalayas. Known for its fast-flowing

rivers such as Tista, it is a region of highmountain peaks like Kanchenjunga

(Kanchengiri), and deep valleys. The higherreaches of this region are inhabited by Lepchatribes while the southern part, particularly theDarjiling Himalayas, has a mixed populationof Nepalis, Bengalis and tribals from CentralIndia. The British, taking advantage of thephysical conditions such as moderate slope,thick soil cover with high organic content, welldistributed rainfall throughout the year andmild winters, introduced tea plantations in thisregion. As compared to the other sections ofthe Himalayas, these along with the Arunachal

Himalayas are conspicuous by the absence ofthe Shiwalik formations. In place of theShiwaliks here, the duar formations areimportant, which have also been used for thedevelopment of tea gardens. Sikkim andDarjiling Himalayas are also known for theirscenic beauty and rich flora and fauna,particularly various types of orchids.

The Arunachal Himalayas

These extend from the east of the BhutanHimalayas up to the Diphu pass in the east.

The general direction of the mountain range isfrom southwest to northeast. Some of theimportant mountain peaks of the region areKangtu and Namcha Barwa. These ranges aredissected by fast-flowing rivers from the northto the south, forming deep gorges.Bhramaputra flows through a deep gorge aftercrossing Namcha Barwa. Some of theimportant rivers are the Kameng, the

The Shiwalik

The word shiwalik has its origin in thegeological formation found in and arounda place called Sivawala near Dehra Dunwhich was once a headquarter of theImperial Survey and which subsequentlyestablished its permanent headquartersat Dehra Dun.

Figure 2.6 : Himalayan Mountain Complex : Cross Sectional View from South to North

South North


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Subansiri, the Dihang, the Dibang and theLohit. These are perennial with the high rate offall, thus, having the highest hydro-electricpower potential in the country. An important

aspect of the Arunachal Himalayas is thenumerous ethnic tribal community inhabitingin these areas. Some of the prominent onesfrom west to east are the Monpa, Daffla, Abor,Mishmi, Nishi and the Nagas. Most of thesecommunities practise Jhumming. It is alsoknown as shifting or slash and burncultivation. This region is rich in biodiversity

which has been preserved by the indigenous

Figure 2.7 : Eastern Himalayas

communities. Due to rugged topography, theinter-valley transportation linkages arenominal. Hence, most of the interactions arecarried through the duar region along the

Arunachal-Assam border.

The Eastern Hills and Mountains

These are part of the Himalayan mountainsystem having their general alignment from thenorth to the south direction. They are known

by different local names. In the north, they areknown as Patkai Bum, Naga hills, the Manipur


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Figure 2.8 : Mizo Hills

Figure 2.9 : Loktak Lake

hills and in the south as Mizo or Lushai hills.These are low hills, inhabited by numeroustribal groups practising Jhum cultivation.

Most of these ranges are separated from eachother by numerous small rivers. The Barak isan important river in Manipur and Mizoram.

The physiography of Manipur is unique bythe presence of a large lake known as Loktaklake at the centre, surrounded by mountainsfrom all sides. Mizoram which is also knownas the Molassis basin which is made up of

soft unconsolidated deposits. Most of the riversin Nagaland form the tributary of theBrahmaputra. While two rivers of Mizoram andManipur are the tributaries of the Barak river,

which in turn is the tributary of Meghna; therivers in the eastern part of Manipur are thetributaries of Chindwin, which in turn is atributary of the Irrawady of Myanmar.

The Northern Plains

The northern plains are formed by thealluvial deposits brought by the rivers theIndus, the Ganga and the Brahmaputra.

These plains extend approximately 3,200 kmfrom the east to the west. The average widthof these plains varies between 150-300 km.

The maximum depth of alluvium depositsvaries between 1,000-2,000 m. From thenorth to the south, these can be divided intothree major zones: the Bhabar, the Taraiandthe alluvial plains. The alluvial plains can befurther divided into the Khadar and theBhangar.

Bhabar is a narrow belt ranging between8-10 km parallel to the Shiwalik foothills atthe break-up of the slope. As a result of this,the streams and rivers coming from themountains deposit heavy materials of rocksand boulders, and at times, disappear in thiszone. South of the Bhabaris the Taraibelt,

with an approximate width of 10-20 km wheremost of the streams and rivers re-emerge

without having any properly demarcatedchannel, thereby, creating marshy andswampy conditions known as the Tarai. Thishas a luxurious growth of natural vegetationand houses a varied wild life.

The south of Taraiis a belt consisting ofold and new alluvial deposits known as theBhangar and Khadar respectively. Theseplains have characteristic features of maturestage of fluvial erosional and depositionallandforms such as sand bars, meanders, ox-

bow lakes and braided channels. TheBrahmaputra plains are known for theirriverine islands and sand bars. Most of theseareas are subjected to periodic floods andshifting river courses forming braided streams.

The mouths of these mighty rivers also form

some of the largest deltas of the world, forexample, the famous Sunderbans delta.Otherwise, this is a featureless plain with ageneral elevation of 50-150 m above the meansea level. The states of Haryana and Delhi forma water divide between the Indus and theGanga river systems. As opposed to this, theBrahmaputra river flows from the northeast tothe southwest direction before it takes an


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Peninsular plateau is located on the Anaimalaihills of the Western Ghats followed by Dodabetta(2,637 m) on the Nilgiri hills. Most of thePeninsular rivers have their origin in the

Western Ghats. Eastern Ghats comprising thediscontinuous and low hills are highly eroded

by the rivers such as the Mahanadi, theGodavari, the Krishna, the Kaveri, etc. Some ofthe important ranges include the Javadi hills,the Palconda range, the Nallamala hills, theMahendragiri hills, etc. The Eastern and the

Western Ghats meet each other at the Nilgiri hills.

The Central Highlands

They are bounded to the west by the Aravalirange. The Satpura range is formed by a series

of scarped plateaus on the south, generally atan elevation varying between 600-900 m abovethe mean sea level. This forms thenorthernmost boundary of the Deccan plateau.It is a classic example of the relict mountains

wh ich are highl y denuded and formdiscontinuous ranges. The extension of thePeninsular plateau can be seen as far as

Jaisalmer in the West, where it has beencovered by the longitudinal sand ridges andcrescent-shaped sand dunes called barchans.

This region has undergone metamorphic

processes in its geological history, which canbe cor roborated by the presence ofmetamorphic rocks such as marble, slate,gneiss, etc.

The general elevation of the CentralHighlands ranges between 700-1,000 m abovethe mean sea level and it slopes towards thenorth and northeastern directions. Most of thetributaries of the river Yamuna have their originin the Vindhyan and Kaimur ranges. Banas isthe only significant tributary of the riverChambal that originates from the Aravalli in

the west. An eastern extension of the CentralHighland is formed by the Rajmahal hills, tothe south of which lies a large reserve ofmineral resources in the Chotanagpurplateau.

The Northeastern Plateau

In fact it is an extension of the main Peninsularplateau. It is believed that due to the force

exerted by the northeastward movement of theIndian plate at the time of the Himalayanorigin, a huge fault was created between theRajmahal hills and the Meghalaya plateau.

Later, this depression got filled up by thedeposition activity of the numerous rivers.

Today, the Meghalaya and Karbi Anglongplateau stand detached from the mainPeninsular Block. The Meghalaya plateau isfurther sub-divided into three: (i) The GaroHills; (ii) The Khasi Hills; (iii) The Jaintia Hills,named after the tribal groups inhabiting thisregion. An extension of this is also seen in theKarbi Anglong hills of Assam. Similar to theChotanagpur plateau, the Meghalaya plateauis also rich in mineral resources like coal, iron

ore, sillimanite, limestone and uranium. Thisarea receives maximum rainfall from the south

west monsoon. As a result, the Meghalayaplateau has a highly eroded surface.Cherrapunji displays a bare rocky surfacedevoid of any permanent vegetation cover.

The Indian Desert

To the northwest of the Aravali hills lies theGreat Indian desert. It is a land of undulatingtopography dotted with longitudinal dunesand barchans. This region receives low rainfall

below 150 mm per year; hence, it has aridclimate with low vegetation cover. It is becauseof these characteristic features that this is alsoknown as Marusthali. It is believed that

Figure 2.12 : The Indian Desert

Can you identify the type of sand dunes

shown in this picture?


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Kathiawar coast in Gujarat, Konkan coast inMaharashtra, Goan coast and Malabar coastin Karnataka and Kerala respectively. The

western coastal plains are narrow in the

middle and get broader towards north andsouth. The rivers flowing through this coastalplain do not form any delta. The Malabarcoast has got certain distinguishing featuresin the form of Kayals (backwaters), whichare used for fishing, inland navigation and alsodue to its special attraction for tourists. Every

year the famous Nehru Trophy Vallamkali(boat race) is held in Punnamada Kayal inKerala.

As compared to the western coastal plain,the eastern coastal plain is broader and is an

example of an emergent coast. There are well-developed deltas here, formed by the riversflowing eastward in to the Bay of Bengal. Theseinclude the deltas of the Mahanadi, theGodavari, the Krishna and the Kaveri. Becauseof its emergent nature, it has less number ofports and harbours. The continental shelfextends up to 500 km into the sea, whichmakes it difficult for the development of goodports and harbours. Name some ports on theeastern coast.

The IslandsThere are two major island groups in India one in the Bay of Bengal and the other in the

Arabian Sea. The Bay of Bengal island groupsconsist of about 572 islands/islets. These aresituated roughly between 6N-14N and92E -94E. The two principal groups of isletsinclude the Ritchies archipelago and theLabrynth island. The entire group of island is

Figure 2.13 : Coastal Plains

during the Mesozoic era, this region was underthe sea. This can be corroborated by theevidence available at wood fossils park at Aakaland marine deposits around Brahmsar, near

Jaisalmer (The approximate age of the wood-fossils is estimated to be 180 million years).

Though the underlying rock structure of thedesert is an extension of the Peninsularplateau, yet, due to extreme arid conditions,its surface features have been carved byphysical weathering and wind actions. Someof the well pronounced desert land featurespresent here are mushroom rocks, shiftingdunes and oasis (mostly in its southern part).On the basis of the orientation, the desert can

be divided into two parts: the northern part is

sloping towards Sindh and the southerntowards the Rann of Kachchh. Most of the riversin this region are ephemeral. The Luni riverflowing in the southern part of the desert is ofsome significance. Low precipitation and highevaporation makes it a water deficit region.

There are some streams which disappear afterflowing for some distance and present a typicalcase of inland drainage by joining a lake orplaya. The lakes and the playas have brackish

water which is the main source of obtaining salt.

The Coastal PlainsYou have already read that India has a longcoastline . On the basis of the location andactive geomorphological processes, it can be

broadly divided into two: (i) the western coastalplains; (ii) the eastern coastal plains.

The western coastal plains are an exampleof submerged coastal plain. It is believed thatthe city of Dwaraka which was once a part ofthe Indian mainland situated along the westcoast is submerged under water. Because ofthis submergence it is a narrow belt and

provides natural conditions for thedevelopment of ports and harbours. Kandla,Mazagaon, JLN port Navha Sheva, Marmagao,Mangalore, Cochin, etc. are some of theimportant natural ports located along the

west coast. Extending from the Gujarat coastin the north to the Kerala coast in the south,the western coast may be divided intofollowing divisions the Kachchh and


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Figure 2.14 : An Island

divided into two broad categories theAndaman in the north and the Nicobar in thesouth. They are separated by a water body

which is called the Ten degree channel. It isbelieved that these islands are an elevatedportion of submarine mountains. However,some smaller islands are volcanic in origin.Barren island, the only active volcano in Indiais also situated in the Nicobar islands.

Some important mountain peaks inAndaman and Nicobar islands are Saddle

peak (North Andaman 738 m), MountDiavolo (Middle Andaman 515 m), MountKoyob (South Andaman 460 m) andMount Thuiller (Great Nicobar 642 m).

The coastal line has some coral deposits,and beautiful beaches. These islands receiveconvectional rainfall and have an equatorialtype of vegetation.

The islands of the Arabian sea includeLakshadweep and Minicoy. These are scattered

between 8N-12N and 71E -74E longitude.These islands are located at a distance of

280 km-480 km off the Kerala coast. Theent ire island group is built of coral deposits.

There are approximately 36 islands of which11 are inhabited. Minicoyis the largest island

with an area of 453 sq. km. The entire groupof islands is broadly divided by the Eleventhdegree channel, north of which is the AminiIsland and to the south of the CanannoreIsland. The Islands of this archipelago havestorm beaches consisting of unconsolidatedpebbles, shingles, cobbles and boulders on theeastern seaboard.

On 26 December 2004, the Andaman and Nicobar islands experienced one of the mostdevasting natural calamity. Can you name the calamity and identify some other areaswhich were adversely affected by the same calamity? What was its major consequence?


(i) In which part of Himalayas do we find the Karewa formation?

(a) North-eastern Himalayas (c) Eastern Himalayas

(b) Himachal-Uttaranchal Himalayas (d) Kashmir Himalayas

(ii) In which of the following states is Loktak lake situated?

(a) Kerala (c) Manipur

(b) Uttaranchal (d) Rajasthan

(iii) Which one of the water bodies separates the Andaman from the Nicobar?

(a) 11 Channel (c) 10 Channel

(b) Gulf of Mannar (d) Andaman Sea

(iv) On which of the following hill range is the Dodabeta peak situated?

(a) Nilgiri hills (c) Cardamom hills

(b) Anaimalai hills (d) Nallamala hills


(i) If a person is to travel to Lakshadweep, from which coastal plain does heprefer and why?

EXERCISES


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(ii) Where in India will you find a cold desert? Name some important ranges ofthis region.

(iii) Why is the western coastal plain is devoid of any delta?

3. Answer the following questions in not more than 125 words.

(i) Make a comparison of the island groups of the Arabian Sea and the Bay ofBengal.

(ii) What are the important geomorphological features found in the river valleyplains?

(iii) If you move from Badrinath to Sunderbans delta along the course of theriver Ganga, what major geomorphological features will you come across?

Project/Activity

(i) Make a list of major Himalayan peaks from the west to the east with the helpof an atlas.

(ii) Identify the major landforms of your state and analyse the major economicactivity practised by the people in each landform.


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You have observed water flowing throughthe rivers, nalas and even channelsduring rainy season which drain the

excess water. Had these channels not beenthere, large-scale flooding would haveoccurred. Wherever channels are ill-defined orchoked, flooding is a common phenomenon.

The flow of water through well-definedchannels is known as drainage and thenetwork of such channels is called adrainage system. The drainage patternof an area is the outcome of the geologicaltime period, nature and structure ofrocks, topography, slope, amount ofwater fl owing and the periodic ity of

the flow.

Do you have a river near your village or city?Have you ever been there for boating or bathing?Is it perennial (always with water) or ephemeral(water during rainy season, and dry, otherwise)?Do you know that rivers flow in the samedirection? You have studied about slopes in theother two textbooks of geography (NCERT,

2006) in this class . Can you, then, explain thereason for water flowing from one direction tothe other? Why do the rivers originating from the

Himalayas in the northern India and the WesternGhat in the southern India flow towards the eastand discharge their waters in the Bay of Bengal?

A river drains the water collected from aspecific area, which is called its catchment area.

An area drained by a river and its tributariesis called a drainage basin. The boundary line

DRAINAGESYSTEM

C H A P T E R

Important Drainage Patterns

(i) The drainage pattern resembling the branches of a tree is known as dendritic the examples

of which are the rivers of northern plain.(ii) When the rivers originate from a hill and flow in all directions, the drainage pattern is known

as radial. The rivers originating from the Amarkantak range present a good example of it.(iii) When the primary tributaries of rivers flow parallel to each other and secondary tributaries

join them at right angles, the pattern is known as trellis.(iv) When the rivers discharge their waters from all directions in a lake or depression, the

pattern is know as centripetal.

Find out some of the patterns in the topo sheet given in Chapter 5 of Practical Work inGeography Part I (NCERT, 2006).

Figure 3.1 : A River in the Mountainous Region


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Figure 3.2 : Major Rivers of India


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23DRAINAGE SYSTEM

separating one drainage basin from the otheris known as the watershed.The catchments oflarge rivers are called river basins while thoseof small rivulets and rills are often referred to

as watersheds. There is, however, a slightdifference between a river basin and a

watershed. Watersheds are small in area whilethe basins cover larger areas.

River basins and watersheds are markedby unity. What happens in one part of thebasin or watershed directly affects the otherparts and the unit as a whole. That is why, theyare accepted as the most appropriate micro,meso or macro planning regions.

Indian drainage system may be divided onvarious bases. On the basis of discharge of water

(orientations to the sea), it may be grouped into:(i) the Arabian Sea drainage; and (ii) the Bay ofBengal drainage. They are separated from eachother through the Delhi ridge, the Aravalis andthe Sahyadris (water divide is shown by a linein Figure 3.1). Nearly 77 per cent of the drainagearea consisting of the Ganga, the Brahmaputra,the Mahanadi, the Krishna, etc. is orientedtowards the Bay of Bengal while 23 per centcomprising the Indus, the Narmada, the Tapi,the Mahi and the Periyar systems dischargetheir waters in the Arabian Sea.

On the basis of the size of the watershed,the drainage basins of India are grouped intothree categories: (i) Major river basins withmore than 20,000 sq. km of catchment area.It includes 14 drainage basins such as theGanga, the Brahmaputra, the Krishna, the

Tapi, the Narmada, the Mahi, the Pennar, theSabarmati, the Barak, etc. (Appendix III). (ii)Medium river basins with catchment area

between 2,000-20,000 sq. km incorporating44 river basins such as the Kalindi, the Periyar,the Meghna, etc. (iii) Minor river basins withcatchment area of less than 2,000 sq. km

include fairly good number of rivers flowing inthe area of low rainfall.

If you look at the Figure 3.1 you can seethat many rivers have their sources in theHimalayas and discharge their waters either inthe Bay of Bengal or in the Arabian Sea. Identifythese rivers of North India. Large rivers flowingon the Peninsular plateau have their origin inthe Western Ghats and discharge their waters

in the Bay of Bengal. Identify these rivers of theSouth India.

The Narmada and Tapi are two large riverswhich are exceptions. They along with many

small rivers discharge their waters in theArabian Sea.

Name these rivers of the western coastalregion from the Konkan to the Malabar coast.

On the basis of the mode of origin, natureand characteristics, the Indian drainage mayalso be classified into the Himalayan drainageand the Peninsular drainage. Although it hasthe problem of including the Chambal, theBetwa, the Son, etc. which are much older inage and origin than other rivers that have theirorigin in the Himalayas, it is the most accepted

basis of classification. Hence, this scheme hasbeen followed in this book.

DRAINAGESYSTEMSOFINDIA

Indian drainage system consists of a largenumber of small and big rivers. It is the outcomeof the evolutionary process of the three majorphysiographic units and the nature andcharacteristics of precipitation.

THEHIMALAYANDRAINAGE

The Himalayan drainage system has evolvedthrough a long geological history. It mainlyincludes the Ganga, the Indus and theBrahmaputra river basins. Since these are fed

both by melting of snow and precipitation,rivers of this system are perennial. These riverspass through the giant gorges carved out bythe erosional activity carried on simultaneously

with the uplift of the Himalayas. Besides deepgorges, these rivers also form V-shaped valleys,rapids and waterfalls in their mountainous

Figure 3.3 : Rapids


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course. While entering the plains, they formdepositional features like flat valleys, ox-bowlakes, flood plains, braided channels, anddeltas near the river mouth. In the Himalayan

reaches, the course of these rivers is highlytortous, but over the plains they display astrong meandering tendency and shift theircourses frequently. River Kosi, also know asthe sorrow of Bihar, has been notorious forfrequently changing its course. The Kosi bringshuge quantity of sediments from its upperreaches and deposits it in the plains. Thecourse gets blocked, and consequently, theriver changes its course. Why does the Kosiriver bring such huge quantity of sedimentsfrom the upper reaches? Do you think that

the discharge of the water in the rivers ingeneral and the Kosi in particular, remains thesame, or does it fluctuate? When does the rivercourse receive the maximum quantity of water?

What are the positive and negative effects offlooding?

EVOLUTIONOFTHEHIMALAYANDRAINAGE

There are difference of opinion about theevolution of the Himalayan rivers. However,geologists believe that a mighty river calledShiwalik or Indo-Brahma traversed the entire

longitudinal extent of the Himalaya from Assamto Punjab and onwards to Sind, and finallydischarged into the Gulf of Sind near lowerPunjab during the Miocene period some 5-24million years ago (See the table of geologicaltimes scale in Chapter 2 of Fundamentals ofPhysical Geography, NCERT, 2006). Theremarkable continuity of the Shiwalik and itslacustrine origin and alluvial depositsconsisting of sands, silt, clay, boulders andconglomerates support this viewpoint.

It is opined that in due course of time Indo

Brahma river was dismembered into three maindrainage systems: (i) the Indus and its fivetributaries in the western part; (ii) the Gangaand its Himalayan tributaries in the centralpart; and (iii) the stretch of the Brahmaputrain Assam and its Himalayan tributaries in theeastern part. The dismemberment wasprobably due to the Pleistocene upheaval inthe western Himalayas, including the uplift of

the Potwar Plateau (Delhi Ridge), which actedas the water divide between the Indus andGanga drainage systems. Likewise, the down-thrusting of the Malda gap area between the

Rajmahal hills and the Meghalaya plateauduring the mid-pleistocene period, diverted theGanga and the Brahmaputra systems to flowtowards the Bay of Bengal.

THERIVERSYSTEMSOFTHEHIMALAYANDRAINAGE

The Himalayan drainage consists of severalriver systems but the following are the majorriver systems:

The Indus System

It is one of the largest river basins of the world,covering an area of 11,65,000 sq. km (in Indiait is 321, 289 sq. km and a total length of 2,880km (in India 1,114 km). The Indus alsoknown as the Sindhu, is the westernmost ofthe Himalayan rivers in India. It originatesfrom a glacier near Bokhar Chu (3115' Nlatitude and 8140' E longitude) in the

Tibetan region at an altitude of 4,164 m inthe Kailash Mountain range. In Tibet, it isknown as Singi Khamban; or Lions mouth.

After flowing in the northwest directionbetween the Ladakh and Zaskar ranges, itpasses through Ladakh and Baltistan. It cutsacross the Ladakh range, forming aspectacular gorge near Gilgit in Jammu andKashmir. It enters into Pakistan near Chillarin the Dardistan region. Find out the areaknown as Dardistan.

The Indus receives a number of Himalayantributaries such as the Shyok, the Gilgit, theZaskar, the Hunza, the Nubra, the Shigar, theGasting and the Dras. It finally emerges out ofthe hills near Attock where it receives the Kabulriver on its right bank. The other importanttributaries joining the right bank of the Indusare the Khurram, the Tochi, the Gomal, the

Viboa and the Sangar. They all originate in theSulaiman ranges. The river flows southwardand receives Panjnad a little above Mithankot.

The Panjnad is the name given to the five riversof Punjab, namely the Satluj, the Beas, the Ravi,the Chenab and the Jhelum. It finally discharges


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25DRAINAGE SYSTEM

into the Arabian Sea, east of Karachi. The Indusflows in India only through the Leh district in

Jammu and Kashmir.The Jhelum, an important tributary of the

Indus, rises from a spring at Verinag situatedat the foot of the Pir Panjal in the south-easternpart of the valley of Kashmir. It flows throughSrinagar and the Wular lake before enteringPakistan through a deep narrow gorge. It joinsthe Chenab near Jhang in Pakistan.

The Chenab is the largest tributary of theIndus. It is formed by two streams, theChandra and the Bhaga, which join at

Tandi near Keylong in Himachal Pradesh.Hence, it is also known as Chandrabhaga.

The river flows for 1,180 km before entering

into Pakistan.The Ravi is another important tributary of

the Indus. It rises west of the Rohtang pass inthe Kullu hills of Himachal Pradesh and flowsthrough the Chamba valley of the state. Beforeentering Pakistan and joining the Chenab nearSarai Sidhu, it drains the area lying betweenthe southeastern part of the Pir Panjal and theDhauladhar ranges.

The Beas is another important tributary ofthe Indus, originating from the Beas Kund nearthe Rohtang Pass at an elevation of 4,000 m

above the mean sea level. The river flowsthrough the Kullu valley and forms gorges atKati and Largi in the Dhaoladhar range. Itenters the Punjab plains where it meets theSatluj near Harike.

The Satluj originates in the Rakas lake nearMansarovar at an altitude of 4,555 m in Tibet

where it is known as Langchen Khambab. Itflows almost parallel to the Indus for about 400km before entering India, and comes out of agorge at Rupar. It passes through the ShipkiLa on the Himalayan ranges and enters the

Punjab plains. It is an antecedent river. It is avery important tributary as it feeds the canalsystem of the Bhakra Nangal project.

The Ganga System

The Ganga is the most important river of Indiaboth from the point of view of its basin andcultural significance. It rises in the Gangotriglacier near Gaumukh (3,900 m) in the

Uttarkashi district of Uttaranchal. Here, it isknown as the Bhagirathi. It cuts through theCentral and the Lesser Himalayas in narrowgorges. At Devprayag, the Bhagirathi meets

the Alaknanda; hereafter, it is known as theGanga. The Alaknanda has its source in theSatopanth glacier above Badrinath. The

Alaknanda consists of the Dhauli and theVishnu Ganga which meet at Joshimath orVishnu Prayag. The other tributaries ofAlaknanda such as the Pindar join it at KarnaPrayag while Mandakini or Kali Ganga meetsit at Rudra Prayag. The Ganga enters theplains at Haridwar. From here, it flows first tothe south, then to the south-east and east

before splitting into two distributaries, namelythe Bhagirathi and the Hugli. The river has alength of 2,525 km. It is shared byUttaranchal (110 km) and Uttar Pradesh(1,450 km), Bihar (445 km) and West Bengal(520 km). The Ganga basin covers about 8.6lakh sq. km area in India alone. The Gangariver system is the largest in India having anumber of perennial and non-perennial riversoriginating in the Himalayas in the north andthe Peninsula in the south, respectively. TheSon is its major right bank tributary. Theimportant left bank tributaries are theRamganga, the Gomati, the Ghaghara, the

Gandak, the Kosi and the Mahanada. Theriver finally discharges itself into the Bay ofBengal near the Sagar Island.

The Yamuna, the western most and thelongest tributary of the Ganga, has its sourcein the Yamunotri glacier on the western slopesof Banderpunch range (6,316 km). It joins theGanga at Prayag (Allahabad). It is joined bythe Chambal, the Sind, the Betwa and the Kenon its right bank which originates from thePeninsular plateau while the Hindan, the Rind,the Sengar, the Varuna, etc. join it on its left

bank. Much of its water feeds the western andeastern Yamuna and the Agra canals forirrigation purposes.

Name the states which are drained bythe river Yamuna.

The Chambal rises near Mhow in theMalwa plateau of Madhya Pradesh and flowsnorthwards through a gorge up wards of Kota


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in Rajasthan, where the Gandhisagar dam hasbeen constructed. From Kota, it traverses downto Bundi, Sawai Madhopur and Dholpur, andfinally joins the Yamuna. The Chambal is

famous for its badland topography called theChambal ravines.

The Gandak comprises two streams,namely Kaligandak and Trishulganga. It risesin the Nepal Himalayas between the Dhaulagiriand Mount Everest and drains the central partof Nepal. It enters the Ganga plain inChamparan district of Bihar and joins theGanga at Sonpur near Patna.

The Ghaghara originates in the glaciers ofMapchachungo. After collecting the waters ofits tributaries Tila, Seti and Beri, it comes

out of the mountain, cutting a deep gorge atShishapani. The river Sarda (Kali or KaliGanga) joins it in the plain before it finally meetsthe Ganga at Chhapra.

The Kosi is an antecedent river with itssource to the north of Mount Everest in Tibet,

where its main stream Arun rises. Aftercrossing the Central Himalayas in Nepal, it is

joined by the Son Kosi from the West and theTamur Kosi from the east. It forms Sapt Kosiafter uniting with the river Arun.

The Ramganga is comparatively a small

river rising in the Garhwal hills near Gairsain.It changes its course to the southwest directionafter crossing the Shiwalik and enters into theplains of Uttar Pradesh near Najibabad. Finally,it joins the Ganga near Kannauj.

The Damodar occupies the eastern marginsof the Chotanagpur Plateau where it flowsthrough a rift valley and finally joins the Hugli.

The Barakar is its main tributary. Once knownas the sorrow of Bengal, the Damodar has

been now tamed by the Damodar Valleycorporation, a multipurpose project.

The Sarda or Saryu river rises in the Milanglacier in the Nepal Himalayas where it isknown as the Goriganga. Along the Indo-Nepal

border, it is called Kali or Chauk, where it joinsthe Ghaghara.

The Mahananda is another importanttributary of the Ganga rising in the Darjilinghills. It joins the Ganga as its last left banktributary in West Bengal.

The Son is a large south bank tributary of

the Ganga, originating in the Amarkantakplateau. After forming a series of waterfalls atthe edge of the plateau, it reaches Arrah, westof Patna, to join the Ganga.

The Brahmaputra System

The Brahmaputra, one of the largest riversof the world, has its origin in theChemayungdung glacier of the Kailash rangenear the Mansarovar lake. From here, ittraverses eastward longitudinally for adistance of nearly 1,200 km in a dry andflat region of southern Tibet, where it isknown as the Tsangpo, which means thepurifier. The Rango Tsangpo is the majorright bank tributary of this river in Tibet. It

emerges as a turbulent and dynamic riverafter carving out a deep gorge in the CentralHimalayas near Namcha Barwa (7,755 m).

The river emerges from the foothills underthe name of Siang or Dihang. It enters India

west of Sadiya town in Arunachal Pradesh.Flowing southwest, it receives its main left

bank tributaries, viz., Dibang or Sikang andLohit; thereafter, it is known as theBrahmaputra. The Brahmaputra receives numeroustributaries in its 750 km long journey through

the Assam valley. Its major left banktributaries are the Burhi Dihing, Dhansari(South) and Kalang whereas the important right

bank tributaries are the Subansiri, Kameng,Manas and Sankosh. The Subansiri which hasits origin in Tibet, is an antecedent river. TheBrahmaputra enters into Bangladesh nearDhubri and flows southward. In Bangladesh,the Tista joins it on its right bank from wherethe river is known as the Yamuna. It finallymerges with the river Padma, which falls in theBay of Bengal. The Brahmaputra is well-known

for floods, channel shifting and bank erosion.This is due to the fact that most of its tributariesare large, and bring large quantity of sedimentsowing to heavy rainfall in its catchment area.

THEPENINSULARDRAINAGESYSTEM

The Peninsular drainage system is older thanthe Himalayan one. This is evident from the

broad, largely-graded shallow valleys, and the


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Find out the name of the river on whichthe Gersoppa (Jog) fall is found.

Goa has two important rivers which can be

mentioned here. One is Mandovi and the otheris Juari. You can locate them on the map.

Kerala has a narrow coastline. The longestriver of Kerala, Bharathapuzha rises near

Annamalai hills. It is also known as Ponnani.It drains an area of 5,397 sq. km. Compare itscatchment area with that of the Sharavati riverof Karnataka.

The Periyar is the second largest river ofKerala. Its catchment area is 5,243 sq. km.

You can see that there is a marginal differencein the catchment area of the Bhartapuzha andthe Periyar rivers.

Another river of Kerala worth mentioning isthe Pamba river which falls in the Vemobanadlake after traversing a course of 177 km.

Teachers may explain the comparativeimportance of west flowing small rivers

River Catchment area

sq. km

Sabarmati 21,674Mahi 34,842Dhandhar 2,770Kalinadi 5,179Sharavati 2,029Bharathapuzha 5,397

Periyar 5,243

Small Rivers Flowing towards the East

There are a large number of rivers flowingtowards the east along with their tributaries.Can you name some of these rivers? There aresmall rivers which join the Bay of Bengal,though small, these are important in their ownright. The Subarnrekha, the Baitarni, theBrahmani, the Vamsadhara, the Penner, thePalar and the Vaigai are important rivers. Find

out these rivers from the atlas.Teachers may explain the comparativeimportance of east flowing small rivers

River Catchment area

sq. km

Subarnarekha 19,296Baitarni 12,789Brahmani 39,033Penner 55,213

Palar 17,870

in the north, it forms a picturesque gorge inmarble rocks and Dhuandhar waterfall near

Jabalpur. After flowing a distance of about1,312 km, it meets the Arabian sea south of

Bharuch, forming a broad 27 km long estuary.Its catchment area is about 98,796 sq. km. TheSardar Sarovar Project has been constructedon this river.

The Tapi is the other important westwardflowing river. It originates from Multai in the Betuldistrict of Madhya Pradesh. It is 724 km longand drains an area of 65,145 sq. km. Nearly 79per cent of its basin lies in Maharashtra, 15 percent in Madhya Pradesh and the remaining6 per cent in Gujarat.

Luni is the largest river system ofRajasthan, west of Aravali. It originates nearPushkar in two branches, i.e. the Saraswatiand the Sabarmati, which join with each otherat Govindgarh. From here, the river comes outof Aravali and is known as Luni. It flowstowards the west till Telwara and then takes asouthwest direction to join the Rann ofKuchchh. The entire river system is ephemeral.

Smaller Rivers Flowing Towards the West

The rivers flowing towards the Arabian seahave short courses. Why do they have shortcourses? Find out the smaller rivers ofGujarat. The Shetruniji is one such river

which rises near Dalkahwa in Amreli district.The Bhadra originates near Aniali village inRajkot district. The Dhadhar rises nearGhantar village in Panchmahal district.Sabarmati and Mahi are the two famous riversof Gujarat.

Find out the places of confluence of theserivers. Find out some important westflowing rivers of Maharashtra.

The Vaitarna rises from the Trimbak hillsin Nasik district at an elevation of 670 m. TheKalinadi rises from Belgaum district and fallsin the Karwar Bay. The source of Bedti riverlies in Hubli Dharwar and traverses a courseof 161 km. The Sharavati is another importantriver in Karnataka flowing towards the west.

The Sharavati originates in Shimoga districtof Karnataka and drains a catchment area of2,209 sq. km.


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29DRAINAGE SYSTEM

RIVERREGIMES

Do you know that the quantity of waterflowing in a river channel is not the samethroughout the year? It varies from seasonto season. In which season do you expect themaximum flow in Ganga and Kaveri? Thepattern of flow of water in a river channel overa year is known as its regime. The north Indianrivers originating from the Himalayas are

perennial as they are fed by glaciers throughsnow melt and also receive rainfall water duringrainy season. The rivers of South India do notoriginate from glaciers and their flow pattern

witnesses fluctuations. The flow increasesconsiderably during monsoon rains. Thus, theregime of the rivers of South India is controlled

by rainfall which also varies from one part ofthe Peninsular plateau to the other.

The discharge is the volume of water flowingin a river measured over time. It is measuredeither in cusecs (cubic feet per second) orcumecs (cubic metres per second).

The Ganga has its minimum flow duringthe January-June period. The maximum flowis attained either in August or in September.

After September, there is a steady fall in theflow. The river, thus, has a monsoon regimeduring the rainy season.

There are striking differences in the riverregimes in the eastern and the western partsof the Ganga Basin. The Ganga maintains a

sizeable flow in the early part of summer dueto snow melt before the monsoon rains begin.

The mean maximum discharge of the Gangaat Farakka is about 55,000 cusecs while themean minimum is only 1,300 cusecs. Whatfactors are responsible for such a largedifference?

The two Peninsular rivers displayinteresting differences in their regimescompared to the Himalayan rivers. The

Narmada has a very low volume of dischargefrom January to July but it suddenly rises in

August when the maximum flow is attained.The fall in October is as spectacular as the risein August. The flow of water in the Narmada,as recorded at Garudeshwar, shows that themaximum flow is of the order of 2,300 cusecs,

while the minimum flow is only 15 cusecs. TheGodavari has the minimum discharge in May,and the maximum in July-August. After

August, there is a sharp fall in water flowalthough the volume of flow in October and

November is higher than that in any of themonths from January to May. The meanmaximum discharge of the Godavari atPolavaram is 3,200 cusecs while the meanminimum flow is only 50 cusecs. These figuresgive an idea of the regime of the river.

EXTENTOFUSABILITYOFRIVERWATER

The rivers of India carry huge volumes of water

Table 3.1 : Comparison between the Himalayan and the Peninsular River

Sl. No. Aspects Himalayan River Peninsular River

1. Place of origin Peninsular plateau and central highland

2. Nature of flow Seasonal; dependent on monsoonrainfall

3. Type of drainage Super imposed, rejuvenated resultingin trellis, radial and rectangularpatterns

4. Nature of river Smaller, fixed course with well-adjustedvalleys

5. Catchment area Relatively smaller basin

6. Age of the river Old rivers with graded profile, and have

almost reached their base levels

Himalayan mountain covered withglaciers

Perennial; receive water from glacierand rainfall

Antecedent and consequent leading todendritic pattern in plains

Long course, flowing through therugged mountains experiencingheadward erosion and river capturing;In plains meandering and shifting ofcourse

Very large basins

Young and youthful , ac tive and

deepening in the valleys


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per year but it is unevenly distributed both intime and space. There are perennial riverscarrying water throughout the year while thenon-perennial rivers have very little water during

the dry season. During the rainy season, muchof the water is wasted in floods and flows downto the sea. Similarly, when there is a flood in onepart of the country, the other area suffers fromdrought. Why does this happen? Is it theproblem of availability of water resource or thatof its management? Can you suggest somemeasures to mitigate the problems of floods anddroughts simultaneously occuring in differentparts of the country? (See Chapter 7 of the book).

Can these problems be solved or minimisedby trasfering the surplus water from one basin

to the water deficit basins? Do we have someschemes of inter-basin linkage?

Teachers may explain the followingexamples

Periyar Diversion Scheme Indira Gandhi Canal Project Kurnool-Cuddapah Canal Beas-Satluj Link Canal Ganga-Kaveri Link Canal

Have you read in the newspapers about thelinking of rivers? Do you think that digging acanal is enough to transfer water from the Ganga

basin to the Peninsular river? What is the majorproblem? Consult Chapter 2 of this book and

find out the difficulties posed by theunevenness of the terrain. How can the water

be lifted from the plain area to the plateau area?Is there sufficient surplus water in the north

Indian rivers which can be transferred on aregular basis? Organise a debate on the wholeissue and prepare a write up. How do you rankthe following problems in using river water?

(i) No availability in sufficient quantity(ii) River water pollution(iii) Load of silt in the river water(iv) Uneven seasonal flow of water(v) River water disputes between states(vi) Shrinking of channels due to the extension

of settlements towards the thalweg.

Why are the rivers polluted? Have you seenthe dirty waters of cities entering into therivers? Where do the industrial affluents and

wastes get disposed of ? Most of the cremationgrounds are on the banks of rivers and thedead bodies are sometimes thrown in therivers. On the occasion of some festivals, theflowers and statues are immersed in the rivers.Large scale bathing and washing of clothesalso pollute river waters. How can the rivers

be made pollution free? Have you read aboutGanga Action Plan, or about a campaign forcleaning the Yamuna at Delhi? Collect

materials on schemes for making riverspollution free and organise the materials in a

write up.


(i) Which one of the following rivers was known as the Sorrow of Bengal?

(a) The Gandak (c) The Kosi

(b) The Son (d) The Damodar

(ii) Which one of the following rivers has the largest river basin in India?(a) The Indus (c) The Ganga

(b) The Brahmaputra (d) The Krishna

(iii ) Which one of the following rivers is not included in Panchnad?

(a) The Ravi (c) The Indus

(b) The Chenab (d) The Jhelum

(iv) Which one of the following rivers flows in a rift valley?

(a) The Son (c) The Yamuna (b) The Narmada (d) The Luni

EXERCISES


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31DRAINAGE SYSTEM

(v) Which one of the following is the place of confluence of the Alkananda and theBhagirathi?

(a) Vishnu Prayag (c) Karan Prayag

(b) Rudra Prayag (d) Deva Prayag

2. State the differences between the following.(i) River Basin and Watershed

(ii) Dendritic and Trellis drainage pattern

(iii ) Radial and Centripetal drainage pattern

(iv) Delta and Estuary


(i) What are the socio-economic advantages of inter-linking of rivers in India?

(ii) Write three characterstics of the Peninsular river.

4. Answer the following questions in not more than 125 words.

(i) What are the important characteristic features of north Indian rivers? How arethese different from Peninsular rivers?

(ii) Suppose you are travelling from Hardwar to Siliguri along the foothills of the

Himalayas. Name the important rivers you will come across. Describe thecharacteristics of any one of them.

Project/Activity

Study the Appendix III and answer the following questions.

(i) Which river has the largest proportion of catchment area in the country?

(ii) Make a comparative bar diagram on a graph paper to show the length of thecourses of the rivers.


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CLIMATE, VEGETATIONANDSOIL

This unit deals with Weather and climate spatial and temporal distribution of temperature,

pressure, winds and rainfall; Indian monsoons: mechanism, onset and

variability spatial and temporal; climatic types

Natural vegetation forest types and distribution; wild lifeconservation; biosphere reserves

Soils major types and their distribution, soil degradation andconservation

UNITIII


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We drink more water during summers.Your uniform during the summer isdifferent from the winters. Why do

you wear lighter clothes during summers andheavy woollen clothes during winters in northIndia? In southern India, woollen clothes arenot required. In northeastern states, wintersare mild except in the hills. There are variationsin weather conditions during different seasons.

These changes occur due to the changes in theelements of weather (temperature, pressure,

wind direction and velocity, humidity andprecipitation, etc.).

Weather is the momentary state of the

atmosphere while climate refers to theaverage of the weather conditions over a

longer period of time. Weather changes

quickly, may be within a day or week but

climate changes imperceptively and may

be noted after 50 years or even more.

You have already studied about themonsoon in your earlier classes. You are alsoaware of the meaning of the word, monsoon.Monsoon connotes the climate associated withseasonal reversal in the direction of winds.India has hot monsoonal climate which is theprevalent climate in south and southeast Asia.

UNITYANDDIVERSITYINTHEMONSOONCLIMATE

The monsoon regime emphasises the unity ofIndia with the rest of southeast Asian region.

This view of broad unity of the monsoon typeof climate should not, however, lead one toignore its regional variations which differentiate

the weather and climate of different regions ofIndia. For example, the climate of Kerala and

Tamil Nadu in the south are so different from

that of Uttar Pradesh and Bihar in the north,and yet all of these have a monsoon type ofclimate. The climate of India has many regional

variations expressed in the pattern of winds,temperature and rainfall, rhythm of seasonsand the degree of wetness or dryness. Theseregional diversities may be described assub-types of monsoon climate. Let us take acloser look at these regional variations intemperature, winds and rainfall.

While in the summer the mercuryoccasionally touches 55C in the western

Rajasthan, it drops down to as low as minus45C in winter around Leh. Churu in Rajasthanmay record a temperature of 50C or more on a

June day while the mercury hardly touches19C in Tawang (Arunachal Pradesh)on thesame day. On a December night, temperaturein Drass (Jammu and Kashmir) may drop downto minus 45C while Tiruvanantapuram orChennai on the same night records 20C or22C. These examples confirm that there areseasonal variations in temperature from placeto place and from region to region in India. Not

only this, if we take only a single place andrecord the temperature for just one day,

variations are no less striking. In Kerala and inthe Andaman Islands, the difference betweenday and night temperatures may be hardlyseven or eight degree Celsius. But in the Thardesert, if the day temperature is around 50C,at night, it may drop down considerably upto15-20C.

CLIMATEC H A P T E R


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Now, let us see the regional variations inprecipitation. While snowfall occurs in theHimalayas, it only rains over the rest of thecountry. Similarly, variations are noticeable not

only in the type of precipitation but also in itsamount. While Cherrapunji and Mawsynramin the Khasi Hills of Meghalaya receive rainfallover 1,080 cm in a year, Jaisalmer in Rajasthanrarely gets more than 9 cm of rainfall duringthe same period.

Tura si tuated in the Garo Hills ofMeghalaya may receive an amount of rainfallin a single day which is equal to 10 years ofrainfall at Jaisalmer. While the annualprecipitation is less than 10 cm in the north-

west Himalayas and the western deserts, it

exceeds 400 cm in Meghalaya.The Ganga delta and the coastal plains ofOrissa are hit by strong rain-bearing stormsalmost every third or fifth day in July and

August while the Coromandal coast, athousand km to the south, goes generally dryduring these months. Most parts of the countryget rainfall during June-September, but on thecoastal areas of Tamil Nadu, it rains in the

beginning of the winter season.In spite of these differences and variations,

the climate of India is monsoonal in rhythm

and character.

FACTORSDETERMININGTHECLIMATEOFINDIA

Indias climate is controlled by a number offactors which can be broadly divided into twogroups factors related to location and relief,and factors related to air pressure and winds.

Factors related to Location and Relief

Latitude :You already know the latitudinal andlongitudinal extent of the land of India. Youalso know that the Tropic of Cancer passesthrough the central part of India in east-westdirection. Thus, northern part of the India liesin sub-tropical and temperate zone and thepart lying south of the Tropic of Cancer falls inthe tropical zone. The tropical zone beingnearer to the equator, experiences hightemperatures throughout the year with smalldaily and annual range. Area north of the

Tropic of Cancer being away from the equator,

experiences extreme climate with high dailyand annual range of temperature.

The Himalayan Mountains :The lofty Himalayasin the north along with its extensions act as aneffective climatic divide. The towering mountainchain provides an invincible shield to protectthe subcontinent from the cold northern winds.

These cold and chilly winds originate near theArctic circle and blow across central and easternAsia. The Himalayas also trap the monsoonwinds, forcing them to shed their moisturewithin the subcontinent.

Distribution of Land and Water : India isflanked by the Indian Ocean on three sides inthe south and girdled by a high and

continuous mountain-wall in the north. Ascompared to the landmass, water heats up orcools down slowly. This differential heating ofland and sea creates different air pressurezones in different seasons in and around theIndian subcontinent. Difference in air pressurecauses reversal in the direction of monsoon

winds.

Distance from the Sea :With a long coastline,large coastal areas have an equable climate.

Areas in the interior of India are far away from

the moderating influence of the sea. Suchareas have extremes of climate. That is why,the people of Mumbai and the Konkan coasthave hardly any idea of extremes oftemperature and the seasonal rhythm of

weather. On the other hand, the seasonalcontrasts in weather at places in the interior ofthe country such as Delhi, Kanpur and

Amritsar affect the entire sphere of life.

Altitude :Temperature decreases with height.Due to thin air, places in the mountains are

cooler than places on the plains. For example,Agra and Darjiling are located on the samelatitude, but temperature of January in Agrais 16C whereas it is only 4C in Darjiling.

Relief :The physiography or relief of India alsoaffects the temperature, air pressure, directionand speed of wind and the amount anddistribution of rainfall. The windward sides of

Western Ghats and Assam receive high rainfall


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35CLIMATE

during June-September whereas the southernplateau remains dry due to its leewardsituation along the Western Ghats.

Factors Related to Air Pressure and WindTo understand the differences in local climatesof India, we need to understand themechanism of the following three factors:

(i) Distribution of air pressure and windson the surface of the earth.

(ii) Upper air circulation caused by factorscontrolling global weather and the inflowof different air masses and jet streams.

(iii) Inflow of western cyclones generallyknown as disturbances during the winter

season and tropical depressions duringthe south-west monsoon period intoIndia, creating weather conditionsfavourable to rainfall.

The mechanism of these three factors canbe understood with reference to winter andsummer seasons of the year separately.

Mechanism of Weather in the Winter Season

Surface Pressure and Winds : In wintermonths, the weather conditions over India aregenerally influenced by the distribution of

pressure in Central and Western Asia. A highpressure centre in the region lying to the northof the Himalayas develops during winter. Thiscentre of high pressure gives rise to the flow ofair at the low level from the north towards theIndian subcontinent, south of the mountainrange. The surface winds blowing out of the highpressure centre over Central Asia reach Indiain the form of a dry continental air mass. Thesecontinental winds come in contact with trade

winds over northwestern India. The position ofthis contact zone is not, however, stable.

Occasionally, it may shift its position as far eastas the middle Ganga valley with the result thatthe whole of the northwestern and northernIndia up to the middle Ganga valley comesunder the influence of dry northwestern winds.

Jet Stream and Upper Air Circulation : Thepattern of air circulation discussed above is

witnessed only at the lower level of theatmosphere near the surface of the earth. Higher

up in the lower troposphere, about three kmabove the surface of the earth, a different patternof air circulation is observed. The variations inthe atmospheric pressure closer to the surface

of the earth have no role to play in the making ofupper air circulation. All of Western and Central

Asia remains under the influence of westerlywinds along the altitude of 9-13 km from westto east. These winds blow across the Asiancontinent at latitudes north of the Himalayasroughly parallel to the Tibetan highlands(Figure 4.1). These are known as jet streams.

Tibetan highlands act as a barrier in the path ofthese jet streams. As a result, jet streams get

bifurcated. One of its branches blows to the northof the Tibetan highlands, while the southern

branch blows in an eastward direction, south ofthe Himalayas. It has its mean position at 25Nin February at 200-300 mb level. It is believedthat this southern branch of the jet streamexercises an important influence on the winter

weather in India.

Western Cyclonic Disturbance and Tropical

Cyclones :The western cyclonic disturbanceswhich enter the Indian subcontinent from the westand the northwest during the winter months,originate over the Mediterranean Sea and are

Figure 4.1 : Direction of Winds in India inWinter at the Height of 9-13 km


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brought into India by the westerly jet stream. Anincrease in the prevailing night temperaturegenerally indicates an advance in the arrival of thesecyclones disturbances.

Tropical cyclones originate over the Bay ofBengal and the Indian ocean. These tropicalcyclones have very high wind velocity and heavyrainfall and hit the Tamil Nadu, Andhra Pradeshand Orissa coast. Most of these cyclones are verydestructive due to high wind velocity and torrentialrain that accompanies it. Have you seen theirmovement in the weather report in the television?

Mechanism of Weather in the Summer Season

Surface Pressure and Winds :As the summersets in and the sun shifts northwards, the windcirculation over the subcontinent undergoesa complete reversal atboth, the lower as wellas the upper levels. By the middle of July, thelow pressure belt nearer the surface [termedas Inter Tropical Convergence Zone (ITCZ)]

shifts northwards, roughly parallel to theHimalayas between 20 N and 25 N. By thistime, the westerly jet stream withdraws fromthe Indian region. In fact, meteorologists have

found an interrelationship between thenorthward shift of the equatorial trough (ITCZ)and the withdrawal of the westerly jet streamfrom over the North Indian Plain. It is generally

believed that there is a cause and effectrelationship between the two. The ITCZ beinga zone of low pressure, attracts inflow of windsfrom different directions. The maritime tropicalairmass (mT) from the southern hemisphere,after crossing the equator, rushes to the lowpressure area in the general southwesterlydirection. It is this moist air current which ispopularly known as the southwest monsoon.

Jet Streams and Upper Air Circulation : Thepattern of pressure and winds as mentionedabove is formed only at the level of thetroposphere. An easterly jet stream flows over

Figure 4.2 : Summer Monsoon Winds : Surface Circulation


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37CLIMATE

the southern part of the Peninsula in June, andhas a maximum speed of 90 km per hour(Figure 4.3). In August, it is confined to 15oNlatitude, and in September up to 22oN latitudes.

The easterlies normally do not extend to the north

of 30o

N latitude in the upper atmosphere.

Easterly Jet Stream and Tropical Cyclones :Theeasterly jet stream steers the tropical

depressions into India. These depressions playa significant role in the distribution of monsoonrainfall over the Indian subcontinent. Thetracks of these depressions are the areas ofhighest rainfall in India. The frequency at whichthese depressions visit India, their directionand intensity, all go a long way in determiningthe rainfall pattern during the southwestmonsoon period.

Inter Tropical Convergence Zone (ITCZ)

The Inter Tropical Convergence Zone (ITCZ) is a low pressure zone located at the equatorwhere trade winds converge, and so, it is a zone where air tends to ascend. In July, theITCZ is located around 20N-25N latitudes (over the Gangetic plain), sometimes called

the monsoon trough. This monsoon trough encourages the development of thermal lowover north and northwest India. Due to the shift of ITCZ, the trade winds of the southernhemisphere cross the equator between 40 and 60E longitudes and start blowing fromsouthwest to northeast due to the Coriolis force. It becomes southwest monsoon. In winter,the ITCZ moves southward, and so the reversal of winds from northeast to south andsouthwest, takes place. They are called northeast monsoons.

THENATUREOFINDIANMONSOON

Monsoon is a familiar though a little knownclimatic phenomenon. Despite the observationsspread over centuries, the monsoon continuesto puzzle the scientists. Many attempts have

been made to discover the exact nature andcausation of monsoon, but so far, no singletheory has been able to explain the monsoonfully. A real breakthrough has come recently

when it was studied at the global rather thanat regional level.

Systematic studies of the causes of rainfallin the South Asian region help to understandthe causes and salient features of the monsoon,particularly some of its important aspects,such as:

(i) The onset of the monsoon.(ii) Rain-bearing systems (e.g. tropical

cyclones) and the relationship betweentheir frequency and distribution ofmonsoon rainfall.

(iii) Break in the monsoon.

Onset of the Monsoon

Towards the end of the nineteenth century, itwas believed that the differential heating ofland and sea during the summer months isthe mechanism which sets the stage for the

monsoon winds to drift towards thesubcontinent. During April and May when thesun shines vertically over the Tropic of Cancer,the large landmass in the north of Indian oceangets intensely heated. This causes theformation of an intense low pressure in thenorthwestern part of the subcontinent. Sincethe pressure in the Indian Ocean in the southof the landmass is high as water gets heated

Figure 4.3 : The Direction of Winds at 13 kmAltitude in Summer Season


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The shift in the position of the ITCZ is alsorelated to the phenomenon of the withdrawalof the westerly jet stream from its position overthe north Indian plain, south of the Himalayas.

The easterly jet stream sets in along 15Nlatitude only after the western jet stream has

withdrawn itself from the region. This easterlyjet stream is held responsible for the burst ofthe monsoon in India.

Entry of Monsoon into India :The southwestmonsoon sets in over the Kerala coast by 1st

June and moves swiftly to reach Mumbai andKolkata between 10th and 13th June. By mid-

July, southwest monsoon engulfs the entiresubcontinent (Figure 4.5)

Rain-bearing Systems and RainfallDistribution

There seem to be two rain-be

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