Wednesday, October 28, 2009


MARSHES AND BOGS A bog is an area of wet, spongy ground, of decomposing moss and other veg­etation, on the surface of a shallow pond or lake. Marshes and swamps are poorly drained, low-lying tracts of land that possess distinct flora. These are places where water stands at or close to the ground surface over a broad area. Some emerge by shifting of river channels on flood plains, while others emerge from the sea. Rushes, reeds and certain mosses are characteristic of marshland. A marsh may be drained to provide agricultural land as has occurred in the Fens of East Anglia.


Some of the important lakes in India are-Oal and Wular lakes in Jammu and Kashmir; Chllka lake in Orissa;Ohebar, Sambhar and Pushkar lakes in Rajasthan; Bhimtal, Satta or Satta I and Roop Kund in Uttarakhand; BhoJ wetland in Bhopal (M.P.); Chandratal, KhaJjlar, Nake, Renuka lakes in Himachal Pradesh; Pulicat lake on the Coromandel Coast on the Andhra Pradesh-Tamil Nadu border; Chembarambakkam. Kalivell and Veeranam lakes in Tamil Nadu; Hussain Sagar Himayat Sagar and Osman Sagar lakes in Hyderabad and Kolleru in Andhra Pradesh; Loktal (also called Floating Lake) in north­east India; Khecheopalrl and Tsongmo lakes in Sikkim; Vembanad, Vembanattu and Veeranpuzha lakes in Kerala.


A lake is a body of water that lies in a hollow on. the earth's surface and is entirely surrounded by land. It is unconnected with the sea except by rivers. In arid and semi­arid areas lakes may have no outlet to the sea and form the focus of an area of inland drainage. As a result the water of the lake becomes increasingly saline. Some inland seas are actually large lakes, e.g:, the Caspian Sea, Dead Sea artd Aral Sea.

CLASSIFICATION OF LAKES Though most lakes have been formed by the action of glaciers and icesheets, others have been formed by rivers, marine and wind action, by earth movement and vulcanicity, and a few lakes are also man-made. Some basic categories may be considered.

(i) Lakes produced by earth movements These are lakes formed by tectonic forces. They may be formed in two ways. (a) By crustal warping. These occupy basin-like depressions e.g., Caspian Sea, Lake Victoria (Africa), Lake Eyre (Australia). Lake Titicaca (Peru/Bolivia) is the highest tectonic lake in the world. (b) By faulting. These occur in rift valleys, e.g., Lake Nyasa (East Africa), the Dead Sea and Loch Ness (Scotland). These lakes are usually long, narrow and deep.
(ii) Lakes formed by erosion They may be of two types.
a) Both valley glaciers and ice sheets gouge out hollows and troughs on earth surface which later get filled with water to form lakes. These may be cirque lakes, forming in arm-chain-like depressions, also called tarns, found in moun­tain regions, or they may be trough lakes which occupy long hollows excavated in valley bottoms, also called ribbon lakes. They may also be rock basin lakes, formed by ice-scouring action of ice sheets resulting in formation of shallow hollows, as in Canada and Finland.
(b) Wind-eroded lakes: In the extensive depressions which are created by wind-erosion in the arid regions, if excavation is carried out below the water table, a lake may develop; e.g., the Qattara Depression in Egypt. Oases formed out of aquifers are more permanent lakes. Some desert lakes-palaya, for example-dry up be­cause of excessive evaporation.

(iii) Lakes produced by deposition These may be of the following kinds. (a) River deposits: Ox-bow lakes _are cut­offs of mature rivers, made in flood plains, which even­tually get separated from the river. They are common in lower valleys of the Mississippi. Deposits of alluvium in deltas may isolate a distributary, thus producing a delta lake, e.g., Etang de Vaccares in the Rhone Delta.
(b) Lakes produced by glacial deposits: Moraine-dammed lakes are caused by the deposition of terminal moraine across a valley, e.g., in the Lake District (England). Lake Grade (Italy) was formed like this. Depressions in boulder clay result in lake formation, such as the lakes in Northern Ireland.
(c) Marine deposits can form lakes: They are called Haffs. These lakes have been formed by sand bars extend­ing along a coast and cutting off indentations in the coast, thus producing lagoons. These are found in southern coast of Baltic Sea and along Les Landes coast of south-west France.
(iv) Lakes produced by vulcanicity
(a) Crater and caldera lakes: Craters are formed when the top of a volcano gets blown off in a violent eruption. A caldera is formed if a crater gets enlarged by subsidence. Examples are Crater Lake in Oregon (USA), Lake Toba in north Sumatra and Lake Knebel in Iceland.
(b) Lava-blocked lakes: River valleys get blocked by lava to form a lake; the Sea of Galilee was formed by lava-flow blocking Jordan valley.
(c) Lava­subsidence lakes: These are caused by depressions caused by collapse of the lava crust, e.g., Myvatn, in Iceland.

(v) Other Types
(a) Solution lakes: Some rocks are dissolved and removed by rain water. This produces underground caverns. Limestone caverns collapse to ex­pose lakes which are usually long and narrow, e.g., Lac de Chailexon in Jura Mountain. Sometimes, solution, aided by subsidence, produces large depressions called polje. Rock salt has been removed by solution in Cheshire (England) and the depressions have formed containing lakes, called 'flashes'.
(b) Barrier lakes: These are temporary lakes formed by ice, lava, moraine damming a valley, or damming by landslides, avalanches or screes.
(c) Beaver lakes: These are created by some animals like beavers which build dams across the streams to form lakes, e.g., Beaver lake in Yellow Stone National Park (USA).
(d) Mining ponds: These are caused by open cast mining, e.g., by tin mining in West Malaysia. (e) Man-made lakes: These are artificial lakes made by building dams across rivers.

Importance and Use Lakes play an important role. They are used for communication as natural routes; for hydro-electric power development; for regulating the flow of rivers; as a source for fishery; for water storage; for providing irrigating water. They also moderate the climate.


Himalayan Rivers

Nature of flow Perennial as dependent Seasonal dependent on rainfall as well as snow melt rainfall alone

Catchment areaVery large basins

ErosionDeep valleys and gorges in the Himalaya due to intensive erosion

Nature of the course Meandering course and shifting beds in the Great plains

Other featuresV-shaped valleys, high waterfalls and huge delta.

Penisular Rivers

Nature of flowSeasonal dependent on rainfall alone
Catchment area Erosion Shallow graded valleys with little erosion

Nature of the course Straight and linear course.

Other features Shallow valleys, small waterfalls, delta and estuaries.

Major Rivers of India

Name of River   Origin    Destination   Length   Basin Area  Average annual discharge

1. Ganga              Gangotri Glacier, Uttar Kashi    Bay of Bengal    2,525    8,61,404    4,93,400      
2. Indus               Mansarovar Lake, Tibet    Arabian Sea    1,270    3,21,290    41,955      
3. Godavari          Nasik, Maharashtra    Bay of Bengal    1 ,465    3,12,812    1,05,000      
4. Krishna            Mahabaleshwar,    Maharashtra    Bay of Bengal    1,400    2,58,948    67,675      
5. Brahmaputra    Kailash Range, China    Bay of Bengal    720    1,87,110    5,10,450      
6. Mahanadi         Raipur (Chhattisgarh)    Bay of Bengal    857    1,41,600    66,640      
7. Narmada          Amarkantak, Madhya Pradesh    Arabian Sea    1,312    98,796    40,705      
8. Cauvery           Kodagu (Brahmagiri Hills), Karnataka    Bay of Bengal    800    87,900    20,950      
9. Tapi                 Betul, Madhya Pradesh    Gulf of Khambhat    724    65,145    17,982      
10. Pennar           Chennakesva Hills (Kolar) Karnataka    Bay of Bengal    597    55,213    3,238      
11. Brahmni          Ranchi, Jharkhand    Bay of Bengal    800    39,033    18,310      
12. Mahi               Ratlam (Gwalior), Madhya Pradesh    Gulf of Khambhat    533    34,842    8,500      
13. Sabarmati        Aravalli Hills (Gujarat)    Gulf of Khambhat    300    21,674    3,200     

Note: BAsin Area in India= in Sq. Km.
         Annual Discharge in million cubic metre

Peninsular Component

1. Mahanadi. Burhabalang
2. Mahanadi. Godavari
3. Indravati. Wainganga
4. Wainganga. Krishna
5. Krishna (Srisailam) . Pennar (Prodattur)
6. Pennar (Gandikotta) . Palar - Cauvery
7. Cauvery. Vaigai
8. Godavari (Ichampalli) . Krishna (Nagarjunasagar)
9. Krishna (Nagarjunasagar) . Pennar (Somasila)
9A.Krishna (Almatti) . Pennar
10. Pennar (Somasila) . Palar. Cauvery (Coleroon)
11. Godavari (Ichampalli) . Krishna (Pulichintala)
12.Godavari (Polavaram). Krishna (Vijayawada)
13. Par. Tapi . Narmada
14. Damanganga . Tansal Pinjal
15. West flowing rivers of Kerala and Kamataka
(West. East link)
(i). Beoti. Varda
(ii). Netravati . Hemavati
(iu).Pamba. Achankovil. Vaippar
16.Ken. Betwa
17. Parbati - Kalisindh . Chambal

All River Systems

Indus System
@ Jhelum
@ Chenab
@ Ravi
@ Satluj
@ Beas

Ganaa System
@ Ganga
@ Yamuna
@ Ramganga
@ Ghaghra
@ Gandak
@ Burhi Gandak
@ Baghmati
@ Kosi
@ Chambal
@ Kali Sindh
@ Betwa
@ Son
@ Rihand
@ Damodar
@ Banas
@ Luni
@ Sabarmati
@ Mahi
@ Narmada
@ Tapti .
@ Subarnarekha
@ South KoellBrahmani/Mahanadi

Godavari System
@ Godavari
@ penganga
@ Manjara
@) Wardha
@ Waiganga
@ Indravati

Krishna System
@ Krishna
@ Bhima
@ Tungabhadra
@North Pennar
@ South Pennar
@ Cauvery
@ Waigai

Himalayan Component

1. Kosi - Mechi
2. kosi - Ghagra
3. Gandak - Ganga
4. Ghagra - Yamuna
5. Sarda - Yamuna
6. Yamuna - Rajasthan
7. Rajasthan - Sabarmati
8. Chunar - Sone barrage
9. Sone dam. Southern tributaries of Ganga
10. Brahmaputra - Ganga (MSTG)
11. Brahmaputra - Ganga (JTF) (ALT)
12. Farakka - Damodar . Subarnarekha
13. Ganga - Damodar - Subarnarekha
14. Subarnarekha - Mahanadi


Suggestions for a National Water Grid envisaging interlinking of rivers with a view to transferring surplus water available in some regions to water deficit areas have been made from time to time. The Govemment of India prepared a national perspective plan for water resources development in 1980 envisaging interlinkages be­tween various peninsular rivers and Himalayan rivers for transfer of water from water-surplus basins for optimum utilisation of water resources. The Government of India established the National Water Development Agency (NWDA) in 1982 to firm up these proposals.

In December 2004, the Centre set up a committee of experts to advise the government on environ­mental and socio-economic aspects of the interlinking programme.

The total amount of water that can be usefully transferred is esti­mated to be about 220 bcm. However, there are apprehensions that the assessed surplus is somewhat illu­sory for many basins and future generations would actually need all the water. Sceptics have reservations about the economic viability of such large projects. Environmental concerns would need to be addressed through the environmental appraisal process of each project. For these reasons the pace of progress in the Tenth Plan period has been quite modest.

Per capita availability of water varies from 18.417 m3 in the Brahmaputra river to 380 m3 in some east-flowing rivers in Tamil Nadu showing that many basins in the country are already critically starved of water. Out of the annual precipitation and snowfall of 4000 bern, 747 bcm runs waste to the sea, mainly from the Ganga and Brahmaputra rivers systems, which have 60 per cent of the water potential. Only 19 per cent of the water potential is available in Maha[1adi, Godavari, Krishna and Cauvery.
In the circumstances, inter-linking of rivers as­sumes importance as a part of the 747 bcm running waste to sea (about 160-220 bcm) is proposed to be transferred through a series of 30 inter-linking proposals from- surplus basins to deficit basins. Long-distance, trans-basin transfer of water is not a new concept.

Many examples of existing projects can be given in this regard-Western Yamuna canal, Periyar project, Kumool Cuddapah canal, Indira Gandhi canal, and Sardar Sarovar canal. International examples can be given of California water transfer project from north to central and southern parts of the US, China, the erstwhile USSR, Sri Lanka, and Mexico. Pioneering work was earlier done on a National Water Grid by K.L. Rao and Capt. Dastur. These were refined by the MoWR and 30 links identified-16 as peninsular component and 14 as Himalayan component. Pre-feasibility studies of 16 links (14 in peninsular component) have also been completed.

Since interlinking rivers on such a large scale is bit costly, evaluation of the economics of the proposals is necessary. Environmental impacts have to be care­fully assessed.



India has a large number of waterfalls spread ae'ross the country. Some of the important ones are-the Agaya Gangai in the Kolli Hills (Eastern Ghats), Ayyanar in Virudhunagar, Killyur in Servarayan Hill of Eastern Ghats, Siruvanl in Coimbatore, Thalaiyar (also known as Rat-Tail) near Kodaikanal and Vattaparai in the Pazhayar river in Kanyakumari (all in Tamil Nadu); Barakana in Shimoga, Gokak in the upper reaches of the Ghataprabha (a tributary of Krishna) in Belgaum, Jog (Gersoppa and Jogada Gundi) on the Sharavathi river in Shimoga. Shivasamudram (also known as Cauvery falls (also in Kamataka); Vazhachal in Thrissur in Kerala; Dudhsagar fall in upper reaches of Mandavi river in Goa; Lodh (or Buddha Ghagh) falls on the Budh river in Ranch; in Jharkhand; and Duduma waterfall in Koraput in Orissa.



The pattern of the seasonal flow of water in any river is called its regime. Differences in climate are the main cause of the differences in the flow patterns of rivers of the Himalayan and peninsular origin. The Himalayan rivers are perennial and their regimes depend upon both rainfall and :mow. Thus, the regimes of the Himalayan rivers are both monsoonal and glacial. On the other hand, the regimes of the Peninsular rivers are only monsoonal as they are controlled only by rainfall. There also exist the intra­peninsular differences in the river regimes. This is due to differences in the seasonal distribution of rainfall in various parts of the plateau.

The regimes of the two Himalayan (Ganga and Jhelum) and the two penin­sular (Narmada and Godavari) rivers may be described as examples of the river regimes.

The Ganga has its minimum flow in the period January-June. The maximum is attained either in August or September. There is a steady fall in the flow of water after September. The river has a typical monsoonal regime. The Jhelum attains the maximum water flow in June, or even in May, since its flow is mainly caused by the snow-melt from the Himalayas. The range of variation between the regimes of the Ganga and the Jhelum rivers is shorter in the case of the former.

The two peninsular rivers display interesting differences in their regimes from the Himalayan rivers. The Narmada attains its maxi­mum water flow in August, while it has a very low volume of discharge from January to July. The Godavari flows at a low level until May. It attains maximum water flow twice-one in May-June and the other in July-August.


(i) Though the Indus is a perennial river, much of its water is lost as it flows through the Thar Desert. The delta formed by this river is mostly wasteland, since it is usually flooded with brackish water.
(ii) River Brahmaputra has different names in different countries: Tsang-po in Tibet (China); Brahmaputra in India; and Jamuna in Bangladesh. During floods, the water of the Brahmaputra looks reddish in colour after mixing with the red soils of Assam. This is why the Brahmaputra is also known as the 'Red River' of India.
(iii) The Ganga basin forms 25 per cent of the total area of India. It is the longest river in the country. The Ganga and the Brahmaputra flow in opposite direction to meet together in Bangladesh where they form the largest delta of the world. The major part of the Ganga-Brahmaputra delta lies in Bangladesh.
(iv) Gaumukh (meaning cow's mouth), an ice cave in the Himalayas, is the source of the Ganga.
(v) The Yamuna is the most important tributary on the right bank of River Ganga. Gomati, Ghaghara, Gandak and Koshi join the Ganga on the left bank. The Son is the only big river to join the Ganga directly from the southern plateau (right bank).
(vi) River Damodar is known as the 'Sorrow of Bengal' as it causes widespread destruction of lives, cattle and crops due to frequent flooding. It joins the Ganga from the right.
(vii) Some rivers of the Peninsular Plateau flow towards Ganga, e.g., Chambal, Betwa, Ken, Sind and Son. These rivers rise in the Vindhya range.
(viii) The Cauvery plunges from a height of 100 m at Sivasamundram forming the famous Sivasamundram Falls.
(ix) River Sharavati in the state of Karnataka is fam9us for its Gersoppa (Jog Falls). These falls can be considered as one of the world's greatest waterfalls in the rainy season. But like other peninsular rivers, the Sharavati has very little water in the dry season.
(x) The Narmada forms the magnificent waterfall (Marble Falls of Bheraghat in Madhya Pradesh). The waterfall is 15 m high.
(xi) The Ganga, Brahmaputra, Mahanadi. Godavari, Krishna and Cauvery are the major river systems of India draining into the Bay of Bengal, whereas the major river systems flowing into the Arabian Sea include the Indus, Sabarmati, Narmada and Tapti.
(xii) While Godavari is the largest river system in Pen­insular India, it is the second largest (next only to the Ganga System) in India as a whole.
(xiii) The Cauvery basin is one of the most developed regions of India from the point of view of power and irrigation. It is estimated that about 90-95 per cent of the total potential in both these resources has already been exploited.

The West-flowing Rivers

The West-flowing Rivers The rivers flowing west are discussed below.
The Narmada It rises from a tank 1057 m high on the west of the Amarkantak plateau in Madhya Pradesh. It is the largest of the west-flowing peninsular rivers. Flowing along Ramnagar and Mandla, it turns towards Jabalpur where it cascades down to make the narrow gorge of 'Marble Rocks' after dropping from 10 metres of height (Dhuandhara falls). It then flows westwards for 320 km between the Vindhya and Satpura ranges. It also forms the famous 23 m high Kapildhara falls. It flows through the alluvial plains of Indore to form a 27-km broad estuary below Broach and enters the Gulf of Cambay. The 1312­km-long river has a drainage basin of 93,180 sq km.

The Tapti (Also, Tapi) It rises near Multai (Betul district) 792 m above sea level in the plateau of the Satpura and has a drainage area of 64,750 sq km. It runs through Berar forming a narrow valley overhung by cliffs. The Purna tributary meets the Tapti before the latter enters Khandesh. It falls into the Gulf of Cambay after forming an estuary below Surat. The total length of this second largest west-flowing peninsular river is 724 km, the last 48 km of which is tidal.

The Luni It originates from Annasagar in the Aravallis, to the south-west of Ajmer. Its 450-km course is directed through a semi-arid tract somewhat parallel to the west of the Aravallis. It ends on the Sahni marshes north of the Rann of Kutch. Its several tributaries include Sarsuti, which rises from the Pushkar lake at Ajmer. It drains an area of 37,250 sq km.

The Sabarmati It originates from the lake of Jai Samudra in Udaipur district. It enters the sea at the head of the Gulf of Cambay after a course of 300 m. Its major tributaries are the Sabar and the Hathmati coming from Idar and Mahikatrtha respectively. It drains 21,674 sq km of area.

The Mahi
Rising in Gwalior it flows through Dhar, Ratlam and Gujarat and finally into the Gulf of Cambay. It is 560 km long, the last 65 km being tidal.

The East-flowing Rivers

The East-flowing Rivers The rivers that flow east to end up in the Bay of Bengal are as follows.
The Mahanadi The 858-km-Iong Mahanadi rises near Sihawa in Raipur district (Chhattisgarh). It flows towards the north-east and after meeting the Seonath, turns to the east and then south-east. It is a large river near Sambalpur, below which it flows through the Eastern Ghats and forms many distributaries at Cuttack before entering the sea. It drains an area of 1,32,090 sq km, about 53 per cent of which is in Madhya Pradesh and Chhattisgarh, 46 per cent in Orissa, and the rest is shared by Madhya Pradesh and Jharkhand.

The Godavari It is the largest river of the peninsula and the second largest river in the country. It is called the 'Vridha Ganga' and 'Dakshin Ganga'. It has a total length of 1,465 km and its drainage basin covers 3,13,839 sq km. It rises from Trambak in Nasik district in the Western Ghats and on its way receives several important tributaries including the Manjra, Penganga, Pranhita, Wardha, Wainganga, Indravati, Tal, Sabari, Mula and Pravara. It is 2,750 m wide at Rajahmundry below which it splits up into several branches to form a large delta before draining into the sea.

The Krishna The second largest east-flowing river of the peninsula rises north of Mahabaleswar from a height of 1,327 m in the Western Ghats. River Krishna, with a length of 1,400 km and a drainage basin of about 259,000 sq km, has Koyna, Malaprabha, Ghatprabha, Bhima, Yerla, Varna, Musi, Panchganga, Dudhganga and Tungabhadra as its main tributaries. The Tungabhadra, the largest tributary with a catchment area of 71,417 sq km, is formed of the Tunga and Bhadra rivers that originate in west Mysore and join below Shimoga (Mysore). The Tungabhadra joins Krishna near Kurnool town after a course of nearly 640 km. The Bhima has a catchment area of 76,614 sq km. It flows through southern Maharashtra and Andhra. Its delta begins to be formed a little below Vijayawada.

The Subarnarekha The river rises a little to the south­west of Ranchi in the Chhotanagpur plateau and flows generally in an easterly direction through Singhbhum, Mayurbhanj and Midnapore districts. It is about 395 km. long and has a catchment area of about 19,500 sq km.

The Brahmani Formed by the Koel and the Sankh joining in Gangpur, it flows through Bonai, Talcher and Balasore districts. The Baitarni river meets the Brahmani just before it falls into the Bay of Bengal. With a course of about 705 km, it drains 36,300 sq km.

The Baitarni Originating in the Keonjhar plateau in Orissa, it drains some 19,500 sq km in the eastern part of the peninsula. The river flows for 333 km.

The Penner Rising in the Kolar district (Karnataka), its chief tributaries are the Chitravati and the Papaghni. It flows through a gorge of Cudappah quartzites near Gandikota (Cudappah district) and enters the sea near the town of Nellore.

The Cauvery It rises from the Brahmagiri hills in the Coorg district at 1,341 m above sea level and drains the Mysore plateau before flowing into the plains. Cascades and falls mark its descent from the plateau. It runs for 805 km and its drainage basin is 80,290 sq km in area. The Bhavani, Noyil, Amaravati, Arkavati, Hemavati, Shimsa and Kabbani are its chief tributaries. The river is small in Mysore. At Srirangam, it divides into the northern Coleroon (Kollidam) and a southern branch that retains its name. The ancient port of Kaveripumpattinam was located at the mouth of this river. About 55 per cent of the Cauvery basin lies in Tamil Nadu, 41 per cent in Karnataka and three per cent in Kerala.

The Cauvery is almost perennial because it gets monsoonal rain from the south-west as well as the north­east streams.

The Tambrapani
It originates on Agastyamalai's slopes in the Western Ghats and drains into the Gulf of Mannar. The capital of the ancient Pandya Kingdom, Korkai once stood eight km inland from the present mouth of this river.


PENINSULAR RIVERS Many rivers traverse the Indian peninsula. Most of these show a mature stage of develop­ment particularly in the lower reaches of their valleys. Still, some rivers of the Western Ghats are an exception prob­ably because of an upward tilt and an uplift of the western part of the peninsula in the Tertiary era.

The west-flowing rivers form narrow and elongated catchment areas. Their great velocity and higher gradient make delta formation impossible. The east-flowing rivers,
greater in number, have wide catchment areas and form large deltas.

The Kosi andf The Damodar and The Brahmaputra

The Kosi Rising from peaks of Nepal, Tibet and Sikkim, the Kosi drains eastern Nepal and enters Saharsa district in Bihar via numerous channels. The channels flowing from north to south are received by the westernmost channel after it makes a bend to the east. It drains the area between Gosainthan and the Kanchenjunga in the Himalaya. The Arun-also Phungchu, in Tibetan-rises to the north of Gosainthan and runs south-west for 320 km to the south of the basin of Brahmaputra. It has a length of 730 km in India. It ends in the Ganga below Bhagalpur. Of the total
drained area of 86,900 sq km, 21,500 sq km is in India.

The Damodar It rises in the Chhotanagpur plateau near Tori in the Palamau district of Jharkhand. Its tributaries are the Garhi, Konar, Jamunia and the Barakar. It becomes a large river after its confluence with the Barakar. It joins the­Hooghly, after a course of nearly 541 km, a few kilometres below Calcutta. It drains 22,000 sq km of area.

The Brahmaputra System The Brahmaputra river, called Tsangpo in Tibet and Dihang in the Assam Himalaya, has its source at Tamchok Khambat Chorten in the Chemayungdung glacier which lies some 145 km from Parkha and near the source of the Karnali and the Sutlej. It is joined from the north by the Subansiri, Kameng, Jaibhorelli, Manas, Dhansiri (north) and Tisa. The Dhansiri (south), Burhi Dihing, Disang and Kopoli join the Brahmaputra from the south. It is met from the east by the Dibang, which drains the Himalaya east of Dihang, and the Luhit, flowing between Assam and Burma, near Sadiya. The Brahmaputra river system is one of the country's most important river systems that runs for 2,580 km (885 km in India) over 5,80,000 sq km (2,40,000 of them in India).

The Son, The Ram Ganga, The Sarda, The Ghaghra and The Gandak

The Son Originating from Amarkantak plateau, it flows to the north and meets the Kashmir range which diverts its course towards the north-east. It flows for 780 km before joining the Ganga near Ramnagar. It drains an area of 71,900 sq km. Its tributaries mostly join it on its right bank.

The Ram Ganga
Rising in the Kumaon Himalayas and flowing into the Ganga plain near Kalagarh, the Ram Ganga runs for 690 km before pouring itself into the Ganga near Kannauj. Some 32,000 sq km of area is drained by this river.

The Sarda
Also called the Chauka and Kali, it begins in the Great Himalaya and joins the right bank of the Ghaghra near Bahramghat. Flowing along the borders of India and Nepal, it levels the Himalaya at Baramdeo.

The Ghaghra Originating from east of Gangotri, it has a course of 1,080 km. More than half of the 127,500 sq. km. drained by it falls in Nepal territory. It abounds in silt and so is forced to shift its course often.

The Gandak Rising near the Nepal-China border at a height of 7,600 m in the central Himalaya, the Gandak enters Bihar in Champaran district, turns south-east and meets Ganga on its left at Sonpur. Even the Gandak often changes course. It runs for 425 km and drains 48,500 sq km of area. 9,540 sq km of this area is in India.

The Ganga and The Yamuna

The Ganga System India's most important river system, it covers more than a fourth of the country's total surface. The upper course of the Ganga is popularly known as Bhagirathi. The Gangotri glacier or Gomukh is considered as the source of this river. Another stream from the Alaka glaciers flowing southward is known as Alaknanda. The Ganga is formed by these two head streams when they meet at Devaprayag. The basin of the Ganga measuring about 838,200 sq km is the largest river basin in the country. The river flows for 2,510 km and drains 9,51,600 sq km. It has numerous large and small tributaries. The Ram Ganga, the Ghaghra, the Gandak and the Kosi are its major left bank tributaries while the Yamuna and the Son form the major right bank tributaries.

The Yamuna
The Yamuna rises at the Yamunotri glacier, which is to the west of the Ganga source, at a height of 6,315 m. It flows towards the south up to Agra and farther down towards the south-east direction till it joins the Ganga at Allahabad. The Chambal, Sind, Betwa and Ken are its important tributaries. The length of the Yamuna is 1,376 km from its source to Allahabad. It drains 3,59,000 sq km of area. The Chambal rises near Mhow in the Vindhyan range and flows up to Kota towards north. After reaching Pinahat, it turns to the east and joins Yamuna river
in the southern part of the Etawah district. It has a length I
of 1,050 km. Its important left bank tributary is the Banas. I
The Sind, the Betwa and the Ken flow towards the north I and form many ravines in the Ganga plain.

The Beas, The Sutlej and The Saraswati

The Beas (Sanskrit name: Vipasa or Argikiya) It rises on the southern face of the Rohtang Pass in Kulu Hills not far from the source of the Ravi at a height of 4000 m. Barely 10 km from its source it passes through a gorge at Koti, which is a chasm about 6 m wide and 275 m long. It cuts through the Dhauladhar range by another gorge near Larji and then flows through Kulu, Mandi and Kangra. It finally passes Kapurthala and Amritsar and joins the ~utlej in the south-west corner of Kapurthala. It has a total length of 470 km and drains an area of 25,900 sq km.

The Sutlej (Sanskrit name: Satadru or Satudri) The most important of the Indus tributaries in India, the Sutlej rises from the Rakas lake in Tibet at a height of 4,630 m. Its name in Tibet is Langchen Khambab and it rises in the glacial springs of Dulchu Khambab, 35 km west of Parkha which is an important trading centre between Kailas and Mansarovar. In Tibet it has a very narrow basin .between the Giri river on the east and the Beas on the west whose beds are however at' an elevation of 180 m to 215 m above the level of the Sutlej. The main tributary of the Sutlej is the Spiti river which drains a large area beyond the Central Himalayan Range. It also cuts deep into the rocks in the regions of Himachal Pradesh through which it flows. Even the Sutlej crosses the Dhauladhar range near Rampur through a narrow gorge. The river joins the Beas in the south-west corner of Kapurthala and the combined river joins the Indus near Mithankot. The total length of the Sutlej is about 1,050 km in India. The area drained by the river in India is 24,087 sq km.

The Saraswati The Saraswati rises in the Siwalik Hills of Sirmur on the borders of the Ambala district and enters the plains of Adhbadri. It disappears in the sands after passing by Bhawanipur and Balchhapar but reappears after a short distance, flowing through Karnal. The Ghaggar which also rises in the same region joins it at Rasula in Patiala after a course of 175 km. Farther on, the river is called the Hakra or Sotar. The Saraswati has been described in Vedic literature as a river greater even than the Indus and the Ganges.

Jhelum, The Chenab and Ravi

The Jhelum (Sanskrit: Vitasta) Rising in a spring of deep blue water at Seshanag at the head of its Lidar tributary, it flows for 110 km in a north-west direction and enters the Wular Lake. Its basin lies between the Great Himalayan Range and the Pir Panjal. Below Srinagar it is joined by the Sind river. From Baramula it flows through a narrow defile known as Basmangal, 2,130 m deep with very steep sides. After emerging from Jammu it flows past Pind Dadankheru and Bhera and is joined by the Chenab at Trimmu. The total length of the river is 725 km. 28,490 sq km of its total drainage area is in India. The Jhelum is an important river in Kashmir for it is the main waterway.

The Chenab
(Sanskrit name: Asikni or Chandrabhaga) The largest of the Indus tributaries, its two tributaries at the source are Chandra and Bhaga which rise on the opposite sides of Baralacha Pass (4,880 m) in Lahul. The Chandra is a stream of good size though it flows through a snow- clad, barren, uninhabited country. The Bhaga is a precipitous stream. They join at Tandi and then flow through Chamba in a north-westerly direction for 160 km in the trough between the Great Himalaya and the Pir Panjal. Cutting a deep gorge in the Pir Panjal, it turns southwards and later to the west to enter the plains near Akhnur. The Chenab has a total length of 1,800 km in India. It drains an area of 26,755 sq km in India.

The Ravi (Sanskrit name: Parushni or lravati) The smallest river of the Punjab and well-known as the river of Lahore, it rises near Rohtang Pass in the Kulu hills of Himachal Pradesh. It drains the northern slopes of the Dhauladhar range and the southern slopes of Pir Panjal. It leaves the basin through an inaccessible gorge with perpendicular sides and flows through Chamba in a north­westerly direction parallel to the Dhauladhar range, cutting through that range a few kilometres to the north-west of Dalhousie. It leaves the mountains at Basaoli after a course of 210 km during which it drops by 4,570 m in altitude (22 m per km). It finally joins the Chenab in Pakistan. Its total length is 725 km. Its drainage spreads over 5,957 sq km in India.

The Indus System

The Indus System It is one of the world's largest river systems. It comprises the following rivers.
The Indus (Sanskrit name: Sindhu) The Indus is the westernmost of the Himalayan rivers. It is one of the mightiest rivers of the world draining the glaciers and mountain slopes of many famous peaks like Masherbrum (7,821 m), Nanga Parbat (7,114 m), Rakaposhi (7,788 m), Tirich Mir (7,690 m) and receiving various great rivers as its tributaries. It has' a total length of over 2,900 km (709 km in India) and the drainage basin is estimated to have an area of 117,884 sq km in India.

Rising in Tibet at a height of 5,000 m, it flows for about 290 km over a flat country along the inner (northern) flank of the Ladakh Range. Then it cuts across that range at Thangra and flows along the outer flank fur another 480 km. Near Skardu (altitude 2,610 m), it cuts the Ladakh Range again, resuming the general trend of its course on the other side. After circling round the Nanga Parbat (8,114 m) it flows south-west through Hazara towards the plains of the Punjab. It passes through Gut in Chitral and then traverses 200 km of the wild territory of Kohistan entering the North West Frontier Province near Darband. At Attock, 1,385 km from. the source and 1,515 km from the mouth, it receives the Kabul tributary flowing in from Afghanistan and then flows due south. Below Attock, the Haroh and Sohan (Soan) rivers join the Indus. It falls into the Arabian Sea near Karachi.

The chief tributaries of the Indus are the Zanskar which rises on the Zanskar Range and joins the Indus below Leh; the Dras River which comes from the northern side of Zojila Pass and the plains of Deosai; the Shyok which rises on the northern side of the Karakoram range and cuts across to the south and joins the Indus near Kiris; the Shigar which drains the southern slopes of K2 and the Biafo and Baltoro glaciers; and the Gilgit which rises behind and cuts through the Karakoram range


The drainage of the sub-continent is related to the evolution of the physiographic divisions of the region. Situated within the high precipitation area under mon­soonal domain, India is drained by numerous rivers falling either into the Bay of Bengal or the Arabian Sea. The Ganga, Brahmaputra, Mahanadi, Godavari, Krishna and Cauvery are the major river systems draining into the Bay of Bengal whereas the major river systems draining into the Arabian Sea are the Indus, Sabarmati, Narmada, Tapti and rivers of the west coast farther south. Indian rivers may be classified into four types depending upon the natuw of the river, geographical location, source and drainage area covered: Himalayan, peninsular, coastal and rivers of inland drainage basin.
The rivers constitute an important natural resource as they make a great contribution to irrigation, domestic and industrial water supply, hydropower generation and inland water transport. According to size, rivers of India can be classified as follows.
(a) Major rivers having catchment area of over 20,000 sq km each. There are 14 such basins, having high rainfall (i.e., 63 million cubic metres per 100 sq km).
(b) Medium rivers, having a catchment area of 2,000­20,000 sq km each. 44 rivers fall in this category. These have medium rainfall (i.e., 45 million cu m per 100 sq km).
(c) Minor rivers having a catchment area of less them 2,000 sq km each. There are a large number of such rivers. These have low rainfall (i.e., 25 million cu m per 100 sq km).

HIMALAYAN RIVERS The Himalayan rivers play an important role as they flow cutting longitudinal and trans­verse sections in valleys, regimes, terraces, cones and fans in the piedmont base and shifting beds in the plains. The Himalayan rivers fall into four broad groups:
(a) The Pre-Himalayan rivers like the Arun, Indus, Sutlej and Brahmaputra.
(b) The Great Himalayan rivers like the Ganga, Kali, Ghagra, Gandak and Teesta.
(c) The Lesser Himalayan rivers like the Beas, Ravi, Chenab and Jhelum.
(d) The Siwalik rivers like the Hindon and the Solani.
The Himalayan rivers rise from the Great Himalaya,
Karakoram, Ladakh, Zanskar, Kailash and the Trans-Hima­layan ranges and ultimately join together to form three great river systems. These are the Indus system, the Ganga system and the Brahmaputra system.


1. Nile (Africa): The longest river, 6690 km; White Nile originates from Lake Albert in Uganda and Blue Nile from Ethiopia; the two join together at Khartoum in Sudan to form River Nile. After flowing through Egypt (the river's longest course), it falls into the Mediterranean Sea near Alexandria.

2. Amazon (South America): Originates from the Andes Mountain in Peru; tributaries come from Bolivia, Ecuador and Venezuela; the river flows mainly through Brazil and falls into the Atlantic Ocean.

3. Yangtze Kiang (Asia): Rises in north-east Tibet; and flows mainly through China, draining into the East China Sea.

4. Mississippi-Missouri (North America): Mississippi rises in Lake Itasca in Minnesota state of USA; Missouri joins it at Saint Louis; together, they flow into the Gulf of Mexico at New Orleans.

5. Mackenzie (North America): Rising in Great Slave Lake, it flows through Canada to Mackenzie Bay in the Arctic Ocean.

6. Mekong (Asia): Rises in Tibet, enters China through which it flows and later forms, for some distance, the borders between Thailand and Laos and falls into the South China Sea.

7. Niger (Africa): Rising near Sierra Leone, it crosses Niger and flows mainly through Nigeria and enters the Atlantic Ocean at the Gulf of Guinea.

8. Murray-Darling (Australia): Murray rises in the Australian Alps; Darling, its biggest tributary, joins it in the state of New South Wales. Both empty into the Indian Ocean at Encounter Bay.

9. Volga (Europe): Rises in Valdai Plateau north-west of Moscow, Russia, and enters the Caspian Sea at Astra­khan.

10. Danube (Europe): Rises near Baden in Germany, flows through Austria, Hungary, Czechoslovakia and Yugoslavia, crosses Romania and enters the Black Sea.

Rivers and Lakes

A river is a large stream of fresh water flowing downhill within a channel to enter another river or a lake or sea. All rivers ultimately receive their water from precipitation, though this relation is not a very simple one. The flow of a river depends upon three main factors: the amount and intensity of rainfall, governed by climatic factors; the permeability of the surface on which it is flowing; and the morphological properties of the drainage basin. The nature of the vegetation cover also plays an important role. When water flows in a stream, it is subject to two basic forces: gravity, aimed downstream and causing the flow; and frictional resistance between the water and the river bed. The effect of friction ensures an uneven velocity of water flow in the river. Thus, water near the centre moves the fastest while it is slow near the banks.


The place at which the river begins to flow is called its source. It may be in the melt waters of a glacier, e.g., the Rhone (France), or in a lake, e.g., the Nile (Africa), or in a spring, e.g., the Thames (England), or in a region of steady rainfall, e.g., the Zaire (Africa). The place where the river ends is called a river's mouth. It is usually in the sea, e.g., the Indus (Arabian Sea) and the Amazon (Atlantic), although it may be in a lake, e.g., the Volga (Caspian), or in a salt swamp, e.g., the Chari River (Lake Chad) and the Tarim River (Lap Nor).

A mature river has three sections: (i) the upper course representing the stage of youth of a river, called the torrent stage; (ii) the middle course, representing the state of maturing called the valley stage, and (Hi) the lower course, representing the stage of old age and called the plain stage. In the stage of youth, the river flows turbulently in a narrow steep-sided valley whose floor is broken by (a) 'potholes' or circular depressions in the river bed, caused by pebbles,
(b) waterfalls, occurring where the bed of the river becomes suddenly steepened. Some deep and narrow valleys having very steep sides are called gorges. These are formed where a waterfall retreats upstream. The head waters of the Ganga have cut deep gorges in the Himalayas. The Indus Gorge in Kashmir is 5180 metres. Canyons are large gorges, formed in dry regions where large rivers are actively eroding vertically. A canyon is a deep valley with steep, near vertical sides. River Colorado has cut a gorg~ 1.6 km (1 mile) deep and 480 km (300 miles) long into the Colorado plateau (USA).

As the valley widens, meanders are formed. A meander is a loop. in the course of a river channel. Water flows in corkscrew manner, causing erosion on the concave bank and deposition on the convex bank.
In the mature stage form the flood plains-low lying land composed of deposits of sediment (alluvium). Mean­ders migrating downstream cause widening of the valley. Ox-bow lakes are produced by cut-offs in a meander during floods.

Reaching old age, the river deposits its load into the sea or lake into which it flows. The deposited load some­times collects in the river mouth, where it builds up into a low-lying swampy plain called a delta. The river divide~ into several channels due to the depositions at its mouth, called distributaries. Arcuate deltas are formed by coarse sediments like gravel and sand and are triangular in shape, having many distributaries, e.g., in Rivers Ganga, Indus, Nile, Niger, Hwang-Ho. Bird's foot deltas are composed of very fine sediments, having few distributaries with clearly defined channels, like the Mississippi delta. An estuarine delta develops in the mouth of a submerged river, e.g., deltas of Elbe (Germany) and Ob (Russia).

A river does three types of work: it erodes, and most erosion takes place in the upper course; it transports: a process dominant in the middle course; and it deposits: depositional process is dominant in the lower course of the river. A river's ability to work, Le., to erode and transport material, depends upon its energy. Potential energy is provided by weight and the elevation of water. This is converted into downflow by gravity and thus into kinetic energy. However, about 95 per cent of this energy is lost due to frictional resistance.