NCERT Class 11 India Physical Geography Chapter 3: Drainage System

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  • Drainage
  • Drainage System
  • Catchment Area
  • Drainage Basin
  • Water Divide
  • Rivers, nalas and channels
  • The flow of water through well-defined channels is known as ‘drainage’ and the network of such channels is called a ‘drainage system’ .
  • Is it perennial (always with water) or ephemeral (water during rainy season, and dry, otherwise) ?
  • A river drains the water collected from a specific area, which is called its ‘catchment area’ .
  • An area drained by a river and its tributaries is called a drainage basin.
  • Watershed – boundary line separating one drainage from another
  • The catchments of large rivers are called river basins while those of small rivulets and rills are often referred to as watersheds.
  • Watersheds are small in area while the basins cover larger areas

River Regime

  • Pattern of water that flows in a river is river regime
  • Varies from season to season
  • Northern – perennial , fed by glaciers
  • South rivers- no glaciers and more fluctuations and controlled by rainfall
  • The discharge is the volume of water flowing in a river measured over time. It is measured either in cusecs (cubic feet per second) or cumecs (cubic meters per second) .
  • Ganga has its minimum flow during the January-June period. The maximum flow is attained either in August or in September. Ganga maintains a sizeable flow in the early part of summer due to snow melt before the monsoon rains begin.
  • The mean maximum discharge of the Ganga at Farakka is about 55,000 cusecs while the mean minimum is only 1,300 cusecs
  • Narmada has a very low volume of discharge from January to July but it suddenly rises in August when the maximum flow is attained. The fall in October is as spectacular as the rise in August. The flow of water in the Narmada, as recorded at Garudeshwar (maximum)
  • Godavari has the minimum discharge in May, and the maximum in July-August. After August, there is a sharp fall in water flow although the volume of flow in October and November. At Polavaram (maximum)

Usability of River Water

During the rainy season, much of the water is wasted in floods and flows down to the sea. Similarly, when there is a flood in one part of the country, the other area suffers from drought.

(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 (line connecting the lowest points of successive cross-sections along the course of a valley or river.)

  • Cremation of bodies near riverbanks, pollution by industry and household sewage, bathing and washing of clothes
  • Ganga Action Plan

Types of Drainage

  • Dendritic – tree – rivers in northern plains
  • Radial - originate from a hill and flow in all directions – Amarkantak
  • Trellis – join at right angle
  • Centripetal – discharge water in the lake from all directions

Indian Drainage System

Indian Drainage System
  • 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 of Bengal drainage. They are separated from each other through the Delhi ridge, the Aravalis and the Sahyadris
  • Nearly 77 per cent of the drainage area consisting of the Ganga, the Brahmaputra, the Mahanadi, the Krishna, etc. is oriented towards the Bay of Bengal while 23 per cent comprising the Indus, the Narmada, the Tapi, the Mahi and the Periyar systems discharge

Their Waters in the Arabian Sea

On the basis of the mode of origin, nature and characteristics, the Indian drainage may also be classified into the Himalayan drainage and the Peninsular drainage. Although it has the problem of including the Chambal, the Betwa, the Son, etc. which are much older in age and origin than other rivers that have their origin in the Himalayas, it is the most accepted basis of classification

Watershed Size

  • Macro
  • Meso
  • Micro
  • Major river basins with more than 20,000 sq. km of catchment area. It includes 14 drainage basins such as the Ganga, the Brahmaputra, the Krishna, the Tapi, the Narmada, the Mahi, the Pennar, the Sabarmati, the Barak, etc.
  • Medium river basins with catchment area between 2,000 - 20,000 sq. km incorporating 44 river basins such as the Kalindi, the Periyar, the Meghna, etc.
  • Minor river basins with catchment area of less than 2,000 sq. km include fairly good number of rivers flowing in the area of low rainfall

Himalayan Drainage

  • Indus, Ganga, and Brahmaputra – form V-shaped valleys and rapids. Deposition as flood plains and braided channels
  • Fed by melting of snow and precipitation – they are perennial - pass through the giant gorges carved out by the erosional activity
  • River Kosi, also known as the ‘sorrow of Bihar’ – brings sediments form upper course and gets blocked
  • Shiwalik or Indo-Brahma traversed the entire longitudinal extent of the Himalaya from Assam to Punjab and onwards to Sind, and finally discharged into the Gulf of Sind near lower Punjab during the Miocene period some 5 - 24 million years ago - lacustrine origin and alluvial deposits consisting of sands, silt, clay, boulders
  • It is opined that in due course of time Indo – Brahma river was dismembered into three main drainage systems: (i) the Indus and its five tributaries in the western part; (ii) the Ganga and its Himalayan tributaries in the central part; and (iii) the stretch of the Brahmaputra in Assam and its Himalayan tributaries in the eastern part – due to Pleistocene upheaval in the western Himalayas and upliftment of Potwar Plateau (Delhi Ridge)
  • Downthrusting of the Malda gap area between the Rajmahal hills and the Meghalaya plateau during the mid-pleistocene period, diverted the Ganga and the Brahmaputra systems to flow towards the Bay of Bengal.

Indus River

  • largest river basins of the world,
  • covering an area of 11,65, 000 sq. km
  • Indus also known as the Sindhu
  • It originates from a glacier near Bokhar Chu in Tibetan region in Kailash Mountain range
  • In Tibet, it is known as ′ Singi Khamban, or Lion ′ s mouth. After flowing in the northwest direction between the Ladakh and Zaskar ranges, it passes through Ladakh and Baltistan
  • Forms a spectacular gorge near Gilgit in Jammu and Kashmir
  • enters into Pakistan near Chilas in the Dardistan region
  • tributaries such as the Shyok, the Gilgit, the Zaskar, the Hunza, the Nubra, the Shigar, the Gasting and the Dras. It finally emerges out of the hills near Attock where it receives the Kabul river on its right bank
  • right bank of the Indus are the Khurram, the Tochi, the Gomal, the Viboa and the Sangar – originate at Sulaiman ranges
  • The river flows southward and receives ‘Panjnad’ a little above Mithankot.
  • Panjnad is the name given to the five rivers of Punjab, namely the Satluj, the Beas, the Ravi, the Chenab and the Jhelum.
  • Discharge in Arabian sea east of Karachi

Indus Tributaries

  • The Jhelum rises from a spring at Verinag situated at the foot of the Pir Panjal in the south-eastern part of the valley of Kashmir. It flows through Srinagar and the Wular lake before entering Pakistan through a deep narrow gorge. It joins the Chenab near Jhang in Pakistan.
  • The Chenab is the largest tributary of the Indus. It is formed by two streams, the Chandra 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 rises west of the Rohtang pass in the Kullu hills of Himachal Pradesh and flows through the Chamba valley of the state. Before entering Pakistan and joining the Chenab near Sarai Sidhu, it drains the area lying between the southeastern part of the Pir Panjal and the Dhauladhar ranges.
  • The Beas is tributary of the Indus, originating from the Beas Kund near the Rohtang Pass at an elevation of 4,000 m above the mean sea level. The river flows through the Kullu valley and forms gorges at Kati and Largi in the Dhaoladhar range. It enters the Punjab plains where it meets the Satluj near Harike.
  • The Satluj originates in the ‘Raksas tal’ near Mansarovar at an altitude of 4,555 m in Tibet where it is known as Langchen Khambab. It flows almost parallel to the Indus for about 400 km before entering India and comes out of a gorge at Rupar. It passes through the Shipki La on the Himalayan ranges and enters the Punjab plains. It is an antecedent river. It is a very important tributary as it feeds the canal system of the Bhakra Nangal project.

Ganga River

  • It rises in the
  • Gangotri glacier near Gaumukh (3,900 m)
  • in the Uttarkashi district of Uttarakhand – called as Bhagirathi
  • Cuts through the Central and the Lesser Himalayas in narrow gorges. At Devprayag, the Bhagirathi meets the Alaknanda; hereafter, it is known as the Ganga
  • Alaknanda has its source in the Satopanth glacier above Badrinath. The Alaknanda consists of the Dhauli and the Vishnu Ganga which meet at Joshimath or Vishnu Prayag
  • The other tributaries of Alaknanda such as the Pindar joins it at Karna Prayag while Mandakini or Kali Ganga meets it at Rudra Prayag. The Ganga enters the plains at Haridwar
  • Flow is South, SE and then east before splitting into Bhagirathi and the Padma
  • length of 2,525 km. It is shared by Uttarakhand (110 km) and Uttar Pradesh (1,450 km) , Bihar (445 km) and West Bengal (520 km) . The Ganga basin covers about 8.6 lakh sq. km area in India alone
  • largest in India having a number of perennial and non-perennial rivers originating in the Himalayas in the north and the Peninsula in the south
  • Empties in Bay of Bengal near Sagar Island

Ganga Tributaries

  • Son – right bank, originate at Amarkantak; forming a series of waterfalls at the edge of the plateau, it reaches Arrah, west of Patna, to join the Ganga
  • Left bank - Ramganga, the Gomati, the Ghaghara, the Gandak, the Kosi and the Mahananda
  • Yamuna- westernmost, longest, source in the Yamunotri glacier on the western slopes of Banderpunch range. It joins the Ganga at Prayag (Allahabad) .
  • Tributaries of Yamuna – right bank (Chambal, the Sind, the Betwa and the Ken) ; Left bank – (Hindan, the Rind, the Sengar, the Varuna)
  • Chambal – originates in Mhow, Malwa (MP) , towards Kota (Gandhisagar dam) -traverses down to Bundi, Sawai Madhopur and Dholpur, and finally joins the Yamuna. Famous for badlands – Chambal ravines
  • Gandak comprises two streams, namely Kaligandak and Trishulganga. It rises in the Nepal Himalayas between the Dhaulagiri and Mount Everest and drains the central part of Nepal. It enters the Ganga plain in Champaran district of Bihar and joins the Ganga at Sonpur near Patna.
  • Ghaghara originates in the glaciers of Mapchachungo and tributaries – Tila, Seti and Beri cut a deep gorge at Shishapani. river Sarda (Kali or Kali Ganga) joins it in the plain before it finally meets the Ganga at Chhapra
  • Sarda or Saryu river rises in the Milam glacier in the Nepal Himalayas where it is known as the Goriganga. Along the Indo-Nepal border, it is called Kali or Chauk, where it joins the Ghaghara.
  • Kosi – antecedent source to the north of Mount Everest in Tibet, where its main stream Arun rises. After crossing the Central Himalayas in Nepal, it is joined by the Son Kosi from the West and the Tamur Kosi from the east. It forms Sapt Kosi after uniting with the river Arun
  • Ramganga - river rising in the Garhwal hills near Gairsain; change course in SW direction after crossing the Shiwalik and enters into the plains of Uttar Pradesh near Najibabad. Finally, it joins the Ganga near Kannauj
  • Damodar – eastern margin of Chotanagpur Plateau where it flows through a rift valley and finally joins the Hugli. Barakar is its main tributary. Once known as the ‘sorrow of Bengal’ ,
  • Mahananda - rising in the Darjiling hills. It joins the Ganga as its last left bank tributary in West Bengal

Brahmaputra System

  • Largest river of world - origin in the Chemayungdung glacier of the Kailash range near the Mansarovar lake
  • traverses eastward longitudinally for a distance of nearly 1,200 km in a dry and flat region of southern Tibet, where it is known as the Tsangpo (Purifier)
  • Rango Tsangpo is the major right bank tributary of this river in Tibet. It emerges as a turbulent and dynamic river after carving out a deep gorge in the Central Himalayas near Namcha Barwa
  • The river emerges from the foothills under the 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 and Lohit; thereafter, it is known as the Brahmaputra
  • left bank tributaries are the Burhi Dihing and Dhansari (South)
  • right bank tributaries are the Subansiri, Kameng, Manas and Sankosh
  • Subansiri - origin in Tibet, is an antecedent river
  • Brahmaputra enters into Bangladesh near Dhubri and flows southward. In Bangladesh, the Tista joins it on its right bank from where the river is known as the Jamuna
  • It finally merges with the river Padma, which falls in the Bay of Bengal.
  • Brahmaputra is well-known for floods, channel shifting and bank erosion

Peninsular Drainage

  • It is older than Himalayas
  • broad, largely graded shallow valleys, and maturity of the rivers.
  • Most of the major Peninsular rivers except Narmada and Tapi flow from west to east.
  • Chambal, the Sind, the Betwa, the Ken, the Son, originating in the northern part of the Peninsula belong to the Ganga river system.
  • Mahanadi, Godavari, the Krishna and the Kaveri – fixed course, absence of meanders and nonperennial flow of water


(i) Subsidence of the western flank of the Peninsula leading to its submergence below the sea during the early tertiary period. Generally, it has disturbed the symmetrical plan of the river on either side of the original watershed.

(ii) Upheaval of the Himalayas when the northern flank of the Peninsular block was subjected to subsidence and the consequent trough faulting. The Narmada and The Tapi flow in trough faults and fill the original cracks with their detritus materials. Hence, there is a lack of alluvial and deltaic deposits in these rivers.

(iii) Slight tilting of the Peninsular block from northwest to the southeastern direction gave orientation to the entire drainage system towards the Bay of Bengal during the same period.

Peninsular Rivers

  • Mahanadi rises near Sihawa in Raipur district of Chhattisgarh and runs through Odisha to discharge its water into the Bay of Bengal. It is 851 km long: 53 % in MP and Chattisgarh while 47 % in Odisha
  • Godavari – largest peninsular system Dakshin Ganga. It rises in the Nasik district of Maharashtra. run through Maharashtra, Madhya Pradesh, Chhattisgarh, Odisha and Andhra Pradesh. It is 1,465 km long. 49 % Maharashtra, 20 % MP & Chhattisgarh & rest Andhra Pradesh. Penganga, the Indravati, the Pranhita, and the Manjra are its principal tributaries. The Godavari is subjected to heavy floods in its lower reaches to the south of Polavaram - where it forms a picturesque gorge. It is navigable only in the deltaic stretch. The river after Rajamundri splits into several branches forming a large delta
  • Krishna – second largest east flowing river, total length is 1,401 km. The Koyna, the Tungbhadra and the Bhima are its major tributaries. 27 % Maharashtra, 44 % Karnataka and 29 % Andhra and Telangana
  • Kaveri rises in Brahmagiri hills (1,341m) of Kogadu district in Karnataka. Its length is 800 km. Upper region SW monsoon while lower regime NE monsoon – water throughout the year. 3 % Kerala, 41 % Karnataka and 56 % Tamil Nadu. Kabini, the Bhavani and the Amravati.
  • Narmada – originate at western flank of the Amarkantak plateau. between the Satpura in the south and the Vindhyan range in the north forms Dhuandhar waterfall near Jabalpur. After flowing a distance of about 1,312 km, it meets the Arabian sea south of
  • Bharuch. Have Sardar Sarovar Dam.
  • Tapi - originates from Multai in the Betul district of Madhya Pradesh. It is 724 km long. 79 % Maharashtra, 15 % MP and 6 % Gujarat
  • Luni – Rajasthan originates near Pushkar in two branches, i.e.. the Saraswati and the Sabarmati, which join with each other at Govindgarh. From here, the river comes out of Aravali and is known as Luni. It flows towards the west till Telwara and then takes a
  • southwest direction to join the Rann of Kuchchh. The entire river system is ephemeral.

Short Courses

  • Shetruniji - rises near Dalkahwa in Amreli district
  • Bhadra - Anjali village in Rajkot district.
  • Dhadhar - Ghantar village in Panchmahal district
  • Vaitarna - Trimbak hills in Nasik district at an elevation of 670 m.
  • Kalinadi - rises from Belgaum district and falls in the Karwar Bay
  • Bedti river - lies in Hubli Dharwar
  • Sharavati - originates in Shimoga district of Karnataka
  • Mandovi & Zauri – Goa
  • Bharathapuzha or Ponnani – longest in Kerala, rises near Anamalai
  • Periyar – 2nd largest in Kerala
  • Pamba – Kerala – falls in Vemobanad lake
  • Rivers draining towards east - Subarnrekha, the Baitarni, the Brahmani, the Vamsadhara, the Penner, the Palar and the Vaigai.

Namami Ganga Project

‘Namami Gange Programme’ , is an Integrated Conservation Mission, approved as “Flagship Programme” by the Union Government in June 2014 with the twin objectives of effective abatement of pollution, conservation and rejuvenation of the National River Ganga. Main pillars of the Namami Gange Programme are:

  • Sewerage Treatment Infrastructure
  • River-Front Development
  • River-Surface Cleaning
  • Biodiversity
  • Afforestation
  • Public Awareness
  • Industrial Effluent Monitoring
  • Ganga Gram.